遠端操作系統之網路延遲訊號估測與影像輔助機制設計

Abstract

本論文建構了利用網路攝影機監控的遠端循軌操作系統，發展網路系統控制架構與操作輔助機制，成功降低網路延遲對於系統響應與人為操作造成的循軌誤差，並有效地降低任務完成時間。 網路延遲對系統響應造成的影響可分為兩部分：底層網路系統控制響應與造成上層操作時之困難。針對底層系統響應之改善，模型預測控制器(model predictive controller, MPC)能及時地計算出最符合預期響應之控制訊號，且比一般控制器更能克服複雜且不定因素對系統造成的影響；而通訊擾動估測器(communication disturbance observer, CDOB)不需要延遲時間模型，將網路延遲視為擾動量進行估測後做為回授補償值，本論文並且提出一CDOB改善架構，消除在取樣頻率不足時發生之穩態誤差，最後利用權重分配因子將CDOB與MPC估測之整合迴授訊號最佳化，實驗證明在平均450 ms之延遲時間下能夠大幅降低響應震盪幅度84.5%與縮短收斂時間87.6%。 最後，針對網路延遲效應降低系統上層操作透明度進而造成循軌誤差，設計操作輔助機制，改善操作困難。首先，利用不同工作空間座標下之相對位置命令映射，降低循軌誤差並縮短完成時間縮短。但由於在影像定位誤差時需另有校正機制，所以考慮人因與網路延遲效應，提出操作點預測輔助機制，克服影像定位對輔助機制之影響，並在需要進行微調時切換至perfect delay compensation (PDC)控制架構，經實驗結果證明可有效降低循軌誤差並縮短完成時間。

This thesis develops a control scheme composed by a model predictive controller (MPC), a communication disturbance observer (CDOB), and a feedback weighting mechanism in order to overcome the inevitable delay time in an Internet-based teleoperation system. The CDOB mainly compensates for the time-delay effect by treating it as a disturbance without the knowledge of the delay-time model. Moreover, this thesis proposes an improved scheme of CDOB in order to eliminate the steady-state error existed in a networked control system without a sufficient sampling rate. Meanwhile, the MPC adopted in this thesis predicts the best control signal in order to optimize the system performance. Generally, the time-delay effect usually decreases the transparency of the network controlled system and three assist strategies are presented in this thesis as: (1) virtual operation point, (2) prediction operation point, and (3) fine adjustment switching mechanism. Contouring motion experiments on a 2-DOF virtual manipulator validates the proposed assist mechanism.