JP2008175660A - Abnormality detecting device and position detector equipped with abnormality detecting part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detecting device for accurately detecting the abnormality of a detection signal in a simple processing circuit, and to provide a position detector provided with the abnormality detecting device. <P>SOLUTION: A Hilbert transformer 100 generates COS data, Hilbert-transformed SIN data from the SIN data which is the A/D-transformed sin signal output from a sensor 70. A data shift unit 101 generates COS' data giving delay corresponding to a delay part of the Hilbert transformer 100 to the COS data, the A/D-transformed cos signal output from the sensor 70. A judgement unit 103 calculates a deference between the COS data and the COS' data, and judges whether it is in a prescribed range or not. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an abnormality detection device that detects an abnormality of a detection signal of a position detector, and more particularly, to an abnormality detection device that detects an abnormality of a sin signal and a cos signal sent from a sensor to a position detector according to displacement of a moving body. And a position detector including an abnormality detector.

FIG. 7 is a block diagram of a conventional abnormality detection device.
In the figure, 30 is a resolver, and 40 is a rotation sensor signal processing circuit.
In the resolver 30, 31 is a rotating portion fixed to the rotor shaft, 32 is an excitation winding, 33 is a sin winding, and 34 is a cos winding. In the rotation sensor signal processing circuit 40, reference numerals 42, 43 and 44 denote wirings, 45 denotes an oscillation circuit, 46 denotes an R / D converter, 47 denotes a comparator, 48 and 49 denote A / D converters, and 50 denotes a control CPU.

Hereinafter, the operation of the prior art will be described with reference to FIG.
When the comparator 47 of the rotation sensor signal processing circuit 40 detects the peak of the reference signal from the transmission circuit 45, the comparator 47 performs A / D conversion on the sin signal and the cos signal from the resolver 30 at this peak timing, and an A / D converter 48. And the COS signal from the A / D converter 49 are input to the control CPU 50.

  The control CPU 50 has a built-in table in which sin θ and cos θ and θ are associated with each other, and estimates the angle θ by referring to this table with the values of the input SIN signal and COS signal. On the other hand, the control CPU 50 also receives an angle signal Θ obtained from the R / D converter 46. The control CPU 50 obtains the absolute value of the difference between the angle θ obtained by referring to the table and the angle Θ obtained from the R / D converter 46, and the obtained angle difference is a predetermined abnormality detection threshold value. It is determined whether or not it exceeds. When it is determined that the abnormality detection threshold value is exceeded, it is determined that an accurate angle signal Θ is not obtained from the R / D converter 46.

Further, the control CPU 50 obtains the sum of the square of the SIN signal and the square of the COS signal, and when SIN ² θ + COS ² θ = 1 is satisfied, it is normal. It was judged. (For example, see Patent Document 1)
Japanese Patent Laid-Open No. 9-72758

  Whether the angle difference between the angle signal obtained from the RD converter and the angle signal referring to the table with the values of the sin signal and the cos signal, which has been performed in the conventional abnormality detection device, exceeds a predetermined threshold value. This method requires a memory for creating a table and has a problem that the processing circuit becomes complicated. In addition, the method of calculating the sum of squares of detection signals has a problem that it is easily affected by fluctuations in detection voltage and cannot be detected with high accuracy.

  The present invention has been made in view of such problems, and provides an abnormality detection device capable of accurately detecting an abnormality of a sensor signal with a simple processing circuit and a position detector including the abnormality detection device. Objective.

In order to solve the above problems, the present invention is configured as follows.
The invention according to claim 1 is an abnormality detection device for detecting an abnormality in a sin signal and a cos signal output from a sensor in accordance with displacement of a moving body, wherein the abnormality detection device converts the sin signal into SIN data. A first A / D converter that performs A / D conversion, a second A / D converter that performs A / D conversion of the cos signal into COS data, and a COS obtained by shifting the phase of the SIN data by π / 2. A Hilbert transformer for calculating data, a data shifter for calculating COS ′ data obtained by adding a delay corresponding to the delay time of the Hilbert converter to the COS data, and a difference between the COS data and the COS ′ data. It is characterized by having a determination device for determining the presence or absence of the.
According to a second aspect of the present invention, the anomaly detection device includes a sign inverter that calculates -COS 'obtained by inverting the COS' data, and the determination unit includes between the COS ~ data and the COS 'data. A first coincidence discriminator for discriminating the presence or absence of a difference; a second coincidence discriminator for discriminating the presence or absence of a difference between the COS ~ data and -COS 'data; An OR gate for calculating a logical sum of two coincidence discriminators is provided.
The invention according to claim 3 is characterized in that the determination unit determines that an abnormality is detected when an abnormality signal is detected a plurality of times consecutively from the output of the logical sum.
According to a fourth aspect of the present invention, in the position detector for detecting the displacement of the moving body from the sin signal and the cos signal output from the sensor in accordance with the displacement of the moving body, the position detector includes position signal processing. A first A / D converter for A / D converting the sin signal into SIN data, and a second for A / D converting the cos signal into COS data. A / D converter, a Hilbert converter that calculates COS ~ data obtained by shifting the phase of the SIN data by π / 2, and a COS ′ that gives a delay corresponding to the delay time of the Hilbert converter to the COS data A data shifter that calculates data, and a determination unit that determines abnormality from the presence / absence of a difference between the COS ~ data and the COS 'data and the presence / absence of a difference between the COS ~ data and -COS' data. It is characterized in that was example.
According to a fourth aspect of the present invention, a servo motor includes the position detector according to the fourth aspect.

According to the invention described in claim 1, the anomaly detection apparatus includes a Hilbert transformer that performs Hilbert transform on SIN data, a data shifter that gives a delay corresponding to the delay time of the Hilbert transformer to COS data, a Hilbert transformer, and Since the determination device for determining whether there is a difference in output from the data shifter is provided, a highly accurate abnormality detection device can be realized with a simple configuration.
According to the second aspect of the present invention, if a sign inverter is provided, an abnormality can be detected regardless of the advance and delay of the sin signal and the cos signal.
According to the third aspect of the present invention, when an abnormality signal is detected continuously several times, the abnormality detection device that is less susceptible to noise can be realized if it is determined to be abnormal.
According to the invention described in claim 4, the position detector includes a position signal processing unit and an anomaly detection unit, and the anomaly detection unit performs a Hilbert transformer that converts the SIN data into a Hilbert transform, and a delay of the Hilbert transformer into the COS data. Since it has a data shifter that gives a delay corresponding to time, and a determiner that determines whether there is a difference in output from the Hilbert transformer and the data shifter, a position detector that can detect anomalies with high accuracy with a simple configuration Can be realized.
According to the invention described in claim 5, since the servo motor is provided with the position detector described in claim 4, an abnormal signal can be quickly sent out in the event of an abnormality, and the reliability of the control system using this servo motor is improved. .

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an abnormality detection apparatus showing a first embodiment of the present invention.
In the figure, 11 is a first A / D converter that converts the sin signal sent from the sensor unit 70 into SIN data at a constant sampling period, and 12 is a second A / D converter that converts the cos signal into COS data. It is a vessel. Reference numeral 100 denotes a Hilbert transformer that performs Hilbert transform on SIN data, 101 denotes a data shifter that performs temporal shift of COS data, and 103 denotes a determination unit. The Hilbert converter 100, the data shifter 101, and the determination unit 103 are configured by a control CPU 50.

First, the configuration and operation of the Hilbert transformer 100 will be described.
FIG. 2 is a configuration diagram of the Hilbert transformer in this embodiment.
In the figure, 104 is a delay unit, 105 is a multiplier, and 106 is an adder.
The digital signal value of the input SIN data at time t is expressed as Xt [0], and the digital signal value delayed by one sample by the delay unit 104 and delayed by the total number of delay units n−1 is Xt [n. -1]. Also, the Hilbert transform coefficient sequences are denoted as K [0] .. K [n-1], respectively.

The Hilbert transformer 100 uses a multiplier 105 and an adder 106, and from the digital signal values Xt [0]... Xt [n-1] and the Hilbert transform coefficients K [0] .. K [n-1]. (1) The equation is calculated.
Yt = ΣK [i] × Xt [i], i = 0 to (n−1) (1)
The output Yt is data having linear phase characteristics with respect to the SIN data, and is hereinafter referred to as COS˜data.

Next, the configuration and operation of the data shifter will be described.
FIG. 3 is a configuration diagram of a data shifter of the abnormality detection device in this embodiment.
In the figure, reference numeral 104 denotes a delay device. The input COS data is delayed by N = (n−1) / 2 samples. However, (n: filter tap length of the Hilbert converter).

  When COS data at time t is expressed as Dt [0], COS data delayed by one sample is expressed as Dt [1], and data delayed by N samples is expressed as Dt [N], data output from the data shifter 101 is expressed as Dt [ N] is data obtained by adding a delay corresponding to the delay of the Hilbert transformer having the filter tap length n to the COS data. Hereinafter, this data is referred to as COS ′ data.

  As described above, the data shifter has the same delay as the delay due to the SIN data passing through the Hilbert transformer 100 with respect to the COS data so that the COS ~ data and the COS ′ data have the same phase. Yes.

Next, the abnormality determination operation will be described.
In FIG. 1, COS data obtained by the Hilbert transformer 100 and COS ′ data obtained by the data shifter 101 are input to the determination unit 103. The determiner 103 calculates the difference between the COS ~ data and the COS ′ data, and determines whether or not it is within a predetermined range.
If it exceeds the predetermined range, it is determined that an abnormality has occurred in at least one of the sin signal and the cos signal. In order to avoid malfunction due to noise, it may be determined that an abnormality has occurred when a predetermined range has been exceeded a plurality of times.

  As described above, in this embodiment, since abnormality detection is not accompanied by angle calculation, abnormality detection can be realized with a simple processing circuit. Also, rather than simply calculating the sum of the squares of the sin signal and the cos signal, it is determined whether there is a difference between the COS ~ data generated based on the sin signal and the COS ′ data generated based on the cos signal. Therefore, it is possible to realize highly accurate abnormality detection that is not easily affected by fluctuations in the detection voltage.

FIG. 4 is a block diagram of an anomaly detection apparatus showing a second embodiment of the present invention, and FIG. 5 is a block diagram of a determiner in the present embodiment.
In FIG. 4, reference numeral 102 denotes a sign inverter, and 103 ′ denotes a determiner. In FIG. 5, 108a is a first coincidence discriminator, and 108b is a second coincidence discriminator. This embodiment is different from the first embodiment in that the abnormality detection apparatus 10 includes a sign inverter 102 that calculates −COS ′ obtained by inverting COS ′ data, and that the determiner 103 ′ includes COS˜data. , A first coincidence discriminator 108a for discriminating whether or not there is a difference between COS ′ data, and a second coincidence discriminator 108b for discriminating the presence or absence of a difference between COS˜data and −COS ′ data. It is.

Next, the operation of this embodiment will be described.
In FIG. 5, the coincidence discriminator 108 a calculates the difference between the COS˜ data and the COS ′ data, and if it is within a predetermined value, outputs “1” because both signals coincide with each other. Further, the coincidence discriminator 108b calculates the difference between the COS ~ data and the -COS 'data, and if it is within a predetermined value, it outputs "1" because both signals coincide. An OR gate 109 outputs an OR signal of the output signals of the coincidence discriminator 108a and the coincidence discriminator 108b.

  When the sine signal is 90 degrees ahead of the cosine signal when the sine signal and the cosine signal are normal, the COS ~ data and the COS ′ data are in phase, and the coincidence discriminator 108a outputs “1”. When the sin signal is delayed by 90 degrees from the cos signal, the COS ~ data and the -COS 'data are in phase, and the coincidence discriminator 108b outputs "1". Since the OR gate 109 outputs the OR signals of the coincidence discriminator 108a and the coincidence discriminator 108b, "1" is output regardless of the advance and delay of the sin signal and the cos signal. Therefore, in this embodiment, an abnormality can be detected regardless of the advance and delay of the sin signal and the cos signal.

FIG. 6 is a block diagram of a position detector showing a third embodiment of the present invention.
In the figure, 13 is a position signal processing unit, and 10 'is an abnormality detection unit. The position detector 20 includes a position signal processing unit 13 and an abnormality detection unit 10 ′.
The position signal processing unit 13 controls the position detection signal θ according to the displacement of the moving body from the sin signal and the cos signal output according to the displacement of the moving body (not shown) detected by the sensor unit 70. Output to the device. Further, the abnormality detection unit 10 ′ includes the abnormality detection device shown in the second embodiment, determines whether the sin signal and the cos signal are normal, and uses the determination signal e as an upper control device ( (Not shown).

  As described above, in the present embodiment, the position detector includes the position signal processing unit and the abnormality detection unit using the Hilbert transformer, so that the position detector has a simple structure and a highly accurate abnormality detection function. Can be realized.

  The method of detecting the angle difference between the angle signal obtained from the RD converter shown in the prior art and the angle signal referring to the table with the values of the sin signal and the cos signal is a method of detecting an abnormality of the angle signal. As a result, it took time to output the abnormality detection signal. In the present embodiment, the position detector can generate an abnormality detection signal from SIN data and COS data by a simple calculation using a Hilbert transformer and a data shifter, so that the abnormality detection signal can be transmitted quickly with a short calculation time. Therefore, when the position detector of the present embodiment is applied to a servo motor, an abnormal signal can be quickly transmitted in the event of an abnormality, and the reliability of a control device using this servo motor is improved.

  The present invention can also be applied to disconnection detection or short circuit detection of an angle measuring device such as a resolver or encoder, and to detection of disconnection or short circuit of a sensor using two-phase signals of a sine wave signal and a cosine wave signal as detection information.

1 is a block diagram of an abnormality detection apparatus showing a first embodiment of the present invention. It is a block diagram of the Hilbert converter in a present Example. It is a block diagram of the data shifter of the abnormality detection apparatus in a present Example. It is a block diagram of the abnormality detection apparatus which shows 2nd Example of this invention. It is a block diagram of the determination device in a present Example. It is a block diagram of the position detector which shows 3rd Example of this invention. It is a block diagram of the conventional abnormality detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Abnormality detection apparatus 10 'Abnormality detection part 100 Hilbert transformer 101 Data shifter 102 Sign inverter 103, 103' Judgment device 104 Delay device 105 Multiplier 106 Adder 108a, 108b Match discrimination device 109 OR gate 11, 12 A / D converter 13 Position signal processing unit 20 Position detector 30 Rotation sensor signal processing circuit 31 Rotating portion 32 fixed to the rotor shaft Excitation winding 33 Sin winding 34 Cos windings 42, 43, 44 Wiring 45 Transmission circuit 46 R / D converter 47 Comparator 48, 49 A / D converter 50 Control CPU
70 Sensor part 72 Position signal processing part

Claims (5)

An abnormality detection device that detects an abnormality in a sin signal and a cos signal output from a sensor according to displacement of a moving body,
The abnormality detection device includes: a first A / D converter that A / D converts the sin signal into SIN data; a second A / D converter that A / D converts the cos signal into COS data; A Hilbert transformer that calculates COS ~ data obtained by shifting the phase of the SIN data by π / 2; a data shifter that calculates COS ′ data obtained by adding a delay corresponding to the delay time of the Hilbert transformer to the COS data; An anomaly detection apparatus comprising: a determination unit that determines whether or not there is a difference between the COS ~ data and the COS ′ data.   The abnormality detection apparatus includes a sign inverter that calculates −COS ′ obtained by inverting the COS ′ data, and the determination unit determines a first match determination that determines whether there is a difference between the COS˜data and the COS ′ data. A logical sum of a second match discriminator, a second match discriminator for discriminating whether or not there is a difference between the COS ~ data and -COS 'data, and a second match discriminator. 2. The abnormality detection device according to claim 1, further comprising an OR gate.   3. The abnormality detection device according to claim 2, wherein the determination unit determines that an abnormality is detected when an abnormality signal is detected continuously a plurality of times from the output of the logical sum. In the position detector that detects the displacement of the moving body from the sin signal and the cos signal output from the sensor according to the displacement of the moving body,
The position detector includes a position signal processing unit and an abnormality detection unit,
The abnormality detection unit includes: a first A / D converter that A / D converts the sin signal into SIN data; a second A / D converter that A / D converts the cos signal into COS data; A Hilbert transformer that calculates COS ~ data obtained by shifting the phase of the SIN data by π / 2; a data shifter that calculates COS ′ data obtained by adding a delay corresponding to the delay time of the Hilbert transformer to the COS data; A position detector comprising: a determination unit that determines whether there is a difference between the COS ~ data and the COS 'data and a difference between the COS ~ data and the -COS' data.   A servo motor comprising the position detector according to claim 4.

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