JP5132065B2 - 3-DOF rotation detection device and method - Google Patents

Description

  The present invention relates to a three-degree-of-freedom rotation detection apparatus and method capable of detecting rotation with three degrees of freedom.

2. Description of the Related Art An ultrasonic motor that can be rotated not only in one degree of freedom but also in a direction of multiple degrees of freedom is known (see, for example, Patent Document 1). In order to control such an ultrasonic motor, it is necessary to detect the rotation angle (rotational displacement) of the drive portion. As the rotation detection device, a combination of a plurality of one-degree-of-freedom rotary encoders can be considered. However, when such a detection device is used, the rotation of the drive part cannot be detected in a non-contact manner, and an ultrasonic wave Restricts the structure and operation of the motor.
As a technology to detect the rotation angle of the drive part (rotor) of the ultrasonic motor in a non-contact manner, the rotor of the ultrasonic motor is a spherical magnet, and the magnetic field of this spherical magnet is detected by multiple Hall elements to detect the rotation of the rotor. Is disclosed (see Patent Document 2).
As a technique for detecting the rotation angle of a sphere without being limited to an ultrasonic motor, a magnet is embedded in a sphere rotatably accommodated in a case, and the magnetic field of the magnet is detected by a Hall element provided in the case. Thus, there is known one that detects a rotation angle of a sphere in a multi-axis direction without contact (see Patent Document 3).
JP-A-6-210585 JP 2003-70272 A JP 2003-307404 A

By the way, in the technique disclosed in Patent Document 2, since the magnetic field of the spherical magnet is axisymmetric, rotation around the symmetry axis cannot be detected. That is, a case where the rotation with three degrees of freedom cannot be uniquely specified occurs. Moreover, since it is necessary to use a spherical magnet for the rotor, the degree of freedom in designing the rotor is small.
In the technique disclosed in Patent Document 3 above, two magnets are provided symmetrically in order to provide two magnets at positions where the spheres form approximately 90 degrees with each other and detect rotation about three axes of the orthogonal coordinate system. Each must be placed in a position. For this reason, there exists a problem that the freedom degree of arrangement | positioning of a Hall element is small. Further, in this technique, it is possible to detect the rotation of the sphere with three degrees of freedom in the movable range of the operation rod for rotating the sphere, but when the sphere rotates more than 360 degrees around each of the three axes, The rotation angle in the direction of three degrees of freedom cannot be uniquely specified.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a three-degree-of-freedom rotation detection apparatus and method that can uniquely specify rotation in the three-degree-of-freedom direction without contact. There is.

The three-degree-of-freedom rotation detection device according to the present invention includes two magnets having substantially the same shape, and is rotatable around three axes orthogonal to each other around the intersection of the three axes. Are arranged symmetrically with respect to one of the three axes, and each of the two magnets has a distance between the one end of each magnet and the other end. Detected to be provided with a magnetic field having an asymmetry with respect to the intersection of the three axes by arranging the magnetic poles of the two magnets to be different in distance from each other and reversing the polarity direction of the magnetic poles of the two magnets. A magnetic field detecting means for detecting the magnetic field at at least three points that are separated from the detected body and are not on the same straight line, and the magnetic field based on the magnetic field detected at least at the three points by the magnetic field detecting means. Detection means It is characterized by having a three-degree-of-freedom rotation determining means for determining a third rotation angle in the optional direction of the detected body against.
A three-degree-of-freedom rotation detection device according to the present invention includes a magnet, a first axis in the vertical direction, and a second axis and a third axis that are orthogonal to the first axis and orthogonal to each other. Around the intersection of the three axes of the first axis, the second axis, and the third axis, and the magnet has a magnetic field symmetry axis of the three axes. The distance from the intersection of the three axes to the north pole of the magnet is not different from the intersection of the axes, and the distance from the intersection of the three axes to the south pole of the magnet is different. Thus, a detected object to which a magnetic field having asymmetry with respect to the intersection of the three axes is provided, and a magnetic field detecting means that detects the magnetic field at least at three points that are separated from the detected object and are not on the same straight line. And at least the three detected magnetic fields by the magnetic field detecting means Zui and is characterized by having a three-degree-of-freedom rotation determining means for determining a third rotation angle in the optional direction of the body to be detected with respect to the magnetic field detector.
The three-degree-of-freedom rotation detection device according to the present invention is a spherical magnet that can rotate around three axes orthogonal to each other around the intersection of the three axes, and is a part of the spherical magnet. Due to the formation of the recess, the detected object to which a magnetic field having asymmetry with respect to the intersection of the three axes is provided, and at least three points separated from the detected object and not on the same straight line. A three-degree-of-freedom rotation determination for determining a rotation angle in a three-degree-of-freedom direction of the detected object relative to the magnetic field detection means based on a magnetic field detection means for detecting a magnetic field and at least the three magnetic fields detected by the magnetic field detection means And means.
According to this configuration, since the magnetic field having asymmetry with respect to the rotation with three degrees of freedom is applied to the detected object, the magnetic field is detected from the state of the magnetic field at at least three points that are not on the same straight line detected by the magnetic field detection means. The rotation angle in the direction of 3 degrees of freedom of the detection object relative to the detection means is uniquely determined, and the rotation angle in the direction of 3 degrees of freedom of the detection object can be measured by the rotation determination means in 3 degrees of freedom.

In the above-described configuration, the three-degree-of-freedom rotation determining unit may employ a configuration having mapping data that associates the rotation angle in the three-degree-of-freedom direction with the detected magnetic field at at least three points.
According to this configuration, since the rotation angle in the three degrees of freedom direction can be uniquely specified from the mapping data without performing complicated calculation processing, the calculation processing of the rotation angle in the three degrees of freedom direction is reduced.

In the above configuration, the magnetic field detection means includes a plurality of magnetoelectric conversion elements, and the three-degree-of-freedom rotation determination means selects three of the plurality of magneto-electric conversion elements having the largest output and operates in the direction of three degrees of freedom. The configuration used to determine the rotation angle can be employed.
According to this configuration, the rotation angle in the three-degree-of-freedom direction is determined using three of the plurality of magnetoelectric transducers having the largest output, so that the rotation angle can be determined with high accuracy.

In the above configuration, the magnetic field detection unit may have a plurality of substrates that hold at least three or more magnetoelectric conversion elements in common, and each of the plurality of substrates is disposed to face the detection target.
According to this configuration, since the rotation angle in the direction of three degrees of freedom can be measured for each substrate, the measurement accuracy of the rotation angle in the direction of freedom is further increased.

In the above configuration, the three-degree-of-freedom rotation determining unit can employ a configuration including a learning unit that learns the relationship between the rotation angle in the three-degree-of-freedom direction and the detected magnetic field at at least three points to form mapping data.
According to this configuration, since the data can be interpolated by learning without measurement, continuous mapping data can be formed.

  In the above configuration, the configuration may be adopted in which the detection target includes a magnet and a support that supports the magnet. In this case, the magnet may be configured to be built in the support, and the magnet may be configured to be provided on the surface of the support.

In the above configuration, a configuration in which the detection target is a rotor of an ultrasonic motor capable of rotation with three degrees of freedom can be employed.
According to this configuration, it is possible to detect the rotation of the rotor of the ultrasonic motor capable of rotation with three degrees of freedom without contact.

3 DOF rotation detecting method according to the present invention, substantially comprises two magnets having the same shape, Ri rotatable der around three mutually orthogonal axes centered on the intersection of the three axes, the two magnets Are arranged symmetrically with respect to one of the three axes, and each of the two magnets has a distance between the one end of each magnet and the other end. A magnetic field having an asymmetry with respect to the intersection of the three axes is obtained by reversing the polarity direction of the magnetic poles of the two magnets on the detection object arranged so that the distance to the one axis is different. And, based on the detection magnetic field at at least three points that are not on the same straight line, which are detected by the magnetoelectric conversion element, arranged at least at three positions in a predetermined positional relationship apart from the detected object, For the magnetoelectric transducer Wherein detecting a third rotation angle in the optional direction of the body to be detected, it is characterized in that.

  According to the present invention, the rotation in the direction of three degrees of freedom of the detected object that rotates three degrees of freedom with respect to the magnetic detection means can be uniquely specified without contact.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.
1 to 5 are diagrams showing an embodiment of a three-degree-of-freedom rotation detection device (hereinafter referred to as a rotation detection device) according to the present invention. FIG. 1 illustrates a basic configuration of the rotation detection device of the present invention. FIG. 2 is a diagram for explaining the magnetic field formed by the magnet provided on the rotating body, FIG. 3 is a functional block diagram showing the configuration of the electrical system of the rotation detecting device, and FIG. FIG. 5 is a diagram illustrating a relationship with an amplifier, and FIG.

  As shown in FIG. 1, the rotation detection device includes a spherical rotary body 10 as a detection target, a sensor substrate 30 as a magnetic detection means on which a plurality of magnetoelectric conversion elements 40A to 40D are mounted.

  Further, as shown in FIG. 3, the electrical system of the rotation detection device includes an amplifier 50A to 50D that amplifies the outputs of the magnetoelectric conversion elements 40A to 40D, and an analog signal from the amplifiers 50A to 50D that converts the analog signals to digital signals, respectively. / D converters 60A to 60D, an arithmetic unit 70 to which detection signals (detection magnetic field information) are input from A / D converters 60A to 60D, a mapping table unit 80 that holds mapping data described later, and the like.

  The rotating body 10 is composed of a support body 11 formed in a spherical shape, two magnets 20A, 20B, and the like. The rotating body 10 is 3 by using a support mechanism (not shown) with the origin of an orthogonal coordinate system including the X axis, Y axis, and Z axis as a rotation center. It is supported so that it can rotate freely. That is, the rotating body 10 is supported so as to be rotatable around the X-axis, Y-axis, and Z-axis.

The support 11 can be formed of various materials in accordance with the application. For example, it may be formed of a nonmagnetic material such as resin or carbon, or may be a magnetic material.
The support 11 may have a cavity for containing the magnets 20A and 20B inside, or may be solid by being integrally formed with the magnets 20A and 20B by insert molding or the like. .

The magnets 20 </ b> A and 20 </ b> B have the same shape (disc shape), and are built in the support body 11 as shown in FIGS. 1 and 2, and rotate with the rotation of the rotating body 10. As shown in FIG. 2, the magnets 20 </ b> A and 20 </ b> B are arranged so as to form a magnetic field having asymmetry with respect to the rotation center of the three-degree-of-freedom rotation of the rotating body 10.
Each of the magnets 20A and 20B has a symmetric magnetic field with respect to the magnetic field symmetry axis 21 as shown in FIG.
As shown in FIG. 2A, the rotating body 10 includes two magnets 20A and 20B that are arranged at symmetrical positions and have substantially the same shape, and the magnets 20A and 20B have the polarity of the magnetic poles. Inverted.
As shown in FIG. 2A, the magnetic field applied to the rotator 10 has asymmetry and is different at all positions in the three-dimensional space. For this reason, if the state of the magnetic field of at least three points (not on the same straight line) in a predetermined positional relationship is known, the positions of the magnets 20A and 20B can be uniquely determined. This is the detection principle of the three-degree-of-freedom rotation of the present invention.

The sensor substrate 30 is supported at a position away from the rotation center of the rotating body 10 by a support mechanism (not shown).
The sensor substrate 30 can be formed of various materials such as resin, metal, ceramics, etc., and has a flat surface for mounting a plurality of magnetoelectric conversion elements.

The magnetoelectric conversion elements 40 </ b> A to 40 </ b> D are formed by, for example, Hall elements, mounted on the flat main surface of the sensor substrate 30, spaced apart from the rotating body 10, and arranged to face the magnetic field formed by the magnets 20 </ b> A and 20 </ b> B. It detects and converts into an electrical signal, and outputs this to amplifier 50A-50D.
As shown in FIG. 4, the magnetoelectric conversion elements 40 </ b> A to 40 </ b> D output bipolar output voltages V <b> 1 and V <b> 2 that change according to the detected magnetic field to the amplifiers 50 </ b> A to 50 </ b> D.

  As shown in FIG. 4, the amplifiers 50 </ b> A to 50 </ b> D amplify the output voltages V <b> 1 and V <b> 2 by a differential amplifier circuit and output an output voltage Vout. The output voltage Vout has a positive or negative value depending on the direction of the magnetic field detected by the magnetoelectric conversion elements 40A to 40D, that is, the magnitude of the voltages V1 and V2.

The arithmetic unit 70 includes hardware such as a processor and a memory, required software, and the like, and signals from the A / D converters 50A to 50D, that is, signals corresponding to the magnetic fields detected by the magnetoelectric conversion elements 40A to 40D. Are input, and based on these signals, rotation angles (rotation angles around the X, Y, and Z axes) RX, RY, and RZ of the spherical body 10 with respect to the sensor substrate 30 are determined. To do. Note that the computing unit 70 can calculate the rotation speed as well as the rotation angle.
Specifically, the computing unit 70 specifies the rotation angles RX, RY, RZ using the mapping data stored in the mapping table unit 80.

The mapping table unit 80 is formed by, for example, a storage device such as a semiconductor memory, and the values of signals corresponding to the magnetic fields detected by the magnetoelectric conversion elements 40A to 40D and the rotation angles RX, RY, RZ as shown in FIG. Holds mapping data to be associated.
The mapping data shown in FIG. 5 is for one posture of the rotating body 10 with respect to the sensor substrate 30, and actually there exists mapping data for all postures at every predetermined rotation angle.

  Next, a mapping data forming method will be described with reference to FIGS. 6 is a perspective view showing an example of the mapping system, FIG. 7 is a functional block diagram showing the configuration of the electrical system of the mapping system and the three-degree-of-freedom rotation detection device, and FIG. 8 is an example of various mapping data formed by the mapping system. FIG.

The mapping system shown in FIGS. 6 and 7 includes a rotation support mechanism that holds the rotating body 10 and the sensor substrate 30 and rotates the rotating body 10 relative to the sensor substrate 30 with three degrees of freedom.
This rotation support mechanism supports a support column 120 erected on an installation surface (not shown), motors 110, 111, 112 for rotating the rotating body 10 around the X axis, Y axis, and Z axis, and the sensor substrate 30. A support arm 121, a connecting arm 122 that connects the output shaft of the Y-axis motor 111 and the X-axis motor 110, and a connecting arm 123 that connects the output shaft of the X-axis motor 110 and the Z-axis motor 112. And a connecting rod 124 for connecting the Z-axis motor 112 and the rotating body 110 to each other.

  Further, as shown in FIG. 7, the mapping system includes drivers 130, 131, and 132 that supply driving current to the motors 110, 111, and 112, and controllers 140, 141, and 141 that output control signals to the drivers 130, 131, and 132. 142 and the like. The motors 110, 111, and 112 include a rotation angle detector (not shown) such as a rotary encoder, and the detected rotation angles CRX around the X, Y, and Z axes detected by the rotation angle detector. , CRY, CRZ are fed back to the computing unit 70 through drivers 130, 131, 132 and controllers 140, 141, 142.

  In this mapping system, when the Z-axis motor 112 is rotated, the connecting rod 124 is rotated around its own axis, and the rotating body 10 is rotated around the Z-axis. When the X-axis motor 110 is rotated, the connecting arm 123 turns to rotate the rotating body 10 around the X-axis. When the Y-axis motor 111 is rotated, the connecting arm 122 turns to rotate the rotating body 10 around the Y axis.

In the mapping system, when the rotating body 10 is rotated by three degrees of freedom, the rotation angles CRX, CRY, and CRZ detected according to the attitude of the rotating body 10 are input to the computing unit 70 and the rotation with respect to the sensor substrate 30 is performed. The outputs of the magnetoelectric conversion elements 40A to 40D that are uniquely determined according to the posture of the body 10 are input through the amplifiers 50A to 50D and the A / D converters 60A to 60D.
Then, in the calculator 80, for example, as shown in FIG. 8, mapping data for associating the detected rotation angles CRX, CRY, CRZ with the outputs of the magnetoelectric transducers 40A to 40D is set at a predetermined angle with respect to each axis of the rotating body 10. It is formed every time (for example, once) and stored in the mapping table unit 80.

When detecting the rotation angle of the rotating body 10, the computing unit 70 specifies the rotation angle corresponding to the output of the magnetoelectric conversion elements 40 </ b> A to 40 </ b> D stored in the mapping table unit 80, thereby rotating the rotating body 10. The angles RX, RY, RZ are output.
Note that it is possible to measure the rotation angle of the rotating body 10 using the mapping table also on the mapping system. Further, after the mapping data is formed by this mapping system, the rotating body 10 and the sensor substrate 30 can be measured. While being incorporated into another object such as a sonic motor, the rotation angle can be measured using mapping data formed on the object. By adopting such a configuration, it is possible to greatly reduce the processing load on the computing unit 70.

FIG. 9 is a perspective view showing another example of the mapping system.
In the mapping system illustrated in FIG. 6, the sensor substrate 30 is fixed and the rotating body 10 is rotated. However, in the mapping system illustrated in FIG. 9, the rotating body 10 is supported by the support arm 121 and the sensor substrate 30 is mounted. It is connected to the output shaft of the motor 112 for the Z axis. That is, in this mapping system, the sensor substrate 30 is rotated by three degrees of freedom with respect to the fixed rotating body 10. Also in this case, mapping data can be formed in the same manner as described above, and the rotation angle of the rotating body 10 relative to the sensor substrate 30 in the direction of three degrees of freedom can be detected.

A description will be given of still another method of forming the mapping data. In the computing unit 70, for example, a learning system such as a neural network is configured, and the outputs of the magnetoelectric conversion elements 40A to 40D and the detected rotation angles CRX, CRY, CRZ Is used to learn the relationship between the outputs of the magnetoelectric transducers 40A to 40D and the rotation angle of the rotating body 10.
And when detecting the rotation angle of the rotary body 10, as shown in FIG. 10, the magnetoelectric conversion element is learned by the learning system 70B which has learned the relationship between the output of the magnetoelectric conversion elements 40A to 40D and the rotation angle of the rotary body 10. The outputs of 40A to 40D are converted into rotation angles RX, RY, RZ around each axis.
In this way, by forming mapping data that associates the relationship between the outputs of the magnetoelectric transducers 40A to 40D and the rotation angle of the rotating body 10 with the learning system 70B, it is possible to interpolate between the data without learning by measurement. Continuous mapping data can be formed.

Next, still another method of forming the mapping table will be described with reference to FIGS.
In this example, as shown in FIG. 11, a large number of magnetoelectric transducers 40 are arranged around the rotating body 10, and these outputs are taken into the calculator 70.
When the rotating body 10 is rotated by three degrees of freedom with respect to each magnetoelectric conversion element 40, the three-output calculation unit 70C configured in the calculator 70 shown in FIG. Three of the largest outputs are selected to form mapping data.

Here, a specific example of mapping data formation processing by the three-output calculation unit 70C will be described with reference to a flowchart shown in FIG.
For the various variables shown in FIG. 12, V is the output voltage of the magnetoelectric transducer, V1, V2, and V3 are the three maximum voltages (V1 is the largest and V2 is 2) among the output voltages of the many magnetoelectric transducers. No., V3 is No. 3), Vm is a voltage holding variable, i is a counter variable, n is the number of magnetoelectric conversion elements, P is the position of the magnetoelectric conversion element 40, and P1, P2, and P3 are obtained as V1, V2, and V3, respectively. Further, the position of the magnetoelectric conversion element 40, Pm, is set as a position holding variable.
First, various variables are initialized (step ST1), then the absolute values of the output voltages V (i) and V3 of each magnetoelectric transducer 40 are compared (step ST2), and V (i) is larger than V3 In step ST3, the absolute values of V (i) and V2 are compared (step ST3). If V (i) is smaller than V3, the counter variable i is incremented (step ST14).

  In step ST3, when the absolute value of V (i) is smaller than the absolute value of V2, V3 and P3 are temporarily stored in Vm and Pm, and V3 and P3 are stored as V (i) and P (i). Update (step ST4). Then, it is determined whether the angle θ formed by the straight line connecting P1 and P2 and the straight line connecting P1 and P3 is zero degrees. When the angle θ is not zero degrees, the process of step ST14 is executed. In the case of zero degrees (P1, P2 , P3 are on the same straight line), Vm and Pm are substituted into V3 and P3 to cancel the update of V3 and P3.

  If the absolute value of V (i) is larger than the absolute value of V2 in step ST3, the absolute values of V (i) and V1 are compared (step ST7), and the absolute value of V (i) is V1. If smaller, V3, P3 and V2, P2 are temporarily stored, and V2 and P2 are updated with V (i) and P (i) (step ST8). Then, it is determined whether the angle θ formed by the straight line connecting P1 and P2 and the straight line connecting P1 and P3 is zero degrees (step ST9). If not, the process of step ST14 is executed. If P1, P2, and P3 are on the same straight line, updating of V3, P3 and V2, P2 is canceled (step ST10).

In step ST7, when the absolute value of V (i) is larger than the absolute value of V1, V3, P3, V2, P2, V1, and P1 are temporarily stored, and V1 and P1 are set to V (i) and Update with P (i) (step ST11). Then, it is determined whether the angle θ formed by the straight line connecting P1 and P2 and the straight line connecting P1 and P3 is zero degrees (step ST12). If not, the process of step ST14 is executed. If P1, P2, and P3 are on the same straight line, updating of V3, P3, V2, P2, and V1, P1 is canceled (step ST13).
By executing the above processing for all the output voltages of the magnetoelectric transducers 40 (step ST15), V1, V2, V3 and P1, P2, P3 can be determined.

Then, as shown in FIG. 13, the three-output computing unit 70C forms a mapping table in which the obtained V1, V2, V3, P1, P2, and P3 are associated with the detected rotation angle, and maps this. Store in the table unit 80.
When the computing unit 70 detects the rotation angle of the rotating body 10, it selects three of the plurality of magnetoelectric transducers 40 having the largest output, and the corresponding rotation angles are shown in FIG. It is determined using such mapping data.
According to this method, the rotation angle of the rotating body 10 can be detected with higher accuracy as the number of the magnetoelectric conversion elements 40 is increased.

Next, a three-degree-of-freedom rotary ultrasonic motor to which the rotation detection device of the present invention is applied will be described with reference to FIGS.
FIG. 14 is a diagram showing a schematic configuration of a three-degree-of-freedom rotary ultrasonic motor to which the rotation detection device of the present invention is applied, and FIG. 15 is a functional block diagram showing a configuration of an electric system of the ultrasonic motor. 14 and 15, the same reference numerals are used for the same components as those in the above-described embodiment.

In this ultrasonic motor, as shown in FIG. 14, the rotor 10 as a rotor is supported by a support mechanism (not shown) so as to be rotatable with respect to the stator 210 with three degrees of freedom.
In addition, a plurality of sensor substrates 30 supported by the support mechanism 250 are arranged around the rotating body 10 at substantially equal intervals. The sensor substrate 30 is mounted with the magnetoelectric conversion elements 40A to 40D as described above.

The stator 210 includes an actuator made up of laminated piezoelectric elements or the like (not shown), and excites two flexural vibrations that are spatially orthogonal to the longitudinal vibrations and applies them to the rotating body 10 (by combining these vibrations as appropriate). The rotating body 10 is rotated around the X, Y, and Z axes by three degrees of freedom.
The actuator provided in the stator 210 is driven by a motor driver 230 shown in FIG.

  The motor controller 240 generates a control command to be given to the motor driver 230 using the rotation angles RX, RY, RZ around each axis of the rotating body 10 fed back from the computing unit 70. Thereby, precise rotational position control and rotational speed control of the ultrasonic motor can be performed. The rotation angles RX, RY, RZ can be detected by the various detection methods described above.

  In the present embodiment, since vibration is directly applied from the stator 210 to the rotating body 10, it is necessary to select a material that is resistant to wear as the forming material of the rotating body 10, but the rotating body 10 has a configuration in which magnets 20 </ b> A and 20 </ b> B are incorporated. Therefore, the material for forming the rotating body 10 can be freely selected.

Next, another method for applying a magnetic field having asymmetry to the rotating body will be described with reference to FIGS.
A rotating body 10A as a detected body shown in FIG. 16 is formed in a spherical shape and includes a single magnet 20C formed in a disk shape at a position separated from the rotation center.
As shown in FIG. 16B, since the magnetic field symmetry axis of the magnet 20C is away from any rotation axis of the rotating body 10A, a magnetic field having asymmetry is applied to the rotating body 10A. . The magnet 20C can be provided on the surface of the rotating body 10A.

A rotating body 10B shown in FIG. 17 includes a magnet 20D formed in a rectangular parallelepiped shape so that its magnetic field symmetry axis coincides with one rotating axis J1 of the rotating body 10B.
Here, as shown in FIG. 17B, the magnetic field of the magnet 20D has symmetry with respect to the rotation axis J1, but has asymmetry with respect to the other two rotation axes. Therefore, the rotation angle around the other two rotation axes can be uniquely determined.
Regarding the rotation around the rotation axis J1, when the magnetic field of the magnet 20D is sampled by the magnetoelectric conversion element, the rotation body 10B rotates around the rotation axis J1 within a range of less than 180 degrees within the sampling time. Then, the rotation angle around the rotation axis J1 of the rotating body 10B with respect to the magnetoelectric conversion element can be uniquely determined. That is, a magnetic field having asymmetry can be applied to the rotating body 10B by using a single magnet 20D formed in a rectangular parallelepiped shape.

  A rotating body 10C shown in FIG. 18 is formed of a spherical magnet (magnetized sphere), and a recess 11 is formed on a part of the surface. In a state where there is no recess 11, the magnetic field of the rotating body 10 </ b> C has rotational symmetry, but by forming the recess 11, it is possible to provide asymmetry. A convex portion may be formed instead of the concave portion 11.

A rotating body 10D shown in FIG. 19 includes a cylindrical magnet 20E disposed therein, and members 12 and 13 formed of materials having mutually different magnetic permeability facing both magnetic poles of the magnet 20E. Has been placed.
By providing the member 12 and the member 13 having different magnetic permeability with respect to both magnetic poles of the magnet 20E, the symmetry of the magnetic field of the magnet 20E is broken, so that a magnetic field having asymmetry can be given to the rotating body 10D.

  A rotating body 10E shown in FIG. 20 is formed of a magnet itself and contains substances 15 and 6 having different magnetic permeability in a non-uniform manner, similarly to the rotating body 10C shown in FIG. Thereby, similarly to the rotating body 10D shown in FIG. 19, a magnetic field having asymmetry can be applied to the rotating body 10D.

  In the above embodiment, the case where the rotating body 10 as the detected body is rotated by 3 degrees of freedom with respect to the sensor substrate 30 on which the magnetoelectric conversion element 40 is mounted has been described, but the present invention is not limited to this. It is also possible to fix the rotating body 10 and rotate the magnetoelectric conversion element 40 (sensor substrate 30) relative to the rotating body 10 to determine the magnetoelectric conversion element 40 with respect to the rotating body 10 by three degrees of freedom.

In the above embodiment, the case where the object to be detected is spherical has been described as an example. However, the present invention is not limited to this, and the shape of the object to be detected can be variously changed.
Moreover, although the case where the several magnetoelectric conversion element 40 was mounted in the sensor board | substrate 30 was demonstrated, it is also possible to install each magnetoelectric conversion element 40 separately.

  In the above-described embodiment, the case where the present invention is applied to detection of rotation of three degrees of freedom of an ultrasonic motor has been described. However, the present invention is not limited to this and can be applied to any object that rotates three degrees of freedom.

  In the above embodiment, the configuration for measuring the rotation angle in the three-degree-of-freedom direction using the mapping data has been described. However, the present invention is not limited to this. From the detection signal of the magnetoelectric conversion element, the arrangement information of the magnetoelectric conversion element, and the like. It is also possible to calculate the rotation angle in the direction of three degrees of freedom.

  Although the case where the magnet was built in the support body was demonstrated in the said embodiment, it is also possible to provide so that a magnet may be exposed to the surface of a support body.

It is a figure for demonstrating the basic composition of the 3 degree-of-freedom rotation detection apparatus of this invention, Comprising: (A) is the perspective view seen from the Y-axis direction of the 3-degree-of-freedom rotation detection apparatus, (B) is a Z-axis direction. There is a perspective seen from. (A) is a figure which shows the magnetic field which the magnet provided in the rotary body forms, (B) is a figure which shows the symmetry of the magnetic field of a magnet. It is a functional block diagram which shows the structure of the electric system of a 3-degree-of-freedom rotation detection apparatus. It is a figure which shows the relationship between a sensor board | substrate and amplifier. It is a figure which shows an example of the mapping data of a mapping table part. It is a perspective view which shows an example of a mapping system. It is a functional block diagram which shows the structure of the electrical system of a mapping system and a 3-degree-of-freedom rotation detection apparatus. It is a figure which shows the example of the various mapping data formed by the mapping system. It is a perspective view which shows the other structure of a mapping system. It is a figure for demonstrating the other formation method of a mapping table. It is a figure for demonstrating the other formation method of a mapping table. It is a flowchart which shows an example of the process in the system shown in FIG. It is a figure which shows the example of the mapping data formed with the system shown in FIG. It is a perspective view which shows the structure of the ultrasonic motor to which this invention was applied. It is a functional block diagram which shows the structure of the electric system of the ultrasonic motor shown in FIG. It is a perspective view which shows the other method of giving an asymmetry to a magnetic field, (A) is a front view, (B) is a side view. It is a perspective view which shows the other method of giving an asymmetry to a magnetic field, Comprising: (A) is a front view, (B) is a top view. It is a figure which shows the further another method of giving an asymmetry to a magnetic field. It is a perspective view which shows the other method of giving asymmetry to a magnetic field. It is a perspective view which shows the other method of giving asymmetry to a magnetic field.

Explanation of symbols

10, 10A to 10E ... Rotating body (detected body)
20, 20A to 20E ... Magnet 30 ... Sensor substrate (magnetic field detecting means)
40: Magnetoelectric conversion element (magnetic field detecting means)
50A-50D ... Amplifiers 60A-60D ... A / D converter 70 ... Calculator (3-degree-of-freedom rotation determining means)
70B ... Learning system (learning means)
80 ... Mapping table 110, 111, 112 ... Motor 120 ... Support pillar 121 ... Support member 122, 123 ... Connection member 124 ... Connection rod 130-132 ... Driver 140-142 ... Controller

Claims (12)

Two magnets having substantially the same shape are provided and are rotatable around three axes orthogonal to each other around the intersection of the three axes, and the two magnets are arranged on one of the three axes. The two magnets are arranged so as to be symmetric with respect to each other, and the distance between one end of each magnet with respect to the one axis and the distance between the other end with respect to the one axis are different from each other. And the detected object to which a magnetic field having asymmetry with respect to the intersection of the three axes is applied by reversing the polarity direction of the magnetic poles of the two magnets,
Magnetic field detection means for detecting the magnetic field at at least three points apart from the detected object and not on the same straight line;
3-degree-of-freedom rotation determining means for determining a rotation angle of the detected body with respect to the magnetic field detecting means in the direction of 3-degree-of-freedom based on at least the three magnetic fields detected by the magnetic field detecting means;
A three-degree-of-freedom rotation detection device comprising: A first axis in the vertical direction, and a second axis and a third axis that are orthogonal to the first axis and orthogonal to each other. The three axes of the second axis and the third axis are rotatable about the intersection of the three axes, and the magnet does not pass through the intersection of the three axes, and the magnetic field symmetry axis of the magnet does not pass through the intersection of the three axes. By arranging the distance from the intersection of the axes to the N pole of the magnet and the distance from the intersection of the three axes to the S pole of the magnet , the asymmetry is obtained with respect to the intersection of the three axes. A detected object to which a magnetic field having
Magnetic field detection means for detecting the magnetic field at at least three points apart from the detected object and not on the same straight line;
3-degree-of-freedom rotation determining means for determining a rotation angle of the detected body with respect to the magnetic field detecting means in the direction of 3-degree-of-freedom based on at least the three magnetic fields detected by the magnetic field detecting means;
A three-degree-of-freedom rotation detection device comprising: A spherical magnet that is rotatable around three axes orthogonal to each other around the intersection of the three axes, and a recess is formed in a part of the spherical magnet, thereby A detected object provided with a magnetic field having asymmetry with respect to the intersection of the axes;
Magnetic field detection means for detecting the magnetic field at at least three points apart from the detected object and not on the same straight line;
3-degree-of-freedom rotation determining means for determining a rotation angle of the detected body with respect to the magnetic field detecting means in the direction of 3-degree-of-freedom based on at least the three magnetic fields detected by the magnetic field detecting means;
A three-degree-of-freedom rotation detection device comprising:   4. The 3 degrees of freedom according to claim 1, wherein the 3 degrees of freedom rotation determining means includes mapping data that associates a rotation angle in a direction of 3 degrees of freedom with a detected magnetic field at least at the three points. 5. Degree rotation detection device. The magnetic field detection means has a plurality of magnetoelectric conversion elements,
The three-degree-of-freedom rotation determining means is used for selecting a rotation angle in the three-degree-of-freedom direction by selecting three of the plurality of magnetoelectric transducers having the largest output. The 3-degree-of-freedom rotation detection device according to any one of 1 to 4. The magnetic field detection means has a plurality of substrates that hold at least three or more magnetoelectric conversion elements in common,
6. The three-degree-of-freedom rotation detection device according to claim 1, wherein the plurality of substrates are respectively arranged to face the detection target.   The three-degree-of-freedom rotation determining means includes learning means for learning the relationship between a rotation angle in the three-degree-of-freedom direction and a detected magnetic field at least at the three points to form the mapping data. The three-degree-of-freedom rotation detection device according to any one of 1 to 6.   The three-degree-of-freedom rotation detection device according to claim 1, wherein the detection target includes a support that supports the magnet.   The three-degree-of-freedom rotation detection device according to claim 8, wherein the magnet is built in the support.   The three-degree-of-freedom rotation detection device according to claim 8, wherein the magnet is provided on a surface of the support.   11. The three-degree-of-freedom rotation detection device according to claim 1, wherein the detected object is a rotor of an ultrasonic motor capable of rotating with three degrees of freedom. Two magnets having substantially the same shape are provided, and are rotatable around three axes orthogonal to each other around the intersection of the three axes, and the two magnets are relative to one of the three axes. The two magnets are arranged such that a distance between one end of each magnet with respect to the one axis and a distance between the other end with respect to the one axis are different from each other. A magnetic field having an asymmetry with respect to the intersection of the three axes is imparted to the detected object by reversing the polarity direction of the magnetic poles of the two magnets;
Arranging magnetoelectric transducers in at least three locations that are in a predetermined positional relationship away from the object to be detected;
The rotation angle in the direction of three degrees of freedom of the detected object relative to the magnetoelectric conversion element is detected based on detected magnetic fields at at least three points that are not on the same straight line that are detected by the magnetoelectric conversion element. Degree of freedom rotation detection method.

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