JP4622067B2 - Ranging sensor failure detection apparatus and failure detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a failure detection device and failure detection method for a distance measuring sensor used in a magnetic bearing device for a rotating machine and an electromagnetic vibration control device for a steel plate.
[0002]
[Prior art]
In a magnetic bearing device for a rotating machine or an electromagnetic vibration control device for a steel plate, two distance measuring sensors are arranged opposite to each other with the control object sandwiched between them in order to detect the position of the control object such as a rotating shaft or steel plate. The position of the control object is measured from the difference signal of the sensor output, and control is performed so that the control object becomes a predetermined position.
[0003]
FIG. 8 is a block diagram showing the configuration of a conventional steel plate position / vibration control device. In this figure, an electromagnet 1 and an electromagnet 2 are arranged opposite to a steel plate 10 having a thickness t, and a distance measuring sensor 1a and a distance measuring sensor 2a are arranged at the same position as these electromagnets.
The distance measurement outputs y1 and y2 of the sensors 1a and 2a are input to the subtractor 3, and the difference output (y1-y2) is given to the position / vibration controller 4.
The position / vibration controller 4 controls the exciting currents of the electromagnet 1 and the electromagnet 2 so that the value of the differential output (y1-y2) of the subtractor 3 becomes zero, and holds the steel plate 10 at a predetermined position.
As shown in FIG. 9, when the sensor gain is A and the output offset is B as shown in FIG. 9, the relationship between the distance X and the sensor output y is generally
y = AX + B
Can be expressed as
[0004]
Further, in Japanese Patent Laid-Open No. 2000-109211, the difference between the displacement of the steel sheet front and back surfaces and the displacement of the steel sheet front and back surfaces measured by a displacement meter (corresponding to the distance measuring sensor described above) disposed on both surfaces of the steel sheet. A steel plate shape control device is disclosed in which the position of the steel plate is controlled while controlling the drive current of each electromagnet based on the inter-meter distance.
[0005]
Furthermore, in Japanese Patent No. 2557395, a mounting portion having a wall portion that forms the periphery of a through hole into which a rotating shaft such as a bearing is inserted is provided, and a plurality of hole portions formed at positions symmetrical to the axis of the through hole are provided. In addition, a magnetic bearing device is disclosed in which a displacement sensor, an oscillation circuit, and a filter circuit are integrally fitted with a peripheral edge as a reference.
[0006]
[Problems to be solved by the invention]
However, in these devices described above, even if the sensor fails and the obtained sensor gain changes, whether the change in the output value of the sensor is due to the change in the distance between the sensor and the steel plate, or the failure of the sensor itself. There was a problem that it could not be identified.
[0007]
The present invention has been made under such a background, and a failure detection device for a distance measurement sensor capable of reliably detecting a failure of the distance measurement sensor by monitoring an added value of the outputs of the two distance measurement sensors. And it aims at providing a failure detection method.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, two distance measuring sensors having the same characteristics are disposed opposite to each other with the control object interposed therebetween, and the distances from the control object by the two distance measuring sensors are respectively predetermined values. In the position control device for controlling the position of the control object,
Adding means for adding the outputs of the two distance measuring sensors;
Failure determination means for determining failure of the distance measuring sensor according to the addition result;
A failure detection device for a distance measuring sensor is provided.
[0009]
According to a second aspect of the present invention, in the failure detection device for the distance measuring sensor according to the first aspect,
The failure determination means determines that the distance measuring sensor has failed when the addition result deviates from a predetermined range.
[0010]
According to a third aspect of the present invention, two distance measuring sensors having the same characteristics are arranged opposite to each other with the control object interposed therebetween, and the distances from the control object by the two distance measuring sensors are respectively predetermined values. In the position control device for controlling the position of the control object,
Adding the outputs of the two distance measuring sensors;
A process of performing a failure determination of the distance measuring sensor due to the addition result deviating from a predetermined range;
A failure detection method for a distance measuring sensor is provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the basic configuration of a failure detection device for a distance measuring sensor according to an embodiment of the present invention.
In this figure, the distance measuring sensors 1a and 2a are arranged facing each other with a distance X0 across a steel plate 10 having a thickness t. When the distance between the sensor 1a and the steel plate 10 is X1, and the distance between the sensor 2a and the steel plate 10 is X2,
X1 + X2 = X0-t
It becomes.
[0012]
The output y1 of the sensor 1a and the output y2 of the sensor 2a are added by the adder 5, and the addition result is input to the failure determiner 6.
If the sensors 1a and 1b are normal, the added value by the adder 5 is twice the output value of each sensor corresponding to the average value (X1 + X2) / 2 of the distance between the steel plate 10 and each sensor.
That is, if the sensor gain is A and the output offset value is B,
{A (X0−t) / 2 + B} × 2 = y1 + y2
It becomes.
In addition, as FIG. 4 shows, it is the same even if it replaces the steel plate 10 with bearings 11, such as a magnetic bearing.
[0013]
For example, a case where (X1 + X2) = 1 mm in FIG. 1 will be described. At this time, if a sensor having characteristics as shown in FIG. 2 (A is 20 V / mm, B is −10 V, ie, y = 20X−10) is used, sensor outputs y1 and y2 with respect to the distance X1 with respect to the sensor 1a steel plate 10 Is as shown in FIG.
At this time, if the two sensors 1a and 1b are operating normally, the sum (y1 + y2) of the output values of the two sensors becomes 0 V regardless of the position X1 of the steel plate 10.
If the sum of output values (y1 + y2) does not become 0V, it can be determined that one of the sensors is malfunctioning.
[0014]
In reality, ranging sensors are rarely completely linear due to saturation characteristics and hysteresis characteristics, and are considered to have nonlinear characteristics. In order to avoid malfunctions of the detector due to these nonlinear characteristics, the output characteristics For the linear part of (or by approximating the output characteristic to the linear characteristic), a method for eliminating the erroneous determination by giving a range to the value that is determined to be normal is used.
The determination range for determining normality is determined in consideration of the nonlinear characteristics of the distance measuring sensor, the noise level, and the like. For example, it is determined that 0.8 to 1.1 times the reference value is normal, and a sensor failure is detected if it is outside this range.
[0015]
FIG. 5 is a block diagram showing the configuration of a steel plate position / vibration control device to which the above-described distance detection sensor failure detection device is applied.
This figure is different from the conventional steel plate position / vibration control device shown in FIG. 8 in that an adder 5 adds the output y1 of the sensor 1a and the output y2 of the sensor 2a, and a sensor failure is caused by this added output. This is a point to which a failure determination device 6 for determination is added.
The operation is as described above with reference to FIGS.
[0016]
FIG. 6 shows a configuration in which a low-pass filter (LPF) 7 is inserted on the output side of the adder 5 in FIG. 1. By passing the output signal of each sensor or its added value through the low-pass filter, sensor noise is reduced. It is possible to remove the influence and perform a stable detection operation.
In addition, as shown in FIG. 7, the same applies even if the steel plate 10 is replaced with a bearing 11.
[0017]
The operation of one embodiment of the present invention has been described in detail with reference to the drawings. However, the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Are also included in the present invention.
However, in the steel plate position / vibration control device, it is sufficient to control in one direction. However, in the magnetic bearing device, the rotation axis is predetermined although not described in detail in addition to the above-described distance detection means and addition means between the bearing and the sensor. In order to maintain and rotate at the position, it is necessary to individually control both ends of the rotating shaft in two directions orthogonal to the rotating shaft direction.
[0018]
【The invention's effect】
As described above, according to the present invention, the sensor failure is determined by monitoring the sum of the output signals of the two distance measuring sensors arranged opposite to each other. The effect that it can detect reliably is acquired.
[Brief description of the drawings]
FIG. 1 is a diagram showing a principle configuration of a steel sheet failure detection apparatus using a distance measuring sensor according to an embodiment of the present invention.
FIG. 2 is a diagram showing output characteristics of a distance measuring sensor.
FIG. 3 is a diagram showing an added value of outputs of two distance measuring sensors arranged opposite to each other.
FIG. 4 is a diagram showing the basic configuration of a magnetic bearing failure detection apparatus using a distance measuring sensor according to an embodiment of the present invention.
FIG. 5 is a block diagram showing the configuration of a steel plate position / vibration control device to which a distance detection sensor failure detection device according to an embodiment of the present invention is applied;
6 is a diagram showing a configuration in which a low-pass filter (LPF) 7 is inserted on the output side of the adder 5 of FIG. 1;
7 is a diagram showing a configuration in which a low-pass filter (LPF) 7 is modified on the output side of the adder 5 in FIG. 4;
FIG. 8 is a block diagram showing the configuration of a conventional steel plate position / vibration control device.
FIG. 9 is a diagram showing general output characteristics of a distance measuring sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 ... Electromagnet 1a, 2a ... Ranging sensor 3 ... Subtractor 4 ... Position / vibration controller 5 ... Adder 6 ... Failure determination device 7 ... LPF
10 ... steel plate

Claims (3)

When the sensor gain is A, the output offset is B, and the distance to the object to be measured is X, two distance measuring sensors with the same characteristics where the sensor output y is y = AX + B are opposed to each other with the control object sandwiched therebetween. In a position control device that arranges and controls the position of the control object such that the distance from the control object by the two distance measuring sensors becomes a predetermined value,
Adding means for adding the outputs of the two distance measuring sensors;
A failure detection unit for determining a failure of the distance measuring sensor based on the addition result; The failure determination means includes
The ranging sensor failure detection device according to claim 1, wherein when the addition result deviates from a predetermined range, the ranging sensor failure is determined. When the sensor gain is A, the output offset is B, and the distance to the object to be measured is X, two distance measuring sensors with the same characteristics where the sensor output y is y = AX + B are opposed to each other with the control object sandwiched therebetween. In a position control device that arranges and controls the position of the control object such that the distance from the control object by the two distance measuring sensors becomes a predetermined value,
Adding the outputs of the two distance measuring sensors;
A ranging sensor failure detection method comprising: a step of performing failure determination of the ranging sensor when the addition result deviates from a predetermined range.

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