Adaptive estimation of robot environmental force interacting with soft tissues

In this paper, position control of a robot´s end effector, by proposing an estimation mechanism for the interaction force between robotic tools and a soft tissue is presented. The proposed approach is using an adaptive strategy to provide the estimated force for achieving convergence of position and velocity tracking errors to zero. Moreover, the global stability of the closed loop system, using a time varying Lyapunov function and Barbalat´s lemma is investigated. The proposed scheme considers a dynamic model for the environment. For this purpose, a viscoelastic model is adopted for the environment rather than an elastic one. This assumption has a great impact on effectiveness of all control strategies that use the force feedback, when working with soft tissues. Moreover, simulation results are given to demonstrate the effectiveness of the proposed approach.