基于弹性摩擦模型的机器人免力矩传感器拖动示教方法
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国家科技重大专项(2015ZX04005006)和广东省重大科技专项(2014B090921004、2014B090920002)


Dragging Teaching Method without Torque Sensor for Robot Based on Elastic Friction Model
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    摘要:

    基于广义动量的外力观测器和导纳控制方案,采用弹性摩擦模型估计关节摩擦力,并对关节起动阶段的摩擦估计值进行规划,实现了免力矩传感器的机器人拖动示教。基于机器人的动力学模型和运动状态,建立了基于广义动量的机器人外力观测器,观测操作者对机器人施加外力。采用导纳控制方案,根据观测的外力生成关节运动轨迹,实现机器人的拖动示教。采用弹性摩擦模型对关节摩擦进行建模,并在模型中引入Stribeck摩擦项,实现关节在低速和静止状态下的摩擦力估计。为解决关节在静止状态下拖动困难的问题,对关节起动阶段的摩擦力估计进行规划,通过短暂增加关节摩擦的估计值以增加关节驱动力矩,从而实现关节的轻松拖动,且起动规划算法不会对机器人关节的其他运动阶段造成影响。实验表明,〖JP3〗采用本文控制方案可有效实现免力矩传感器的工业机器人拖动示教。采用起动规划方案可有效增加关节起动外力和缩短关节起动时间,在起动阶段关节可以短暂产生26N〖DK〗·m〖JP〗以上的估计力矩,相比未使用规划时关节的起动时间至少可减少70%。同时,关节在起动阶段具有一定的抗干扰能力。

    Abstract:

    Through the external torque observer based on generalized momentum and the admittance control scheme, the robotic dragging teaching without torque sensor was realized, in which the elastic friction model was used to estimate the joint friction torque, and the friction estimation value of the joint starting stage was planned. Based on the dynamics model and motion information of the robot, an external torque observer based on generalized momentum was established to observe the external torque exerted by the operator on the robot. Admittance control scheme was adopted to generate the joint motion trajectory according to the observed external torque, and the dragging teaching robot was realized. The elastic friction model was used to model the friction of the joint, and the Stribeck friction term was introduced into the model to estimate the friction torque of the joint at low speed and static state. In order to solve the difficulty of dragging in the stationary state of joint, the friction estimation of the joint starting stage was planned, and the joint driving torque was also increased temporarily, so as to realize the easy drag of the joint. Meanwhile, the starting planning scheme did not affect other movement stages of the robot joints. Experiment results showed that the control scheme can effectively realize the dragging teaching of industrial robot without torque sensor. At the same time, the starting planning scheme can effectively reduce the external torque and time of joint starting stage. The estimated torque of more than 26N·m was generated in the starting stage. The starting time of the joint can be reduced by 70% compared with the unused starting planning scheme.The joint had a certain antiinterference ability in the starting stage.

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张铁,洪景东,刘晓刚.基于弹性摩擦模型的机器人免力矩传感器拖动示教方法[J].农业机械学报,2019,50(1):412-420.

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  • 收稿日期:2018-07-24
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  • 在线发布日期: 2019-01-10
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