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Vehicle validation for pressure estimation algorithms of decoupled EHB based on actuator characteristics and vehicle dynamics

DIAS Automotive Electronics Co.,.Ltd.-Songyun Xu
Tongji University-Wei Han, Lu Xiong, Zhuoping Yu
  • Technical Paper
  • 2020-01-0210
To be published on 2020-04-14 by SAE International in United States
In the automotive field, electro-hydraulic brake systems (EHB) has been developed to take place of the vacuum booster, having the advantage of faster pressure built-up and continuously pressure regulation. Most of the pressure control solutions are based on standard pressure-based feedback control, requiring a pressure signal. Although the pressure sensor can produce the pressure feedback signal, it will increase cost and enlarge installation space. The rotation angle of electric motor is available by the built-in sensor, so the pressure can be estimated by using the rotation angle. The pressure control is influenced intensely by the typical nonlinearities (i.e. friction, pressure-position relationship) and uncertainties (i.e. brake pads wear, temperature effect). To address these issues, this work improves an interconnected pressure estimation algorithm based on actuator characteristics [W. Han, L. Xiong, and Z. Yu, “Pressure estimation algorithms in decoupled electro-hydraulic brake system considering the friction and pressure-position relationship,” SAE Technical Paper 2019-01-0438, 2019] by introducing the vehicle dynamics and validates it via vehicle tests. The mathematical model of the motor-type EHB is built. The Gauss exponential model…
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Pressure Estimation Algorithms in Decoupled Electro-Hydraulic Brake System Considering the Friction and Pressure-Position Relationship

Lu Xiong
Tongji University-Wei Han, Zhuoping Yu
Published 2019-04-02 by SAE International in United States
This paper presents several pressure estimation algorithms (PEAs) for a decoupled electro-hydraulic brake system (EHB), which is driven by an electric motor + reduction gear. Most of the pressure control solutions are based on standard pressure-based feedback control, requiring a pressure signal. Although the pressure sensor can produce the pressure feedback signal, it will increase cost and enlarge installation space. The rotation angle of electric motor is available by the built-in sensor, so the pressure can be estimated by using the rotation angle. Considering the typical nonlinearities (i.e. friction, pressure-position relationship) and uncertainties (i.e. disturbance caused by friction model), the estimation-oriented model is established. The LuGre model is selected to describe the friction, and the pressure-position relationship is fitted by a quadratic polynomial. Based on the estimation-oriented model, the force-based PEA (FPEA) and the interconnected PEA (IPEA) are designed, respectively. What makes these two PEAs different is that the IPEA considers the pressure-position relationship. The comparison and analysis of the proposed PEAs have been conducted via some typical ordinary braking scenarios. The sensitivity analysis has…
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Coordinated Control under Transitional Conditions in Hybrid Braking of Electric Vehicle

Tongji Univ.-Zhuoping Yu, Biaofei Shi, Lu Xiong, Wei Han
Published 2018-10-05 by SAE International in United States
In the hybrid brake system of electric vehicle, due to the limitation of the motor braking force when the motor is at high speed and the failure of the regenerative braking force when the motor is at low speed, there are three transitional conditions in hybrid braking: the hydraulic brake system intervenes the braking, the hydraulic brake system withdraws the braking and the regenerative braking force withdraws the braking. Due to the response speed of the hydraulic system is slower than that of the motor, there is a large braking impact (the derivative of braking deceleration) in the transitional conditions of hybrid braking, which deteriorates the smoothness and comfort in braking. Aiming at the impact caused by the poor cooperation between the hydraulic braking force and the motor braking force, a coordinated strategy of double closed-loop feedback and motor force correction is proposed in this paper. The double closed-loop feedback strategy relies on the motor force to compensate the tracking error of hydraulic pressure of the hydraulic brake system. The purpose of the motor force…
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Efficient Supercapacitors Based on Co9S8/Graphene Composites for Electric Vehicles

SAE International Journal of Alternative Powertrains

JIlin University-Yu Yang, Fangwu Ma, Wei Han, Junzhi Li, Junming Cao, Ying Zhao, Liang Wu
  • Journal Article
  • 2018-01-0440
Published 2018-04-03 by SAE International in United States
Nowadays, SC is recognized as a key element of hybrid energy storage system in modern energy supply chain for electric vehicles (EVs). Co9S8 as a promising electrode material attracts much attention for supercapacitor owing to its superior electrochemical capacity. However, its poor stability and electronic conductivity, which result in inferior cycling performance and rate capability, have seriously limited the practical application of Co9O8 in supercapacitors.In this article, Co9S8 nanoparticles were embedded in reduced graphene oxide (rGO) via a simple anneal approach as high efficient and stable electrodes for SCs. The Co9S8/rGO composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The Co9S8 nanoparticles were inserted tightly between the rGO layers due to strong intermolecular forces, preventing the cluster in reduction process of rGO from graphene oxide (GO). The rGO provides the conductive network for Co9S8 and shortens the ion diffusion paths, improving rate performance and enhancing the stability of the electrode material. The as-prepared Co9S8/rGO takes full advantages of high capacitance performance of Co9S8 nanoparticles and excellent conductivity…
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Adaptive Cascade Optimum Braking Control Based on a Novel Mechatronic Booster

Tongji University-Wei Han, Lu Xiong, Zhuoping Yu, Haocheng Li
Published 2017-09-17 by SAE International in United States
BBW (Brake-by-wire) can increase the electric and hybrid vehicles performance and safety. This paper proposes a novel mechatronic booster system, which includes APS (active power source), PFE (pedal feel emulator), ECU (electronic control unit). The system is easily disturbed when the system parameters and the outside conditions change. The system performance is weakened. The cascade control technique can be used to solve the problem. This paper develops an adaptive cascade optimum control (ACOC) algorithm based on the novel mechatronic booster system. The system is divided into main loop and servo loop, both of them are closed-loop system. The servo-loop system can eliminate the disturbance which exists in the servo loop. So the robustness of the cascade control system is improved than which of the general closed-loop control system. Different control object is respectively chosen. The control-oriented mathematical model is designed. Based on the control-oriented model, optimum control algorithm(LQR) is used to design the servo-loop controller for optimum error and rapid response. To eliminate the system uncertainty and control the hydraulic pressure accurately, adaptive control algorithm,…
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Hydraulic Control of Integrated Electronic Hydraulic Brake System Based on LuGre Friction Model

Tongji University-Haocheng Li, Zhuoping Yu, Lu Xiong, Wei Han
Published 2017-09-17 by SAE International in United States
In this paper, an integrated electronic hydraulic brake(I-EHB) system is introduced, which is mainly composed of a motor, a worm gear, a worm, a gear, a rack etc. The friction leads the system to the creeping phenomenon and the dead zone. These phenomenon seriously affect the response speed and the hydraulic pressure control .In order to realize the accurate hydraulic pressure control of I-EHB system, a new friction compensation control method is proposed based on LuGre dynamic friction model. And the theoretical design of adaptive control method is designed based on the feedback of the master cylinder pressure and the operating state of the system. Then the stability of the control method is proved by Lyapunov theorem. A co-simulation model is built with Matlab/Simulink and AMESim, so as to prove the validity of the control method. Related experiments are carried out to track the different target signals, which is step signal, (different amplitude and frequency) sine wave signal and Artemis signal. Compared with the test result with PID control method or compensation control method based…
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Architecture of iBus: A Self-Driving Bus for Public Roads

Tsinghua University-Wei Han, Xinyu Zhang, Jialun Yin, Yutong Li, Deyi Li
Published 2017-03-28 by SAE International in United States
Safety of buses is crucial because of the large proportion of the public transportation sector they constitute. To improve bus safety levels, especially to avoid driver error, which is a key factor in traffic accidents, we designed and implemented an intelligent bus called iBus. A robust system architecture is crucial to iBus. Thus, in this paper, a novel self-driving system architecture with improved robustness, such as to failure of hardware (including sensors and controllers), is proposed. Unlike other self-driving vehicles that operate either in manual driving mode or in self-driving mode, iBus offers a dual-control mode. More specifically, an online hot standby mechanism is incorporated to enhance the reliability of the control system, and a software monitor is implemented to ensure that all software modules function appropriately. The results of real-world road tests conducted to validate the feasibility of the overall system confirm that iBus is reliable and robust.
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An Integrated-Electro-Hydraulic Brake System for Active Safety

Tongji University-Zhuoping Yu, Songyun Xu, Lu Xiong, Wei Han
Published 2016-04-05 by SAE International in United States
An integrated-electro-hydraulic brake system (I-EHB) is presented to fulfill the requirements of active safety. Because I-EHB can control the brake pressure accurately and fast. Furthermore I-EHB is a decoupled system, so it could make the maximum regenerative braking while offers the same brake pedal feeling and also good for ADAS and unmanned driving application. Based on the analysis of current electrohydraulic brake systems, regulation requirements and the requirements for brake system, the operating mode requirements of I-EHB are formed. Furthermore, system topological structure and a conceptual design are proposed. After the selection of key components, the parameter design is accomplished by modeling the system. According to the above-mentioned design method, an I-EHB prototype and test rig is made. Through the test rig, characteristics of the system are tested. Results show that this I-EHB system responded rapidly. Upon the experimental results, increasing pressure response time (T90) of I-EHB is 53% shorter than that of conventional brake system and reducing pressure response time (T10) of I-EHB is 70% shorter than that of conventional brake system. The tracking…
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