Balancing control of mobile manipulator with sliding mode controller

This paper proposes an attitude control system to keep the balance of a two-wheeled mobile manipulator which consists of a mobile platform and a three D.O.F. manipulator. In the conventional control scheme, complicated dynamics is utilized for balancing control of a mobile manipulator. In this paper, however, three links are considered as one body and the dynamics is derived easily by using inverted pendulum model. Sliding mode controller is characterized as low sensitivity to plant parameter uncertainties and disturbances and non-necessity of an explicit model of the system. Therefore, it is adopted in this research for the attitude control of mobile platform with respect to the pitch axis. The center of gravity for the whole mobile manipulator is changing along with the motion of the manipulator. And the orientation variation of center of gravity is used as reference input for the sliding mode controller to maintain the center of gravity in the middle of robot so that the whole system can keep balance. To confirm the performance of the controller proposed in this paper, MATLAB Simulink has been used and an experiment is carried out to demonstrate the superiority of the proposed attitude control.