面向六关节机器人的位置域控制

Position domain control technology for six-joint robots

  • 摘要: 多轴联动下的串联多关节工业机器人在空间轨迹运动时,在时间上保证各关节轴单独具有良好的跟踪性能,而由于机械电气的迟滞效应,并不能完全保证理想的轮廓轨迹,这说明各个伺服轴的运动在几何空间中的同步非常重要。针对运动指令与实际位置之间的迟滞所带来的机器人末端轮廓精度不高的问题,本文结合工业机器人现有的运动学和动力学以及传统的PID控制理论,研究了六关节机器人位置域控制算法。将机器人空间轮廓轨迹的控制,通过采用主−从运动关系实时建立的方法,将时域中的各个伺服关节的同步控制方法,变换到位置域的各个伺服关节的主−从跟随的控制方法,在实现位置域的同步控制的同时,引入基于位置域的PD控制,减少了主−从跟随控制的跟随误差,从而整体提高机器人末端的轮廓运动精度。该方法在Linux CNC(Computerized Numerical Control)数控系统上,以某公司HSR-JR605机器人为对象进行了实验,证明采用位置域控制方法对六关节机器人空间运动轨迹精度的提高有积极作用。

     

    Abstract: In the context of the rapid development of intelligent manufacturing, high-precision motion control of industrial robots has attracted increasing research attention. High-speed and high-precision motion control is a development trend associated with the current industrial robots. Industrial transformation and upgradation can be accelerated only via the independent research and development of robot core technologies, including robot high-precision control systems, ensuring the transition of the manufacturing industry in China toward intelligent and digital development. Currently, the contour tracking error associated with majority of the multiaxes CNC machine tools and multijoint industrial robots is a common problem. A good tracking performance can be achieved in time with respect to each joint axis when the space trajectory of the serial multijoint industrial robot changes under multiaxes linkage. The ideal contour trajectory cannot be fully ensured because of the mechanical and electrical hysteresis effects. Therefore, the synchronization of the motion of each servo axis in the geometric space is very important. In this paper, the existing kinematics and dynamics of industrial robots were combined with the traditional PID control theory for studying position domain control algorithm of the six-joint robot to resolve the problem of low accuracy associated with the robot end profile, which can be attributed to the lag between the motion instruction and the actual position. The algorithm uses the method of real-time establishment of the master–slave motion relation for controlling the spatial contour trajectory of the robot. It further transforms the synchronization control method of each servo joint in the time domain into the master–slave follow control method of each servo joint in the position domain. While realizing synchronization control in the position domain, PD control based on position domain was introduced to reduce the following error of the master–slave following control, improving the overall accuracy of the contour motion of the robot end. The method proposed in this paper has been tested on the Linux CNC numerical control system with a company’s HSR-JR605 robot, indicating that the position of the domain control method employed positively affects the accuracy of six articulated robot space trajectory.

     

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