Browse Topic: Vehicle deceleration

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Research on the Application of Eddy Current Retarders in Aircraft Arresting Systems2026-99-16217/24/2026
At present, the aircraft arresting system in our country is the fixed water turbine type. This kind of equipment cannot achieve the arrestment of multiple aircraft types, and the arresting distance cannot be adjusted. According to these problems of the aircraft arresting system in our country, the eddy current retarding device is added, based on the water turbine braking device of the aircraft arresting system. It derives the differential equation for an aircraft arresting system with a water turbine brake and eddy current retarder using mathematical modeling. Four types of aircraft parameters are selected, and MATLAB is used as a simulation tool to verify the reliability of the arresting system after installing the eddy current retarder. This research can improve the arresting support ability and make the arresting device meet the arresting requirements of different types of aircraft.
Wei, Yan, Feng, Chunchun, Wang, Jianwu, Li, Binghong, Yang, Yang
Advanced Tool for Traffic Crash Analysis: An AI-Driven Multi-Agent Approach to Pre-Crash Reconstruction09-14-01-00335/4/2026
Traffic collision reconstruction traditionally relies on human expertise and, when performed properly, can be incredibly accurate. However, attempting to perform pre-crash reconstruction, i.e., reconstructing the driver and vehicle behaviors that preceded the actual crash, poses significantly more challenges. This study develops a multi-agent artificial intelligence (AI) framework that reconstructs pre-crash scenarios and infers vehicle behaviors from fragmented collision data. We present a two-phase collaborative framework combining reconstruction and reasoning phases. The system processes 277 rear-end lead vehicle deceleration (LVD) collisions from the Crash Investigation Sampling System (CISS; 2017–2022), integrating textual crash reports, structured tabular data, and visual scene diagrams. Phase I generates natural language crash reconstructions from multimodal inputs. Phase II performs in-depth crash reasoning by combining these reconstructions with the temporal event data recorder (EDR). This enables precise identification of striking and struck vehicles while isolating the EDR records most relevant to the collision moment, thereby revealing crucial pre-crash driving behaviors. For validation, we applied it to all LVD cases, focusing on a subset of 39 complicated EDR cases where multiple EDR records per collision introduced possible ambiguity (e.g., due to missing or conflicting data). Ground truth was established via consensus between manual annotations (two independent researchers), with a separate large language model (LLM) used only to flag possible conflicts for re-checking. In the full end-to-end evaluation, the framework achieved 100% accuracy across all 4155 trials (277 cases × 5 runs × 3 models), with three reasoning models producing identical outputs, confirming that performance derives from the structured prompt design rather than model-specific characteristics. In contrast, research analysts without specialized reconstruction training achieved 92.31% accuracy on the same 39 complex cases. In separate ablation experiments on the 39 complicated EDR cases, where one randomly selected Phase I output from the full end-to-end evaluation was fixed as the unified input for Phase II and each model was tested with 10 independent runs, removing the structured reasoning anchors reduced case-level accuracy from 99.7% to 96.5%, with errors spreading from a single output type to multiple analytical dimensions. The system maintained robust performance even when processing incomplete data. This zero-shot evaluation, conducted without any domain-specific training or fine-tuning, demonstrates that the framework’s effectiveness stems from its multi-agent architecture and prompt engineering, offering a scalable approach for AI-assisted pre-crash analysis.
Xu, Gerui, Chen, Boyou, Guo, Huizhong, LeBlanc, Dave, Kusari, Arpan, Yarbasi, Efe, Ahmed, Ananna, Sun, Zhaonan, Bao, Shan
From Prediction to Design: Using Context-Aware Graph Neural Networks and Explainable AI to Anticipate Transfer-of-Control2026-01-00494/7/2026
Drivers often interact with partial automation (SAE Level 2) systems, initiating transfer of control (TOC) either by handing control over to the automation or by taking it back. Accurately predicting these interactions may inform the design of future automation systems that adapt proactively to the operating context, enhance comfort, and ultimately may improve safety. We present a context-aware framework that generates a unified driver–vehicle–environment representation by fusing data from in-cabin video of the driver and of the forward roadway with vehicle kinematics, driver glance, and hands-on-wheel behaviors. This representation was encoded in a hierarchical Graph Neural Network that classified driver-initiated TOCs to: (i) Manual-to-automation and (ii) Automation-to-manual transitions and predicted time-to-TOC. Shapley-based explainable AI was used to quantify how the importance of behavioral, contextual, and kinematic cues evolved in the seconds preceding a TOC. Analysis of a naturalistic dataset of 1,565 driver-initiated TOCs from 16 experienced drivers revealed distinct patterns. Manual-to-automation transitions were preceded by lane count increases, acceleration, and spikes in glances to the instrument-cluster. In contrast, Automation-to-manual transitions were associated with lane count reductions, higher surrounding-vehicle density, deceleration, reduction in secondary-task engagement, and higher steering wheel control. Together, these patterns highlight key cues for predicting the TOC type and time-to-TOC. Using environment-only features, the classifier achieved 78% accuracy; adding vehicle kinematics increased accuracy to 84%, and incorporating driver behavior features further improved prediction to 90%. Across prediction horizons, the Manual-to-automation TOC was consistently predicted more accurately than the automation-to-manual TOC. Shapley analyses underscore that driver behavior provided the strongest cues for predicting TOCs, highlighting the value of fusing driving context with information obtained from monitoring the driver behavior to anticipate the type of driver-automation interaction and its timing.
Zhao, Zhouqiao, Gershon, Pnina
The Effect of Tire Tread Depth on Antilock-Brake System (ABS) Decelerations on Dry and Wet Asphalt and Concrete Road Surfaces2026-01-05494/7/2026
The effect of tire tread depth on the deceleration performance of anti-lock brake systems (ABS) in newer vehicles is not well studied. A single sport-utility vehicle (SUV) was used to perform a series of 216 ABS-engaged braking tests on dry and wet asphalt and concrete surfaces using six sets of four tires with tread depths varying from 0.8 mm (1/32″) to 7.1 mm (9/32″). Vehicle speed and deceleration as a function of time were calculated from 5th-wheel displacement data sampled at 200 Hz. Braking tests were initially conducted on a dry surface, after which a water truck distributed water onto the road to create a wet condition and additional tests of each tire set were conducted. Overall, average deceleration levels did not vary significantly across the tires sets with tread depths from 7.1 mm (9/32″) down to 2.4 mm (3/32″) for both road surfaces in both dry and wet conditions. Compared to the deceleration levels at these larger tread depths, dry deceleration levels were greater for tread depths of 0.8 mm (1/32″) and 1.8 mm (2/32″) on both asphalt and concrete, and wet deceleration levels were lower for tread depths of 0.8 mm (1/32″) on both asphalt and concrete. These findings provide a source for analysts to estimate how tread depth affects deceleration for ABS-equipped vehicles.
Miller, Ian, King, David, Siegmund, Gunter P.
Human-Like Automatic Braking Algorithm Based on Kinematic Cue: Yield Behavior Analysis and Fuzzy Controller Design10-10-03-00192/25/2026
Pedestrians are among the most vulnerable participants in traffic, particularly when crossing the road. Extensive research has been conducted globally on the yielding behavior analysis of vehicle–pedestrian interaction and the design of automatic vehicle braking systems to mitigate pedestrian casualties. However, few studies have comprehensively addressed lateral risks using implicit kinematic cues in pedestrian–vehicle interactions. Moreover, the design of collision avoidance systems has rarely taken into account driving behavior, along with the pedestrian’s kinematics and crossing behavior. This article presents a human-like automatic braking fuzzy control strategy for pedestrian–vehicle collision avoidance, combining the advantages of professional driver emergency braking behavior and kinematic interaction cues. First, a high-fidelity driving simulator is used to investigate the yielding behavior of pedestrian–vehicle interaction when pedestrians cross the road. Second, the intrusion position (XP), as a new lateral risk index, is designed to overcome the limitation of lateral distance in complex pedestrian–vehicle interaction scenarios. Various metrics are considered to analyze driver emergency braking behavior using statistical methods from both lateral and longitudinal aspects. Subsequently, based on driver braking behavior, the human-like automatic braking fuzzy control strategy is proposed. Finally, simulation examples verify the reliability of the analysis results and the proposed controller’s effectiveness. Compared with a conventional automatic braking system, the timing of interventions of the proposed system is on average 2.9 s earlier, and the braking deceleration is reduced by 3.59 m/s2.
Zhang, Wenyan, Huang, Xiaorong, Sun, Shulei, Fu, Kairong, Xiong, Qing, Huang, Haibo
Predictive SoC Management for Enhanced Recuperation Efficiency in Electric Vehicles2026-26-01541/16/2026
In recent years, the automotive industry has been looking into alternatives for conventional vehicles to promote a sustainable transportation future having a lesser carbon footprint. Electric Vehicles (EV) are a promising choice as they produce zero tail pipe emissions. However, even with the demand for EVs increasing, the charging infrastructure is still a concern, which leads to range anxiety. This necessitates the judicious use of battery charge and reduce the energy wastage occurring at any point. In EVs, regenerative braking is an additional option which helps in recuperating the battery energy during vehicle deceleration. The amount of energy recuperated mainly depends on the current State of Charge (SoC) of the battery and the battery temperature. Typically, the amount of recuperable energy reduces as the current SoC moves closer to 100%. Once this limit is reached, the excess energy available for recuperation is discharged through the brake resistor/pads. This paper proposes a method to minimize the energy wastage due to the SoC constraints by predicting an optimal start SoC. The optimal SoC is calculated in such a way that it maximizes energy recovery during regeneration while taking the route attributes, weather conditions, and charger availability into account. On a hilly route, it was noticed that the recuperated energy was 5 times more while using the optimal SoC, compared to the 100% start SoC. This reduction in SoC prevents overcharging and contributes to lesser charging time. Consequently, this approach would positively impact overall battery health, energy efficiency, and contribute to promoting sustainability.
Barik, Madhusmita, S, Sethuraman, Aruljothi, Sathishkumar
Automatic Brake Failure Detection with Electromagnetic Braking System2025-28-037310/30/2025
Brake failures in the vehicles can cause hazardous accidents so having a better monitoring and emergency braking system is very important. So, this project consists of an autonomous brake failure detector integrated with Automatic Braking using Electromagnetic coil braking which detects the braking failure at the time and applied the combinations of the brakes, to overcome this kind of accidents. So, here the system comprises of IR sensor circuit, control unit and electromagnetic braking system. How it works: The IR sensor monitors the brake wire, and if the wire is broken, the control unit activates the electromagnetic brakes, stopping the vehicle in a safe manner. This system enhances vehicle safety by ensuring immediate braking action without driver intervention. Key advantages include real-time brake monitoring, reduced mechanical wear, quick response time, and an automatic failsafe mechanism. The system’s minimal reliance on hydraulic components also makes it suitable for harsh or variable conditions. The proposed system can be widely implemented in automobiles, especially those using drum brakes, as well as railway systems to prevent accidents due to brake failure. Future advancements in predictive maintenance, machine learning, and AI integration could further improve the reliability, adaptability, and overall efficiency of this advanced braking system.
Raja, Selvakumar, John, Godwin, Siddarth, J P, Senthilkumar, Akash, Mathew, Abhay, R. S., Nakandhrakumar, Nandagopal, Sasikumar, Arumugam, Sivasankar
Development of an Imperceptible Brake Failure Control Technology and Real Vehicle Application10-09-02-00154/26/2025
With the advancement of control technology in the automotive field, there is a possibility of cross-system redundant control between various actuators. As for the braking system, current brake-by-wire system often uses mechanical backup braking methods to give the vehicle a certain braking capacity after failure. However, in the mechanical backup braking mode, the brake master cylinder is connected to the supporting wheel cylinder, and the brake assist is lost, which leads to an increase in brake pressure and makes it difficult for the driver to step on the brake pedal. Meanwhile, due to the limitation of the brake master cylinder stroke, the maximum braking deceleration of the vehicle is only 3 m/s2 after the driver fully presses the brake pedal. The above two defects greatly affect the safety of the vehicle during backup braking. To solve the above problems, this article takes electric vehicles as the research object, designs a new type of hydraulic circuit for the braking system, and develops a backup braking method that integrates the drive motor and electronic parking system. This article builds a vehicle simulation model and selects real vehicles for actual testing. The results showed that in backup braking mode, the driver obtained the braking sensation during normal braking, and the maximum braking deceleration of the vehicle reached 10 m/s2. Overall, the backup braking method designed in this article effectively solves the drawbacks of the current brake-by-wire system and improves the safety of vehicles during backup braking.
Tian, Boshi, Li, Liang, Liao, Yinsheng, Lv, Haijun, Hu, Zhiming, Sun, Yue, Qu, Wenying
Research on Torque Management Safety Monitoring Control for Hybrid Vehicles2025-01-85794/1/2025
Hybrid vehicles are driven by the vehicle controller, engine controller and motor controller through torque control, and there may be unexpected acceleration or deceleration of the vehicle beyond the driver's expectation due to systematic failure and random hardware failure. Based on the torque control strategy of hybrid vehicles, the safety monitoring model design of torque control is carried out according to the ISO 26262 safety analysis method. Through the establishment of safety goals and the analysis of safety concepts, this paper conducts designs including the driver allowable torque design for safety monitoring, the driver torque prediction design for safety monitoring, the rationality judgment design of driver torque for safety monitoring, the functional safety degradation design, and the engine start-stop status monitoring, enabling the system to transition to a safe state when errors occur. Firstly, the design of the driver's allowable torque includes the allowable requested torque of the accelerator pedal, the crawling allowable requested torque, and the coordination and arbitration with the external intervention torque, the Adas requested torque, and the vehicle's allowable torque based on vehicle speed and acceleration to obtain the allowable torque finally used for functional safety torque monitoring. Secondly, the driver's torque prediction design for safety monitoring includes the prediction of the indicated torque of the crankshaft based on the angular acceleration signal of the crankshaft. Introducing torque monitoring in the vehicle control strategy to prevent the generation of uncontrollable torque due to failure and avoid the vehicle being in dangerous states.
Jing, Junchao, Wang, Ruiguang, Liu, Yiqiang, Huang, Weishan, Dai, Zhengxing
A Model for the Design of Automated Vehicle Event Data Recorders2025-01-86784/1/2025
When vehicle accidents occur, investigators rely on event data recorders for accident investigations. However current event data recorders do not support accident investigation involving automated or self-driving vehicles when there is state information that needs to be recorded, for example ADS modes, changes in the ODD that the vehicle operates under, and the various states of vehicle features such as intelligent cruise control, automated lane changes, autonomous emergency braking, and others. In this paper, we propose a model to design new types of event data recorders that supports accident investigations involving automated vehicles when there is state information to be recorded. The model is generic enough to be adapted to any automation level and any set of automated vehicle functional features. The model has been instantiated to a specific ADAS system.
Pimentel, Juan
Decelerations for Vehicles with Anti-Lock Brake Systems (ABS) during Wet-to-Dry Transitions on Asphalt and Concrete Road Surfaces2025-01-87034/1/2025
The braking performance of newer anti-lock braking system (ABS) equipped vehicles on roads with varying wetness levels is not well studied. Two late-model ABS-equipped vehicles were used to perform ABS-engaged braking tests on dry and wet asphalt and concrete surfaces from which vehicle speed and deceleration as a function of time were calculated. Tests were initially conducted on a dry surface before a water truck distributed water onto the road to create a wet road condition. A continuous series of tests were then performed until the road dried and the cycle was repeated multiple times. Across all tests of both vehicles on both road surfaces, deceleration levels generally decreased when the road was wet and returned to dry levels only when less than 25% of the road surface remained wet. Also, wet deceleration levels were high compared to the historical values used for wet roads. These findings provide a useful and readily identifiable boundary between what can be considered a dry and wet road from the perspective of choosing a maximum deceleration level when reconstructing collisions involving ABS-equipped vehicles during ABS-enabled braking.
Miller, Ian, King, David, Siegmund, Gunter
Research on Motor Safety Monitoring Control for Powertrain Control System2025-01-85114/1/2025
The motor controller, as one of the important controllers in the electric drive system, may cause unexpected acceleration or deceleration of the vehicle by the driver due to systematic failure and random hardware failure. Conducting research on the functional safety of drive motors for new energy vehicles is of great significance for reducing the systematic failure and random hardware failure of the electric drive. This paper has carried out designs including the allowable motor torque design for safety monitoring, the motor torque prediction design for safety monitoring, the rationality judgment design of the motor torque for safety monitoring, the rationality judgment design of the motor direction for safety monitoring, the functional safety motor degradation design, and the active discharge state monitoring of the motor, so that the system can transition to a safe state when an error occurs. Among them, the motor torque prediction design for safety monitoring includes predicting the motor torque based on the current signal. The rationality judgment design of the motor torque for safety monitoring includes monitoring the allowable motor torque and the actual motor torque. The rationality judgment design of the motor direction for safety monitoring includes, by analyzing the torque and rotational speed direction of the P2 motor of the drive system and the direction of the gear lever, proposing a control strategy for rotational speed direction monitoring based on conditions such as the torque and rotational speed direction of the P2 motor, the direction of the gear lever, and the rotational speed change rate. The functional safety motor degradation design includes a method for judging the quality level of the motor torque based on the motor eddy current sensor, phase current sensor, motor temperature sensor, absolute value of the estimated motor torque.
Jing, Junchao, Zuo, Botao, Liu, Yiqiang, Huang, Weishan, Dai, Zhengxing
Modeling and Analysis of Comfort Braking Control Based on Brake-by-Wire and Active Suspension Systems10-09-02-00112/7/2025
As wire control systems advance, they have given rise to a diverse suite of advanced driver assistance services and sophisticated fusion control capabilities. This article presents an innovative strategy for achieving comfortable braking in electric vehicles, propelled by the unwavering goal of enhancing driving experience. By integrating active suspension systems with brake-by-wire technology, the approach ensures that drivers retain their confidence throughout the braking process. The brake-by-wire system adeptly discerns the driver’s braking intent through the pedal’s displacement sensor. Utilizing this technology, we have developed a pioneering function aimed at delivering comfort braking control (CBC). This function not only refines the braking experience but also solidifies the driver’s trust in the braking system. Designed to counteract the head nodding effect during vehicle deceleration, the CBC system minimizes or even eradicates the jarring sensation of pitching for both the driver and passengers. The algorithm detailed in this article has undergone rigorous validation through extensive real-world vehicle testing. The results indicate that the proposed method markedly improves key performance metrics: it enhances the pitch angle by 37.74%, reduces the pitch angle speed by 77.12%, shortens the convergence time by 57.14%, and diminishes the pitch angle peak amplitude by 45.65%, all within a 0.3g braking deceleration scenario. This groundbreaking function has now been successfully implemented in mass production vehicles.
Tian, Boshi, Li, Liang, Liao, Yinsheng, Lv, Haijun, Qu, Wenying, Hu, Zhiming, Sun, Yue
Crash Simulation of Steel-Wood Hybrid Road Safety Barrier with Perforated Post Design: TB 11 Evaluation2024-28-016212/5/2024
Research areas in Road furniture have become critical due to the rising incidence of road accidents and fatalities. Enhancing road attributes such as crash barriers, crash cushions, crash poles, and emergency communication systems can significantly reduce these fatalities. Among these, crash barriers promise particular attention as they serve as immediate safety mechanisms. When a vehicle loses control, crash barriers can effectively mitigate the severity of accidents by restraining the vehicle and preventing more severe outcomes. This paper focuses on the performance of a novel steel-wood hybrid crash barrier with perforated post parallel to vehicles direction, designed to enhance road safety in hilly areas. Utilizing finite element analysis (FEA) in LS-DYNA software, renowned for simulating structural deformation under loading, we evaluated the structural response and crashworthiness of the hybrid barrier under various impact scenarios. Our simulations assessed the barrier's effectiveness in dissipating kinetic energy and reducing vehicle deceleration during collisions, considering material properties, geometry, and impact conditions. The results provide valuable insights into the mechanical behavior and performance characteristics of the steel-wood hybrid crash barrier, informing the optimization of design parameters and the development of advanced safety features for transportation infrastructure. By combining steel and wood, this hybrid barrier aims to reduce the required working width while maintaining high safety standards, particularly in challenging terrains, thereby contributing to safer roads for all users.
Bendre, Sagar, Das, Alakendu, Jaiswal, Manish
An Economical Multilevel Backup Strategy for Electro-Hydraulic Braking System by Integrating Driving and Electronic Parking Brake Systems10-08-04-00299/24/2024
The braking system stands as a vital component within a vehicle; its malfunction has the potential to precipitate catastrophic or severe accidents. There are two primary backup strategies: one involves hardware redundancy, and the other is the optimization of software strategies in conjunction with other systems. Redundancy among various actuators of the second strategy not only maximizes the vehicle’s inherent capabilities but also results in cost savings. In this article, a multilevel backup strategy that integrates electro-hydraulic braking, driving systems, and electronic parking brake systems is explored. Utilizing a self-developed braking safety control system, a proposal is made for the electronic parking brake to participate in service braking. Additionally, two functional modules, pre-clamping and deceleration following, have been meticulously designed to tackle the challenges of response delay and insufficient control precision that are commonly associated with electronic parking brakes. The effectiveness of the backup strategy was confirmed through real-vehicle testing. The results demonstrate that this multilevel backup strategy can provide a deceleration capacity of at least 4.88 m/s2 in the worst-case scenario, which is twice the requirement set by national standards.
Tian, Boshi, Li, Liang, Liao, Yinsheng, Lv, Haijun, Wang, Xiangyu, Hu, Zhiming, Sun, Yue, Qu, Wenying
Virtual Brake Pull Maneuver Development2023-36-00211/8/2024
The Brake Pull phenomena is the directional deviation when a strong deceleration is applied, this happens due to asymmetries in the vehicle with diverse origins: dimensional, stiffness, damping, friction and loading condition. This phenomenon creates the necessity of driver inputs on the steering wheel adjusting the vehicle direction to keep the straight line. Great part of asymmetries in the vehicle is avoidable due to building quality, correct maintenance, and others. However, an unequal loading condition on the transversal direction of the vehicle is very common: the vehicle occupied only by the driver is a usual condition. This circumstance creates a load asymmetry that can induces the brake pull phenomena. This study aims to create and validate a virtual toll capable of representing the brake pull phenomena caused by a loading asymmetry. A vehicle modeled in multibody dynamics technique representing the vehicle mass inertias, suspension mechanisms kinematics, tire behavior and components dampers and stiffness is the adopted tool to represent this situation. This model will be exposed to a strong deceleration (~0.85g) and verify the brake bull measuring the yaw velocity. The yaw velocity results acquired through simulation will be compared with physical results.
Terra, Rafael Tedim
Optimization of Brake System Parameters Using Genetic Algorithm2023-01-188111/5/2023
The design of brake system specification is an iterative process, where repeated calculations need to be performed to achieve the target brake performance and finalize the system parameters. Hence there is a need for a methodology to arrive at a set of optimized brake system parameters which can in turn reduce the brake system definition time. In this paper, the brake system dynamics of a passenger/commercial vehicle is mathematically modelled (divided into two parts i) foundation brake model ii) brake apply system model) and uses genetic algorithm to optimize the system parameters. The objective function maximizes the vehicle deceleration and arrives at the target brake feel which includes brake pedal effort and brake pedal travel. When compared to conventional method of brake design which uses iterative approach, this method has the capability to arrive at the optimized results at a faster rate.
Velumani, Sivaramakrishnan, Balasubramani, Arunchandran
The Impact of Seat Belt Pretensioner Deployment on Forward-Leaning Occupants09-11-02-00199/20/2023
Pyrotechnic seat belt pretensioners typically remove 8–15 cm of belt slack and help couple an occupant to the seat. Our study investigated pretensioner deployment on forward-leaning, live volunteers. The forward-leaning position was chosen because research indicates that passengers frequently depart from a standard sitting position. Characteristics of the 3D kinematics of forward-leaning volunteers following pretensioner deployment determines if body size is correlated with subject response. Nine adult subjects (three female), ages 18–43 years old, across a wide range of body sizes (50–120 kg) were tested. The age was limited to young, active adults as pyrotechnic pretensioners can deliver a notable force to the trunk. Subjects assumed a forward-leaning position, with 26 cm between C7 and the headrest, in a laboratory setting that replicated the passenger seat of a vehicle. At an unexpected time, the pretensioner was deployed. 3D kinematics were measured through a nine-camera motion capture system with reflective markers on the left and right glabella, tragus, manubrium, C7, lateral proximal head of humerus, olecranon process, patella, and lateral malleolus. For uniformity, all pretensioners were of the same model made by Autoliv and were dual systems (having deployment in the retractor and outbound anchor). The initial velocity of the trunk (first 50 ms) was dependent on the body size, with smaller subjects getting pulled back quicker. Following the first ~160 ms, there was a slight rebound where subjects briefly moved forward, followed by a period of high intersubject variance in movement. By isolating the effects of pyrotechnic pretensioner deployment on live volunteers, this study fills in an important gap in automotive safety research and may help with evaluating computer models or designing future restraint systems with advanced sensor technology where pretensioners deploy prior to significant vehicle deceleration.
Hellenbrand, Ciboney, Brown, J. Fletcher, Goodworth, Adam
Post-Collision Run-Out Vehicle Deceleration Based on Real-World Data2023-01-50639/13/2023
In traffic accidents, the run-out is the phase after impact until reaching a final rest position. Analyzing and reconstructing this phase is a task leading sometimes to a broad bandwidth of results. This can be due to the unknown driver’s reaction and braking behavior. The well-known literature describes rollout decelerations, but these exclude the influence of the driver, particularly with regard to accident situations. Measurement data from real-world collisions can help quantifying the vehicle’s deceleration during the run-out and thus at least partially close the existing research gap. Therefore, this study deals with the systematic evaluation of real-world measurement data from intersection collisions collected by accident data recorders. The high-frequency acceleration and speed data of 45 accident vehicles with impact velocities up to 70 kph were processed for this purpose; characteristic values for the run-out phase were calculated in each case and then statistically evaluated. Results in terms of mean deceleration rates are presented as well as conclusions about driver’s post-collision behavior. On the one hand, the data reveal that it is extremely unlikely that a vehicle will not be actively braked by the driver during run-out and, on the other hand, that braking with maximum deceleration is also unlikely. The results indicate a mean resultant run-out deceleration with respect to time of 4.5 m/s2 and with respect to distance of 4.1 m/s2. This means more intensive braking by human drivers after a collision than typical deceleration in normal everyday driving activities and is comparable to intervention of advanced driver-assistance systems. These findings can assist the reconstructionist analyzing intersection accidents in quantifying or narrowing down the level of deceleration of a vehicle in run-out and for this reason the driver’s post-collision behavior.
Fuerbeth, Uwe
A Modified Enhanced Driver Model for Heavy-Duty Vehicles with Safe Deceleration2023-24-01718/28/2023
To accurately evaluate the energy consumption benefits provided by connected and automated vehicles (CAV), it is necessary to establish a reasonable baseline virtual driver, against which the improvements are quantified before field testing. Virtual driver models have been developed that mimic the real-world driver, predicting a longitudinal vehicle speed profile based on the route information and the presence of a lead vehicle. The Intelligent Driver Model (IDM) is a well-known virtual driver model which is also used in the microscopic traffic simulator, SUMO. The Enhanced Driver Model (EDM) has emerged as a notable improvement of the IDM. The EDM has been shown to accurately forecast the driver response of a passenger vehicle to urban and highway driving conditions, including the special case of approaching a signalized intersection with varying signal phases and timing. However, most of the efforts in the literature to calibrate driver models have focused on passenger vehicles. This study aims to expand the calibration of the EDM to commercial vehicle drivers, specifically those driving heavy-duty trucks. Real-world data for the calibration are collected with an onboard advanced connectivity platform that not only acquires and manages information about vehicles and routes but also provides ADAS and vehicles-to-everything (V2X) communication. Therefore, the data can be processed either on-board or on a cloud platform. Furthermore, a new mode is introduced within the EDM which enables preemptive deceleration of the vehicle when approaching an intersection, making a turn, or exiting from a highway. This effort will not only provide a baseline virtual driver to benchmark the performance of CAV technology in the commercial truck industry but will also enable the assessment of the impact of driver aggressiveness on the energy consumption of electric commercial vehicles.
Shiledar, Ankur, Villani, Manfredi, Rizzoni, Giorgio, Adinolfi, Ennio Andrea, Pandolfi, Alfonso, Paolino, Antonio, Pianese, Cesare
Model-Free Intelligent Control for Antilock Braking Systems on Rough Roads10-07-03-00175/26/2023
Advances made in advanced driver assistance systems such as antilock braking systems (ABS) have significantly improved the safety of road vehicles. ABS enhances the braking and steerability of a vehicle under severe braking conditions. However, ABS performance degrades on rough roads. This is largely due to noisy measurements, the type of ABS control algorithm used, and the excitation of complex dynamics such as higher-order tire mode shapes that are neglected in the control strategy. This study proposes a model-free intelligent control technique with no modelling constraints that can overcome these unmodelled dynamics and parametric uncertainties. The double deep Q-learning network (DDQN) algorithm with the temporal convolutional network is presented as the intelligent control algorithm. The model is initially trained with a simplified single-wheel model. The initial training data are transferred to and then enhanced using a validated full-vehicle model including a physics-based tire model, and a three-dimensional (3D) rough road profile with added stochasticity. The performance of the newly developed ABS controller is compared to a baseline algorithm tuned for rough road use. Simulation results show a generalizable and robust control algorithm that can prevent wheel lockup over rough roads without significantly deteriorating the vehicle stopping distance on smooth roads.
Abreu, Ricardo, Botha, Theunis R., Hamersma, Herman A.
Decelerations for Vehicles with Anti-lock Brake Systems (ABS) on Dry Asphalt and Concrete Road Surfaces2023-01-06164/11/2023
Anti-lock brake systems (ABS) produce high levels of vehicle deceleration under emergency braking conditions by modulating tire slip. Currently there are limited data available to quantify the mean, variance, and distribution of vehicle deceleration levels for modern ABS-equipped vehicles. We conducted braking tests using twenty (20) late-model vehicles on contiguous dry asphalt and concrete road surfaces. All vehicles were equipped with a 5th wheel sampled at 200 Hz, from which vehicle speed and deceleration as a function of time were calculated. Eighteen (18) tests were conducted for each vehicle and all tests were conducted from a targeted initial speed of 65 km/h (40 mph). Overall, we found that late-model ABS-equipped vehicles can decelerate at average levels that vary from about 0.871g to 1.081g across both surfaces, and that deceleration levels were on average about 0.042g higher on asphalt than on concrete. We also found that the passenger cars decelerated about 0.087g higher than the vans and SUVs. Data from these tests provide a technical foundation for estimating the mean, variance, and distribution of ABS braking levels.
Miller, Ian, King, David, Wilkinson, Craig, Siegmund, Gunter P.
Development of Truck Platooning System Including Emergency Braking Function with Vehicle-in-the-Loop (VIL) Testing2023-01-05714/11/2023
Platoon is a system that connects vehicles through vehicle-to-vehicle (V2V) communication technology to maintain a short distance between vehicles while driving on the road. To improve fuel efficiency, many automotive original equipment manufacturers (OEMs) are interested in developing and demonstrating real-world platoon system. However, it is hard for heavy duty trucks to develop this system due to the difficulty of maintaining the targeted intervehicle distance not only for fuel efficiency but also for safety in case of emergency braking. Because of this critical safety issue in the emergency situation, the platoon system for heavy duty trucks can be hardly demonstrated or tested in real vehicle environment. The relatively complex system and the slow response characteristic of commercial vehicles makes this even more difficult. In this paper, focusing on the emergency braking function implemented through the V2V communication interface, we introduce the platoon system developed by Hyundai Motor, and explain the system configuration, technology, and control strategy. While there have been various efforts to develop the emergency braking system of the platoon system in a simulation environment in previous studies, we conduct real vehicle-in-the-loop (VIL) test with three semi-trailer trucks. Through repeated VIL tests, we could identify certain vehicle data to be transmitted and received via V2V communication during emergency braking situation and the corresponding signals were properly tailored to reduce the inherent delay. Finally, by reducing the delay of the front vehicle’s deceleration signal, the safe distance gap between vehicles is secured even after the emergency braking. VIL test results of the system are also included to validate the effectiveness of the proposed platoon system.
Hong, Jeong-Ki, Kim, Sangjun, Lim, Jong Su, Nam, Joohan, Min, Byeonghyeok, Lee, Chanhwa
Energy Modeling of Deceleration Strategies for Electric Vehicles2023-01-03474/11/2023
Rapid adoption of battery electric vehicles means improving the energy consumption and energy efficiency of these new vehicles is a top priority. One method of accomplishing this is regenerative braking, which converts kinetic energy to electrical energy stored in the battery pack while the vehicle is decelerating. Coasting is an alternative strategy that minimizes energy consumption by decelerating the vehicle using only road load. A battery electric vehicle model is refined to assess regenerative braking, coasting, and other deceleration strategies. A road load model based on public test data calculates tractive effort requirements based on speed and acceleration. Bidirectional Willans lines are the basis of a powertrain model simulating battery energy consumption. Vehicle tractive and powertrain power are modeled backward from prescribed linear velocity curves, and the coasting trajectory is forward modeled given zero tractive power. Decel modes based on zero battery and motor power are also forward modeled. Multi-mode decel (using a low power decel mode with regenerative braking) is presented as a set of intermediate strategies. An example vehicle using these strategies is modeled in fixed-route simulations, and scoring is based on travel time, energy consumption, and bias towards minimizing one of those metrics. Regenerative braking has the lowest travel time, and coasting the lowest energy consumption, but such bias increases overall cost. Multi-mode strategies lower overall cost by balancing reductions in travel time and energy consumption. Model sensitivity to grade and accessory load fluctuation makes it adaptable to different vehicles and environments. Simulation results demonstrate how regen braking alternatives could be modeled to enhance connected and automated vehicle systems in battery electric vehicles.
Hom, William, Nelson, Douglas
Quantifying the Deceleration of Various Electric Vehicles Utilizing Regenerative Braking2023-01-06234/11/2023
Regenerative braking is present in almost all electric vehicle models and as the demand for electric vehicles grows, the types of electric vehicles grow as well. Regenerative braking allows for an electric vehicle to convert a vehicle's kinetic energy into electrical potential energy by utilizing the electric motors to slow the vehicle. This potential energy is then returned to the vehicle’s battery allowing for the vehicle’s range to be extended. The vehicles tested during the study were as follows: 2022 Rivian R1T, 2022 Tesla Model Y, 2022 Hyundai Ioniq 5, 2020 Tesla Model 3, 2021 Volkswagen ID.4, and 2021 Ford Mustang Mach-E. Although regenerative braking slows the vehicle, not all levels of regenerative braking bring the vehicle to a complete stop. The study showed that there are typically two types of regenerative braking. The first, commonly referred to as one-pedal driving, will bring a vehicle to a complete stop without the application of the brake pedal. The other slows the vehicle to a pre-determined speed before the regenerative braking is no longer applied. This type of regenerative braking allowed the vehicle to move forward, or coast, after regenerative braking was no longer applied. This study sought to determine and compare the average deceleration from regenerative braking, without applying the brake pedal, of each vehicle at all levels of regeneration. Tests were conducted at speeds of approximately 15 mph, 30 mph, 45 mph, and 60 mph. As electric vehicles introduced the ability to change the vehicles performance and driving characteristics through software updates, it may be necessary to complete testing periodically.
Vigil, Cole Mackenzie, Kaayal, Omar, Szepelak, Alexander
Evaluation of Occupant Kinematics and Kinetics during Moderate Severity Simulated Frontal Impacts with and without Frontal Airbag Deployment2023-01-05594/11/2023
Airbag and seat belt pretensioner deployment characteristics depend on multiple factors, such as the magnitude, direction, and rate of vehicle deceleration as detected by vehicle crash sensors and evaluated by vehicle-specific algorithms. Frontal airbag and pretensioner deployments are likely to be commanded during frontal crash events with high initial vehicle deceleration typically associated with high vehicle change in velocity (delta-V). However, within a range of moderate changes in vehicle speeds, referred to as the “gray zone,” a vehicle-specific algorithm may or may not command deployment depending on crash pulse parameters and occupant sensing, among other items. Publicly available testing in the moderate-speed range is lacking and would be useful to evaluate the effects of airbag and pretensioner deployment on occupant kinematics and loading. In this study, sled tests were performed using a standard passenger vehicle buck simulating frontal deceleration impact events in a “gray-zone” severity of 19 kph (12 mph) delta-V and in a typical deployment severity of 32 kph (20 mph) delta-V. Matched sled tests were performed with and without airbag deployment with instrumented Hybrid III 50th percentile anthropomorphic test devices (ATDs) properly belted in the driver and front passenger seats. Additionally, one paired test was conducted at 19 kph with and without pretensioner deployment in the presence of airbag deployment. Airbag deployment for the 19 kph delta-V tests did not significantly affect occupant kinematics or loading compared to the non-deployment tests, while some differences were apparent for the 32 kph delta-V tests. In all tests, injury metrics were well below applicable injury assessment reference values (IARVs).
Sharpe, Sarah S., Grijalva, Sandra, Allin, Leigh, Courtney, Amy, Toney-Bolger, Megan, Pokutta-Paskaleva, Anastassia, Crosby, Charles L., Carhart, Michael
Electric Motorcycle Acceleration, Braking, and Regenerative Coast-Down Deceleration Testing and Analysis2023-01-06314/11/2023
Three fully electric motorcycles were tested and analyzed for acceleration, braking, and regenerative coast-down deceleration. A Zero DSR, BMW C-Evolution, and a Harley-Davidson LiveWire underwent each of the following test series. The first test series consisted of accelerating the electric motorcycles from a stop. For the second test series, the motorcycles were decelerated by using three different brake applications: front and rear brake application, front-only brake application, and rear-only brake application. For the third test series, regenerative coast-down deceleration was tested at different ride mode configurations. Regenerative braking systems are designed to convert the vehicles’ kinetic energy into electrical potential energy during the vehicles’ coast-down phase, resulting in a moderate deceleration. In addition to testing the vehicles’ deceleration during its’ regenerative coast-down phase, brake light activation delay relative to throttle roll-off was analyzed. All motorcycles were tested on factory available ride mode configurations (Zero: Eco and Sport, BMW: Eco Pro, Dynamic, Road, and Sail, Harley-Davidson: Range, Street, Rain, and Sport). Each motorcycle was instrumented with a VBOX 3i with NTRIP (Networked Transport of RTCM via Internet Protocol) RTK (Real-time kinematic positioning) accuracy to measure and document vehicle speed. The electric motorcycles tested produced a 0 – 60 mph acceleration range of 0.29 – 0.77 g. Average acceleration for all tested motorcycles and all modes available was calculated to be 0.53 g. For the braking test series including front and rear brake application, front-only, and rear-only brake application, the electric motorcycles braked at a deceleration range of 0.30 – 0.86 g. Average brake deceleration for all tested motorcycles and available ride modes was calculated to be 0.59 g. During the regenerative coast-down deceleration test series, the electric motorcycles decelerated at a range of 0.10 – 0.33 g. Average regenerative braking of all tested electric motorcycles and available modes was calculated to be 0.15 g. Brake light activation delay relative to accelerator throttle roll-off ranged from 0.05 – 1.1 sec. Average brake light activation delay was calculated to be 0.31 seconds relative to throttle roll-off. The results of this study will provide insight for accident reconstructionist to characterize acceleration, braking, and regenerative coast-down deceleration capabilities for the following electric motorcycles: Zero DSR, BMW C-Evolution, and Harley-Davidson LiveWire.
Phan, Chris, Meza Buendia, Saul A., Nguyen, Benjamin Mai, Fatzinger, Edward, Landerville, Jon
Forward Collision Warning and Automatic Emergency Braking Test Procedure and Minimum Performance Requirements - Truck and BusJ3029_202301 (Current)1/17/2023
This SAE Recommended Practice (RP) establishes uniform powered vehicle-level test procedure for forward collision warning (FCW) and automatic emergency braking (AEB) used in trucks and buses greater than 10000 pounds (4535 kg) GVWR equipped with pneumatic brake systems for detecting, warning, and avoiding potential collisions. This RP does not apply to electric powered vehicles, trailers, dollies, etc., and does not intend to exclude any particular system or sensor technology. These FCW/AEB systems utilize various methodologies to identify, track, and communicate data/information to the operator and vehicle systems to warn, intervene, and/or mitigate in the momentary longitudinal control of the vehicle. This specification will test the functionality of the FCW/AEB (e.g., ability to detect objects in front of the vehicle), its ability to indicate FCW/AEB engagement and disengagement, the ability of the FCW/AEB to notify the human machine interface (HMI) or vehicle control system that an object is detected under specified operating and environmental conditions, and the ability of the AEB to decelerate the vehicle to avoid impact or reduce the severity of the impact should the human operator not respond. This specification does not define tests for all possible operating and environmental conditions. The HMI is not addressed in this document.
Truck and Bus Automation Safety Committee
Braking Dynamics of Auto-Rickshaw2022-28-038210/5/2022
Auto-rickshaw is one of the most customary modes of transport in urban as well as rural areas of India. The safety of this vehicle is of prime concern. The braking system plays a vital role in the safety of any vehicle. This work is carried out in order to analyze the vehicle behavior during braking maneuver since the literature survey carried out had fewer details about the braking performance of Auto-rickshaw. Bajaj RE was chosen in particular for our study because it is widely used. Stopping distance analysis is utilized in order to estimate the vehicle braking performance. The straight-line braking performance is studied with the help of a 3-DOF mathematical model of the vehicle developed which includes the surge, heave and pitch motions. This model is formulated based on the Newtonian approach and is built on Simulink environment. The complete brake system is developed and coupled with the mathematical model. The Pacejka tire model is implemented in order to obtain accurate results. The vehicle parameters such as C.G. location and inertia were obtained experimentally and passed into the model. The inputs provided to the model are initial vehicle velocity, pedal force and loading conditions. The simulation results include vehicle deceleration, velocity, stopping distance, pitching of the vehicle, etc. In order to validate the results obtained through simulation, experimental analysis is performed with the help of VBOX Test Suite. The test results comprise vehicle velocity and distance covered. The simulation and test results are compared for different input conditions and discussed. For a minute variation in MFDD, the variation in simulation and test results were very close i.e., for distance travelled and time taken were respectively -0.25% and 3.34%. A particular scenario was simulated and validated with standards [7].
M H, Akshith, Anand, Srijan, Chakravarthy, Raghav, N H, Hemanth, Patil, Sharanbasappa
Estimation Parameters of Braking of Vehicles Category M1 at Definition of Circumstances Road Accidents2022-01-11669/19/2022
The study of the distribution of the deceleration of vehicles of category M1 when performing various maneuvers is intended to develop methods for assessing the parameters of maneuvering of cars in the study of the circumstances of the occurrence of road accidents. Experimental studies were carried out on passenger cars, which are equipped with automated braking force control systems, for various driving styles. M1 category vehicles were maneuvered on dry asphalt pavement in the range of speeds from 11 to 25 m / s, which is typical for most road traffic accidents. It was found that when braking a vehicle of category M1, longitudinal deceleration increase according to a second-order polynomial dependence in the range of deceleration variation from 1.39 to 5.86 m/s2. This fact is well explained by the peculiarities of the operation of automated brake force control systems that are equipped a vehicle and the psychological behavior of the driver, who carries out the process of braking the vehicle before the occurrence of the road traffic accident. It has been established that the vehicle deceleration may differ by 50-55% from the vehicle deceleration value obtained during its emergency braking in conditions not leading to a road traffic accident. The study showed that the presence in the design of a modern vehicle of category M1 of automated systems for regulating the braking force makes it possible to expand the range of its possible lateral displacements up to 65%, change the heading angle up to 82% and reduce the required longitudinal distance for maneuvering the vehicle by 25%, while maintaining stability vehicle movement.
Kashkanov, Andrii, Kashkanova, Anastasiia, Podrigalo, Mikhail, Klets, Dmytro, Saraiev, Oleksii, Mikhalevich, Mykola, Andrey, Korobko
Decelerations of Capsized Motorcycles - An Update2022-01-08233/29/2022
Many motorcycle crashes involve the motorcycle capsizing, impacting the ground, and sliding on the road surface. When performing speed calculations, the energy or speed loss for the ground impact and sliding phases may need to be calculated. To perform these calculations, the reconstructionist will typically determine the slide distance based on the physical evidence and then apply a range of decelerations over that distance based on test data in the literature. Decelerations can be selected for motorcycles with similar characteristics (crash bars, panniers, fairings, etc.) sliding on similar surfaces (asphalt, concrete, dirt, gravel, etc.). This approach is adequate but sometimes results in a wide range due to the variability in reported decelerations in prior studies. It could be helpful to narrow the likely range of decelerations, and thus, the speed range. Many past studies, however, describe their tests with inadequate detail to parse out precisely what factors were most influential in producing the reported decelerations. The present study reports four additional motorcycle drop and slide tests, attempting in the process to lay out a model for how future tests could be reported such that influential factors could be identified. In addition, this test series included a motorcycle with crash bars. This motorcycle was tested twice with the crash bars. Then the crash bars were removed, and the motorcycle was tested again. These tests involved the motorcycle experiencing more significant impacts with the ground than prior tests involving motorcycles with crash bars.
Rose, Nathan, Palmer, Jacob, Smith, Connor, Carter, Neal, Walter, Kevin
New Metrics for Quantifying the Energy Efficiency of Platoons in the Presence of Disturbances2022-01-05263/29/2022
Due to aerodynamic drag reduction, vehicles may have significant energy savings while platooning in close succession. However, when circumstances force active deceleration to maintain the platoon, such as during vehicle cut-ins or grade changes, the aerodynamic efficiency benefits may be undermined by losses in kinetic energy. In this work, a theoretical relationship is derived to correlate the amount of active deceleration a vehicle experiences with energy efficiency. The derived relationship is leveraged to analyze platooning data from the last vehicle in a class 8 vehicle platoon. The data include both two- and four-truck platoons operating under nine different truck-to-truck gap control strategies. Using J1939 CAN data and GPS-estimated grade profiles, off-throttle data were isolated and longitudinal acceleration is estimated as a function of grade using Kalman filtering. Using bounding regions to isolate coasting data from active deceleration data, the active deceleration losses were correlated to the energy consumption of the platooning vehicle. For the best correlated method, it was found that every kJ/kg·hr of active deceleration increased the platoon energy consumption by 9.09±0.59%, with an adjusted R2 of 0.874. Suggestions for application of the method to platoons are made, and future work is discussed.
Stegner, Evan, Snitzer, Philip, Bevly, David, Hoffman, Mark
Research on Hierarchical Control of Automobile Automatic Emergency Braking System Based on V2V2021-01-702512/15/2021
In order to ensure braking efficiency and improve the comfort of drivers and passengers, a two-stage braking grading control system was proposed. In the upper controller, the enhanced time-to-collision model under different working conditions was designed, and the braking threshold was determined considering the comfort of braking drivers and passengers, and the driver’s braking behavior was analyzed to determine the vehicle braking deceleration. The vehicle longitudinal dynamic model was built in the lower layer, the PID controller was used to reduce the model deviation. This paper improves the test standard on the basis of China-New Car Assessment Program. The results show that the remaining relative distance between the two vehicles was in the safe range. The control strategy can achieve collision avoidance of vehicle emergency braking.
ZHANG, Senlin, OU, Jian, DENG, Guohong, XU, Ze
Research on Trajectory Planning and Tracking Strategy of Lane-changing and Overtaking based on PI-MPC Dual Controllers2021-01-126210/11/2021
Aiming at the problem of poor robustness after the combination of lateral kinematics control and lateral dynamics control when an autonomous vehicle decelerates and changes lanes to overtake at a certain distance. This paper proposes a trajectory determination and tracking control method based on a PI-MPC dual algorithm controller. To describe the longitudinal deceleration that satisfies the lateral acceleration limit during a certain distance of lane change, firstly, a fifth-order polynomial and a uniform deceleration motion formula are established to express the lateral and longitudinal displacements, and a model prediction controller (MPC) is used to output the front wheel rotation angle. Through the dynamic formula and the speed proportional-integral (PI) controller to control and adjust the brake pressure. Based on simulation to optimize the best lane change completion time coefficient at different longitudinal lane change speeds, the relationship between the vehicle collision avoidance stable lane change time and the real-time vehicle speed and deceleration is obtained, then it is optimized by neural network algorithm, to avoid the vehicle collision avoidance and deceleration change unstable performance such as rollover occurred during the road. Finally, the simulation verification of the deceleration and lane changing to overtake conditions at a certain initial vehicle speed shows that the maximum lateral acceleration is 3.03m/s2, and the error from the maximum allowable acceleration is 1%. The maximum error of the yaw angle is 0.8°, and the maximum lateral acceleration is 3.22m/s2 and 3.16m/s2 respectively, which does not exceed the allowable acceleration of 4m/s2, which satisfies the lateral stability of the vehicle. Therefore, in the study of trajectory planning and tracking control of autonomous vehicles, the controller can improve the control robustness of decelerating and changing lanes.
Yin, Jian, Chen, Xu Jia, Zu, Bingfeng, Xu, Yuliang, Zhou, Jianwei
Detailed Modeling of Pneumatic Braking in Long Combination Vehicles02-14-03-00208/23/2021
A detailed model for pneumatic S-cam drum brake systems is developed and integrated into a multibody dynamic model for a 33-ft A-double long combination vehicle (LCV). The model, developed in TruckSim®, is used to study the dynamics of LCVs during straight-line braking at various speeds. It includes the response delay in braking that occurs from the time of application to when the brakes are applied at the drum for all axles. Additionally, the model incorporates an accurate characterization of brake torque versus chamber pressure at different speeds, along with the anti-lock brake system (ABS) dynamics, to yield an accurate prediction of the vehicle’s deceleration during braking. The modeling results are compared with test results at speeds ranging from 20 mph to 65 mph on dry pavement. A close match between the model’s prediction and test results is observed. The model is then used to perform a parametric study that evaluates braking distance and time for different pavement coefficients of friction (μp) at various speeds. The results indicate a distinct nonlinear relationship between μp and braking dynamics. At various μp, stopping time increases linearly with speed, as perhaps expected. Stopping distance, however, increases nonlinearly for a larger μp and linearly for a smaller μp versus speed. At a given speed, stopping time increases nonlinearly with a reduced μp, whereas stopping distance increases relatively linearly with a reduced μp.
Zhang, Zichen, Sun, Nan, Chen, Yang, Ahmadian, Mehdi
Performance of the Ford Pre-Collision Assist with Automatic Emergency Braking System in Instrumented Tests2021-01-08944/6/2021
Modern Ford vehicles can be manufactured with a system known as Pre-Collision Assist with Automatic Emergency Braking (AEB). The Pre-Collision Assist feature uses camera technology to detect a potential collision with a vehicle or pedestrian directly ahead. If a potential collision is detected, an alert sound is emitted, and a warning message displays in the vehicle’s message center. If the driver response is not sufficient, AEB will be pre-charged and brake-assist sensitivity will be increased to provide full responsiveness if the driver does brake. If there is no perceived corrective action and a collision is imminent, the vehicle’s brakes can apply automatically. By detecting the possible collision and actuating the braking system, it is possible to prevent some collisions and lessen the severity of others. Testing of this system was conducted using a 2020 Ford Explorer. During several tests, the instrumented Ford was driven at a simulated target vehicle or pedestrian dummy. Data were collected to determine at what range the system activated, the closing speeds at which the system prevented a collision, the vehicle deceleration rate resulting from system activation, and the behavior of the system when there was some driver intervention.
Vandiver, Wesley, Anderson, Robert
Intelligent Deceleration Energy-Saving Control Strategy for Electric Vehicle2021-01-01234/6/2021
In order to improve the vehicle economy of electric vehicles, this paper first analyzes the energy-saving mechanism of electric vehicles. Taking the energy consumption of the deceleration process as a starting point, this paper deeply analyzes the energy consumption of the deceleration process under several different control modes by the test data, so as to obtain two principles that should be followed in energy-saving control strategy. Then, an intelligent deceleration energy-saving control strategy by getting the forward vehicle information is developed. The overall architecture of the control strategy consists of three parts: information processing, target calculation and torque control. The first part is mainly to obtain the forward vehicle information from the perception systems, and the user's habits information from big data, and this information is processed for the next part. The second part mainly determines the entry and exit timing of the intelligent deceleration energy-saving control function, and calculates the target deceleration at the same time. The third part is to use PID control algorithm to control the torque, and filter the torque when the function enters and exits. Finally, the function test and road test have been carried out on an electric vehicle, and the results show that the proposed intelligent deceleration energy-saving control strategy can realize automatic deceleration control. And considering the driver's daily driving habits, it could better meet the deceleration expectations of drivers. This automatic control can improve vehicle economy and reduce fatigue caused by frequent braking during driving.
Zhao, Yongqiang, Zhang, Qiang, Pang, Erchao, Li, Jun, Jiankang, Liu
Objectified Drivability Analysis and Evaluation of Deceleration Maneuvers for Electric Vehicles03-14-03-00232/15/2021
Objectified analysis and evaluation tools offer cost- as well as time-saving potentials regarding the calibration process of vehicle control units. To reduce the time required for the calibration effort, standardized processes including the frontloading of development tasks enable swift calibration procedures and can be used to develop a basis for the comparison of different vehicles and also the calibration quality. In this environment, objectified evaluation methods are also being developed for the investigation of the drivability of electric vehicles. This article presents a methodology for assessing the longitudinal drive behavior of battery electric vehicles during deceleration maneuvers. The aim is to objectively evaluate the vehicle deceleration by means of reproducible driving maneuvers. In addition to further measurement signals, the longitudinal acceleration signal serves as the main evaluation basis. Based on characteristic points during the event, the deceleration maneuver is divided into sectors, which is fundamental for further evaluation. Within these sectors, corresponding objective criteria are determined, which describe the behavior of the vehicle during deceleration. Regardless of the sectors, the calculated and determined values are used to evaluate the entire driving maneuver. The determined surrogate parameters allow an objective evaluation of the subjective “drivability” and target-oriented monitoring of the objectives in the development process. The newly developed methodology is explained in detail in this article and compared with real measured validation data from different electric vehicles.
Ossendorff, Dominik, Heusch, Christian, Tatas, Lauritz, Wick, Maximilian Kurt, Birmes, Georg
Management and Control of Connected and Automated Vehicle Platoon in the Process of Variable Speed Driving, Vehicle Cut-Out or Cut-In2020-01-522012/30/2020
The Connected and Automated Vehicle (CAV) platoon can run at the speed limit and the minimum safe time gap, that is, each vehicle speed is the speed limit and the time gap between adjacent vehicles is the minimum safe time gap known as constant time gap (CTG) strategy, and the platoon will reach the high traffic efficiency. This paper aims at the three situations of variable speed driving, vehicle cut-out and cut-in of the CAV platoon, proposes the methods of CAVs management and control to ensure the efficiency and stability of the CAV platoon in the process of driving using a small number of adjusting parameters. The communication delays among vehicles are considered, the simulation experiments show that the impact of the communication delay (50-200 ms) during acceleration or deceleration is very small, and then this paper adopts the communication delay of 100 ms. The control methods take the minimum safe time gap as the goal, by controlling the acceleration or deceleration of each vehicle, so that the platoon can change speed to the new speed limit within short time while keeping the minimum safe time gap all the time. When there is a presence of cut-out or cut-in movement in the platoon, the platoon can recover to the original driving state as soon as possible using corresponding three or two adjusting parameters to control the acceleration or deceleration of vehicles, and drive at the speed limit and the minimum safe time gap again. The simulation results indicate that the control methods can make the platoon reach the new speed limit or recover the original driving state from cut-out or cut-in movement quickly and smoothly, and can effectively reduce the traffic disturbance caused by cut-out or cut-in vehicle, and improve the traffic flow.
Wang, Fujian, Dai, Hongliang, Lu, Yixiao, Han, Haihang
A New Approach of Antiskid Braking System (ABS) via Disk Pad Position Control (PPC) Method02-14-01-000410/15/2020
A classical antiskid brake system (ABS) is typically used to control the brake fluid pressure by creating repeated cycles of decreasing and increasing brake force to avoid wheel locking, causing the fluctuation of the brake hydraulic pressure and resulting in vibration during wheel rotation. This article proposes a new approach of skid control for ABS by controlling the disk pad position. This new approach involves using a modest control method to determine the optimal skid that allows the wheel to exert maximum friction force for decelerating the vehicle by shifting the brake pad position instead of modulating the brake fluid pressure. This pad position control (PPC) method works in a continuous manner. Therefore, no rapid changes are required in the brake pressure and wheel rotation speed. To identify the PPC braking performance, braking test simulations and experiments have been carried out. The optimal pad position was calculated by estimating the friction coefficient, in which the wheel skid was maintained in range. Different initial velocities and road conditions were used to study the braking behavior. Furthermore, the experimental results obtained using the PPC method, an ABS, and the conventional braking method in a braking test simulator were compared. Results show that the PPC method exhibited a suitable performance for wheel lock-up prevention. A significant reduction was obtained in the brake fluid oscillation and braking distance with the PPC method. Thus, the PPC method is a method suitable for controlling the wheel skid with limited vibration. This method is applicable to autonomous or electric cars because of the influence of voltage fluctuation on the motor-drive avoidance.
Ismail, Hasan, Chieng, Wei-Hua, Jeng, Shyr-Long
Simulation of the Combined Braking Control System for Hybrid Electric Vehicles2020-01-02174/14/2020
Simulation model of the combined braking control system for hybrid electric vehicles is proposed. The model shows working processes of the braking system with actuating friction mechanisms and an electro-hydraulic drive and regenerative braking system with an electrodynamic mechanism. The electrodynamic mechanism of regenerative braking is formed by switching the traction motor to the generator operating mode. At the same time braking effect is transmitted through the transmission to the drive wheels. The combined control of two brake systems of an electric vehicle is carried out by the driver when acting on one common control element - the brake pedal. Pushing on the braking pedal, driver generates the given control signal- desirable level of electric vehicle deceleration. In accordance with the given control signal, the law of control can be selected in the simulation model - the control function (electric vehicle deceleration) is proportional to the pedal effort or the control function is proportional to the set value of deceleration. In this case, the control system is adaptive and corrects the control signal in accordance with the control function. The control signal is applied simultaneously to the regenerative brake system and to the electro-hydraulic braking drive of the friction brake mechanisms. But at first the regenerative brake system is triggered, due to the higher working operation speed. The deceleration generated in this case is compared with the value set by the driver. If the potential of electrodynamic braking provides for electric vehicle the set value of deceleration, then the friction brake mechanisms do not turn on. Electric vehicle speed change causes a change of the electrodynamic braking potential ability. When the potential of electrodynamic braking becomes less than the value set by the driver and the controlled deceleration decreases, the friction mechanisms are activated.
Shuklynov, Serhii, Kholodov, Mykhailo, Verbitskiy, Victor, Makarov, Volodymyr, Ryzhykh, Leonid
Coasting Technology for Real-World Fuel Economy Improvement of a Hybrid Vehicle2020-01-11954/14/2020
Automobile manufactures need to adopt new technologies to meet global CO2 (carbon dioxide) emission regulations and better fuel efficiency demands from customers. Also, the production cost should be as low as possible for an affordable vehicle. Therefore, it is advantageous for OEMs to develop fuel efficient technologies which can be controlled by software without additional hardware costs. The coasting control is a fuel efficiency improvement technology that can be implemented by the change of vehicle software only. The coasting control is a technology that reduces the driving resistance (Deceleration) when the driver releases the gas pedal. This technology leads to reducing the energy required for the vehicle to drive and results in improving the real-world fuel economy. In an internal combustion engine (ICE) vehicle, the coasting state is achieved by changing the gear to neutral, and the effect has been discussed and clarified by many previous studies. On the other hand, in the coasting state of a hybrid vehicle, the regenerative energy to the motor is reduced while the driver releases the gas pedal. The coasting control of a hybrid vehicle tends to be perceived as deteriorating the fuel efficiency because the regenerative energy decreases. In this study, relations of the vehicle deceleration and the fuel economy (vehicle energy consumption) of a hybrid vehicle were studied quantitatively. In addition, we confirmed that the coasting technology was effective to improve fuel economy (reducing CO2) based on the real-world big data.
Yamaguchi, Tomoya
Energy-Optimal Deceleration Planning System for Regenerative Braking of Electrified Vehicles with Connectivity and Automation2020-01-05824/14/2020
This paper presents an energy-optimal deceleration planning system (EDPS) to maximize regenerative energy for electrified vehicles on deceleration events perceived by map and navigation information, machine vision and connected communication. The optimization range for EDPS is restricted within an upcoming deceleration event rather than the entire routes while in real time considering preceding vehicles. A practical force balance relationship based on an electrified powertrain is explicitly utilized for building a cost function of the associated optimal control problem. The optimal inputs are parameterized on each computation node from a set of available deceleration profiles resulting from a deceleration time model which are configured by real-world test drivings. Also, to maximize energy recuperation and avoid front collision and jittering, the proposed EDPS uses a hierarchical control architecture with two layers: long-sighted planning system considering the entire scope of deceleration events and real-time replanning system considering the run-time look-ahead information. Experiments which are based on a real-world driving data obtained from a plug-in hybrid vehicle (PHEV) indicate that the regenerative energy of EDPS has been improved over average 33 % when comparing to the existing system driven by a human driver without connectivity and automation benefits, and the results also show that EDPS generates feasible deceleration profiles.
Kim, Dohee, Eo, Jeong Soo, Kim, Yeojun, Guanetti, Jacopo, Miller, Ryan, Borrelli, Francesco
Study on Vehicle Spin Tendency during Braking on Differential mu Surfaces in Four Wheeled Automobile Vehicle2019-01-21149/15/2019
A four-wheeled automobile during braking event in which left and right wheels of the vehicle are on different mu surfaces, has high chances of experiencing spin, which may lead to stability issues on vehicle. This paper intends to provide a mathematical approach to predict the deceleration at which vehicle will spin during braking in a differential mu surface, and determine the effect of influencing parameters on the extent of the vehicle spin tendency. This paper also provides a correlation between theoretical vs actual decelerations for vehicles to exhibit vehicle spin tendency. This paper helps in providing sufficient aid/tool for system designer to predetermine the vehicle spin at early level of system designs and make necessary amendments at initial stage of prototype development rather than late changes, to create a product which gives safe driving experience.
Nedunuri, Kartheek, K, Rajakumar, Lalasure, Santosh
Increase of Stability for Motor Cars in Service Braking2018-01-188010/5/2018
New solutions for actual problems of determination the efficient distribution of braking forces between the axles of the vehicle, and the stability and drivability of two-axles vehicles at service braking are received in the thesis. It permitted for the first time to determine the Law of distribution of the braking forces between the axles, that ensuring straight-running stability of two-axle vehicle at service braking, to obtain the ideal characteristics for the braking system of two-axle vehicle at service braking and to determine possible values for the distribution of braking force on the front axle. The drivability criterion at service braking obtained further development; it is offered to use boundary at gripping front or rear wheels angular vehicle acceleration on the road. The application of the stability coefficient as one of the criteria for service braking efficiency allowed to determine the ideal, as for preserving the road-holding ability, Law of distribution of the braking forces between the axles. Despite the idea, if the vehicle deceleration is increased at service braking, the ideal coefficient of braking force distribution on the front axle should be decreased, but not be increased. At small decelerations, the given coefficient can be equal to one (rear wheels are not braked), and at the maximum decelerations - we should take into account the values that correspond to retain the front and rear wheels on the blocking limit. The area of rational values of the coefficient of braking force distribution on the front axle, limited by the curves of the ideal distribution of braking forces at service braking and limit values of the adhesion coefficient, and by straight line of the ideal distribution of braking forces at emergency braking are determined. The limit values of the vehicle deceleration at service braking are determined. If the limit values are lower than the given ones, it is necessary to carry out braking only with the front wheels brakes. The obtained ideal characteristics of the two-axles braking system allow to estimate braking dynamics at emergency and service braking on roads with different coefficient of adhesion. With constant distribution of braking forces between the axles the deceleration area boundaries in which the vehicle can retain the road-holding ability at service braking are defined. To assess the impact of disturbances on the road-holding ability of the vehicle at service braking, a new criterion, the coefficient of disturbing action is offered. If the criterion value does not exceed the stability coefficient, the vehicle is stable, otherwise it loses its stability.
Podrigalo, Mikhail, Turenko, Anatoliy, Bogomolov, Viktor, Klets, Dmytro, Sergiyenko, Oleg, Karpenko, Volodymyr, Gritsuk, Igor V., Turenko, Oleksandr, Korobko, Andrii, Bulgakov, Nickolay, Boboshko, Oleksandr
A Mathematical Model of the Braking Dynamics of a Car2018-01-189310/5/2018
The braking efficiency of a vehicle is its most important operational property. However, in practice, researchers utilize simplistic physical-mathematical models for the process of vehicle braking that leads to accuracy reduction of these models predictions. The literature data show that the error in assessing braking efficiency can reach 30%. One of the main indicators of the efficiency of a braking system is deceleration. Most accurately, this value can be determined by experimental measurements. However, this is not always possible due to various technical reasons. The existing models typically ignore the impact of the car design and its speed on deceleration. They also either neglect air resistance completely or account only for its horizontal component. This paper presents an improved mathematical model written in the differential form that takes into account the impact of the lifting or downforce components of the aerodynamic forces. The proposed model accounts for the dependence of car wheels adhesion with a road surface on the vehicle’s speed. Model analysis and computation showed that all these factors improve braking performance of the car. Thus far, vehicle deceleration was represented by a discrete set of points obtained experimentally. The model proposed in the paper represents vehicle deceleration as a non-linear function of time, which is a solution to some differential equation. Numerical experimental studies conducted to validate this model demonstrate its efficiency. Results of this study can be used in enhancing the braking system of a vehicle, investigating traffic accidents, and also designing or improving racecars.
Saraiev, Olexii, Gorb, Yuliya
Maximizing Coasting of 48 V Vehicles with Cold-Storage Evaporator2018-37-00235/30/2018
One of the main features of 48 V vehicles is the ability to coast at high speeds with the Internal Combustion Engine (ICE) off. This can be realized due to the high torque and power the 48 V motor-generator provides which allows a quick and smooth re-cranking of the ICE. The coasting feature reduces the fuel consumption depending on frequency and duration of the coasting events. This depends in turn on driving pattern, driving style, State-of-Charge of the 48 V and 12 V batteries and the air-conditioning (A/C) system. In summer, if the A/C runs with a mechanical belt-driven compressor, the cabin inlet air temperature from the evaporator inevitably increases during each coasting event as the ICE turns off and cannot operate the compressor. If the evaporator temperature reaches a certain threshold at which the cabin comfort is noticeably affected, the ICE is re-cranked for resuming air-conditioning. This operation during vehicle deceleration and vehicle standstill is inefficient as fuel is consumed solely for operating the A/C. Therefore, it is beneficial for fuel consumption if the evaporator maintains low temperature for long time during coasting with ICE off. One way to overcome this is to use an electrical compressor independently operated from the powertrain. However, this is a cost intensive solution, due to higher cost of electrical compressors and increased capacity of the 48 V battery required for the additional A/C supply. A more cost-effective solution is to use Phase-Change-Materials (PCM) with high thermal capacity and specified melting temperature optimized for this purpose. DENSO has developed an evaporator with modular concept to integrate PCM-filled tanks, referred to as cold-storage (CS-evaporator), which is specifically designed to maximize coasting duration of 48 V vehicles. Tests show that a fuel consumption reduction of around 5% is possible at 30 °C ambient temperature.
Özbek, Markus, Nishida, Shin, Biglia, Matteo, Kohli, Vipul, Inaba, Atsushi, Györög, Tibor, Nishikawa PhD, Michio
Investigating Steady-State Road Load Determination Methods for Electrified Vehicles and Coordinated Driving (Platooning)2018-01-06494/3/2018
Reductions in vehicle drive losses are as important to improving fuel economy as increases in powertrain efficiencies. In order to measure vehicle fuel economy, chassis dynamometer testing relies on accurate road load determinations. Road load is currently determined (with some exceptions) using established test track coastdown testing procedures. Because new vehicle technologies and usage cases challenge the accuracy and applicability of these procedures, on-road experiments were conducted using axle torque sensors to address the suitability of the test procedures in determining vehicle road loads in specific cases. Whereas coastdown testing can use vehicle deceleration to determine load, steady-state testing can offer advantages in validating road load coefficients for vehicles with no mechanical neutral gear (such as plug-in hybrid and electric vehicles). Steady-state testing may also be the only way to directly evaluate vehicle loads during coordinated driving (platooning or automated cruise control). Several electrified test vehicles with axle torque sensors were tested on a flat, level stretch of pavement to (1) validate/compare to conventional coastdown testing loads, and (2) investigate road load reductions from two-car platooning for the front and rear vehicles at varied following distances. Results show that steady-state testing provides a suitable alternative to coastdown procedures, while test data suggest that a two car on-road platooning scenario offers a potential 15% reduction in road load following at close distances.
Duoba, Michael, Jehlik, Forrest
Iterative Analysis of Free Acceleration on a Ramp and Free Deceleration (Coast-Down) on a Flat Road for Evaluating Longitudinal Dynamics Parameters of Vehicles2017-36-013111/7/2017
Aiming to find the rotational inertias, the rolling resistance coefficient and the drag coefficient of an electric vehicle, a set of tests was developed based on the speed over time curves in two conditions: free acceleration on a ramp and free deceleration (coast-down) on a flat road. Since the main interest was in knowing the parameters and not only finding the resistance power for different speeds, as is usually the case for a coast-down test, an iterative analysis of both data sets was made. The methodology was validated by testing and analyzing road vehicles, because the values of the parameters were readily available, and by confronting the results of simulations for both types of tests. For the electric vehicle, redundancies and variations were used during testing for validation. The results for the road vehicles were within a margin of up to 10.4% from the reference values.
Carioni, Leonardo Porto, Hoeltgebaum, Thiago, Chierighini, Thiago
Coast Down Curve Computational Modeling and Its Influence on Urban and Highway Autonomy Results2017-36-031911/7/2017
Currently, fuels development is strongly dependent on experiments. New engines and vehicles simulation methodologies contribute to speed up R & D projects deadlines, as well as reducing costs. This paper presents a modeling methodology for a vehicle deceleration load curve (coast down) prediction and simulations of coast down variations impact on urban and highway autonomies. Two coast down curve mathematical models were successfully developed and validated. The first one, based on vehicles technical specifications and empirical equations, resulted in percent differences up to 9% compared to the experimental results. This is lower than the variation established on coast down standard, which is 15%. The second, generated by regression analysis between other vehicles characteristics versus experimental results of F0 and F2 (coast down curve parameters), resulted in percent differences up to 15%, for six of the eight vehicles. A simulator of urban and highway autonomies as coast down load functions was successfully implemented. Their results presented differences of up to 1% compared to the experiments. The models and simulations presented in this paper show potential to decrease coast down and autonomies experimental tests, which require considerable human and material resources. In addition, coast down models may compensate the low coast down tracks tests availability. Their results could be used when it is not possible perform track tests.
Villela, Antonio Carlos Scardini, de Carvalho, Rogério Nascimento
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