Active Four-wheel Steering Research Articles

Controller Design for Active Four-wheel Steering and Four-wheel Independent Drive-based Mobile Robot: Enhancing Cornering Performance in Negative Phase

Controller Design for Active Four-wheel Steering and Four-wheel Independent Drive-based Mobile Robot: Enhancing Cornering Performance in Negative Phase

Nonlinear Predictive Control of Active Four-wheel Steering Vehicles

Nonlinear Predictive Control of Active Four-wheel Steering Vehicles

Active Obstacle Avoidance Control Strategy Based on Four-Wheel Steering

Active obstacle avoidance control strategy is the main question of intelligent vehicles, and active four-wheel steering is gradually used in the intelligent control system. Considering both tracking performance and driving characters, an active controller with four-wheel steering (4WS) and active rear steering (ARS) based on adaptive model predictive theory (AMPC) is designed. The control architecture is composed a supervisor and an AMPC controller. The supervisor is used to select the appropriate control mode and the AMPC is used to calculate the expected steering angle when the stability indexes over the safety threshold. Finally, the proposed control strategy is simulated via Carsim-Simulink co-simulation. The results show that the integrated controller can track the obstacle avoidance path and has good driving performance.

Game-Based Hierarchical Cooperative Control for Electric Vehicle Lateral Stability via Active Four-Wheel Steering and Direct Yaw-Moment Control

A Stackelberg game-based cooperative control strategy is proposed for enhancing the lateral stability of a four-wheel independently driving electric vehicle (FWID-EV). An upper‒lower double-layer hierarchical control structure is adopted for the design of a stability control strategy. The leader‒follower-based Stackelberg game theory (SGT) is introduced to model the interaction between two unequal active chassis control subsystems in the upper layer. In this model, the direct yaw-moment control (DYC) and the active four-wheel steering (AFWS) are treated as the leader and the follower, respectively, based on their natural characteristics. Then, in order to guarantee the efficiency and convergence of the proposed control strategy, a sequential quadratic programming (SQP) algorithm is employed to solve the task allocation problem among the distributed actuators in the lower layer. Also, a double-mode adaptive weight (DMAW)- adjusting mechanism is designed, considering the negative effect of DYC. The results of cosimulation with CarSim and Matlab/Simulink demonstrate that the proposed control strategy can effectively improve the lateral stability by properly coordinating the actions of AFWS and DYC.

An integrated algorithm for vehicle stability improvement with the coordination of direct yaw moment and four-wheel steering control

This paper presents an integrated algorithm for enhancing vehicle stability with the coordination of four-wheel steering and direct yaw moment control based on a hierarchical control structure. At the upper level of the integrated control system, the desired four-wheel steering angles and yaw moment are derived using a sliding mode control technique; at the lower level, the control inputs are optimised and implemented using a pseudo-inverse method. A 2 degrees of freedom (DOF) vehicle model is generated to design the integrated control algorithm, and an 8-DOF non-linear vehicle model is developed for numerical simulations. The algorithm is evaluated using a hardware-in-the-loop real-time simulation system (HILS) with the physical implementation of active four-wheel steering and differential braking. It is demonstrated that the proposed algorithm can enhance vehicle handling and stability under different operating conditions.

Driving/Braking Force Distribution by Minimax Optimization of Tire Workload (Case of Active Four-Wheel Steering for Zero-Sideslip Control)

The present paper discusses driving/braking force distributions of direct yaw moment control (DYC) to balance tire workloads effectively. The optimum distributions to minimize the maximum workload are derived in the form of simple algebraic expressions. For improvement of vehicle stability and maneuverability, an active four-wheel steering is integrated with DYC by the minimax optimization. The four-wheels are steered by a model following sliding mode controller to maintain zero-sideslip of the vehicle body. Numerical simulations with CarSim, a popular multi-degree-of-freedom vehicle model, are performed to prove effectiveness of the proposed control scheme.

Active Four-Wheel Steering System for Zero Sideslip Angle and Lateral Acceleration Control

This paper proposes an active four-wheel steering system. It has three additional points to an active front steering system proposed by authors: 1) active rear steering to realize zero sideslip angle, 2) variable steering ratio to prevent abrupt involution at slowdown, and 3) model following sliding mode controller to become robust against the system uncertainty. Computer simulations demonstrate good maneuverability of the proposed system.

A new design concept of vehicle dynamics based on active control.

The application of an active control, such as four-wheel steering and active suspension, to cars has changed not only the vehicle dynamics design but also the dynamic characteristics of cars. Active four-wheel steering reduces the sideslip angles of the wheels, thus the unnecessary yawing motion of cars decreases and the time lag in the dynamic response to handling also decreases. An active roll control of the car body makes use of type properties to the best advantage. The four-wheel steering and active suspension upgrade the dynamic performance of cars, and expand the limit performance of dynamics. An adaptive control, integrated control and intelligent control will be introduced to cars, completely changing vehicle dynamics of cars in the near future.