Energy preserving control of a hopping robot based on hybrid port-controlled Hamiltonian modeling

In this paper, we propose an energy-based approach to feedback control problem for a hopping robot on an elastic ground. In order that the system behaves in a periodic hopping motion, we make an attempt to keep the system's total energy (Hamiltonian) to a certain specified value. Since our target is inherently a hybrid system that has discontinuous and discrete event dynamics, we suggest a suitable impact model and describe it as a hybrid version of port-controlled Hamiltonian system. Then a passivity based control called IDA (interconnection and damping assignment) is applied to this problem, which results in a good performance in the ideal situation. Moreover, we introduce a servo-like integrator into this controller to reject disturbances due to modeling uncertainty. Efficiency of the proposed method is validated both in simulations and experiments using our newly developed hopping robot system.