SU1216733A1 - Meter of object movement - Google Patents

Abstract

The device relates to measurement technology and can be used for non-contact measurement of the speed of extended objects. The purpose of the invention is to increase the accuracy of measuring the speed of an extended object. The extended object 15 moves at different speeds in the direction from the first photodetector to the second, and parts of surfaces with different brightness pass through their fields of view. The signals at the output of amplifiers 3 and 4 vary in proportion to the brightness of the surface areas of the object that fall within the field of vision of the photo-detectors. The conversion of the fct value measured by the meter 9 into the object velocity is performed by calculating the reciprocal of bt using the converter 14. 2 Il. g (l fuff

Description

The invention relates to a measurement technique and can be used for contactless measurement of the speed of extended objects, for example, the underlying surface.

The aim of the invention is to improve the accuracy of measuring the speed of an extended object.

On the block diagram of the proposed device; figure 2 is a plot of the signals at the outputs of individual elements of the device.

The device contains two photodetectors (AF) i and 2, two amplifiers 3 and 4, subtraction unit 5, absolute magnitude detector 6, threshold device 7, pulse front detector 8, time meter 9, key 10, storage device (memory) 11 , comparator 12, detector of 13 pulse fronts, functional converter 1 / X 4.

On the moving object 15, the arrow indicates the direction of its movement E1 and E2 surface areas of the object falling into the field of view, respectively, of the first and second along the photoreceiver channels. The optical axes of the photodetectors 1 and 2 are oriented so that their fields of view E and E2 are in contact with the surface of the object 5 moving with speed. The outputs of both photoreceivers 1 and 2 are connected through amplifiers 3 and 4 to the inputs of subtraction unit 5. The output of the amplifier 3 is also connected to the input of kcha 10, and the output of the amplifier 4 to the input of the comparator 12. At the output of the subtraction unit 5, the serially connected absolute detector 6 is connected, the threshold device 7 and the front edge detector 8 of the impulse, whose output is connected to the first input (input start) measure 9 time interval ,, and to the control input of the key 10, the output kcha iO is connected to the input of the storage device 11, the output of which is connected to the second input of the comparator 12. The output of the comparator 12 through the detector 13 fronts is connected to rum entry (Bhodu stop) measurable 5tel slot 9, which is connected to the functional probrazovatelyu 1 / X 14o. Blocks I and 2 are point photodetectors, the signal

emnik 2 (E2) Nalya E

at the output of which is proportional to IJH– the integral brightness of the surface areas of the object (respectively Э1 and 32), I get into their field of vision of their optical systems. Blocks 3 and 4 are linear amplifiers. The subtraction unit 5 together with the absolute magnitude detector 6 serves to generate a signal proportional to the absolute value of the difference between the weights of the sections 31. and E2, i. Threshold device 7 generates a signal of a logical unit in the case when the signal at its output exceeds a certain threshold. The front edge detector 8 serves to form a short pulse along the leading edge of the pulse entering its passage. The storage device 11 serves to store the value of the analog signal arriving at its input through the key 10 at the moment the pulse key arrives at the control input from the output of the leading edge detector 8. The comparator 12 generates a logical zero signal when the signal at its first input is less than the signal at its second input and the signal of a logical unit when the signal at the first input is larger than the signal at the second input. The detector 13 of the fronts is used to form short pulses along the leading and trailing edge of the pulse coming from the comparison circuit 12. The meter 9 of the time interval 9 measures the time interval between the pulse arriving at its first input from the front-edge detector 8 and the pulse arriving at its second input from the detector of the 13 fronts. The functional converter is intended to convert the quantity X arriving at its input (the time interval to the reciprocal of the magnitude / X.

The device works as follows.

The extended object 15, whose speed varies, moves in the direction from the first photodetector to the second. Sections of the surface with different brightness alternately pass through the field of photo-photo- (E1) and photodetector. As a result, the signal i Ei at the output will increase3

Leagues 3 and 4 vary in proportion to the brightness of the surface areas of the object that fall within the field of view of the corresponding photodetectors. On figa, b, diagrams of the possible nature of the dependence of the signals E and E on time are presented as an example. The signal E4 (t) completely repeats the course of the signal Ej (t), but lags behind it by an unknown time interval determined by the known distance between the photoreceivers (base) and the measured velocity V of the object. Block 5 subtraction together with the detector 6 absolute magnitude produces the formation of a signal, -E4 | proportional to the absolute value of the difference in brightness of the surface areas of the object. The signal at the output of the detector 6 absolute values presented on figv. The threshold value & E of the threshold device 7 is shown here, the output signal of which is shown in FIG. This signal takes the value of a logical unit when the difference between the signals of photodetectors Е „and Е in absolute value exceeds the value of the threshold ЕД. The detector 8 of the leading edge of the pulse at the output of the threshold device 7 captures the time points (t, tj, t) when the absolute value of the difference between the signals of the photodetectors E and E becomes greater than the threshold value iE, producing at this moment a short pulse Eg shown in FIG. 2d Since the distance between the photodetectors d5 is known, this is equivalent to fixing the point in time when the quantity / E - E / uS, which is approximately equal to the spatial derivative of the object's brightness in the vicinity of the measured region, becomes equal to threshold value Le / iS. Impulse U (fig. 2d) from the front-edge detector 8 opens the key 10, as a result of which the memory device 11 stores the signal Е "(fig. 2e - flat line), equal to the value of the signal signal EZ in the first receiving channel during the movement time t ,, fixed detector 8 front of the front. On fig.2e the dotted line also shows the signal E (t), coming from amplifier 4 to the first input of the comparator 12, to the second input of which

16733

The signal E comes from the output of the memory 11. As shown in FIG. 2g, the signal at the output of the comparator 12 takes the values of a logical unit 5, when the signal E at one of its inputs is larger than the signal at its other input. Generates short pulses on the front and rear edges of the pulse coming from the output

10 of the comparator, the detector of the 13 fronts of the pulse fixes the moments of time when the signals E and E are equal (in Fig. 2 the moments tj, C, t), i.e. when the photoreceiver 15 of nick 2 is in the field of view, as a result of the object moving, the brightness of which is measured by the photodetector 1 at the preceding point in time, respectively, t ,, t, tj.

2Q The measurement of the time interval between the moments t, and t (t and t, tj and tg), carried out with the help of the time meter 9, allows to calculate the speed of movement

25 objects, like the & S / it ratio,

where S is the known distance between the photoreceivers I and 2, a is t (. ,, tf tf) Due to the fact that the value of g8 is fixed, pre, the formation of the value of the time interval At measured by the block 9 of the object is by calculating the value of the inverse At using a function converter 10 that performs operation 1 / X on the input signal X with the appropriate scale factor.

The considered meter can be made on the basis of existing standard analog and digital elements.

35

40

The converter / X can be implemented using a deLenin device - analog or digital, based on a nonlinear element having a hyperbolic amplitude characteristic. In the case where the input variable is convertible

(time interval} is represented in a digital code, the 1 / X converter can be quite simply made in the form of a transcoder implemented on elements of digital logic or a specially programmed memory device.

As a time line meter, it can be used.

S

For example, a timer implemented on the basis of a pulse counter and a clock pulse generator triggered by a start pulse and stopped by a pulse stop, or any other device that implements the function of measuring the time interval between pulses to its two inputs. The subtraction unit can be implemented on the basis of a differential amplifier, and an absolute magnitude detector can be implemented using a two-period rectifier circuit. A storage device with a key at the input can be implemented, for example, according to one of the schemes of the sampling-storage device.

Claims (1)

Invention Formula An object speed meter containing two photoreceivers dispersed along the object trajectory with amplifiers connected at their outputs, a comparator, a key connected in series and a memory device connected to one input of the comparator, the other 336 the input of which is connected to the output of the amplifier connected to the output of the second along the photodetector's movement, threshold devices, a detector of the leading edge of the pulse, connected in series to the time interval meter, and a functional converter at the output of the time meter, with In order to improve accuracy, a subtraction unit, an absolute magnitude detector and a front detector are added to it. pulses, while the inputs of the subtraction unit are connected to the outputs of the photodetector amplifiers, and the output is through an absolute magnitude detector to the input of the threshold device, the comparator output is connected to the first time interval meter through the edge detector, and the front edge detector output to the second time meter input and to the control input of the key, the input of which is connected to the output of the amplifier of the first along the photodetector movement.