Finite Element Based Input Shaping Design for Suppressing Motion-Induced Vibrations

有限元素分析於撓性長距離移動系統之輸入修正設計與應用

陳韋如(Weiju Chen) ； 陳國聲(Kuo-Shen Chen)

《中國機械工程學刊》 42卷1期 (2021/02) Pp. 1-10

摘要

Input shaping is an effective method for suppressing motion-induced vibration to enhance the motion performance in point-to-point maneuverers. However, the success of shaper design depends on the accuracy of system dynamics but such an approach could not yield effective dynamic models with sufficient accuracy for systems with complex boundary conditions, motion constraints, and structural behaviors. In this work, it is proposed to hire finite element dynamic simulation directly in both trajectory planning and input shaping design. Two flexible motion systems are designed for serving as the test beds to ensure multiple mode excitations during transportation for evaluating the effectiveness in finite element simulation. The results confirm the effectiveness of using input shaping in vibration suppression and both the experimental and the simulation results agree to each other very well. Several case studies using finite element simulation are then followed for elucidating the possible future applications of the proposed approach in real engineering designs. It is believed that the proposed shaper design approach by hiring finite element simulation can handle many ad hoc issues such as nonholonomic constraints, time-varying and nonlinear structural dynamics, and possible power and bandwidth limitation in actuators.

關鍵字

Vibration suppression ； Input shaping ； Finite element simulation ； Dynamics

並列摘要

長距離移動系統運作過程常因致動器加減速造成晃動量，並於完成作動後殘餘殘留振動量，降低系統工作精度與效率，並增加工作時間，甚至造成工安威脅。常見的振動抑制策略以回授控制的方式對系統進行振動抑制，此方法雖提供了系統對抗外界干擾的能力，具有良好的強健性，但須加裝額外的感測器與回授控制之致動器，大幅增加系統成本與複雜度。而輸入修正法提供了一個經濟且簡便的減振方式，然而傳統上輸入修正法主要依靠解析動力模型，但對結構與邊界條件複雜且具耦合之系統，解析解之獲得具有相當的挑戰性，且其形式也可能過分複雜，失去解析解簡潔的本意。本文在此提出以有限元素動力分析模擬撓性長距離移動架構，並在動態模型中設計輸入修正法對系統進行振動抑制，相較於解析解可更詳細描述系統之運動行為，且在多自由度系統的模擬上具有更佳的便利性。接著設計長距離移動系統中常見的天車系統與機械手臂系統之等效實驗模型，比較實驗與有限元素動態分析結果以驗證力學分析準確性以及所提想法之可行性。最後我們將有限元素法的應用延伸至實際尺寸之長距離移動系統，討論各種輸入修正方法於系統之振動抑制情況。本研究將有助於長距離移動系統振動抑制之相關應用。