結合力量微分感測器與擴增型觀測器之力量估測研究

Abstract

力量訊號可透過感測器或使用數學模型的觀測器獲得。在感測器方面，應變規 (strain gauge) 及壓電式 (piezoelectric, Piezo.) 力量感測器是最常用的力量感測器；相較於應變規，壓電感測器的剛性高、量測頻寬大、體積小且耐用，但有飄移問題，無法量測靜態力量訊號。為解決低頻靜態量測的問題，許多方法已被提出，然而每個不同解決方法皆衍伸出不同缺點。另一方面，使用數學模型的擴增型狀態觀測器 (extended state observer, ESO) 礙於有限的位置感測解析度，使其無法有效地觀測高頻力量訊號。為了獲得良好的力量訊號，本文使用商用的壓電式傳感器本體，設計力量微分 (yank) 感測器，然後使用一個估測器，其擷取ESO輸出的低頻部分，並結合yank訊號積分後的高頻部分。如此，可獲得比ESO更高動態的力量訊號，且可量測靜態力量訊號，不會有壓電感測器的飄移問題。除了獲得良好的力量訊號，yank訊號可用於增加力量回授系統阻尼，提高控制系統頻寬。本文使用之實驗環境為實驗室成員共同研發設計、組裝之一維線性馬達實驗平台，控制核心使用美國德州儀器公司 (Texas Instruments, TI) 生產之TMS320C6713 DSK開發版，結合Xilinx公司的XCV-50PQ204-6C晶片為主之現場可程式化邏輯閘陣列 (Field Programmable Gate Array, FPGA)，搭配硬體描述語言 (VHSIC hardware description language, VHDL) 撰寫數位邏輯電路，再透過TI的編輯軟體Code Composer Studio (CCS) 編譯C語言之控制程式。由實驗結果可知，本文所設計之力量微分感測器能夠準確的量測到力量微分訊號，搭配ESO能準確的觀測到系統的位置、速度與力量訊號，此外，做力量控制回授結果較應變規頻寬較寬、響應快，進一步提升系統性能。The signal of force can be obtained through sensors or observers using mathematical models. In terms of sensors, strain gauge-based and piezoelectric force sensor are the most commonly used force sensors. Compared with strain gauge-based sensor, the piezoelectric force sensor has higher rigidity, larger dynamic range, smaller size and durability, but it has drift problems and cannot measure static force signals. To solve the problem of static force, many methods have been proposed, but each of the different solutions has different drawbacks. On the other hand, extended state observer (ESO) using mathematical models cannot effectively observe high-frequency force signals due to the limited position sensing resolution.In order to obtain a good force signal, a commercially available piezoelectric transducer is used to design a yank sensor, and then use an estimator that captures the low frequency part of the ESO output and combines the high frequency part of the integrated yank signal. In this way, a higher dynamic force signal than ESO can be obtained, and a static force signal can be measured without the drift problem of the piezoelectric force sensor. In addition to obtaining a good force signal, the yank signal can be used to increase the damping of the force feedback system and increase the bandwidth of the control system.The experimental environment in this research is a one-dimensional linear platform designed and assembled by lab members. The control core uses the TMS320C6713 DSK from Texas Instruments (TI), and is matched with an field-programmable gate array (FPGA), XCV-50PQ204-6C chip from Xilinx, Inc. A digital logic circuit is designed using the VHSIC hardware description language (VHDL), and a control program in C language is developed using TI’s editing software Code Composer Studio (CCS). It can be seen from the experimental results that the yank sensor designed in this thesis can accurately measure the force derivative signal, and the ESO can accurately observe the position, speed and force signal of the system. In addition, the bandwidth and response of force control feedback results are better than those using the strain gauge-based sensor, further improving system performance.