A Finite State Machine and Walking Control Algorithm of the Biped Robot with Flat Foot

Abstract

This paper presents the control strategy for 7-link biped consisting of an underactuated floating trunk, rigid legs, and flat feet. This proposed control enables a biped to perform stable walking without using any pre-designed trajectories. We consider the force direction control in Biped Trunk Spring Loaded Inverted Pendulum (BTSLIP) from our previous study, which shows the stable behavior in walking motion. Then, we aim to inherit the advantage of force direction control related to the BTSLIP. Herein, we add two virtual springs from hip to each foot then map simple virtual model to the real robot joints torque. Furthermore, the control of ankles will adapt with different walking phase by following finite state machine. The dynamical simulation under random initial state validates the stabilizing the floating trunk and maintaining of the robot model equipped with the proposed controller.