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基于力传递模型的连续体机器人驱动误差补偿研究

Drive Error Compensation of Continuum Manipulator Based on Force Transfer Model

  • 摘要: 针对绳索传动系统中的非线性摩擦、驱动线伸长及关节间耦合效应导致的连续体机器人控制精度较低的问题,提出了一种考虑非线性摩擦的连续体机器人误差补偿方法。基于虚功原理构建包含关节间耦合作用的连续体机器人静力学模型,分析不同预紧力、不同包角等参数对绳-轮传动系统力传递效率的影响规律,并基于改进的Capstan方程建立包含绳索弯曲刚度及非线性摩擦的力传递模型,提出一种基于力传递模型的驱动误差补偿方法,通过运动实验对所建模型及控制方法进行验证。结果表明,补偿前后连续体机器人运动控制精度得到明显提高,平均位置误差由补偿前5.94 mm降低至补偿后3.15 mm,补偿率达46.97%。

     

    Abstract: Due to the nonlinear friction in wire/cable transmission system, the elongation of the drive cable and the coupling between adjacent joints, the motion control accuracy of the continuum robot is low. So an error compensation method of the continuum robot with considering of the nonlinear friction was presented. Firstly, the kinematics model of the robot was established by the Euler transformation principle under the constant curvature arc assumption, and then the statics model of the continuum manipulator, including the coupling between adjacent joints was derived based on the principle of virtual work. Moreover, the influences of the pre-tightening force of the cable and different wrap angle on the force transfer efficiency of the cable transmission system were analyzed by the experiments. By using the improved Capstan equation, a force transferring model considering the bending stiffness of the cable and the nonlinear friction was established, and the model-based error compensation method was presented. Finally, the effectiveness and correctness of the established model and control method were verified by the motion compensation experiments of the continuum manipulator. The results indicated that the motion control accuracy of the robot after compensation was significantly improved compared with that before compensation, the average position error was reduced from 5.94 mm before compensation to 3.15 mm after compensation, and the compensation rate was up to 46.97%, which verified the correctness of the compensation method and the proposed model.

     

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