Sliding mode control with sliding perturbation observer for surgical robots

Minimally invasive surgery (MIS) robot is made like a long cylinder with small diameter that can fit through a small incision thus decreasing the amount of healthy tissue damaged. Because of the shape of the surgical robot, the cable-driven mechanism is using to the robot. However this is a highly nonlinear system so the performance of the system is not so good. This paper applied a robust motion control algorithm. The algorithm uses partial state feedback for a class of nonlinear systems with modeling uncertainties and external disturbances. The major contribution is the design of a robust observer for the state and the perturbation of the instrument of the surgical robot, which is combined with a variable structure controller (VSC). The combination of controller and observer provides the robust routine called sliding mode control with sliding perturbation observer (SMCSPO). The control performance of the proposed algorithm is evaluated by the simulation and experiment to apply to a two-degree-of-freedom (DOF) robot arm. The results showed high accuracy and good performance.