Adaptive tracking of orthopedic force for bone external fixation robot based on impedance control

To address the problem that the orthopedic force of the traditional bone external fixator cannot be accurately controlled and has poor safety, the article establishes a knee bone external fixation robot based on the RCM configuration and proposes an orthopedic force tracking control method with indirect adaptive impedance. Due to the existence of mechanical friction and external uncertainty, to address the problem of poor robustness of impedance control, the force error signal is adopted as the driving force of the target impedance, a new impedance model is formulated to adapt to the changes in the orthopedic environment. According to the changes in the contact force, the adaptive law is designed to regulate the impedance parameters in real time, which compensates for the uncertainty of the environmental dynamics on the line. Therefore, the system′s force tracking error is zero. Comparative simulations and prototype experiments of the proposed control algorithm for tibial orthopedic force control are implemented. The results show that the impedance control simulation results of the weighted average of the performance indicators are 2. 12, 8. 58 and 13. 2, and the maximum error of the force tracking experiment is 20 N. Compared with impedance control, the weighted average of the performance indicators of adaptive impedance control simulation is only 0. 36, 0. 18 and 0. 61, and the force tracking fluctuation error is controlled to be within ±3N, which has better robust and adaptive ability. © 2023 Science Press. All rights reserved.