Preview Path Tracking Control With Delay Compensation for Autonomous Vehicles

Delay and lag deteriorate path tracking accuracy and system stability. If not properly compensated, they can cause instability or limit the driving speed of autonomous vehicles. This paper presents a preview steering control design considering both communication delay and steering lag to achieve accurate, smooth, and computationally efficient path tracking for highly automated vehicles. Two strategies are adopted for the delay: forward state predictor and delay augmentation. The steering lag is approximated by a first-order lag system. The path tracking problem with delay and lag is solved by the preview control theory. The resulted controller is in an analytical form and is computationally efficient for online implementation. We also analyze the system stability and closed-loop responses in both the time and frequency domain. The control is implemented on an automated vehicle platform and tested inside Mcity and on open roads. Experimental results showed lower tracking errors and significantly improved stability margin compared to the controls ignoring delay and lag.