Non-singular terminal sliding mode with perturbation viewer for ear surgery robot

This paper investigates the precise motion control of a surgical ear robot (VTA) using a piezoelectric ultrasonic actuator (PUA). The aim is to overcome the challenges of nonlinearity, uncertainties, and disturbances in PUA. For this purpose, a non-singular terminal sliding mode controller is designed along with a disturbance observer. Simulation results show that the designed controller is able to track the desired signal with very high accuracy and in a limited time. The tracking error quickly approaches zero and no chattering is observed in the system response. The performance of the proposed controller is compared with the results of other papers. The results show that the controller proposed in this paper has a lower tracking error than the existing methods. In particular, in the steady state, the tracking error in the proposed method reaches zero, while in the comparative methods, there is an error of several micrometers. The value of the integral absolute error (IAE) for the proposed method (0.0856) is calculated to be lower than that of the methods [41] (0.0996) and [43] (1.3631), which indicates the better performance of the proposed method. Also, the investigations show that the fast terminal sliding mode controller (first design) consumes less energy for tracking than the non-singular terminal sliding mode controller (second design).