Dynamics Modeling of a Biped Robot with Active Toe Joints

This paper suggests an approach to develop dynamics model and proposes a novel method to solve inverse dynamics of a biped robot with active toe joints. In order to obtain closed-form dynamics model, first, equations of motion are developed for the robot with no interaction. Then, consistent with constraints, unknown forces and moments are considered, using constraints relaxation method. These forces and moments are different during various phases of motion for the robot which is equipped with active toe joints. In our dynamics modeling method, the double support phase is divided into two subphases, depending on the action of toe joint. Then, to compute joints actuating torques and ground reaction forces and moments, inverse dynamics problem for each subphase is solved. The simulation results for walking on flat ground surface illustrate that the proposed approach is effectively used for dynamics modeling of biped robots with redundant legs. Finally, the actual ZMP trajectory is computed using obtained reaction forces and moments to guarantee the feasibility of the generated walking pattern.