一种基于频域的转动惯量估算方法

A moment of inertia estimation method based on frequency domain

描述了控制对象的两种等效数学模型,以第二种数学模型作为被控对象。引入了电流校正环节,建立了基于电流闭环的速度开环传递函数,推导了关于该速度开环传递函数的数学不等式,再将实际测得的幅频特性代入此不等式中,得到了关于转动惯量和机械时间常数的数学表达式。最后,以某光电测量设备的垂直轴作为控制对象进行了实验,用动态信号分析仪SR785测得实际系统的幅频特性,将该特性曲线上的某频率点代入到所建立的速度开环传递函数不等式中,得到转动惯量大于116.5590、小于116.6097;机械时间常数大于0.561587、小于0.561638。由此可见,这种基于速度开环频域特性估算系统转动惯量和机械时间常数的方法是相当准确的。

Two kinds of equivalent mathematic models are introduced, and the second kind of model is chosen as the controlled object. Current tuning is introduced, and the speed open-loop transfer function is established based on current closed-loop. A mathematical inequation about the speed open-loop transfer function is deduced, then the measured amplitude-frequency data is introduced in the inequation, thus the mathematic expressions about moment of inertia and mechanism time constant are obtained. An experiment was carried out taking the vertical axis of an electro-optic detecting equipment as the controlled object. A dynamic signal analyzer SR785 was used for measuring the amplitude-frequency property of the system. Then a certain frequency point on the feature curve was introduced in the transfer fimction inequation, and obtained that： 1） moment of inertia is greater than 116.559 0 and is smaller than 116.609 7 ; 2） mechanism time constant is greater than 0.561 587and is smaller than 0. 561 638. It shows that the method for estimating moment of inertia and mechanism time constant based on frequency domain feature of speed open-loop is quite exact.