Nonlinear Control of a Robot-Trailer System Using a Hybrid Backstepping-linearizing Approach

Abstract

In this work, the author develops a nonlinear controller to stabilize an autonomous wheeled robot and trailer system. A dynamic model based on robot-trailer kinematics that has previously proven sufficient for state feedback control is chosen for the ease of design. An iterative approach similar to backstepping is utilized to obtain the control input. In a manner reminiscent of feedback linearization, nonlinearities are cancelled at each step to obtain an equivalent linear system. This method is significantly different from integrator backstepping method as no signal differentiation is required. However, it is also different from the feedback linearization method as it does not require any coordinate transformation. This hybrid method is essentially a selective amalgamation of the two methods. In contrast to known state-of-the-art approaches, the proposed method stabilizes the system in both the forward and reverse motion directions, without modeling modifications. Simulation results suggest that the Hybrid Backstepping Controller(HBC)is sufficient for regulating the trailer to the desired path from any initial condition. Experimental results confirm that the Hybrid Backstepping Controller(HBC) can control the robot-trailer system and can regulate the trailer over a typical geophysical surveying path.