Steering angle saturation analysis in PGR under feedback gain switching strategy for car-like robots

Abstract

This work analyzes the influence of steering angle saturation to the convergent property in the Path-generating Regulator (PGR) under the feedback gain switching strategy for car-like robots. The PGR control method carries out asymptotic convergence to a given path function group. It has been extended to car-like robots, and its convergent region has been expanded by the feedback gain switching strategy. However, under this strategy, when the robot restarts after the feedback gain switches, the command of the steering angle tends to be close to ±π/2 rad, which might exceed the maximum steering angle. This phenomenon causes steering angle saturation. The robot then drives along the minimum turning circle. In this paper, the convergent property of the robot under steering angle saturation is investigated first. Results show that the convergent property is related strongly to the number of singular points, which depends on the center location of the minimum turning circle. Then the convergent properties at different locations are clarified through region division. Moreover, an extended feedback gain switching strategy method is proposed to change the convergent property in the specific region. Based on simulation and experiment results, we summarize the convergent property related to the region and verify the proposed method.