JPH0356405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in angle measuring devices such as theodolites.

Conventionally, as a device for measuring angles without using a scale, for example, the USARMY Engineer
Topographic Laboratories Report ETL−TR
There is something reported in -72-1.

This angle measuring device measures the time T1 required for a slit provided on the circumferential surface of a constant-velocity rotating body to make one rotation with respect to a fixed reference point, and the time T1 required to rotate from that reference point to the angle measurement point. The time required for T2
The angle is determined by calculating 360 degrees x (T2/T1).

The angle measuring device as described above is characterized in that measurement is easy because it does not require a scale, and its configuration is also simple.

The report also mentions so-called 180-degree opposing readings to compensate for errors caused by eccentricity between the center of rotation of a constant-velocity rotating body and the center of rotation of an angle measurement point.

In the method described in the same report, the constant rotation performance of the rotating body in one rotation greatly affects the angle measurement accuracy. Therefore, in order to maintain high angle measurement accuracy, considerable care must be taken to ensure that the constant speed rotation performance of the motor driving the rotating body does not fall below a predetermined value.

If there is one period of uneven rotation during one rotation of the rotating body, the negative effect tends to be canceled by adopting 180-degree opposing reading. on the other hand,
As a result of our experiments using the method described in the same report, we found that in the feedback detection system for motor or rotation control, there are rotational irregularities of two or more cycles per rotation of the rotating body. Therefore,
In terms of angle measurement accuracy, there is a problem in that an error curve of these periods is drawn, and this error remains without being canceled even if 180-degree opposing reading is adopted.

The present invention has been made by focusing on the above-mentioned conventional problems, and is capable of correcting rotational unevenness of one or more cycles that occurs during one rotation of a rotating body, and also corrects eccentricity errors. The purpose of the present invention is to provide an angle measuring device that can perform

In order to achieve this object, the present invention includes a rotating body rotatably supported on a substrate via a rotating shaft, and a rotating body provided concentrically with the rotating body and rotatable relative to the rotating body. an angle measuring member; a rotary drive member fixed to the substrate for rotating the rotating body at a constant speed via the rotating shaft; a pair of reference points corresponding to the pair of reference points, which are provided on the angle measurement member on a straight line passing through its axis across the rotation axis thereof, and a pair of angle measurement points provided on the rotation body; a detection point that passes through a position opposite to the reference point and the angle measurement point, and detection means that respectively detects a time point at which the detection point passes the reference point and the corresponding angle measurement point. In the angle measuring device, the pair of reference points are provided at predetermined intervals, the number of which corresponds to the cycle of uneven rotation that occurs during one rotation when the rotating body is rotating at a constant speed, and each of the pair of reference points is A corresponding number of the pair of angle measurement points are provided at a predetermined interval, and further, when the rotating body is rotating at a constant speed, each of the detection points is detected by the detection means to detect one rotation with respect to the reference point. and a time T2 for each of the detection points to pass between each of the reference points and the corresponding angle measurement point;
From the above-mentioned at least one measurement time T1 and the average time T2 of the above-mentioned plurality of measurement times T2, the formula,
The present invention is characterized by comprising angle calculation means for calculating the angle that the reference point and the angle measurement point make with respect to the axis based on T2/T1.

The present invention will be explained below based on illustrated embodiments.
FIG. 1 is a plan view showing one embodiment of the present invention, and FIG.
The figure is a longitudinal sectional view taken along the - line in FIG. 1. In this embodiment, an angle measuring device is shown in which two cycles of uneven rotation occur during one rotation of the rotating body.

The rotating body 1 has two parts fixed at a predetermined interval in the axial direction.
It is composed of two discs 1a and 1b. These disks 1a and 1b are fixed to the rotating shaft 1c of the motor 3 and rotate together. This motor 3 is
It is fixed to a substrate 2 which is a non-movable part of the angle measuring device.

The collimating arm 4 is located at the tip of the rotating shaft 1c.
It is rotatably supported coaxially with the rotating shaft 1c. A collimating telescope (not shown) is fixed to the collimating arm 4, and the collimating telescope and the collimating arm 4 are configured to rotate together so that their rotation angles match.

Further, on the substrate 2, there are reference points R1, R, which serve as the reference for angle measurement, on a concentric circle centered on the rotation axis 1c.
2, R3, and R4 are provided. Reference point R1,
R3 and R3, R4 are formed as a pair so that they can be read opposite each other. In other words, the reference point R1,
R3 and R3, R4 are each arranged on a straight line passing through the rotating shaft 1c. And each reference point R
1 to R4 are set at equal intervals in the circumferential direction, that is, at an angle of 90° with respect to the axis. These reference points R1 to R4 each correspond to a set of light emitting elements 9a provided at positions sandwiching one disc 1b.
and a light receiving element 9b. however,
In FIG. 2, light emitting elements 9a at reference points R1 and R4 are shown.
1 and 9a4 and the light receiving elements 9b1 and 9b4 are shown. Further, the light emitting elements 9a are each fixed to an L-shaped support plate 16 fixed on the substrate 2.

A slit SR serving as a detection point is provided on the outer periphery of one of the discs 1b constituting the rotating body 1 and extending toward the axis. This slit SR is
As the rotating body 1 rotates, the light passes through (traverses) the optical path between the light emitting and light receiving elements 9a and 9b of each set.
Therefore, the light receiving element 9b outputs a signal (pulse) when the slit SR passes.

On the other hand, the collimating arm 4 consists of cross-shaped angle measurement arms 41, 42, 43, and 44 that are orthogonal to each other.
Each reference point R1 to R is placed at the tip of each arm 41 to 44.
Angle measurement points M1, M2, M3, M4 corresponding to 4
is provided. Here, the angle measurement point M1,
M3 and M2, M4 each form a pair.

Each angle measurement point M1 to M4 is a reference point R1 to R4.
Similarly, each light emitting element 10a and a light receiving element 10b are configured as a set. However, in FIG. 2, the light emitting elements 10a2, 10a of the angle measurement arms 42, 44 constituting the pair of angle measurement points M2, M4 are shown.
4. Only the light receiving elements 10b2 and 10b4 are shown.
Each pair of light-emitting and light-receiving elements 10a and 10b at the angle measurement points M1 to M4 are fixed to the U-shaped portions at the tips of the angle measurement arms 41 to 44, and are fixed to the outer peripheral edge of the other disc 1b of the rotating body 1. They are facing each other with the two sides in between.

On the outer peripheral edge of the disk 1b, extending in the axial direction,
A slit SM is formed as a detection point.
Therefore, each light receiving element 10b outputs a signal (pulse) every time the slit SM passes.

Further, the slit SM and the slit SR are formed at the same position in the circumferential direction and the radial direction.

FIG. 3 shows an example of the circuit used in the above embodiment, and FIG. 4 is a time chart showing the signal waveforms of the main parts of FIG.

Here, in order to improve the measurement accuracy, counter reading (for example, the time it takes for the slit to move from a certain reference point to a certain angle measurement point, and other references that exist at positions symmetrical to that reference point with respect to the center of rotation) A method of taking the average of the time it takes to move from a point to another angle measurement point that is symmetrical to that angle measurement point with respect to the center of rotation is adopted, but the following explanation will be given for only one of them. That is, the following description assumes that only two reference points, R1 and R2, are used, and only two angle measurement points, M1 and M2, are used. When performing opposite reading, based on the following explanation, it is sufficient to further measure the reference points R3 and R4 and the angle measurement points M3 and M4, and after performing a predetermined calculation, take the average of both.

In FIG. 3, the R1 output signal and R2 output signal are the output signals of the light receiving elements 9b1 and 9b2 at the reference points R1 and R2, respectively, and the M1 output signal and M2 output signal are These are output signals of the light receiving elements 10b1 and 10b2 at the angle measurement points M1 and M2, respectively.

The RS flip-flop 5 is set by the R1 output signal and reset by the M1 output signal, and has a positive output at its non-inverting output terminal during the time the slit passes from the reference point R1 to the angle measurement point M1. It outputs pulses. on the other hand,
The RS flip-flop 6 is set by the R2 output signal and reset by the M2 output signal, and has a positive output at its non-inverting output terminal during the time the slit passes from the reference point R2 to the angle measurement point M2. It generates pulses.

In addition, D flip-flop 7 is a slit SR
receives the R1 output signal every time it passes the reference point R1, and the first R1 output signal and the second
A pulse is output during the period between the R1 output signal, that is, one rotation time of the rotating body 1. While this pulse is being output, the AND circuit 13 is open,
A counter 33 is adapted to count clock pulses.

The clock generating circuit 20 generates clock pulses of a predetermined frequency. AND circuit 11
is to pass the clock pulse while the non-inverting output terminal of the RS flip-flop 5 is outputting a pulse, and the passing pulse is sent to the counter 3.
1 counts. Further, the AND circuit 12 is connected to the RS
While the non-inverting output terminal of the flip-flop 6 is outputting a pulse, a clock pulse is passed therethrough, and a counter 32 counts the passing pulses.

The microcomputer 40 has a counter 31,
It reads the contents of 32, adds them, and divides by 2, and the time obtained by this is T2
shall be. That is, the microcomputer 40
The time T2 is determined by averaging the pulse widths of the pulses that are the output signals of the counters 31 and 32. In addition, microcomputer 4
0 reads the output of the counter 33, sets the time to T1, and calculates 360 degrees x (T2/T1). The result of this calculation becomes the angle measurement value.

Figure 5 shows that when the angle is measured as described above,
It shows the principle of compensating for measurement errors at that time. For example, it is an error curve obtained by measuring an included angle of 90 degrees at each position of the theodolite. Here, the solid line curve is the error curve (fourth
In the figure, the error curve when using only two signals, the R1 output signal and the M1 output signal)
It is. In addition, the broken line curves in the figure are R2, M2
This is an error curve when measuring using the output signal.

By the way, the embodiment shown in Figs.
The measurement is performed by adding the solid line error curve and the broken line error curve in the figure, and the phases of these two curves are 90 degrees out of phase. For this reason, when the angle formed by one angle measuring arm 4 and another angle measuring arm 4 is set to 90 degrees, the error can ideally be reduced to zero.

From the solid line error curve shown in FIG. 5, it is possible to know the situation of rotational unevenness in the rotating body 1, and in this case, two periods of rotational unevenness occurred during one rotation of the rotating body 1. In response to this rotational unevenness, two periods of rotational unevenness (characteristics indicated by broken lines in FIG. 5) having opposite characteristics are provided. In order to provide this two-cycle rotational unevenness, the angular interval between the reference points R1 and R2 is set to 90 degrees.

Specifically speaking, while the rotating body 1 rotates once,
Assuming that there is rotational unevenness of n cycles, the angular interval between one reference point and the reference point next to it is 360 degrees/
(2×n) is most effective. Further, in that case, the number of required reference points and angle measurement points is n, respectively. In addition, in order to perform 180-degree facing reading, the number of reference points and angle measurement points is
Each of the above numbers is doubled.

That is, in general, it is sufficient to set the number of reference points and the mutual angular interval according to the period of uneven rotation that occurs when the constant velocity rotating body 1 makes one revolution; The number of angle measurement points can be set by Then, one set is formed of one reference point and one angle measurement point, a pulse is generated for each set, and the time T2 is determined by averaging the pulse widths of these pulses.

In the embodiment of FIG.
2 is provided. These two counters 3
1 and 32 are for measuring the pulse width of each of the RS flip-flops 5 and 6 simultaneously (in parallel).The advantage of providing two counters in this way is that the measurement time is shortened. There is. By the way, if the measurement time can be a little longer, the two counters 31 and 32 can be replaced with one counter 34, as shown in FIG. However, in this case, the multiplexer 50 is required.

That is, first, the RS flip-flop 8 is operated by the R1 output signal and the M1 output signal,
A counter 34 counts the pulse width via the AND circuit 14. This count value is stored in a predetermined memory. Next, in response to a switching control signal from the microcomputer 40, the multiplexer 50 selects the R2 output signal and the M2 output signal.
Then, via the AND circuit 14, the counter 34
counts the pulse width. This count value and
Add the value stored in the memory above and divide by 2, and set this value as T2. By dividing this T2 by T1, which is the time for one revolution, and multiplying by 360 degrees, you can obtain the angle measurement value.

Furthermore, a switching control signal from microcomputer 40 causes multiplexer 50 to select the first signal combination. In this way, these operations are repeated. In the above case, each pulse count is performed by rotating the rotating body 1 at a constant speed. In addition, in this embodiment, the rotation of the rotating body 1 is continued at a constant speed, and each of the above-mentioned pulses is continuously counted, and a plurality of T1 and T2 data are accumulated, so that the angle can be determined with higher precision. can be measured.

As described above, the present invention obtains more angle data per rotation than conventional angle measuring devices, and uses the rotation unevenness information for angle measurement. This angle data includes not only rotation unevenness information but also information on eccentricity between the rotation center and the rotation center of the angle measurement point. By the way, as shown in FIG. 5, the present invention cancels the error by adding opposite characteristics to each other, so the eccentricity error mentioned above is additionally corrected, which has the advantage of further improving measurement accuracy. There is.

Here, one set was made up of the reference point R1 and the angle measurement point M1, and one set was made up of the reference point R2 and the angle measurement point M2, but by changing these combinations. Good too. If the combination is changed, it is necessary to correct the obtained time T2 when calculating the time T2.

As described above, the present invention can sufficiently correct rotational unevenness in one rotation of a rotating body, and also correct errors caused by eccentricity between the rotation center of the rotating body and the rotation center of the angle measurement point. ,
This has the effect that highly accurate angle measurement can be performed.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, and FIG.
The figure is a vertical sectional view taken from the - line in Figure 1, Figure 3 shows an example of the circuit used in the above embodiment, Figure 4 is a time chart of the above embodiment, and Figure 5 shows a time chart of the above embodiment.
The figure shows the principle of the invention, and FIG. 6 is a circuit diagram showing another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Rotating body, 1a, 1b... Disk, 2... Board, 3... Motor, 4... Collimation arm, 5, 6...
...RS flip-flop, 7...D flip-flop, 31, 32, 33, 34...counter, 4
0...Microcomputer, R1, R2, R
3, R4...Reference point as detection point, M1, M
2, M3, M4... angle measurement points as detection points,
SR, SM...Slit as the detected part.

Claims (1)

[Scope of Claims] 1. A rotating body rotatably supported on a substrate via a rotating shaft; and an angle measuring member provided concentrically with the rotating body and rotatable with respect to the rotating body. , a rotational drive member fixed to the substrate and rotating the rotating body at a constant speed via the rotation shaft; and a pair of standards provided on the substrate on a straight line passing through the axis of the rotation shaft across the rotation shaft. a pair of angle measurement points corresponding to the pair of reference points, which are provided on the angle measurement member on a straight line passing through its axis across the rotation axis; An angle measuring device comprising: a detection point that passes through a reference point and a position facing the angle measurement point; and detection means that detects when the detection point passes through the reference point and the corresponding angle measurement point, respectively. , A number of the pair of reference points is provided at a predetermined interval, the number of which corresponds to the cycle of uneven rotation that occurs during one rotation when the rotating body is rotating at a constant speed, and a number of reference points corresponding to each of the pair of reference points is provided. The pair of angle measurement points are provided at a predetermined interval, and when the rotating body is rotating at a constant speed, the time T1 required for each of the detection points to make one rotation with respect to the reference point is detected via the detection means. and a time measuring means for measuring the time T2 during which each of the detection points passes between each of the reference points and the corresponding angle measurement point; Angle calculation means for calculating the angle formed by the reference point and the angle measurement point with respect to the axis based on the formula T2/T1 from the average time T2 of the measurement time T2; angle measuring device. 2 In claim 1, the angular interval between the reference point and the adjacent reference point is set to 360°/(2 ×n), and is provided with n each of the pair of reference points and the pair of angle measurement points (n≧2).