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.

The time-domain passivity approach has been proposed in the literature in a variety of formats to guarantee the stability of teleoperation leader-follower systems. The conventional use of the proposed technique utilizes the control effort at the follower side as the force feedback to be sent back to the user at the leader’s side. However, this has resulted in transparency problems, especially when the follower dynamics are not negligible. On the other hand, four-channel and three-channel Lawrence architectures have been investigated widely in the literature to maximize the transparency of the system when, in most advanced cases, stability is guaranteed using wave-variables. However, wave-variables are historically known for their transparency deterioration problems. In this paper, we propose a two-layer approach taking advantage of the fusion of (a) a more optimal derivation of Lawrence telerobotic architecture (utilizing only two channels), and (b) a two-port time-domain passivity stabilizer while comparing the performance with a one-port passivity stabilizer. The two-channel derivation of the Lawrence architecture allows for implementing a two-port time domain passivity approach, which is investigated in this paper. The performance of this is compared systematically through a multi-objective approach by analyzing dissipated energy besides force and velocity errors for a wide range of time delays and frequencies of excitation. The paper gives a comprehensive view of the efficacy of two-port versus one-port time-domain passivity control when combined with the two-channel derivation of Lawrence architecture.