Abstract: Zero force control is one of the core issues of the collaborative manipulator to realize the drag teaching.At present,the methods are mostly depended on the additional force/torque sensor,which can ensure the measurement accuracy but increase the complexity and cost of the system.A zero-force control method of flexible cooperative manipulator based on joint double position feedback was proposed,which could realize zero-force control of manipulator without external sensors.Based on the flexible characteristics of wave generator and flexible wheel,the dynamic model of harmonic drive joint was established.With the stiffness identification method of harmonic drive joint,a torque estimation method of flexible joint based on double position feedback was established.The simplified gravity torque compensation model was established,and the joint friction torque model was improved by considering the viscous friction and Stribeck Coulomb friction in the process of joint rotation.On this basis,the joint gravity torque and friction torque compensation were realized,and the zero force control of the manipulator was realized.The prototype platform of the harmonic drive integrated joint and the manipulator was built,and the experimental research was carried out.The results showed that the proposed method could effectively realize the zero force control of harmonic drive manipulator without additional force/torque sensor.

Key words: cooperative robot, two-side-position feedback, moment pattern, zero force control, torque compensation

摘要： 零力控制是协作机械臂实现拖动示教的核心问题之一,目前方法多依赖于附加力/力矩传感器,其虽能保证测量精度,但会增加系统复杂程度及成本。提出一种基于关节双位置反馈的柔性协作机械臂零力控制方法,该方法可在无外加传感器条件下实现机械臂零力控制。首先,基于波发生器与柔轮柔性特性,建立了谐波传动关节的动力学模型;其次,基于谐波传动关节刚度辨识方法,建立了基于双位置反馈的柔性关节力矩估测方法;再次,建立了简化重力矩补偿模型,并考虑关节转动过程中的粘滞摩擦和Stribeck库伦摩擦,完善了关节摩擦力矩模型,基于此,实现对关节重力矩和摩擦力矩补偿,实现机械臂零力控制;最后,搭建谐波传动一体化关节和机械臂样机平台,并进行了实验研究,结果表明,所提方法可有效实现无附加力/力矩传感器条件下的谐波传动机械臂零力控制。

关键词: 机械臂, 双位置反馈, 力矩模式, 零力控制, 力矩补偿