影像伺服動態追蹤控制應用於三軸氣壓並聯式平行機械臂之研究

Abstract

本文旨在以單一不含深度資訊之網路攝影機，加入影像演算法應用於三軸氣壓並聯式機構機械臂，進行三維度之物件追蹤控制。影像運算單元可由影像辨識得到物件面積大小、位置，完成三維方向誤差的即時計算，資料以無線網路傳送至機械手臂端之控制器，以執行動態物體之追蹤控制。 本研究發展以顏色辨識操控機械臂的方法，並使用色彩轉換消除空間中光線及陰影的干擾。網路攝影機取得影像後經過多個處理程序，最終得到座標資料，回傳機械臂端點下一瞬間之即時座標。其中的影像處理單元計算色彩轉換、雜訊消除和形態學，以計算目標物大小及位置。 機械臂控制器設計方面，為了提高控制精準度，使用以傅立葉函數近似法為基底之適應性滑動模式控制器結合 追蹤補償之控制器，對三軸無桿氣壓缸進行即時位置及軌跡控制，並利用推導出之正向運動學模型算出當前手臂端點卡氏座標，再與目標距離誤差座標相加，獲得下一取樣時間機械臂之絕對位置。 最後，經過實驗驗證本文提出之方法的可行性，證實此系統可成功導引三軸式機械臂之端點順利地即時追蹤動態目標。

The objective of this study is to develop a 3-dimensional object tracking with a single RGB camera on the three-axial pneumatic parallel manipulator. The image processing unit calculates the area of target and position of the centroid, therefore, to retrieve the three-dimensional errors in real-time. Simultaneously, the errors are being transmitted to the control unit through wireless internet. In this study, a robust color recognition method is utilized to control the manipulator. Images are transformed into YCbCr model first in order to reduce the noise of light. Once the three-dimensional errors are retrieved, the information is transmitted to the manipulator controller to determine the end-point position of the next sampling time. Thus, the end-effector of the manipulator can move to track the dynamic position of the object. The image processing unit achieves the color transformation, noise elimination, morphology of structure and target position determination. In order to control the three-axial pneumatic parallel manipulator and improve the tracking accuracy, a Fourier series-based adaptive sliding mode controller with H-infinity tracking performance (FSB-ASMC+ controller) is proposed. The x-y-z errors are added to the current end-point position, which is calculated according to the forward kinematics, for the next moment movement. Finally, the experiments of the three-axial pneumatic manipulator end-effector integrated with the color recognition algorithm demonstrate that the proposed methods can achieve the dynamic object tracking successfully.