JPH0230726Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a phase modulation type position detection device equipped with an origin adjustment device.

When attaching a position detector to a mechanical system to be detected, it is important to match the origin of the mechanical system with the origin of the position detector. Conventionally, such origin alignment has been carried out exclusively by connecting the two parts so that their origin points mechanically coincide with each other during installation. Therefore, the two had to be connected to avoid errors, which posed a problem in that the installation work was time-consuming. In addition, the two are usually connected by screws, etc., but even if the mechanical origins of the two are accurately matched, the installation accuracy often deteriorates at the screw tightening stage. It was difficult to mechanically align the two origins completely. By the way, if the detection resolution of the position detector is not very high, even if the origin is slightly shifted, the detection accuracy will not be affected, so a certain degree of installation error is allowed, and it can be done relatively easily. I was able to install it. However, in the case of high-resolution position detectors such as phase modulation type position detectors, the tolerance range for mounting errors in the origin is extremely limited, so it is necessary to align the origin and mount it to avoid errors. It was an extremely difficult technique.

This idea was made in view of the above points,
It is an object of the present invention to enable easy alignment of the origin when installing a position detector, particularly a phase modulation type position detector, in a mechanical system. The phase modulation type position detector is
It generates an output that is a reference AC signal phase-modulated by a phase angle corresponding to the detection target position, and the position of the detection target can be determined by measuring the phase shift between the reference signal and the output signal. The above purpose is to insert a phase shift circuit that can appropriately shift the phase of the output signal of the phase modulation type position detector on the output side, and to compensate for the error caused by mechanical origin alignment by this phase shift circuit. This is accomplished by electrically modifying the circuit. In other words, if the origin of the mechanical system and the origin of the detector are not installed so that they perfectly match, when the current position of the mechanical system is at the origin, the phase modulation type position detector will experience a phase shift corresponding to the installation error. The resulting AC signal is output. Therefore, the origin can be adjusted by adjusting the amount of phase shift in the phase shift circuit so as to offset the phase shift due to this installation error.

An embodiment of this invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, a phase modulation type position detector 13
is the mechanical system 1 that is the detection target for the reference AC signal P.
The output signal E' is phase-modulated by a phase angle corresponding to the position No. 2, and the output signal E' is input to the detection circuit 16 via the phase shift circuit 14. The detection circuit 16 uses the reference AC signal P and the phase shift circuit 14.
Measuring the phase shift with the output signal E of the mechanical system 1
A signal D corresponding to position 2 is output. Display 1
In step 7, the output is displayed in an appropriate display format.
The reference AC signal P is generated in the oscillation circuit 18 and supplied to the position detector 13 and the detection circuit 16, respectively. The phase shift circuit 14 appropriately shifts the phase of the output signal E' of the position detector 13 in accordance with the operation of the operating section 15.

The position detector 13 is attached to the shaft of the mechanical system 12 to be detected via an appropriate means such as a screw.
If the two origins do not match completely and there is a mounting error, the output signal of the position detector 13
A phase shift occurs in E' depending on the installation error.
Now, assuming that the current position of the detection target 12 is at the origin and the amount of phase shift in the phase shift circuit 14 is 0, the phase of the output signal E' of the detector 13 is not shifted, and the detection circuit remains as it is. 16, a value corresponding to the installation error is displayed on the display 17. In this state, if the operation unit 15 is operated so that the value on the display 17 becomes 0, and a suitable amount of phase shift is performed in the phase shift circuit 14, a signal E that cancels out the phase shift corresponding to the installation error will be generated from the phase shift circuit. Obtained from 14. In this way, since the origin is electrically adjusted by the moving circuit 14, the detection circuit 16 can perform accurate phase shift detection (i.e., position detection) based on the position detection signal E for which the origin has been adjusted. can.

An example of the phase modulation type position detector 13 is shown in FIG. In Fig. 2, the stator (iron core) 1 consists of four excitation poles A, B, C, and D arranged at 90 degree intervals in the circumferential direction, and two excitation poles A and D facing each other in the radial direction. C forms one pair, and excitation poles B and D form another pair. Primary windings 2A and 2C or 2B and 2D are differentially wound around the excitation pole pair A and C or B and D. In other words, if the direction of the magnetic flux toward the end of each magnetic pole A, B, C, and D is in positive phase, the magnetic fluxes generated by each winding A and C or B and D are wound so that they are in opposite phase to each other. ing.

A rotor 3, which faces the ends of each of the excitation poles A to D with a suitable gap interposed therebetween, rotates together with the rotating shaft 4. A rotational position θ to be detected is given to this rotational shaft 4. The rotor 3 has a shape that changes the permeance of the magnetic path passing through each stator excitation pole A, B, C, and D in accordance with the rotational position θ. In the example shown in FIG. 2, the rotor 3 is connected to the rotating shaft 4.
It has a cylindrical shape and is mounted eccentrically with respect to the center. Due to this eccentric cylindrical shape, the gap distance between the cylindrical side surface of the rotor 3 and the end of each pole A, B, C, and D changes depending on the rotational position θ. This gap change causes a permeance change in each pole A, B, C, and D that corresponds to one period of trigonometric function per revolution of the rotor 3.

The excitation pole pair consisting of A and C and the excitation pole pair consisting of B and C are separately excited by alternating current signals that are 90 degrees out of phase. In the figure, primary windings 2A and 2C of poles A and C are connected in series, and a sine wave signal i _a =Isinωt is applied from an oscillator 5. Also, poles B and D
The primary windings 2B and 2D of are connected in series, and a cosine wave signal i _b =Icosωt is applied from an oscillator 6.

In the above configuration, each excitation pole A, B, C, D
2 to extract the voltages induced respectively by
The next winding 7 is wound around the stator 1. In the example shown in Fig. 2, secondary windings 7A and 7C are wound around excitation poles A and C, respectively, in phase, and secondary windings 7B and 7D are wound around excitation poles B and D, respectively, in phase. ,7A
and 7C, 7B, and 7D are in opposite phases to each other. These secondary windings 7A to 7D are connected in series so that a composite signal E of voltages induced at each excitation pole A, B, C, and D is extracted.

If cos θ is used to represent the permeance change in the magnetic pole pair A, C excited by the sine wave signal I cos ωt, then the permeance change in the magnetic pole pair B, D excited by the cosine wave signal I cos ωt is 90 Since it is shifted by degrees, it can be expressed using sinθ. Therefore, the composite signal E' of the outputs of the magnetic poles A to D can be expressed as follows.

E′=Ksin(ωt−θ)…(1) In other words, an AC signal E′ whose phase is shifted from the reference AC signal Isinωt by a phase angle corresponding to the rotational position θ of the rotor 3 is output from the detector 13. Ru.
Note that K is a constant.

An example of the oscillation circuit 18 and the detection circuit 16 is shown in FIG.

Oscillator 20 generates a high speed clock pulse CP. The frequency dividing circuit 21 divides the frequency of this clock pulse CP by 1/M and outputs a pulse P _b with a duty of 50% and an inverted signal P _a of this pulse P _b (where M is an arbitrary integer). Specifically, it includes a 2/M frequency divider 22 and a flip-flop 23 for 1/2 frequency division, obtains a pulse P _c obtained by dividing the clock pulse CP by 2/M from the frequency divider 22, and divides the clock pulse _CP by 2/M. The flip-flop 23 divides the frequency into 1/2. As a result, flip-flop 23
A square wave pulse P _b with a duty of 50% and a frequency of 1/M of the clock pulse CP is output from the output (Q) of the clock pulse CP, and the inverted output () of the pulse
A square wave pulse P _a which is the inversion of P _b is output. 180
The pulses P _b and P _a , which are out of phase with each other, are input to flip-flops 24 and 25 for 1/2 frequency division, respectively, and pulses 1/2 P _b and P _a , which are obtained by dividing these pulses P b and P _a by 1/2, respectively 1/2P _a is obtained. Therefore, each pulse
The relationships among CP, P _a , P _b , P _c , 1/2P _b , and 1/2P _a are shown in FIG. That is, the pulses 1/2P b and 1/2P _b output from each flip-flop 24 and 25
1/2P _a has a frequency of 1/2M of the clock pulse CP, and is 90 degrees out of phase with the clock pulse CP.

Each pulse 1/2P _b and 1/2P _a is input to low-pass filters 26 and 27, respectively, and their fundamental wave components are extracted. Therefore, if the signal output from the low-pass filter 26 is a cosine wave signal cosωt, the signal output from the low-pass filter 27 is a sine wave signal sinωt. low pass filter 2
The output cosωt of 6 is amplified by an amplifier 28, and the output Icosωt is applied to the primary windings 2B and 2D of one excitation pole pair B and D. low pass filter 2
2's output sinωt is amplified by an amplifier 24, and its output Isinωt is applied to the primary winding 2 of the other excitation pole pair A and C.
Applied to A and 2C.

The output signal E' of the position detector 13 is inputted to the polarity determining circuit 31 in the detection circuit 16 via the phase shift circuit 14 and the amplifier 30. The other polarity determining circuit 32 is supplied with a reference AC signal Isinωt from the amplifier 29. The polarity determination circuits 31 and 32 output "1" when the amplitude of the input signal (Ksin (ωt-θ), Isinωt) has positive polarity, and output "0" when the amplitude has negative polarity. The outputs of the polarity determining circuits 31 and 32 are input to rising edge detection circuits 33 and 34, respectively. The rise detection circuits 33 and 34 are monostable multivibrators, and when the input signal rises to "1",
Outputs short pulses. Therefore, as shown in FIG. 5, when the phase angle (ωt-θ) of the position detection signal E=Ksin(ωt-θ) is 0 degrees, the rise detection pulse T _S is output from the rise detection circuit 33, and the AC signal Isinωt
When the phase angle ωt of ωt is 0 degrees, the rise detection circuit 34 outputs a rise detection pulse T ₀ . The position detection signal E=Ksin(ωt−θ) lags behind the AC signal Isinωt by a phase angle corresponding to the rotational position θ. Therefore, after a time delay corresponding to the phase shift θ from the generation of the rising edge detection pulse T ₀ , the rising edge detection pulse T _S
is generated.

Using the counter 35, the rising edge detection pulse
Data corresponding to the phase shift θ can be obtained by counting the time difference between T ₀ and T _S. The oscillator 20 is connected to the count input of the counter 35.
A clock pulse CP oscillated from is given.
The reset input of the counter 35 is an excitation AC signal.
A pulse T ₀ indicating the 0 phase of Isinωt is given.
Therefore, the counter 35 counts the clock pulses CP, and the count is reset every 0 phase of the excitation AC signal Isinωt.

The output of the counter 35 is input to a buffer register 36. The sampling clock input of the buffer register 36 is the position detection signal Ksin (ωt−θ).
A pulse T _S indicating the 0 phase (ωt−θ=0) is given. When this pulse T _S occurs, the counter 35
The count contents are taken into the buffer register 36. Therefore, the buffer register 36 outputs the count value D〓 corresponding to the phase shift, that is, the position θ.
is output. The display section 17 (FIG. 1) displays the position of the detection target 12 based on this count value D.

FIG. 6 shows an example of the phase shift circuit 14. The phase shift circuit 14 consists of a resistor R ₁ , a variable resistor R ₂ , and a capacitor C, and outputs a signal E obtained by shifting the phase of the input signal E' by appropriately delaying the input signal E' according to the time constant of the circuit. Output. The time constant or phase shift of the circuit is adjusted by adjusting variable resistor _R2 . The resistance value of this variable resistor R ₂ is adjusted according to manual operation of the operating section 15.

In the example shown in FIG. 3, the detection circuit 16 obtains the position detection data in digital quantities, but the present invention is not limited to this, and the data may be obtained in analog quantities as shown in FIG.

In FIG. 7, the secondary winding 7 of the position detector 13
The output signal E' output from the polarity determining circuit 50 is inputted to the polarity determining circuit 50 via the phase shift circuit 14. Phase shift circuit 14
Assuming that the output signal E of is as shown in Fig. 8a,
The polarity determination circuit 50 outputs "1" in response to positive polarity and "0" in response to negative polarity, as shown in FIG. The rising edge detection circuit 51 includes a polarity discrimination circuit 5
Corresponding to the rising timing of output b of 0, a short pulse is output as shown in FIG. 8c. On the other hand, the reference AC signal Isinωt is input to the polarity discrimination circuit 52, and after being waveform-shaped as shown in FIG. The 1/2 frequency divider circuit 53 provides an output f that repeats "1" and "0" every cycle of the reference AC signal Isinωt, as shown in FIG. 8f. The output f of this 1/2 frequency divider circuit 53
is applied to the integrating circuit 54, and as shown in FIG. Get from. The output g of the integrating circuit 54 is input to a sample hold circuit 55 and sampled at the timing of the phase angle of 0 degrees of the position detection signal (FIG. 8a). That is, the output C of the rising edge detection circuit 51 is applied to the sampling control input of the sample hold circuit 55 via the gate 56. The gate 56 becomes conductive when the output f of the 1/2 frequency divider circuit 53 is “1” and outputs the output pulse C of the rise detection circuit 51.
is applied to the sample and hold circuit 55, but when f is "0", it functions to block the pulse C. The output f of the 1/2 frequency divider circuit 53 is “0”
In this case, as shown in FIG. 8g, the integration circuit 54
Since the slope of the output g is negative, a gate 56 is provided to prohibit sampling of this portion. Therefore, as shown in FIG. 8h, a sampling pulse h is applied via the gate 56 when the slope of the output g of the integrating circuit 54 is positive. In this way, sampling is performed every other cycle,
The sample and hold circuit 55 outputs an analog DC voltage V corresponding to the phase shift between the reference AC signal Isinωt and the position detection signal (ie, the machine position to be detected).

Incidentally, even when a resolver is used as the phase modulation type position detector 13, this invention can be implemented in the same manner as in the above embodiment. Further, this invention can be implemented not only in a detector for detecting rotational position but also in a phase modulation type position detector for detecting linear position in the same manner as in the above embodiment. Further, the oscillation circuit 18, the detection circuit 16, and the phase shift circuit 14 are not limited to those shown in FIGS. 3 and 6, but can be arbitrarily changed in design.

As explained above, according to this invention, the origin can be electrically adjusted by providing a phase shift circuit on the output side of the phase modulation type position detector. Therefore, even if it is not possible to mount the detector so that the origin of the detector and the origin of the detection target coincide, the installation error can be corrected by subsequent adjustment of the phase shift circuit, reducing the time and effort required during installation. can be significantly reduced. In addition, high-resolution detectors are greatly affected by even the slightest installation error, but with this invention, the phase shift circuit can cancel out installation errors, so there is no need to worry about the effects. This makes it ideal for high-resolution detectors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the phase modulation type position detection device according to this invention, and FIG.
FIG. 3 is a block diagram showing an example of the detection circuit and oscillation circuit in FIG. 1, and FIG. 3 is a timing chart showing the operation in the oscillation circuit shown in FIG. 3; FIG. 5 is a timing chart showing the operation in the detection circuit shown in FIG. 3;
6 is a circuit diagram showing an example of the phase shift circuit in FIG. 1, FIG. 7 is a block diagram showing another example of the detection circuit in FIG. 1, and FIG. 8 is a circuit diagram showing the operation of the detection circuit in FIG. 7. This is a timing chart. 1... Stator, 2A to 2D... Primary winding, 3
...Rotor, 4...Rotating shaft, A, B, C, D...
Excitation pole, 5, 6... Oscillator, 7, 7A to 7D...
Secondary winding, 13...Phase modulation type position detector, 14
... Phase shift circuit, 16 ... Detection circuit, 18 ... Oscillation circuit.

Claims (1)

[Claims for Utility Model Registration] A phase modulation type position detector that generates an output obtained by phase modulating a reference AC signal according to the position of an object to be detected, and a phase between the output signal of this detector and the reference AC signal. A detection circuit that detects a shift; and a variable phase shift circuit that shifts the output signal of the detector by a desired amount are provided between the detector and the detection circuit, and the amount of phase shift in the phase shift circuit is adjusted. 1. A phase modulation type position detection device comprising: an origin adjustment device that electrically adjusts an origin between a detection target and a detector.