應用霍爾感測器與磁性環實現二維壓電致動器旋轉馬達之 主動角度控制

Abstract

本研究目的為二維旋轉壓電馬達之主動角度控制，與本實驗室團隊在之前開發出的二維旋轉壓電馬達進行系統整合，達到可精準控制轉盤轉子角度的研究目標。在此控制系統配置中，本研究在轉盤轉子外圍設計一個可使用逕向充磁N35強力磁鐵環以及2個霍爾感測器即可讀取出轉動角度的感測技術，並將此做為控制系統的回授訊號，輸入至NI myRIO-1900 進行PID角度控制。本研究以本實驗室團隊所開發之自走式二維壓電平板致動器做為控制對象，首先利用希爾伯特轉換分析方法，定義一成本函數，並藉由此設計出最佳驅動訊號給予至不同壓電片組合，疊加出效率最佳之順時針和逆時針方向之旋轉行進波。同時透過數值模擬進行分析，以及利用有限元素模擬驗證此尋找最佳驅動訊號方法的可行性，最後實際操作雷射測振儀觀察二維旋轉壓電致動器表面波形驗證最佳驅動訊號方法，並比較使用本研究所開發之角度回授控制技術研究可操控的角度及精度。經由實驗驗證，此系統在順時針方向具有著8.13V的線性區，而在逆時針方向，具有著7.69 V的線性區，在透過閉迴路系統辨識建立出二維旋轉壓電致動器轉移函數模型，並透過根軌跡圖設計出符合臨界阻尼系統之PID參數，在移動1度時，順時針精度可以達到0.0087度，逆時針精度可以達到0.0076度，達到研究目標。最後以不同角度步階實驗以角度往復實驗來測試系統性能。

The aim of this study is to design an active angle control system for a rotating piezoelectric motor to achieve the goal of angular precision control. This active angle control system integrates a rotating piezoelectric motor that was previously developed by our team. The angular sensing method is constructed by a radially magnetized N35 magnet ring and two Hall sensors, and the measured angle is used as the feedback signal using a NI myRIO-1900 for PID angular control. To optimize this rotational piezoelectric motor, we first define a cost function using the Hilbert transform to identify the optimal drive parameters. Clockwise and counterclockwise rotating waves can be effectively activated by superimpose bending vibrations induced by different combinations of piezoelectric actuators. Numerical simulation and finite element method are also used to verify the feasibility of this. Finally, we conduct experimental studies and verify it with a laser vibrometer. The capability to control rotational angle and accuracy of the angle feedback control method also are verified. The experimental results demonstrated that the system has a linear region of 8.13 V in the clockwise direction and a linear region of 7.69 V in the counterclockwise direction. A system identification process is used to design the closed-loop system, and the root locus diagram is used to optimize the PID control parameters for designing a critical damping feedback system. Applying this system, the clockwise accuracy can reach 0.0087 degrees, and the counterclockwise accuracy can reach 0.0076 degrees at 1-degree movement. Finally, the system performance is tested with experiments involving incremental steps at different angles and reciprocating motion at varying angles.