Direct adaptive control for trajectory tracking of mobile robots

The paper presents a new controller for a two-driving-wheel mobile robot tracking a planned trajectory. The system consists of two control loops, the outer loop is the kinematic control law calculating the required right and left wheel angular velocities to follow the planned trajectory, and the inner loop is the dynamic control law calculating the torques to drive the wheels to obtain the demanded angular velocity. To deal with the uncertain mobile robot parameters, the dynamic controller is designed using a MIMO direct adaptive control scheme. Radial basis function (RBF) networks are used to approximate the dynamic feedback linearization control law. A sliding control term is used to ensure the stability in the presence of approximation error. The stability of control system is proven thank to Lyapunov theory. Simulation results highlight the performances of the designed controllers in trajectory tracking under test scenarios with time-varying robot parameters and external disturbances.