Development of an Integrated Control Strategy Consisting of an Advanced Torque Vectoring Controller and a Genetic Fuzzy Active Steering Controller

Replicated with permission by SAE Copyright © 2017 SAE International. Further distribution of this material is not permitted without prior permission from SAE.The optimum driving dynamics can be achieved only when the tire forces on all four wheels and in all three coordinate directions are monitored and controlled precisely. This advanced level of control is possible only when a vehicle is equipped with several active chassis control systems that are networked together in an integrated fashion. To investigate such capabilities, an electric vehicle model has been developed with four direct-drive in-wheel motors and an active steering system. Using this vehicle model, an advanced slip control system, an advanced torque vectoring controller, and a genetic fuzzy active steering controller have been developed previously. This paper investigates whether the integration of these stability control systems enhances the performance of the vehicle in terms of handling, stability, path-following, and longitudinal dynamics. An integrated approach is introduced that distributes the required control effort between the in-wheel motors and the active steering system. Several test maneuvers are simulated to demonstrate the performance and effectiveness of the integrated control approach, and the results are compared to those obtained using each controller individually. Finally, the integrated controller is implemented in a hardware- and operator-in-the-loop driving simulator to further evaluate its effectiveness.Funding for this work was provided by the Natural Sciences and Engineering Research Council of Canada and agrant from AUTO21, a Canadian Network of Centres of Excellenc

Estudo de modelagem de veículos elétricos e estratégia de controle de torque para sistemas de frenagens regenerativa e antitravamento

Orientador: José Antenor PomilioTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Os veículos elétricos têm despertado crescente interesse devido à sua capacidade para reduzir a poluição no meio ambiente, usando elementos de energia elétrica acumulado em baterias e supercapacitores para o acionamento da máquina elétrica no lugar de um motor de combustão interna. Por outro lado, a baixa autonomia do veículo elétrico continua sendo uma barreira para seu sucesso comercial. Instituções automobilísticas junto com a Academia enfrentam esse desafio com diversas soluções para aumentar a energia disponível. Entre as possibilidades está a frenagem regenerativa. A frenagem regenerativa é um processo no qual recupera-se energia de um veículo durante as desacelerações. Esta pesquisa se concentra nas frenagens para diversas condições com mudanças da superficie da estrada, considerando o sistema de frenagem regenerativo e o sistema de antibloqueio. Analisamos e revisamos os aspectos básicos da modelagem de um veículo com/sem ABS, assim como o comportamento dinâmico das rodas e mostramos uma contribuição para o estudo do controle de torque na máquina e estratégias de controle para o torque distribuído na combinação e cooperação entre o torque elétrico e o mecânico, mesmo com mudanças do solo e de métodos de operação, como descidas, obtendo estabilidade do veículo e recuperação de energiaAbstract: The interest in electric vehicles has grown worldwide due to their efficiency for reducing environmental pollution, by using energy elements such as batteries and supercapacitors to drive the electric machine, instead of an internal combustion engine. Contrarily, the low vehicle autonomy remains a barrier to their commercial success. Therefore, automotive institutions together with academics face the challenge through various solutions to increase the available energy. The regenerative braking is one of the implementations that helps a better use of the stored energy. Regenerative braking is a process in which energy is recovered from a vehicle during decelerations. This research focuses on braking for various road surface conditions. Furthermore, it considers the regenerative braking and the anti-lock braking systems regarding energy recovery performance for friction coefficient changes. In this work, we will review and analyze the basic aspects of the modeling of a vehicle with or without ABS, as well as the dynamic behavior of wheels. We will also present a contribution to the study of torque control and control strategies for the torque distribution regarding combination and co-operation between electric and mechanical torque. This process is done despite changes in ground surfaces and operating methods such as downhill, leading to better performance in the flexibility of vehicle stability and in the recovery of powerDoutoradoEnergia EletricaDoutora em Engenharia Elétrica149810/2013-0CAPESCNP

A Study on the Integration of a High-Speed Flywheel as an Energy Storage Device in Hybrid Vehicles

The last couple of decades have seen the rise of the hybrid electric vehicle as a compromise between the outstanding specific energy of petrol fuels and its low-cost technology, and the zero tail-gate emissions of the electric vehicle. Despite this, considerable reductions in cost and further increases in fuel economy are needed for their widespread adoption. An alternative low-cost energy storage technology for vehicles is the high-speed flywheel. The flywheel has important limitations that exclude it from being used as a primary energy source for vehicles, but its power characteristics and low-cost materials make it a powerful complement to a vehicle's primary propulsion system. This thesis presents an analysis on the integration of a high-speed flywheel for use as a secondary energy storage device in hybrid vehicles. Unlike other energy storage technologies, the energy content of the flywheel has a direct impact on the velocity of transmission. This presents an important challenge, as it means that the flywheel must be able to rotate at a speed independent of the vehicle's velocity and therefore it must be coupled via a variable speed transmission. This thesis presents some practical ways in which to accomplish this in conventional road vehicles, namely with the use of a variator, a planetary gear set or with the use of a power-split continuously variable transmission. Fundamental analyses on the kinematic behaviour of these transmissions particularly as they pertain to flywheel powertrains are presented. Computer simulations were carried out to compare the performance of various transmissions, and the models developed are presented as well. Finally the thesis also contains an investigation on the driving and road conditions that have the most beneficial effect on hybrid vehicle performance, with a particular emphasis on the effect that the road topography has on fuel economy and the significance of this

Electric Vehicle Efficient Power and Propulsion Systems

Vehicle electrification has been identified as one of the main technology trends in this second decade of the 21st century. Nearly 10% of global car sales in 2021 were electric, and this figure would be 50% by 2030 to reduce the oil import dependency and transport emissions in line with countries’ climate goals. This book addresses the efficient power and propulsion systems which cover essential topics for research and development on EVs, HEVs and fuel cell electric vehicles (FCEV), including: Energy storage systems (battery, fuel cell, supercapacitors, and their hybrid systems); Power electronics devices and converters; Electric machine drive control, optimization, and design; Energy system advanced management methods Primarily intended for professionals and advanced students who are working on EV/HEV/FCEV power and propulsion systems, this edited book surveys state of the art novel control/optimization techniques for different components, as well as for vehicle as a whole system. New readers may also find valuable information on the structure and methodologies in such an interdisciplinary field. Contributed by experienced authors from different research laboratory around the world, these 11 chapters provide balanced materials from theorical background to methodologies and practical implementation to deal with various issues of this challenging technology. This reprint encourages researchers working in this field to stay actualized on the latest developments on electric vehicle efficient power and propulsion systems, for road and rail, both manned and unmanned vehicles

Integrated vehicle dynamics control using active steering, driveline and braking

This thesis investigates the principle of integrated vehicle dynamics control through proposing a new control configuration to coordinate active steering subsystems and dynamic stability control (DSC) subsystems. The active steering subsystems include Active Front Steering (AFS) and Active Rear Steering (ARS); the dynamic stability control subsystems include driveline based, brake based and driveline plus brake based DSC subsystems. A nonlinear vehicle handling model is developed for this study, incorporating the load transfer effects and nonlinear tyre characteristics. This model consists of 8 degrees of freedom that include longitudinal, lateral and yaw motions of the vehicle and body roll motion relative to the chassis about the roll axis as well as the rotational dynamics of four wheels. The lateral vehicle dynamics are analysed for the entire handling region and two distinct control objectives are defined, i.e. steerability and stability which correspond to yaw rate tracking and sideslip motion bounding, respectively. Active steering subsystem controllers and dynamic stability subsystem controller are designed by using the Sliding Mode Control (SMC) technique and phase-plane method, respectively. The former is used as the steerability controller to track the reference yaw rate and the latter serves as the stability controller to bound the sideslip motion of the vehicle. Both stand-alone controllers are evaluated over a range of different handling regimes. The stand-alone steerability controllers are found to be very effective in improving vehicle steering response up to the handling limit and the stand-alone stability controller is found to be capable of performing the task of maintaining vehicle stability at the operating points where the active steering subsystems cannot. Based on the two independently developed stand-alone controllers, a novel rule based integration scheme for AFS and driveline plus brake based DSC is proposed to optimise the overall vehicle performance by minimising interactions between the two subsystems and extending functionalities of individual subsystems. The proposed integrated control system is assessed by comparing it to corresponding combined control. Through the simulation work conducted under critical driving conditions, the proposed integrated control system is found to lead to a trade-off between stability and limit steerability, improved vehicle stability and reduced influence on the longitudinal vehicle dynamics

Development of a Fuzzy Slip Control System for Electric Vehicles with In-wheel Motors

Replicated with permission by SAE Copyright © 2017 SAE International. Further distribution of this material is not permitted without prior permission from SAE.A two-passenger all-wheel drive urban electric vehicle (AUTO21EV) with four direct-drive in-wheel motors and an active steering system has been designed and developed at the University of Waterloo. A novel fuzzy slip control system is developed for this vehicle using the advantage of four in-wheel motors. A conventional slip control system uses the hydraulic brake system in order to control the tire slip ratio, which is the difference between the wheel center velocity and the velocity of the tire contact patch along the wheel plane, thereby influencing the longitudinal dynamics of a vehicle. The advantage of the proposed fuzzy slip controller is that it acts as an ABS system by preventing the tires from locking up when braking, as a TCS by preventing the tires from spinning out when accelerating. More importantly, the proposed slip controller is also capable of replacing the entire hydraulic brake system of the vehicle by automatically distributing the braking force between the wheels using the available braking torque of the in-wheel motors. In this regard, the proposed fuzzy slip controller guarantees the highest traction or braking force on each wheel on every road condition by individually controlling the slip ratio of each tire with a much faster response time. The performance of the proposed fuzzy slip controller is confirmed by driving the AUTO21EV through several test maneuvers using a driver model in the simulation environment. As the final step, the fuzzy slip controller is implemented in a hardware- and operator-in-the-loop driving simulator and its performance and effectiveness is confirmed.Funding for this work was provided by the Natural Sciences and Engineering Research Council of Canada(NSERC) and a grant from AUTO21, a Canadian Network of Centres of Excellence

전륜 구동 차량의 핸들링 성능을 위한 전자식 차동 제한 장치의 예측 제어 전략

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 기계항공공학부, 2020. 8. 이경수.This dissertation focused on a predictive control strategy for improved handling and acceleration performance of front-wheel-drive vehicles with electronic limited slip differential. Conventional front-wheel-drive cars have certain disadvantages, including a lack of accelerating performance and excessive understeer during acceleration in turn, due to the fact that spin of the inner driving wheel can occur with a small vertical load on the wheel. To address this problem, control logic is proposed for an electronic limited slip differential (ELSD) to enhance handling and acceleration performance. The proposed ELSD control algorithm consists of four parts. (1) Understeer prevention logic is developed for acceleration in turn. First, for a rapid response, the driving torque is distributed in advance to the inner and outer wheels according to the magnitude of the estimated traction potential in the wheels. If wheel spin occurs because of insufficient inner grip, then additional driving torque is transmitted to the outer wheel in proportion to the increment of the inner wheel speed compared to the outer wheel. However, the torque transfer to the outer wheel is limited in proportion to the excess speed of the outer wheel compared to the non-driving wheel to prevent power slides. (2) Oversteer prevention logic can reduce overshooting yaw motion during severe lane changes. The algorithm transmits driving torque from the outer wheel to the inner wheel in proportion to the level of excess yaw rate relative to the target yaw rate. (3) A cooperative control strategy with an electronic stability control (ESC) system is developed to decouple the ELSD/ESC system from the overlapped control timing. (4) Steering feel compensation logic is applied to the electric power-assist steering to prevent a torque steer effect caused by torque bias. The performance of the proposed algorithm has been investigated via vehicle tests. The proposed algorithm has been verified through patents on the control method and friction estimation approach for the novelty of this research. The ELSD with the proposed algorithm was then applied to mass production. This approach received positive feedback from international media due to the significant improvements in vehicle performance via ELSD. The system with the proposed algorithm also was won the IR52 Jang Young-shil Award for its technological importance, originality, economic value, and technical spill-over.논문은 전륜 구동 차량의 핸들링 및 가속 성능 향상을 위한 전자식 차동 제한 장치, Electronic Limited Slip Differential (ELSD)의 예측 제어 전략에 초점을 맞췄다. 기존 전륜 구동 차는 바퀴에 작은 수직하중으로 선회 내측 구동 휠의 스핀이 발생할 수 있기 때문에 선회 중 가속 시 가속 성능 면에서 불리하고 언더스티어가 과해지는 등 전형적인 단점이 있다. 이 문제를 해결하기 위해 ELSD에 대한 제어 로직을 제안하여 조종안정성 및 가속 성능을 향상시켰다. 제안된 전자식 차동제한장치 제어 알고리즘은 네 부분으로 구성된다. (1) 선회 중 가속 성능 향상을 위해 언더스티어 방지 로직을 제안하였다. 첫째, 빠른 응답을 위해 휠의 구동 가능 접지력 추정 값의 크기에 따라 선회 내측 및 외측 휠에 구동 토크를 미리 분배한다. 그래도 선회 내측 접지력이 부족하여 휠 스핀이 발생하는 경우, 외측 휠 속도 대비 내측 휠 속도의 초과량에 비례하여 추가 구동 토크를 외측 휠로 전달한다. 다만 외측 휠의 스핀은 절대로 허용하지 않기 위해 비구동 휠 속도 대비 구동 외측 휠 속도의 초과량에 비례하여 외측 휠로의 토크 전달을 제한한다. (2) 오버스티어 방지 로직은 심한 차선 변경 시 과한 요 거동을 안정화할 수 있다. 알고리즘은 목표 요 속도 대비 실제 차량의 요 속도 초과량에 비례하여 선회 외측 휠에서 내측 휠로 구동 토크를 전달한다. (3) Electronic Stability Control (ESC) 시스템과의 협조 제어 전략은 구동 토크와 제동 토크의 중복으로부터 ELSD/ESC 시스템을 분리하기 위해 제안되었다. (4) 조향 반력 토크 보상 제어 로직은 좌/우 구동 토크 차이로 인한 토크 스티어 효과를 방지하기 위해 전기식 파워 보조 조향 시스템에 보상 토크를 인가한다. 본 알고리즘은 차량 테스트를 통해 평가되었다. 제안된 알고리즘은 제어 방법과 마찰 추정 방법에 대한 특허를 통해 독창성을 검증 받았다. 그리고 제안된 알고리즘이 적용된 ELSD는 고성능 양산 차량에 적용되었다. 그 후, ELSD로 인해 차량 성능 크게 향상된 부분과 관련하여 국외 매체로부터 긍정적인 피드백을 받았다. 또한 제안된 알고리즘이 적용된 시스템은 IR52 장영실상을 수상하여, 기술적 중요성, 독창성, 경제적 가치, 기술적 파급력을 검증 받았다.Table of Contents Chapter 1. Introduction 1 1.1 Background and Motivation 1 1.2 Previous Researches 3 1.3 Thesis Objectives 10 1.4 Thesis Outline 16 Chapter 2. Analysis of Lateral Torque Transfer of Electronic Limited Slip Differential (ELSD) System 17 Chapter 3. Electronic Limited Slip Differential (ELSD) Handling Control Algorithm Overview 22 Chapter 4. Control Logic for Understeer Prevention 28 4.1 Wheel Spin Predictive Control 29 4.1.1 Model-based Predictive Control Overview 29 4.1.2 Allowable Driving Force Prediction Modeling 32 4.2 Wheel Speed Feedback Control 38 4.2.1 Control for Inner Wheel Spin Prevention 38 4.2.2 Control for Outer Wheel Spin Prevention 40 4.3 US Prevention Control General Summary 43 Chapter 5. Control Logic for Oversteer Prevention 50 5.1 Yaw Rate Feedback Control 51 Chapter 6. Integrated Control of Electronic Stability Control (ESC), Electric Power-assist Steering (EPS), and Electronic Limited Slip Differential (ELSD) 53 6.1 Cooperative Control with ESC 53 6.2 Cooperative Control with EPS 58 Chapter 7. Chapter 7 Tire-road Friction Estimation to Improve the Predictive Control 60 Chapter 8. Validation: Vehicle Tests 66 8.1 Configuration of Vehicle Tests 68 8.2 Closed-loop Acceleration in A Turn 73 8.3 Closed-loop Double Lane Change 80 8.4 Performance Comparison with Competitor 87 Chapter 9. Conclusions and Future Works 90 Bibliography 93 Abstract in Korean 96Docto

Integration of Active Chassis Control Systems for Improved Vehicle Handling Performance

This thesis investigates the principle of integration of vehicle dynamics control systems by proposing a novel control architecture to integrate the brake-based electronic stability control (ESC), active front steering (AFS), normal suspension force control (NFC) and variable torque distribution (VTD). A nonlinear 14 degree of freedom passive vehicle dynamics model was developed in Matlab/Simulink and validated against commercially available vehicle dynamics software CarSim. Dynamics of the four active vehicle control systems were developed. Fuzzy logic and PID control strategies were employed considering their robustness and effectiveness in controlling nonlinear systems. Effectiveness of active systems in extending the vehicle operating range against the passive ones was investigated. From the research, it was observed that AFS is effective in improving the stability at lower lateral acceleration (latac) region with less interference to the longitudinal vehicle dynamics. But its ability diminishes at higher latac regions due to tyre lateral force saturation. Both ESC and VTD are found to be effective in stabilising the vehicle over the entire operating region. But the intrusive nature of ESC promotes VTD as a preferred stability control mechanism at the medium latac range. But ESC stands out in improving stability at limits where safety is of paramount importance. NFC is observed to improve the ability to generate the tyre forces across the entire operating range. Based on this analysis, a novel rule based integrated chassis control (ICC) strategy is proposed. It uses a latac based stability criterion to assign the authority to control the stability and ensures the smooth transition of the control authority amongst the three systems, AFS, VTD and ESC respectively. The ICC also optimises the utilisation of NFC to improve the vehicle handling performance further, across the entire operating regions. The results of the simulation are found to prove that the integrated control strategy improves vehicle stability across the entire vehicle operating region

Traction Control Allocation Employing Vehicle Motion Feedback Controller for Four-wheel-independent-drive Vehicle

A novel vehicle traction algorithm solving the traction force allocation problem based on vehicle center point motion feedback controller is proposed in this paper. The center point motion feedback control system proposed utilizes individual wheel torque actuation assuming all wheels are individually driven. The approach presented is an alternative to the various direct optimization-based traction force/torque allocation schemes. The proposed system has many benefits, such as significant reduction of the algorithm complexity by merging most traction system functionalities into one. Such a system enables significant simplification, unification, and standardization of powertrain control design. Moreover, many signals needed by conventional traction force allocation methods are not required to be measured or estimated with the proposed approach, which are among others vehicle mass, wheel loading (normal force), and vehicle center of gravity location. Vehicle center point trajectory setpoints and measurements are transformed to each wheel, where the tracking is ensured using the wheel torque actuation. The proposed control architecture performance and analysis are shown using the nonlinear twin-track vehicle model implemented in Matlab $\&$ Simulink environment. The performance is then validated using high fidelity FEE CTU in Prague EFORCE formula model implemented in IPG CarMaker environment with selected test scenarios. Finally, the results of the proposed control allocation are compared to the state-of-the-art approach