SU1483254A1 - Instrument for determining coordinates of member position - Google Patents

Abstract

The invention relates to the field of measurement technology and can be used to measure small linear and angular displacements. The purpose of the invention, a simplification of the device, is achieved by using the same array of photodetectors when measuring the position in two coordinates due to the fact that the cross-shaped radiation source is located at an angle relative to the axis of symmetry of the photodetector array. The autocollimation optical system 2 forms an image of a cross-shaped radiation source 3 on a matrix of 4 photodetectors, whose position is determined by the angles of rotation of the mirror 1 associated with the object. Switch 5 performs line-by-line reading of the signal from matrix 4. Using the correlator 6 and the amplitude comparator 7, the column number is determined, in which the signal magnitude is changed, according to the number of which the measured value is recorded in relative coordinates using the counter 8. Similarly, the position of the object is recorded at another coordinate, where the reading is carried out in columns. 1 hp f-ly, 5 ill.

Description

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The invention relates to a measurement technique and can be used to measure small linear and angular displacements.

The purpose of the invention, the simplification of the device, is achieved by using the same array of photodetectors when measuring the position in two coordinates due to the fact that the cruciform radiation source is located under

fragile relative to the axis of symmetry of the array of photodetectors.

FIG. 1 shows the principle of operation of the autocollimation optical system; in fig. 2 — photodetector array and an autocollimation image of a cross-shaped radiation source; in fig. 3 is a matrix of photodetectors, on which photodetectors are shown by hatching, at the output of which a signal is present; in fig. 4 is a block diagram of the device; in fig. 5 - timing charts of signals at different points in the block diagram of the device.

The device includes a mirror 1 associated with the object, an autocollimation optical system 2, a cruciform radiation source 3 and a rectangular matrix of 4 photodetectors placed in the focal plane of the autocollimation optical system 2, switch 5, correlator 6, amplitude comparator 7, counter 8 and control unit 9.

Consider the operation of the device using the example of determining the coordinates of the angular position of an object. In this case, the optical connection of the matrix and the radiation source is carried out using an autocollimation optical system, the principle of which is explained in FIG. one.

FIG. Figure 1 shows a mirror 1 associated with an object whose angular position is to be measured. The possibility of rotation in the corners of the air conditioner is conventionally shown by placing the mirror 1 in the axles of the suspension. Mirror 1 is in the field of view of the autocollimation optical system 2 (shown conventionally), in the focal plane of which a cruciform radiation source 3 and a matrix of 4 photodetectors are placed.

The light flux of source 3 passes through the autocollimation optical system 2 and hits mirror 1. The reflected light of the mirror 1 again passes the light flux through the autocollimation optical system 2 and enters the matrix 4 of photodetectors, on which the autocollimation image of a cruciform radiation source 3 is formed (it is conventionally shown cross). When the mirror 1 rotates at the corners of the air, the image of the source 3 will move along the matrix 4 in the horizontal and vertical directions, respectively.

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FIG. Figure 2 shows an enlarged view of a matrix of 4 photodetectors and an autocollimation image of a cross-shaped radiation source.

Consider one of the lines of the cross, such as vertical. The interaction of this line with the rectangular matrix at their mutual rotation through the angle cp is equivalent to the interaction of the line without the rotation with the matrix made in the form of a transverse grid, i.e. when the line is moved, the signals in the photodetectors will appear sequentially in each row and By the row number in which the column number changes, you can judge the rotation angle. In this case, the resolution will be determined by the ratio of the size of the photodetector a to the number of / V rows.

At different values of the angle f, the resolution is obtained. The resolution change occurs discretely at such angles of f, at which the cross line is parallel to the diagonal of one or several columns of the matrix.

It is advisable to choose the tangent of the rotation angle by a multiple of the distance between the rows or columns of the matrix to the length of the row or column, i.e.

,

where K -1,2, S ... L / (M);

a is the distance between rows (columns);

b - the length of the row (column); N (M) is the number of rows (columns).

When / (1, the maximum resolution is reached, is equal (in the case of angular measurements)

& a j-arctg-: -f

(2)

where / is the focal length of the lens.

Similarly, you can determine the angular position of the object in another coordinate.

The switch 5 reads the signals from the photodetectors of the array in two steps successively in rows and columns. The correlator 6 compares the signal sequence of the rows or columns with the reference signal S (t). The amplitude comparator 7 compares the signal from the correlator 6 with the threshold level (Run. The pulse counter 8 counts the pulses of the control unit 9 from the moment the signals from the photodetectors start reading in rows or columns until it stops by the signal from the amplitude comparator 7 and thereby registers ( in relative units) the magnitude of the angular displacement.

The operation of the registration scheme is illustrated by the timing diagrams shown in FIG. five.

To determine the coordinate a, the switch 5 reads the signals from the photodetectors of the matrix 4 in columns, starting with the first one in the direction of the arrow in the figure of FIG. 3 (top to bottom). Moreover, for this configuration, the sequence of signals of this coordinate 5a has the form shown in FIG. 5. In the correlating torus b, a one-by-one multiplication of the signal Sa with the signal S (t) occurs and the results of the multiplication are summed up. The result is the signal Ska- At the moment ta, the signal reaches a maximum, and the time from the beginning of the reading to the moment ta is proportional to the coordinate a. Since the read pulses from the control unit 9 run at regular intervals of time, the coordinate a is proportional to the number of read pulses produced by the instant a. The moment (and is determined by the amplitude comparator 7, which generates a signal at the moment when the maximum signal is reached by Sfca. Since the pulse counter is started at the moment of starting reading, and is stopped by the signal from the comparator 7, the readings / Va of the counter 8 pulses are proportional to the coordinate a.

The coordinate p is determined in a similar way, and the reading takes place along the rows of the matrix, starting with the first one in the direction of the arrow shown in FIG. 3 (from left to right).

All the above concerns the case of measuring angular deviations, however this is also true for the case of measuring

five

shifts, thereby changing the type of optical coupling between the radiation source and the matrix.

Claims (2)

1. A device for determining the position coordinates of an object, comprising a cruciform radiation source associated with the object, a rectangular array of photoreceivers installed along the light beam, and a recording circuit connected to a rectangular matrix, in order to simplify the device by using the same matrix for measuring the position in two coordinates, the registration scheme is made in the form of a serially connected switch, correlator, amplitude comparator and counter block control, whose first input is connected to the control input of the switch and the other - to the control input of the counter, the source of radiation and a matrix of photodetectors are deployed so that the symmetry axis of the matrix of photodetectors and radiation side istochni5 ka form an acute angle. 2. The device according to claim 1, characterized in that the tangent of the angle formed by the axis of symmetry of the matrix and the side of the radiation source is chosen to be a multiple of the ratio of the distance between the rows or columns of the matrix to the length of the row or column. 0 tt FIG. one FIG. 2 I I IJI lennsen J P . I, L., Column / column 5sthl6ts Threshold, S b FIG. five 1 2 3 C 5 But feather column FIG. 3 J P . I, L., I L, t   / column 5sthl6ets horn, L, i L. line 5 line