引用本文: 杜玉红, 刘栋财, 董广宇. 基于广义坐标形式动力学的6-RUS并联机器人零力控制[J]. 机器人, 2023, 45(3): 333-344.
DU Yuhong, LIU Dongcai, DONG Guangyu. Free-Force Control of 6-RUS Parallel Robot Based on Dynamics of Generalized Coordinate Form[J]. ROBOT, 2023, 45(3): 333-344.
 Citation: DU Yuhong, LIU Dongcai, DONG Guangyu. Free-Force Control of 6-RUS Parallel Robot Based on Dynamics of Generalized Coordinate Form[J]. ROBOT, 2023, 45(3): 333-344.

## Free-Force Control of 6-RUS Parallel Robot Based on Dynamics of Generalized Coordinate Form

• 摘要: 针对6-RUS并联机器人的拖动示教零力控制问题, 提出基于广义坐标形式动力学模型的解决方法。首先, 引入动态摩擦模型, 建立广义坐标形式的动力学模型; 利用全局区域法获取电机在工作空间某位置的实际输出转矩, 并采用Savitzky-Golay(SG)算法平滑噪声, 分析机构自身噪声对转矩数据的影响。然后, 结合6-RUS并联机器人动力学方程构建电机的期望输出转矩, 补偿电机的期望转矩与实际转矩之间的误差, 实时跟踪电机转矩实现零力控制。最后, 在6-RUS并联机器人平台上进行实验。结果表明, 在不同负载情况下, 电机的预测与实际输出转矩之间误差均在8.25% 以下; 在完成相同示教过程中, 本文方法所需的末端力矩仅为2.2 N·m, 而基于重力矩与摩擦力矩补偿的零力控制方法为3.4 N·m, 验证了本文零力控制法的有效性。与传统零力控制方法相比, 该方法简化了动力学建模步骤, 提高了构建期望电机转矩的效率, 解决了机器人静止、启动、运动反向阶段期望电机转矩预测不精确的问题, 同时实时补偿了转矩误差, 使得机器人获得更好的拖动效果。

Abstract: A dynamic model based on generalized coordinates is proposed to solve the free-force control problem in drag teaching of 6-RUS parallel robot. Firstly, the dynamic friction model is introduced, and a dynamic model is established in the form of generalized coordinates; the actual output torque of the motor in a workspace position is obtained by the global area method, and the Savitzky-Golay (SG) algorithm is used to smooth the noise and analyze the influence of the mechanism's own noise on the torque data. Then, the expected output torque of the motor is constructed based on the dynamic equation of 6-RUS parallel robot, the error between the expected motor torque and the actual torque is compensated, and the motor torque is tracked in real time to achieve free-force control. Finally, experiments are carried out on the 6-RUS parallel robot platform. The results show that the errors between the predicted and actual output torques of the motor are less than 8.25% in different load conditions. In the same teaching process, the end torque required by the proposed method is only 2.2 N·m, and 3.4 N·m is required by the free-force control method based on the compensation of gravity and friction torques, which verifies the effectiveness of the proposed free-force control method. Comparing with the traditional free-force control method, the proposed method simplifies the dynamic modeling steps, improves the efficiency of constructing the expected motor torque, and solves the problem of inaccurate prediction of the expected motor torque in the stationary, starting, and reverse motion phases of the robot. The torque error is compensated in real time, so that a better drag effect can be obtained.

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