Study and comparison of non linear and LPV control approaches for vehicle stability control

International audienceThis paper proposes a study and a comparison between two efficient and novel vehicle control dynamics strategies, namely, the non linear Flatness control strategy and the LPV/Hinf control strategy. The first one concerns a controller based on the differential algebraic flatness of non linear systems and an algebraic non linear estimation applied to commercial vehicles. The second one is a LPV/Hinf (Linear Varying Parameter with the Hinf norm ) control using a stability monitoring system to achieve the vehicle dynamics control objective. These two strategies use Active Steering and Electro- Mechanical Braking actuators and aim at improving the vehicle stability and steerability by designing a multivariable controller that acts simultaneously on the lateral and longitudinal dynam- ics of the car. Simulations are performed on a complex nonlinear full vehicle model, the same driving scenario is applied for the two control strategies. The model parameters are those of a Renault Mégane Coupé (see table.I), obtained by identification with real data. Promising simulations results are obtained. Comparison between the two proposed strategies and the uncontrolled vehicle show the reliability and the robustness of the proposed solutions, even if one is governed within the linear control framework while the other one is a non linear control approach

A Review of Active Yaw Control System for Vehicle Handling and Stability Enhancement

Yaw stability control systemplays a significant role in vehicle lateral dynamics in order to improve the vehicle handling and stability performances. However, not many researches have been focused on the transient performances improvement of vehicle yaw rate and sideslip tracking control. This paper reviews the vital elements for control system design of an active yaw stability control system; the vehicle dynamic models, control objectives, active chassis control, and control strategies with the focus on identifying suitable criteria for improved transient performances. Each element is discussed and compared in terms of their underlying theory, strengths, weaknesses, and applicability. Based on this, we conclude that the sliding mode control with nonlinear sliding surface based on composite nonlinear feedback is a potential control strategy for improving the transient performances of yaw rate and sideslip tracking control

Global Chassis Control System Using Suspension, Steering, and Braking Subsystems

A novel Global Chassis Control (GCC) system based on a multilayer architecture with three levels: top: decision layer, middle: control layer, and bottom: system layer is presented. The main contribution of this work is the development of a data-based classification and coordination algorithm, into a single control problem. Based on a clustering technique, the decision layer classifies the current driving condition. Afterwards, heuristic rules are used to coordinate the performance of the considered vehicle subsystems (suspension, steering, and braking) using local controllers hosted in the control layer. The control allocation system uses fuzzy logic controllers. The performance of the proposed GCC system was evaluated under different standard tests. Simulation results illustrate the effectiveness of the proposed system compared to an uncontrolled vehicle and a vehicle with a noncoordinated control. The proposed system decreases by 14% the braking distance in the hard braking test with respect to the uncontrolled vehicle, the roll and yaw movements are reduced by 10% and 12%, respectively, in the Double Line Change test, and the oscillations caused by load transfer are reduced by 7% in a cornering situation

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

The INOVE ANR 2010 Blan 0308 project: Integrated approach for observation and control of vehicle dynamics

International audienceThis paper presents the INOVE "Integrated approach for observation and control of vehicle dynamics" project. The aim and organization of the project are described and we present some recent results on the proposed integrated approach to design new methodologies for the improvement of the vehicle dynamical behaviour

Mitigating Instability in Electric Drive Vehicles Due to Time Varying Delays with Optimised Controller

The instability in the Electric vehicle would reduce the performance and even severely damage the system. This instability is mainly due to the random time-varying delays occurring in CAN network and the improper efficiency of controllers. This uncertainty and error occurrence makes it difficult to design the electric vehicles considering the advantages of Electric Vehicles being, the future to reduce harmful emissions due to fossil fuels, the instability can be mitigated by using optimized H∞ controller. The results of Simulations through MATLAB demonstrate the Effectiveness of the improved controller by comparing with the normal PI controller. The results of comparison illustrate the strength of explicitly

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

극한 주행 핸들링 성능 개선을 위한 토크벡터링 제어 알고리즘

학위논문(박사) -- 서울대학교대학원 : 공과대학 기계공학부, 2023. 2. 이경수.This dissertation comprehensively details the design of a torque vectoring control algorithm for enhanced cornering performance using two front in-wheel motors (IWMs) and electronic limited slip differential (eLSD) at the rear axle. The main scopes to be covered in this dissertation can be divided into two categories: 1) individual control of IWM for torque vectoring control at the front axle; 2) integrated control of IWM and eLSD for both front and rear axle. First, an individual control strategy of two front IWMs in a rear-wheel-drive vehicle has been designed to improve the cornering performance. The individual control of IWMs consists of steady-state and transient control input. The steady-state control input is devised to improve the steady-state cornering response with modifying the vehicle understeer gradient, and the transient control input is designed to enhance the lateral stability by increasing the yaw rate damping coefficient. The proposed algorithm has been investigated through both computer simulations and vehicle tests, in order to show that the proposed algorithm can enhance the cornering response achieving the control objectives and to show the superior control performance compared to the other cases, such as yaw rate tracking algorithm and uncontrolled case. Second, the integrated control of two front IWMs and eLSD is designed to enhance the cornering performance at high speeds considering the characteristics of each actuator. The two front IWMs are controlled to improve the cornering performance based on a feedforward control, and the eLSD is utilized for the yaw rate feedback control. The computer simulations are conducted to show the effects of each actuator on the vehicle lateral motion at aggressive cornering with longitudinal acceleration and deceleration. Additionally, vehicle test results show that the proposed controller improves the cornering performance at the limits of handling compared to the uncontrolled case. In summary, this dissertation proposes a control algorithm for an enhanced limit handling performance based on vehicle understeer gradient and yaw rate damping characteristics, addressing also integrated control of in-wheel motors and electronic limited slip differential with considering the characteristics of each actuator. The proposed IWM control law is formulated to shape the understeer characteristics during steady-state cornering and yaw rate damping characteristic during transient cornering, and the eLSD control is designed to track the reference yaw rate. Computer simulations and vehicle tests are conducted to validate the control performance of the proposed algorithm, showing significant improvements in the agility and the stability of a test vehicle without chattering issues. Additionally, the vehicle tests at a racing track confirm the enhanced limit handling performance.본 논문은 전륜 인휠모터와 후륜 전자식 차동 제한 장치를 이용하여 선회 성능 개선을 위한 토크벡터링 제어 알고리즘에 대해 포괄적으로 설명하였다. 본 논문에서 다루는 주요 연구 범위는 크게 두 가지 범주로 나뉠 수 있다. 첫 번째는 전륜 인휠모터를 이용한 개별적인 토크벡터링 제어이고, 두 번째는 전륜 인휠모터 및 후륜 전자식 차동제한장치를 모두 이용한 전후륜 통합 토크벡터링 제어이다. 첫 번째로, 후륜 구동 차량 내에서 두 개의 전륜 인휠 모터를 활용한 선회 성능 개선을 위한 제어 알고리즘이 설계되었다. 인휠 모터 독립 제어는 정상상태 제어 입력과 과도응답 상태 제어 입력으로 구성되어 있다. 정상상태 제어 입력은 차량의 언더스티어 구배를 변형하면서 정상상태 선회 반응을 개선하기 위해 고안되었고, 과도응답 상태 제어 입력은 차량의 요댐핑 계수를 증가시킴으로써 차량의 횡방향 안정성을 개선하기 위해 설계되었다. 제안된 알고리즘의 성능은 컴퓨터 시뮬레이션과 차량 실험을 통해 확인하였다. 실험 결과에서 알 수 있듯이, 제안된 알고리즘은 제어 목표를 달성하며 차량의 선회 성능을 개선할 수 있었다. 두 번째로, 각 엑츄에이터의 특성을 고려하고 고속 주행 상황에서의 선회 성능을 개선하기 위해, 두 개의 전륜 인휠 모터와 후륜의 전자식 차동 제한 장치의 통합 제어 알고리즘이 설계되었다. 두 개의 전륜 인휠 모터는 피드포워드 제어를 기반으로 선회 성능을 개선하기 위해 제어되었고, 후륜의 전자식 차동 제한 장치는 요레이트 피드백 제어를 위해 활용되었다. 컴퓨터 시뮬레이션은 감가속을 포함한 공격적인 선회 상황에서 각 엑츄에이터의 제어 효과를 보여주기 위해 수행되었다. 추가적으로, 차량 실험 결과를 통해 제안된 제어기가 제어되지 않은 경우에 비해 핸들링 한계 상황에서의 선회 성능을 개선할 수 있다는 점을 보여주었다. 요약하자면, 본 연구에서는 차량의 언더스티어 그레디언트와 요레이트 댐핑 특성에 기반한 한계 핸들링 성능 개선을 위한 제어 알고리즘을 제안하였다. 또한, 인휠모터와 전자식 차동 제한 장치의 각 엑츄에이터 특성을 고려하여 인휠모터와 전자식 차동 제한 장치의 통합 제어에 대해 다루었다. 제안된 인휠모터 제어기는 정상상태 선회에서의 언더스티어 그레디언트와 과도응답상태 선회에서의 요레이트 댐핑 특성을 변형하기 위해 고안되었고, 전자식 차동 제한 장치 제어는 목표 요레이트를 추종하기 위해 설계되었다. 제안된 제어기를 검증하기 위해, 컴퓨터 시뮬레이션과 실차 실험이 진행되었고, 차량의 선회 안정성과 민첩성이 채터링 문제없이 확연히 개선된다는 것을 보여주었다. 추가적으로, 레이싱 트랙에서의 실차 실험을 통해 개선된 한계 핸들링 성능 또한 제시되었다.Chapter 1. Introduction 1 1.1. Background and motivation 1 1.2. Previous research on considering tire characteristics 4 1.2. Previous research on vehicle controller design 8 1.3. Thesis objectives 13 1.4. Thesis outline 15 Chapter 2. Vehicle Control System 17 2.1. Vehicle chassis system 17 2.2. Vehicle tire-road interactions 22 2.3. Tire characteristics at the limits of handling 35 Chapter 3. Torque Vectoring Control with In-Wheel Motors (IWMs) 49 3.1. Upper level controller 53 3.1.1. Control strategies for steady-state response 54 3.1.2. Control strategies for transient response 57 3.1.3. Analysis on the closed-loop system with proposed controller 60 3.2. Lower level controller 65 3.2.1. Actuator characteristics of in-wheel motors 65 3.2.2. Torque inputs for yaw moment generation 66 Chapter 4. Integrated Control of Two Front In-Wheel Motors (IWMs) and Rear-Axle Electronic Limited Slip Differential (eLSD) 68 4.1. Upper level controller 71 4.1.1. Analysis on actuator characteristics and vehicle responses 71 4.1.2. Feedforward control using in-wheel motors 79 4.1.3. Feedback control using electronic limited slip differential 80 4.2. Lower level controller 82 4.2.1. Transforming the desired yaw moments to the torque command 82 4.2.2. Saturating the torque inputs considering the actuator and tire friction limit 83 4.2.3. Transferring the eLSD clutch torque in the desired direction 84 Chapter 5. Simulation Results 87 5.1. Effect of IWM control on vehicle motion 87 5.2. Effect of IWM/eLSD integrated control 98 Chapter 6. Vehicle Test Results 108 6.1. Test results for IWM control 108 6.2. Test results for integrated control of IWM and eLSD 116 Chapter 7. Conclusion 121 Appendix A. Integrated control of two front in-wheel motors and rear wheel steering 123 A.1. Prediction model for vehicle motion 124 A.2. Controller design 128 A.3. Simulation results 131 Bibliography 138 Abstract in Korean 148박