柔性关节机械臂接触力阻抗控制系统设计

Design of Contact Force Impedance Control System for Flexible Joint Robot Arm

摘要:

由于机械臂关节具备柔性特性,接触力情况复杂多变,且系统存在非线性阻抗因素,传统的单一力信号跟踪控制方式过于僵化,难以适应复杂多变的接触力环境,导致控制效果不佳。为此,设计柔性关节机械臂接触力阻抗控制系统。设计机械臂伺服控制器时,采用动态阻抗参数和接触力位置控制策略,结合非线性阻抗模型和双环控制架构,实现柔顺交互。末端关节轨迹生成器通过直线型规划程序封装为Simulink模块满足柔顺性和动力学优化,确保精准控制。基于磁感应的力矩传感器实时测量末端力/力矩,支持精细操作。利用拉格朗日方程分解接触力并补偿柔性变形,分析应力分布和阻抗影响,动态调节参数。引入粒子群优化算法优化力控性能,平衡接触力与位置。通过跟踪力信号、抑制扰动内环和修正力强度外环的双环阻抗控制,缓冲外力冲击,保证轨迹精度,最终实现高精度力/位置跟踪控制。实验结果表明,应用上述系统可以较好平衡X轴、Y轴方向上关节受力点的位置误差,从而避免机械臂接触力载荷出现明显波动的数值变化情况,控制效果较好。

Abstract:

Due to the flexible nature of robotic arm joints, the contact force situation is complex and variable, and there are nonlinear impedance factors in the system. The traditional single force signal tracking control method is too rigid and difficult to adapt to the complex and variable contact force environment, resulting in poor control effect. Therefore, a flexible joint robotic arm contact force impedance control system is designed. When designing a servo controller for a robotic arm, dynamic impedance parameters and contact force position control strategies are used, combined with a nonlinear impedance model and a dual loop control architecture to achieve compliant interaction. The end joint trajectory generator is encapsulated as a Simulink module through a linear planning program to meet the requirements of flexibility and dynamic optimization, ensuring precise control. Real time measurement of end force/torque using magnetic induction based torque sensor, supporting fine operation. Decompose contact force and compensate for flexible deformation using Lagrange equation, analyze stress distribution and impedance effects, and dynamically adjust parameters. Introducing particle swarm optimization algorithm to optimize force control performance and balance contact force and position. By tracking the force signal, suppressing the disturbance inner loop, and correcting the force intensity outer loop through dual loop impedance control, external force impact is buffered to ensure trajectory accuracy, ultimately achieving high-precision force/position tracking control. The experimental results show that the application of the above system can effectively balance the position errors of joint force points in the X-axis and Y-axis directions, thereby avoiding significant fluctuations in the numerical changes of the contact force load of the robotic arm, and achieving good control effect.