Comparison between braking and steering yaw moment controllers considering ABS control aspects

Two yaw motion control systems that improve a vehicle lateral stability are proposed in this study: a braking yaw motion controller (BYMC) and a steering yaw motion controller (SYMC). A BYMC controls the braking pressure of the rear inner wheel, while a SYMC steers the rear wheels to allow the yaw rate to track the reference yaw rate. A 15 degree-of-freedom vehicle model, simplified steering system model, and driver model are used to evaluate the proposed BYMC and SYMC. A robust anti-lock braking system (ABS) controller is also designed and developed. The performance of the BYMC and SYMC are evaluated under various road conditions and driving inputs. They reduce the slip angle when braking and steering inputs are applied simultaneously, thereby increasing the controllability and stability of the vehicle on slippery roads. The SYMC performs better than the BYMC because the SYMC vehicle has four-wheel steering. However, both the BYMC and SYMC vehicles show improved performance during lane-change maneuvers.     

Iterative learning control of antilock braking of electric and hybrid vehicles

Hybrid electric vehicles (HEVs) use multiple sources of power for propulsion which provides great ease and flexibility to achieve advanced controllability and additional driving performance. In this paper, the electric motor in HEV and electric vehicle (EV) propulsion systems is used to achieve antilock braking performance without a conventional antilock braking system (ABS). The paper illustrates that the antilock braking of HEV can be easily achieved using iterative learning control for various road conditions. A vehicle model, a slip ratio model, and a vehicle speed observer were developed to control the antilock performance of HEV during braking. Through iterative learning process, the motor torque is optimized to keep the tire slip ratio corresponding to the peak traction coefficient during braking. Simulations were performed on a compact size vehicle to validate the proposed control method. The control algorithm proposed in this paper may also be used for the ABS control of conventional vehicles.     

Energy Management Strategies for Modern Electric Vehicles Using MATLAB/Simulink

The paper describes the various energy management techniques that can be implemented for a modern electric vehicle by using MATLAB/Simulink. The Renault Twizy vehicle is considered for MATLAB simulation. Regenerative braking technique is discussed, in which the kinetic energy is converted to electricity to charge the battery of the vehicle when the brakes are applied or when the vehicle is moving down the hill. A solar photovoltaic (PV) on the roof-top of the vehicle is implemented to charge the battery used in the vehicle. The simulation results are highlighted and energy management strategies are presented. The results showed that the speed control of direct current (DC) motor during the motoring mode and regenerative braking mode was successfully achieved by using a bi-directional DC-DC converter and a proportional-integral (PI) controller at various reference speeds set by the user by applying a variable load torques to the motor. The size of solar PV on roof-top of the vehicle was found to be 280 W that charged the 48 V battery of the vehicle by using a bi-directional DC-DC converter, which was evaluated by using MATLAB/Simulink.     

Modellierung der parallelen Antriebsstränge für ein Hybrid-Elektrofahrzeug vom Typ „Hybrid Through The Road“

Hybrid electric vehicles (HEV) are equipped with an internal combustion engine (ICE) and an electric drive (ED). They are devided into serial and parallel HEVs, depending on the power flow. The ED needs to be controlled. This allows reduction of emissions and the amount of gas. In regenerative braking, the braking energy is converted into electrical energy and fed into a battery. The fuel efficiency of the ICE in the driving state is increased by loading or uploading through ED. Cut off the ICE while standstill reduces the waste of gas. A simulation tool in MATLAB/SIMULINK calculates the amount of gas for an HEV of parallel type for a given driving cycle. The drives are considered as efficiency maps from measured data. The fuel economy of the HEV depends on the driving cycle, the vehicle mass and the engine speed while shift of gears. For a vehicle of Minivan class, the saving is between 17% up to 25% compared to a vehicle driven by an ICE only.     

基于模糊滑模控制的车辆稳定性研究

针对车辆在转弯或变道引起的车辆稳定性控制问题,建立了用于稳定性控制的3自由度非线性动力学模型。文中将车辆横摆角速度、质心侧偏角作为主要控制变量。基于模糊滑模控制理论,采用直接横摆力矩控制方法控制横摆角速度和质心侧偏角,其中考虑到质心侧偏角难以通过传感器测量,设计了基于递归最小二乘法的质心侧偏角估计方法。同时,在基于Matlab与ADMAS联合调试的环境下进行了仿真分析,仿真结果表明该控制器能有效地使横摆角速度和质心侧偏角跟踪其期望值,使汽车保持在安全稳定的范围内。     

Driving characteristics of an electric vehicle system with independently driven front and rear wheels

A new type of electric vehicle drive system, which has independently driven front and rear wheels, is proposed. This structure can distribute the driving and braking torque according to running and load conditions, and provides a fail-safe effect. Moreover, it is possible to improve drivability, steering ability, and stability while running and braking by arranging a permanent magnet synchronous motor and an induction motor for driving the front and rear wheels, respectively. These are important functions for an urban car to easily cope with common situations such as traffic jams and starting and stopping operations, and the special situation of failure of the motor drive system while running on city routes. The functions are verified through simulations and experiments with the bench test equipment equivalent to the actual system.     

Development of a Hybrid Electric Vehicle With a Hydrogen-Fueled IC Engine

The motivation for the use of hydrogen as fuel is that it can be renewable and can reduce emissions. Hydrogen fuel cell vehicles are still likely to be more of a far-term reality because of their high manufacturing cost. A hybrid electric vehicle (HEV) with a hydrogen-fueled internal combustion (IC) engine has the potential of becoming a low-emission low-cost practical solution in the near future. This paper describes a standard sport utility vehicle (SUV) that has been converted into a hydrogen-powered HEV. The powertrain utilizes compressed gaseous hydrogen as fuel, a boosted hydrogen IC engine, an induction motor, a hydraulic transmission, regenerative braking, advanced nickel-metal hybrid batteries, and a real-time control system. Tests show that the vehicle can deliver higher fuel economy and much lower emissions than those of a traditional SUV without compromises in performance. This paper presents an overview of the prototype vehicle and emphasizes some of the unique features of this energy-saving clean environment solution     

基于模糊控制的电动汽车再生制动系统的研究

再生制动能够降低能源的消耗量和延长电动汽车的行驶里程。它广泛的受到诸多学者的关注。本文提出了一个新颖的再生制动控制系统。该系统基于无刷直流电机的控制特性和电动汽车刹车时的制动特性,直流无刷电机采用传统的PID控制,刹车力采用模糊逻辑控制,刹车力矩可以由PID控制器实时的控制。通过Matlab/Simulink软件,仿真分析了电池的充电状态、制动力和直流侧线电流。实验和仿真结果均证实了在具有良好的刹车性能的前提下,该方法可以实现良好的再生制动性能和延长电动汽车的行驶里程,在工程上更加易于实现也具有更好的鲁棒性和更高的效率。     

Control Strategy for a 42-V Waste-Heat Thermoelectric Vehicle

A 42-V waste-heat thermoelectric vehicle is employed as a potential application of thermoelectric generators for fuel economy improvement and emissions reduction. The 42-V waste-heat thermoelectric vehicle currently in development employs an assemblage driving system consisting of a waste-heat thermoelectric generator, a 42-V powernet, and an integrated starter and generator (ISG). The waste-heat thermoelectric generator also functions as a power supply. To optimize the utilization of the waste-heat energy generated by the thermoelectric generator, an electric assist control strategy and a torque split control strategy are proposed herein. Through the development of relevant systems and strategies, including the thermoelectric generator and an electric bus system, two vehicle models are established and compared using the ADVISOR platform based on MATLAB/Simulink. The calculation results show improved fuel economy and emissions performance resulting from the integration of the torque split control strategy into the 42-V waste-heat thermoelectric vehicle.     

Vehicle Yaw Control via Second-Order Sliding-Mode Technique

The problem of vehicle yaw control is addressed in this paper using an active differential and yaw rate feedback. A reference generator, designed to improve vehicle handling, provides the desired yaw rate value to be achieved by the closed loop controller. The latter is designed using the second-order sliding mode (SOSM) methodology to guarantee robust stability in front of disturbances and model uncertainties, which are typical of the automotive context. A feedforward control contribution is also employed to enhance the transient system response. The control derivative is constructed as a discontinuous signal, attaining an SOSM on a suitably selected sliding manifold. Thus, the actual control input results in being continuous, as it is needed in the considered context. Simulations performed using a realistic nonlinear model of the considered vehicle show the effectiveness of the proposed approach.      

数字控制直流调速系统实验平台的研制与应用

基于MATLAB的Simulink仿真环境,设计实现了Windows操作系统下的直流电机数字实时控制系统,为数字控制直流调速系统提供了教学实验平台。硬件驱动程序作为Simulink的一个模块可以被任意调用,控制算法可以用Simulink提供的其它仿真模块或S函数来实现,整个系统开放灵活,可以实现各种算法的实际验证。系统调试结果充分验证了该数字控制系统稳定的运行特性。     

Automobile Brake-by-Wire Control System Design and Analysis

The automobile brake-by-wire (BBW) system, which is also called the electromechanical brake system, has become a promising vehicle braking control scheme that enables many new driver interfaces and enhanced performances without a mechanical or hydraulic backup. In this paper, we survey BBW control systems with focuses on fault tolerance design and vehicle braking control schemes. At first, the system architecture of BBW systems is described. Fault tolerance design is then discussed to meet the high requirements of reliability and safety of BBW systems. A widely used braking model and several braking control schemes are investigated. Although previous work focused on antilock and antislip braking controls on a single wheel basis, we present a whole-vehicle control scheme to enhance vehicle stability and safety. Simulations based on the whole-vehicle braking model validate a proposed fuzzy logic control scheme in the lateral and yaw stability controls of vehicles.     

Directional-stability-aware brake blending control synthesis for over-actuated electric vehicles during straight-line deceleration

For the purpose of both energy regeneration and directional stability enhancement, regenerative and hydraulic blended braking control of an over-actuated electric vehicle equipped with four individual on-board motors during normal straight-line deceleration is studied. System models which include the vehicle dynamics, tire, electric powertrain, and hydraulic brake models are developed. Mechanisms of directional instability of the electric vehicle during straight-line braking are analyzed. To improve the electric vehicle's safety and performance, novel compensation methods through blended braking are studied. On the basis of half-shaft torque estimation, two new regenerative braking control algorithms are proposed. Simulations of the developed control algorithms are carried out during normal straight-line braking maneuvers. The results and discussions demonstrate that the developed approaches are advantageous when compared with the conventional baseline strategy, with respect to both the directional stability and regeneration efficiency, thus validating the feasibility and effectiveness of the controller synthesis.     

Robust Yaw Stability Controller Design and Hardware-in-the-Loop Testing for a Road Vehicle

Unsymmetrical loading on a car like $mu$-split braking, side wind forces, or unilateral loss of tire pressure results in unexpected yaw disturbances that require yaw stabilization either by the driver or by an automatic driver-assist system. The use of two-degrees-of-freedom control architecture known as the model regulator is investigated here as a robust steering controller for such yaw stabilization tasks in a driver-assist system. The yaw stability-enhancing steering controller is designed in the parameter space to satisfy a frequency-domain mixed sensitivity constraint. To evaluate the resulting controller design, a real-time hardware-in-the-loop simulator is developed. Steering tests with and without the controller in this hardware-in-the-loop setup allow the driver to see the effect of the proposed controller to improve vehicle-handling quality. The hardware-in-the-loop simulation setup can also be used for real-time driver-in-the-loop simulation of other vehicle control systems.      

Novel Regenerative Braking Control of Electric Power-Assisted Wheelchair for Safety Downhill Road Driving

This paper describes a novel regenerative braking control scheme of electric power-assisted wheelchairs for safety driving on downhill roads. The ldquoelectric power-assisted wheelchairrdquo which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people; however, it has no braking system to suppress the wheelchair's velocity and brings the dangerous and fearful driving particularly on downhill roads. Therefore, this paper proposes a novel safety and efficient driving control scheme based on the regenerative braking system. This paper applies the regenerative braking system with the step-up chopper circuit serially connecting two motors and realizes the velocity feedback control with the variable duty ratio so that it tracks the optimal velocity based on the minimum Jerk model. In addition, the dynamic braking system is also applied at the low-speed range instead of the regenerative braking in order to suppress the acceleration. Some driving experiments on the practical downhill roads show the effectiveness of the proposed control system.     

Yaw stability control of a steer-by-wire equipped vehicle via active front wheel steering

A novel yaw stability control algorithm with active front wheel steering control of a vehicle equipped with a steer-by-wire system is presented in this paper. The proposed algorithm achieves the decoupling of the lateral and yaw motion of a vehicle and the vehicle’s yaw damping simultaneously by the feedback of both yaw rate and front steering angle. A trade-off is then made between the robust decoupling and yaw rate damping through the adjustment of the feedback gains with respect to vehicle speed. With this trade-off, the gain scheduled steering controller provides the desired yaw rate damping while keeping the yaw-lateral motion decoupled. The robustness of the yaw-lateral decoupling is achievable when arbitrary yaw damping is not required. The proposed control system is implemented on a steer-by-wire vehicle, and the experimental results are presented illustrating the benefits.     

A novel driver assist stability system for all-wheel-drive electric vehicles

A novel driver-assist stability system for all-wheel-drive electric vehicles is introduced. The system helps drivers maintain control in the event of a driving emergency, including heavy braking or obstacle avoidance. The system comprises a fuzzy logic system that independently controls wheel torque to prevent vehicle spin. Another fuzzy wheel slip controller is used to enhance vehicle stability and safety. A neural network is trained to generate the required reference for yaw rate. Vehicle true speed is estimated by a sensor data fusion method. The intrinsic robustness of fuzzy controllers allows the system to operate in different road conditions successfully. Moreover, the ease of implementing fuzzy controllers gives a potential for vehicle stability enhancement.     

六相感应电动机制动仿真及分析

建立六相感应电动机在两相同步旋转d-q坐标系下的动态数学模型,并分析六相电压源型逆变器的空间矢量脉宽调制(SVPWM)技术。在MATLAB/SIMULINK环境下,构建SVPWM电压源型逆变器供电的六相感应电动机的仿真模型,分别进行六相感应电动机能耗制动、反接制动和回馈制动的动态仿真,并分析这三种制动方式的特点,为电力传动系统的设计提供理论依据。     

Modeling, Analysis, and Neural Network Control of an EV Electrical Differential

This paper presents system modeling, analysis, and simulation of an electric vehicle (EV) with two independent rear wheel drives. The traction control system is designed to guarantee the EV dynamics and stability when there are no differential gears. Using two in-wheel electric motors makes it possible to have torque and speed control in each wheel. This control level improves EV stability and safety. The proposed traction control system uses the vehicle speed, which is different from wheel speed characterized by a slip in the driving mode, as an input. In this case, a generalized neural network algorithm is proposed to estimate the vehicle speed. The analysis and simulations lead to the conclusion that the proposed system is feasible. Simulation results on a test vehicle propelled by two 37-kW induction motors showed that the proposed control approach operates satisfactorily.     

Lateral stabilization of a four wheel independent drive electric vehicle on slippery roads

In this paper, a new controller is proposed for lateral stabilization of four wheel independent drive electric vehicles without mechanical differential. The proposed controller has three levels including high, medium and low control levels. Desired vehicle dynamics such as reference longitudinal speed and reference yaw rate are determined by higher level of controller. Moreover, using a neural network observer and a fuzzy logic controller, a novel reference longitudinal speed generator system is presented. This system guarantees the vehicle’s stable motion on the slippery roads. In this paper, a new sliding mode controller is proposed and its stability is proved by Lyapunov stability theorem. This sliding mode control structure is faster, more accurate, more robust, and with smaller chattering than classic sliding mode controller. Based on the proposed sliding mode controller, the medium control level is designed to determine the desired traction force and yaw moment. Therefore, suitable wheel forces are calculated. Finally, the effectiveness of the introduced controller is investigated through conducted simulations in CARSIM and MATLAB software environments.