運用致動器量測之振動台運動分析與關鍵參數識別方法－以MAST為例

Kinematics and Identification Study Applied to the Shaking Table by Using the Actuator Measurement: Take MAST for example

10.6849/SE.202209_37(3).0005

賴晉達(Chin-Ta Lai)；葉士瑋(Shih-Wei Yeh)；翁樸文(Pu-Wen Weng)；蕭輔沛(Fu-Pei Hsiao)；黃百誼(Bai-Yi Huang)

振動台 ； 史都華平台 ； 致動器位移轉換 ； 力量座標轉換 ； 參數識別 ； shaking table ； Stewart platform ； actuator kinematics ； force transformation ； parametric identification

結構工程

37卷3期（2022 / 09 / 01）

81 - 104

繁體中文

為了解或驗證結構物之耐震性能，將待測物安裝於振動台檯面進行動態測試，為最直接且廣為採納之研究方法。配置於國震中心臺南實驗室之關鍵零組件測試系統（Multi-Axial Seismic Test System，簡稱MAST）係以油壓驅動之六軸向振動台。該系統配置為史都華平台（Stewart platform）式，僅採用6支致動器即可實現六自由度運動，可降低建置成本以及系統冗餘度。本文將簡介MAST系統，而後推導MAST系統致動器伸長量與檯面位移之轉換關係，以及致動器出力與等值檯面作用力之轉換關係。為能有效模擬MAST系統之動態行為，以便進行實驗規劃，本文亦將提出MAST系統等效質量及等效摩擦力與阻尼力之識別方法。由實驗數據識別之等效質量顯示，其與MAST原始設計之理論質量結果相當接近，表示本文提出之等效質量識別方法之可靠性。此外，相關研究通常以庫倫摩擦模型或Bouc-Wen模型描述摩擦力，本文採用Bouc-Wen模型描述元件相互位移產生之摩擦力，因該模型於速度轉折處為連續且可微分，更易於應用於數值分析與模擬；後經迴歸分析獲取關鍵參數，發現數值模擬結果與MAST系統量測之實驗數據相近，顯示利用Bouc-Wen模型模擬MAST系統內摩擦力之可行性。綜上所述，此研究將有助於了解振動台系統動態特性及探討相關識別技術，並能提供關鍵參數於後續進行數值分析以及後續與結構試體互制之動態模擬之研究。

A shaking table test is one of the experimental methods widely adopted to inspect the seismic performance of structures. A multi-axial seismic test system (MAST) equipped in Tainan Laboratory, National Center for Research on Earthquake Engineering (NCREE) is a hydraulic powered six-degree-of-freedom shaking table, which consists of a rigid mass and six actuators. The placement of the actuators follows the design of the Stewart platform. Hence the MAST system can achieve 6-DOF dynamic motion with the least amount of actuators; in other words, reducing the cost and the redundancy of the system. This article introduces the MAST system in the very first paragraph. Then the kinematics study based on the geometric relation between the actuators and the rigid platen will apply to the forward and inverse conversion of the actuator displacement/force and the platen 6-DOF displacement/force. In addition, this study proposed system identification methods to evaluate the equivalent mass and the equivalent damping and friction force of the MAST system, which are critical characteristic parameters for simulating the system's dynamic responses. As a result, the identified equivalent mass approximates the design value, which shows the high fidelity of the proposed system identification method. Moreover, a Bouc-Wen model, which is wildly adopted on describing the friction force and numerical-friendly, is validated in this study. The parameters for Bouc-Wen model are obtained through the regression analysis by utilizing the experimental data. While the simulated results based on the Bouc-Wen model are consistent with the experimental data, it can be concluded that the equivalent mass and damping force of the MAST system or similar systems can be quickly evaluated through the proposed identification methods in this study. With the help of the proposed method, it's possible to simulate the table motion of the MAST system or similar shaking table system, and then conduct further study, such as dynamic interaction between the system and the specimens.

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