none Study of Balancing Balls on Tracking-Error Suppression for DVD Drives under Severe Vibratory Environment

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Title:	none Study of Balancing Balls on Tracking-Error Suppression for DVD Drives under Severe Vibratory Environment
Authors:	徐仕穎;Shih-ying Hsu
Contributors:	機械工程研究所
Keywords:	平衡滾珠;光碟機伺服控制;automatic ball balancer;DVD driver
Date:	2010-08-05
Issue Date:	2010-12-08 13:45:32 (UTC+8)
Publisher:	國立中央大學
Abstract:	車用的光碟機容易受到外界振動的干擾進而導致光碟片無法順利讀取，因此我們實驗室利用修正型適應性複合伺服控制器(MAHC)並結合RVSS-FXLMS來消除尋軌及聚焦的誤差，此方法在100 Hz以內的誤差有很好的消除效果，但依然不能使光碟機從不能讀取變成可以讀取，因此加上了被動式的吸震海綿之後，方可消除100 Hz以上的誤差，並且能使光碟機從不能讀取變成可以讀取，因此為了探討是什麼原因造成高頻的尋軌誤差，此研究利用實驗設計的方式探討真正的原因，並利用數值模擬來探討滾珠對於平衡主軸的有效範圍。 In a vehicular environment, the DVD drives are apt to be influenced by severe external vibration. Therefore, At our laboratory a modified adaptive hybrid servo controller (MAHC) associated with the robust variable step-size filter-x-least-mean-square (RVSS-FXLMS) was applied to eliminate the focusing and tracking errors at low frequencies from 0 Hz to 100 Hz. However, no matter how the tracking errors under 100 Hz frequency was suppressed, the DVD data-reading still failed since there existed errors at high frequencies. Hence, the sponge was added on the DVD drive to aid MAHC associated with RVSS-FXLMS to eliminate the tracking errors at higher frequencies from 100 Hz to 500 Hz, and then the DVD drive was able to read data well. At the beginning, to explore the causes to make tracking errors large at high frequencies, the balancing balls were suspected. However, this study used a series of experiments to explore exact reasons of the tracking errors at high frequencies. It is found that these errors are generated by structural resonance but not balancing balls on the DVD drive. On the contrary, the balancing balls play an effective role to resolve the unbalanced disk and spindle. In this study, the automatic ball balancer (ABB) dynamic motion equations are derived, and direct computer simulations are carried out. The simulated results confirm that the balancing balls are effective when the unbalanced disk or spindle is operated above the critical speed (ω/ωn=1). Therefore, if the spindle speed of the DVD drives is higher than the structural resonance frequency, the balancing balls will eliminate the tracking errors.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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