Robust precision motion control of a piezoelectric microsurgical manipulator using adaptive non-singular terminal sliding mode

This paper introduces a novel piezoelectric microsurgical manipulator and proposes an Adaptive Non-singular Terminal Sliding Mode Controller (ANTSMC) integrated with Time Delay Estimation (TDE) to address displacement errors induced by nonlinearity, time-varying parameters, and system uncertainties inherent in the piezoelectric screw-driven mechanism at the microscale. Through the Non-singular Terminal Sliding Mode Control (NTSMC), the chattering and singularity issues associated with conventional terminal sliding mode control are circumvented, and the system states are driven to equilibrium within a finite convergence time. Time Delay Estimation techniques are employed to estimate and counteract unknown aggregated disturbances in real-time, thereby obviating the necessity for a precise system model. Furthermore, an adaptive gain mechanism continually updates the controller's gain based on the current system state and disturbance levels, thus strengthening resilience to modeling uncertainties. The proposed control system's stability is validated through Lyapunov stability analysis. A high-precision biological cell microsurgery platform was constructed by integrating the manipulator, a biological microscope, and the control system. Experimental results demonstrate that the manipulator exhibits multi-scale kinematic characteristics, micrometer-level resolution, and a 26 mm working stroke. The proposed ANTSMC-TDE controller achieves a root mean square tracking error (RMSE) of 2.79 μm in hardware experiments.