Screw Dynamics of a Bipedal Humanoid Robot

The dynamics modeling of bipedal humanoid robots is the foundation of robot torque control. A new dynamics modeling method for a bipedal humanoid robot is demonstrated. First, the dynamics equations of the multi-rigid body system are derived in screw form. The dynamics in screw form is investigated in the theorem of the momentum screw which provides a new dynamics modeling method and reveals the relationship between the momentum screw and the force screw. It brings a new perspective to the research of screw theory. Based on the momentum screw theorem, the dynamic balance conditions for a mechanical system can be obtained. This can provide a reference for the design of dynamic balance controllers. Then, the structure of the bipedal humanoid robot is introduced and the inertia parameters of each rod are calculated. The kinematics of the leg is analyzed. Based on kinematics, the dynamics modeling of the kinematic chain was established. The dynamics for solving the driving torques make the method very suitable for computer programming. Lastly, dynamics simulations of the bipedal humanoid robot have been done to verify the effectiveness of the proposed method in this paper. This methodology provides a new way for the dynamics analysis of complicated spatial manipulators.