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研究生: 林庭琮
Lin, Ting-Tsung
論文名稱: 應用 LSTM 模型於機器人控制系統之轉移函數及控制訊號估測:以數位孿生為基礎
Application of LSTM Models for Transfer Function and Control Signal Estimation in Robotic Control Systems: A Digital Twin-Based Approach
指導教授: 蘇文鈺
Su, Wen-Yu
學位類別: 碩士
Master
系所名稱: 電機資訊學院 - 資訊工程學系
Department of Computer Science and Information Engineering
論文出版年: 2025
畢業學年度: 113
語文別: 英文
論文頁數: 97
中文關鍵詞: 控制系統系統轉移函數機器學習數位孿生ROS2Unity
外文關鍵詞: control system, system transfer function, machine learning, digital twin, ROS2, Unity
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  • 本論文使用資料驅動的方式搭配上 LSTM 模型,求得近似的控制系統轉移函數,並對模型進行修正、行為分析與極點零點之比對。
    為了驗證此方法的可靠性,我們先於虛擬的系統進行實驗,再將此論文的方法套用在實體馬達系統上,虛擬控制系統的驗證方式如下:首先建立數個階數不同的受控體 (Plant) 與對應之 PID 控制器兩個元件的簡單負回授系統,以多種不同的輸入訊號作為測試,並收集巨量的測試資料,以之完成 LSTM 模型訓練後進行此模型的系統頻率響應之轉換,並經過正規化後與上述系統的轉移函數進行極點與零點的比較,證明此一方法的可行性後,隨後在使用伺服馬達之實體動態系統中同樣以透過資料驅動的方式求得系統轉移函數,以利後續控制器的調整以及控制訊號的設計。
    本論文另涵蓋使用 ROS2 環境之數位孿生平台,測試並模擬移位機器人及人體機器人模型在 Unity 物理引擎驅動下的移動情形並進行受力分析,作為安全性評估的依據,未來將整合此學習模式於 Unity 中移位機器人的馬達控制,以達到完整模擬實體場域中的移位機器人之控制情形。

    This work employs a data-driven approach combined with an LSTM model to approximate the transfer function of a control system. The model is then refined, analyzed in terms of system behavior, and compared based on its poles and zeros.
    To verify the reliability of this method, experiments are first conducted in a virtual environment before applying the approach to a physical motor system. The validation process in the virtual control system is as follows: several simple negative feedback systems are constructed, each consisting of a plant with different system orders and a corresponding PID controller. Various input signals are used for testing, and a large amount of data is collected. After training the LSTM model with this dataset, the system’s frequency response is obtained and normalized. The resulting transfer function is then compared with that of the original system by analyzing poles and zeros to demonstrate the feasibility of the proposed method. Once validated, the same data-driven approach is applied to a physical dynamic system using a servo motor to estimate its transfer function, facilitating subsequent controller tuning and control signal design.
    Additionally, this work includes the development of a digital twin platform using the ROS2 environment to test and simulate the movement of a transfer-assist robot and a human-like robot model under Unity’s physics engine. A force analysis is conducted as the basis for safety evaluation. In the future, this learning-based approach will be integrated into the motor control of the transfer robot in Unity, enabling full simulation of its behavior as it would occur in a real-world environment.

    中文摘要 i Abstract ii Contents iv List of Tables vii List of Figures viii 1 Introduction 1 1.1 Motivation 1 1.2 Literature Review 2 1.3 Proposed Methodology 3 2 Related works 6 2.1 Dynamic System Analysis 7 2.1.1 Basic Control Elements and Block Diagram of Control Systems 8 2.1.2 System Identification 10 2.1.3 Bilinear Transform 11 2.2 Long Short-Term Memory Networks (LSTM) 12 2.3 ROS 16 2.3.1 ROS 2 Development Tools and Module Support 19 2.3.2 ROS 2 Communication Architecture and Data Exchange Mech-anism 19 2.4 Digital Twin 21 2.4.1 Unity as a Digital Twin Simulation Platform 23 2.5 CAN (Controller Area Network) 25 2.5.1 Physical Architecture and Wiring Topology of CAN Bus 27 2.5.2 CAN Data Frame Format Description 27 3 This work 29 3.1 Dynamic Motor System Modeling Using LSTM 30 3.1.1 Virtual Dynamic System 30 3.1.2 Physical Environment Data Measurement 34 3.1.3 LSTM Training Dataset Preprocessing and Model Construction 36 3.1.4 System Analysis of the LSTM Model 37 3.2 ROS2 Integration 38 3.3 Unity Simulation Environment Setup 39 3.3.1 Robot Model Creation 39 3.3.2 Control Script Design 40 3.3.3 Articulation Body Parameter Configuration 40 3.3.4 Data Collection and Storage 41 3.4 Motion Capture and Human Model Simulation 42 4 Results 44 4.1 Dynamic Motor System Analysis 44 4.1.1 Analysis of the Virtual Motor System 45 4.1.2 LSTM Model Training 50 4.1.3 Analysis of Differences Between Model Frequency Response and Bode Plot 59 4.2 Analysis of the Physical Motor System 61 4.2.1 CAN Protocol Specification 61 4.2.2 Motor Characteristics 63 4.2.3 LSTM Model Training 64 4.3 Unity Object Setup and Testing 73 4.3.1 Joint Physical Parameter Configuration 74 4.3.2 Arm Motor Testing 75 4.3.3 Mocap Motion Simulation Test 79 5 Future works 83 References 84

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