JPH04335102A - Measuring instrument for displacement of rotary angle - Google Patents

Abstract

PURPOSE:To obtain a measuring instrument wherein the measuring range does not depend on the circuit characteristics and the circuits are simplified by generating a rotating pulse every time a shaft is rotated by a minute specified angle, obtaining the pulse period based on the passing time of the pulse, and obtaining the displacement of the rotary angle based on the fluctuation of the period. CONSTITUTION:A pulse generating part 11 comprises a gear which is fixed to a rotary shaft and a sensor. Every time the rotary shaft is rotated by a tooth pitch 9, a rotary pulse is generated. A period operating part 13 obtains the passing time of one pulse of the sensor S of the pulse generating part 11. A weighted average part 14 performs the weighted averaging of the passing times of the one pulse and obtains the average value of the periods. A dividing part 15 perform the dividing operation based on the passing time of one pulse from the period operating part 13 and the average value of the frequencies from the weighted average part 14 and obtains the displacement of the rotary angle. The output of the dividing part 15 is outputted through a digital output terminal in the intact state. The output is converted into the analog signal with a D/A converter 16. The analog signal is outputted through an analog output terminal.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to rotational fluctuations of a rotating shaft, etc.
This invention relates to a rotational angular displacement measuring device that measures rotational angular displacement (angular displacement).

0002

2. Description of the Related Art FIG. 5 is a block diagram showing an example of a conventional rotational angular displacement measuring device. This rotation angle displacement measuring instrument is
It is composed of a pulse generator 41, an amplifier 42, a PLL (phase locked loop) circuit 43, and a phase difference measuring device 44 (Japanese Patent Publication No. 1-27067).

The pulse generator 41 consists of a gear fixed to a rotating shaft, which is an object to be measured, and a sensor S, such as an electromagnetic pickup, placed opposite the gear. A rotation pulse is generated. The output of the pulse generator 41 is amplified by an amplifier 42 and then connected to a PLL circuit 43.

The PLL circuit 43 includes a phase detecting section 431 whose one input terminal is connected to the output terminal of the pulse generator 41;
The output end and the input end of the phase detection section 431 are detected by a low-pass filter 432 having a relatively large time constant, and the output end and the input end of the low-pass filter 432 are connected, and the output end is connected to the other end of the phase detection section 431. It consists of a voltage controlled oscillator 433 connected to the input terminal.

The phase difference measuring device 44 is for calculating the phase difference between two inputs as a digital value for each cycle of the inputs (see Japanese Patent Publication No. 57-6052). 41 and the output terminals of the voltage controlled oscillator 433, respectively.

[0006] The frequency of the rotational pulses output from the pulse generator 41 is a steady frequency proportional to the steady rotational speed of the rotating shaft when torsional vibration is not occurring on the rotating shaft. When torsional vibration occurs on a rotating shaft, a fluctuation component whose frequency periodically increases or decreases in positive or negative directions according to the torsional vibration period is superimposed on a steady frequency, that is, the center frequency. becomes.

[0007] This rotation pulse is introduced into a phase detection section 431 of the PLL circuit 43, and a phase shift with respect to the output of the voltage controlled oscillator 433 is detected. Subsequently, this detection output is
It is smoothed by a low-pass filter 432. As a result, the output of the low-pass filter 432 becomes a steady one, that is, a voltage corresponding to the center frequency, regardless of the presence or absence of torsional vibration, and the voltage controlled oscillator 13 outputs a reference pulse with a frequency corresponding to the voltage. is sent. Subsequently, the phase difference measuring device 44 calculates the phase difference between the reference pulse and the rotating pulse from the pulse generator 41 for each cycle.

[0008] Therefore, the frequency of the reference pulse corresponds to the center rotation speed of the rotating shaft, and the frequency of the rotation pulse corresponds to the superposition of the fluctuating rotational component accompanying torsional vibration via the center rotation speed. . In other words, the phase difference between the two frequencies is
This corresponds to the angular displacement caused by torsional vibration at the rotation pulse extraction point of the rotating shaft.

[0009]

[Problems to be Solved by the Invention] However, the above-mentioned conventional rotational angular displacement measuring device has a sensor output signal processing system (PL).
Since the L circuit) is an analog circuit and includes a low-pass filter, the characteristics of the signal processing system are determined by its time constant. In addition, if the measurement range is large, PLL
There was a possibility that the circuit would become unlocked, making measurements impossible.

On the other hand, the above-mentioned pulse generator uses gears, encoders, etc., and performs periodic calculations based on the pitch thereof. This pulse generator requires modification if it is to be incorporated into an existing rotating machine. Furthermore, since the pitch of gears etc. affects the measurement results, high accuracy is required.

An object of the present invention is to provide a rotation angle displacement measuring instrument whose measurement range does not depend on circuit characteristics and whose circuit can be simplified by digitizing the signal processing system.

Another object of the present invention is to provide a rotational angular displacement measuring instrument in which the pulse generating means can be easily attached to rotating equipment and does not require high mounting accuracy.

[0013]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the rotational angular displacement measuring device according to the present invention includes a pulse generating means that is provided on a rotating shaft and generates a rotational pulse every time the shaft rotates by a small fixed angle. A period calculating means for calculating a pulse period from the pulse transit time generated by the pulse generating means, and an angular displacement calculating means for calculating a rotational angular displacement from a fluctuation in the pulse period calculated by the period calculating means.

In this case, the pulse generating means may include a striped reflective tape attached to the rotating shaft.

[0015] Further, the pulse generating means may include two pulse generators arranged at a predetermined angle with respect to the rotational direction of the rotary shaft.
The detector may be characterized in that it includes two detectors.

Further, the angular displacement calculation means includes a weighted averaging section that calculates an average value of the periods by weighted averaging the pulse periods determined by the period calculation means, and a weighted averaging section that calculates the average value of the periods by weighted averaging of the pulse periods determined by the period calculation means; and a division section that calculates the rotational angular displacement by dividing by the average value of the period calculated by the averaging section.

[0017]

According to the present invention, the pulse period is determined by the period calculating means from the pulse passing time generated by the pulse generating means, and the rotation angle displacement is determined from the variation of the pulse period.

[0018]

EXAMPLES The present invention will be described in detail below with reference to the drawings and the like. FIG. 1 is a block diagram showing a first embodiment of a rotational angular displacement measuring instrument according to the present invention, and FIG.
FIG. 3 is a diagram illustrating the operation of a weighted average unit included in the first embodiment. The rotation angle displacement measuring device of this embodiment mainly includes a pulse generator 11, an amplifier 12, a period calculation section 13, a weighted average section 14, a division section 15, and the like.

The pulse generator 11 consists of a gear fixed to a rotating shaft, which is an object to be measured, and a sensor S, such as an electromagnetic pickup, placed opposite the gear. A rotation pulse is generated. The output of the pulse generator 11 is amplified by an amplifier 12 and then connected to a period calculation section 13.

The period calculating section 13 calculates the transit time (T+ΔT) of one pulse of the sensor S of the pulse generator 11. Here, T is the average value of the pulse period, and ΔT is a fluctuation component of the pulse period. The output terminal of the period calculation section 13 is connected to the input terminal of the weighted average section 14 and one input terminal of the division section 15.

The weighted average unit 14 calculates the passing time of one pulse (
T + ΔT), the average value of the period T
The output terminal of the weighted average section 14 is connected to the other input terminal of the division section 15.

In other words, as shown in FIG.
, the value obtained by calculating 1/N of the value Nyn-1 by the divider 143 is subtracted by the subtracter 144, and the value is subtracted by the adder 141.
Then, the average value of the frequency T is obtained by repeating the operation of adding new data Tn to it. That is,
T1 → y1 = T1 T2 → y2 = (T1 + T2 )/2
[∵ 2y2 = T2 + (1-1/2
)・2・T1 ] T3 →y3 =T1 +T2
+T3 [∵ 3y3 =T3
+(1-1/3)・3・(T2 +T1)/2]
: Tn → yn = ΣTn /N = (average value of T)

[
The division section 15 is a section that divides the one-pulse transit time from the period calculation section 13 and the average frequency value from the weighted average section 14 to obtain a rotational angular displacement. That is, in the division unit 15, (T+ΔT)/T=1+ΔT/T
Perform the calculation. Here, 1/T corresponds to the average peripheral speed v, so ΔT×1/T corresponds to the displacement, that is, the twist angle.

The output of the divider 15 is output as is from the digital output terminal, and is also converted into an analog signal by the D/A converter 16 and output from the analog output terminal.

FIG. 3 is a block diagram showing a second embodiment of the rotational angular displacement measuring instrument according to the present invention, and FIG. 4 is a diagram illustrating the operation of the second embodiment. The rotation angle displacement measuring device of this embodiment is composed of a pulse generator 21, amplifiers 22A and 22B, a period calculation section 23, and the like.

The pulse generator 21 includes a striped reflective tape 30 attached to a rotating shaft, and two photoelectric reflectors placed opposite the striped reflective tape 30 and spaced apart by an angle θ on a plane perpendicular to the rotating shaft. It is composed of type sensors S1 and S2. The interval between the sensors S1 and S2 is set smaller than the pitch of the striped reflective tape 30. Note that if the sensor interval is set to be larger than the stripe pitch for reasons such as implementation, the stripe pitch signal may be frequency-divided. Sensor S1, S2
The outputs are amplified by amplifiers 22A and 22B and then connected to two input terminals of the period calculation section 23.

As shown in FIG. 3, the period calculation unit 25 is a part that calculates the period T by counting the time difference between the stripe pitches passing through the sensors S1 and S2 using a reference clock. When the bright part of one stripe of the striped reflective tape 30 passes through the sensor S1 [FIG. 4(a1)], the sensor S1 becomes high level [FIG. 4(b)], and the period adding section 23 starts adding [
Figure 4(d)]. When the bright part of the stripe passes through sensor S2 [Figure 4 (a2)], sensor S2 becomes high level [
FIG. 4(c)], the period adder 23 completes the addition [FIG.
d)], the period T can be determined. The following configuration and operation are similar to those of the first embodiment.

[0028]

As explained in detail above, according to the present invention, the signal processing system can be digitized, so the measurement range depends only on the frequency characteristics of the sensor and is not affected by the circuit characteristics. can be achieved.

Furthermore, if a striped reflective tape is used as the pulse generating means, it can be easily incorporated into existing rotating machinery.

Furthermore, if the two detectors are placed apart by a predetermined angle, the measurement standard is not based on the stripe pitch but on the mounting angle of the two detectors, so the accuracy will be affected by how the striped reflective tape is applied. Not done.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of a rotational angular displacement measuring device according to the present invention.

FIG. 2 is a diagram illustrating the operation of a weighted average unit included in the first embodiment.

FIG. 3 is a block diagram showing a second embodiment of the rotational angular displacement measuring device according to the present invention.

FIG. 4 is a diagram illustrating the operation of the second embodiment.

FIG. 5 is a block diagram showing an example of a conventional rotational angular displacement measuring device.

[Explanation of symbols]

11 Pulse generator 12 Amplifier 13 Periodic calculation section 14 Weighted average part 15 Division part 21 Pulse generator S1, S2 sensor 22A, 22B Amplifier 23 Periodic calculation section 30 Striped reflective tape

Claims (4)

[Claims] 1. A pulse generating means provided on a rotating shaft and generating a rotational pulse each time the shaft rotates by a small fixed angle; and a period calculating means for calculating a pulse period from a pulse passing time generated by the pulse generating means. and angular displacement calculating means for determining rotational angular displacement from fluctuations in the pulse period determined by the period calculating means. 2. The rotational angular displacement measuring device according to claim 1, wherein the pulse generating means includes a striped reflective tape attached to the rotating shaft. 3. The pulse generating means includes two detectors arranged at a predetermined angle with respect to the rotation direction of the rotation shaft. Rotational angle displacement measuring instrument. 4. The angular displacement calculation means includes a weighted averaging section that calculates a period average value by weighted averaging the pulse periods determined by the period calculation means; 4. The rotational angular displacement measuring instrument according to claim 1, further comprising a dividing section that calculates the rotational angular displacement by dividing by the average value of the period calculated by the averaging section.