Inverse dynamics and feet-terrain collision model for optimal distribution of the contact forces during crab motion of a hexapod robot

Abstract

The present study deals with the kinematics, dynamics and feet-ground contact modeling of a hexapedal robotic system. Feet-ground interaction generates contact forces, which play a very important role for locomotion on varying terrains. In this study, the constrained inverse dynamical model is formulated as a coupled dynamics problem using Newton-Euler approach with implicit constraints in Cartesian coordinates. The contact force distribution in the feet during interaction with the terrain is considered to be a constrained optimization problem. For a more realistic locomotion analysis, impact of feet-tip with the terrain is considered, which is assumed to be governed by a compliant normal contact force model. The paper also investigates the optimal feet forces’ distributions under body forces, total power consumption etc. without any external disturbance during the robot’s locomotion with wave-crab gait (duty factor = ½).