JPH0758190B2 - Normal detector - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a normal detector which measures, for example, a free-form surface of a three-dimensional solid surface and obtains a normal line of the surface to be measured.

2. Description of the Related Art Conventionally, when teaching an arbitrary point on a free-form surface of a three-dimensional solid surface such as a mold, in order to measure the normal direction at that point, for example, a normal ruler is applied to the point to measure the normal axis of the point. The normal direction is obtained by measuring the rotational displacement. However, since the measurement of the rotational displacement uses a potentiometer, a differential transformer, etc., some torque is required to rotate the measurement axis of the normal ruler at the time of measurement, and it is relatively Due to the large construction, it is difficult to incorporate in a small space.

Furthermore, a normal line detector that uses the attractive force of a magnet is also known, but this system uses a strain gauge or the like to detect the normal line, so the output signal is weak. , Requiring a high-sensitivity amplifier, etc.
There was a drawback.

OBJECTS OF THE INVENTION Accordingly, the object of the present invention is to provide a simple and compact configuration,
Moreover, it is to realize a normal detector which has a small operating torque in the differential operation, has a good responsiveness, and has a small error.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a measuring rod having a magnet at one end and a counterbalance attached at the other end, and an X-axis orthogonal to the central axis of the measuring rod and its center of gravity. The inner support frame that rotatably supports the measuring rod and has a common center of gravity with the measuring rod, and the inner side that is rotatable about the Y axis that is orthogonal to the X axis and that passes through the center of gravity of the measuring rod. An outer support frame that supports the support frame and is fixedly supported, a first sensor that measures a rotational displacement of the measuring rod with respect to the inner support frame with respect to the X axis, and a Y axis of the inner support frame with respect to the outer support frame. A second sensor for measuring the rotational displacement of the gimbal mechanism having two degrees of freedom.

When the magnet of the measuring rod approaches the surface to be measured of the magnetic substance and an attractive force acts between the magnet and the surface to be measured, the measuring rod rotates around the X axis and the Y axis with respect to the outer supporting frame. The normal amount of the surface to be measured is detected by measuring the amount of rotational displacement by the first and second sensors.

Preferably, the normal detector according to the present invention is provided with a pointer at the tip of the magnet attached to the measuring rod,
A contact made of a material having electric conductivity or contact pressure detection performance, such as a capacitance type sensor or conductive rubber, which detects when the tip of the pointer touches the surface to be measured or when it reaches a predetermined distance. The sensor is installed on the measuring rod, or the tip of the magnet attached to the measuring rod is equipped with the pointer of the conductive material, and a relatively low voltage is applied between the measured surface of the magnetic body and the measuring rod. Has been done,
When the tip of the pointer touches the surface to be measured, the conduction current generated between the surface to be measured and the measuring rod is measured, and a signal is output to output a signal, thereby allowing the magnet to approach the surface to be measured at an appropriate distance. It is designed to detect

Configuration of Embodiments Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

1 and 2 show the essential parts of a magnet type normal detector 1 according to the present invention. The measuring rod 2 has a magnet 3 at the lower end and a counter balance 4 at the upper end. At the center of gravity on the center line of the measuring rod 2, the inside of the measuring rod 2 via the X-axis shaft 5 fixed to the measuring rod 2. It is rotatably supported by the support frame 6 around the orthogonal X axis.
As described above, a pointer 3a is attached to the tip of the magnet 3 in order to detect the approach of the surface S to be measured of the measuring rod 2 at an appropriate distance. The inner support frame 6 has a common center of gravity with the measuring rod 2 and is rotatable about a Y axis that is orthogonal to the X axis and passes through the center of gravity of the measuring rod 2. Y-axis shaft 7 fixed to
It is supported by the outer supporting frame 8 via. Outer support frame 8
Are fixedly supported by a support arm 9 on a support portion (not shown). In this way, the measuring rod 2 is supported by the outer supporting frame 8 in the X-axis and Y-axis directions by the gimbal mechanism having two degrees of freedom. Therefore, when the magnet 3 approaches the measured surface S of the magnetic body during measurement,
Due to the attractive force of the magnet 3, the measuring rod 2 becomes perpendicular to the surface S to be measured as shown in FIG.

Further, an angular displacement sensor 10x for measuring the rotational displacement of the X-axis shaft 5 is fixedly arranged with respect to the inner support frame 6 near one of the support portions of the X-axis shaft 5 of the inner support frame 6, An angular displacement sensor 10y for measuring the rotational displacement of the Y-axis shaft 7 is fixedly arranged with respect to the outer support frame 8 in the vicinity of one of the support portions of the Y-axis shaft 7 of the outer support frame 8. .

The pointer 3a is related to the contact sensor 3b provided on the measuring rod 2, and when the tip of the pointer 3a contacts the surface S to be measured, the contact sensor 3b detects it. There is. As the contact or non-contact sensor 3b, a member having electric conductivity or contact pressure detection performance such as a capacitance type sensor or conductive rubber is preferably used. According to another embodiment, the pointer 3a is made of a conductive material, a relatively low voltage is applied between the measured surface S of the magnetic body and the measuring rod 2, and the tip of the pointer 3a is the measured surface. When it comes into contact with S, the conduction current generated between the surface S to be measured and the measuring rod 2 is measured and a signal is output. In this way, when measuring in the normal direction of the surface S to be measured, first, as shown in FIG.
When is located at an appropriate distance D from the surface S to be measured, the contact sensor 3b can detect the appropriate distance D.

The above angular displacement sensors 10x and 10y have the same configuration,
The configuration of the angular displacement sensor 10x will be described below. FIG. 3 is a sectional view of the angular displacement sensor 10x viewed in the X-axis direction. The block 11 having the shaft hole 11a through which the X-axis shaft 5 penetrates without contact is provided with optical paths 11b and 11c having circular cross sections which are orthogonal to the shaft hole 11a. In the optical paths 11b and 11c, semiconductor light emitting devices 12 and 13 are provided at one end, and a semiconductor light receiving device 14 is provided at the other end.
15 is provided, and the first light beam La and the second light beam Lb from the semiconductor light emitting devices 12 and 13 are made into substantially parallel beams by the collimator lenses 12a and 13a integrally attached thereto, A semiconductor light receiving element which is arranged to face each other through a region of a predetermined cutout 5a provided on the X-axis shaft 5.
The light enters the lenses 14 and 15 through the collimator lenses 14a and 15a. The first and second light beams
La and Lb are orthogonal to each other in the region of the cutout 5a. The notch 5a of the X-axis shaft 5 forms a plane passing through the central axis of the X-axis shaft 5, and its cross section is
It has a semi-circular shape. Therefore, the notch 5a is the fourth
In the figure, the angle with respect to the second light beam Lb is θ, and θ =
When 0 °, the minimum optical path cross-sectional area is given to the first light beam La and the maximum optical path cross-sectional area is given to the second light beam Lb, and when θ = 90 °, It gives a maximum optical path cross-sectional area for the light beam La and a minimum optical path cross-sectional area for the second light beam Lb. In addition, semiconductor light emitting device
12, 13 and the semiconductor light receiving elements 14, 15 are attached so as to be adjustable in a direction perpendicular to their optical axes, respectively, so that an optimum light irradiation state can be obtained. Also, X
The diameter of each light beam is preferably selected to be 0.5 to 1 times the diameter of the X-axis shaft 5 so that the light beam can be effectively shielded partially by the notch 5a of the shaft 5.

Operation of Embodiment Here, first, the operating principle of the above-described angular displacement sensors 10x and 10y will be described.

Since the optical paths 11b and 11c have a circular cross section, the optical path cross sectional areas P and Q for the first and second light beams La and Lb given by the cutout 5a of the X-axis shaft 5 are shown in FIG. It is the area of the dot portion, and if the radius of the optical paths 11b and 11c is d, then P = d ² θ−d ² (sin2θ) / 2 Q = πd ² / 2−d ² θ−d ² (sin2θ) / 2 next, the maximum optical path cross-sectional area because it is πd ^2/2, P, Q
The If the normalized value divided by [pi] d ^2/2 p, respectively, and q, a p = 2θ / π- (sin2θ) / π q = 1-2θ / π- (sin2θ) / π. Therefore, when these differences r = p−q are calculated, r = 4θ / π−1 is obtained. The graphs of p, q, and r obtained above are shown in FIG. 5, where r is a linear function of θ,
It becomes a perfect straight line.

Therefore, when the semiconductor light emitting elements 12 and 13 and the semiconductor light receiving elements 14 and 15 are connected as shown in FIG. 6, the equivalent circuit of the light receiving portion becomes approximately as shown in FIG.
The currents I ₁ and I ₂ of the semiconductor light receiving elements 14 and 15 are approximately I ₁ = k · p I ₂ = k · q (however, due to the incident light amount proportional to the optical path cross-sectional area). k is a constant), its output voltage Vx is given by Vx = R (I ₁ −I ₂ ) = R · k (p−q) using the resistance R on the output side, and Vx = R · k (4θ / π−1). Therefore, the DC voltage Vx proportional to the rotational displacement of the cutout 5a of the X-axis shaft 5 is directly obtained without using any additional circuit.

Now, when the normal detector 1 is brought close to the surface S to be measured of the magnetic body as shown in FIG. 2, the pointer 3a attached to the tip of the measuring rod 2 comes into contact with the surface S to be measured. It is detected by the contact sensor 3b and it is confirmed that the magnet 3 is at an appropriate distance D to the surface S to be measured for generating a sufficient attractive force for measurement. In this state, the attraction force of the magnet 3 attached to the lower end of the measurement rod 2 causes the measurement rod 2 to be rotationally displaced around the X axis with respect to the inner support frame 6, and the inner support frame 6 is moved to the outer support frame 8 Since it is rotationally displaced about the Y-axis, the measuring rod 2 is perpendicular to the surface S to be measured. The central axis of the measuring rod 2 at this time coincides with the normal line to the surface S to be measured. In this case, the measuring rod 2 has X at its center of gravity.
Since it is rotatably supported around the axis and Y axis,
Since it has substantially no inertial rotation moment, it is very light, that is, it can be rotationally displaced in any direction without substantially requiring torque, and has extremely good responsiveness.
The error is small. Then, the rotational displacement of the measuring rod 2 at this time is output voltage from the angular displacement sensors 10x and 10y with respect to the X-axis and the Y-axis, for example, by an arithmetic device (not shown).
Based on Vx and Vy, it is uniquely calculated by a calibration value measured in advance. Thus, the normal direction of the surface S to be measured can be obtained very easily.

The pointer 3a and the contact sensor 3b may be fixed to the lower surface of the magnet 3 on the center line of the measuring rod 2 as illustrated in FIG.

EFFECTS OF THE INVENTION As described above, according to the present invention, a measuring rod having a magnet attached to one end and a counterbalance attached to the other end, and a Y-axis which is orthogonal to the central axis of the measuring rod and the center of gravity of the measuring rod are freely rotatable. The inner support frame that supports the measuring rod and has a common center of gravity with the measuring rod, and the inner support frame that is rotatable about a Y axis that is orthogonal to the X axis and that passes through the center of gravity of the measuring rod. And an outer support frame that is fixedly supported, an angular displacement sensor for the X axis that measures the rotational displacement of the measuring rod with respect to the inner support frame with respect to the X axis, and a Y axis of the inner support frame with respect to the outer support frame. Equipped with an angular displacement sensor for the Y-axis that measures rotational displacement, by which the measuring rod is supported by a gimbal mechanism with two degrees of freedom, and the magnet of the measuring rod approaches the measured surface of the magnetic body Magnetic attraction When a force is applied, the displacement of the measuring rod rotating about the X-axis and the Y-axis with respect to the outer supporting frame is measured by the both angular displacement sensors to detect the normal to the surface to be measured. I am trying to do it. Therefore, the measuring rod having a magnet for measurement is supported by a so-called gimbal mechanism so as to be rotatable about two axes orthogonal to each other around its heavy point, and the operating torque for its operation is extremely small. Therefore, the response is good,
Moreover, it is possible to provide a normal detector with less measurement error.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a normal detector according to the present invention,
2 is a cross-sectional view of the normal detector of FIG. 1 when used in the X axis direction of FIG. 1, and FIG. 3 is an axis of an angular displacement sensor used in the normal detector of FIG. Sectional view as seen in direction 4,
The figure is a partially enlarged view showing the mutual relationship between the light beam and the notch,
FIG. 5 is a graph showing the relationship between the displacement angle of the notch and the optical path cross-sectional area, and FIG. 6 is an electric circuit diagram of the angular displacement sensor.
FIG. 8 is an equivalent circuit diagram of FIG. 6, and FIG. 8 is a side view of another embodiment of the sensor portion. 1 ... Normal detector, 2 ... Measuring rod, 3 ... Magnet,
4 …… Counter balance, 5 …… X axis shaft, 6 ……
Inner support frame, 7 ... Y-axis shaft, 8 ... Outer support frame,
9 ... Support arm, 10x, 10y ... Angular displacement sensor, 11
…… Block, 12, 13 …… Semiconductor light emitting device, 14,15 ……
Semiconductor light receiving element.

Claims (4)

[Claims] 1. A measuring rod having a magnet attached to one end and a counterbalance attached to the other end, and the measuring rod rotatably supported around an X axis orthogonal to the center of gravity of the central axis of the measuring rod. The inner support frame having a common center of gravity with the measuring rod, and the inner support frame rotatably around a Y axis that is orthogonal to the X axis and passes through the center of gravity of the measuring rod.
And an outer support frame that is fixedly supported, an angular displacement sensor that measures the rotational displacement of the measuring rod with respect to the inner support frame about the X axis, and an angle that measures the rotational displacement of the inner support frame with respect to the outer support frame about the Y axis. It is equipped with a displacement sensor, which supports the measuring rod with a gimbal mechanism having two degrees of freedom, and when the magnet of the measuring rod approaches the surface to be measured of the magnetic body and an attractive force acts on this magnet, Normal detection of the measurement rod by detecting the displacement amount of the measurement rod rotationally displaced about the X-axis and the Y-axis with respect to the outer support frame by the angular displacement sensors. vessel. 2. A contact or non-contact sensor for detecting when a tip of a magnet attached to the measuring rod is provided with a tip and the tip of the pointer comes into contact with a surface to be measured or when it reaches a predetermined distance. The normal detector according to claim 1, wherein is provided on the measuring rod. 3. As a contact or non-contact sensor, an object utilizing electrostatic capacitance, an electrically conductive member such as conductive rubber, or a member having contact pressure detection performance is used. The normal detector according to the second paragraph of the above. 4. A pointer of a conductive material is provided at the tip of a magnet attached to the measuring rod, and a relatively low voltage is applied between the measured surface of the magnetic body and the measuring rod. The normal detector according to claim 1, wherein when the tip comes into contact with the surface to be measured, a conduction current generated between the surface to be measured and the measuring rod is measured to output a signal. .