基于辅助约束与变阶分数阶导纳的医疗串联机械臂柔顺交互控制

Compliant interaction control method for medical serial manipulator based on auxiliary constraints and fractional admittance control

摘要:

针对医疗串联机械臂在狭窄敏感空间接触任务中安全边界受限、接触力波动及柔顺性不足等问题,提出融合辅助约束、变阶分数阶导纳和控制障碍函数安全滤波的柔顺交互控制方法。首先,依据医学影像或任务规划构建风险区域、安全通道和关键连杆监测点约束,并以符号距离场表征安全裕度；其次,根据接触刚度和力变化率估计接触状态,在线调节导纳阶次,生成法向位姿修正；最后,采用CBF-QP最小修正名义运动,统一约束几何边界、接触力和关节平滑性。半实物实验表明,在曲面边缘划动中,所提方法的平均轨迹误差为0.23 mm、力RMSE为0.71 N、最大力超调为8.59%,较固定阶次导纳控制和变阶导纳控制表现出更优的轨迹精度和接触力稳定性。

Abstract:

To address safety-boundary limitations, contact-force fluctuations, and insufficient compliance of medical serial manipulators during contact tasks in narrow and sensitive spaces, a compliant interaction control method integrating auxiliary constraints, variable-order fractional admittance control, and control barrier function safety filtering is proposed. First, constraints for risk regions, safe channels, and monitoring points on critical links are constructed from medical images or task planning, and a signed distance field is employed to quantify safety margins. Second, the contact state is estimated using local contact stiffness and force variation, and the admittance orders are adjusted online to generate normal-direction position corrections. Finally, a control barrier function-based quadratic programming (CBF-QP) filter minimally modifies the nominal motion while jointly enforcing geometric boundaries, contact-force limits, and joint-motion smoothness. Semi-physical experiments show that, in a curved-edge sliding task, the proposed method achieves a mean trajectory-tracking error of 0.23 mm, a force RMSE of 0.71 N, and a maximum force overshoot of 8.59%. Compared with conventional auxiliary-constrained admittance control, the proposed method provides improved tracking accuracy and contact-force stability.