Stability experiment of a biped walking robot with inverted pendulum

Abstract

This paper is concerned with a balancing motion formulation and control of the ZMP (zero moment point) for a biped walking robot that has a balancing weight of an inverted pendulum. The original dynamic stability equation of a walking robot is nonlinear; because it's balancing weight is an inverted pendulum type. The stabilization equation of a biped walking robot is modeled as a linearized non-homogeneous second order differential equation with boundary conditions. With the FDM (finite difference method) solution of the linearized differential equation, a trajectory of balancing weight can be directly calculated. Furthermore, it makes that possible input the desired ZMP or ZMP trajectory for various gait, situation and complex motion. Also, it can be easily approximated that a balancing range or motion when some link parameters are changed; especially a balancing mass is changed. In this paper, the simulator with a balancing weight of an inverted pendulum is programmed to get and calculate the desired ZMP and the actual ZMP. The operating program is developed for a real biped walking robot IWRIII-IP. Walking of 6 steps will be simulated and experimented with a real biped walking robot. This balancing system will be applied to a biped humanoid robot, which consist legs and upper body, at future work.