Controlling Posture of Jumping Articulated Robot for Stable Landing

Abstract

We propose a new control framework of a jumping articulated robot for a stable landing. We derive dynamics of a hybrid system which consists of a flight phase and a stance phase by connecting them through an inelastic impact model of Formalsky. We assume a flight phase is a nonholonomic Chaplygin system and a stance phase is a fully-actuated system. Based on this dynamics, we propose new time-varying control with considerations for features of jumping such as joint angle limit, short duration of flight. It can make a robot get the desired angle within a specific range at the moment of landing. In addition, we find an optimal control to return a robot to an upright pose based on gain tuning. Simulations using a 4-link robot are also performed to show this visually. The motion from new control framework performs in the limit of joints other and requires less torque than conventional controls without a given trajectory.