Dynamics and Control of Nano-Motion Mechanisms

本研究的目标是实现既具有纳米级定位分辨率又具有毫米级定位范围的运动机构。本课题包括三个研究方向：(1)纳米运动机构动力学；(2)冗余机构控制；(3)精密非接触磁致动器。在亚微米到毫米量级的运动范围内，对精密机器人谐波减速器和空气轴承丝杠步进机构的动态特性进行了实验研究。这两种机制都表现出随运动范围不同的宏观动力学和微观动力学。(2)冗余机构的控制通过理论和实验验证了最适合冗余两级定位系统的控制器。两级定位系统包括作为粗运动机构的滚珠丝杠和直流电机，以及作为细运动机构的PZT致动器和弹性铰链机构。系统采用PID、最优状态反馈、H_<inf>、滑模、模糊和神经控制器。分析了台阶高度、工作台质量和恒载荷变化对定位性能的影响。其中，模糊控制器和神经控制器的鲁棒性最好。(3)高精度和非接触式磁致动器对采用电磁致动器的无传感器控制系统的定位精度进行了检验。采用观测器和磁通传感器对两种类型的位移估计器进行了测试。估计器的位移分辨率为0.1 ~ 0.15 μm。

The aim of this research is to realize motion mechanisms with not only nanometer positioning resolution but also millimeter positioning range. This research project consists of three subjects : (1) Dynamics of Nano-motion Mechanisms, (2) Control of Redundant Mechanism, and (3) Precision and Non-contact Magnetic Actuators.(1) Dynamics of Nano-motion Mechanisms Dynamic characteristics of a harmonic speed reducer for precision robots and an air bearing lead screw mechanism for steppers are experimentally examined within several moving ranges from sub-micrometer to millimeter orders. Both the mechanisms show macro-dynamics and microdynamics depending on the moving ranges.(2) Control of Redundant Mechanism The most suitable controller for redundant two-stage positioning system is theoretically and experimentally examined. The two-stage positioning system includes a ball lead screw and a DC motor as a coarse motion mechanism, and a PZT actuator and an elastic hinge mechanism as a fine motion mechanism. PID, optimal state feed back, H_<inf>, sliding mode, fuzzy and neural controller are applied to the system. Effect of step height, the table mass and constant load changes on the positioning performances are evaluated. The fuzzy and neural controllers show the best robustness in the seven controllers.(3) Precision and Non-contact Magnetic Actuators Positioning accuracies of sensorless control system using electromagnetic actuators are examined. Two types of displacement estimators using an observer or a magnetic flux sensor are tested. The displacement resolutions of the estimators are 0.1 - 0.15 μm.