Motion control of human bipedal model in sagittal plane

Abstract

This paper discusses the construction of a mathematical model for a planar seven-link bipedal model which is comprised of an upper body and two legs (thigh, shank and feet in every leg) in the sagittal plane. Procedures of kinematic model and dynamic model constructions are presented in this paper. The mathematical model for dynamic equations of motion based on the absolute angle is obtained using Lagrange’s equations. Then, a dimension transformation of mathematical model into relative angles was performed. New inertia matrix of the transformed equations was verified to be symmetric. Periodic cubic spline is used to obtain smooth walking trajectories of every joint in the biped model. Computed torque controller was applied in the trajectory tracking control of the proposed bipedal robot model. To investigate the performance of motion controller, a simulation study was conducted. The simulation results show that the performance of the purposed motion controller is superior with very minimal tracking error. In future, the controller will be extended and modified with various types of intelligent approaches to give continuous, automatic and online computation of required inertia matrix with certain constraint while the system is in motion.