In order to improve the braking performance of electric vehicles, a novel brake-by-wire actuator based on an electro-magnetic linear motor was designed and manufactured. For the purpose of braking force regulation accuracy and high robust performance, the state observer and the anti-disturbance controller were designed in this paper after describing the actuator structure, braking principle, and mathematical model. The simulation and experimental results showed that the brake actuator responded rapidly, since its response time was only 15 ms. Compared to traditional PID (Proportion Integration Differentiation) methods, the controller proposed in this paper is able to regulate the braking force more precisely and has better anti-disturbance performance, thus the braking process can be accurately controlled according to the driver’s demand. The vehicle simulation results showed that the braking distance and braking time were shortened by 12.19% and 15.54%, respectively compared with those of the conventional anti-lock brake system (ABS) in the same braking conditions.

This paper reviews and summarizes the development, key technologies, and application of brake-by-wire (BBW) actuators. BBW is the technology orientation of future vehicle brake system. The main feature of BBW is to replace some of the mechanical and hydraulic components of traditional brake system with electronic control components, and use cables and wires to transmit energy and signals. BBW actuators have outstanding advantages, such as fast response, accurate control, and compact structure. They are easy to integrate with active safety functions and they are easily matched with the regenerative braking systems of electric vehicle. First, this paper summarizes the classification, characteristics, performance, and architecture of BBW actuators. Subsequently, the braking process regulation of vehicle is considered to be the main target, which is summarized from two aspects of actuator regulation and braking force distribution. The state estimation algorithm and control algorithm applied to these actuators are summarized and analyzed, and the development trend, challenges, and schemes of the braking force distribution are proposed. The development and research trend of braking force match strategies between the regenerative brake system and BBW system are also analyzed and summarized. The further electrification and intelligence of vehicle demand BBW's braking force control method and distribution method must have higher control accuracy, stronger robustness, and wider adaptability, and the effects on braking comfort and handling stability must be further discussed.Actuators 2020, 9, 15 2 of 24 new features [2,3]. The additional functions, such as ABS and ESP, require additional devices, such as high-speed solenoid valves, oil return pumps, and return lines. Therefore, the structure of hydraulic brake system is becoming increasingly complex, and the maintenance is also becoming more and more difficult [4,5]. At present, new energy vehicles, such as electric vehicles (EV), hybrid electric vehicles (HEV), and fuel cell electric vehicles (FCEV), are developing rapidly and are highly concerned by major automotive manufacturers. However, most electric vehicles still use hydraulic brake system. On the one hand, the electric vehicles cannot use vacuum boosters to provide auxiliary force. The electric hydraulic pump must first be used to increase the hydraulic pressure, and then delivers the high pressure to each wheel. The electric energy needs to be converted and then transmitted multiple times in this process, so the energy utilization efficiency is not high, and there is the potential danger of brake fluid leakage. On the other hand, the hydraulic brake system cannot accurately and independently regulate the braking force, so it cannot be well matched with the regenerative brake system of EV and HEV [6].Actuators 2020, 9, 15 2 of 24 hydraulic brake system is becoming increasingly complex, and the maintenance is also becoming more and more difficult [4,5]. At present, new energy vehicles, such as electric vehicles (EV)...

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The brake-by-wire actuator was considered to be the next generation of vehicle brake, which uses cables to transmit signals and energy, and uses electric motor instead of hydraulic element or pneumatic element. This paper designs a new type of brake-by-wire actuator based on the special linear motor. First, the structure, composition and working principle of the linear motor are explained. Secondly, the caliper structure and amplification mechanism of the actuator are designed. Thirdly, the controller and control strategy based on dSPACE platform are introduced in detail. Finally, the electromechanical parameters of actuator were identified, and the experiment of the linear motor and brake-by-wire actuator were completed. The experiment results show that the new actuator has the advantages of fast braking response, low control difficulty and high control accuracy, etc. In conclusion, this paper provides a new design scheme for the brake-by-wire actuator, and has the potential to further research and replace the traditional hydraulic braking system.

For the characteristics of full electric propulsion, a novel kind of brake-by-wire unit is designed for electric vehicle to improve braking performance. A comprehensive brake-by-wire system including this unit is set up after its structure and principle are introduced. Then, a multi-layer fuzzy controller is proposed to regulate decelerate and wheel slip rate, and an optimal regenerative strategy is proposed to recover braking energy. At last, the experiment of brake unit is completed to verify that this novel unit is technologically feasible, and an electric vehicle co-simulation model based on MATLAB/Simulink and AMESim is established to prove that this novel unit is able to significantly improve braking performance of electric vehicle. The simulation result shows braking distance and time are shorten by 12.19% and 15.54% respectively compared with conventional ABS system in the same braking condition, and the recovery efficiencies in light and heavy braking are 53% and 28% respectively.

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In order to effectively improve the vehicle safety, this paper proposed an electronic brake force distribution scheme and an anti-lock brake scheme for passenger car based on a novel brake-by-wire system. The brake-by-wire system was introduced at first, then the electronic brake force distribution scheme and anti-lock brake scheme are designed after analyzing of brake system and vehicle model. At last, the experiment is accomplished to prove the feasibility of the novel brake-by-wire actuator, and the co-simulations of vehicle based on Matlab/Simulink and AMESim are accomplished for typical braking process to prove the superiority of proposed brake-by-wire system and brake scheme. On the one hand, the experiment and simulation results show that the proposed electronic brake force distribution scheme is able to distribute the braking force according to braking intensity and conditions. So the β curve can as close as possible to the I curve. On the other hand, the anti-lock brake scheme is able to accurately regulate the wheel slip rate and adapt to different brake intensity. So the anti-lock brake scheme processes strong robust performance.KEY WORDS: brake-by-wire, linear motor, electric brake force distribution, anti-lock brake, fuzzy control (B1)

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