STUDY ON OPTIMAL PATH AND OPERATING TIME FOR DRIVING A MANIPULATOR WITH SAVING ENERGY

火电厂排放的CO_2气体使地球环境升温，节约机械手的能耗对改善地球环境具有重要意义。因此，本计画主要研究一垂直关节式机械臂在PTP运动中，以最小化耗散能量的最佳路径与作业时间。粗略地估计出一条全局最优路径，使得较重的环节向引力方向加速，向反引力方向减速。该路径被用作迭代法求解非线性两点边值问题的起始函数。仿真结果表明，当操作时间选择为最优时，所提出的最优路径与传统路径相比，能耗可降低1/14 ~ 1/30.为了实现仿真结果，对双电机直接驱动的双连杆机械手进行了改进，使第一、第二连杆可实现360 °以上的旋转，并对连杆的惯性、库仑摩擦力等参数进行了辨识。通过数字信号处理器的仿真得到了机械手的最优速度函数，并验证了实验结果的正确性。在伺服驱动器的输入端测量耗散能量。测量的能量比模拟结果的能量稍大。由三相逆变器实现的伺服驱动器的转换损耗导致了微小的差异。

It is important to save the dissipated energy even of manipulators for improving the environment of the earth which is warmed up by CO_2 gas emitted from thermal power plants. Hence, this project is studied about an optimal path and operating time which minimize the dissipated energy in PTP motions of a vertically articulated manipulators. A globally optimal path is roughly estimated so that the heavier link is accelerated toward gravitational direction and decelerated toward anti-gravitation. This proposed path is used as a starting function of the iteration method solving a non-linear two-point boundary-value problem. The simulation results show that a proposed optimal path can reduce the dissipated energy to 1/14〜1/30 compared with conventional path when the operating time is selected so as to be optimal.In order to implement the simulation results, two-link manipulator driven by two direct drive motors is improved so that the first and second links can be rotated over 360 degree, and the parameters such as inertias and Coulomb friction forces of the links are identified. When the manipulator are commanded to be optimal velocity function obtained by the simulations via a digital signal processor, the path from the experimental result are verified without error. The dissipated energy is measured at input of servo-driver. The measured energy is a little larger than the energy of the simulation result. A little difference is due to the conversion loss of the servo-driver implemented by three-phase inverter.