Flexible foot system for a biped robot

Abstract

Biped Robots are a class of legged robots, which should work in various environments such as flat or uneven terrain. To walk on different surfaces, it should be adaptable to the variations on the ground with a flexibility in foot movement to maintain its stability. Zero Moment Point (ZMP) is a technique used to ensure dynamic stability. ZMP should be within the support polygon for a robot to be stable. In this paper, a 13 degree of freedom (DOF) biped robot with a special foot mechanism to walk on an uneven terrain is designed. Reference trajectory is developed for all joint angles from the ZMP reference using inverse kinematics. Computed Torque Controller is implemented to follow the reference trajectory. Force sensors are mounted on the foot to check whether the foot has made contact with the ground. When the foot is in contact with the ground, actual ZMP is calculated to check the stability. It is observed that the actual joint trajectories follow the stable reference trajectories, thus the effectiveness of the controller is validated. Simulation is carried out in MATLAB platform.