An Uniformly Stable Observer for Tire Friction Estimation During Braking Process

<div class="htmlview paragraph">Various systems have been introduced recently in the automotive industry to improve the safety, ride and handling qualities of passenger vehicles, such as anti-lock braking system (ABS), active suspension system, four wheel steering system, traction control system, etc. Although each system has been shown to impose positive effects on the performance of a vehicle, the benefits of integrating various systems is yet to be determined.</div> <div class="htmlview paragraph">A feasibility study was conducted of a new non-linear control law for integration of anti-lock braking system and active suspension system. The control law is based on the use of a candidate Lyapunov function. Lyapunov stability theorem is applied to synthesize the control law and the adaptation law necessary to estimate the unknown parameters of the vehicle/road system. The proposed MIMO non-linear control strategy can maintain desired values of various variables while estimating the unknown parameters of the system. The desired values for various states are obtained by solving an optimal control problem for a simple vehicle model. Simulations of braking maneuvers were conducted using a non-linear vehicle model together with a non-linear tire model. The preliminary study indicates that the controller designed is capable of maintaining desired front and rear wheel longitudinal slip values as well as generating sufficient suspension forces to minimize sprung mass vibrations.</div>

This paper deals with the control of an Anti-lock Brake System (ABS) assisted with an active suspension. The main objective is to track the slip rate of a car and ensure a shorter distance in the braking process. For the ABS subsystem an integral nested sliding mode controller based on the block control principle is designed. On the other hand, for the active suspension subsystem a sliding mode controller based on regular form and linear geometric techniques is proposed. Both closed-loop subsystems are robust in presence of matched and unmatched perturbations. To show the performance of the proposed control strategy, a simulation study is carried on, where results show good behavior of the ABS with active suspension under variations in the road.

Wheel slip control is a critical aspect of vehicle safety systems, notably the antilock braking system (ABS). Designing a robust controller for the ABS faces the challenge of accommodating its strong nonlinear behavior across varying road conditions and parameters. To ensure optimal performance during braking and prevent skidding or lock-up, the ideal wheel slip value can be determined from the peak of the tire–road friction curve and maintained throughout the braking process. Among various control approaches, model predictive control (MPC) demonstrates superior performance and robustness. However, online MPC implementation encounters significant computational burdens and real-time limitations, particularly when dealing with larger problem sizes. To address these issues, this study introduces an offline robust model predictive control (RMPC) methodology. The proposed approach is based on the robust asymptotically stable invariant ellipsoid methodology, which employs linear matrix inequalities (LMIs) to calculate a collection of invariant state feedback laws associated with a sequence of nested invariant stable ellipsoids. Simulation results indicate a significant reduction in computational burden with the offline RMPC approach compared to online implementation, while effectively tracking the desired wheel slip reference values and system constraints. Moreover, the offline RMPC design aligns well with the online MPC design and verifies its effectiveness in practice.

The prevalence of microprocessor-based controllers in automotive systems has greatly increased the need for tools which can be used to validate and tune the control systems over their full range of operation. The objective of this paper is to develop a real time simulator for an anti-lock brake system (ABS) based on the methodology of hardware-in-the-loop simulation using a personal computer. By use of this simulator, the analysis of a commercial electronic control unit as well as the validation of the developed control logic for ABS was performed successfully. The idea of the simulator can be applied to the development of more advanced control systems, such as traction control system, vehicle dynamic control system and so forth.

Hierarchical [formula omitted] fuzzy-neural control of anti-lock braking system and active suspension in a vehicle

Road friction coefficient is a key factor for the stability control of the vehicle dynamics in the critical conditions. Obviously the vehicle dynamics stability control systems,including the anti-lock brake system(ABS),the traction control system(TCS),and the active yaw control(AYC) system,need the accurate tire and road friction information. However,the simplified method based on the linear tire and vehicle model could not obtain the accurate road friction coefficient for the complicated maneuver of the vehicle. Because the active braking control mode of AYC is different from that of ABS,the road friction coefficient cannot be estimated only with the dynamics states of the tire. With the related dynamics states measured by the sensors of AYC,a comprehensive strategy of the road friction estimation for the active yaw control is brought forward with the sensor fusion technique. Firstly,the variations of the dynamics characteristics of vehicle and tire,and the stability control mode in the steering process are considered,and then the proper road friction estimation methods are brought forward according to the vehicle maneuver process. In the steering maneuver without braking,the comprehensive road friction from the four wheels may be estimated based on the multi-sensor signal fusion method. The estimated values of the road friction reflect the road friction characteristic. When the active brake involved,the road friction coefficient of the braked wheel may be estimated based on the brake pressure and tire forces,the estimated values reflect the road friction between the braked wheel and the road. So the optimal control of the wheel slip rate may be obtained according to the road friction coefficient. The methods proposed in the paper are integrated into the real time controller of AYC,which is matched onto the test vehicle. The ground tests validate the accuracy of the proposed method under the complicated maneuver conditions.

Introduction (statement of the problem and relevance). In accordance to the current standards the requirements were assessed: for the braking process efficiency of M1vehicles category using an antilock braking system (ABS) and the combined possibility control of two actuators - electric machines installed in the vehicle driving wheels as well as the electro-hydraulic modulation pressure unit in the hydraulic circuit of the working brake cylinders.The purpose of the study was to evaluate the effectiveness of the newly developed ABS algorithm in accordance with current standards and additional requirements.Methodology and research methods. The braking process computer simulation of a M1 vehicle category equipped with four electric motors and an electro-hydraulic braking system was carried out. As a result of calculations, the obtained braking parameters were to be compared and evaluate according to the requirements of UN Regulation No. 13H, as well as evaluate the braking efficiency parameters.Scientific novelty and results. The effectiveness of the developed control algorithm for the ABS actuators (electro-hydraulic unit and electric machines in the drive wheels) has been proven in terms of meeting the requirements of UN Regulation No. 13H. Studies showed an efficiency improvement of the ABS operating due to the proposed algorithm, when compared to foreign-produced analogues.The practical significance of the work is the proof of the developed algorithm efficiency for M1 electric vehicles category.

One of the main threads of every living person traveling over a road vehicle is rapidly developing injuries. According to a research published in a well-known magazine, one person dies every four minutes in India as a result of a traffic accident. And one of the main causes of these collisions is speeding. Engineers develop ‘ABS’ to prevent accidents caused by brake failure and power loss (Anti-lock Braking System). Prevents the wheels from locking during the panic brake, preventing the wheels from sliding. Other anti-lock braking systems, such as the Traction Control System (TCS), Electronic Stability Control (ESC), and Electronic Brake Power Distribution System (EBFD) or (EBD), have subsequently been created to help reduce the problem. Skidding and a lack of control cause injuries in any stage of the track.

The anti-lock braking system (ABS) can improve the safety of the vehicle. As the ABS assisted device, electronic brake force distribution (EBD) can automatically regulate the braking force distribution among the wheels of the vehicle, so that the wheels can reach the start condition of ABS at the same time, which can make better performance on braking distance and braking stability. In this paper, a mathematical model of the EBD system is built and the control system based on fuzzy control is designed. The results of the simulation on straight road show that the EBD control system is effective in the braking force distribution control.

<div>In order to improve the safety and dynamic performance of electric vehicles equipped with four in-wheel electric motors, and prevent the wheels from locking or slipping when braking or accelerating, a new longitudinal control strategy which combines ASR traction and ABS braking control is proposed using an observation algorithm of effective radius for four wheel of electric vehicle. Using the electric motor torques as the unique actuator signal sources, this combined ASR/ABS can act as acceleration slip regulation (ASR) by preventing the wheels from slipping during acceleration and as an antilock braking system (ABS) by preventing the wheels from getting locked during braking. A variation of effective radius of the wheel’s tire can have an incidence on the longitudinal and lateral control. Moreover, the wheel effective radius observer based on high order sliding mode approach using the information of the electric motor torques and the angular velocities is used in the combined ASR/ABS systems. First, adjusting the motor torque and based on Fuzzy logic control, the acceleration slip regulation (ASR) is designed to maintain the wheel slip in the optimal range using the angular acceleration and slip rate. Second, for limiting the wheel slip by adjusting the motor torque the sliding mode control is used. Several Matlab/Simulink simulation tests will be carried out to validate the effectiveness of the proposed controller.</div>

Tire-road friction coefficient is an essential parameter in vehicle safety control systems. In particular, friction information is required by antilock braking systems (ABS) during deceleration and by traction control systems (TCS) during acceleration. The characteristic of the force acting on the tires has an extremum, which is dependent in the road condition. This paper develops a recursive least squares (RLS) based extremum seeking algorithm that estimates the optimum slip ratio on-line to produce maximum deceleration/acceleration. Results of simulation studies in both Matlab and CarSim environments are presented to illustrate the effectiveness of the developed algorithm and numerically compare with gradient based estimation.

<div class="section abstract"><div class="htmlview paragraph">Anti-lock Braking Systems (ABS) for motorcycles have already contributed significantly to the safety of powered two-wheelers (PTW) on public roads by improving bike stability and controllability in emergency braking situations.</div><div class="htmlview paragraph">In order to address further riding situations, another step forward has been achieved with Motorcycle Stability Control (MSC) system. By combining ABS, electronically combined braking system (eCBS), traction control and inertial sensors even in situations like braking and accelerating in corners the riders' safety can be improved. The MSC system controls the distribution of braking and traction forces using an algorithm that takes into account all available vehicle information from wheels, power train and vehicle attitude. With its ability to control fundamental vehicle dynamics, the MSC system will be a basis for further development and integration of comprehensive safety systems.</div><div class="htmlview paragraph">The contribution of ABS towards motorcycle safety has been confirmed by numerous international research studies, making it the safety technology with the highest possible benefit for motorcycles available today. Recent investigations by Bosch accident researchers show the contribution of the MSC system to further increase the safety benefit for motorcycle riders by extending the acceleration and braking control functions to cover more riding situations. The MSC systems could avoid more than every 3<sup>rd</sup> accident with casualties involving a motorcycle in Germany.</div><div class="htmlview paragraph">This paper focuses on these new motorcycle technologies developed with centralized system architecture and their safety benefits in preventing and mitigating motorcycle accidents with injuries and fatalities.</div></div>

The electric wheel is a power device which is used to directly drive the vehicle by installing a hub motor on the wheel rim. Distributed drive vehicles utilize the vehicle control unit (VCU) to precisely control the torque and speed of each electric wheel, enabling precise and complex vehicle dynamics control. Independently controlled electric wheels provide more observers and actuators for vehicle dynamics control, as well as higher difficulty and requirement for vehicle dynamics control algorithms, especially for multi-axle distributed drive vehicles. Aiming at distributed drive hybrid multi-axle heavy-duty truck, this paper proposes a dynamics control algorithm. The algorithm uses a hierarchical control structure, including longitudinal and lateral dynamics control strategies, as well as low-layer control functions such as traction control system (TCS), anti-lock braking system (ABS) and braking torque distribution, etc. On the MATLAB/Simulink software platform, the vehicle model was established and the simulation test of the dynamics control algorithm was carried out. The dynamics control algorithm of this paper was applied to an actual liquid hydrogen fuel cell heavy-duty truck of the Beijing Municipal Science and Technology Commission project. Simulation and road test results verified the feasibility, accuracy and real-time performance of the algorithm.

Around 1.3 million people die every year on the world's roads of which 285,200 are users of motorised two or three wheelers. In Indonesia, the number of traffic accidents has also increased by an average of 13% annually (2009-2013). This leads to socio-economic loss of approximately 255,864 million rupiah (Rp). The European Transport Safety Council (ETSC) analysis shows the risk of a motorcyclist (Powered Two Wheeler - PTW) being involved in a fatal accident is 20 times greater compared to a car driver travelling along the same route. This research reveals interesting facts about the Indonesian PTW accident situation through mapping the benefit of Anti-Lock Braking System (ABS) for PTWs from India to Indonesia - although there is no in-depth data available to carry out thorough accident research study. One estimation is that every fourth accident with injuries involving a motorcyclist on Indonesian road can be avoided by a PTW with ABS (assuming a 100% installation rate of such device). This result is in line with other international studies claiming the avoidance potential of PTW with ABS.

Significant advances have been made in recent years in chassis control technology. Various control systems have been developed with the aim of enhancing vehicle dynamic performance at the same time as safety and comfort. Such controls include antilock brake systems ( ABS s), electronic stability control ( ESC ), electric power steering ( EPS ), active suspension, and variable torque distribution four‐wheel drive ( 4WD ). In addition, precrash safety ( PCS ) systems and other controls are also being developed using technologies that detect and recognize the environment around the vehicle. Coordination and integration controls play an indispensable role among these systems. This chapter describes the key technologies and configurations of integrated control systems, in view of advances in chassis control devices and vehicle environment recognition technology, as well as trends in integrated vehicle control systems.