Hierarchical Control of Nonlinear Active Four-Wheel-Steering Vehicles

Abstract

A new type of hierarchical control is proposed for a four-wheel-steering (4WS) vehicle, in which both the sideslip angle and yaw rate feedback are used, and the saturation of the control variables (i.e., the front and rear steering angles) is considered. The nonlinear three degrees of freedom (3DOF) 4WS vehicle model is employed to describe the uncertainties originating from the operating situations. Further, a normal front-wheel-steering (2WS) vehicle with a drop filter of the sideslip angle is selected as the reference model. The inputs for the rear and front steering angles of the linear 2DOF 4WS, required to achieve the performances described by the reference model, are obtained and controlled by the upper controller. Further, the lower controller is designed to eliminate the state error between the linear 2DOF and nonlinear 3DOF 4WS vehicle models. The simulation results of several vehicle models with/without the controller are presented, and the robustness of the hierarchical control system is analyzed. The simulation results indicate that using the proposed hierarchical controller yields the same performance between the nonlinear 4WS vehicle and the reference model, in addition to exhibiting good robustness.

High-speed lateral stability and trajectory tracking performance for a tractor-semitrailer with active trailer steering

“…Therefore, to improve the lateral stability of the tractor-semitrailer and the trajectory tracking performance of the trailer, the lateral acceleration and sideslip angle at the trailer's CG are taken as the optimization objectives in this study. The relationship among the trailer's lateral acceleration, the trailer's sideslip angle, and the active steering angle is created by forming a general cost function given in Eq (14).…”

“…Existing methods for improving vehicles' lateral stability or the trajectory tracking performance mainly include the active suspension method [4][5][6], the compliance steering or passive steering of the rear axles or wheels [7][8][9], the differential braking method [10,11], the active steering of the rear axles or wheels [12][13][14], and the parameter and state estimation for vehicles [15][16][17]. The active suspension method usually consumes a lot of energy, and the response speed is relatively slow, which is not practical for articulated heavy vehicles (AHVs).…”

Towards Autonomous Driving: Review and Perspectives on Configuration and Control of Four-Wheel Independent Drive/Steering Electric Vehicles

“…In [117], the fuzzy SMC approach is applied to the vehicle dynamic control of 4WS vehicles, which can enhance the dynamic response and deal with system nonlinearity. As Figure 10 shows, in [118], a new type of hierarchical control is proposed for 4WS vehicles, which uses the fractional SMC to obtain good robustness. Although SMC shows good performance in terms of dealing with system nonlinearity, controller chattering is still a critical issue for application.…”

Towards Active Safety Driving: Controller Design of an Active Rear Steering System for Intelligent Vehicles

“…To address the above issue, a nonlinear triple-step steering controller is designed for the ARS system, which can improve handling stability even if the tire works in an extremely nonlinear region [16]. Based on the nonlinear three degrees of freedom (DoF) four-wheel steering (4WS) vehicle model, a hierarchical control framework is designed for the ARS system, which shows good robustness to address nonlinear disturbances [17]. In [18], a virtual mass-spring-damper system is applied to the ARS controller design, which can deal with the parametric uncertainties.…”