Fuzzy adaptive recursive terminal sliding mode control for an agricultural omnidirectional mobile robot

Nowadays, agricultural robots play a vital role in the development of agriculture. This paper proposes a fuzzy adaptive recursive terminal sliding mode control strategy for a Mecanum-wheeled omnidirectional mobile robot to fulfill trajectory-tracking tasks in transporting agricultural products. First, a kinematic-and-dynamic model with four control inputs and three states is established for the mobile robot. Then, a fuzzy adaptive recursive terminal sliding mode controller is designed, and the control system’s stability is assured via detailed mathematical proof. Subsequently, a dead-reckoning scheme based on the Runge–Kutta formula is presented to reckon the robot’s position-and-posture information online. A conventional sliding mode controller and a nonsingular terminal sliding mode controller are designed for comparison. Lastly, experiments in two scenarios of circular and figure-eight trajectories with different loads are carried out. The experimental results reveal the superiority of the proposed control strategy compared with the benchmark controllers.