An Energy-Based Approach to the Force-Impedance Control Problem for Robot Manipulators

This work proposes a new force-impedance controller design method for robot manipulators in the port-Hamiltonian (PH) framework. Compared with former work in the Euler–Lagrange (EL) framework, fewer control parameters and constraints are needed to achieve asymptotic stability. Besides, a clear physical interpretation can be given due to the PH formalism. First, a canonical transformation is adopted to recast the joint space model into a workspace model. We then achieve impedance control by shaping the inertial and stiffness matrices. Additionally, a change of variable strategy allows an integral force action, such that the force error is included in the system’s passive output. Furthermore, a damping injection is applied to obtain a smoother noncontact-to-contact transition. Finally, we conduct simulations and experiments to compare the advantages of our new force-impedance control law with respect to the EL approaches.