JPS62123360A - Position and speed detector - Google Patents

Abstract

PURPOSE:To provide high-accuracy detection of position and speed with strong resistance to such external disturbances as noise, etc., by performing arithmetic operation of a displacement distance per unit of time, detecting position and speed with digital values and converting them from digital to analog ones. CONSTITUTION:An encoder generates 2-phase sinsoidal wave signals A, B featuring mutually pi/2 phase differences corresponding to displacement or revolution of a body. A comparing circuit 11 binarizes these signals with zero volts and converts them into rectangular wave signals S, T and an arithmetic operating pulse generator 12 generates addition and subtraction signal PSW and polarity reversing signal PNW with signals S, T. Further, an A/D convertor 14 performs A/D conversion of the signals A, B held in a sample hold circuit 13. And, a displacement arithmetic operation circuit 15 performs on arithmetic operation of displacements per unit of time and these accumulated value with a digital value and issues out the operated position and speed signals after respective D/A conversions 16, 17. Thus, pulses are interpolated from the signals A, B only by digital processes for obtaining the position and speed signals.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a position and speed detection device based on the movement or rotation of an object, and particularly to a position and speed detection device that constitutes a control system of a servomechanism using a drive device such as a motor. This invention relates to a detection device.

[Conventional technology]

Conventionally, as a method for detecting position when configuring a positioning servo system, a rotary encoder or a linear encoder or the like has been used to obtain a position signal by counting position pulses. Further, as a method for detecting the speed, the speed signal is obtained by performing the above-mentioned position pulse number iF/V conversion.

FIG. 4 is a block diagram showing an example of a conventional circuit of a device for detecting position and velocity using sine waves A and B with a phase difference of π/2, and FIG. 5 is a waveform diagram of each part thereof.

In Fig. 4, (1) is a motor, (2) is an encoder driven by this motor (1), (3) is a sine wave A with a phase difference of π/2 output from the encoder (2),
B is an input pulse oscillator, (4) is an up/down counter, (5) is a pulse adder, (6) is a direction discriminator,
(7) converts the position signal into an analog value and outputs it +D/
A converter (8) is an F/V converter that performs F/V conversion of the direction discrimination signal FRW, and (9) is an operational amplifier that outputs a speed signal.

Next, the operation will be explained. If the A phase is ahead of the B phase, the pulse generator (3, IPAG generates a positive direction pulse CW, and the up/down counter (4)
CN T, pulse adder (5) ORC and direction discriminator (6) FRCK input. The up/down counter (4) CNT is counted up by one each time a positive direction pulse CW is input, and the count value is DA.
Converter (7) The signal is input to the DAC and converted into DA. Therefore, the position signal P increases stepwise as shown in FIG.

Direction discriminator (6) FRC receives the positive direction pulse CW and outputs a direction discrimination signal FRW indicating the positive direction as shown in FIG. Pulse adder (6) ORC adds the positive direction pulse CW and the negative direction pulse CCW, and generates the position pulse P.
Input RW to FV converter (8) FVC.

The FV-converted signal FV is input to an operational amplifier (9) INCK, and non-invertingly amplified by the direction discrimination signal FRW.

Therefore, the speed signal V is outputted in a stepwise manner with positive polarity as shown in FIG.

On the other hand, if the A phase is delayed in phase from the B phase, the pulse generator (3) PAG generates a negative direction pulse CCW, and the count value of the up/down counter (4) CNT is down. , a direction discriminator (6) FRC, and a pulse adder (510RC), which output a direction discrimination signal FRW indicating a negative direction and a position pulse PRW.

The signal FV obtained by FV conversion of the position pulse PRW has the same polarity as in the previous case, but is inverted and amplified by the operational amplifier (9) INC from the direction discrimination signal FRWK. Therefore, the position signal P decreases in a stepwise manner, and the speed signal V also decreases in a stepwise manner with negative polarity.

[Problem that the invention seeks to solve]

Since the conventional position and speed detection equipment is configured as described above, both the position signal P1 and the speed signal ■ have a step-like shape, which not only makes it impossible to obtain smooth position and speed signals, but also makes it difficult to obtain smooth position and speed signals. There were problems in that accurate position and speed signals could not be detected because fluctuations could not be detected.

This invention was made to solve the above-mentioned problems. It enables smooth position and speed detection, is resistant to disturbance factors such as noise, enables high-precision detection, and is easy to apply to servo systems. The object of the present invention is to obtain a position and speed detection device that can be configured as follows.

[Means for solving problems]

The position and speed detection device according to the present invention uses sine wave signals A and B having a phase difference of π/2 according to the movement or rotation of an object.
It is equipped with means for generating and counting position pulses, and means for interpolating the position pulses by digital processing from the AD conversion values of the sine wave signals A and B, and calculating the amount of movement per unit time to calculate the position and velocity. In addition to detecting digital values, they are DA-converted to obtain position and velocity signals.

[Effect]

The position and speed detection in this invention detects movement per unit time not only by position pulses but also by a two-phase sine wave signal A.
, B can be detected with high accuracy by combining the AD-converted values with those obtained by calculation of minute fluctuations less than the position pulse. 2. The phase sine wave signals A and B are added to or subtracted from each other by their AD conversion values, and by selecting one of them as appropriate, an interpolated signal MS indicating a displacement with respect to the position pulse PRW is obtained. On the other hand, the value of the up/down counter CNT is a signal indicating the position by the number of position pulses.

The above-mentioned interpolation signal MS and counter value are taken in every sample time △T, and subtracted from the previous value to calculate the inter-pulse movement amount and pulse movement amount for each △T, and by combining them, the inter-pulse movement is interpolated. The speed is shown as a digital value. Furthermore, by accumulating these values, the interpolated position between pulses is shown as a digital value.

[Embodiments of the invention]

FIG. 1 is a block diagram showing a circuit configuration of a position and speed detecting device according to an embodiment of the present invention, and shows (1) to (1) to (1) to (1).
4) are the same or corresponding parts as the same reference numerals in FIG. 4 showing the conventional example. αη is the rectangular wave signal S, T obtained by binarizing the sine wave signals A and B from the encoder (2) at zero volts.
(6) is an arithmetic pulse generator that generates an addition/subtraction signal PSW and a polarity inversion signal PNW based on the rectangular wave signals S and T; αJ is a sine wave A per unit time;
A sample and hold circuit to hold B, and a4 is an A/D that converts the held sine waves A and B into A/D.
Converter, (to) is a movement calculation circuit that calculates the movement amount per unit time and its accumulation in digital values, αQ and α
η is the calculated position signal and speed signal respectively.
The D/A converter 08 is a timer circuit that manages unit time.

Figure 2 is a waveform diagram of each part in Figure 1, Figure 3 (a) is the processing timing when the sine wave signal A is ahead of B by π/2, and (b) is the processing timing when the sine wave signal A is also ahead of B by π/2. Show the diagram.

Next, the operation of this invention will be explained. In the rectangular wave signals S and T indicating the positive and negative of the two-phase sine wave signals A and B, when positive is 111 and negative is 101, S = 111,
When 'l' = 101, addition and non-inversion 5 = 11 blind
When 'l'=lit, subtraction and inversion 5=101,
When T=111, addition and inversion 5=10! , T=1
When the signal is 01, an addition/subtraction signal DSW indicating subtraction and non-inversion and a polarity inversion signal PNW are generated.

At a certain time to, the count value of the N-bit up/down counter (4) CN T, the addition/subtraction signal PSW,
The values of the polarity inversion signal PNW and the sine wave signals A and B are sampled and held by the SHC,
Obtain PSo, HA, HB. This bold value 1-1A
, l(B is AD converted by an N-bit AD converter α3ADC to obtain SAo and SBo.

As shown in FIG. 6, the movement amount calculation circuit α5MPC outputs the latched addition/subtraction signal PSW and the polarity inversion signal P N W
Accordingly, SAo +SBo, SAo +SBo.

One of SA, -SBo, and SAo-SBo is calculated and its value is set as MSo. However, SA6, SBo,
P.S.

represents a negative number in two's complement, SAG + SBO.

SAo-3B0 is SAo + S Bo, SA
o S Bo is inverted.

Next, if we perform the same process at time tl after ΔT seconds and obtain count value PSl and interpolated value MSl, then P
si PSO indicates the amount of pulse movement in △T seconds, and MS
, -MS, indicates the inter-pulse movement amount.

This gives DV = (PSl-PS-o)X2N+(MSt
By calculating Mo), the amount of movement per 1 second, that is, the speed, is shown by the digital value of the M-1-N pit.
.

On the other hand, the position can be determined by adding the velocity DV every ΔT seconds, DP=ΣDVi L=.

By calculating this, it is expressed as an M+N bit digital value.

In this way, position and velocity are detected with a resolution of 1/2N between position pulses and as digital values, so position and velocity can be easily detected.
A highly accurate servo system with speed feedback can be configured digitally. Further, when position and velocity are expressed as analog values, it is sufficient to perform DA conversion of the position fiDP and velocity DV every ΔT seconds, and an analog servo system can also be constructed.

The above arithmetic processing can be easily configured using logic circuits such as digital adders and latches, and the sampling time ΔT can be shortened, so that smooth position and velocity signals can be obtained. Note that the maximum amplitude of the two-phase sine wave signals A and B is constant with respect to the frequency, and the pulse-to-pulse movement i11s1
- In order to make the maximum value of MSo correspond to one pulse,
The maximum amplitude value needs to be twice the input voltage of the AD converter.

In the above embodiment, a case has been described in which the arithmetic processing is performed only by hardware using a digital adder, etc. However, if an arithmetic device such as a microcomputer is used, there is no need to generate the addition/subtraction signal DSW and the polarity inversion signal PNW. , the same effect as above is achieved. In addition, although we have shown the case where the position pulse is generated when the two-phase sine wave signals A and B cross zero volts, we also generate the sum signal (A + B) and difference signal (A - B) of each. It can also easily be used to similarly generate position pulses, and the resolution can be further improved.

As described above, the present invention is not limited to the embodiments, and various modifications are possible.

〔Effect of the invention〕

As described above, according to the present invention, the two-phase sine wave signal A,
Not only can smooth position and velocity signals be obtained by interpolating position pulses only with B, but the arithmetic processing section is constructed with a digital circuit, so it is resistant to disturbance factors such as noise, allows for highly accurate detection, and is easy and inexpensive. It has the advantage of being able to configure a servo system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the circuit configuration of a position and speed detection device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of each part thereof, FIG. 3 is a processing timing diagram thereof, and FIG. 4 is a conventional position and speed detection device. Block diagram showing the circuit configuration of the speed detection device, No. 5
The figure is a waveform diagram of each part. In the figure, (1) is the motor, (2) is the encoder, (
3) is a pulse generator, αV is a comparison circuit, α→ is an A/D converter, (g) is a movement amount calculation circuit, αq, O'it&
Yori/A converter. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Patent Attorney Masaru Sato Year II 2 Figure CW

Claims (3)

[Claims] (1) An encoder that generates two-phase sine wave signals A and B with a phase difference of π/2 according to the movement or rotation of an object, and generates a pulse every time the sine wave signals A and B cross zero volts. a comparator circuit that adds and subtracts the pulses; an A/D converter that converts the sine wave signals A and B from analog to digital; a movement amount calculation circuit that digitally calculates the position and speed signals; A position and speed detection device characterized in that it is provided with a D/A converter for digital-to-analog conversion of digital calculation results, and interpolates pulses from the sine wave signals A and B using only digital processing to obtain position and speed signals. (2) SA the digital conversion value of the two-phase sine wave signals A and B.
, SB, and the signals indicating positive and negative are S and T. If S='1' and T='0', then SA+SB, and S='
1', if T='1', use @SA-SB@, S='0
', if T='1', use @SA+SB@, S='0'
, if T='0', select and calculate SA-SB, and subtract it from the calculated value ΔT seconds before to detect the inter-pulse movement amount for ΔT seconds, and calculate the amount obtained from the difference in pulse count values. The speed detection according to claim 1, characterized in that the speed interpolated between the pulses is expressed as a digital value by combining with the pulse movement amount, and the speed signal is converted into a speed signal through digital-to-analog conversion. Device. (3) By accumulating the speed signals obtained through the processing described in the preceding paragraph, the position interpolated between pulses is indicated as a digital value, and the position signal is converted into a position signal through digital-to-analog conversion. A position detection device according to claim 1.