Control of a Robotic System Undergoing Transition from Free Motion to Interaction with Soft Tissue

This paper discusses control of a robotic system using the Hunt-Crossley equation as a model for robot-soft tissue interaction to achieve tumor identification and telesurgery. A non-linear model is extended by incorporating realistic assumptions that capture the essential characteristics of soft tissue during its interaction with the slave robot. To ensure accurate position and velocity control, tissue parameters are estimated in real time using adaptive laws. A common Lyapunov function is used to guarantee the stability of the overall system in both contact and non-contact states. The controller explicitly compensates for uncertainties and nonlinearities by adaptively updating control parameters, driving the error signals to zero. Finally, experimental results conducted on a unilateral structure using PHANToM® robots demonstrate the effectiveness of the proposed control strategy.