A full-state trajectory tracking controller for tractor-trailer wheeled mobile robots

A tractor-trailer wheeled robot (TTWR) is a kind of wheeled robot which has many applications such as public transportation and conveying various payloads. The considered TTWR in this study includes a differentially-driven tractor towing a trailer. Such a robotic system is nonlinear and underactuated. Also, assuming the nonslip and pure-rolling condition of wheels, TTWR is subjected to nonholonomic constraints. These features make the motion control of the considered TTWR to be a challenging problem. However, up to now, few studies have focused on this problem. For the first time, the various configurations of TTWRs which are resulted by output-oriented trajectory tracking controllers are detailed in this article. Then, a full-state trajectory tracking controller is designed, which not only guarantees the asymptotic stabilization of the output errors but also enables TTWRs to follow the desired paths both in forward and backward movement. To this end, reversibility conditions of the suggested diffeomorphism are obtained and a controller based on coordinate system change is proposed. The response of the suggested kinematic controller is compared with one of the most well-known previous researches to prove the merit of the proposed controller. Finally, the experimental results support the performance of the proposed controller in practice. (C) 2020 Elsevier Ltd. All rights reserved.