Dynamical reduction and output-tracking control of the Lunar Exploration Light Rover (LELR)

This paper presents the dynamical reduction and feedback linearization of the Lunar Exploration Light Rover to design an output-tracking torque controller for such a system. The rover is dynamically modeled as a system of rigid bodies that could be considered as a symmetric mechanical system. Its dynamical equations are reduced using the Chaplygin reduction of nonholonomic systems. The reduced dynamical system only involves the rotation and steering angles of the port front wheel. The steering angle and the travelled distance of the vehicle are considered the outputs of the resulting control system. Feedback linearization in the reduced phase space is then employed to derive a proportional-integral-derivative feedback, feedforward torque controller for the rover. Finally, a series of simulation studies are provided to show the robustness of the resulting controller under uncertainties of the dynamical parameters and the disturbance force in the form of friction at the rear wheels.