A New Sliding Mode Controller for Four-Wheel Anti-Lock Braking System (ABS)

Braking system plays a major safety feature in any vehicle; it is considered as one of the key points in safe motoring. The main objective of a good braking system is to provide safe stopping, in addition to the fact that it provides repeatable stopping. Anti-lock Braking System (ABS) is one of the recently developed safety feature used in a vehicle in order to prevent wheels from locking. This article proposes an intelligent adaptive fuzzy logic (FL) genetic algorithm (GA) controller for the Anti-Lock Braking System (ABS) to control the braking of a vehicle by controlling the slip ratio based on quarter car model. The main objective of the proposed controller is to prevent wheels from locking, which is a major safety issue in any braking system for different road conditions. The proposed controller consists of a Fuzzy Logic (FL) Genetic Algorithm (GA) based controller. The Genetic Algorithm is utilized in tuning the membership functions of the Fuzzy logic controller, which is developed to calculate the amount of reduction of the applied torque due to applying brake based on the error of the measured slip ratio signal compared with the desired one. Then a Genetic Algorithm (GA) is utilized in tuning the Fuzzy Logic parameters, which are the center of the Gaussian membership function, and the spread (б). The simulation results of the proposed fuzzy logic genetic algorithm controller are compared with both the results of the Fuzzy logic controller and the PD controller developed in previous work of the authors. The simulation results present many advantages of using Fuzzy Logic Genetic Algorithm based controller over both the Fuzzy Logic and the PD controllers, and the simulation is carried out at different road conditions, namely dry, wet and icy road surface.

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

<div>As the basic function of the active safety configuration of a vehicle, the anti-lock braking system will compromise the driving safety if it fails. Based on the self-designed electro-hydraulic braking system, this article proposes an anti-lock brake redundant control architecture. The electro-hydraulic braking system is mainly composed of four parts: a brake pedal unit, a hydraulic drive unit, a brake execution unit, and a control unit. The mechanical structure is compact and exquisite, and the system has the function of precise and adjustable hydraulic pressure. The control architecture adopts a hierarchical control design, which is mainly composed of an upper wheel slip rate controller and a lower hydraulic pressure controller. Both the upper and lower controllers use a sliding mode variable structure control to improve the robustness and accuracy of the control. The upper slip rate controller outputs the desired master cylinder hydraulic pressure with the optimum slip rate of the rear wheels of the vehicle as the control target. The lower hydraulic pressure controller outputs the desired torque of the motor with the desired master cylinder hydraulic pressure as the target and achieves hydraulic pressure regulation of the master cylinder by controlling the motor motion. To verify the effectiveness of the algorithm, co-simulation and a hardware-in-the-loop test platform are built. Anti-lock braking tests are carried out under different typical working conditions: low-adhesion road, high-adhesion road, butt road, and split road. The results show that when the anti-lock braking system fails, the redundant control algorithm can achieve effective slip rate control under different driving road conditions and meets the anti-lock brake redundant control requirements. This study provides a reference for the development of low-cost anti-lock braking redundancy functions for vehicles equipped with electro-hydraulic braking systems.</div>

This paper presents the development of a PID controller for an Antilock Braking System (ABS) using vehicle longitudinal model. A Five Degree of Freedom (5-DOF) vehicle longitudinal dynamic model was derived and integrated with an analytical tyre dynamics, the Magic Tyre model. Several transient handling tests are performed such as sudden acceleration and sudden braking test to validate the vehicle model. The model is used as a plant to develop an antilock braking system to control longitudinal slip and reduce the stopping distance. A hydraulic brake model was developed as the brake actuator to produce brake torque. A conventional PID controller has been implemented to deal with the strong nonlinearity in the design of ABS controller. The proposed ABS control structure is shown able to significantly reduce stopping distance and control the longitudinal slip during heavy braking.

<div class="section abstract"><div class="htmlview paragraph">Anti-lock Braking System (ABS) is a critical safety component and its performance is crucial for every vehicle manufacturer. The tire plays an important role during an ABS braking maneuver as it is the component that connects the vehicle to the ground and is responsible for generating braking force. The steady-state and transient properties of the tire affect the operation of the vehicle's ABS system and consequently affects its performance/ operational efficiency. The main objective of this study is to investigate how tire design changes influence its interaction with the ABS and its eventual effect on stopping distance. This was conducted through an experimental study where tires were built with three levels of variation in carcass stiffness, tread stiffness and tread compound. Following this, ABS braking maneuvers were performed on two instrumented vehicles including a mid-tier sedan and a high-performance sports car. The steady-state properties of the tire were calculated from experimental data measured both on the vehicle and from the braking skid trailer and thereafter the sensitivity of a given ABS system to such changes in tire properties were analyzed. Lastly, the feasibility of adding intelligence in ABS controllers is investigated through an on-line tire identification routine to determine the tire slip set point value for the ABS controller to maximize the tire braking force.</div></div>

Anti-lock and also Anti-slip braking system controller designed for stability enhancement of vehicle during braking and turning circumstances is presented. Using available signals, a novel structure is proposed for vehicle stability improvement encountering critical braking conditions such as braking on slippery or μ-split road surfaces. In conventional vehicles, undesired lane changes may occur due to equal dispatch of braking torques to all wheels simultaneously. Also, intensive pressure on brake pedal can bring about wheels lockup which results in vehicle instability and undesired lane changes. The Anti-Lock Braking System (ALBS) and also Anti-Slip Braking System (ASBS) can serve as a driver assist system in vehicle path correction facing critical driving conditions during braking and turning round on different road surfaces. For these purposes, at first, a reference yaw angle is used for predicting of stable vehicle path. Then, slip of each wheel will be controlled by an Anti-Slip fuzzy controller which has been designed for each wheel. Also, a sliding mode controller has been designed so as to control the yaw angle concerning the yaw error where the yaw error is resulted from the difference between the reference value and actual yaw angle. Then, the difference between the left and the right wheels braking torques is used by the sliding mode controller in order to decrease the yaw error. Considering a model of Three-Degree-of-Freedom for chassis modeling and One-Degree-of-Freedom Dugoff's tire model for each wheel, a series of Matlab/Simulink simulation results will be presented in order to validate the effectiveness of the proposed controller.

<div class="section abstract"><div class="htmlview paragraph">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.</div></div>

<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>

<div class="htmlview paragraph">Most vehicles built today are fitted with anti-lock braking systems (ABS). Accurate simulation modeling of these vehicles during braking as well as combined braking and steering maneuvers thus requires the effects of the ABS to be included. Simplified, lump parameter models are not adequate for detailed, 3-dimensional vehicle simulations that include wheel spin dynamics. This is especially true for simulating complex crash avoidance maneuvers. This paper describes a new ABS model included in the HVE simulation environment. It is a general purpose model and is available for use by any HVE-compatible vehicle simulation model. The basic operational and control characteristics for a typical ABS system are first reviewed. Then, the specific ABS model and its options as implemented in the HVE simulation environment and employed by the SIMON vehicle simulation model are described. To validate the model, pressure cycles produced by the model are compared with stated engineering requirements. In addition, pressure vs. time histories for two ABS simulations on surfaces with different frictional characteristics are compared with experimental data. Finally, the gross effects of ABS on two simulated maneuvers (straight-line braking and ISO 3888 lane-change maneuver) are presented.</div>

Independently developing anti-lock braking system(ABS) is the basis of mastering the active dynamic control technology of vehicle chassis.According to the experimental data and the logic threshold control method widely used in the industrial ABS,the impact on ABS control of every logic threshold is analyzed and the basic rules of calibrating the logic thresholds is established.By borrowing the idea from the self-tuning regulator in adaptive control,a logic threshold self-adjusting algorithm is presented.The algorithm identifies the optimal brake slip ratio of the road and calculates the reference speed on-line.The main logic thresholds are adjusted automatically according to the error between the wheel slip ratio and the optimal slip ratio in order to improve the control performance.The control parameters are calibrated and the control performance of the self-adjusting algorithm is verified by road tests under various conditions.The test results indicate that the presented logic threshold self-adjusting algorithm overcomes the influence of different factors,such as road adhesion coefficient,speed and load,on the ABS,thereby the optimal ABS control under every condition is realized.The developed ABS has good control effect and meets the development requirement.It provides a foundation for ABS industrialization.

<div class="section abstract"><div class="htmlview paragraph">The National Highway Traffic Safety Administration (NHTSA) has developed its Light Vehicle Antilock Brake Systems (ABS) Research Program in an effort to determine the cause (s) of the apparent increase in fatal single-vehicle run-off-road crashes as vehicles undergo a transition from conventional brakes to ABS. As part of this program, NHTSA conducted research examining driver crash avoidance behavior and the effects of ABS on drivers’ ability to avoid a collision in a crash-imminent situation. The study described here was conducted on the Iowa Driving Simulator and examined the effects of ABS versus conventional brakes, speed limit, ABS instruction, and time-to-intersection (TTI) on driver behavior and crash avoidance performance. This study found that average, alert drivers do tend to brake and steer in realistic crash avoidance situations and that excessive steering can occur. However, this behavior did not result in a significant number of road departures.</div></div>

<div class="htmlview paragraph">Basic requirements for a motorcycle brake system include achieving adequate deceleration and improving motorcycle stability during braking by easy operation. To help realize these requirements, Combined Brake System (CBS) and Antilock Brake System (ABS) for motorcycle have been researched and developed.</div> <div class="htmlview paragraph">A new brake system which combines CBS with ABS has been recently researched and installed on a test motorcycle. The results of braking tests showed high performance in deceleration and good braking feeling especially during ABS actuation.</div>

With the development of the global automotive industry, environmental pollution and driving safety have been major problems. This paper focuses on a novel integrated cooperative antilock braking system (ABS) controller, which is used for antilock regenerative braking systems (ARBS) and antilock mechanical braking systems (AMBS) for hybrid electric vehicles (HEV) driving on different road surfaces. An intelligent tire system is utilized to detect varying road surfaces to obtain friction information and optimal operation slip ratio. In addition, the HEV eight‐degree‐of‐freedom dynamics model is developed for ABS control, which includes the LuGre tire model. Adaptive backstepping and finite state machine controllers are explored to maintain optimal wheel slip and regenerate energy, based on wheel slip, battery state of charge (SOC), motor capability torque, and vehicle velocity, and to develop the switching rules of regenerative and mechanical braking systems. In order to evaluate the performance of regenerative and mechanical braking systems on harvesting energy and driving safety, the HEV and LuGre dynamic tire models are developed in MATLAB SIMULINK /SimDriveline. The estimation results of different road surfaces and slip controller effects are tested via the experiments and simulations, finding good braking performances and high regenerative efficiency in different maneuvers.

<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>

Electric vehicles (EVs) have the advantage of using both regenerative braking and mechanical braking to produce the necessary braking torque. Currently, vehicles use Anti-lock Braking Systems (ABS) which provide intermittent braking torque to the vehicle and thereby prevents skidding or slipping of the vehicle by ensuring pure rolling of the wheels. Regenerative braking on the other hand generates the necessary braking torque by converting the kinetic energy of the vehicle to electrical energy via the motor(s). To coordinate both braking systems, the conventional method involves the use of crisp logic controllers that depend on lookup tables containing the data about various aspects of the vehicle such as battery state of charge (SoC), brake pedal input etc., to enable co-operative control of both systems. This paper presents a combined implementation of both braking systems in electric vehicles using separate fuzzy controllers for both ABS and regenerative braking. The control scheme is implemented such that when regenerative braking is not capable of providing enough braking torque, braking will be one by ABS. Two fuzzy logic controllers have been used, one to implement regenerative braking and the other to implement mechanical braking via ABS. If such a control algorithm is used, the driver will not have to manually adjust the level of regenerative braking in the vehicle and such an approach ensures that the braking process of an EV is smooth, safe and efficient. It also reduces the wear and tear of the brake pads thereby extending their life and reducing the cost of maintenance and by extension the total cost of ownership of the vehicle. The results demonstrate that the controllers for both ABS and regenerative braking can coordinate efficiently and reliably to produce proper and safe braking of the vehicle.