Abstract This paper proposed a design method of trajectories for detecting the excessive clearances of passive joints in a DELTA robot on the basis of the phenomenon that the actuation torque waveform fluctuates due to the collision between joint elements. We introduced “Joint Impact Index,” as an index to evaluate the magnitude of actuation torque fluctuation due to the collision at the passive joints with clearances. In order to simplify the problem of the clearance detection, this paper proposed to use a trajectory specially designed for the detection of each joint’s clearance, called “target trajectory”. For the design of the target trajectory, objective functions were defined based on the Joint Impact Index. Target trajectories obtained by solving the multi-objective optimization problem were applied to an industrial robot, and experiments were conducted. The relation between the detection performance in the experiments and the distribution of Joint Impact Index for the designed target trajectories was investigated and the effectiveness of the proposed method was discussed.

中文翻译：

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基于驱动力矩测量的并联机器人关节间隙检测目标轨迹设计

摘要 针对DELTA机器人被动关节间隙过大检测轨迹设计方法，基于关节元件碰撞引起的致动力矩波形波动现象。我们引入了“关节冲击指数”作为评估因间隙被动关节碰撞引起的致动扭矩波动幅度的指标。为了简化间隙检测问题，本文提出使用专门为检测每个关节间隙而设计的轨迹，称为“目标轨迹”。对于目标轨迹的设计，基于联合影响指数定义了目标函数。通过求解多目标优化问题获得的目标轨迹应用于工业机器人，并进行了实验。研究了实验中的检测性能与设计目标轨迹的联合冲击指数分布之间的关系，并讨论了所提出方法的有效性。