Power-Based Velocity-Domain Variable Structure Passivity Signature Control for Physical Human-(Tele)Robot Interaction

The excess of passivity (EoP) of the human biomechanics plays an imperative role in absorbing the interaction energy during physical human-(tele)robot interaction and can be exploited by controllers used for stabilization of human-centered (tele)robotic systems. However, the first generation of nonlinear EoP-based stabilizers loaded the force reflection channel resulting in degradation of the force profile. This will challenge applications that are heavily dependent on the quality of force reflection, such as telerobotic rehabilitation. This article explores the possibility of developing a nonlinear stabilizer that modifies the reflected velocity to the follower-side operator based on the corresponding EoP map. As an applied benefit in the context of telerehabilitation, the proposed stabilizer does not require information about the EoP of all patients; instead, it would require that for the individual therapist who works with the group of patients. The article provides the mathematical derivation and stability proof of the nonlinear design of the stabilizer named 'power-based velocity-domain variable structure passivity signature control (PV-VSPSC).' The proposed nonlinear stabilizer is evaluated through systematic experiments and systematic grid simulation studies in this paper.