Automatic steering control for lanekeeping manoeuvre: outer-loop and inner-loop control design

Abstract

This paper presents a 9-DOF vehicle model combined with a closed-loop driver model for the purpose of studying vehicle lateral control. The performance is evaluated using predefined trajectory of lanekeeping manoeuvre at constant speed. The driver model is developed to control steering angle and uses lookup table path as reference for the control input. The proposed outer-loop control structure of the driver model is a combination of proportional gain control with a yaw effect adaptive fuzzy logic control. The results show that the proposed outer-loop control structure is capable of improving the Y-axis trajectory error and Y-axis trajectory manoeuvres significantly. Stepper motor model, rack and pinion model, and kinematic model of the steering system are integrated to become an inner-loop subsystem for the stepper motor actuated steering (SMAS) system. The performance of the inner-loop control is evaluated using desired trajectories such as square wave, sawtooth wave, and sine wave. The proposed inner-loop control structure consists of closed-loop positioning control for the stepper motor. The results show that the proposed inner-loop control structure is capable of tracking the desired steering angle position and producing the wheel angle needed by the vehicle model.