Transparency Enhancement in Teleoperation

This chapter covers the first component of the overall shared control framework: transparent teleoperation system with large and time-varying delays. First, a non-linear gain for local force feedback control is presented, where this gain is adapted based on the measured forces of the robot. Passivity of this approach is ensured using model-dependent and model-independent methods. Physical behavior of both approaches and their limitations are also presented. The second method uses an explicit force controller to reduce the effects of the limitations identified for the first method. The passivity of the explicit force controller is ensured using time domain passivity approach and the improvements in transparency is validated through hardware experiments. In the final section of this chapter, a new and general method, namely, passive reference coupling (PCR), to ensure stability for any user-defined feedback controller, and which can be used by different research groups working in teleoperation, is proposed.