Deriving equations of motion of a wheeled mobile robot and its control using extended multiple impedance strategy

The use of automatic systems for space exploration can dramatically decrease the cost of desired mission. One of the structures that has previously been utilized for space exploration is the wheeled rovers. Wheeled rovers have wide work space and can move with a proper velocity. Their mechanisms are simple and are energy efficient. In the most of the previous studies, it has been assumed that the wheeled robot chassis is rigid. However, if the wheeled robot motion on relatively rough terrain is required then it should be equipped with flexible suspension. Also, in most of the earlier studies, the nonlinear friction between the wheels and ground has not been modeled. Consequently, in this paper, the dynamics equations of a wheeled robotic system with flexible suspension is derived. To model the friction and wheels slip, the Dugoff friction model is utilized. Considering the wheels torque as inputs, a novel two-layer driver is proposed. Adopting the suggested algorithm, the control of pitch angle is possible. In the first layer, the motion of the system is adjusted using modified multiple impedance approach. Also, in the second layer, which is called local controller, the actuating torque of wheels are adjusted so as the output forces/torques of the first layer can be realized. The obtained simulation results support the merits of the proposed new motion strategy control.