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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/30679

Title: 承受移動動態負載之精密機械的動態分析與振動控制
Dynamic Analysis and VI Bration Control of a Precision Machine Subjected to Moving Dynamic Loads
Authors: 林益煌
Contributors: NTOU:Department of Mechanical and Mechatronic Engineering
Keywords: moving dynamic loads;precision positioning;dynamic analysis
Date: 2011
Issue Date: 2012-04-13T01:18:33Z
Publisher: 行政院國家科學委員會
Abstract: 本計畫探索承受移動動態負載之精密機械的動態特性與振動控制。不同於傳統考慮移動負載問題的土木構造,例如橋梁或鐵道,本計畫係就精密機械,例如高速精密鑽床或精密定位平臺,進行設計與分析。因此需特别留意移動動態系统之動態行為。本計畫考慮於彈性支撐結構上之具二個自由度的移動動態系统,首先將建立整體系统之有限元素模型以利複雜邊界條件之處理。不同於考慮恆定的移動速度或加速度的傳統移動負載分析,本計畫考慮之移動動態系统係以一般化之運動形式行走,自靜止狀態迅速移至下個工作位置而仍保持靜止,通常係基於最小旅行時間策略以獲得最大之生產效率。運動形式具有三個階段,即迅速加速、迅速減速、和便利後續操作之安定期。要提供這樣運動形式,移動動態系统需承受瞬間施加之外力以加速及減速,很容易導致嚴重振動,而降低生產效率和產品品質。我們將檢驗整體系統之動態特性以精確找出關鍵參數,例如移動動態系统之支撐狀態、外力特徵、和彈性支撐結構特徵等對精密機械性能表現的影響。接著探討改變敏感參數之結構修正和被動式振動控制以改善系统性能。本策略不用可觀費用而使系統性能得以改善。不需額外的外在能量,且系统維護簡易。最後,為進一步提高精密機械之性能,將探討主動振動控制策略,藉由閉迴路回饋控制器的統合調節,以外在激振機構提供可觀之振動控制能力。在今日超精密高速機械之精確性與效率的嚴格要求下,主動振動制抑策略的應用將扮演關鍵之角色。
This project aims to explore dynamic characteristics and vibration control of a precision machine subjected to moving dynamic loads. Opposed to the traditional consideration of moving load problems for civil structures, such as bridges or railroads, the subject matter studied in this work is related to the design and analysis of precision machines, such as high speed precision drilling machines or precision positioning platforms. Consequently, special attention must be paid on the dynamic behavior of the moving dynamic system. In this project, a moving dynamic system with two degrees of freedom traveling on a flexible support structure will be considered. The finite element model of the integrated system will first be formulated to facilitate the treatment of a system with complex boundary conditions. Unlike the traditional moving load analysis considering a constant moving speed or acceleration, the moving dynamic system considered in this work travels with a general movement profile. From a stationary condition, it rapidly moves to the next operation position while still remaining stationary. The operation usually incorporates a minimal traveling time strategy for maximal production efficiency. The movement profile involves three motion stages, i.e. rapid acceleration, rapid deceleration, and settling for subsequent operation. To provide such a movement profile, the moving dynamic system is subjected to sudden applications of external excitation to accelerate and to decelerate, which can easily result in severe vibration and may reduce the production efficiency and the product quality. We shall examine the dynamic characteristics of the entire system to pinpoint the crucial parameters, such as support conditions of the moving dynamic system, forcing function characteristics, and flexible base support characteristics, on the performance of the precision machine. Structural modification by changing the sensitive parameters and passive vibration control will be studied subsequently for improvement of system performance. This strategy provides quality enhancement without considerable cost. No additional external energy is required and little effort is needed for system maintenance. Finally, to further enhance the performance of the precision machine, active vibration control strategy will be examined, which provides appreciable vibration control capability by external excitation mechanisms orchestrated by a closed loop feedback controller. The application of the active vibration suppression strategy can be crucial if strict requirements on accuracy and efficiency are imposed for today’s ultra precision high speed machines.
Relation: NSC100-2221-E019-007
URI: http://ntour.ntou.edu.tw/handle/987654321/30679
Appears in Collections:[機械與機電工程學系] 研究計畫

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