Underactuated control of a bionic-ape robot based on the energy pumping method and big damping condition turn-back angle feedback

This paper studies a reliable control strategy for a bionic-ape brachiation robot with dual-arm hands, a four-link brachiate mechanism, which swings and grasps branches like a gibbon. Based on the analysis of the brachiation of gibbons and humans, the big damping nonholonomic constraints model is introduced. A control strategy which combines the energy pumping control with the big damping turn-back angle feedback control is proposed. The grasping motion was divided into several processes: the swing-up self-starting phase, the energy rising phase, the transition phase and the grasping phase. A self-starting controller is designed for swing-up motion from a downward stable position. In the energy rising phase, an energy pumping control law is deduced based on Lyapunov stability theory, and the singularity and convergence of the system are analyzed. The system energy is calculated periodically to determine if the robot gets enough energy for grasping, so that it could shift into the transition phase. A position–orientation control method is adopted to realize that the gripper grasps target bars in the desired position, orientation and speed. By means of ADAMS-MATLAB co-simulation, the bionic-ape robot achieves smooth swing-grasp motions under different heights and horizontal distances. The simulation results indicate that this method has advantages of universality and reliability in a grasping target bar. Therefore, the effectiveness of the proposed control strategy is validated.