时滞对非线性饱和控制减振频带漂移的影响

主要研究非线性饱和控制减振系统中由于内共振频率偏差引起的有效减振频带的漂移问题. 在该减振系统中分别考虑控制信号、反馈信号以及自反馈信号的时滞对振动系统有效减振频带漂移以及有效减振频带宽度的影响, 从而通过调节控制信号、反馈信号以及自反馈信号的时滞量, 来控制系统有效减振频带的漂移. 研究结果表明: (1) 在原始的无时滞减振系统中, 由于内共振频率偏差的存在, 使得系统的有效减振频带向主共振点的上、下两个方向漂移, 并且内共振频率偏差的绝对值越大, 有效减振频带漂移的程度也越大, 使得系统有效减振频带的分布不合理, 导致振动控制效果降低; 但是, 根据内共振频率偏差的变化, 可以通过适当调节控制信号和反馈信号的时滞, 或者也可以调节自反馈信号的时滞, 在消除有效减振频带漂移的同时又增大有效减振频带的宽度. (2) 内共振频率偏差的绝对值越大, 控制信号和反馈信号的时滞、或者自反馈信号的时滞对消除有效减振频带漂移以及增大有效减振频带宽度的作用越显著. 

EFFECTS OF DELAY ON EFFECTIVE BAND DRIFT IN NONLINEAR SATURATION CONTROL SYSTEM

For active control systems, all operations in the control process are not instantaneous. It implies that various delays exist inevitably in the real-time control systems. In fact, time delay in control system is derived from measurement of system states, caused by physical prosperities of the equipment used for control and transport delay, by performing on-line computation, filtering and processing data and by calculating and executing the control forces as required. Thus, effects of the delays in the designed controller should be considered since they cannot be eliminated even with the present technology. It should be noted that due to the complexity of the nonlinear dynamical system, most scholars studied the effect of delay on the control performance in the linear dynamical system. However, the effect of both nonlinearity and delay on dynamical behaviors of the system is very complex. The authors investigate the effective band drift due to internal resonance frequency deviation existed in the nonlinear saturation control system. The effects of delays in control, feedback and self-feedback signals on effective band drift and bandwidth are studied. Then, the effective band drift may be controlled by choosing appropriate delays. From the examples illustrated, in the original system without considering delays, the effective band may drift to the primary resonance point upward or downward when the internal resonance frequency deviation exists. Moreover, the greater the absolute values of internal resonance frequency deviation is, the greater the effective band will drift. The effective band drift can lead to the performance degradation of vibration suppression about the primary resonance point. However, the effective band drift can be eliminated by choosing appropriate delays of control, feedback and self-feedback signals according to the changes of internal resonance frequency deviation. Meantime, the effective bandwidth is broadened. Both analytical and numerical results show that the greater the absolute values of internal resonance frequency deviation is, the more effects of the delays on the effective band drift and bandwidth will be.