A passive walking strategy for a biped robot with a large mass torso by a spring and a damper

This paper presents a control system for a biped robot with a large mass torso by extension of previous work in the field of CPG (Central Pattern Generator). The algorithm takes advantage of the passive dynamics of walking, assisting only when necessary with an intermittent oscillator driving the hip joint. However, a biped robot with a large mass torso cannot walk stably only by the CPG controller and a simple feedback control. We speculate about inherent reasons of falling based on dynamics principles and propose a method to solve this problem. This proposed method is that each leg of the model is connected to a torso by a virtual spring. Furthermore a virtual damper with the variable damper coefficient is attached between a torso and a stance leg. It makes the horizontal moving of the torso easy by shortening the step length and swinging the torso. The results from simulation indicate our controller has a good effect on the biped robot walking with a large mass torso.