Browse Topic: Brake torque

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On Natural Gas Combustion Split into Diesel Like Architecture of a Compression Ignition Engine Retrofitted for Spark Ignition Operation2026-37-00296/9/2026
In commercial areas that no longer favor diesel engines, such as Europe, it might be interesting to convert an existing compression ignition engine to the spark ignition operation and to use natural gas (NG) because of its advantages: availability of still abundant supplies worldwide and environmental benefits compared to conventional liquid fossil fuels. This paper first presents experimental results on NG combustion inside such a converted engine with diesel-like architecture dedicated to light-duty vehicles and passenger cars. Particularly, our study carried out at the engine test bed revealed that in certain operating points (low speed and load, stoichiometric mixture and rather high spark advance), the combustion is split into two distinct events (first, a fast combustion inside the cylinder and piston bowl and then, a slower combustion occurring outside the bowl-in combustion chamber, in other words, in the squish region), which is not specific to the standard spark ignition engine. This is clearly illustrated by a rate of heat release profile with two peaks. The explanations for such combustion event are also supported by a 3D CFD study showing the in-cylinder NG distribution. The combination of experimental and numerical investigations contributes to the understanding of NG combustion in the diesel like architecture of the converted CI engine when subjected to deliberately extreme conditions, namely non-optimal spark advance setting exceeding the maximum brake torque spark advance.
Clenci, Adrian F., Popa, Robert, Berquez, Julien, Iorga-Siman, Victor, Magheru, Catalin, Punov, Plamen, Niculescu, Rodica
Technical Outlook on the Potential of HVO and Biodiesel Blends for Cleaner Combustion2026-01-03164/7/2026
The increasing need to decarbonize the transport sector is accelerating the adoption of renewable and low-carbon fuels such as Hydrotreated Vegetable Oil (HVO) and biodiesel as sustainable substitutes for fossil diesel. These fuels are evaluated as drop-in solutions requiring no engine recalibration, enabling immediate GHG emission reduction in existing diesel fleets. This study experimentally investigates the combustion, performance, and emission characteristics of a turbocharged common-rail two-cylinder diesel engine (Kohler LWD 442 CRS) operated with conventional fossil Diesel, pure HVO (Hydrotreated Vegetable Oil), and an HVOB20 blend (80% HVO and 20% biodiesel produced from waste cooking oil and animal fats). Tests were carried out under steady-state conditions at the DIIEM Engine Laboratory of Roma Tre University. The analysis focused on in-cylinder pressure evolution, brake power, brake specific fuel consumption (BSFC), and both regulated and unregulated emissions. Regulated species include carbon monoxide (CO), nitrogen oxides (NOₓ) and particulate number concentration (PNC > 23 nm, PMP-compliant), while unregulated emissions cover non-methane hydrocarbons (NMHC), formaldehyde (HCHO), nitrous oxide (N₂O). CO and NMHC are key indicators of incomplete combustion: CO results from partial oxidation of carbon during fuel burning, and NMHC represents the fraction of unburned hydrocarbons excluding methane. Both pollutants decreased markedly with renewable fuels, indicating a more complete oxidation process promoted by HVO’s paraffinic composition and FAME’s oxygenated nature. Experimental results show that HVO and HVOB20 slightly increase brake torque and reduce BSFC compared with fossil diesel, despite their lower density and heating value. Combustion remained stable across all operating conditions, with negligible variations in ignition delay and pressure rise rate. NOₓ emissions were comparable or marginally higher at medium engine speeds, likely due to faster ignition and elevated combustion temperatures. Unregulated species such as HCHO and N₂O decreased or remained negligible with increasing renewable content, while PNC and count mean diameter (CMD) were significantly reduced, confirming cleaner combustion and reduced soot formation. Overall, both HVO and HVOB20 demonstrated improved combustion efficiency and emission performance while ensuring full engine operability without calibration adjustments. These findings confirm the technical viability of renewable diesel fuels as immediate, drop-in solutions for reducing GHG emissions.
Zaccai, Martina, Chiavola, Ornella, Palmieri, Fulvio, Verdoliva, Francesco
Research on Electro-Hydraulic Compound Braking Coordinated Control Strategy Based on Sliding Mode Control2026-01-06314/7/2026
Hydraulic braking torque and motor braking torque are the main sources of braking torque of new energy vehicles. Hydraulic braking converts vehicle kinetic energy into heat dissipation, and motor braking converts vehicle kinetic energy into electric energy to achieve energy recovery. In the process of vehicle braking, when the wheels tend to lock, it is easy to cause vehicle instability, which seriously threatens the safety of driving. Therefore, how to coordinate the braking torque of the two braking systems to ensure the vehicle braking safety and energy recovery efficiency is still an urgent problem to be solved. In this paper, the electric vehicle equipped with electro-hydraulic compound braking system is taken as the research object, and the electro-hydraulic compound braking coordinated control strategy considering the general braking state and emergency braking state is proposed. Firstly, a 3-DOF vehicle longitudinal dynamic model is established according to the vehicle dynamic characteristics. Secondly, in the general braking state, the braking torque of the front and rear axles is optimally distributed with the energy recovery as the optimization objective. Then, in the emergency braking state, taking the vehicle braking safety as the optimization target, based on the sliding mode control method, by adjusting the braking torque of the front and rear axles to make the actual slip ratio follow the expected slip ratio, the optimal control of the vehicle slip ratio is carried out. Finally, the electro-hydraulic compound braking torque distribution is carried out on the braking torque of the rear axle. Simulation and real vehicle test results show that, compared with the conventional rule-based coordinated control strategy, the proposed strategy significantly reduces the fluctuation of vehicle slip ratio and improves the energy recovery efficiency by at least 7.7%, so the vehicle safety and energy recovery efficiency are significantly improved.
Zhao, Binggen, Zhao, Bingquan, Zhang, Xiaoyang, Wang, Zhenfeng, Zhao, Gaoming, He, Chengkun, Zhang, Junzhi, Ma, Changye
Theoretical Analysis and Forecasting of Gust Resistance in Rail Crane2025-99-022612/23/2025
Rail cranes are often subjected to sudden gusts of wind during the course of their work. In the event that a crane lacks adequate windproof capabilities, its movement along the track may have a significant impact on its own functionality and the safety of the surrounding equipment. Consequently, the prediction of the capacity of the rail crane to impede sudden gusts of wind, and the rational configuration of its windproof apparatus, is paramount to the crane’s ability to withstand wind. This paper conducts a systematic theoretical analysis of the gust resistance of rail crane with different windproof device configurations. It considers the movement of the wheels under wind influence and the windproof characteristics of other devices along the track direction. A theoretical formula is established to predict the gust resistance of rail crane, enabling the estimation of their maximum windproof capacity and providing a foundation for the selection and configuration of windproof devices. The calculation results demonstrate that the maximum wind capacity of the rail crane and crane parameters, wheel braking device braking torque and windproof device performance, cannot simply be considered as the maximum resistance of various types of windproof device sum. The results of the study provide a selection basis for the choice of wheel braking torque and the combination configuration of wind protection devices in the design of crane wind protection.
Zhang, Guo, Wang, Gongxian, Hu, Zhihui, Sun, Hui
Multi-Physics Numerical Modelling of a Magnetorheological Braking System2025-36-005012/18/2025
The global effort to reconsider transport in compliance with ecological challenges leads to a significant increase in the market share of Electric Vehicles (EVs), enlightening secondary sources of pollution. One of the most important is the particles emitted by the abrasion of braking pads. The innovative system addressed in this paper is among the most promising non-polluting solutions to ensure safety and comfort. It uses the capability of the Magneto-Rheological Fluid (MRF) to change its properties when subjected to a magnetic field, generating a braking torque between a stator and a rotor. This study focuses on characterizing the system's performance and endurance during an emergency braking situation by developing a numerical model that involves fluid and structural considerations. This model takes the form of a Finite-Element Model (FEM) that interpolates local forces determined from Computational Fluid Dynamics (CFD) and takes them as input. It enables analysis of the stresses induced by the variation of fluid behavior described by a Bingham theoretical model developed following experimental rheological results.
de Carvalho Pinheiro, Henrique, Billiant, Lucas, Imberti1, Giovanni, Carello, Massimiliana
Identification of Runway Friction Coefficient Using Extended Kalman Filter09-13-02-001212/11/2025
Aircraft operations during landing or takeoff depend strongly on runway surface conditions. Safe runway operations depend on the tire-to-runway frictional force and the drag offered by the aircraft. In the present research article, a methodology is developed to estimate the braking friction coefficient for varied runway conditions accurately in real-time. To this end, the extended Kalman filtering technique (EKF) is applied to sensor-measured data using the on-ground mathematical model of aircraft and wheel dynamics. The aircraft velocity and wheel angular velocity are formulated as system states, and the friction coefficient is estimated as an augmented state. The relation between the friction coefficient and wheel slip ratio is established using both simulated and actual ground roll data. Also, the technique is evaluated with the simulated data as well as real aircraft taxi data. The accuracy of friction estimation, with and without the measurement of normal reaction force on the landing gear, is analyzed using the simulated data. The friction coefficient vs slip ratio curve, derived from the empirical “Magic formula”, compares well with the estimated maximum tire-to-ground braking friction, and a shift in optimal slip is observed in actuality compared to the predictions. The brake disc friction coefficient is also estimated during the process since the brake torque measurements are not available in the actual data. The estimated friction coefficient, which represents the real characteristics of the runway, can be used to tune the control algorithms of the aircraft’s anti-skid brake management system for various runway conditions. While improvements in anti-skid efficiency alone may not directly prevent all runway excursions, accurate real-time friction estimation enhances the predictability and reliability of braking action, supporting safer operations under degraded or uncertain runway conditions. Moreover, the real-time estimation of tire-to-ground friction coefficient vs slip ratio curves can be used to develop adaptive control algorithms for the brake management system.
T.K., Khadeeja Nusrath, Singh, Jatinder
Characterization of the Brake Linings Coefficient of Friction by Means of Instrumented Suspensions Equipped on a Hybrid Race Vehicle10-10-01-000411/8/2025
The knowledge of the brake linings coefficient of friction (BLCF) is crucial for the control of the braking moment in modern vehicles equipped with electric powertrains. In the case of race vehicles equipped with carbon–carbon brakes, the coefficient of friction exhibits great variations as a function of the main influencing factors, namely the pressure, the temperature, and the sliding speed at the pad–disc interface. In this work, a Le Mans Hypercar instrumented with more than 150 sensors was adopted to perform the characterization of the BLCF from racetrack acquisitions. The front and rear left suspensions of the vehicle were instrumented with strain gauge channels and position transducers to acquire the reaction loads at the upright and the orientation of the arms. Then, the geometric matrix method was implemented for calculating the moments at the upright from which the braking torque was derived without the need to know any of the wheel inertia, nor the driveshaft torque. Data from multiple acquisitions across different racetracks, operating temperatures, and ambient conditions were used to characterize the BLCF of the front and rear carbon brakes equipped on the vehicle. After implementing pre-processing steps aimed at improving data homogeneity, two friction maps were characterized for the front and rear systems, respectively. The friction maps were validated against new experimental data showing an average 3% error reduction over assuming a constant BLCF. Accordingly, the characterized friction maps can be integrated in the brake-by-wire system of the vehicle for accurate caliper pressure control through real-time estimation of the BLCF from commonly available sensor signals, such as caliper pressure, wheel speed, and disc temperature. In this context, the effectiveness of the friction maps was demonstrated by comparing the predicted brake moments with the torques measured by the instrumented suspensions, highlighting the advantages over assuming a constant BLCF.
Cortivo, Davide, Vendramin, Mattia, Dindo, Luigi
Simulation of Hydraulic Retarder Using Particleworks2025-28-038210/30/2025
This study explores the application of Particleworks, a meshless CFD solver based on the Moving Particle Simulation (MPS) method, for simulating hydraulic retarders. Two distinct models were used: one for validating physical fidelity and another for conducting performance-focused design investigations. Validation results demonstrated that Particleworks closely aligns with experimental data from the reference literature, effectively capturing torque variations with rotor speed effect. A sensitivity study also emphasized the importance of particle resolution on accuracy and computational cost. Design studies using an in-house hydraulic retarder model assessed the influence of flow rate, rotor speed, working fluid, temperature, and cup geometry on braking torque. Notably, torque increased with rotor speed and steeper cup angles, while thermal effects and fluid properties significantly impacted performance trends. Comparative analysis with Star-CCM+ showed that Particleworks offers similar predictive accuracy but with substantial gains in pre-processing, setup, and runtime efficiency. These findings establish Particleworks as a robust and practical alternative to conventional CFD for rapid, iterative retarder design and analysis.
Kumar, Kamal S., Chaudhari, Gunjan B.
Preliminary Multi-Physics Modelling and Characterization of a Magneto-Rheological Brake2025-01-03479/15/2025
Magneto-Rheological Fluid (MRF) is a smart material used in several applications for its ability to switch from fluid behaviour to solid-like conditions if a magnetic field is present. The dependency of viscosity on magnetic field makes this fluid suitable for braking system of electric vehicles, thanks to its high controllability and response time in the whole operative range. The main parameters that influence the behaviour of the fluid, and so the braking action of the system, are magnetic field and rotational velocity. In general, the variable physical properties make it complicated to simulate the system and its behaviour in different operating conditions. Therefore, it is usually necessary to build a physical prototype to experimentally verify the response of the braking system at different driving conditions. This paper presents the development of a virtual model of Magneto-Rheological Brakes (MRB) whose validity is extended to different driving conditions. This can be accomplished by creating two coupled model, an electro-magnetic and a fluid-dynamic, using respectively Ansys Electronics Desktop 2D Maxwell and Ansys Fluent. Both the models are validated by comparing the magnetic flux density and the braking torque obtained from the experimental test campaign of the braking system prototype at different coil currents. The simulation and experimental results present a good correlation and allow to evaluate a wide range of operative and driving conditions of the braking system. The validation allows to use the developed simulation methodology to design and to adapt the braking system to any other specific application.
De Luca, Elena, Imberti, Giovanni, de Carvalho Pinheiro, Henrique, Carello, Massimiliana
A Study on the Prediction Method of Durability Characteristics of Brake Judder Using Simulation2025-01-03469/15/2025
In order to predict the durability characteristics of the brake judder, it is determined by analyzing the brake DTV (Disc Thickness Variation) and BTV(Brake Torque Variation) through the durability evaluation of the brake system or the vehicle. However, this method requires the real products and takes a long time to derive the result. When judder problems occur due to durability, there are many difficulties in deriving improvement plans through test methods. Therefore, in this study, CAE was used to derive the initial wear amount of the disc, and a method of predicting DTV after durability was developed using the results.
Hwang, Jaekeun, Kim, Sungho, Kim, Jeongkyu, Kang, Donghoon
Development of a Robust Framework for Fault Detection and Quantification in Automotive Drum Brakes Using Vibration Measurements and ANN10-09-03-00244/15/2025
Passenger safety is of utmost importance in the automotive industry. Hence, the health of the components, especially the brake system, should be effectively monitored. On account of the significance of artificial intelligence in recent times, any brake fault resulting during operation can be accurately detected using a combination of advanced measurement techniques and machine learning algorithms. The current study focuses on developing and evaluating a robust framework to quantify and classify the faults of a general automotive drum brake. For this purpose, a new experiment for a drum brake, which can be operated under a controlled environment with known levels of faults, is developed. The experiment is instrumented to measure the fundamental dynamic signals (such as brake torque, the angular velocity of the brake drum, and brake shoe accelerations) during a braking event. The response signals from several experiments with various faults and operating conditions serve as the input dataset for establishing the fault quantification algorithm. Multiple variants of this algorithm are devised using different subsets of the input dataset. The selection of features in each variant is done through sensitivity-based segregation with the help of artificial neural networks. The performance of all the variants is comparatively evaluated, and the best among them is determined based on the fault quantification error. Finally, fault classification is carried out using the best variant after establishing the classification thresholds based on the confusion matrix. The following are the novel aspects of this work: (i) design and development of a laboratory experiment for drum brakes that can imitate a real-life braking condition; (ii) measurement of the dynamic response of the system during a typical braking event with a controlled type and level of brake fault using appropriate instrumentation; (iii) estimation of the magnitude of multiple brake faults, in addition to their classification; and (iv) identification of the critical vibration measurements necessary for detecting faults in brakes. In addition, the physical insights into the brake system response, selected features, and the fault quantification algorithm are presented. The proposed framework can also be implemented for fault diagnosis in different automotive subsystems by using an equivalent experiment. The goal of the current work is to develop a simple in situ tool for monitoring the health and diagnosing faults in automotive drum brakes. When integrated with other smart diagnostic and prognostic features, this tool can help automotive manufacturers improve passenger safety.
Yella, Akash, Bharinikala, Yuva Venkat Ajay, Sundar, Sriram
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 Zero-Emissions Braking System: Experimental Setup, System Characterization and Model Validation2025-01-82504/1/2025
Following the current need of the automotive sector on reducing secondary emissions coming from non-exhaust sources, this paper presents an innovative zero-emissions magneto-rheological braking system, specifically designed to reach future brake emission targets while maintaining safety brake performance. In particular, the article focusses on the experimental setup design to evaluate a full-sized brake prototype under real load conditions and it presents the first experimental results. The zero-emission braking prototype has been developed for reaching performance compatible with the automotive application, specifically a segment-A vehicle, being able to generate enough braking torque as to perform an emergency brake maneuver without any other traditional braking system. A central aspect to confirm the system’s performance is the development of a test bench engineered for assessing the magneto-rheological braking technology. Detailed insights into the comprehensive strategy underpinning the design of the test bench are provided, emphasizing its ability to faithfully replicate diverse driving scenarios and evaluate multiple braking performances. After an initial virtual validation, the first brake prototype, featuring an electric in-wheel motor with an integrated innovative braking system, was experimentally tested on a dedicated bench to verify peak torque performance and system reliability. The paper thus presents the results obtained by the first experimental tests, considering the maximum braking capability of the system, its behavior under multiple rolling conditions and under different braking commands applied, to develop a braking solution able to maintain similar braking performance as traditional disk-brakes, but, at the same time, respecting the stringent environmental braking regulations, and promoting sustainable and efficient solutions aligned with environmental goals.
Tempone, Giuseppe Pio, De Carlo, Matteo, Carello, Massimiliana, de Carvalho Pinheiro, Henrique, Imberti, Giovanni
Study on Emergency Obstacle Avoidance Lateral Stability Control of Tractor Semitrailer Vehicles2025-01-82964/1/2025
As a crucial component of highway freight systems, tractor semitrailer vehicles play a key role in the transportation industry. However, their complex vehicle structure can lead to significant lateral instability during emergency obstacle avoidance, posing challenges to the vehicle's dynamic stability and safety. To enhance the emergency obstacle avoidance lateral stability of tractor semitrailer vehicles, a direct yaw moment lateral stability control strategy based on differential driving/braking is proposed. First, a 3-degree-of-freedom ideal linear dynamic model of the tractor-semitrailer is established, and its accuracy is validated. Then, a lateral stability control strategy for emergency obstacle avoidance is proposed. The upper-layer controller employs an improved feedforward differential model-free adaptive control (IMFAC) method to track the target yaw rate and vehicle sideslip angle, while the lower-layer controller focuses on optimizing tire load rate. Additionally, a drive/brake torque distributor is introduced to prioritize regenerative braking. The proposed control strategy is validated under simulated DLC conditions representing emergency obstacle avoidance. The results show that the designed controller improves the lateral stability of the tractor-semitrailer by over 30% in DLC scenarios, ensuring accurate trajectory tracking while maintaining low drive wheel tire load rate. This effectively extends the safety margin for tractor-semitrailer obstacle avoidance and provides valuable insights for improving lateral stability during emergency maneuvers.
Guo, Shaozhong, Dou, Jingyang
Vehicle Motion Management - A Model Predictive Control Approach to Realize Holistic Redundancy to Enable Actuator Fail Operational Autonomous Driving2025-01-88124/1/2025
Since the introduction of ABS (1978), TCS (1986) and ESC (1995) in series production, the number of modern vehicle dynamics control functions and advanced driver assistance systems (ADAS) has been continuously increasing. Meanwhile, many functions are available that influence vehicle motion (vehicle dynamics). Since these are only partially and not hierarchically coordinated, the control of vehicle motion is still suboptimal. Current megatrends (automated driving, electromobility, software-defined vehicles) and new key technologies (steer-by-wire, brake-by-wire, domain-based E/E architectures) lead to an increasing number of electrified, motion-relevant components being introduced into series production. These components enable the development of an integrated chassis control (ICC) that controls all motion-relevant components, networks them with each other and coordinates them holistically to optimally control the vehicle motion regarding an adjustable desired driving behavior. Vehicle Motion Management (VMM), which is being developed by IAV GmbH as ICC, uses model predictive control (MPC) to realize individually adjustable driving behavior. This not only combines and weights classic target criteria of driving safety (stability, controllability) and driving comfort with new target criteria of automated driving functions (energy efficiency, chassis emissions) but also enables fault-tolerant vehicle motion. This paper investigates in simulation whether the VMM is able to realize the lateral control of automated driving functions in the event of a failure of the steer-by-wire system by other motion-relevant components and maintaining the vehicle’s cornering. This paper compares three different powertrain topologies to find out which motion-relevant components are necessary to maintain cornering. The driving situation consists of stationary straight ahead driving and then cornering. When entering the corner, the steering system is not able to set a wheel steering angle due to a sudden failure. The VMM must control other motion-relevant components to maintain cornering. The path parameters (curve radius, clothoid parameter) are defined by the minimum parameters of the standardized long-distance German highway to map the corner case. This corner case is run for two different, statistically relevant driving speeds and three different powertrain topologies (with different motion-relevant components). To evaluate whether the vehicle maintains the lane, the maximum lateral deviation during cornering was calculated. The results show that cornering can be maintained at all driving speeds. The results also show that trajectory control is improved by adding further motion-relevant components.
Wielitzka, Mark, Ahrenhold, Tim, Vocht, Moritz, Rawitzer, Jonas, Schrader, Jonas
Research on Composite Braking Strategy of Pure Electric Commercial Vehicle on Downhill Low-Adhesion Road Considering Rainfall Intensity2025-01-88134/1/2025
As a distributed wire control brake system, the electro-mechanical brake (EMB) may face challenges due to the need to integrate the actuator in the limited space beside the wheel. During extended downhill braking, especially on wet roads with reduced adhesion, the EMB must operate at high intensity. The significant heat generated by friction can lead to thermal deformation of components, such as the lead screw, compromising braking stability. This paper focuses on pure electric light trucks and proposes a tandem composite braking method. This approach uses an eddy current retarder (ECR) or motor to provide basic braking torque, while the EMB supplies the dynamic portion of the braking torque, thereby alleviating the braking pressure on the EMB. First, a driver model, tire model, motor model, and braking models are developed based on the vehicle's longitudinal dynamics. In addition, the impact of various factors, such as rainfall intensity, road slope, ramp length and vehicle speed, on the road adhesion coefficient is analyzed. Combined with road conditions and driver intentions, three state variables—vehicle speed, battery state of charge, and braking intensity — are employed as control inputs. A fuzzy controller is then designed to distribute the basic braking torque between the motor and retarder. Additionally, a slip ratio controller is developed to dynamically adjust the braking torque of the electro-mechanical brake, preventing wheel lock-up. Finally, simulations are conducted using MATLAB/Simulink to validate the effectiveness of the proposed composite braking method.
Liu, Wang, Zhang, Yu, Xiao, Hongbiao, Shen, Leiming
Model-Based Vehicle Mass Estimation for Enhanced Adaptive Cruise Control Performance02-18-02-00092/19/2025
This study presents the development and integration of a vehicle mass estimator into the ZF’s Adaptive Cruise Control (ACC) system. The aim is to improve the accuracy of the ACC system’s torque control for achieving desired speed and acceleration. Accurate mass estimation is critical for optimal control performance, particularly in commercial vehicles with variable loads. The incorporation of such mass estimation algorithm into the ACC system leads to significant reductions in the error between requested and measured acceleration during both flat and uphill driving conditions, with or without a preceding vehicle. The article details the estimator’s development, integration, and validation through comprehensive experimental testing. An electric front-wheel drive van was used. The vehicle’s longitudinal dynamics were modeled using D’Alembert’s principle to develop the mass estimation algorithm. This algorithm updates the mass estimate based on specific conditions: zero brake torque, high longitudinal acceleration, minimal slope, adequate speed, minimal wheel slip, and low yaw rate. These conditions ensure accurate mass estimation by minimizing the effects of nonlinearities and external disturbances. Experimental results showed that the mass estimator converges to the actual mass value as more samples are collected. Tests with varying loads confirmed the estimator’s accuracy, achieving a maximum absolute error of 72 kg and a percentage error of 1.71 %. When integrated into the ACC system, the estimated mass improved the control accuracy, especially in acceleration phases, reducing the time to reach the desired speed. Both cruise control and follow control tests, performed on flat and uphill roads, demonstrated that the ACC system with the mass estimator achieved the desired acceleration more accurately than without it. This improved the overall responsiveness and comfort of the ACC system under different driving conditions. The findings highlight the importance of accurate mass estimation for enhancing adaptive vehicle control technologies, representing a significant advancement in ACC systems.
Marotta, Raffaele, D’Itri, Valerio, Irilli, Alessandro, Peccolo, Marco
Objectively Quantify Creep Groan and Dynamic Grunt Performance of Different Brake Friction Materials2024-01-30359/8/2024
The assessment of brake friction materials extends beyond squeal noise and thermal roughness testing as it play crucial role in other brake noise phenomena such as creep groan and dynamic grunt. These low frequency noise types are significant as they directly affect passengers comfort levels. Creep groan noise defined as audible stick-slip noise at low vehicle speed during partial brake application, typically encountered in dense traffic conditions. Dynamic grunt is another form of stick-slip noise observed during high-speed braking and it is noticeable just prior to vehicle’s complete stop. This noise is indicative of frictional interaction between the brake pad and disc under deceleration scenario. Comparative analysis of two distinct brake friction materials was conducted utilizing both NVH dynamometer and real-world vehicle testing. The NVH dynamometer procedure was designed to evaluate the creep groan and dynamic grunt phenomena under controlled environmental conditions. For the creep groan assessment, a static motor varied speed between 0 and 2 kph under a constant brake pressure, whereas the dynamic grunt evaluation involved applying various braking speeds at different deceleration rates. Vehicle testing for dynamic grunt evaluated under varied temperature and humidity conditions, with the procedure repeated after 10,260 and 510 burnish stops to gauge materials performance consistency over time. Objective quantification of the dynamometer test data was achieved by analyzing peak-to-peak vibration amplitudes from accelerometer channel, vibration duration, brake torque variation, spectral density within the 0 to 1000 Hz range. In contrast, the vehicle tests relied on subjective evaluations from the drivers to gauge noise characteristics. The test results demonstrated the significant impact of the friction materials on both the dynamometer and vehicle testing outcomes. Material A exhibited superior performance, evidenced by notably lower peak-to-peak vibration amplitudes and spectral density values compared to Material B, implying the importance of material selection in mitigating undesirable brake noise phenomena.
Barot, Ankit, Wang, Weicherng
Brake Heat Capacity Prediction Using a Machine-Learned Friction Coefficient Model and Virtual Wheel Brake2024-01-30549/8/2024
Recently, the increasing complexity of systems and diverse customer demands have necessitated the development of highly efficient vehicles. The ability to accurately predict vehicle performance through simulation allows for the determination of design specifications before the construction of test vehicles, leading to reduced development schedules and costs. Therefore, detailed brake thermal performance predictions are required both for the front and rear brakes. Moreover, scenarios requiring validation, such as alpine conditions that apply braking severity to xEV with the regenerative braking system, have become increasingly diverse. To address this challenge, this study proposes a co-simulation method that incorporates a machine-learned brake pad friction coefficient prediction model to enhance the accuracy of brake thermal capacity predictions within the vehicle simulation environment. This innovative method allows for the simultaneous prediction of both front and rear-wheel brakes. The required brake torques for the front and rear wheels are calculated based on the vehicle model and driving scenarios. The brake system model generates the necessary pressure during deceleration, whereas the friction coefficient is crucial in creating brake torque, resulting in brake power for both the front and rear brakes. Within the simulation model, the virtual wheel brake calculates the speed, pressure, and disc temperature based on vehicle driving schedules. The machine-learned model utilizes these variables as inputs and returns the friction coefficient. The prediction accuracy of torque and disc temperature improved significantly as the virtual wheel brake utilized the friction coefficient received from the model trained using the mixed-effects random forest algorithm.
Cho, Sunghyun, Baek, SangHeum, Kim, Min Soo, Hong, Incheol, Kim, Hyun Ki, Kim, Gwichul, Lee, Jounghee
CFD Methodology Development to Predict Lubrication Effectiveness in Electromechanical Actuators2024-26-04666/1/2024
Electromechanical actuators (EMAs) play a crucial role in aircraft electrification, offering advantages in terms of aircraft-level weight, rigging and reliability compared to hydraulic actuators. For various functions within the actuator such as prevention of backdriving, torque limiting, damping, braking, etc., skewed roller devices are typically employed to provide braking torque. These technology components are continuing to be improved with analysis driven design innovations e.g., U.S. Pat. No. 8,393,568. The device has the rollers skewed around their own transverse axis that allow for a combination of rolling and sliding against the stator surfaces. This friction provides the necessary braking torque. By controlling the friction radius and analyzing the Hertzian contact stresses, the device can be sized for the desired duty cycle. While operating, the rollers require sufficient lubrication to ensure local temperatures do not exceed limits of the components or the lubricant itself. This was analyzed by multiphase computational fluid dynamics (CFD) modeling to predict fluid characteristics around the skewed rollers and conjugate heat transfer modeling to identify component overheating. Elasto-Hydrodynamic lubrication (EHL) theory was used to estimate the lubrication thickness around the rollers. The analysis revealed the formation of vapor due to the high rotational speed of the rollers with respect to the stator discs, resulting in direct metal-to-metal contact. Consequent testing of the device in a Tribological Testing Machine confirmed the findings with wear patterns on the stator consistent with loss of lubrication. In addition, the temperature data aligned within 2°C of predicted CFD results at key locations on the device. Given the high fidelity of the analysis methodology, future steps include assessing new design iterations against intended performance parameters.
Bhardwaj, Divyanshu, Kumar, Anant, George, Jubin
Innovative Zero-Emissions Braking System: Performance Analysis Through a Transient Braking Model2024-01-25534/9/2024
This paper presents the analysis of an innovative braking system as an alternative and environmentally friendly solution to traditional automotive friction brakes. The idea arose from the need to eliminate emissions from the braking system of an electric vehicle: traditional brakes, in fact, produce dust emissions due to the wear of the pads. The innovative solution, called Zero-Emissions Driving System (ZEDS), is a system composed of an electric motor (in-wheel motor) and an innovative brake. The latter has a geometry such that it houses MagnetoRheological Fluid (MRF) inside it, which can change its viscous properties according to the magnetic field passing through it. It is thus an electro-actuated brake, capable of generating a magnetic field passing through the fluid and developing braking torque. A performance analysis obtained by a simulation model built on Matlab Simulink is proposed. The model is able to simulate the transient 1D motion of an electric vehicle equipped with four wheels, each having a ZEDS mounted. It has the ability to simulate a road test, supervise the behavior of the vehicle, monitoring parameters such as the State of charge (SoC) of the battery, the current used by the vehicle's battery, speed, drive torque and the decoupling between the regenerative braking torque and the Magneto-Rheological brakes torque. The primary goal of the model is to verify the capability of the braking system to develop a sufficiently high torque to satisfy safety standards and regulation requests. The study creates also a starting point for thermal analysis of the system.
Tempone, Giuseppe Pio, Imberti, Giovanni, de Carvalho Pinheiro, Henrique, Carello, Massimiliana
Torque Vectoring for Lane-Changing Control during Steering Failures in Autonomous Commercial Vehicles2024-01-23284/9/2024
Lane changing is an essential action in commercial vehicles to prevent collisions. However, steering system malfunctions significantly escalate the risk of head-on collisions. With the advancement of intelligent chassis control technologies, some autonomous commercial vehicles are now equipped with a four-wheel independent braking system. This article develops a lane-changing control strategy during steering failures using torque vectoring through brake allocation. The boundaries of lane-changing capabilities under different speeds via brake allocation are also investigated, offering valuable insights for driving safety during emergency evasions when the steering system fails. Firstly, a dual-track vehicle dynamics model is established, considering the non-linearity of the tires. A quintic polynomial approach is employed for lane-changing trajectory planning. Secondly, a hierarchical controller is designed. The upper layer employs a three-stage cascaded proportional integral controller to determine the total yaw moment required for lane changing, considering the influence of lateral tire forces on brake allocation. The middle layer uses constraint optimization to manage braking force distribution among the four wheels. The lower layer's actuator generates brake torque through brake cylinder pressurization. Finally, the effectiveness and feasibility of the control strategy are validated using joint simulations on Matlab/Simulink and Trucksim over diverse longitudinal distances. Simulation results indicate that autonomous commercial vehicles can execute swift and safe lane changes at varying speeds during steering failures.
Lu, Ao, Li, Runfeng, Yinggang, Xu, Nie, Zexin, Li, Peilin, Tian, Guangyu
A Suspension Tuning Parameter Study for Brake Pulsation2024-01-23194/9/2024
Brake pulsation is a low frequency vibration phenomenon in brake judder. In this study, a simulation approach has been developed to understand the physics behind brake pulsation employing a full vehicle dynamics CAE model. The full vehicle dynamic model was further studied to understand the impact of suspension tuning variation to brake pulsation performance. Brake torque variation (BTV) due to brake thickness variation from uneven rotor wear was represented mathematically in a sinusoidal form. The wheel assembly vibration from the brake torque variation is transmitted to driver interface points such as the seat track and the steering wheel. The steering wheel lateral acceleration at the 12 o’clock position, driver seat acceleration, and spindle fore-aft acceleration were reviewed to explore the physics of brake pulsation. It was found that the phase angle between the left and right brake torque generated a huge variation in brake pulsation performance. Multiple analyses have been run to understand the relationship between the brake pulsation performance and suspension tuning. The suspension tuning parameters incorporated in the study were suspension bushing stiffness, bushing damping for a potential hydro-bushing implementation, the magnitude of the pulsation torque, unsprung mass, and spindle length. Simulation results have demonstrated the physics behind the brake pulsation reasonably well. This study would enable engineers to find a good compromise of suspension tuning to improve brake pulsation in vehicle dynamics performance.
Hong, Hyung-Joo, Lee, Changwook, Jun, Hyochan, Zhu, Dongzhe
Experimental Comparison of Spark and Jet Ignition Engine Operation with Ammonia/Hydrogen Co-Fuelling2024-01-20994/9/2024
Ammonia (NH3) is emerging as a potential fuel for longer range decarbonised heavy transport, predominantly due to favourable characteristics as an effective hydrogen carrier. This is despite generally unfavourable combustion and toxicity attributes, restricting end use to applications where robust health and safety protocols can always be upheld. In the currently reported work, a spark ignited thermodynamic single cylinder research engine was upgraded to include gaseous ammonia and hydrogen port injection fueling, with the aim of understanding maximum viable ammonia substitution ratios across the speed-load operating map. The work was conducted under stoichiometric conditions with the spark timing re-optimised for maximum brake torque at all stable logged sites. The experiments included industry standard measurements of combustion, performance and engine-out emissions. It was found possible to run the engine on pure ammonia at low engine speeds at low to moderate engine loads in a fully warmed up state. When progressively dropping down below this threshold load limit, an increasing amount of hydrogen co-fueling was required to avoid unstable combustion. All metrics of combustion, efficiency and emissions tend to improve when moving upwards from the threshold load line. A maximum net indicated efficiency of 40% was achieved at 1800rpm 16bar IMEPn, with efficiency tending to increase with speed and load. Furthermore, comparing spark ignition with active and passive jet ignition (with the former involving direct injection of hydrogen into the pre-chamber only and the main chamber port fueled with ammonia), at different loads it was found that active systems can significantly improve early burn phase and reduce engine-out NOx compared to passive jet ignition and SI. While both Jet ignition systems required supplementary hydrogen, it accounted for ~1% (active) of the total fuel energy at high loads increasing with reduction in engine load.
Ambalakatte, Ajith, Cairns, Alasdair, Geng, Sikai, Varaei, Amirata, Hegab, Abdelrahman, Harrington, Anthony, Hall, Jonathan, Bassett, Michael
Design, Modeling and Analysis of Customized Brake Caliper for SAE BAJA Vehicle2023-01-51062/23/2024
All-terrain vehicles are gaining more popularity due to their off-roading nature. In this ATV one of the most important components which gives us a safe ride and control is the braking system. This study presents a detailed view of the design, modelling and analysis of brake caliper using Solidworks 2022 and Altair Hyperworks software for an all-terrain vehicle. A single piston floating caliper which is designed to fulfil conditions such as compact size to fit into wheel assembly, to provide adequate strength and great efficiency of about 80% during off-road conditions. This caliper is mainly designed to withstand a braking torque of 315645 Nm. The main aim of designing the caliper is to fit inside the wheel assembly of the ATV so that the interaction between the caliper is not with any other components. Furthermore, considerations are accounted as machinability are integrated into the design process, ensuring that the proposed brake caliper systems are performing well.
Ravi Kumar, L., Prathiesh Lalan, R. A., Shriram Naibal, B., Chiranjeev Sanjay, P., Gananathji Naveen Kishore, S., Vasundharadevi, D.
Calibration of an Inertial Measurement Unit and Its Impact on Antilock Braking System Performance2024-26-00141/16/2024
An Inertial Measurement Unit (IMU) provides vehicle acceleration that can be used in Active Vehicle Safety Systems (AVSSs). However, the signal output from an IMU is affected by changes in its position in the vehicle and alignment, which may lead to degradation in AVSS performance. Investigators have employed physics and data-based models for countering the impact of sensor misalignment, and the effects of gravity on acceleration measurements. While physics-based methods utilize parameters varying dynamically with vehicle motion, data-based methods require an extensive number of parameters making them computationally expensive. These factors make the above-explored methods practically challenging to implement on production vehicles. This study considers a 6-axis IMU and evaluates its impact on Antilock Braking System (ABS) performance by considering the IMU signal obtained with different mounting orientations, and positions on a Heavy Commercial Road Vehicle (HCRV). It then develops a computationally effective transformation that requires only two parameters for compensating the IMU sensor mis-orientation and extracting vehicle acceleration from the IMU signal. This transformation also provides physical intuition on the sensor mis-orientation for gauging the vehicle’s dynamic characteristics. Subsequently, a Kalman filter is utilized to estimate the unresolved offset in longitudinal acceleration. The IMU calibration combined with an ABS algorithm was evaluated in a Hardware-in-Loop experimental setup using IPG TruckMaker®. Improvements in longitudinal acceleration estimates by 94-98% were achieved with the calibration algorithm, when compared to the unprocessed IMU data. Moreover, the processed longitudinal acceleration estimates significantly enhanced wheel slip estimation performance by over 60% for a majority of the test cases, avoiding critical problems of wheel lock, and zero brake torque before the vehicle reaches its crawling speed. The outcomes of this study are expected to contribute as a critical block in the development of an indigenous ABS solution for HCRVs.
Dixit, Chitrartha, Gaurkar, Pavel, Ramakrishnan, Rajesh, Shankar Ram, C S, Vivekanandan, Gunasekaran, Sivaram, Sriram
Fault Compensation Control for Regenerative Braking of Distributed Drive Electric Vehicle Based on Hierarchical Control2023-01-706112/20/2023
For distributed drive electric vehicles (DDEV) equipped with an electronic hydraulic braking system (EHB) and four-wheel hub motors, when one or more hub motors have regenerative braking failure, because the braking torque of the four wheels is inconsistent, additional yaw moment will be formed on the vehicle, resulting in the loss of directional stability of the vehicle during braking. If it occurs at high speeds, it will further threaten driving safety. To solve the above problems, a new hierarchical control architecture is established in this paper. Firstly, taking DDEV as the research object, the vehicle dynamics model and EHB braking system model are built. Then, a state observer based on an adaptive Kalman filter is designed in the upper layer to estimate the vehicle’s sideslip angle and yaw rate in real time. In the judgment decision-making layer, the phase plane is used to divide the stability domain boundary of the vehicle, and the quasi-stability tolerance band judges the vehicle’s driving state. Secondly, the lower stability controller is constructed based on the sliding mode control theory. EHB can flexibly distribute hydraulic braking force to compensate for the vehicle’s braking force, offset the additional yaw moment, and maintain the straight line of the vehicle. Finally, experimental verification is carried out in Matlab/ CarSim and hardware-in-the-loop (HIL) platforms. The results show that the proposed method can effectively predict the state and closed-loop stability control of DDEV, and reduce the deviation distance caused by regenerative braking failure, effectively ensuring the vehicle in the event of regenerative braking failure driving safety.
Fang, Ting, Zhao, Linfeng, Hu, Jinfang, Mei, Zhen, Wang, Muyun, Sun, Bin
Revolutionizing Electric Mobility: The Latest Breakthroughs in Tyre Design2023-28-005611/10/2023
The increasing demand for electric mobility has brought about significant advancements in tyre design. This paper covers the latest developments in tyre design that cater specifically to the needs of electric vehicles (EVs). EVs have unique performance characteristics that place greater emphasis on tyre requirements like High traction, Wear resistance, Low Cavity & pattern noise, Low Rolling resistance and High load carrying capacity. Hence, the tyre manufacturers have been working relentlessly to create advanced designs that can meet these requirements. This paper will cover various aspects of tyre design, including tyre cavity, tread patterns, sidewall design, compound & reinforcement design, and various construction techniques. The tyre cavity and tread pattern play a crucial role in the overall performance of an EV. The new tyre cavity with flat tread and adaptive tread pattern are optimized to provide low rolling resistance, pattern noise reduction and enhanced dry and wet traction. Additionally, the use of advanced materials such as high-performance functionalized polymers and high tenacity reinforcements has led to the creation of low rolling resistance, lightweight and durable tyres that can withstand high power, acceleration, and braking torque on driving wheels of EVs. Furthermore, the construction techniques of EV tyres have also seen significant improvements for durability to handle heavy battery packs. In addition, this paper also highlights various enabling technology like the use of foam technology for cavity noise reduction and Sealant technology for Extended mobility. In conclusion, this paper showcases the recent advancements in tyre design for EVs. The advancements in tyre design have enabled tyre manufacturers to create bespoke designs that cater to the specific needs of each EV model. These developments are crucial in promoting the adoption of electric mobility and improving the overall driving experience for EV users.
Krishnakumar, Jeyakumar, Subbian, Jaiganesh, C S, Midhunkrishna
Applying Ferritic Nitrocarburizing (FNC) in Conjunction with Smart ONC® on GCI Brake Rotors: The New Generation of FNC Rotors to Meet the Euro 7 Standards2023-01-188811/5/2023
As the regulations aiming to limit air pollution become stricter, the battle against non-exhaust emissions known to be harmful to human health and the environment is attracting more focus and extending worldwide. EVs are equipped with a hybrid braking system combining regenerative and hydraulic braking to provide the same performance as traditional vehicles. Whenever the regenerative braking torque is insufficient to give the necessary deceleration rate, the hydraulic and electromechanical braking torque is applied. Thus, the recuperative braking of EVs reduces the need for brakes. As the brakes are not used as often, dust and rust will accumulate and impede their performance, so brake problems can arise from not using them enough. Due to the extra weight of EVs compared to ICEVs, more particulates are released through increased corrosion and friction on the braking system. Grey cast iron brake rotors rust quickly, and excessive corrosion causes heavy damage to the rotor’s surface, which wears down severely, leading to mass loss, irregular vibration, and pedal pulsation when braking. Therefore, one of the most economical measures to effectively reduce particulate emissions (PM) is the application of ferritic nitrocarburizing. However, this approach is still insufficient to reach the desired objectives or address the challenges electric vehicles present. The new generation of FNC rotors developed by Nitrex R&D is not limited to FNC; the focus has shifted towards using Smart ONC®. This exclusive and promising process provides rotors with superior corrosion resistance, allowing them to withstand salt spray exposure for up to 120 hours without any corrosion. This is a tremendous improvement over FNC-treated rotors, which only last for less than 20 hours in the same environment. This paper and presentation will follow up on our contribution from 2022 and present Nitrex’s latest findings and developments.
Nousir, Saadia, Winter, Karl-Michael
Brake Control Allocation Employing Vehicle Motion Feedback for Four-Wheel-Independent-Drive Vehicle2023-01-186611/5/2023
This paper uses the brake control allocation method for Electric Vehicles (EVs) based on system-level vehicle Reference Point (RP) motion feedback. The RP motion control is an alternative to the standard brake torque allocation methods and results in improved vehicle stability in both longitudinal and lateral directions without requiring additional measurements beyond what is available in EVs with ABS and ESP. The proposed control law simplifies the brake torque allocation algorithm, reduces overall development time and effort, and merges most of the braking systems into one. Additionally, the measured or estimated signals required are reduced compared to the standard approach. The system-level RP measurements and references are transformed into individual wheel coordinate systems, where tracking is ensured by actuating both friction torques and electric motor regenerative torques using a proposed brake torque blending mechanism. The whole control system is validated in simulations using the Simulink vehicle dynamic simulator and IPG Carmaker high-fidelity simulator, utilizing the CTU FEE EFORCE formula model. Finally, a brake HiL stand validation is presented.
Vošahlík, David, Veselý, Tomáš, Hanis, Tomas, Pekar, Jaroslav
TOC99-05-04-0TOC8/3/2023
TOC
Tobolski, Sue
A Mid-fidelity Model in the Loop Feasibility Study for Implementation of Regenerative Antilock Braking System in Electric Vehicles10-07-03-00227/29/2023
The tailpipe zero-emission legislation has pushed the automotive industry toward more electrification. Regenerative braking is the capability of electric machines to provide brake torque. So far, the regenerative braking feature is primarily considered due to its effect on energy efficiency. However, using individual e-machines for each wheel makes it possible to apply the antilock braking function due to the fast torque-tracking characteristics of permanent magnet synchronous motors (PMSM). Due to its considerable cost reduction, in this article, a feasibility study is carried out to investigate if the ABS function can be done purely through regenerative braking using a mid-fidelity model-based approach. An uni-tire model of the vehicle with a surface-mount PMSM (SPMSM) model is used to verify the idea. The proposed ABS control system has a hierarchical structure containing a high-level longitudinal slip controller and a low-level SPMSM torque controller. Given the uncertainties of the tire–road dynamics, a sliding mode control method is designed and employed as a high-level slip controller. Also, a PID vector control method is used to keep the SPMSM braking torque at the optimal value requested by the high-level controller. Moreover, in order to estimate the tire longitudinal slip and vehicle velocity, an extended Kalman filter (EKF) is developed that estimates both parameters at the same time. The results show that the proposed hierarchical control and estimators can keep the tire longitudinal slip at the optimal value and prevent the wheel from locking in a variety of road conditions.
Ghanami, Nastaran, Nikzadfar, Kamyar, Mohammadi Daniali, Hamid Reza
Inertia Calculation for Single-Ended Inertia-Dynamometer TestingJ2789_202304 (Current)4/12/2023
This procedure provides methods to determine the appropriate inertia values for all passenger cars and light trucks up to 4540 kg of GVWR. For the same vehicle application and axle (front or rear), different tests sections or brake applications may use different inertia values to reflect the duty-cycle and loading conditions indicated on the specific test.
Brake Dynamometer Standards Committee
Combined Path Following and Vehicle Stability Control using Model Predictive Control2023-01-06454/11/2023
This paper presents an innovative combined control using Model Predictive Control (MPC) to enhance the stability of automated vehicles. It integrates path tracking and vehicle stability control into a single controller to satisfy both objectives. The stability enhancement is achieved by computing two expected yaw rates based on the steering wheel angle and on lateral acceleration into the MPC model. The vehicle's stability is determined by comparing the two reference yaw rates to the actual one. Thus, the MPC controller prioritises path tracking or vehicle stability by actively varying the cost function weights depending on the vehicle states. Using two industrial standard manoeuvres, i.e. moose test and double lane change, we demonstrate a significant improvement in path tracking and vehicle stability of the proposed MPC over eight benchmark controllers in the high-fidelity simulation environment. The numerous benchmark controllers use different path tracking and stability control methods to assess each performance benefit. They are split into two groups: the first one uses differential braking in the control output, while the second group can only provide an equal brake torque for the wheels in the same axle. Furthermore, the controller's robustness is evaluated by changing various parameters, e.g. initial vehicle speed, mass and road friction coefficient. The proposed controller keeps the vehicle stable at higher speeds even with varying conditions.
Lenssen, Daan, Bertipaglia, Alberto, Santafe, Felipe, Shyrokau, Barys
Driveline Control Influence when ABS Active2023-01-06624/11/2023
The interaction between driveline control and anti-lock braking system (ABS) control in electric vehicles (EV) was investigated based on multi-body dynamics (MBD) model and control model co-simulation. Two primary driveline control algorithms, active damping control and wheel flare control, were integrated with ABS control in Simulink model and the influence on ABS control was studied. The event for high mu to low mu transition was simulated. When ABS control is active on low mu surface, the vehicle shows large wheel slip and long duration time before wheel speed returns to stable control. This performance could be improved with activating driveline control. Deceleration uniformity metric shows that active damping control has very small effect when ABS control becomes stable after passing through the high mu to low mu transition period. Driveline damping control can help to reduce vibration, but it is difficult to find satisfied tuning for wheel speed performance. Wheel flare control can help to reduce the large wheel slip more effectively than ABS control. With proper tuning in ABS control, it can achieve smooth transition between wheel flare control and ABS control. Variation study on different brake torque level and different mu surface shows the performance is robust.
Xing, Xing, Clark, Mark, Morris, Robert
Combined Physical and ANN-Based Engine Model of a Turbo-Charged DI Gasoline Engine with Variable Valve Timing2023-01-01944/11/2023
High-efficient simulations are mandatory to manage the ever-increasing complexity of automotive powertrain system and reduce development time and costs. Integrating AI methods into the development process provides an ideal solution thanks to massive increase in computational power. Based on an 1D physical engine model of a turbo-charged direct injection gasoline engine with variable valve timing (VVT), a high-performance hybrid simulation model has been developed for increasing computing performance. The newly developed model is made of a physics-based low-pressure part including intake and exhaust peripheries and a neural-network-based high-pressure part for combustion chamber calculations. For the training and validation of the combustion chamber neural networks, a data set with 10.5 million operating points was generated in a short time thanks to the parallelizable combustion chamber simulations in stand-alone mode. The data set covers wide variation ranges of boundary and operating conditions in the combustion chamber including variable valve timings. A special neural network structure was configurated, which consists of five interconnected gated recurrent unit (GRU) sub-networks for calculating mass fuel burned, pressure values, the peak pressure position, NO emissions as well as knock condition. To form a whole working cycle simulation within GT-SUITE, the neural networks were converted into a functional mock-up unit (FMU), which is connected with the physics-based low-pressure part through FKFS RapidCylinder®. A performance evaluation of the hybrid engine model shows that, the mean deviations of brake torque, MFB50 and NO emissions compared to the physics-based reference mode are respectively 0.529%, 0.048°CA and 32.67ppm over the whole engine characteristic map, indicating an equal calculation quality. While maintaining the calculation accuracy, the neural networks with FMU connections realize a combustion chamber calculation 5- to 10-fold faster than real-time and an acceleration of the whole engine calculation of up to 80% compared to the completely physics-based simulation.
Wei, Jingsi, Liu, Mingjia, Angerbauer, Michael, Yang, Qirui, Xu, Hanjun, Grill, Michael, Kulzer, André, Chen, Ceyuan
Effect of Standard Tuning Parameters on Mixture Homogeneity and Combustion Characteristics in a Hydrogen Direct Injection Engine2023-01-02844/11/2023
Dihydrogen, as a zero CO2 fuel, is a strong candidate for internal combustion engine to limit global warming. This study shows the impact of standard tuning parameters on mixture homogeneity and combustion characteristics. A 2.2L Diesel engine on which the head was reworked to allow side mounted direct injector and central mounted spark plug was selected. The discussed tests were made at low engine speed and partial load. A spark advance sweep at different air-fuel ratios (λ) was conducted. The exponential relation between λ and NOx emissions is highly marked and extremely low NOx emissions up to 1.7 g/kWh at minimum spark advance for maximum brake torque can be measured. A λ sweep was performed at different starts of injection (SOI). The results show that, depending on the engine speed, a later SOI might lead to lower NOx emissions. For a λ setpoint of 1.8, at 1500 rpm, late SOI leads to 30% higher NOx emissions where at 2500 rpm these emissions are 26% lower. This assessment is explained by the cycle-to-cycle variations. Finally, the second λ sweep, where the rail pressure (Prail) was varied, reveals that maximizing the Prail does not necessarily lower down NOx emissions. At 2500 rpm of engine speed, for richer mixtures than λ = 1.8, the higher Prail leads to higher NOx emissions. Having a lower Prail might lead to a slightly leaner mixture near the spark plug at spark timing. This effect extends the ignition delay thus lower the NOx emissions.
LOW-KAME, Jean, Oung, Richard, Meissonnier, Guillaume, Da Graca, Mathieu, Doradoux, Laurent, Foucher, Fabrice
Methodologic Assessment of Brake-by-Wire System Modelling with Regard to Accuracy, Model Complexity and Optimization Efforts2023-01-06664/11/2023
Brake-by-wire systems are an innovative and important component of modern high-performance and also electrified vehicles. Due to their decoupled architecture, they enable driver-independent vehicle dynamics control (e.g., brake torque blending) and easy integration of assistance functionalities (e.g. Emergency Brake Assist (EBA)). On the other hand, the development of these functions can cause high costs and development effort, and testing can be critical in case of improper gain tuning. Therefore, already in the concept phase, a large part of the testing is shifted to virtual environments and simulations that allow safe and reproducible experiments without damage. Therefore, suitable and reliable models are needed to represent reality as accurately as possible. This paper deals with the modelling of a purely electrohydraulic brake-by-wire system and a hybrid system with electrohydraulic brakes on the front axle and electromechanical brakes on the rear axle. For comparison, both an experimental approach based on a second-order transfer function and an analytical model are used. These approaches are then evaluated in terms of their accuracy and reliability using real measurements in different dynamic test setups. Finally, it is shown how accurate the approaches are and what advantages can be achieved by using the different methods for system modelling.
Heydrich, Marius, Kellner, Björn, Ivanov, Valentin
Compound Brake Control for Improved Ride Comfort for Dual-rotor In-wheel Motor Electric Vehicles2023-01-05264/11/2023
Aiming at the problem of braking shock caused by the inconsistent response time of the inner motor (IM), the outer motor (OM) and the hydraulic brake when the regenerative braking mode of dual-rotor in-wheel motor (DRIWM) is switched, this paper proposes a U-shaped transition coordinated control strategy for the DRIWM. Ensure that the total braking torque can be smoothly transitioned when any one or more of the hydraulic braking torque, the braking torque of the IM and the braking torque of the OM enter/exit braking. The dynamic model of electric vehicle (EV) with DRIWMs is established, the division of braking mode is based on the principle of optimal DRIWM system efficiency, and the U-shaped transition coordinated controller of DRIWM is designed. Finally, two cases of switching the IM single braking mode to hydraulic braking mode and OM and hydraulic coordinated braking mode switching to compound braking mode are taken as examples to verify. The results show that, compared with the braking mode switching process without transition coordinated control, the U-shaped transition coordinated control strategy of the DRIWM proposed in this paper can make the DRIWM complete switching within 0.25s on the basis of the optimal system efficiency, which reduces the impact to 2 m/s3 and ensures a smooth transition of the total braking torque when switching.
leng, Fei, He, Ren
Mathematical formulation and Analysis of Brake Judder2023-01-01484/11/2023
The Brake judder is a low-level vibration caused due to Disc Thickness Variation (DTV), Temperature, Brake Torque Variation (BTV), thermal degradation, hotspot etc. which is a major concern for the past decades in automobile manufacturers. To predict the judder performance, the modelling methods are proposed in terms of frequency and BTV respectively. In this study, a mathematical model is constructed by considering full brake assembly, tie rod, coupling rod, steering column, and steering wheel as a spring mass system for identifying judder frequency. Simulation is also performed to predict the occurrence of brake judder and those results are validated with theoretical results. Similarly, for calculating BTV a separate methodology is proposed in CAE and validated with experimental and theoretical results.
S, Gurumoorthy, Bhumireddy, Yugandhar, Bourgeau, Alyssa, Bhimchand, Naresh
Research on Regenerative Braking Control Strategy of Commercial Vehicles Considering Battery Power Status2023-01-05364/11/2023
Regenerative braking is an effective way to increase the cruising range of vehicles. In commercial vehicles with large vehicle mass, regenerative braking can be maintained in a high-power working state for a long time theoretically because of the large braking torque and long braking time. But in fact, it is often impossible to run at full power because of battery safety problems. In this paper, a control strategy is designed to maintain the maximum power operation of regenerative braking as much as possible. The maximum charging power of the battery is obtained through the battery model, and it is set as the battery limiting parameter. The regenerative braking torque and power are obtained by using the motor model. The eddy current retarder is used to absorb the excess power that the battery can't bear, and the braking torque of the eddy current retarder is calculated. Finally, mechanical braking is used to make up the insufficient braking torque. A set of algorithms is designed based on the brake pedal opening balance of three braking modes. On the premise of ensuring battery safety, try to increase the priority of regenerative braking and reduce the use of mechanical braking. MATLAB is used to simulate the long downhill process of commercial vehicles at the toe of constant slope. Compared with the traditional regenerative braking method, the mechanical braking temperature in this work decreased by 37.62% on average. This work reduces the mechanical braking pressure, reduces the risk of overheating of commercial vehicle brakes, and improves the and safety of the whole vehicle.
Xie, Beichen, Ding, Kangjie, Lin, Zhenmao
Performance, Combustion and Emissions Evaluation of Liquid Phase Port-Injected LPG on a Single Cylinder Heavy-Duty Spark Ignited Engine2023-01-02454/11/2023
Liquefied petroleum gas (LPG), like many other alternative fuels, has witnessed increased adoption in the last decade, and its use is projected to rise as stricter emissions regulations continue to be applied. However, much of its use is limited to dual fuel applications, gaseous phase injection, light-duty passenger vehicle applications, or scenarios that require conversion from gasoline engines. Therefore, to address these limitations and discover the most efficient means of harnessing its full potential, more research is required in the development of optimized fuel injection equipment for liquid port and direct injection, along with the implementation of advanced combustion strategies that will improve its thermal efficiency to the levels of conventional fuels. This paper focuses on the development of a liquid phase port-injection system for LPG, the design of a reference piston, and the baseline evaluation of the performance, combustion, and emissions characteristics of a single cylinder research engine to establish a benchmark comparable to existing LPG engines. A sweep of start of injection (SOI) timing is performed by injecting liquid LPG at several closed and open intake valve timings, which demonstrates no significant variation in engine performance, but accounts for a 10% reduction in bsCO with the optimal SOI timing. Spark timing sweep demonstrates the 50% burn crank angle location related to maximum brake torque (MBT) point with a brake thermal efficiency (BTE) of ~34% for the tested load case. The effect of equivalence ratio is also presented with optimal SOI timing at MBT condition. The engine starts exhibiting knocking combustion at 140kPa intake manifold air pressure (IMAP) with a peak torque of 253Nm and a 5% reduction in brake specific fuel consumption compared to the naturally aspirated scenario.
Fosudo, Toluwalase, Kar, Tanmay, Windom, Bret, Schlagel, Jacob, Olsen, Daniel
Applications of the Finite Element Analysis for Determination of Failure Safety Margins of the Design of the Honda CTX700 Motorcycle Front Braking System05-16-03-00162/15/2023
The purpose of this article was to determine the failure safety margins of the front braking system of a Honda CTX700 motorcycle and to perform a substantive stress analysis on the system, as well as to verify the stresses using FEMAP. It should be noted that in this finite element analysis (FEA), the connections between components are modeled using linear-contact connections that exert forces on adjacent surfaces and are not trivially meshed as one solid with coincident grids with two different section material properties. The first part of the work involved accurately measuring the geometry of each part and three-dimensional (3D) modeling of all components. Measurements were taken via the trivial methods of using a ruler and caliper, and then the 3D model was generated in Solidworks by digitizing the geometric parameters. Some parts of the system were simplified in the 3D model to ensure proper meshing of the model. Cavities and complex geometries, like fillets and chamfers, were simplified to avoid excessive computation times. Next, after modeling the geometry, the individual components (disk, caliper, pad, and brake bracket) were meshed and their respective material properties were assigned. A fine mesh was used for the components in order to best capture the geometry and to ensure a more accurate simulation of the parts. Most components were “Hex” meshed, except for the more complex geometry of the brake caliper and bracket. For these two components, load distribution was the main interest due to their bulk size in comparison to the other components and, as such, were “Tet” meshed with midside nodes. Material properties of the parts were determined through extensive research of the components via original equipment manufacturer (OEM) references. After meshing, the operating loads and boundary conditions were defined and applied to the model. Boundary conditions were provided while operating loads were calculated using formulas for disk braking torque and thermal temperatures. The FEA simulations were performed and the generated stresses were compared and correlated to the hand-calculated stress levels. The margins of safety (MS) were finally calculated by comparing the determined stresses against the material failure strengths. The approach was deterministic in gaining knowledge of what strength levels the braking system was designed for and accessible to the public.
Javidinejad, Amir, Orensztein, Hunter J., Ramirez, Marco, Berman, Jack
Brake Drum Qualification Recommended PracticeJ2686_202212 (Current)12/20/2022
This SAE Recommended Practice is intended for qualification testing for brake drums used on highway commercial vehicles with air brakes using an inertia-dynamometer procedure. This document consists of two distinct tests: Part A, durability and speed maintenance test, and Part B, heat check drag sequence test. Each test can be considered to be an independent evaluation of the brake drum which tests different properties.
Truck and Bus Foundation Brake Committee
Research on Regenerative Braking Control Strategy under High Charge State Using Prescribed Performance Prediction Control2022-01-704110/28/2022
To reduce the energy consumption level of electric vehicles, the working range of the regenerative braking system will gradually expand to the high state of charge of the battery. The time delay in the control signal transmission path of the high state of charge regenerative braking control process will affect the regenerative braking. At the same time, regenerative braking under a high state of charge puts forward higher requirements for the control accuracy of regenerative current. In the research of this paper, the motor model, battery model, and vehicle dynamics model are firstly established by using MATLAB/Simulink, and the dynamic relationship between regenerative current and regenerative braking torque is analyzed at the same time. Considering the system time delay, this paper proposes a high-charge regenerative braking control strategy (SPPC) that combines Smith prediction and prescribed performance control. This control strategy can not only compensate for the system time delay but also has a simple structure . It is convenient for engineering applications. Finally, the SPPC control strategy is effectively verified by the motor test bench.
Sun, Dongsheng, Zhang, Junzhi, He, Chengkun, Ma, Ruihai
Drum and Disc Brake Static Performance Test EquivalencyJ3192_202210 (Current)10/13/2022
This SAE Recommended Practice is intended for measuring the static brake torque performance of a pnuematically actuated brake assembly, friction material, and drum/disc combination on an inertia brake dynamometer.
Truck and Bus Brake Systems Committee
Brake Force Distribution Field Test Procedure for Truck and BusJ225_202210 (Current)10/7/2022
This SAE Recommended Practice provides a field test procedure and instructions for air braked single unit trucks, buses, and combination vehicles. Brake force distribution field testing with systems post-reduce stopping distance changes is still appropriate, however, vehicles with electronically controlled braking systems are not covered in this document and may need to be addressed in the future. It also provides recommendations for: a Instrumentation and equipment. b Vehicle preparation. c Test of air-braked single and combination vehicles. d Calculation of brake force distribution. e This test procedure is intended to be used as a field procedure. If a more refined method, utilizing laboratory equipment, is required, refer to SAE J1505.
Truck and Bus Brake Systems Committee
Enhancing Meta Model of the Brake Pad Friction Coefficient Using the Explainable Machine Learning2022-01-11759/19/2022
Recently, increasing system complexity and various customer demands result in the need for highly efficient vehicle development processes. Once the brake torque is predicted accurately during the driving scenario in the earlier stage, it will be able to prevent the changing the vehicle or brake system design to satisfy the legal regulation and customer requirement. As brake torque performance target allocate brake pad friction coefficient level and characteristic, the accurate friction coefficient prediction should be preceded for accurate prediction for brake torque. Generally, the friction coefficient of the brake pad is known to vary nonlinearly depending on the physical properties of the disc and the pad, as well as the brake disc rotational speed, the disc temperature, and the hydraulic pressure. Furthermore, it varies depending on the driving scenario even when other conditions are the same. Therefore, it is necessary to apply new methods to solve these challenges. In this study, new derivative variables are discovered by exploring the feature that is highly related with the brake pad friction coefficient. And then, MERF algorithm is selected to train the machine-learned meta model for consistently excellent predictive performance in the various driving scenarios. As a result, the overall predictive performance has been improved and achieved the target MAE. In addition, it was confirmed that the offset, discontinuity, and noise vulnerability of the prediction results also improved compared to previous studies. Most of all, it has been explainable that the causes of the brake pad friction coefficient changing. This meta model can predict the dynamic brake pad friction coefficient with changing brake disc rotation speed, disc temperature and hydraulic pressure input. It is also possible to predict the braking performance with varying friction coefficient according to the driving scenario when the meta model is integrated to the total vehicle simulation model.
Cho, Sunghyun, Bang, Sunghoon, Jang, Jiwoo, Kim, Youngjae
Concept Design of a Parking Brake Module for Standstill Management and Wheel Individual Brake Torque Generation for EVs with Unconventional Service Brake Topology2022-01-11869/19/2022
For electric vehicles the ability for regenerative braking reduces the use of friction brakes. Particularly on the rear axle of vehicles with reduced dynamic requirements such as urban vehicles, this can offer a potential for downsizing or, in extreme cases, even the elimination of the friction brakes on the rear axle. Due to the fact that the rear axle service brakes also represent the typical parking brake location in SoA (State-of-Art) vehicles, a rigorous rethinking of the parking brake concept is necessary to incorporate safe vehicle standstill management for such novel brake system topology. This research study introduces a novel parking brake design that covers SoA but also legal requirements while retaining potentials associated with the elimination of the rear service brakes such as cost and packaging. Also, the novel approach aims for a combination of traditional parking brake functionality and certain dynamic brake torques that are typically delivered by wheel individual service brake interventions. For instance, an uneven brake torque distribution to the wheels is desirable for accelerating on inhomogeneous road surfaces (μ-split situations), which is negatively affected by eliminating the service brakes. Beginning with a systematic comparison of multiple parking brake topologies that evaluates different locations for the parking brake in the driven axle’s powertrain, a promising approach is designed and dimensioned in detail.
Loss, Tobias, Peter, Simon, Verhagen, Armin, Görges, Daniel
Research on Vehicle Rollover Warning and Braking Control System Based on Secondary Predictive Zero-Moment Point Position2022-01-09163/29/2022
To solve the contradiction between model complexity and the warning accuracy of the algorithm of the vehicle rollover warning, a rollover state warning method based on the secondary predictive zero-moment point position for vehicles is proposed herein. Taking a sport utility vehicle(SUV) as the research object, a linear three-degrees-of-freedom vehicle rollover dynamics model is established. On the basis of the model, the lateral position of the zero-moment point and its primary and secondary rates of change are calculated. Then, the theoretical solution of time-to-rollover of the vehicles is deduced from the lateral position of the secondary predictive zero-moment point. When the rollover warning index, the lateral position of the zero-moment point, is greater than the set threshold, the active anti-rollover control system will be triggered. The active anti-rollover braking control system adopts a hierarchical control strategy. Taking the rollover warning index as the control target, the upper controller calculates the braking torque required by the front-outer wheel based on the Fuzzy Proportional Integral Derivative (PID) algorithm and the differential braking control strategy. The lower executive controller calculates the corresponding brake wheel cylinder pressure and inputs it to the corresponding wheel through the Electrical Hydraulic Brake(EHB), so that a certain additional yaw moment can be formed to prevent the vehicle from rolling over. Under some typical driving conditions, Carsim-Matlab co-simulation and real vehicle tests are carried out. The comparative test results show that the proposed rollover warning method based on the secondary predictive zero-moment point position can accurately and effectively predict the roll-over state of the vehicle, and the active anti-rollover braking control system can control the vehicle in time and effectively to prevent the vehicle from rollover.
Wang, Haiyang, Hou, Liming, Shangguan, Wen-Bin
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