JPS5852566A - Frequency modulation system angular velocity and angular displacement detector - Google Patents

Abstract

PURPOSE:To obtain a detector whose inertia is small, by using a slit disk connected to a shaft to be measured, opposingly providing a light source and a photodetector so as to move a turning-on or light receiving point in the rotating direction of the disk by a referece pulse, and executing the demodulation and operation. CONSTITUTION:An angular velocity and angular displacement detector is constituted of a detecting part 10, a light source driving part 20, a demodulating part 30 and an angular displacement operating part 40. In the detecting part 10, a slit disk 11 which has cut-provided a lot of slits 12 in the radial direction is supported so as to be rotatable, and to a rotary shaft 13 of the disk 11, a shaft to be measured is connected. On the disk 11, a light source group 14 and a photodetector 15 are opposingly provided by placing a slit part between them. A light source of the light source group 14 is connected to each bit of a ring counter 21 of the driving part 20, and is turned on in order to as to move in the rotating direction of the disk 11. A pulse signal to be modulated, which is obtained by the element 15 is obtained as an angular velocity output by the demo-dulating part 30, and is operated in accordance with a reference pulse obtained by a frequency dividing circuit 43 in the operating part 40, by which an angular displacement output can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency modulated angular velocity/angular displacement detector.

Conventionally, when performing position control using a servo motor, the first
The configuration shown in the figure is common. That is, a potentiometer 3 is provided on the output side of a gear head 2 driven by a servo motor 1, and the displacement detected by the potentiometer 3 is compared with a position setting value, and the servo is adjusted via a power amplifier 4 so that the difference between them becomes zero. A minor speed loop was constructed using a tacho generator 5 that drives the motor 1 and also detects the speed of the servo motor 1.

However, the installation of a potentiometer for position detection and the mechanical full scale must be considered each time depending on the object, so recently, in addition to the up/down counter 8 to which the second position setting pulse is sent, the and its output is sent to the power amplifier 4 through an A/A converter 9.

The present invention aims to provide an angular velocity/angular displacement detector having a low inertia equivalent to that of the rotary encoder described above, and more specifically, by providing the rotary encoder with the function of a tacho generator, the inertia The present invention aims to provide an angular velocity/angular displacement detector in which the tachogenerator, which has a large tachometer, is omitted and the precise detection speed range can be easily changed by the clock frequency of the electronic circuit.

A shaft to be measured is connected to the rotary shaft 13 of the disc 110.

On the slit disk 11, a light source group 14 and a light receiving element 5 are arranged opposite to each other with the slit portion sandwiched therebetween.
When the number of slits per round in the light source group 14 is N [P/rev], and therefore the slit pitch angle is f△ [raIi], as shown in FIG. light emitting diode) 162π 1 is N(M 1K ) (raIil (however, K is 0
．． ±1. They are arranged at intervals of ±2, ...).

Each of the light sources [6] is connected to each bit of an n-bit ring counter 21 in the light source driving section 20, and moves repeatedly over a range of 2π N(1+K) [ratl]. Here (-,,,) is twice the pitch of the slit, and the phase relationship between the slit and the light source can be considered by shifting the pitch, so the range of the center (one pitch) of the light source can be repeatedly moved. If you look at it, you can think of it as rotating continuously.

Therefore, when the slit is stationary, the amount of light that reaches the light receiving element 15 changes at a frequency of:

One==.

Then, the output frequency f is f　”　fo　　”f.

becomes. Also, if it rotates in the opposite direction, f-71"""-B-f. = fo, 10 kf.

becomes. This is frequency modulated by the rotational angular velocity ω of the slit, and by demodulating this signal, a DC signal proportional to the rotational angular velocity can be obtained.

In the preamplifier 31 in the demodulator 30 of FIG. 3, two pairs of emitters and receivers are provided with a phase shift of 90 degrees with respect to the Panlit pinch, and the rotation direction is detected from the phase relationship of these outputs, and the up/down counter is increased/decreased. There is. The angular displacement calculating section 4o in FIG. 3 realizes a function corresponding to this using the modulated pulse signal from the light receiving element 15.

That is, the modulated pulse signal outputted from the band pulse filter 32 is waveform-shaped in a waveform shaping circuit 41 consisting of a comparator, etc., and then sent to the amplifier down counter 42, where the counter is incremented at the rising edge. Further, it is possible to obtain an angular displacement output signal in which the clock pulse (fc) from the clock generator 22 changes by 1 per minute displacement, and an analog output can be obtained by the A converter 45. Similar to a general incremental encoder, in order to update the value every 1/2 pitch, the reference pulse and the modulated pulse are differentiated, and both of their rising and falling edges are used. At the same time, Δτ All you have to do is delay lunch by (-,).

In addition, the output of the amplifier down counter 42 is connected to the converter 4.
6 directly performs /A conversion, and outputs the output from a low-pass filter 47 (multiply by 2). It is more advantageous to use a commercially available mass-produced product in which light-receiving elements are arranged at regular intervals.

FIGS. 6 and 7 show an embodiment in which such an element can be used. In the detection section 50 of this embodiment, a slit disk in which a large number of slits IJ)) 52 are cut in the radial direction is used. A fixed slit plate 57 having a slit 58 slightly curved and inclined with respect to the slit 52 is superimposed on the slit 51, and a light source group 54 and a light receiving element 55 are inserted between these slits.
It is set up oppositely. The relationship between the slits 58 in the fixed slit plate 57 and the pinch of the slit disc A can be easily adjusted.

It should be noted that the other configurations are the same as those of the previous embodiment, so the explanation thereof will be omitted.

In both of the above embodiments, a case has been described in which the lighting portions of the light source groups 14 and 54 are moved, but similar effects can be expected even if the light receiving points of the light receiving elements 15 and 55 are moved. In this case, the slit disk]]
, 5], which projects uniform light onto a light-receiving element that does not have an accumulation effect, such as a solar cell or photodiode, or a CCD.
It is possible to use a light-receiving element having an accumulation effect such as the following. However, by detecting both the angular velocity and the angular displacement (1) by detecting both the angular velocity and the angular displacement, it is possible to measure the rotational displacement like the known incremental encoder Even without providing separate light emitters and receivers, it is possible to easily detect the direction as well.

(2) Since the load on the system to be measured is only the disk, the inertia is small and does not affect the system to be measured.

(3) The speed detection range is determined by the moving speed of the light source, which is determined by the clock f of the ring counter. can be easily changed. Therefore, it is extremely easy to change the detection range.
The range of applications becomes wider.

(4) In general, when detecting a low speed range, the low speed tachogenerake has a large number of poles, so it has a large inertia and has the disadvantage of being expensive. However, according to the detector of the present invention, it can be used in the low speed range as well as in the high speed range.

(5) Since the frequency characteristic of the output is determined by f0, it can be selected from a wide range by selecting the number of slits and the speed of the light source.

[Brief explanation of drawings]

Figures 1 and 2 are block diagrams of a known device that performs position control using a servo motor, Figure 3 is a block diagram of an embodiment of the present invention, Figure 4 is a detailed diagram of its main parts, and Figure 5 ( a) to (e) are waveform diagrams of signals processed by the device of the present invention, FIG. 6 is a configuration diagram showing each part of the detection unit in another embodiment of the present invention in a separated state, and FIG. 1) is an explanatory diagram showing the arrangement state of 7). II, 5] ・ ・ ・ Surinote disk, 12 , 52 ... slit, 14 , 54 ... light source group, 15 , 55 ...
Light receiving element, 16... Light source, 30... Demodulator,
40...Angular displacement calculation section, 57---Fixed slit plate, 58---Sli
Note, 59...Fist moire stripes. designated agent

Claims (1)

[Claims] 1. A frequency characterized in that a large number of slits are cut in the radial direction on a slit disk connected to the shaft to be measured, and a slit portion □””il 1 calculation portion is provided. Modulation type % type % 2. A large number of slits are cut in the radial direction on a slit disk connected to the axis to be measured, and the moiré fringes move in the radial direction with respect to this slit disk as it rotates. A fixed slit plate with slits cut in it is installed overlappingly, and the light source and the light receiving element are connected by sandwiching these slits, so that the illuminated part of the light source and the light receiving point of the light receiving element are sequentially adjusted by the reference pulse to the radius of the slit disk. Install them oppositely so that they move in the direction,
A frequency modulation system characterized by comprising: a demodulation section that demodulates the output of the light receiving element to obtain an angular velocity output; and an angular displacement calculation section that obtains an angular displacement output based on the output of the light receiving element and the reference pulse. Angular velocity/angular displacement detector.