Estimation and verification of the trajectory forms generated by a legged sliding robot

This paper presents an 3D algorithm to estimate the motion trajectory of a four legged sliding robot considering the ground friction coefficient and the payload distribution at leg ends during walk on a flat ground including ascending or descending slopes. We formulate mathematical expression for estimating energy cost of motion utilizing the principle of virtual work under the condition where the robot moves by alternating pivotal feet having hemispherical form at their ends. Then we minimize the sum of the virtual work for determining actual robot motion. Results of the minimization make it possible to simulate the motion behaviors for visualizing robot trajectory in different traveling environments. Additionally, we verify simulation results by demonstrating the walk with functions of turn and spin as a legged type of the hybrid robot PEOPLER-II. Hence the proposed algorithm is useful for clarifying the robot motion behaviors.