Electromechanical Brake Research Articles

Design of Feed-forward Controller with Stick-slip Friction Modeling in Electro-mechanical Brake System

Electro-Mechanical Brake ( EMB ) is expected to be one of the future brake system. Feedback controller with sensor measuring is commonly used for control of EMB. However, this controller has some issues like delayed response and extra cost about sensor installation. In this paper, Feed-forward controller in EMB is proposed for solving these problems of feedback control. Also, it is very necessary to describe dynamical phenomenon of friction in actual EMB system. The actual EMB system shows stick-slip friction of mechanical parts which is difficult to model and apply to design of controller. This research is focused on exquisitely describing this stick-slip friction. In order to do this, the experiment about EMB is proceeded in the open loop system with the motor current command and data from the experiment is used for identification of model parameters during stiction. Then, parameters during slip is estimated in the closed loop system. Finally, developed friction model of EMB is proposed and it is utilized for design of feed-forward controller. Matlab Simulink is used for design of EMB simulation model and EMB test bench is utilized for experiment. Performance of proposed control system is compared with that of feedback control system.

TWO DESIGNS OF THE ELECTROMECHANICAL BRAKE EMBEDDED INTO AN ASYNCHRONOUS MOTOR

The significance of the braking devices is increasing due to the intensification of manufacturing, increase in the moving masses, speeds of movement and frequency of braking. During a short time period the braking device needs to convert a significant amount of mechanical energy into heat energy and transfer it into the environment without compromising the operability of both devices and machines in general. For electric actuators braking a normally closed mechanical brake is frequently used. When disconnecting the motor from the network the brake friction surfaces are closed and prevent rotation, and when the motor is switched on, they are opens under the action of the electromagnet, electro-hydraulic pusher, special electric motor, mechanical or pneumatic device. In the case of joint implementation of the asynchronous motor and the mechanical brake, the drive of quick stop is more compact and convenient. Such devices are further called asynchronous motors with electromechanical braking systems henceforth. The large number of requirements as well as different conditions of operation cause a large variety of designs of such motors. One of the major shortcomings of the functioning of well-known design is the periodic wear of the friction linings and the need for frequent replacement of them. The solution to this problem is the use of asynchronous motor with recessed combo braking device. However, for some mechanisms that do not require a smooth stop of the motor shaft and that have a speed of rotation of the motor shaft less than 1500 rpm, more simple and cheap solution would be the use of an electromechanical braking device with an air gap compensation. Due to wear of the friction linings the air gap of the electromagnet increases. Due to the compensation of the air gap of the electromagnet these devices make it possible to rub the material of the friction lining longer. The current designs of the electromechanical braking device with compensation of the air gap are quite bulky and complicated to be manufactured. Therefore, the authors developed, experimentally investigated and implemented two new, simple and cheap designs of electromechanical braking device with compensation of the air gap.

Active Brake Judder Attenuation Using an Electromechanical Brake-by-Wire System

Brake judder is an undesirable phenomenon in passenger vehicles whereby disk thickness variations lead to brake torque variations (BTVs) during light braking events with a consequence of reduced braking performance and driver satisfaction. Most solutions involve passive approaches; however, in this study, a novel active brake judder attenuation strategy utilizing the capabilities of a prototype electromechanical brake (EMB) is proposed. Two attenuation algorithms with different sensor requirements are presented, where compensating clamp force commands are generated to cancel the judder causing BTV arises during light braking. The first approach is founded on the linear parameter-varying (LPV) control structure, which is designed using the output regulation theory and scheduled using wheel angular speed and acceleration. The second approach examines the adaptive feedforward compensation, where the compensator is scheduled using wheel angular position, speed, and acceleration. Experimental investigations showed favorable results for the LPV compensator, albeit with high sampling rate requirements. On the other hand, the adaptive compensator demonstrated lower sampling rate requirements with better BTV attenuation, but required wheel position measurements. These results highlight the applicability of EMB in judder reduction and the advantage of having wheel position measurements.

Research of Sensor Fault Detection and Diagnosis for EMB System Based on CSA-SVM Model

Electro Mechanical Brake (EMB) is a high efficiency pure electric vehicle braking system which is based on the technology of Electronic, machinery, communication network. Because of the expensive cost and immature key technology in safety and reliability, the products cannot be mass-produced on the market at present. Electronic control of the EMB system needs a variety of sensors information feedback, therefore, how to correctly detect and diagnose the faults of the sensors is one of the important problems for the development of pure electric vehicles. Based on three-loop control architecture model of EMB system, the sensor fault detection model is established on the basis of Support Vector Regression (SVR), and the sensor fault diagnosis model is established on the basis of Support Vector Classification (SVC). In order to further improve the Support Vector Machine (SVM) for fault classification accuracy and fault detection reliability, the parameters of SVM can be optimized by using Clonal Selection Algorithm (CSA) and the modified CSA-SVM model is established. Simulated result of experiment indicates that the proposed CSA - SVM fault detection rate is increased than the traditional SVM by 62.5% and the fault classification accuracy is increased by 10% which laids a solid foundation of fault-tolerant control technology for the EMB system.

Analytic approaches for keeping high braking efficiency and clamping efficiency of electro wedge brakes

The transfer from engine drive vehicles to electric vehicle has been proceeding due to fuel exhaustion, higher fuel costs, and environmental restrictions. This trend has also led to a transition in brake system from the hydraulic brake system to the electric brake system, which uses electric power. This electric brake system has led to an enhancement of safety and eco-friendliness due to a reduction braking distance, a rapid-response property, and the elimination of braking oil. However, one of the big problems to solve for practical usages is the need of a high power motor to enable braking forces as strong as those of hydraulic brake systems. Therefore, it is necessary to develop high efficiency electro mechanical brakes with a proper reinforcement mechanism to solve this problem. In this paper, we describe a wedge structure that has a self-reinforcing effect; we propose a proper actuating direction for a movable wedge to obtain greater clamping efficiency and braking efficiency, which will mean a better relation of the motor force as the input to the braking force as the output. Further, we propose the method to keep the most braking efficiency and clamping efficiency without reference to the variations of frictional coefficient.

Active Brake Judder Compensation Using an Electro-Hydraulic Brake System

Geometric imperfections on brake rotor surface are well-known for causing periodic variations in brake torque during braking. This leads to brake judder, where vibrations are felt in the brake pedal, vehicle floor and/or steering wheel. Existing solutions to address judder often involve multiple phases of component design, extensive testing and improvement of manufacturing procedures, leading to the increase in development cost. To address this issue, active brake torque variation (BTV) compensation has been proposed for an electromechanical brake (EMB). The proposed compensator takes advantage of the EMB's powerful actuator, reasonably rigid transmission unit and high bandwidth tracking performance in achieving judder reduction. In a similar vein, recent advancements in hydraulic system design and control have improved the performance of hydraulic brakes on a par with the EMB, therefore invoking the possibility of incorporating the BTV compensation feature of the EMB within hydraulic brake hardware. In this paper, the typical characteristics of electromechanical and electro-hydraulic brake systems are presented. Based on the experimental results, the feasibility of active BTV compensation on the electro-hydraulic brake (EHB) systems is discussed. Furthermore, a BTV compensation algorithm designed for the EMB is presented and is shown to be applicable to the EHB. Using an experimentally validated model of BTV, the compensation was performed on a hardware in-the-loop EHB test rig. The preliminary results demonstrate the potential of using an EHB to compensate for brake judder.

Research of Sensor Fault-Tolerant Control Based on CSA-SVR Algorithm for EMB Actuator System

The electro mechanical brake (EMB) system is a efficient pure electric vehicle braking system in where technologies in the fields of electronics, mechanics, and vehicle communication network were considered at the same time. Because that offered information to the electronic control of the EMB system is taken from several detectors, during developments of the pure electric vehicle, unsolved difficulties in EMB system are the accurate fault detection as well as the timely process of a fault tolerant control. In this paper, the fault detection and the fault tolerant control on the mathematical models of a current, a speed, and a pressure detector loaded on the EMB actuator system will be studied. Based on the three-loop control architecture model of the EMB actuator, these models of detectors are constructed by the method of the dynamics analysis of the actuating agency respectively. On the purpose of improving the accuracy of fault detection, the clonal selection - support vector regression algorithm (CSA-SVR) is proposed, which is a combination of CSA and SVR calculation methods. Through CSA-SVR algorithm, optimized parameters of support vector machine (SVM) and improved accuracy of fault detection are obtained. The adaptive fault tolerant control architectural model mentioned which is designed using CSA-SVR algorithm in this paper shows effective function in fault detection, isolation from fault, and fault estimation.

Observer-Based Phase-Shift Fault Detection Using Adaptive Threshold for Rotor Position Sensor of Permanent-Magnet Synchronous Machine Drives in Electromechanical Brake

This paper designs an observer-based fault detection method with an adaptive threshold for a rotor-position-sensor fault of permanent-magnet synchronous motor drives in an electromechanical brake (EMB). The observer does not fully agree with the real process due to model uncertainties and parameter variations. To avoid missing or false alarms, a key design issue of the proposed detection method is the adaptive threshold, which is determined by analyzing position estimation errors of the observer. Experimental results using a test bench of an EMB show the effectiveness of the designed method.

Research on Electro-Mechanical Braking System Control of EV Based on Maximum Energy Recovery Strategy

With the analysis of influence factors on regenerative braking in electro-mechanical braking system, and considering the power battery charging characteristics, a regenerative braking system control strategy for electric vehicle is researched in this paper. The models of the motor and the whole vehicle are built in AMESim. The control effects and the braking force distribution on front and rear wheels of the control strategy in an FTP-72 driving cycle are simulated and analyzed. The simulation results show that the control strategy could be utilized in the 4WD electric vehicles. The ideal braking force distribution on front and rear wheels and the high amount of recovery energy could be achieved.

A Control Strategy of Regenerative Braking System with Motor ABS for In-Wheel-Motor Vehicle

The electro-mechanical braking system of In-Wheel-Motor vehicle is analyzed by applying vehicle braking stability theory. Considering the properties of composite lectro-mechanical braking system, a regenerative braking system control strategy with ABS function for In-Wheel-Motor vehicle is proposed. In the strategy, the ABS function is achieved by adjust the motor torque. With using the new strategy, simulations are conducted on an in-wheel-motor vehicle model, and the road adhesion coefficient in the simulation is 0.2 and 0.8 respectively. The result shows that the control strategy proposed enhances the braking stability of In-Wheel-Motor vehicle.

Stability Control of 4WD Electric Vehicle with In-Wheel Motors Based on Integrated Control of Electro-Mechanical Braking System

Each wheel torque can be controlled independently, so four-wheel-drive electric vehicle can not only control the vehicle stability through hydraulic braking pressure regulation, but also through controlling the motor driving and braking force to generate yaw moment, which are different with the conventional vehicles. 4WD Evs have potential applications in control engineering. Both in-wheel motors and the EHB are actuators for vehicle stability control. In this paper, a vehicle co-simulation platform is constructed through the application of AMEsim and Simulink, additionally, a fuzzy controller is designed to generate yaw moment so as to compensate for deviations between CG slip angles and yaw rate. The simulation results show that the stability control system with motors and a mechanical load brake system can effectively improve the handling stability of the vehicle.

Research of Multiple Sensors Adaptive Fault-Tolerant Control Based on T-S Fuzzy Model for EMB System

In the electro mechanical brake (EMB) system, an improvement of the fault-tolerant control, like invalid protections of sensors and electric systems are the key problems to the development of electric vehicles. The adaptive fault-tolerant control in this paper is focus on the descriptor nonlinear system which contains double time-delays and parameter uncertainties. In fault detection and estimation, construct the controlled system model which contains multi-sensor, double time-delays and parameter uncertainties based on T-S fuzzy model, then design the observer to realize fault detection and estimation in real-time. In building the fault-tolerant control model, the first step is to choose an appropriate sliding surface, and combine the algorithm of sliding control with adaptive generic model control. Then apply the state observer to the designed sliding adaptive generic model, and build the decision model with dynamic fault reconfiguration. And the goal of this paper about the adaptive robust fault-tolerant control for the complex nonlinear controller system is achieved. Numerical SIMULINK simulation examples are given to illustrate the application and the effectiveness of the proposed design method.

Design and Application of Electromechanical Brake System

Aim at the brake fluid system cannot protect the automobile security effectively, this article analyzes the electromechanical brake system in details. At first, it introduces the theory and the advantage composition of the electromechanical brake system. Then, this article introduces the hardware of EBS system and evaluates the design of EMB electrical machine and electron pedal. At last, it particularly analyzes the system software. This article has significant meaning to the automobile maintainers and the braking system researchers.

Variable Structure Control Strategy Research on Regenerative Braking for a Brushless DC Motor Driven Electric Bus Cruising Downhill

To use regenerative braking to act as an auxiliary brake to maintain the constant speed of a brushless DC motor driven electric bus (BDCMEB) on downhill based on the feature of double-loop control structure of the control method for electric vehicle traction motor and the variable structural characteristics of PWM Control System for brushless DC Motor. A double-manifold variable structure control method to control regenerative braking is proposed for the bus cruising downhill. The impact of lead-acid battery's charge acceptance ability over a long charging period on the regenerative braking force of a driving motor is analyzed. Dynamic model of the bus on long downhill is established. A double-manifold variable structure controller is designed for the DCMEB on long downhill. The simulation result shows that the control system maintains enough stability and strong robustness. It may be achieved for the bus to maintain a constant speed downhill only by regenerative braking on a smaller slope. But the dynamic process is very slow. When deceleration or a constant speed is desired on a larger slope, only by electro mechanical parallel braking can the bus track the target speed precisely and quickly.

Adaptive Control System of Transport Wheels Electromechanical Braking

The development of the controlled electromechanical braking devices for transport wheel is discussed. The generalized functional block diagram of an electromechanical braking device is described. The mathematical model describing dynamic behavior of the braking transport wheel with pneumatic tires and electromechanical engine is given in detail. On the basis of the developed mathematical model a system of direct adaptive control of the braking mode transport wheels is build. Control law at the same time suppresses the effect of elastic deformation. Some results of efficacy studies of adaptive control system constructed are also given.

Fault Detection and Estimation for Electromechanical Brake Systems Using Parity Space Approach

In future, existing hydraulic braking systems will be replaced by electronic braking systems called brake-by-wire (BBW). The BBW units such as electromechanical brake (EMB) are lighter than hydraulic brakes and relatively faster in response. However, the most important issue for adopting BBW units to vehicle is the reliability of their performance. Partial or complete failure of the BBW units can cause not only dangerous situations but also liability for damages. In this study, a sensor fault diagnosis method is proposed by combining parity space and observer design approaches for EMB sensors; current sensor and position (or speed) sensor. The residual generator is constructed to detect sensor faults and fault sizes are estimated using the generated residual information. The EMB model as well as the proposed fault detection and estimation methods is verified in the EMB hardware-in-the-loop simulation (HILS) test bench.

Research of Fault Detection and Diagnosis for EMB Sensors System Based on Particle Filter

The electro-mechanical-brake (EMB) system which influences safety and reliability of a pure electric vehicle has received much attention. In EMB system, the feedback sensor signals enhance the accuracy of a pure electric vehicle brake. According to EMB sensor faults, the EMB mathematical model is established based on brushless DC motor (BLDCM). It provides analytical signals for a motor current, a motor speed, and a braking force to an EMB controller. Considering nonlinear characteristics of the EMB system, an observer is designed based on particle filter (PF) algorithm. Then, a sensor state and a fault can be directly estimated by this observer. Also, the residual is used for the sensor faults detection. The simulation result shows that when a sensor has a fault, the designed particle filter not only detects the fault in real-time, but also can locate the fault sensor accurately. The proposed method is proofed feasible and effective.

Study of Mechanism for Wear Adjustment with Electro Wedge Brake

Electro wedge brake (EWB) have been suggested and improved for enhancing the braking efficiency and reducing the weight and power of actuating motor than electro mechanical brake (EMB). This is due to self-reinforcement features of the wedge mechanism. On the other hand, the conventional hydraulic brake system has the passive wear adjustment without any sensors and actuators. This is because of the sealing rubber which is disposed between the hydraulic cylinder and piston, and supply the piston’s same restoring strokes regardless of pad’s wear amounts. This feature leads to the uniform distance between the disc and the pad. In comparison, electronic brake systems such as EMB and EWB don’t have the hydraulic piston and cylinder with the sealing rubber. Therefore the electronic brake systems cannot use the function of this passive wear adjustment. However, if the electronic brake system has gap sensors for detecting distances between the pad and the disc, and actuators for keeping the uniform distances between the pad and the disc, then the brake system can have the function of wear adjustments. One of our research goals is the embodiment of cost-effective and feasible wear adjustment mechanism which is proper to EWB. In this paper, as a chain of EWB’s development, we describe the proposed mechanism for wear adjustment with EWB. Further we describe the feasibility of this mechanism with the simulation study.

Approach to functional safety-compliant ECU design for electro-mechanical brake systems

In this paper, we propose a design approach to a functional safety-compliant ECU for an electro-mechanical brake (EMB) control system or an electronic wedge brake (EWB) control system. Brake actuators in a brake-by-wire (BBW) system such as EMB or EWB are characterized by the safety-critical functions which are now executed by using many electric and electronic devices with application software. Based on hazard analysis and risk assessments of the automotive functional safety standard ISO 26262, the proposed EMB control system should be ASIL-D-compliant, which is the highest ASIL level. To this end, a hardware and a software design method is introduced to implement functionl safety-oriented monitoring functions which are based on an asymmetric dual-core architecture with an external watchdog processor. It is shown by using EMB hardware-In-the-Loop-Simulation (HILS) that the proposed ECU design approach is very effective when a hardware fault or software execution faults occur in the EMB ECU, moreover, this functional safety-compliant design can be well combiled with the sensor fault-tolerant control logic.

Performance of an Electro-Mechanical Parking Brake (EMPB) System

A mechanical parking brake is one of the most important safety subsystems in a vehicle. Its main function is to hold a vehicle in position when parks on a flat or slope road. A typical problem of the mechanical parking brake system is that it requires a driver to apply sufficient or sometimes high pulling force to keep the vehicle stationary at any road slopes. Insufficient pulling force may cause the vehicle to move away or known as rollaway phenomenon. In order to overcome such an issue, an electro-mechanical parking brake (EMPB) is proposed and developed. The EMPB system is then tested using in-house parking brake test bench. It is found that the EMPB takes within 0.6s to fully engage and within 0.5s to disengage the system, respectively at 11.3 degrees of the road slope. Thus, current design of an EMPB system can prevent rollaway problem and also can be used as alternative replacement for the existing fully mechanical parking brake system.