An Acupuncture Robot Integrating Needle Bending Compensation and Manipulative Techniques: Modeling, Control, and Validation

In light of the shortage of acupuncturists and issues such as subjectivity leading to inconsistent efficacy and variability in accuracy and stability, an eight-degree-of-freedom (DOF) dexterous acupuncture robot system is developed in this article. An effective model predictive control (MPC) scheme, integrating needle bending compensation and manipulative techniques, is proposed to ensure the safety, accuracy, and stability of acupuncture manipulative trajectory tracking control. Based on acupuncture’s working scenarios, a dexterous 2-DOF acupuncture mechanism is designed. Then, the kinematic and acupoint models are established. To enhance the controller’s robustness, trajectory tracking constraints are included as soft constraints in the objective function before needle insertion, leading to the development of a trajectory-constrained MPC (TCMPC) model. This model not only improves the tracking accuracy and convergence speed but also ensures the stability of the solution. Additionally, a needle bending correction trajectory control method, considering needle deformation, is derived to perceive and correct the needle bending deformation under complex force environments. Furthermore, an adaptive impedance control method, integrating feedforward-feedback control (FFC), is proposed to simultaneously control force and track manipulative techniques under various contact environments. The uniform ultimate boundedness of the closed-loop system is verified using the Lyapunov theory. Finally, the effectiveness of the proposed methods and prototypes is validated through numerical simulations and practical experiments.