Enhancing the Force Transparency of Time Domain Passivity Approach: Prescient Energy Reflection

Abstract

The Time Domain Passivity Approach (TDPA) was developed to guarantee passivity while avoiding conservative constant controller parametrization. For this sake, the TDPA applies adaptive damping to dissipate excessive energy resulting from communication delay in bilateral teleoperation setups. Despite its advantages such as model-independent system observation and control or modularity, the transparency in TDPA is limited by two major artefacts: position drift and jitter in the force feedback signal. While a large variety of extensions have been proposed tackling the first issue, the latter received less attention since its solution is considerably more challenging. Recently, a concept with prescient energy reflection was proposed for the energy reflection-based TDPA (TDPA-ER) which significantly reduced force jitter in passive environments. Prescient energy reflection is feasible in TDPA-ER because the coupling controller is integrated within the passivity-controlled two-port subsystem. In this work, we demonstrate that prescient energy reflection can be applied to TDPA by leveraging the deflection-domain passivity approach. Experimental results with round-trip delays of up to 800 ms validate the potential and robustness of the proposed method considering metrics on force attenuation, perceived stiffness, as well as jitter properties.