Bilateral Teleoperation: Quantifying the Requirements for and Restrictions of Ideal Transparency

The well-known tradeoff between transparency and stability challenges the realization of bilateral teleoperation systems. Ideal conditions for the four-channel framework have been presented, but the practical feasibility is hardly quantified. This brief bridges the gap between existing detailed analysis of basic two-channel controllers and the ideal conditions for the four-channel framework. Starting from the fundamental stability and transparency limits of the Position-Force controller, two extensions of this controller have been analyzed in detail, using existing metrics for transparency and the absolute stability and bounded environment passivity criterion. This analysis quantitatively describes the effect of hardware properties, modeling errors, and low-pass filters and illustrates as such the restrictions on the realization of ideal transparency. The experimental results, presented in this brief, demonstrate the restricted stiffness transparency of the Position-Force controller, as well as how the extensions provide close to perfect stiffness transparency.