JP6257957B2 - Magnetic field measuring device - Google Patents

Description

  The present invention relates to a magnetic field measuring apparatus that measures a magnetic field of each part of an object using a probe equipped with a three-axis magnetic field sensor and prevents damage due to a collision with each part of the probe.

  An apparatus has been developed that uses a probe equipped with a three-axis magnetic field sensor to accurately measure the magnetic field of each part of an object (Patent Document 1). Various techniques for detecting a positional relationship with an object or preventing a collision when an arm or a probe is moved close to the object have been introduced (Patent Documents 2 to 4).

Patent Document 1 Japanese Patent No. 4972568 Patent Document 2 Japanese Patent Laid-Open No. 2000-221201 Patent Document 3 Japanese Patent Application Laid-Open No. 2003-273175 Patent Document 4 Japanese Patent Application Laid-Open No. 2008-215934

The known prior art has the following problems to be solved.
A probe for measuring a triaxial magnetic field is composed of a ceramic substrate having a magnetic field sensor mounted on one end. While moving the magnetic field sensor along the surface of the object, a near magnetic field of the object is detected and a detection signal is transmitted to the measurement circuit (Patent Document 1).

  Here, when the operation of detecting the near magnetic field by causing the magnetic field sensor to approach the object is repeated, the end of the probe may collide with the object. Also, the drive device may be accidentally operated in the direction in which the obstacle is present, causing the probe to collide with the obstacle. Since the probe is vulnerable to bending, it will break if it is forcibly moved after a collision.

  Various mechanisms for avoiding a collision are introduced in the devices described in known patent documents, but it is difficult to adopt them as they are in the magnetic field measuring device. That is, a magnetic field sensor is mounted at the tip of the probe, and a sensor for avoiding a collision cannot be incorporated in that portion. Further, in order to increase the magnetic field measurement accuracy, it is not possible to place a foreign object near the tip of the probe.

  Furthermore, it is conceivable to arrange a reinforcing material that reinforces the probe. However, if the entire probe becomes thick, it becomes impossible to measure the magnetic field in a narrow recess. Therefore, it is desirable to use the probe as thin and thin as possible. Also, when the tip of the probe collides with something, it may be possible to support the probe softly to prevent damage to the probe. Measurement cannot be performed.

In order to solve the above problems, an object of the present invention is to provide a magnetic field measuring apparatus as follows.
(1) Avoid damage to the probe when the tip of the probe on which the magnetic field sensor is mounted collides with something.
(2) After the tip of the probe collides with something, the position is automatically returned to the stable position, and the measurement conditions are reliably reset.

  The following configurations are means for solving the above-described problems.

<Configuration 1>
A probe mounted at the tip with a magnetic field sensor for measuring magnetic fields in three axial directions orthogonal to each other;
A support part for supporting the probe via a connecting part;
A driving device that moves the tip of the probe in any of the XYZ axial directions that are mechanically set in a state where the support portion is held by a clamp;
A measuring device that acquires an output signal of the three-axis magnetic field sensor that measures a magnetic field near the surface of the object,
In the connecting part,
When the tip of the probe is moved in any of the XYZ axis directions, when an external force in the direction opposite to the moving direction is applied, the tip of the probe is absorbed by a certain amount in the direction of absorbing the external force. A holder for retracting,
A magnetic field measuring apparatus comprising: a stop control device for detecting a backward movement of the tip of the probe and urgently stopping the driving device.

<Configuration 2>
When the probe has an elongated plate shape that is thin compared to its width, the probe tip is retracted by a fixed amount in a certain direction only when an external force is applied to the probe tip in the thickness direction of the probe. The magnetic field measuring apparatus according to Configuration 1, further comprising a holder for causing the magnetic field to be measured.

<Configuration 3>
When the probe is in the shape of an elongated plate that is thinner than its width, the tip of the probe is fixed in a certain direction only when an external force is applied to the probe tip in the longitudinal or thickness direction of the probe. The magnetic field measuring apparatus according to Configuration 1, further comprising a holder that is retracted by a certain amount.

<Configuration 4>
The connecting part is
When a force is not applied to the tip of the probe, the tip of the probe is always held at a fixed position when viewed from the support mechanism, and the force is released after an external force is applied to the tip of the probe. The magnetic field measuring apparatus according to any one of the first to third aspects, further comprising a return mechanism that returns the tip of the probe to the original position.

<Configuration 5>
The holder is supported by a support portion by a support shaft that allows only a certain amount of linear movement in the Z-axis direction, and the holder rotates by a certain angle about the support shaft, and the probe Is supported to allow a certain amount of movement in the X-axis direction of the tip of the
The stop control device detects any state when the holder moves a certain amount in the Z-axis direction and when the holder rotates by a certain angle, and causes the drive device to stop urgently. The magnetic field measuring apparatus described.

<Configuration 6>
The stop control device transmits a signal for requesting resetting of the position coordinates in the measurement system of the tip of the probe to the measurement device when the drive device is urgently stopped. The magnetic field measurement apparatus according to any one of 2 to 4.

<Configuration 7>
A probe on which a magnetic field sensor for measuring magnetic fields in three axial directions orthogonal to each other is mounted at the tip, a support part for supporting the probe via a connecting part, and a signal cable;
In the connecting part,
When the tip of the probe is moved in any of the XYZ axis directions, when an external force in the direction opposite to the moving direction is applied, the tip of the probe is absorbed by a certain amount in the direction of absorbing the external force. And a detection device for detecting the retreat of the tip of the probe,
The signal cable is
The three-axis magnetic field sensor transmits an output signal obtained by measuring a magnetic field to a measuring device, and transmits the output signal of the detection device to a driving device that moves the tip of the probe. Parts of the magnetic field measuring device.

<Effect of Configuration 1>
For example, the tip of the probe is moved in the Z-axis direction, and the magnetic field sensor is set at a place where the magnetic field is to be measured. At this time, if the probe is moved excessively, the probe may collide with something. In addition, when the movement in the Z-axis direction is completed and the probe is moved in the X-axis direction to start the magnetic field measurement, the tip of the probe may collide with something. Thus, when the probe tip collides with something and an external force is applied, the holder functions as a buffer so as to absorb the external force. The stop control device detects that the holder has retracted and causes the drive device to stop urgently. In this way, damage to the probe can be prevented.
<Effect of Configuration 2>
When the probe has an elongated plate shape that is thinner than the width, the risk of breakage due to an external force in the thickness direction is highest. In addition, it is easier to return to the original position more accurately if it is supported so that it can be retracted by a certain amount only in one direction than it is supported so that it can be retracted in all directions.
<Effect of Configuration 3>
Assuming that the longitudinal direction of the probe is the Z-axis direction and the thickness direction is the X-axis direction, at the time of magnetic field measurement, the probe tip is moved by a certain amount only in this direction. Therefore, if the structure is configured to retreat only with respect to the external forces in the Z-axis direction and the X-axis direction, it is easier to accurately return to the original position than to support softly so that it can be retreated in an arbitrary direction.
<Effect of Configuration 4>
If the probe is supported too loosely, the position of the tip of the probe becomes unstable and the measurement accuracy decreases. Moreover, even if the position of the tip of the probe moves each time the tip of the probe collides with something, the measurement accuracy similarly decreases. Moreover, it is not easy to manually return to the original state. A mechanism for always returning the tip of the probe to a constant stable position when viewed from the support mechanism is provided.
<Effect of Configuration 5>
If the holder is supported so as to move only in a specific direction and its activation is detected by a switch, the holder can be operated reliably and a malfunction can be prevented.
<Effect of Configuration 6>
Even if the probe collides with something and returns to the original state, it is unclear whether the probe has completely returned to the original state. Therefore, it is necessary to check the sensor position again and reset the measurement conditions. You may request it from the device. The measurement apparatus may automatically set the measurement conditions by a method as shown in Patent Document 1, or may display a message so as to reset the measurement conditions to the operator of the apparatus. .

It is the principal part perspective view of the apparatus of an Example, and the block diagram of the apparatus connected to this. It is explanatory drawing about an external force and its absorption effect | action. It is a front view of the internal structure which shows the specific example of the said connection part. It is explanatory drawing of the return mechanism to the original state with the rotation support structure of the holder.

  Hereinafter, embodiments of the present invention will be described in detail for each example.

FIG. 1 is a perspective view of a main part of an apparatus according to an embodiment and a block diagram of an apparatus connected thereto.
The magnetic field measuring apparatus 12 shown in the figure includes a probe 14 for measuring a magnetic field. A magnetic field sensor 16 for measuring magnetic fields in three axial directions orthogonal to each other is mounted on the tip 30 of the probe 14. Since the magnetic field sensor 16 is very small, it is embedded in the tip 30 of the probe 14. In this figure, it is shown in a circle of a one-dot chain line.

  The probe 14 is supported by being integrated with the support portion 20 via the connecting portion 18. A signal cable 22 is drawn out from the upper end of the support portion 20 and is electrically connected to the main body of the magnetic field measuring apparatus 12. The main body of the magnetic field measuring device 12 is provided with a driving device 24, a measuring device 28, and a stop control device 36. Various other devices are provided, but only those necessary for the description of the present embodiment are shown.

  The signal cable 22 is used to transmit an output signal obtained by measuring the magnetic field by the magnetic field sensor 16 to the measuring device 28, or to transmit an output signal of a device for detecting a collision of the probe to the driving device 24. .

  The main body device has a function of moving the tip 30 of the probe 14 in a state where the support portion 20 is gripped by the clamp 26. The moving direction is set mechanically. The driving device 24 can move the probe 14 only in the designated direction of the XYZ axis directions indicated by the arrows on the right side of the clamp 26 in the drawing.

  With this device, it is possible to measure the magnetic field intensity on the XYZ coordinates, display the magnetic field distribution in the vicinity of the object, and examine how the object is magnetized. The measuring device 28 is a device that acquires an output signal of the three-axis magnetic field sensor 16 that measures a magnetic field near the surface of the object 32.

  When the tip 30 of the probe 14 is moved in any of the XYZ axial directions, an external force in a direction opposite to the moving direction is applied when it collides with an obstacle such as a wall or protrusion of the object. The connecting portion 18 retracts the tip 30 of the probe 14 by a certain amount (dX or dZ) in the direction of absorbing this external force. The stop control device 36 has a function of detecting the backward movement of the tip 30 of the probe 14 and urgently stopping the drive device 24.

FIG. 2 is an explanatory diagram of an external force and its absorption action.
For example, consider the case where the internal magnetic field of the recess 34 of the object 32 is measured as shown in FIG. At this time, the probe 14 is moved in the Z-axis direction and stopped in the state shown in the figure. If the timing for stopping the probe 14 by mistake is delayed, the tip 30 of the probe 14 collides with the wall surface of the recess 34. At this time, the connecting portion 18 (FIG. 1) retracts the tip 30 of the probe 14 by dZ. If this certain amount of backward movement is detected and the movement of the probe 14 is urgently stopped, the probe 14 can be prevented from being damaged.

  Also, consider the case where the probe 14 is moved in the X-axis direction inside the recess 34 of the object 32 as shown in FIG. If the position to be moved in the left direction in the figure is mistakenly moved in the right direction in the figure, the tip 30 of the probe 14 collides with the wall surface of the recess 34, and an external force in the direction of bending the probe 14 is applied. At this time, the connecting portion 18 (FIG. 1) retracts the tip 30 of the probe 14 by dX. If this certain amount of backward movement is detected and the movement of the probe 14 is urgently stopped, the probe 14 can be prevented from being damaged.

  The movement of dZ is a linear motion of the probe 14 in the Z-axis direction. On the other hand, the movement of dX is a rotational movement in the X-axis direction with the connecting portion 18 as an axis. A mechanism that is always fixed at a fixed position and that supports the connecting portion 18 using a guide or a bearing is preferable so as to allow the backward movement of the probe 14 when it collides with an obstacle. The connecting portion 18 of the following embodiment is configured to allow such backward movement.

  Moreover, as shown in FIG. 1, the probe 14 of this embodiment has an elongated plate shape that is thinner than the width. Therefore, when an external force is applied to the tip 30 of the probe 14 in the thickness direction of the probe 14, the probe 14 is most easily broken. Further, an operation error is most likely to occur in the state shown in FIG. Therefore, a structure may be adopted in which the tip 30 of the probe 14 is retracted by a fixed amount dX only in the Y-axis direction.

  If supported so that it can be retracted in all directions, the position of the tip 30 of the probe 14 may flutter due to vibration or the like, which may adversely affect measurement accuracy. Accordingly, it is preferable to have a structure in which the probe 14 is retracted only in the minimum direction necessary for protecting the probe 14, that is, only in the X-axis direction, or only in two directions of the X-axis and Z-axis directions. In addition, the structure for returning to the original position can be made simpler and more reliable.

FIG. 3 is a front view of the internal structure showing a specific example of the connecting portion 18.
As shown to (a) of a figure, the holder 40 and the limit switch 38 are integrated in the connection part 18. As shown in FIG. The signal cable 22 is fixed to the upper part of the support portion 20. The support shaft 42 and the spring 46 are fixed to the inner wall of the support portion 20. The holder 40 passes through the support shaft 42 through the long hole 44, and is supported in a state where it is pressed against the limit switch 38 by receiving a force from below to above with a spring 46.

  Thus, in this embodiment, the holder 40 is supported on the support portion 20 by the support shaft 42 that allows only a certain amount of linear movement in the Z-axis direction. The limit switch 38 does not operate with the elasticity of the spring 46. As shown in (b) of the figure, when the probe 14 receives an external force in the arrow direction (Z-axis direction) from the bottom to the top, the holder 40 is retracted upward by the length of the long hole 44.

  At this time, the limit switch 38 operates and sends a detection signal to the stop control device 36 through the signal cable 22. The stop control device 36 stops the operation of the drive device 24 immediately. Since the holder 40 is movably supported by the support portion 20 in this way, the output signal of the magnetic field sensor 16 is drawn into the signal cable 22 from the upper end of the probe 14 via a flexible signal line.

FIG. 4 is an explanatory diagram of a mechanism for returning the holder 40 to its original state with the rotation support structure. FIG. 4A is an enlarged side view of the holder 40 and the limit switch 38. (B) is a principal part side view when the holder 40 carries out rotational movement.
As shown in (b) of the figure, the holder 40 is supported so as to allow a certain amount of movement of the tip 30 of the probe 14 in the X-axis direction by rotating by a certain angle around the support shaft 42. ing. During this movement, the spring 46 expands and contracts, and the support shaft 42 moves up and down in the long hole 44. The rotational movement of the holder 40 operates the limit switch 38.

  Further, the protrusion 50 of the limit switch 38 is fitted into the notch 48 provided in the holder 40 in the center stable state of FIG. When the holder 40 rotates, the protrusion 50 rises from the notch 48 as shown in the left and right views of FIG. As a result, the limit switch 38 operates. Furthermore, the holder 40 is pushed back to the original state by the action of the spring 46. At the same time, the protrusion 50 of the limit switch 38 is fitted into the notch 48.

  As a result, the tip 30 of the probe 14 can always be held at a fixed position when viewed from the support mechanism in a state where no force is applied to the tip 30 of the probe 14. That is, the mechanism of the holder 40 functions as a return mechanism that returns the tip 30 of the probe 14 to the original position when the force is released after an external force is applied to the tip 30 of the probe 14.

  If the probe 14 is loosely supported so that it can be freely retracted, the position of the tip 30 of the probe 14 becomes unstable, and the measurement accuracy decreases. Further, every time the tip 30 of the probe 14 collides with something, if the position of the tip 30 of the probe 14 moves, it must be manually returned to the original state. Providing a mechanism for automatically returning to a certain stable position in this way solves this problem.

  As described in Patent Document 1, accurate measurement cannot be performed unless the position and inclination of the magnetic field sensor 16 are controlled with high accuracy. If it cannot be confirmed whether or not the tip 30 of the probe 14 has automatically returned to the original state after the collision, it is preferable to reset the position coordinates in the measurement system. Therefore, after the stop control device 36 performs the emergency stop control of the drive device 24, it is preferable to display the fact on, for example, a display (not shown) of the device. If the stop control device 36 transmits a signal for requesting resetting, the display control thereafter may be performed by the measuring device 28 or the like.

DESCRIPTION OF SYMBOLS 12 Magnetic field measuring device 14 Probe 16 Magnetic field sensor 18 Connection part 20 Support part 22 Signal cable 24 Drive device 26 Clamp 28 Measuring device 30 Tip 32 Object 34 Recess 36 Stop control device 38 Limit switch 40 Holder 42 Support shaft 44 Long hole 46 Spring 48 Notch 50 Protrusion

Claims (2)

A probe mounted at the tip with a magnetic field sensor for measuring magnetic fields in three axial directions orthogonal to each other;
A support part for supporting the probe via a connecting part;
A driving device that moves the tip of the probe in any of the XYZ axial directions that are mechanically set in a state where the support portion is held by a clamp;
A measuring device that acquires an output signal of the three-axis magnetic field sensor that measures a magnetic field near the surface of the object,
When the tip of the probe is moved in any of the XYZ axial directions to the connecting portion, when an external force in a direction opposite to the moving direction is applied, the connecting portion is constant in a direction to absorb the external force. Provide a holder that retracts the tip of the probe by an amount ,
A signal that detects the retreat of the tip of the probe by the external force, stops the driving device urgently, and requests the measurement device to reset the position coordinates in the measurement system of the probe tip. A magnetic field measuring apparatus comprising a stop control device for transmission . If the probe is a thin elongated plate shape thicker than the width, with respect to the distal end of the probe, only when an external force is applied to the longitudinal or thickness direction of the probe, the external force the tip of the probe The magnetic field measuring apparatus according to claim 1, further comprising a holder that is retracted by a certain amount in the absorption direction .

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