Jangyeol Yoon

An investigation into unified chassis control scheme for optimised vehicle stability and manoeuvrability

This paper describes a unified chassis control (UCC) strategy to improve the lateral stability andmanoeuvrability of vehicles by integrating individual chassis control modules such as electronic stability control (ESC), active front steering (AFS) and continuous damping control (CDC). In order to achieve a target lateral vehicle response, an integrated AFS and four individual wheel braking controls have been used for an optimum distribution of longitudinal and lateral tyre forces the desired yaw moment for lateral stability has been designed by the sliding control method using a planar bicycle model and taking into consideration cornering stiffness uncertainties. The desired yaw moment is generated by the coordinated control of AFS and ESC. Optimal coordination of the control authority for the AFS and the ESC has been determined to minimise longitudinal deceleration. Estimated vertical tyre forces have been used for the optimum distribution of the longitudinal and lateral tyre forces. For the improved performance of the lateral stability control system, the damping forces at the four corners have been controlled to minimise roll angle by the CDC system. The response of the vehicle to the UCC system has been evaluated via computer simulations using vehicle dynamic software CarSim and a UCC controller coded with Matlab/Simulink. Computer simulations of a closed-loop driver–vehicle–controller system subjected to double lane change have been carried out to prove the improved performance of the proposed UCC strategy over a conventional ESC.

Estimation of Tire Forces for Application to Vehicle Stability Control

Estimated tire forces can be used to implement unified-chassis-control (UCC) systems. This paper presents a scheme for longitudinal/lateral tire-force estimation. The longitudinal and lateral tire-force-estimation scheme has been designed, and this consists of the following five steps: vertical tire-force estimation, shaft torque estimation, longitudinal tire-force estimation based on a simplified wheel-dynamics model, lateral tire-force estimation based on a planar model, and the combined tire-force estimation. The combined tire-force-estimation scheme has been designed to compensate for the longitudinal/lateral tire-force estimator, which uses a random-walk Kalman filter. The proposed estimation scheme has been integrated into a UCC system. The performance of the UCC system, including the estimator, has been evaluated via computer simulations conducted using the vehicle dynamic software CARSIM, the ASM vehicle model, and the UCC system coded with Matlab/Simulink.

Design of a rollover index-based vehicle stability control scheme

This paper presents a rollover index (RI)-based vehicle stability control (VSC) scheme. A rollover index, which indicates an impending rollover, is developed by a roll dynamics phase plane analysis. A model-based roll estimator is designed to estimate the roll angle and roll rate of the vehicle body with lateral acceleration, yaw rate, steering angle and vehicle velocity measurements. The rollover index is computed using an estimated roll angle, estimated roll rate, measured lateral acceleration and time-to-wheel lift. A differential braking control law is designed using a direct yaw control method. The VSC threshold is determined from the rollover index. The effectiveness of the RI, the performance of the estimator and the control scheme are investigated via simulations using a validated vehicle simulator. It is shown that the proposed RI can be a good measure of the danger of rollover and the proposed RI-based VSC scheme can reduce the risk of a rollover.

Unified Chassis Control for Rollover Prevention and Lateral Stability

This paper describes a unified chassis control (UCC) strategy to prevent vehicle rollover and improve vehicle lateral stability. A rollover index (RI), which indicates impending rollover, and a model-based roll state estimator are introduced to detect potential rollover. An RI/lateral stability-based rollover mitigation (ROM) controller is designed to reduce the danger of rollover without loss of vehicle lateral stability by integrating electronic stability control (ESC) and continuous damping control (CDC). Simulation results indicate that significant improvement in vehicle rollover prevention and lateral stability can be expected from the proposed UCC system.

Design of an unified chassis controller for rollover prevention, manoeuvrability and lateral stability

This paper describes a unified chassis control (UCC) strategy to prevent vehicle rollover and improve both manoeuvrability and lateral stability. Since previous researches on rollover prevention are only focused on the reduction of lateral acceleration, the manoeuvrability and lateral stability cannot be guaranteed. For this reason, it is necessary to design a UCC controller to prevent rollover and improve lateral stability by integrating electronic stability control, active front steering and continuous damping control. This integration is performed through switching among several control modes and a simulation is performed to validate the proposed method. Simulation results indicate that a significant improvement in rollover prevention, manoeuvrability and lateral stability can be expected from the proposed UCC system.

Model-based Estimation of Vehicle Roll State for Detection of Impending Vehicle Rollover

This paper describes a new methodology for designing model-based estimators for detection of impending vehicle rollover. Vehicle roll motions are induced by maneuvering and road disturbances. An estimator is designed based on a three-degrees-of freedom vehicle maneuvering model and a four-degrees-of freedom half-car suspension model to obtain good estimates of the vehicle roll angle and roll rate in driving situations in which both maneuvering and road disturbances affect the vehicle roll motions. The estimator uses already existing sensors, such as steering wheel angle sensor, lateral acceleration sensor, and yaw rate sensor, on a vehicle equipped with an electronic stability control (ESC) system. Since road disturbance is unknown or very expensive to measure, disturbance-decoupled-observer design technique is used in the design of the estimator. The performance of the estimator is evaluated through computer simulations using a validated vehicle simulator. It is shown that, only with already available sensor measurements, good estimates of the roll angle and roll rate can be obtained using the proposed estimator in driving situations in which both maneuvering and road disturbances affect the vehicle roll motions. A rollover index that indicates rollover danger has been computed using the measured lateral acceleration and yaw rate, and estimated roll angle and roll rate. The rollover index computed using the estimated states is shown to be a good measure for the danger of vehicle rollover.

Coordinated implementation and processing of a unified chassis control algorithm with multi-central processing unit

Abstract This paper proposes a multi-core architecture for implementation of a unified chassis control (UCC) algorithm on a field programmable gate array (FPGA) which operates as a multi-core process. The proposed multi-core architecture aims to reduce the operating load and maximize the reliability for improving the performance of the UCC system. The proposed multi-core architecture supports distributed control with analytical and physical redundancy capabilities. The UCC algorithm used in this research consists of three parts: a supervisor, a main controller, and fault detection/isolation/tolerance control (FDI/FTC). These three components are implemented and evaluated with the multi-core process environment with the FPGA. An electronic control unit is configured by three MicroBlaze processors with FPGA, and a control area network (CAN) is also implemented for hardware-in-the-loop (HILS) evaluation. Three types of multi-core architectures, i.e. distributed processing, triple voting, and hybrid operation, are implemented to investigate the performance and reliability. A vehicle simulator and brake HILS are used to evaluate the proposed multi-core architectures. From the test results, it is shown that all of the proposed multi-core systems have better performance and improved reliability compared with the single core system. In particular, the hybrid operation architecture shows better reliability and performance compared with the other two multi-core architectures, distributed processing and triple voting.

Unified Chassis Control for Vehicle Rollover Prevention

This paper describes an unified chassis control (UCC) strategy to prevent vehicle rollover and improve maneuverability. In order to detect a danger of rollover, rollover index (RI) which indicates an impending rollover is determined. The rollover index is calculated using estimated roll angle, roll rate and measured lateral acceleration. Lateral and vertical model-based roll state estimators are designed and combined to obtain the vehicle roll state induced by maneuvering and road disturbances. The vehicle mass is adapted to improve the robustness of the roll state estimator. The RI-based rollover mitigation controller (RMC) is designed by integrating the electronic stability control (ESC), active front steering (AFS) and continuous damping control (CDC). The RI/lateral stability-based RMC is also designed to ensure maneuverability. Computer simulation is conducted to evaluate the proposed UCC scheme by using validated vehicle simulation software. From the simulation results, it is shown that the proposed UCC can prevent vehicle rollover and load to improvements in vehicle stability.