Browse Topic: Brake-by-wire

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Safe State Definition and Verification for Distributed Multi-Controller EMB Architectures2026-01-08009/14/2026
The Electro-Mechanical Brake (EMB) system is an essential technology for safe braking in modern vehicles. However, the adoption of multi-controller architectures has introduced new challenges to conventional Safe State strategies. Traditionally, the Safe State defined in functional safety means "function shutdown," and in accordance with ISO 26262-1:2018 (Part 1: Vocabulary), aims for an "operational mode without risks exceeding reasonable levels." However, in the multi-controller architecture of EMB systems, the Fail-Operational Safe State concept is applied, where the system continues to provide limited functions even in the event of faults. It is essential to verify whether such operational modes actually satisfy the safety requirements of ISO 26262-3 and ISO 26262-4. This paper redefines the Safe State according to failure modes in EMB systems, analyzes system state transitions, and presents a coherence analysis methodology for validating the availability of resources required to provide limited functions in the Fail-Operational Safe State. Through this approach, potential design defects in multi-controller-based EMB systems can be detected early, validated across 1,149,952 fault scenarios with zero total-failure outcomes, and traceability of functional safety requirements can be established.
Kim, Kang San
Electro-Hydraulic Brake-by-Wire and Off-the-Shelf ABS Integration: Control Design and Hardware in the Loop Validation2026-01-07959/14/2026
This work presents the design of a control logic for an electro-hydraulic brake-by-wire in series with an off-the-shelf ABS unit for motorsport applications. Validation is performed through hardware-in-the-loop testing with a complete hydraulic layout, including the brake-by-wire actuator, the ABS module, and brake calipers. State of the art electro hydraulic brake-by-wire systems are increasingly adopted in top level motorsport and are now transitioning to high performance road vehicles, in combination with ABS and ESC. However, due to motorsport regulations, racing brake-by-wire systems do not incorporate ABS functionality. To combine the performance of motorsport grade actuators with the ease of use required for non professional drivers, a series configuration between brake-by-wire and ABS represents a natural solution. This architecture is also relevant for future road vehicle applications, offering additional redundancy for autonomous driving ready systems. A dedicated hardware-in-the-loop test rig has been developed to perform experimental testing of the complete brake system. Wheel dynamics are simulated in real-time using a single-axle vehicle model, and wheel speed signals are reproduced via a sensor emulator. Preliminary tests show that the original pressure-based brake-by-wire control strategy exhibits poor performance during ABS activation, as ABS operation significantly alters system behavior. To address this issue, an improved control strategy is proposed, introducing a dedicated control mode activated during ABS operation, with a smooth transition back to nominal control once ABS activity ceases. Experimental results demonstrate that the proposed strategy maintains closed-loop stability, avoids excessive pressure oscillations and piston end stop conditions, and, most important, does not interfere with ABS operation. Overall braking performance is fully preserved.
Milivinti, Massimiliano, Gimondi, Alex, Gobbi, Massimiliano, Cantoni, Carlo
A Study on TSC (Technical Safety Concept) Design and Verification in EMB (Brake by Wire) Systems2026-01-08019/14/2026
The Electro-Mechanical Brake (EMB) system is a dry-type Brake-by-Wire technology that eliminates hydraulic components and directly controls friction braking using electrical actuators at each wheel. The EMB architecture consists of a Main Center Control Unit, a redundant Backup Center Control Unit, and four Wheel Control Units communicating via CAN FD. Due to its direct involvement in vehicle braking, compliance with ISO 26262 functional safety requirements is critical. As system complexity increases, potential risks such as hardware failures and communication faults must be systematically addressed. The proposed TSC was developed according to ISO 26262, covering the concept phase (Part 3), system-level development (Part 4), and software implementation (Part 6). Safety goals and Functional Safety Requirements derived from HARA are used to guide system architecture design and TSC development. Key design principles include modularity, redundancy, fault detection, and fail-safe operation. Verification is conducted at both system and vehicle levels using ECU-in-the-Loop Simulation (EILS), Hardware-in-the-Loop Simulation (HILS), and real-vehicle tests. Fault scenarios, including Main Center Control Unit failures and CAN communication losses, are injected using a custom LabVIEW-based fault injection tool. The study evaluates Fault Tolerant Time Interval (FTTI) settings, error handling mechanisms, and control handover strategies under fault conditions. The results show that redundancy and localized communication enable stable operation and smooth control transfer within the FTTI window without noticeable impact on braking performance or driver awareness. This study demonstrates the robustness of the proposed EMB architecture. Future work will focus on prognostics and maintenance strategies to support safe deployment in autonomous and electric vehicles. [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Kim, Dokun
Physics-Informed Machine Learning Digital Twin of Electro-Mechanical Brakes for Clamp-Force and Friction Estimation2026-01-08069/14/2026
Recently, there has been a drastic shift in the industry towards wire architectures like steer-by-wire and brake-by-wire. For safe and accurate force control, diagnostics, and consistent performance over the operating envelope, accurate plant modeling of the Electro-Mechanical Brake (EMB) is important. Classical approaches involved linearized dynamic EMB models and the use of the characteristic stiffness curve for calibration at the operating points. These methods often perform poorly over regions where hysteresis, compliance, and friction are strongly nonlinear. Prior research on state or force estimation for EMB has focused on pad contact detection, thermal adaptation, and hysteresis-aware clamp force estimation. However, there are still accuracy gaps in practical applications during transients and under shifting friction regimes. In this work, a digital twin based on Physics-Informed Machine Learning is introduced, following the governing dynamics of the actuator-caliper assembly of EMB while learning (i) a physically significant parameter—system damping (Bsys) and (ii) a non-linear friction term constrained as a function of the actuator motion states and operating conditions. Non-linear friction is captured through gray-box friction formulation and learning unmodeled residual dynamics such as hysteresis and backlash. An EMB test stand is used to collect steps, ramps, holds/engagements, APRBS, and swept-sine excitations, with signals including time-aligned force command, motor torque/current, actuator position/velocity, and pad force measurement from a force sensor for model training. Results demonstrate a decrease in pad-force prediction error, along with non-linear and residual friction estimation. The resulting digital twin can enable sensor-less force estimation, friction compensation design, predictive analytics, and health monitoring through tracking parameter drift and friction signatures.
Rai, Prakhar, Gadhvi, Tirth
Architecting Safety-Critical Systems for AI-Enabled Software-Defined Vehicles: A Compute, Timing, and Isolation Framework with a Brake System Case Study2026-01-08119/14/2026
Software-defined vehicle (SDV) platforms are reshaping safety-critical system design by consolidating braking and other motion-control functions on centralized heterogeneous edge compute that also executes physical-AI workloads. This consolidation breaks traditional assumptions of fixed ECUs and simple timing envelopes, complicating assurance of determinism, isolation, and fail-operational behaviour for ASIL-D brake functions. Building on a decentralized brake-by- wire (BbW) architecture with dual controllers, redundant low-voltage power grids, and smart electromechanical brake corner actuators, this paper proposes a systems-level framework for architecting safety-critical functions in AI-enabled SDVs along three dimensions: compute, timing, and isolation. The framework classifies conventional and AI-based functions and maps them to heterogeneous compute classes; defines architectural patterns that combine safety islands, power-domain redundancy, and hardware partitioning to support freedom from interference; and formalizes timing domains and contracts that bound latency, jitter, and failover dynamics across sensors, centralized controllers, and decentralized actuators. The contribution is not a new AI algorithm, but a safety-oriented architectural framework that constrains how AI-enabled functions may be integrated into fail-operational by-wire systems. A BbW case study with edge-resident AI observers and anomaly detectors shows how the framework complements System Analysis Tool (SAT)– based failure modelling and clarifies trade-offs among safety isolation, latency, and AI performance while preserving braking safety guarantees under continuous software evolution.
Srinivasaraghavan, Soumyasudharsan
Stability Control Strategy for Vehicles under Single-Wheel Brake-by-Wire Failure Conditions2026-99-11269/11/2026
The electromechanical brake-by-wire (EMB) system offers advantages such as high braking accuracy, fast response, and compact structure, and has become a major development direction for electric vehicles. However, the lack of necessary redundancy limits its large-scale application. Therefore, a stability control strategy is proposed, which is implemented at the algorithm level. According to braking intensity, the brake failure scenarios are classified into three levels: mild, moderate, and severe. For mild braking, a brake-force reconstruction strategy is adopted to compensate for the failed wheel. For moderate braking, a combined brake-force reconstruction and fuzzy sliding-mode steering control strategy is employed for active front-wheel steering. For severe braking, a brake-force reconstruction and model predictive control (MPC)-based active steering strategy is applied to achieve precise control of vehicle stability. The results show that the control strategy effectively compensates for single-wheel brake failure and ensures vehicle safety and stability across different braking intensities.
Zhang, Yi-long, Li, Shicheng, Xu, Lin
Research on the Performance Evaluation Method of Intelligent Chassis Vehicles Based on AHP2026-99-08617/30/2026
The comprehensive performance evaluation system for intelligent chassis vehicles comprises multi-level indicators and exhibits certain complexity. In this study, the Analytic Hierarchy Process (AHP) is employed to calculate the weights of indicators across different performance levels. Comprehensive performance is evaluated through the integration of objective indicator assessment and subjective scoring, and the evaluation results of the vehicle’s comprehensive performance are ultimately derived. This work provides a scientific scoring method for the product testing and evaluation of intelligent chassis vehicles.
Wu, Shiyu, Wang, Jingxian, Guo, Ruiling, Liang, Dong, Li, Saisai, Yu, Xuetian
Research on Vehicle and Longitudinal Tire Model Parameters Identification Based on Electro-Mechanical Brake System2026-01-06344/7/2026
The Electro-Mechanical Brake (EMB) system is a novel type of brake by wire systems with independently controllable characteristics. This system aids in the decoupling analysis of the vehicle and actuator dynamics, thereby improving the accuracy of parameter identification. Therefore, this paper proposes an innovative parameter identification method for vehicle parameters and longitudinal tire model parameters, based on the characteristics of the EMB system and onboard sensors. First, based on the wind resistance and rolling resistance coefficients obtained from the vehicle coasting conditions, a decoupled constant clamping force sequence braking condition for the front and rear axles is designed by integrating the characteristics of the EMB actuator and vehicle dynamics. This approach enables the identification of vehicle and nonlinear longitudinal tire model parameters, significantly improving the accuracy of parameter identification. Next, considering the nonlinear characteristics of the longitudinal tire model, a factorial experiment is conducted to analyze the impact of the Particle Swarm Optimization (PSO) optimization algorithm parameters on the identification process from three perspectives: iteration count, computation time, and optimal function value. Furthermore, the effectiveness of three PSO variants: the Compressed Factor PSO (CF-PSO), the Adaptive Weight PSO (AW-PSO), and the Hybrid PSO (H-PSO), was investigated for identifying the nonlinear characteristics of the longitudinal tire model. Finally, through data simulation and real-vehicle experiments on both high-adhesion and low-adhesion roads, the effectiveness and accuracy of the proposed vehicle parameter and longitudinal tire model parameter identification method based on EMB system characteristics are verified through a comprehensive evaluation of multiple indicators, and the method’s validity is further confirmed using data backfill and model benchmarking.
Huang, Jiayi, Cheng, Yulin, Zhuo, Guirong, Le, Qiao, Wei, Wei, Shu, Qiang
Modular 3-D Lumped-Parameter Thermal Network for Thermal Estimation of Permanent-Magnet Synchronous Motors in Electromechanical Braking Systems2026-01-01364/7/2026
As electric intelligent vehicles advance, drive-by-wire systems are increasingly adopted, and the thermal reliability of electromechanical brake (EMB) motors—the key actuators—remains safety-critical. Under stalled-rotor operation, unequal DC currents are typically applied to the three phases, producing nonuniform winding heating. Conventional thermal models can miss the associated tangential heat-transfer effects, increasing the risk of phase-wise end-winding hot spot. This paper analyzes EMB motor thermal behavior under stalled-rotor conditions using a modular 3-D lumped-parameter thermal network (LPTN). First, a standardized tooth module with external interfaces is developed. Its internal parameters are informed by experiments and computational fluid dynamics (CFD) and identified via particle swarm optimization (PSO), allowing the module to be encapsulated for reuse. Next, based on the machine topology, a minimal motor is derived and multiple tooth modules are interconnected through common nodes to form a modular 3-D LPTN that resolves radial, axial, and tangential heat-flow paths. Finally, a stepwise, weighted PSO is applied—module level followed by system level—to calibrate the full network. The tooth-module abstraction also enables rapid network assembly, and the boundary-cooling and loss-allocation modules can be updated to accommodate different cooling architectures and heating patterns while retaining the same internal formulation. Bench tests with inhomogeneous three-phase heating, validated against three-phase end-winding thermocouple measurements, show that the proposed model predicts temperatures more accurately than existing LPTNs. These results indicate that explicitly accounting for tangential heat exchange can improve temperature prediction for EMB motors under stalled-rotor duty and provides a reusable template for other concentrated-winding machines subject to nonuniform thermal loading.
Duan, Yanlong, Xiong, Lu, Wang, Xinjian, Zhuo, Guirong, Zeng, Jie
Active Thermal Management of EMB Motors Considering Winding Heat Imbalance2025-01-733112/31/2025
The electro-mechanical brake (EMB) system represents a novel dry brake-by-wire technology renowned for their superior control performance and compact structure, effectively meeting the demands of intelligent electric vehicles. However, its performance can be compromised under extreme ambient temperatures and non-uniform heat generation across the coils. This study addresses the critical challenge of single-phase overheating in the EMB motor actuator during low-speed high-torque operations by proposing a novel Maximum Duration Per Torque (MDPT) control strategy. The core of this method is to optimize the allocation of dq-axis currents. It aims to extend the safe operating duration of the EMB while respecting its thermal constraints and maintaining full braking performance. Firstly, based on the operational characteristics of the EMB, we establish a lumped parameter thermal network (LPTN) model. This model accurately captures the uneven thermal distribution among the three-phase windings and enables real-time prediction of the remaining safe operating time under various current distributions per phase. Using a sequential quadratic programming (SQP) algorithm, we efficiently compute the optimal d- and q-axis current references that maximize this duration. A triple-loop controller based on the MDPT algorithm is designed and validated through simulations and experiments. Results show that the proposed method significantly extends the safe operating time compared to conventional Maximum Torque Per Ampere (MTPA)-based strategies. This study shows that effective thermal management of electromechanical brake systems, implemented through the design of control algorithms, which ensures the durability of the system and the reliability of driver safety, is achievable.
Zeng, Jie, Xiong, Lu, Zhuo, Guirong, Duan, Yanlong, Wang, Xinjian
A Unified Layer-by-Layer Progressive Framework for Sensorless Control of Brake-By-Wire Systems2025-01-732812/31/2025
Conventional control of Brake-by-Wire (BBW) systems, including electro-hydraulic brake(EHB) and electro-mechanical brake(EMB), relys on pressure sensors, the errors of which usually resulted inaccurate braking force tracking bringing a lot of safety hazards, e.g., wheel locking and slipping. To address challenges of accurate braking force control under the circumstance of the system nonliearities (such as friction) and uncertainties (such as stiffness characteristics) for a sensorless BBW system, this paper proposes a unified Layer-by-Layer Progressive (LLP) control framework to enable fast and precise brake control. The work has been conducted with three new contributions in the three cascaded stages within the control framework: in the coarse compensation stage, a load-adaptive LuGre friction model is proposed to handle modellable nonlinearities; in the fine compensation stage, an Adaptive Extended Disturbance Observer (AEDO) is developed to estimate and compensate for parameter uncertainties and external disturbances; and in the fine control stage, a cascaded nonlinear controller is designed to suppress unmodeled dynamics and residual disturbances. Through real-vehicle experiments, the proposed LLP method has been validated under both pulse and gradual braking conditions for BBW systems (include EHB and EMB systems). Under pulse braking conditions, the proposed method yields maximum response errors of 1.2bar for the EHB system and 6.3% for the EMB system. Under gradual braking conditions, the steady-state errors are 0.7bar for EHB and 1.74% for EMB. These results empirically confirm the effectiveness and robustness of the proposed method.
Zhou, Quan, Lv, Zongyu, Han, Wei, Li, Congcong, Zhao, Xinyu, Xiong, Lu, Shu, Qiang
Research on Wheel Slip Ratio Control for Electro-Mechanical Brake System: From PI to High-Order Sliding Mode Control2025-01-733212/31/2025
The electro-mechanical brake (EMB) system is a novel dry-type brake-by-wire system that features superior control performance and a compact structural design, effectively meeting the development demands of intelligent and electrified vehicles. However, current research on anti-lock braking system (ABS) primarily focuses on hydraulic brake system and mostly remains at the simulation and hardware-in-the-loop testing stages. Therefore, this paper validates the feasibility of slip ratio control based on EMB actuators through both simulation and real-vehicle experiments. First, this paper establishes an equivalent second-order response model for the closed-loop EMB control system through theoretical derivation and identifies the dynamic response characteristics of the EMB actuator via sinusoidal frequency sweep testing. Next, it compares two control strategies: one that uses the reference slip ratio as the direct control target, and another that uses reference wheel speed as the direct control target to indirectly regulate slip ratio. The latter effectively avoids the nonlinearities in slip ratio control caused by variations in vehicle speed. Based on reference wheel speed control, three types of slip ratio controllers were designed and derived: proportional-integral control (PI), integral sliding mode control (ISM), and super-twisting integral sliding mode control (STISM). Finally, simulation and real-vehicle tests on high-adhesion road surfaces verified that sliding mode slip ratio control based on reference wheel speed offers robustness, avoids the risks associated with overestimated controller gains, and improves the overall stability of the control system. In particular, the STISM, as a representative of high-order sliding mode control, effectively addresses the chattering issue present in traditional first-order sliding mode methods, offering enhanced braking safety and comfort.
Cheng, Yulin, Qiao, Le, Wang, Chenyu, Li, Congcong, Zhuo, Guirong, Wei, Wei
Actuator-to-Vehicle Joint Estimation of Clamping Force for Sensorless Control of the Electro-Mechanical Brake System2025-01-03389/15/2025
The electro-mechanical brake (EMB) is a promising brake actuating system for electrified vehicle. To enhance the system function safety while saving space from redundancy sensors, this paper studied sensorless climbing force control for the EMB where a new climbing force estimator is proposed by fusing the information from vehicle dynamics and EMB states. The work was done with three contributions: 1) The priori clamping force characteristics were implemented to build the estimator with two parallel models, one of which was derived from the actuator rigid-body dynamics while the other was derived from vehicle longitudinal dynamics model; 2) a proportional-integral (PI) observer utilizing wheel speed residual signals was developed to correct the initial estimates iteratively; 3) a fuzzy control controller was proposed to optimize the key parameters of the PI observer. Comparative study was conducted on a co-simulation platform and the results showed that the actuator-to-vehicle joint estimation method can reduce more than 28% root mean square error (RMSE) compared with the conventional actuator model-based estimation method by utilizing PI observer. After the optimization of key parameters, the optimal ratio can reach 32%. Robustness analysis demonstrated that the climbing force estimations accuracy across the studied distinct braking scenarios were consistency.
Xing, Yipu, Zhou, Quan, Cheng, Yulin, Li, Congcong, Han, Wei, Zhuo, Guirong, Xiong, Lu
Applying Specialized System Analysis for Brake by Wire in Software Defined Vehicles: The Development of a System Analysis Tool (SAT)2025-01-03559/15/2025
The emergence of Software Defined Vehicles (SDVs) has introduced significant complexity in automotive system design, particularly for safety-critical domains such as braking. A key principle of SDV architecture is the centralization of control software, decoupled from sensing and actuation. When applied to Brake-by-Wire (BbW) systems, this leads to decentralized brake actuation that demands precise coordination across numerous distributed electronic components. The absence of mechanical backup in BbW systems further necessitates fail-operational redundancy, increasing system complexity and placing greater emphasis on rigorous system-level design validation. A comprehensive understanding of component interdependencies, failure propagation, and redundancy effectiveness is essential for optimizing such systems. This paper presents a custom-built System Analysis Tool (SAT), along with a specialized methodology tailored for modeling and analyzing BbW architectures in the context of SDVs. The operation of the SAT is described in detail, and its application is demonstrated through illustrative examples derived from a representative BbW system model. The SAT enables systematic evaluation of individual component failures, their logical and functional interdependencies, and the cumulative impact of multiple simultaneous faults. It provides structured, data-driven insights that support early trade-off decisions between cost, complexity, and safety, and facilitates the generation of robust, traceable functional requirements. Additionally, the SAT quantifies the relationship between component failure rates, expressed in Failures in Time (FIT), and system-level performance degradation across multiple defined operational states. By enabling a rigorous, model-based approach to design exploration and fault analysis, the SAT enhances system engineers' ability to validate fail-operational behavior, identify design weaknesses, and refine brake system architecture. This supports a more efficient development process for safety-critical systems and contributes to the overall reliability and performance of BbW implementations within SDV platforms.
Heil, Edward, Zuzga, Sean, Babul, Caitlin
Enhancing Robustness of Electro-Hydraulic Brake-by-Wire Actuators via Linear Active Disturbance Rejection Control2025-01-03419/15/2025
In recent years, motorsport has increasingly focused on environmental concerns, leading to the rise of hybrid and fully electric competitions. In this scenario, electric motors and batteries take a crucial role in reducing the environmental impact by recovering energy during braking. However, due to inherent limitations, motors and battery cannot fully capture all braking power, necessitating the use of standard friction brakes. To achieve an efficient balance between electric motors and friction brakes, the brake pressure can no longer be directly controlled by the driver. Instead, it must be computed by the Vehicle Control Unit (VCU) and sent to a smart actuator, i.e. the Brake-By-Wire (BBW), which ensures that the required pressure is applied. The standard approach to achieve precise pressure control is to design a nested Proportional-Integral-Derivative (PID) control architecture, which requires an accurate nominal model of the system dynamics to meet the desired tracking performance. However, in motorsport applications, actuator dynamics are complex to identify, car-dependent, and, most importantly, time-varying due to factors like temperature changes and wear. These challenges make PID controllers based on nominal models less robust, both in terms of stability and tracking performance. To address these challenges, this paper proposes a robust architecture based on a cascade Linear Active Disturbance Rejection Control (LADRC) scheme for an electro-hydraulic actuator. The architecture consists of an inner loop, based on a second-order LADRC, which controls the piston position, and an outer loop, which employs a first-order LADRC to regulate the pressure. Compared to standard PID controllers, the LADRC approach promises two key advantages: it is faster and easier to tune while offering increased robustness. The proposed control scheme is experimentally validated on a test bench using a state-of-the-art BBW system and a racing car hydraulic line highlighting an increased robustness compared to a standard PID scheme.
Gimondi, Alex, Dubbini, Alberto, Riva, Giorgio, Cantoni, Carlo
Active Online Estimation of the Electromechanical Brake Coulomb Friction2025-01-03429/15/2025
Electro-mechanical braking (EMB) system has emerged as a potential candidate that serves the brake-by-wire technology. Several mechanisms are used to transmit the clamp force, where each has efficiency losses due to static friction and viscous damping. Compensating these losses is essential for accurate responses such that meeting the performance goal and improving the stopping distance of the EMB. Mathematical and empirical models are used to estimate these losses so that clamp force is accurately estimated and controlled. However, none of these models are capable of addressing the part-to-part variation or predicting the impact of other noise factors on these losses such as operating temperature and degradation. The purpose of this work is to online estimate the EMB coulomb friction by introducing an external torque command over a period of time while observing the system’s response. This approach continuously measures the coulomb friction while the system is in normal operation which allows for dynamic compensation for these losses leading to more accurate clamp force controls for EMB. In this EMB system, after each brake release, the inner pad is retracted to a pre-defined position, where an air gap is controlled to prevent drag. The algorithm considers safety aspects, hence, it is designed to operate right after the home position is achieved and only while system is in clearance state avoiding the possibility of drag. The simulation and experimental results showed relatively accurate estimation for the coulomb friction of different operating temperatures and parts conditions.
Aljoaba, Sharif, Ramakrishnan, Raja, Dobbs, Jeremy
Longitudinal Dynamic Metrics for Describing and Developing the Deceleration Behavior of Vehicles in the Concept Phase2025-01-02647/2/2025
The brake system is a critical safety component in motor vehicles. Advances in the electrification of the powertrain and the rise of autonomous driving technologies are significantly impacting the brake system, which allows innovative approaches and necessitating the development of new brake concepts and new deceleration strategies. A major technological advance is the decoupling of the driver from the brake system through Brake-by-wire technology. A crucial attribute of Brake-by-wire systems is the attainment of a concept-independent deceleration behavior. To establish a consistent and brand-specific deceleration behavior in the early development phase, objective metrics and perceptual thresholds are required to describe the desired subjective braking behavior. Moreover, objective metrics are indispensable for the virtual phase of the vehicle development process. This article focuses on deceleration from a straight-ahead drive. To identify objective metrics and perceptual thresholds, a testing procedure and a set of potentially robust metrics are first defined based on literature, expert knowledge, and specific driving characteristics related to deceleration. Suitable metrics and perceptual thresholds are then derived from a subjective evaluation study, objective measurements, and subsequent correlation analysis. As a result, objective metrics for steady-state deceleration, deceleration build-up time and deceleration built-up were established. A subsequent benchmark of current vehicles demonstrates the applicability of the identified criteria.
Biller, Ralph, Udovicic, Matej, Ketzmerick, Erik, Kirch, Sebastian, Mayr, Stefan, Prokop, Günther, Wagner, Andreas
Braking Force Distribution Strategy for Brake-by-Wire Systems: Enhancing Safety and Redundancy10-09-03-00286/9/2025
Brake-by-wire (BBW) systems, characterized by fast response, high precision, ease installation, and simplified maintenance, are highly likely to become the future braking systems. However, the reliability of BBW is currently inferior to that of traditional hydraulic braking systems. Considering ECE R13 regulations, actuator reliability, and braking efficiency, this article first proposes a new braking force distribution strategy to prevent braking failure and enhance vehicle safety without modifying the actuator itself. The strategy reduces the operating frequency of rear actuators during low- and medium-intensity braking, thereby extending their service life and operational reliability. Then, the co-simulation model combining Simulink and AMESim was established for simulation validation based on direct drive braking actuator. Additionally, the real-vehicle test platform was built for typical braking scenarios. The simulation and experimental results show that this strategy significantly reduces the operating rate of rear actuators while maintaining braking performance. This ensures that the rear actuators have a longer service life and can be used for emergency braking. In the event of front actuators’ failure, the rear actuators can provide the necessary and emergency braking force, thereby enhancing the overall safety of the vehicle.
Li, Tianle, Gong, Xiaoxiang, He, Chunrong, Deng, Zhenghua, Zhang, Hong, Xu, Rong, He, Haitao, Wang, Xun, Zhang, Huaiyue
Letter from the Guest Editors10-09-02-00095/19/2025
Letter from the Guest Editors
Wang, Zhenfeng, Zhang, Yunqing, Qi, Ronghuai, Lu, Yukun
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
A Control and Fault-Tolerant Strategy Based on Electromechanical Brake System2025-01-82654/1/2025
With the development of automotive electrification and intelligent technology, vehicles have higher and higher requirements for braking systems. On the one hand, it requires it to have an active braking function, and at the same time facilitates the integration with other control systems of the chassis domain. The system should minimize oil pollution as much as possible, and under the premise of ensuring the pedal force, it can be used to recover the brake energy as much as possible to improve the range of electric vehicles as possible. The new brake system based on Electronic mechanical brake (EMB) as a line -controlled decoupling braking system can not only meet the needs of the brake pedal sensation, but also achieve continuous and accurate control of braking power. It can effectively Taking into account braking economy, braking safety, and braking comfort. In addition, the development of EMB technology is still immature and the failure rate is high, so research on EMB's fault tolerance control research is very meaningful. This study mainly conducts research on electronic mechanical braking system control strategies. First of all, the EMB execution agency is selected, designed and calculated, and systematically models. Secondly, the EMB multi -stage closed -loop control strategy was designed based on the permanent magnet synchronous motor vector control method. Finally The design-based braking moment distribution strategy is designed, and the effectiveness of EMB control strategy and failure control is verified by Simulink simulation.
Li, Xuesong, Qin, Keyun, Zheng, Hongyu, Kaku, Chuyo
A Nonlinear Characteristics Identification and Compensation Control Method for Electromechanical Brake System2025-01-88104/1/2025
Clamping force control in Electromechanical Brake (EMB) systems must overcome various nonlinear characteristics, such as motor distorted voltage, Back Electromotive Force (EMF), and actuator friction disturbances. Therefore, modeling and parameter identification of these nonlinearities are necessary. This paper first proposes a motor parameter identification method based on the mathematical model of a Permanent Magnet Synchronous Motor (PMSM). A combination of the Least Square Method and Particle Swarm Optimization (PSO) is used to stepwise identify both the electrical and mechanical parameters of the motor. The accuracy of the identified parameters is validated by comparing simulation results with test bench responses. The identified parameters are applied to design the motor Back EMF compensation module, the distorted voltage compensation module, and to tune the current loop parameters. Next, a lumped parameter friction model suitable for closed-loop clamping force control in EMB systems was established, and specific operating conditions for identifying friction parameters were designed. The feasibility of this identification was validated through simulation analysis. Finally, a closed-loop clamping force control strategy based on friction compensation was developed. The proposed method is applied to the clamping force control system of a vehicle equipped with four-wheel EMB. Experimental results demonstrate that the stepwise parameters identification method for both motor and actuator effectively improves the response speed and accuracy of EMB clamping force control.
Qiao, Le, Xiong, Lu, Zhuo, Guirong, Shu, Qiang
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
Concept of an Electromechanical Brake-By-Wire System for Battery-Electric Vehicles2025-01-88044/1/2025
Brake-by-wire systems have received more and more attention in the recent years, but a close look on the available systems shows, that they have not reached full by-wire level yet. Most systems are still using hydraulic connections between main cylinder and the brake calipers on at least one axle to ensure functional safety. Mostly, this is the front axle, since the front brakes have to convert more kinetic energy during braking manoeuvers. Electromechanical actuators are currently used for rear brakes in hybrid brake-by-wire applications solely, since a loss of the front brake calipers can lead to severe conditions and control loss of the vehicle during braking. Further, the higher mass of battery electric vehicles (BEVs) leads to much higher braking forces on both axles and to increased sizes of the electromechanical calipers. This article presents a concept for a brake-by-wire system for battery electric vehicles, which features electromechanical brake actuators on all corners and a redundant system architecture. Theoretically, the proposed system is capable to generate a braking intensity up to 70% for vehicles with a total mass of approximately 2.8 tons. Besides mechanical design of the actuator, the power electronics are taken into account too and their behavior is investigated through dedicated simulation.
Heydrich, Marius, Lenz, Matthias, Ivanov, Valentin, Stoev, Julian, Lecoutere, Johan
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
Feedforward Control of Clamping Force in Electronic Mechanical Brake System Based on Inertia Identification and Load Torque Observation2025-01-70511/31/2025
The braking system is an essential element for ensuring the safe operation of vehicles. This research investigates the influence of electronic mechanical brakes on the control performance of permanent magnet synchronous motors, with a particular focus on variations in the load torque and inertial load. This study addresses challenges such as delayed responses in the clamping force and diminished control accuracy. To mitigate these issues, a Luenberger load torque observer is utilized for the real-time identification of load torque. The identified load torque is subsequently converted into a compensation current, which is integrated into the current loop as a feed-forward compensation signal to enhance the control performance. Additionally, to reduce the impact of variations in inertial load on the overall control system, this study employs a model reference adaptive algorithm for the online identification of rotational inertia, with the identification results being fed back to the load torque observer. The efficacy of this approach was validated through the development of a corresponding simulation model. Simulation outcomes indicate that the proposed strategy for identifying rotational inertia and implementing load torque feed-forward compensation significantly enhances the accuracy of clamping force control and the system's resistance to interference in electromechanical brakes, thereby offering a novel technical pathway for achieving high-precision brake control.
Wan, Xiaobo, Shang, Ruipeng, Li, Yingchun
Modeling and Simulation of an Electromagnetic Brake-by-Wire System for Formula SAE Vehicles2024-36-016912/20/2024
Electric vehicles represent a shift towards sustainability in the automotive industry, with the Brake-by-Wire (BBW) system as an innovation to enhance safety, and performance. This study proposes an electromagnetic BBW system for Formula SAE vehicles, optimizing an electromagnet with a genetic algorithm as the actuator. Through a selection process from a million individuals, the system was modeled. Integrated with electric motors using CarMaker® software, the optimized electromagnet surpassed the minimum required force of 228.08 N without reaching its nominal current of 12.5 A, achieving a force of 231.1 N for 150 W power, indicating an energy efficiency of 0.706 N/Watt. The system also exhibited a response time of 17.92ms for an 80 bar increase, 1.52 times better than compared systems. Simulation under varying braking intensities demonstrated dynamic behavior, with settling times for slow, moderate, and sharp braking at 193 ms, 62 ms, and 21 ms, respectively. Efficiency during different braking scenarios yielded energy recovery rates of 33.25%, 8.18%, and 5.34%, respectively. These results validate the proposed system.
Salgado, Vinícius Batista Alves, Gomes, Deilton Gonçalves, Andrade Lima, Cláudio
Research on Direct-Drive Brake Actuator and Its Control Method for Electric Vehicles10-09-01-000311/8/2024
With the rapid development of electric vehicles, the need for improved reliability and safety performance of electric vehicle braking systems has become paramount. In response to this demand, a novel direct-drive brake-by-wire actuator based on linear motors was designed to address these challenges. This article presents the structure and principles of the proposed braking actuator. Leveraging the traditional electromechanical brake systems as a foundation, the prototype was modified and fabricated. Additionally, the control and drive system for the braking actuator was established using the TMS320F28335 digital signal processor. Moreover, the current-position dual closed-loop control algorithm was devised to regulate the braking force accurately. Experimental results demonstrate that the direct-drive brake-by-wire actuator exhibits rapid responsiveness and precise braking force modulation, showcasing promising prospects in the field of electric vehicle braking.
He, Haitao, He, Chunrong, Gong, Xiaoxiang, Deng, Zhenghua, Li, Tianle, Wang, Xun, Zhang, Hong, Xu, Rong
Safety Concepts for Future Electromechanical Brake Central Control Systems15-18-01-000410/25/2024
Electromechanical brakes (EMB) are currently coming into focus in the automotive industry. This trend was confirmed in 2022, when a first automotive supplier [1] announced the series production of EMB systems. One major driver is safety, especially if EMB systems are implemented with smart actuators that install redundant electronic control units (ECU) and distributed software [1]. Earlier, the authors have addressed safety mechanisms in EMB actuators [2]. In this article the authors extend their investigation to address safety mechanisms in future EMB central control systems (CCS). Impact of different brake system topologies (X-, H-, centralized) vis-à-vis potential safety mechanisms within communication buses and ECUs is analyzed.
Schrade, Simon, Röhler, Andreas, Nowak, Xi, Verhagen, Armin, Schramm, Dieter
Understanding the Actuation Point Stiffness of Electromechanical Drum Brakes15-18-01-00029/24/2024
Electromechanically actuated drum brakes are one interesting option for the realization of brake-by-wire systems for future electric vehicles. A key characteristic for the design and control of electromechanical brake actuators is the actuation point stiffness, as this quantity relates the actuation force to the required actuator position. The various known approaches for the control of electromechanical brakes, which primarily focus on disc foundation brakes, typically rely on the stiffness curve at least to some extent. A transfer of these approaches to drum brakes is not straightforward, because the actuation point stiffness for drum brakes is much more complex compared to disc brakes. In particular, a strong hysteretic behavior is observed for the standing drum and a considerable change of the stiffness and hysteresis can be observed for the rotating drum. Although drum brakes have been used for decades these effects have not been thoroughly discussed in literature, yet. Hence, this article proposes a minimal model, which gives a fundamental understanding of the stiffness characteristics of drum brakes. The relation to measured stiffness curves is discussed in detail to provide an in-depth understanding of the drum brake behavior. Additionally, prospect is given to a reduced complexity model that is suitable for online identification and control.
Peter, Simon, Janhsen, Michael, Stümke, Daniel, Görges, Daniel
Design, Modeling, and Control of Electronic Mechanical Brake System: A Review10-08-04-00268/28/2024
The electronic mechanical brake (EMB) system is a critical actuator for achieving brake-by-wire control. This review categorizes and summarizes the literature related to EMB into three sections: actuator, mathematical modeling, and control strategies. In the actuator aspect, this article compares and analyzes motors, motion conversion mechanisms, and self-reinforcing mechanisms. For mathematical modeling, this article reviews modeling methods for EMB systems concerning motors, transmission mechanisms, friction, contact collisions, nonlinear stiffness, and hysteresis characteristics. Regarding control strategies, this article consolidates methods for clamp force control, clamp force estimation, and gap management. Finally, the article discusses potential future research directions in EMB from both hardware structure and software algorithm perspectives.
Yan, Zhoudong, Peng, Hang, Chen, Xinbo, Yan, Min
Information on Brake-By-Wire (BBW) Brake Control SystemsAIR5372A (Current)5/14/2024
This SAE Aerospace Information Report (AIR) describes the design approaches used for current applications of aircraft Brake-by-Wire (BBW) control systems. The document also discusses the experience gained during service, and covers system, ergonomic, hardware, and development aspects. The document includes the lessons that have been learned during application of the technology. Although there are a variety of approaches that have been used in the design of BBW systems, the main focus of this document is on the current state of the art systems.
A-5A Wheels, Brakes and Skid Controls Committee
Gap Adjustment Strategy for Electromechanical Brake System Based on Critical Point Identification2024-01-23204/9/2024
Abrasion of the Electromechanical brake (EMB) brake pad during the braking process leads to an increase in brake gap, which adversely affects braking performance. Therefore, it is imperative to promptly detect brake pad abrasion and adjust the brake gap accordingly. However, the addition of extra gap adjustment or sensor detection devices will bring extra size and cost to the brake system. In this study, we propose an innovative EMB gap active adjustment strategy by employing modeling and analysis of the braking process. This strategy involves identifying the contact and separation points of the braking process based on the differential current signal. Theoretical analysis and simulation results demonstrate that this gap adjustment strategy can effectively regulate the brake gap, mitigate the adverse effects of brake disk abrasion, and notably reduce the response time of the braking force output. Monitoring is critical to accurately control EMB clamping force. Pressure transducers are often expensive and have limited accuracy in high-temperature environments, so an estimate of the clamping force is required. In this research, the clamping force is estimated based on the identified contact points and the stiffness profile of the EMB. This method performs exceptionally well under low stiffness conditions and maintains a narrow error range even in high-stiffness scenarios.
Zhang, Yilong, Chen, Zixuan, Wu, Jinglai, Zhang, Yunqing
Safety Concepts for Future Electromechanical Brake Actuators15-17-03-00122/16/2024
A growing interest in electromechanical brakes (EMB) is discernible in the automotive industry finding its climax in an announcement of EMB series production in late 2022 [1]. The introduction of EMB allows for new design opportunities using distributed software on smart actuators. However, additional efforts are needed to ensure continuously high levels of safety even when established design principles in the brake system are changed. This article discusses different safety concepts that could potentially be put in place in EMB actuators. Therefore, safety goals that need to be satisfied by an actuator are derived. Furthermore, three different degrees of complexity are differentiated, evolving to different required electronic control units (ECU) and architectures. Additionally, also the safety of the actuation unit (AU) is considered to realize a holistic safety concept for the actuator. Finally, a conclusion is drawn comparing the different investigated concepts.
Schrade, Simon, Röhler, Andreas, Nowak, Xi, Verhagen, Armin, Schramm, Dieter
A Renewed Look at Centralized vs. Decentralized Actuation for Braking Systems2023-01-186511/5/2023
De-centralized brake actuation – that is, brake systems that incorporate individual actuators at each wheel brake location to both provide the apply energy and the modulation of braking force – is not a new area of study. Typically realized in the form of electro-mechanical brake calipers or drum brakes, or as “single corner” hydraulic actuators, de-centralized actuation in braking systems has already been deployed in production on General Motor EV1 Electric Vehicle (1997) in the form of electric drum brakes and has been studied continually by the automotive industry since then. It is frequently confused with “brake by wire,” and indeed practical implementations of de-centralized actuation are a form of brake by wire technology. However, with millions of vehicles on the road already with “brake by wire” systems - the vast majority of which have centralized brake actuation – the future of “brake by wire” is arguable settled. The question of what is next for braking technology is centered more on study of de-centralized actuation. There is little debate, especially with modern electronics and computing power, on whether de-centralized brake actuation technology can work – the technical feasibility has been largely proven. The frontier of study of this technology is instead “does it make sense,” in other words do the benefits outweigh the initial investments and the risks for high volume production. This question cannot be answered from purely within the confines of the braking system itself, as it has far ranged implications on everything from manufacturing to interior layout, to energy efficiency, and it affects other major systems such as propulsion and electrical. The present work takes a holistic look at the implications, both positive and negative, for brake systems with de-centralized actuation, and make a case for why the time may finally be here for broader implementation.
Antanaitis, David
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
Electro-Hydraulic Composite Braking Control Optimization for Front-Wheel-Driven Electric Vehicles Equipped with Integrated Electro-Hydraulic Braking System2023-01-186411/5/2023
With the development of brake-by-wire technology, electro-hydraulic composite braking technology came into being. This technology distributes the total braking force demand into motor regenerative braking force and hydraulic braking force, and can achieve a high energy recovery rate. The existing composite braking control belongs to single-channel control, i.e., the four wheel braking pressures are always the same, so the hydraulic braking force distribution relationship of the front and rear wheels does not change. For single-axle-driven electric vehicles, the additional regenerative braking force on the driven wheels will destroy the original braking force distribution relationship, resulting in reduced braking efficiency of the driven wheels, which are much easier to lock under poor road adhesion conditions. The integrated Electro-Hydraulic Braking system (iEHB) is the current advanced brake-by-wire system, which can build brake hydraulic pressure by its motor, and independently adjusts the four wheel braking pressures through the solenoid valves. Based on the characteristics of the iEHB, a composite braking control strategy for front-wheel-driven electric vehicles is proposed, which adjusts the braking force distribution relationship dynamically. Firstly, the structure of the iEHB system and the wheel braking pressure control principle are analyzed. Secondly, a composite braking control strategy that adjusts the braking force distribution relationship based on current regenerative braking force and wheel braking pressures is designed. Finally, simulations are carried out with the proposed control strategy and the single-channel composite braking control strategy. The simulation results show that the proposed composite braking control strategy can improve the braking efficiency of the driven wheels and improve the energy recovery rate.
Zhao, Xinyu, Xiong, Lu, Zhuo, Guirong, Shu, Qiang, Zhao, Xuanbai
Brake-by-Wire System Redundancy Concept for the Double Point of Failure Scenario10-07-03-00216/22/2023
Brake-by-wire (BbW) systems are one key technology in modern vehicles. Due to their great potential in the areas of energy efficiency and automated driving, they receive more and more attention nowadays. However, increased complexity and reliance on electric and electrical components in BbW systems bring about new challenges. This applies in particular to the fault tolerance of the brake system. Since drivers cannot form a fallback layer of braking functions due to the mechanical decoupling of the brake pedal, known BbW concepts provide a redundant system layer. However, driving is significantly limited in the event of a failure in the BbW system and is only possible under certain restrictions. The reason for that is a further possible failure (double point of failure scenario), which can result in a significant loss of braking performance. To improve the availability level of the braking functions, a principally new redundancy concept for the double point of failure scenario is presented. This allows for a less restricted driving operation when the BbW system is subject to failures. For this purpose, a central electric motor (CEM) and modified electronic parking brake (EPB) actuators are used on the front axle of a vehicle to form a separate redundancy layer. Strategies for deceleration and wheel slip control are developed for the individual actuators as well as for their simultaneous operation. The performance of the different brake modes is evaluated in road tests. The analysis shows that especially the combined operating mode of the CEM and EPB leads to high deceleration levels and robust operation in low road friction conditions.
Schlimme, Hauke Christian, Henze, Roman
Dodge is ready to sting the compact-SUV market23AUTD05_145/1/2023
If you accept that the oddball and odd-sized Journey never was a legit rival for the likes of the Honda CR-V, Toyota RAV4 and Ford Escape - and it wasn't - Stellantis' Dodge brand hasn't played in the compact SUV segment, one of the largest and most competitive in the U.S. That strategic gap is set to be filled by the 2023 Hornet, Dodge's performance-slanted attempt to peel out some sales volume from among the C-segment utilities that are typified by mundane and softly-tuned top-sellers. The Hornet's not just about having a little more engine power, either. Its platform is shared with the Alfa Romeo Tonale. Like Hornet, the Tonale slated to be in showrooms sometime in spring 2023 and incorporates chassis finery such as standard Koni-supplied Frequency Selective Damping (FSD) dampers. Specifically tuned, genuine by-wire braking (for the R/T trim) reduces curb weight by 9 lb. (4 kg) and improves steering feel via direct-action ratios from the electronic power steering; Stellantis claimed the Hornet GT's ratio, at 13.6:1 (shared with the Tonale) is the most direct in the segment.
Visnic, Bill
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
Panel Discussion: Advanced Brake Engineering for Future Vehicle Architectures1335310/13/2022
This panel will address two topics of interest related to the design, development, supplier-OEM relationship and customer experience for braking systems; the issues and challenges to implement braking systems in autonomous vehicles and the future implementation of dry brake by wire brake systems will be discussed. Experts from two major OEMs, two Tier 1 suppliers and from a Systems Engineering Integrator will bring their perspectives and input on these topics. Although either topic could be a conference in itself, the primary issues and challenges facing the industry as these technology areas approach reality will be addressed. Moderator: Jay Fash, Zoox Panelists: Robert Hill, Mando America Corporation John Pennala, General Motors LLC Beniamin Szewczyk, Brembo Spa Bernat Ferrer, Applus Idiada USA Hal Felch, Ford Motor Company
Schandelmeier, Brandie
Research on Brake Comfort Based on Brake-by-Wire System Control2022-01-09123/29/2022
The vehicle will produce certain shock and vibration during the braking process, which will affect the driving experience of the driver. Aiming at the problems of pitch vibration, longitudinal vibration and shock during the braking process, this paper proposes a planning and following control method for target longitudinal acceleration in post-braking phase, and designs control trigger strategies. Target longitudinal acceleration planning takes minimizing longitudinal shock as the design goal. The following control takes the brake pressure as the control object, and adopts the “feedforward +PID feedback” method to follow the target longitudinal acceleration. Besides, considering the safety of braking process, the trigger condition of control is designed which utilizes BP neural network method to judge whether the control has to be triggered. Based on Simulink software, the simulation model of straight-line braking is established. The results of straight-line braking simulation show that the proposed longitudinal acceleration planning and following control method can effectively reduce the pitch vibration amplitude, longitudinal vibration amplitude and longitudinal shock of the vehicle body. Also, the straight-line braking test of the vehicle was carried out, the test result shows that, based on meeting the braking safety requirements, the longitudinal acceleration planning and following control method can effectively improve the problem of pitch vibration, longitudinal vibration and shock.
Xiong, Wei, Wang, Weiwei, Jiang, Kaihong, Hou, Liming, Shangguan, Wen-Bin
Design and Hardware in the Loop Testing of AEB Controllers2022-01-00993/29/2022
Current ADAS systems can improve vehicle safety directly influencing its dynamics, reducing the impact of human error while driving. These functionalities have a high impact on the complexity of each unit installed on the car, potentially increasing the development time. In this work, a Hardware in the Loop testing bench and methodology for Autonomous Emergency Braking system is presented, aiming to enable a faster system development process. A commercial production brake by wire unit has been installed on a real-time driving simulator. The AEB functionality of the unit is activable in real-time during the simulation, by the means of a customizable control strategy. Two different AEB controllers have been implemented: the first one reproduces the unit stock functionality, while the second computes the requested deceleration using a PID control strategy. The two controllers have been tested in standardized EuroNCAP Car-to-Car Rear (CCR) collision scenario, implemented on the static simulator. The performances are then compared in terms of time to collision threshold necessary to avoid the impact, deceleration request and jerk, and vehicle-obstacle distance. The proposed methodology highlights the role of the static simulator as a development tool, allowing complete and immersive testing of both hardware and control strategies, greatly reducing the development time.
Alfatti, Federico, Garinei, Michele, Annicchiarico, Claudio, Capitani, Renzo
Hardware-in-the-loop testing of a hybrid Brake-by-wire system for electric vehicleSAE-PP-002403/1/2022
Recent trends in automotive engineering, such as electrification and automation, are opening chances as well as challenges due to the need of new chassis components (e.g., drivetrain, brakes, steering, suspension etc.) and control methods. Mechatronic components, so called X-by-wire systems, seem to become game-changers since they allow more efficient vehicle control with a higher operational speed for improving active safety, efficiency and driving comfort. Especially brake-by-wire (BBW) applications step into foreground, since they affect the bespoken aspects but have a limited use on serial vehicles yet due to the current maturity and the high impact of the systems on vehicle architecture. On the other hand, those systems have many advantages e.g., adjustable pedal feel, continuous wheel slip control and more effective recuperation of brake energy. Electromechanical brakes (EMBs) do not need brake fluid which make them easier to integrate (no pipes, no bleeding) and increase environmental friendliness. However, fully EMBs have also stronger functional safety requirements (e.g., redundant system design) that should be considered already on early development stages. Due to high demand for fast and cost-efficient development of BBW systems and functions especially for electric vehicles, the conflict between available testing capacities and design time restrictions is still challenging. One of the reasonable solutions can be the use of the X-in-the-loop validation and testing approach. This methodology deals with the tests of hard- and software at different stages of development process. The present paper deals with the case study on anti-lock braking system (ABS) design via Hardware-in-the-loop (HIL) tests and Rapid Control Prototyping (RCP) techniques. The hybrid brake-by-wire system, used in this study, has electrohydraulic brakes (EHBs) on the front and electromechanical brakes on the rear axle. Aspects like brake system architecture, control design, HIL testing environment, validation studies and their analysis will be further discussed.
Heydrich, Marius, Ivanov, Valentin, Bertagna, Alessandro, Rossi, Alessadro, Mazzoni, Matteo, Büchner, Florian
Vehicle System Integration (Electric Parking Brake)2021-36-04142/10/2022
The initial step to implement the brake-by-wire on vehicles is to replace the conventional mechanical parking brake with an Electric Parking Brake (EPB). This paper aims to share the experience in integrating the EPB into the vehicle with respect to design and validation points of view. It starts by introducing the EPB in comparison with the conventional mechanical parking brake, showing two kinds of EPB: with a drum brake (EPB-Si, Simplex integrated) and with a caliper (EPB-Ci, Caliper integrated). In sequence, it explains the most important EPB functions. After a basic knowledge introduction, it describes the integration process, separating into 3 different levels: mechanical, electrical, and software, having a brief description that includes some lessons learned from each one. Two parts compose the EPB system: drum brake or caliper with Motor Gear Unit (MGU) and the software to control it, Parking Brake Controller (PBC) library, running into the Electronic Stability Control (ESC) software/module. The biggest content is at the software level, which has a specific standard, “VDA 305-100 Recommendation for Integration of Electric Parking Brakes Control into ESC Control Units”, that supports two different Original Equipment Supplier (OES) working in cooperation to develop the EPB system for the Original Equipment Manufacturer (OEM). This work uses the VDA 305-100 Recommendation content as a base to provide some description of the most important integration items. The content is also based on the Automotive SPICE and ISO 26262. To conclude, this material presents the integrated project team and cooperation between other teams (OEM, Brake Assy OES, and ESC OES) to reinforce the importance of the synergy between all parties to achieve the objectives and fulfill the requirements optimizing time and resources. Working together to perform all alignments and troubleshooting to solve integration issues in a short time.
Dias, Fábio Gaiotto, Minutti, Carlos José, Menezes, Fabricio Oliveira
Active Safety Control of X-by-Wire Electric Vehicles: A Survey10-06-02-00081/24/2022
This article presents a survey on active safety control of X-by-wire electric vehicles. The steer-by-wire (SBW) system, brake-by-wire (BBW) system, and electric drive system are three critical techniques for X-by-wire electric vehicles. As to the three systems, the structure comparison and performance analysis of existing products and prototypes are conducted. Then two kinds of X-by-wire chassis configuration, i.e., the centralized type and the distributed type, are introduced. For active safety control, various control models are summarized, including vehicle dynamics model, single-track model, path tracking model, and wheel dynamics model. Based on the proposed model, different active safety control algorithms are introduced involving longitudinal dynamics control, handling stability control, rollover prevention control, path tracking control, and active fault-tolerant control. In addition, some data-driven approaches for active safety control of X-by-wire electric vehicles are reviewed. Furthermore, a comparative analysis between the model-based approach and the data-driven approach for active safety control is conducted. Finally, some challenges and prospects for the active safety control of X-by-wire electric vehicles are discussed and given.
Peng, Hang, Chen, Xinbo
E-Mobility-Opportunities and Challenges of Integrated Corner Solutions2021-01-09844/6/2021
E-mobility is a game changer for the automotive domain. It promises significant reduction in terms of complexity and in terms of local emissions. With falling prices and recent technological advances, the second generation of electric vehicles (EVs) that is now in production makes electromobility an affordable and viable option for more and more transport mission (people, freight). Current e-vehicle platforms still present architectural similarities with respect to combustion engine vehicle (e.g., centralized motor). Target of the European project EVC1000 is to introduce corner solutions with in-wheel motors supported by electrified chassis components (brake-by-wire, active suspension) and advanced control strategies for full potential exploitation. Especially, it is expected that this solution will provide more architectural freedom toward “design-for-purpose” vehicles built for dedicated usage models, further providing higher performances. Target of this paper are (a) to introduce the EVC1000 project and results achieved so far; (b) with the example of two vehicle platforms (AUDI E-tron and JAC iEV7) to discuss platform migration opportunities and challenges related to corner solutions, and (c) to present preliminary results (simulation based) with respect to expected performance increase.
Armengaud, Eric, Eitzinger, Stefan, Pirker, Hannes, Buh, Joze, Gramstat, Sebastian, Heimann, Stefan, Chen, Chiara, Ivanov, Valentin, Heydrich, Marius, Sorniotti, Aldo, Gruber, Patrick, Tavernini, Davide
A Passenger Car Brake Pedal Feel Analysis Model Based on Integrated Brake by Wire System2021-01-09754/6/2021
The fully decoupled brake by wire system is a complex system consisting of mechanical components such as springs and rubber and hydraulic structural components coupled together. Compared to conventional braking systems, it is characterized by the full decoupling of the brake pedal from the brake wheel cylinders in normal braking mode, and the pressure fluctuations in the wheel cylinders do not affect the pedal feel. In order to predict brake pedal feel in a passenger car, a dynamic model was developed for both normal and backup braking modes, taking into account the variation of the volume modulus of the brake fluid and the frictional forces of the master cylinder pistons. The influence of different pedal input speeds on the pedal feel characteristic curve was analyzed using static vehicle tests and the related parameters of the braking system were identified in order to correct the design data. Subsequently, a dynamic test of the vehicle pedal feel was conducted to establish a quadratic graph of pedal stroke, pedal force, servo cylinder pressure and vehicle longitudinal deceleration. The accuracy of the dynamics model was verified using vehicle tests, and we believe that this new dynamics model of the decoupled brake system can accurately predict brake pedal feel and can be used for the design and optimization of the brake system.
Yin, Faguo, Wang, Minghui, Jiang, Yongfeng, Kang, Yingzi
Numerical Investigation of Solenoid Valve Flow Field in Decoupled Brake-by-Wire System2021-01-08064/6/2021
The decoupling brake-by-wire system controls the key components of the flow path and liquid flow of the whole brake system through the solenoid valve of the bottom control unit. The reference cross-sectional area value at the valve inlet is obtained by calculation, and the valve body structure model is established. The flow channel structure is extracted, and the porous media model is used to replace the fluid area of the filter screen at the entrance of the solenoid valve. The Fluent software is used to analyze the influence on the flow characteristics of the solenoid valve with or without a filter. The accuracy of the model is verified by the experimental results, which also show that the porous medium can effectively and accurately reflect the characteristics of the solenoid valve end filter. Based on the simulation model, the influences of parameters such as the diameter of the solenoid valve inlet, cone angle and spool stroke on the internal flow field characteristics of the solenoid valve are analyzed, and the methods to improve the internal flow field characteristics of the solenoid valve are put forward.
wan, liping, Wang, Minghui, Jiang, Yongfeng, Zhao, Xuezhi
Research on Compensation Redundancy Control for Basic Force Boosting Failure of Electro-Booster Brake System2020-01-02164/14/2020
As a new brake-by-wire solution, the electro-booster (Ebooster) brake system can work with the electronic stability program (ESP) equipped in the real vehicle to realize various excellent functions such as basic force boosting (BFB), active braking and energy recovery, which is promoting the development of smart vehicles. Among them, the BFB is the function of Ebooster's servo force to assist the driver's brake pedal force establishing high-intensity braking pressure. After the BFB function failure of the Ebooster, it was not possible to provide sufficient brake pressure for the driver's normal braking, and eventually led to traffic accidents. In this paper, a compensation redundancy control strategy based on ESP is proposed for the BFB failure of the self-designed Ebooster. Firstly, introduced the working principle of Ebooster and ESP, and a suitable pressure-building circuit was selected for the dual brake actuator system; Secondly, after the BFB failure of Ebooster, the rule-based strategy of braking awareness recognition was designed. Thirdly, a layered closed-loop compensation control strategy is designed based on the ESP to restore the pressure building capacity of the hydraulic system. Finally, based on dSPACE products, a hardware-in-the-loop (HiL) experimental bench with dual brake actuators including ESP and Ebooster was built for algorithm verification. The HiL experiment results show that after the BFB failure of Ebooster, the designed compensation redundancy control algorithm can restore the Pressure-Volume (P-V) characteristics of the brake system just like Ebooster's conventional BFB mode, and improve vehicle driving safety.
Zhao, Jian, Chen, Zhicheng, Zhu, Bing, Wu, Jian
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