TRAJECTORY ANALYSIS OF AN INDEPENDENTLY DRIVEN WHEELED ROBOT AND IT'S EXPERIMENTAL VERIFICATION

This paper analyses sliding motion of a wheeled robot driven by independently controlled wheels during roll on a flat ground including ascending or descending. We formulate mathematical expression for estimating energy cost of motion utilizing the principle of virtual work under such the condition that the robot moves with a fixed arrangement of wheel axes without using a steering handle. Obviously, friction coefficient and payload distribution on the ground are dominant to the behaviors of wheel sliding. We minimize the sum of the virtual work for determining actual robot motion. Results of the minimization make it possible to simulate the sliding behaviors for visualizing trajectories in different ground conditions. Our hybrid robot PEOPLER-II demonstrates the rolling with functions of turn or spin as a wheeled robot by using angular velocity control rules used in the simulation. Experimental data show that the proposed mathematical formulation and its minimization method are valid for clarifying wheeled sliding motion behaviors. The method is widely applicable to wheeled robots driving each wheel with independent angular velocity.