SU819743A1 - Method of measuring linear system amplitude and phase frequency characteristics - Google Patents

Description

one

The invention relates to instrumentation technology and can be used to measure the amplitude and phase frequency characteristics of an AFC) linear systems, in particular for monitoring automatic control systems and their elements ...

Methods are known for measuring AFC, based on recording the response of a linear system to rH rmonic input action, determined by the measurement of the input and output signals iQ. Such methods have the following errors:

dynamic error of the second kind due to the finite measurement time of the instantaneous values of the signal ;.

a significant decrease in the measurement accuracy in the presence of constants: the components in the input 4 and the output signals;

the complexity of calculating the parameters of the input and output signals.

The closest technical solution to the invention is the method of controlling the AF of linear systems, based on the registration of the reaction

systems on a heUnial input action at instantaneous values of the input and output signals in a steady state mode, measured at three successive points in time at equal intervals, not exceeding one half the period of the established oscillations pQ. All those disadvantages correspond to this method.

0

The purpose of the invention is to improve the measurement accuracy.

For this purpose, four predetermined constant-reference signals are fixed — two for comparison with input 5 ”and one shaft and two for comparison of one-to-one signal that does not exceed the amplitude of the input and output signal and the output signal are compared with the reference amplitude and fixed

0 seven moments of signal equality times - two consecutive moments for each reference signal except for the fourth one, for

5 kole 4rogo fix one moment ra-. mines, time intervals, bounded by fixed moments, and by the values of the reference: signals and time intervals, you reach amplitude and phase

Claims (2)

0 frequency characteristics "and the frequency of the input signal. Fig. 1 is a functional block diagram of one of the possible devices implementing this method; figure 2 shows the timing diagrams of measurements. The device contains the object 1 control, the inputs of which are connected to the generator 2 harmonic signals / specifies the input signal Y, and the command sensor 3. The generator is connected via amplitude comparator 4 to the computing unit 5, to the second input of which through the amplitude comparator 6 is connected the output of object 1 The outputs of block 5 through digital-to-analog converters (D / A) 7 and 8 / forming reference signals Y-Y4 are connected to the second inputs of the comparators 4 and b, as well as to the control input of the generator 2. The method of control of AFCh is performed as follows in a way. According to the instructions of the computing unit 5, the generator 2 delivers a harmonic signal to the input of the control object 1 and to the measuring input of the comparator 4 (see Fig.2). The DAC 7 supplies the reference input of the comparator 4 orbital signal and the DAC signal supplies the reference signal to the reference input of the comparator 6 UZ In addition, the measuring input of the comparator 6 receives a signal from the test object. At the end of the transition process at the output of the control object 1, the computational unit 5 perceives the signals coming from comparators 4 and 6 at the moments of equality of the instantaneous values of the input and output signals to the reference signals (moments t - t Computing unit 5 remembers the moment of arrival of the signals of the comparators 4 and 5 and issues commands in the DAC 7 to change the reference signal Y2, and DAC B to change the reference signal Yj by 4. When the necessary information has been collected (times t - t), the computational unit 5 proceeds to its processing, calculated the circular frequency of its signals;, the phase shift 4 between the input and output signals of the amplitudes DY of the input Ygxfn and the output u, and the dynamic gain of the linear ss system C0: H HLH ti-ia 2t7-trt.2 C05CO-2COSGJ Y4 cosc-cosco illklk., - VYKhTP iv; r Thus, this method allows to reduce the dynamic measurement error by 2 n times, where n is the number of binary bits of the measured value (for peaJlnoy measuring instrumentation n 5), In addition, the method allows controlling automatic control systems as part of objects Without nullifying the command sensors, as well as eliminate the error of the metering caused by the constant component at the output of the control object. The invention The method of controlling the amplitude and phase frequency characteristics of linear systems, based on recording the response of the system to the harmonic input effect, determined by the instantaneous values of the input and output signals in a steady state, so that in order to improve the measurement accuracy, four pre-defined constant reference signals are formed — two for comparison with the input signal and two for comparison with the output signal, not exceeding the amplitude of the input and output signals; The input and output signals are considered with reference and seven times of equality of signals are recorded — two consecutive moments for each reference signal except for the fourth, for which one moment of equality is fixed, time intervals, limited by the fixed moments, are measured, and time intervals are calculated amplitude and phase frequency characteristics at the frequency of the input signal. Sources of information taken into account during the examination 1. USSR author's certificate 266936, cl. G 01 R 17/00, 1968. 2. Authors certificate of the USSR 237262, cl. G 01 R 37/28, 1967 (prototype).