JPS6031011A - Angle measuring device - Google Patents

Abstract

PURPOSE:To make it possible to correct irregular rotation and to correct errors due to the eccentricity of angle measuring points, by providing a plurality of pairs of reference points and detecting points in one rotation of a rotary body, generating pulses corresponding to the passed time for every pair, and averaging the widths of the pulses. CONSTITUTION:In one rotation of a rotary body 1, a plurality of pairs of reference points and detecting points M1 and R1, M2 and R2... having an equal angular interval are provided. In correspondence with the detection of slits SR and SM of the rotary body 1 by both points, the pulses having the widths corresponding to the passed time between both points are outputted. The pulse widths are logically processed by a microcomputer and averaged. Then the irregular rotation and errors due to the eccentricity of the angle measuring points can be corrected. Thus the rotary angle can be measured highly accurately.

Description

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

Conventionally, devices for measuring angles without using a scale include:
For example, U, S, ΔRVj Y E nglneerT
R of opographic 1 laboratories
There is something reported in eport ETL-TR-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 for a slit provided on the circumferential surface of a constant-velocity rotating body to rotate once from that reference point to an angle measurement point. Considering the time T2 required for 360 degrees
The angle is calculated by calculating TI>.

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

The same report also mentions so-called 180-degree opposing reading in order to compensate for errors due to eccentricity between the rotation center of the constant velocity rotating body and the rotation center of the 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 that drives the rotating body does not fall below a predetermined value.

If there is one period of rotational unevenness during one rotation of the rotating body, the adverse 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 rotational irregularities of 2 or 3 cycles or more exist for one rotation of a rotating body in the feedback detection system for motor or rotational control. Therefore, there is a problem in the angle measurement accuracy that an error curve of these periods is drawn, and this error remains without being canceled even if 180-degree facing reading is adopted.

The present invention has been made by focusing on the above-mentioned conventional problems, and is capable of correcting the rotational irregularity of multiple cycles that occurs during one rotation of the rotating body, and the rotation center of the angle measurement point is eccentric. The object of the present invention is to provide an angle measuring device capable of correcting errors caused by this.

In order to achieve this objective, the present invention provides that a constant velocity rotating body is
Set the number of reference points and mutual angular interval according to the period of uneven rotation that occurs when rotating, set the number of angle measurement points according to the number of reference points, and set the number of reference points and angle measurement points. Each set constitutes a set, and a pulse is generated for each set,
By averaging the pulse widths of these pulses, the time T
2. In other words, if there is uneven rotation of n cycles during one rotation of the rotating body, the angular interval between one reference point and the reference point next to it is 360 degrees/(2x
n), and the number of reference points and angle measurement points at that time is set to n, respectively. Further, one set is made up 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.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. FIG. 1 is a plan view showing an embodiment of the present invention,
FIG. 2 is a longitudinal cross-sectional view taken along the line ■--■ in FIG. 1.

The rotating body 1 is composed of two discs 1a and 1b, which are rotated at a constant speed by a motor 3 via a rotating shaft 1C, and the rotating shaft 1G is a substrate that is a non-movable part of the angle measuring device. It is pivoted on 2.

The rotation axis of the reference arm 4 is set to exactly coincide with the rotation axis 1C. A reference telescope (not shown) is fixed to this reference arm 4, and the angle of the reference telescope and #! The angle of the quasi-arm 4 is made to match.

Further, on the substrate 2, there are reference points R1°R2,
R3 and R4 are provided, and each of these reference points R1 to R4 has a pair of a light emitting element and a light receiving element 5-. Further, a slit SR facing in the radial direction of the rotating shaft 1G is provided on the outer circumferential portion of the disc 1b constituting the rotating body 1, and as the rotating body 1 rotates, the slit SR is formed at the reference points R1 to R4. The light passes through an optical path from the light emitting element constituting the light emitting element to the light receiving element. When the slit SR passes through these optical paths while the rotating body 1 is rotating, each light receiving element generates a pulse.

The angular interval between adjacent reference points R1 to R4 is set to about 90 degrees.

On the other hand, the reference arm 4 has the same number of angle measurement points M1 to R4 as the reference points R1 to R4. M2. M3. M4 is provided. These angle measurement points M1 to M4 include reference points R1 to R4.
Similarly to each of the above, a set of a light emitting element and a light receiving element is provided.

These light-emitting elements and light-receiving elements face each other with the disc 1a in between, and each time the slit SM provided in the disc 1a passes through the angle measurement points M1-M4,
A pulse is generated in each of 4. Angle measurement point M
The angular spacing between adjacent parts 1 to M4 is set to about 90 degrees.

Further, the slits SM and SR are located 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 readings (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 opposing reading, based on the following explanation, further reference points R3, R4, angle measurement point M3. It is sufficient to measure M4 as well, 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 element at the reference points R1 and R2, respectively, and the M1 output signal and M2 output signal are the output signals at the angle measurement point. M1. These are the output signals of the light receiving elements in each of M2.

The RS flip 70 knob 5 is set by the R1 output signal and reset by the M1 output signal, and applies a positive pulse to its non-inverting output terminal during the time the slit passes from the reference point R1 to the angle measurement point M1. This is what is output. On the other hand, the RS flip-flop 6 is set by the R2 output signal and reset by the M2 output signal, and outputs a positive pulse to its non-inverting output terminal during the time the slit passes from the reference point R2 to the angle measurement point M2. is generated.

Further, the D flip 70 knob 7 receives the R1 output signal every time the slit SR passes the reference point R1,
Between the first R1 output signal and the second R1 output signal,
That is, pulses are output during one rotation of the rotating body 1. While this pulse is being output, the AND circuit 13 is open and the counter 33 counts the clock pulses.

The clock generation circuit 20 generates clock pulses of a predetermined frequency. The AND circuit 11 allows a clock pulse to pass while the non-inverting output terminal of the RS flip 70 tube 5 is outputting a pulse, and the counter 31 counts the passing pulse. Further, the AND circuit 12 allows the clock pulse to pass while the non-inverting output terminal of the R87 lip 70 tube 6 is outputting a pulse, and the counter 32 counts the passing pulse.

The microcomputer 40 reads the contents of the counters 31 and 32, adds them, and divides by 2.
The time obtained by this is called T2. That is, the microcomputer 40 calculates the time T2 by averaging the pulse widths of the pulses that are the output signals of the counters 31 and 32. Further, the microcomputer 4o reads the output of the counter 33, sets the time as T1, and
This is to calculate 0 degrees x (T2/TI). The result of this calculation becomes the angle measurement value.

Figure 5 shows the principle of compensating for measurement errors when measuring angles as described above. be. Here, the solid line curve is the error curve of the conventional device (in Fig. 4, the R1 output signal and the M1 output signal
This is an error curve when only two signals are used: the output signal and the output signal. In addition, in the figure, the broken line curve is R2
This is an error curve when measured using the °M2 output signal.

By the way, in the embodiments shown in Figures 1 to 4, measurements are made by adding the solid line error curve and the broken line error curve in Figure 5, 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 set to zero -10.

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, if there is rotational unevenness of n cycles during one rotation of the rotating body 1, the angular interval between one reference point and the reference point next to it is set to 360 degrees/(2xn). is the most effective. Further, in that case, the number of required reference points and angle measurement points is n, respectively. In addition, 18
To perform 011 facing reading, the number of reference points and angle measurement points is each twice the above number.

That is, in general, the number of reference points and the mutual angular interval may be set according to the cycle of uneven rotation that occurs when the constant velocity rotating body 1 makes one rotation, and 11 - the number of reference points. The number of angle measurement points may be set according to the following. 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. 3, counters 31 and 32 are provided. These two counters 31 and 32 are RS
This is to measure the pulse width of each of the flip 70 knobs 5.6 at the same time (in parallel).
Providing two counters has the advantage that measurement time is shortened. However, if the measurement time can be a little longer, one counter 3 may be used instead of the two counters 31 and 32, as shown in FIG.
It can be replaced with 4. However, in this case, the multiplexer 50 is required.

That is, first, the RS flip-flop Otub 8 is activated by the R1 output signal and the M1 output signal, and the counter 34 counts the pulse width via the AND circuit 14. This count value is stored in a predetermined memory. Next, micro combi coater 4
The multiplexer 50 selects the R2 output signal and the M2 output horn signal according to the switching control signal from 0. And A
A counter 34 counts the pulse width via the ND circuit 14. This count value and the value stored in the memory are added and divided by 2, and this value is set as T2. By dividing this T2 by T1, which is the time for one round, and multiplying by 360 degrees, the angle measurement value can be obtained.

Furthermore, a switching control signal from microcomputer 40 causes multiplexer 50 to select the first signal combination. In this way, rehearse these movements.

In the above case, each pulse count may be performed when the rotating body 1 rotates. Further, in the above embodiment, the rotating body 1 is rotated many times, and T1. It is also possible to measure the angle with high precision by accumulating T2 data in a hardware manner.

As described above, the present invention obtains angle data more times in one rotation than in the case of 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 errors by adding mutually opposite characteristics, so that correction for the eccentricity error is additionally performed, 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 distorted, 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. 14- It has the effect of being able to perform highly accurate angle measurement.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one embodiment of the present invention, and Fig. 2 is a plan view showing an embodiment of the present invention.
A vertical cross-sectional view taken from the line ■-■ in the figure, FIG. 3 shows an example of the circuit used in the above embodiment, FIG. 4 is a time chart of the above embodiment, and FIG. 5 is the principle of the present invention. FIG. 6 is a circuit diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Rotating body, 1a, 1b...Disk, 2...Substrate, 3...Motor, 4...Reference arm, 5.6...
RS flip 70 tube, 7...D flip flop,
31, 32. 33, 34... Counter, 40... Microcomputer, R1, R2, R3, R4... Reference point as a detection point, Ml, M2. M3. M4...Angle measurement point as a detection point, SR, SM...Slit as a detected part. Patent applicant: Asahi Optical Industry Co., Ltd. Agent: Kunio Miura 15-

Claims (2)

[Claims] (1) Time T1 required for the detected part provided on the circumference of the constant velocity rotating body to rotate once with respect to a fixed reference point
and the time T2 required to rotate between the reference point and the angle measurement point, and calculate the angle to be measured by calculating 360 degrees x (T2/TI >). The number of the reference points and the mutual angular interval are set according to the period of uneven rotation that occurs when the fast rotating body makes one revolution, and the number of the angle measurement points is set according to the number of the reference points. , the reference point and the angle measurement point constitute one set, a pulse is generated for each set, and the pulse widths of these pulses are averaged to calculate the time T2.
An angle measuring device characterized by a (2) In the above claims, the angular interval between one reference point and the adjacent reference point is set to 360 degrees/(2
xn), and the number of reference points and angle measurement points at that time is set to n, respectively.