工业机器人的柔性传动部件降低了关节刚度，导致机器人末端存在振动问题。首先对柔性关节控制系统建模，分析其振动特性，并简述关节力矩反馈控制(JTF, Joint Torque Feedback)的抑振原理。由于大部分商用工业机器人无配置关节力矩传感器，且存在重力项力矩和摩擦力矩，故建立柔体动力学方程并给出基于最小二乘法（OLS, Ordinary Least Squares）的参数辨识方法，对重力项力矩和摩擦力矩进行估计，进而提出实时关节力矩估计方法。最后基于六自由度工业机器人搭建实验平台，柔体动力学参数辨识实验结果表明所述动力学模型能准确估计电机力矩，满足反馈控制的应用要求。振动控制实验中，在比例控制下，圆弧和直线振动信号能量最大分别减少达27.61%和26.25%；在比例-微分控制下，最大分别减少达37.56%和41.00%；在改进的“补偿+比例-微分控制”下，最大分别减少达38.32%和45.63%，验证了基于动力学模型的关节力矩反馈振动控制方法的有效性。
Abstract
Flexible transmission components of industrial robots reduce joint’s stiffness, resulting in vibration problem at the end. Firstly, flexible joint control system was modeled, vibration characteristics were analyzed, and vibration suppression principle of joint torque feedback was briefly described. Since most commercial industrial robots aren't equipped with joint torque sensors, and there is gravitational and frictional torque. Secondly, flexible dynamic equations were established and identified method based on ordinary least squares was given, then a real-time joint torque estimation method was proposed. Finally, experiments were conducted on a 6-DOFs industrial robot. Identification experiment of dynamics shows that dynamic model can accurately estimate motor torque, and vibration control experiment shows that under proportional control, arc and linear vibration energy can be reduced by 27.61% and 26.25%, respectively; while under proportional-differential control, reduced by 37.56% and 41.00%, under ‘compensation + PD’ control, reduced by 38.32% and 45.63%. The effectiveness of joint torque control basing robot’s dynamics is verified.
关键词
工业机器人 /
柔性关节 /
柔体动力学 /
关节力矩反馈 /
振动控制
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Key words
industrial robot /
flexible joint /
flexible dynamics /
joint torque
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