Effect of Non-passive Operator on Enhanced Wave-Based Teleoperator for Robotic-Assisted Surgery: First Case Study

Minimally invasive surgery (MIS) has been advanced by new medical/surgical robotic technologies, aiming to achieve less invasiveness, smaller or even no scar procedures. Miniaturized surgical robot presents promising alternative to better benefit MIS, but considerable constraints including cables for power and communication may degrade its performance. Wireless communication posses great potential to be utilized, however time delay is inevitably introduced which challenges the design of teleoperation system from both stability and transparency point of view. Wave variable based teleoperation provides stable force reflecting teleoperation with arbitrary time delay, but with both compromised position and force tracking performances. Recently we proposed a wave variable compensated structure to improve the position and tracking performance together with energy reservoir based regulators for stability purpose (Guo et al. In: Proceeding European Control Conference (ECC), Linz, pp. 1980-1985 (2015), [ 23]), but with assumption of passive operator and environment. In this paper, several experiments are conduced to evaluate the passivity of operator using the enhanced wave variable compensated structure, and to study the influence of non-passive behavior conducted by operator to the performance of teleoperation and overall system stability. This first case study shows that non-passive behaviors of operator (such as rigid grasp and trajectory tracking tasks) can inject extra energy into system and may cause stability issues for whole system.