在闭环控制系统中引入了扰动估计和补偿来改善光电稳定平台低速性能,并提高其扰动抑制能力.提出了基于速度信号的扰动观测器,并对其各项性能进行了研究.介绍了常规的基于加速度的扰动观测器的工作原理,指出了它在光电稳定平台应用中存在的问题;通过引入平台的标称模型,构建了基于平台速度信号的扰动观测器,给出了相应的闭环控制系统结构,分析了它的输入输出特性、扰动抑制能力和鲁棒性;最后,对本文方法进行了仿真和物理实验.实验结果表明:当平台按0.5 Hz,0.6(°)/s做正弦运动时,引入本文提出的带扰动观测器的PI控制基本克服了常规PI控制存在的低速爬坡现象;对于1 Hz,6.3(°)/s的载体正弦速度扰动,平台的扰动隔离度提高了约14 dB,稳定精度从0.03°(RMS)提高到了0.004 4°(RMS).实验结果证明了本文方法的有效性.%The disturbance estimation and compensation was introduced into close loop control systems to improve the low speed performance and disturbance rejected ability of photoelectric stabilized platforms. An original Velocity based Disturbance Observer (VDOB) was proposed and its characteristics were studied. The working principle of regular Disturbance Observer (DOB) was introduced and its drawbacks in applications to stabilized platforms were pointed out. By introducing a nominal model of stabilized platforms, the VDOB was established based on velocity signals, the structure of closed loop control system with VDOB was given, and its transfer behavior, disturbance rejected ability and robustness were analyzed. Finally, some simulations and experiments were carried out. Experiment results show that the PI controller with VDOB can overcome the speed creeping problem existed in traditional PI controllers when the platform does sinusoidal movement. Furthermore, the velocity disturbance isolation level of the platform after using PI controller with VDOB is increased by about 14 dB, Correspondingly, the stabilization precision of platform is increased from 0.03°(RMS) to 0. 0044°(RMS) when the vehicle on platform is moved in sinusoidal manner at 1 Hz and 6.3(°)/s. In conclusion, the proposed VDOB is effective and valuable.
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