中文摘要：

研究了被控对象包含密集模态时对控制的影响,说明了密频系统的模态不稳定特性引起对象模型不准确,给控制器设计造成困难并容易导致控制性能下降。分析了已有的密集模态定义及相关判别准则的不足,针对控制,从密集模态振型不稳定性角度提出了新的基于振型灵敏度的密集模态界定方法,容易辨别出系统的密集模态子集,也可以用于比较不同系统的模态密集程度。算例表明,该方法准确有效,以此界定模态密集程度对振动控制更有意义。

英文摘要：

Mode shape errors can be large in flexible space structures comprising closely clustered modes of vibration,because it arises from very small manufacturing errors.If not properly taken into account,this so called ＂unstable modes＂ will potentially pose problems for high-performance flexible spacecraft controllers based on nominal models.With this understanding,it was analyzed that former definitions of close modes were limited.This paper prompted a new way,based on mode shape sensitivity to structure parameters,to define close modes,which emphasized the impacts of close modes on control.It was shown that this new measurement could be used to compare the density of clustered modes comprised in two different structures.An example computational study showed that this measurement was accurate and effective.