JPS608711A - Angle measuring device - Google Patents

Abstract

PURPOSE:To measure an angle with high precision and to make the device small-sized and to reduce the power by providing two reference points and two angle measuring points in an angle measuring device such as a theodolite or the like and selecting one angle measuring point and one refernce point, which are used for angle measuring operation, in accordance with relative positions between angle measuring points and reference points. CONSTITUTION:Pulses, which are generated when two slits provided at an interval of <=90 deg. pass two reference points R1 and R2 and two angle measuring points M1 and M2, are utilized to measure an angle. One of two points M1 and M2 is selected properly and used to perform a high precision angle measurement where the variance of rotation in two cycles in one rotation of a rotating body 1 is compensated. A selecting means of angle measuring points M1 and M2 consists of a means which detects a longer pulse interval t6 out of pulse intervals of a signal R1, a means which detects whether pulses p1 and p2 exist together in this interval t6 or not, and a means which uses the signal at the angle measuring point M2 as an M1 output signal if pulses p1 and p2 do not exist in the interval t6.

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, U, S, ARMY EnatneerTo
R of pographtcl aboratorles
There is something reported in eport ETL-TR-72-1.

This angle measuring device rotates from a fixed reference point to an angle measurement point, such as the time T1 required for a slit numbered on the circumferential surface of a constant velocity rotating body to make one rotation with respect to a fixed reference point. Considering the time T2 required to do this, 360'
2/ T 1 ) wo performance by tJtZr;
It adjusts the angle.

J: The angle measuring device described in 2 is characterized in that measurement is easy because it does not require a scale plate, and its construction is also simple.

The same report also mentions so-called 18° opposing reading in order to compensate for errors caused by eccentricity between the center of rotation of the constant velocity rotating body and the center of rotation of the angle measurement point.

In the method described in the same report, the constant speed rotation performance of the rotating body in one revolution 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 if 180° opposing reading is adopted. 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 two cycles of uneven rotation per rotation of the rotating body. Therefore, angle measurement 14
Even in the case of degrees, a result that draws an error curve of two periods occurs,
There is a problem that this error remains without being canceled even if 180° opposing reading is adopted.

The present invention has been made in view of the above-mentioned problems of the conventional art, and it is possible to correct the two-cycle rotational irregularity that occurs during one rotation of a rotating body without increasing the number of detection units and with a simple configuration. The purpose is to provide a device that can.

In order to achieve this objective, the present invention includes a detection portion of 9
It is composed of two slits provided at an angular interval of 0° or less, and two slits are provided each for the reference point and the angle measurement point, and the angle measurement is performed according to the relative position of the angle measurement point and the reference point. One angle measurement point and one reference point are each selected for use in calculation.

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, and FIG. 2 is a longitudinal cross-sectional view taken along the line ■--■ in FIG.

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 1G, and the rotating shaft 1c 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 substantially coincide with the rotation @1c. A reference telescope (not shown) is fixed to this pA quasi-arm 4, so that the angle of the reference telescope and the angle of the reference arm 4 match.

Furthermore, reference points R1°R2 are provided on the substrate 2, and each of these reference points R1 and R2 has a pair of a light emitting element and a light receiving element.

Furthermore, slits SR1 and SR2 are provided on the outer periphery of the disc 1b constituting the rotating body 1, and are oriented in the radial direction of the rotating shaft 1C. The light passes through an optical path from the light emitting element to the light receiving element forming points R1 and R2. When the slits SR1 and SR2 pass through these optical paths while the rotating body 1 is rotating, each light receiving element generates a pulse. What are slits SR1 and SR2?9
They are installed at intervals of 0° or less.

On the other hand, at both ends of the reference arm 4, there are angle measurement points M1. M
2 is provided. These angle measurement points M1. Similar to the reference points R1 and R2, M2 is provided with a set of a light emitting element and a light receiving element, respectively.

These light-emitting elements and light-receiving elements face each other with a disk 1a in between, and slits SMI and S are provided in the disk 1a.
M2 is the angle measurement point M1. Each time M2 is passed, the angle measurement point M1. A pulse is generated at M2. Slit SM
I and 8M2 are installed at an interval of 90 degrees or less.

Further, slits SM1 and SR1 are located at the same position in the circumferential direction and radial direction, and slits SM2 and SR2 are also located at the same position. Note that the exact values of the angular interval between the slits SM1 and SIv'12 and the angular interval between the slits SM2 and SR2 do not need to be known.

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, to improve the measurement accuracy, it is important to consider the time required for a slit to move from one reference point to the next angle measurement point (for example, the time it takes for a slit to move from one reference point to the next angle measurement point), and the time it takes for a slit to move from the remaining reference points to the remaining angle measurement points. However, the following explanation will be given for only one method.
Each disk 1a.

Although two slits are used for each 1b, the explanation will be made assuming that only R1 is used as a reference point and only Ml is used as an angle measurement point. When performing facing reading, further check the reference point R2 and the angle measurement point M based on the following explanation.
2 may also be measured, and after performing a predetermined calculation, the average of the two may be taken.

In FIG. 3, the R1 output signal is the output signal of the light receiving element at the reference point R1, and the M1 output signal is the output signal of the light receiving element at the angle measurement point M1. The measurement start signal is a signal output from a microcomputer or the like to start angle measurement.

The D flip-flop 5 divides the R1 signal by one stage while receiving the measurement start signal, and the D flip-flop 6 similarly divides the M1 signal by one stage.

In addition, the RS flip 70 knob 7 is set at the rising edge of the non-inversion ratio horn No. 13 of the D flip-flop 5,
It is reset at the rising edge of the non-inverting J signal of the D flip 70 knob 6. Furthermore, the RS flip-flop (NIL) is set by the rising edge of the inverted output signal of the D flip-flop 5, and the D flip-flop 6
It is reset by the rising edge of the inverted output signal. Further, the RS flip-flop 9 is set by the rising edge of the inverted output signal of the D flip-flop 5, and reset by the rising edge of the non-inverted output signal of the D flip-flop 70/knob 6.

The D flip-flop 10 inputs the non-inverted output signal of the D flip-flop 5 and outputs a pulse for the time until the slit SRI passes, that is, the time for one rotation of the rotating body 1.

The frequency divider circuit 12 divides the clock signal from the clock generation circuit 11 (hereinafter referred to as "normal clock signal") by one stage, that is, half of the clock signal output by the clock generation circuit 11. It outputs a clock signal with a frequency of (hereinafter referred to as "half clock signal").

However, instead of the frequency divider circuit 12, a clock generation circuit that generates half the clock signal from the beginning may be used.

The NOR circuit 21 inputs the non-inverted output of the RS flip-flop 7 and the non-inverted output of the RS flip-flop 8, and outputs a signal having a time width from the left end of t4 to the right end of t5 in FIG. It is something to do.

AND circuit 22 combines half the clock signal and NOR circuit 2.
1 and the inverted output of the RS control flop 9, and allows half of the clock signal to pass during the total time of tl and t2 in FIG. In other words, when tl and 12 in FIG. 4 are present, the same thing is done as if a normal clock signal were output at half of one hour.

The AND circuit 23 connects the output of the clock generation circuit 11 and the RS
The flip 70 receives the inversion ratio j of the knob 9, and passes a normal clock signal during the time 13 in FIG.

The NOR circuit 24 receives each output of AND circuit #22 and #23, and receives the half clock signal generated at the time tl and t2 in FIG. 4, and the normal clock signal generated at t3 in FIG. It allows signals to pass through. The jJ counter 30 converts these clock signals.

By doing this, the counter 30 makes the pulse width of clock pulse C run i and t3 half the pulse width of tl and pulse width of t2 in FIG. It will be similar to . Therefore, the counter 30 counts the output pulse width of the RS flip 70 knob 7 and the output pulse width of the RS flip-flop 8 using half the clock pulses, and the fourth
This means that we have obtained t4+t5 in the figure.

By importing the contents of this counter into the microcontroller 50 and dividing the value by 2, the output signal width of the RS flip-flop 7 and the output signal width of the RS flip-flop 8 are averaged. I can do it. This time is referred to as T2.

D flip-flop 10 is a frequency dividing circuit.

The counter 40 counts the time it takes for the rotating body 1 to rotate once, and measures the time from when the slit SR1 passes the reference point R1 until when the same slit 1 to SRI passes the M single point R1 next time. This time is T1.Then, the above-mentioned 360°X (T2/
By calculating T1>, the angle measurement value can be obtained.

Generally, a multi-digit counter requires a large mounting space and consumes relatively large amount of power. However, with the above arrangement, since the J counter 30 is the only counter with a multi-digit measurement angle, the overall shape of the angle measuring device can be made compact and can be said to be energy efficient.

Figure 5 shows the principle of compensating for measurement errors when measuring angles as described above. For example, if the slit interval is 90', an included angle of 90° is set at each position of the theodolite. This is the error curve measured by . Here, the solid line curve (Section, error curve by conventional method (4th section)
In the figure, the output signal of the RS flip-flop 7 and the D
This is the error curve when only the output signal of the flip-flop 10 is used. In addition, in the figure, the dashed line j
J-Bu is the second Surin 1-S R2J Yuyo and 8M
2 (in FIG. 4, an error curve when only the output signal of the RS flip-flop 8 and the J signal output from the D flip-flop 10 are used).

By the way, in the embodiments shown in Figs. 1 to 4, measurements are made by adding the error curve shown by the solid line and that shown by the broken line in Fig. 5, and the phases of these two curves are shifted by 90 degrees. . For this purpose, the error when setting slits at 90° intervals is l! l! In reality, it can be reduced to zero. In order to make the error zero in this way, both pulses p1 and p2, which are the M1 output signals, must be
It is necessary that the pulses D1 and D2 exist during the interval t6 shown in the figure.
．． This occurs when 8M2 passes the measurement point M1, and the interval t6 is the longer interval among the pulse intervals of the R1 output signal).

However, depending on the direction of the reference arm 4, this distance t6
It is possible that there is no pulse p1 or p2 in between. The invention provides that during this interval t6 the pulses p1. Therefore, there are two angle measurement points M1. The feature is that one of M2 is selectively used.

FIG. 6 shows that during interval t6, the pulse p1 or p2
This is the time tisade in the case that does not exist. This example:
This is a case where the phase of the R1 output signal is slightly delayed from the phase of the M1 output signal, and when compared with the case in FIG. 4, R1,
This shows a case where the phase relationship of each output signal of Ml is reversed. At this time, the contents of the counter 30 and the counter 40
If the contents of . . .

Therefore, in order to always perform the same operation as explained with reference to FIG.
First, it is determined in which direction the reference arm 4 shown in the figure is oriented. Then, during t6, the pulse p1. which is the M1 output signal. In order to make the angle measurement points M1.p2 exist, it is determined whether it is more appropriate to use the angle measurement points M1 or M2. M
2 may be selected.

For example, if the angle measurement point M1 is used to obtain the time chart 1 shown in FIG. Pulses pi and p2 are applied to.

In this way, the present invention has two slots 1- provided at intervals of angle r11 of 90° or less, two reference points R1, HV and two angle measurement points M1. The angle is measured using the pulse generated by passing through and covering the two Ml,
By appropriately selecting and using one of M2, it is possible to perform highly viscous angle measurement that compensates for rotational unevenness of two periods in one rotation of the rotating body 1.

Specifically, the means for selecting the angle measurement points Ml and M2 is, for example, a means for detecting the longer pulse interval t6 of the pulse intervals of the R1 signal, and detects the pulse l within this interval t6.
1. means for detecting whether pulses p1 and p2 are present together, and if pulses p1 and p2 are not present in the interval 1-6, output signal M1 to the angle measuring point M2; and means for using the signal. That is, one of the angle measurement points is selected depending on the relative position between the angle measurement point and the reference point.

By the way, instead of selecting the angle measurement point as above,
Since the same result can be obtained by selecting a reference point, the selection means may be any one that selects one angle measurement point and one reference point to be used in the angle measurement calculation.

Although it is important to set the timing to generate the measurement start signal shown in Figure 3.4, since the R1 output J signal is generated at irregular intervals, it is important to take advantage of this property. Therefore, the above timing can be appropriately obtained by using conventional techniques in a pre-measurement stage of the angle. This may be accomplished by using a separate circuit or by using the micro combi coater 50 to obtain the above timing.

As mentioned above, when compared with conventional angle measuring devices, the present invention mechanically measures one angle per rotation of the rotating body by simply adding one detected part to the rotating body. Since it is possible to sufficiently correct rotational irregularities in two cycles, it is possible to perform highly accurate angle measurements. In both cases, by selecting the angle measurement point, a counter with a multi-digit measurement angle can be combined into one, so that the device can be made compact and energy-saving.

[Brief explanation of drawings]

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 longitudinal 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 shows the principle of the present invention. Figure shown, No. 6
The figure shows another time chart that applies to the above embodiment. DESCRIPTION OF SYMBOLS 1... Rotating body, 1a, 1b... Disk, 2... Board, 3... Motor, 4... Reference arm, 5, 6.10
...D flip-flop, 7,8,9...RS flip 70 tube, 11...clock generation circuit, 12...
- Frequency dividing circuit, 30.40...Counter, 50...Microcomputer, R1, R2...Reference point as detection point, Ml. M2... Angle measurement point as a detection point, SRI, SR2
, 8M1.8M2...Slit as a detected part. Patent applicant: Asahi Optical Industry Co., Ltd. Agent: Kunio Miura

Claims (1)

[Claims] (1> Time required for the detected part provided locally on the constant velocity rotating body to make one rotation with respect to a fixed reference point llT1
and the time T2 required for rotating between the reference point and the angle measurement point, and calculates the angle to be measured by calculating 360° x (T2/TI). The detection unit is formed by two slits arranged at an angular interval of 90° or less, and two reference points and two angle measurement points are provided, and the relative position between the angle measurement point and the reference point is determined. An angle measuring device characterized in that it is provided with means for selecting each one angle measurement point and one reference point to be used for the angle measurement calculation according to the angle measurement calculation. 360°
The calculation of An angle measuring device characterized in that it is executed by one counter that counts clock pulses corresponding to the width of the pulse according to the angle measurement value, and another counter that counts one circumferential angle of the rotating body. . (3) The angle measuring device according to claim 2, characterized in that a 1/2 frequency divider is used in place of the other clock generation circuit.