Reaction force estimation of surgical robot instrument using perturbation observer with SMCSPO algorithm

This paper proposes a sensorless force estimation method for the end effector tip of a surgical robot instrument. Due to various size and safety constraints related to the surgical robot instrument, it is difficult to measure the reaction force at the instrument tip. This paper presents a method of estimating the reaction force of the surgical robot instrument without sensors and attempts to use state observer of control algorithm. Sliding mode control with sliding perturbation observer (SMCSPO) is used to drive the instrument, where the sliding perturbation observer (SPO) computes the amount of perturbation defined as the combination of the uncertainties and nonlinear terms where the major uncertainties arise from the reaction force. Based on this idea, this paper proposes a method to estimate the reaction force on the end-effector tip of the surgical robot instruments using only SPO and encoder without any additional sensors. To evaluate the validity of this paper, experiment was performed and the results showed that the estimated force computed from SPO is similar to the actual force.