JP5036669B2 - Position detection device for moving parts, 2-DOF actuator - Google Patents

Description

  The present invention relates to a two-degree-of-freedom actuator, and more particularly to a position detection device for a movable part thereof.

  Conventionally, the position detection of the rotation and linear motion actuators has been performed using two types of sensors, a rotation sensor and a linear motion sensor. In such a case, there is a problem that the sensor becomes long in the axial direction. Therefore, in Patent Document 1 below, the sensor magnet is trapezoidal and two sensors (sensors A and B) are arranged at positions facing the magnet, and the sensor positions are arranged at positions shifted by an electrical angle of 90 °. Since sensor A and sensor B generate sine and cosine output values with respect to the rotation direction, respectively, when the output of sensor A decreases, the output is switched to sensor B, so that the rotation direction and the linear motion direction Position detection is performed.

JP 2001-12633 A

  In such a case, when detecting the rotational direction, it is necessary to switch the output when the sensor is opposed to the gap between the magnets. When the sensor rotates at a high speed or the number of poles of the sensor magnet is large, the output is switched. Time is a problem.

  Further, in the case of detecting the linear motion direction, the sensor output varies depending on the rotational position, so the position in the linear motion direction must be calculated using the detection result of the rotational direction.

  The present invention obtains the amplitude and phase from the two sensor outputs without switching the sensor outputs, thereby enabling a simple operation to perform a linear motion corresponding to high-speed rotation and high-speed movement as well as two-way motion including rotation. An object of the present invention is to provide a movable part position detection device capable of sensing and a two-degree-of-freedom actuator sensor using the same.

The present invention includes two movable parts having a surface to be measured for detecting a position and movable in a movable direction, and a portion of the movable part that is fixed at a predetermined position so as to face the surface to be measured and that faces the surface to be measured. A position detection sensor unit that generates an output in accordance with the position detection unit, and a position calculation unit that calculates a position of the movable unit in two movable directions from the output generated by the position detection sensor unit. The surface to be measured is inclined so that the distance from the position detecting sensor portion increases or decreases along the first movable direction of two movable directions, or a surface orthogonal to the first movable direction of the two movable directions And the output of the position detection sensor unit periodically changes at a predetermined distance D along the second movable direction of the two movable directions, and the position detection sensor unit includes the first detection unit. Of the movable part in the same plane perpendicular to the movable direction. It consists of a pair of sensors that are at the same distance from the measurement surface and are separated from each other by D / 4 along the second movable direction, and the position calculator is based on the magnitude of the output from the pair of sensors. The position of the movable part in two movable directions is calculated, and the movable part linearly moves in the X direction and the Y direction orthogonal to each other as the first and second movable directions, extends in the XY direction, and extends in the X direction. And a surface to be measured having a structure in which the output of the position detecting sensor unit periodically changes at a predetermined distance D period along the Y direction. in a position detecting device or the like parts.

  According to the present invention, by obtaining the amplitude and phase from two sensor outputs without switching the sensor outputs, the linear motion corresponding to the high speed movement and the high speed rotation and the rotation of the two directions including the rotation can be obtained by a simple calculation. It is possible to provide a movable part position detecting device capable of sensing and a two-degree-of-freedom actuator sensor using the same. As a result, it is possible to reduce the size and weight of the apparatus and to reduce the power consumption (energy consumption).

Embodiment 1 FIG.
1 is a schematic configuration diagram of a two-degree-of-freedom actuator including a movable part position detecting device according to Embodiment 1 of the present invention. A main body portion housed in a container called a can of a two-degree-of-freedom actuator is composed of a drive unit 1 and a position detection unit 2. In the drive unit 1, a rotor 12 provided with a magnetic pole (for example, a magnet) for generating torque and thrust is attached to the rotary shaft 20, and an electromagnetic wave is placed at a position facing the magnet of the rotor 12 on the container 3 side. A stator 11 made of a coil is attached. The stator 11 and the rotor 12 constitute a stepping motor, for example. In the position detection unit 2 in the upper part of the rotor 12 in the axial direction, a truncated cone (or conical) sensor magnet 21 is provided on the rotary shaft 20 so as to be coaxial with the rotor 12. The sensor magnet 21 has a magnetic structure in which the whole or at least a side surface to be measured is magnetized so that the output of the magnetic sensor changes periodically (such as a sine wave shape) due to magnetism, and is arranged in the axial direction. The cross section along it is substantially trapezoidal.

  Two magnetic sensors 23A and 23B each made of a Hall element or a magnetoresistive element or the like are provided on a sensor substrate 22 provided at a distance from the sensor magnet 21 along the outer periphery of the sensor magnet 21 (a top view of FIG. 3). Reference) is provided. The output signals of the magnetic sensors 23A and 23B are calculated by the position calculation unit 4, and the axial direction and rotational position of the sensor magnet 21 are calculated. The drive command signal generator 5 sends a drive command signal for moving a movable body including the rotary shaft 20, the rotor 12, and the sensor magnet 21 according to the position of the sensor magnet 21 calculated by the position calculator 4. To the stator 11.

  FIG. 2 shows an axial positional relationship between the sensor magnet 21 and the magnetic sensor 23A. FIG. 3 shows the positional relationship between the sensor magnet 21 and the magnetic sensors 23A and 23B in the circumferential direction. As shown in FIG. 2, two magnets are provided on the stator side so as to face the side surface that is the measurement target surface of the sensor magnet 21 within the movable range of the sensor magnet 21 (for example, between positions A to C). Sensors 23 </ b> A (23 </ b> B: see FIG. 3) are fixed to the sensor substrate 22. Further, as shown in FIG. 3, the circumferential positions of the two magnetic sensors 23A and 23B are the same distance from the center of rotation on the same axis (more roughly, from the measured surface of the sensor magnet 21 to each other). When the number of pole pairs of the sensor magnet 21 is Pn (in this example, the number of pole pairs is 1), the sensor magnets 21 are arranged at positions 180 / (2 × Pn) apart in mechanical angle. Further, the axial positions of the two magnetic sensors 23A and 23B are arranged in the same plane orthogonal to the axis.

  Here, the output signal waveforms of the magnetic sensors 23A and 23B at the AA, BB, and CC levels in the axial direction of FIG. 2 are shown in FIGS. 4 and 5, respectively. As shown in these figures, the output values of the magnetic sensors 23A and 23B are different at the positions in the linear motion direction, but the outputs of the magnetic sensors 23A and 23B are the cosine wave and sine wave at the respective level positions in the axial direction. Expressed in relationship. For this reason, the position in the linear motion direction is expressed by the following formula (1) when the output value of the magnetic sensor 23A is A and the output value of the magnetic sensor 23B is B, and the square root of these square sums is taken.

V = √ (A ² + B ² ) (1)

  Here, the value of the sensor amplitude value V shown in the equation (1) shows a constant value regardless of the position in the rotation direction, and the value changes only when the sensor moves in the linear motion direction. As the distance between the magnetic sensors 23A and 23B and the sensor magnet 21 increases as the side surface of the sensor magnet 21 inclines along the linear motion direction (axial direction), the sensor amplitude value V becomes as shown in FIG. Since it decreases monotonously, it can be used as a magnetic sensor in the linear motion direction. 6 is a diagram showing a change in the sensor amplitude value V at the linear motion direction position L also shown in FIG. 2. FIG. 6 shows AA and B- in FIG. 2 from the bottom to the top of the vertical axis L in FIG. B, C-C level.

  The rotation position (rotation direction angle) θ can be expressed by the following formula (2).

  θ = arctan (A / B + 90 + 180a) (2)

  Here, a in Expression (2) is 0 when the output value of the magnetic sensor 23B is a positive value, and is 1 when the output value is a negative value. In this case, as shown in FIG. 7, θ is uniquely determined with respect to the rotational position, so that the rotational position can be accurately grasped.

  FIG. 8 is a diagram illustrating an example of the configuration of the position calculation unit 4 and the drive command signal generation unit 5. As shown in FIG. 8, in the position calculation unit 4, the rotation angle calculation unit 4 a regarding the rotation direction calculates the rotation position (rotation direction angle) θ using Equation (2). The amplitude calculation unit 4b related to the linear motion direction calculates the sensor amplitude value V of the magnetic sensor by the equation (1), and the linear motion direction position calculation unit 4c relates to the sensor amplitude as shown in FIG. A table indicating the relationship between the value V and the linear motion direction position L and a conversion formula are stored in advance in the memory, and the linear motion direction position L is calculated based on this table. The drive command signal generation unit 5 determines the rotation position (rotation direction angle) θ of the sensor magnet 21 obtained from the position calculation unit 4 and the phase of the control current from the linear movement direction position L to the stator 11, and fixes them. The electromagnetic coil of the child 11 is energized based on the phase determined as the drive command signal.

  The sensor magnet 21 constitutes a movable part movable in two movable directions having a surface to be measured for detecting the position, and the magnetic sensors 23A and 23B are placed at predetermined positions so as to face the surface to be measured of the movable part. A position detection sensor unit that generates an output in accordance with a portion of the surface to be measured that is fixed is configured, and the phase calculation unit 4 determines the position of the movable unit in two movable directions from the output generated by the position detection sensor unit. A position calculation unit for calculating each is configured.

  The measurement surface of the movable part has an inclination so that the distance from the position detection sensor part increases or decreases along the first movable direction of the two movable directions, or is orthogonal to the first movable direction of the two movable directions. A surface (see Embodiment 3), and the output of the position detecting sensor unit periodically changes at a predetermined distance D period along the second movable direction of the two movable directions. The position detection sensor unit is formed of a pair of sensors provided at the same distance from the surface to be measured of the movable unit within the same plane orthogonal to the first movable direction and spaced apart by D / 4 along the second movable direction. Become. The position calculation unit calculates the position of the movable unit in the two movable directions based on the magnitude of the output from the pair of sensors.

  In particular, the movable part is fixed around the rotation axis as the rotation axis so as to rotate around the rotation axis as the second movable direction and to move linearly along the axial direction of the rotation axis as the first movable direction. It has a conical or frustoconical shape as the surface to be measured.

The surface to be measured of the movable part has a structure in which the output of the position detecting sensor part for Pn period changes periodically over one rotation of the rotation axis, and the pair of sensors is 180 / (in the circumferential direction of the movable part. 2 × Pn) ° are arranged apart from each other. The position calculator calculates the sensor amplitude V from the output values A and B of the pair of sensors by V = √ (A ² + B ² ), and calculates the linear movement position L of the movable unit from the sensor amplitude V. From the output values A and B of the linear motion direction position calculation unit and the pair of sensors, θ = arctan (A / B + 90 + 180a) (a: 0 when the output value of B is a positive value; 1), a rotation angle calculation unit for obtaining the rotation direction angle θ of the movable unit is included.

  In addition, the sensor magnet 21, the sensor substrate 22, the magnetic sensors 23A and 23B, and the position calculation unit 4 constitute a position detecting device of the movable part, and the rotating shaft 20 to which the sensor magnet 21 is attached constitutes a movable body. The rotor 12 and the stator 11 constitute a drive unit that moves the movable body, and the drive command signal generation unit 5 drives the movable body according to the position of the movable unit calculated by the position calculation unit of the position detection device. Drive command signal generating means for inputting the signal to the drive unit.

Embodiment 2. FIG.
FIG. 9 shows a side view of the sensor magnet 21 according to the second embodiment of the present invention. In this embodiment, considering the distance d between the magnetic sensor 23 (23A, 23B) and the side surface of the sensor magnet 21 at each level in the axial direction, as shown in FIG. An envelope along the axial direction (first movable direction) of the side surface that is the measurement surface is a straight line connecting the upper and lower sides of the side surface of the sensor magnet 21 (the broken line in FIG. 9 as in the first embodiment). The shape is such that it is radially inward from the shape shown in FIG. That is, the side surface of the truncated cone-shaped or conical sensor magnet 21 is a curved surface that is dented radially inward.

  In this case, the sensor amplitude value V and the linear motion direction position L calculated by the magnetic sensors 23A and 23B are more linear and monotonously reduced than the case shown in FIG. 5 as shown in FIG. The sensitivity of the magnetic sensor can be increased. Further, if the sensor magnet 21 has a side surface shape in which the sensor amplitude value V of the magnetic sensors 23A and 23B linearly decreases with respect to the position L in the linear motion direction, the magnetic sensor sensitivity can be made more constant. Direction calculation is simplified.

Embodiment 3 FIG.
FIG. 11 is a schematic configuration diagram of a two-degree-of-freedom actuator including a movable part position detecting device according to Embodiment 3 of the present invention. In FIG. 11, the same or corresponding parts as those of the above-described embodiments are denoted by the same reference numerals, and the description thereof is omitted. In the third embodiment, unlike the first and second embodiments, a cylindrical sensor magnet 21 is used, a sensor substrate 22 is provided on the sensor magnet 21, and the sensor substrate 22 includes a sensor magnet 21. Two magnetic sensors 23A and 23B are arranged so as to face the upper surface facing the axial direction, which is the surface to be measured. Similar to the above-described embodiment, the two magnetic sensors 23A and 23B have the same axial position, and are disposed at positions where the circumferential position is shifted by an electrical angle of 90 °. The sensor magnet 21 is magnetized in the axial direction as in the above embodiment. Even in such a configuration, the linear motion direction position (axial distance) and the circumferential position can be specified from the outputs of the two magnetic sensors 23A and 23B in the same manner as described in the first embodiment. Moreover, although the shape of the magnet was a truncated cone shape or a conical shape in the first and second embodiments, the shape of the magnet may be a columnar shape in the present embodiment, which makes it easy to manufacture a sensor magnet.

  Further, although not shown in the drawings, the sensor substrate 22 is provided not on the upper portion of the sensor magnet 21 but on the lower portion so that the sensor substrate 22 faces the lower surface of the sensor magnet 21 facing the axial direction, which is the surface to be measured. The two magnetic sensors 23A and 23B may be arranged in the same manner, and the same effect is obtained.

  The sensor magnet 21 constitutes a movable part, and the movable part rotates around the rotation axis that becomes the second movable direction and linearly moves along the axial direction of the rotation axis that becomes the first movable direction. The cylinder is fixed with the rotation axis as the rotation axis, and the upper or lower surface perpendicular to the axial direction is the measured surface.

Embodiment 4 FIG.
12 is a partial schematic configuration diagram of a position detection unit 2 of a two-degree-of-freedom actuator including a position detection device for a movable unit according to Embodiment 4 of the present invention. FIG. 13 is a perspective view of the position detection unit 2 of FIG. It is the top view seen from the upper part. In this embodiment, the two-degree-of-freedom actuators in the rotation direction and the axial direction of the rotation shaft in the above-described embodiment are used as an example of the other two degrees of freedom. This is an example when applied to an actuator movable in a direction.

  In the figure, the same or corresponding parts as those in the above embodiments are indicated by the same reference numerals. In this embodiment, the sensor magnet 21 is fixed to a movable body (not shown) that moves in a plane in which the first and second movable directions are the X axis and Y axis that are orthogonal to each other in the XY plane. And Basically, in the same manner as in the above-described embodiment, the magnetic sensor 23A, 23B and the measured surface of the sensor magnet 21 are arranged on the measured surface of the sensor magnet 21 in the X-axis direction, which is the first movable direction. Inclination is provided so that the distance monotonously decreases or increases, and in the Y-axis direction, which is the second movable direction, the output signal intensity of the magnetic sensors 23A and 23B periodically changes, for example, with the predetermined distance D as one cycle. Thus, the N pole and the S pole are magnetized. When the period of the signal intensity is D, the interval along the Y-axis direction of the magnetic sensors 23A and 23B fixed to the sensor substrate 22 is D / 4. In this case, the output signals of the magnetic sensors 23A and 23B have a relationship between a sine wave and a cosine wave, and electrical angle positions in two directions can be detected by the equations (1) and (2) as shown in the first embodiment.

FIG. 14 shows an example of the configuration of the position calculation unit 4 in this embodiment. The amplitude calculation unit 41b calculates the following equation (1) from the output values A and B of the pair of magnetic sensors 23A and 23B.
V = √ (A ² + B ² ) (1)
Thus, the sensor amplitude V is obtained. The X-direction position calculation unit 41c calculates the X-direction position X of the sensor magnet 21 that is a movable part based on the sensor amplitude V based on a previously stored table and conversion formula in the same manner as in the above embodiment. The Y-direction position calculation unit 41a calculates the following equation (3) from the output values A and B of the magnetic sensors 23A and 23B.
Yθ = arctan (A / B + 90 + 180a) (3)
(a: 0 when the output value of B is positive, and 1 when it is negative)
Thus, the Y-direction position Yθ of the sensor magnet 21 is obtained. These obtained X-direction position X and Y-direction position Yθ are sent to the drive command signal generator 5. The drive command signal generator 5 converts, for example, an electromagnetic coil corresponding to the stator 11 in FIG. 1 of the actuator drive unit 1 from the X-direction position X and Y-direction position Yθ of the sensor magnet 21 obtained from the position calculation unit 4. The phase of the control current is determined, and the electromagnetic coil is energized based on the phase determined as the drive command signal.

  Furthermore, it is further preferable to provide a calculation function for storing the origin in the Y-axis direction. In this case, by counting the position and cycle from the origin, an arbitrary position can be grasped and used for position control of the two-degree-of-freedom actuator.

  Specifically, as shown in FIG. 13, for example, as shown in FIG. 13, the sensor magnet 21 periodically changes on the surface to be measured for a plurality of cycles, where the distance D between the N pole and the S pole is one cycle. A structure is provided, and a reference position marker R in the Y-axis direction that can be detected by the magnetic sensors 23A and 23B is formed. 14, the reference position detection unit 41d detects the reference position marker R position from at least one output value of the magnetic sensors 23A and 23B, and the cycle counting unit 41e detects the position of the magnetic sensors 23A and 23B. Based on at least one output value, the reference position marker R position is set as the origin, and the period is counted up and down, and the Y direction position calculation unit 41a determines the Y direction position based on the Y direction position Yθ and the period count value of the period counter 41e. Yθa is obtained.

  The present invention is not limited to the above-described embodiments, and can be used in all two-degree-of-freedom actuators to which the above measurement structure can be applied.

  In the present invention, there is a rotor and a stator iron core facing the rotor, and a magnet for generating torque is arranged in the circumferential direction on the rotor. There is a magnet for the sensor above this magnet, and the magnet shape is trapezoidal when viewed from the axial cross section. Two magnetic sensors are arranged on the stator side facing the sensor magnet. Here, the axial positions of the two magnetic sensors are the same, and the circumferential positions of the magnetic sensors are arranged at an electrical angle of 90 ° (the same as the mechanical angle when the sensor magnet has two poles). By taking the sum of squares and arc tangent of these two magnetic sensor outputs in the control circuit, the axial position and circumferential position of the magnetic sensor are obtained. When the magnet has two poles, the absolute position in the circumferential direction of the sensor can be obtained, and when the number of poles is 2n (n> 1), the relative position of the magnetic sensor can be obtained. Further, by providing an arithmetic function for storing the origin and counting the electrical angular period in the rotation axis direction in advance, the absolute position in the circumferential direction can be obtained even when the number of poles is 2n (n> 1).

  In the present invention, the circumferential position can be obtained without switching the output of the magnetic sensor, the control circuit by switching is eliminated, and the present invention can also be applied during high-speed rotation. Further, since the position in the linear motion direction can be calculated by the sum of squares of the output of the sensor, if the circumferential position is the same, the position is constant, and the linear motion position does not depend on the circumferential rotational position.

It is a schematic block diagram of the 2 degree-of-freedom actuator containing the position detection apparatus of the movable part by Embodiment 1 of this invention. It is a figure which shows the positional relationship of the axial direction of the magnet for sensors of FIG. 1, and a magnetic sensor. It is a figure which shows the positional relationship of the circumferential direction of the magnet for sensors of FIG. 1, and a magnetic sensor. It is a figure which shows the output signal waveform of one magnetic sensor in the AA, BB, CC level of the axial direction of FIG. It is a figure which shows the output signal waveform of the other magnetic sensor in the AA, BB, CC level of the axial direction of FIG. It is a figure which shows the change of the sensor amplitude value V in the linear motion direction position L shown by FIG. It is a figure which shows the relationship of (theta) calculated | required in the position calculating part with respect to the rotation position in this invention. It is a figure which shows an example of a structure of the position calculating part in this invention, and a drive command signal generation part. It is a side view of the magnet for sensors in Embodiment 2 of this invention. It is a figure which shows the relationship between the sensor amplitude value V and the linear motion direction position L in Embodiment 1, 2 of this invention. 2 It is a schematic block diagram of the 2 degree-of-freedom actuator containing the position detection apparatus of the movable part by Embodiment 3 of this invention. It is a partial schematic block diagram of the position detection part of the 2 degree-of-freedom actuator containing the position detection apparatus of the movable part by Embodiment 4 of this invention. It is the top view which looked at the position detection part of FIG. 12 from the upper part which saw through the sensor board | substrate. It is a figure which shows an example of a structure of the position calculating part in Embodiment 4 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Drive part, 2 Position detection part, 3 Container, 4 Phase calculation part, 4a Rotation angle calculation part, 4b Amplitude calculation part, 4c Linear motion direction position calculation part, 5 Drive command signal generation part, 11 Stator, 12 Rotor , 20 Rotating shaft, 21 Sensor magnet, 22 Sensor board, 23A, 23B Magnetic sensor, 41a Y direction position calculation unit, 41b Amplitude calculation unit, 41c X direction position calculation unit, 41d Reference position detection unit, 41e Period counting unit.

Claims (5)

A movable part movable in two movable directions having a surface to be measured for detecting a position;
A position detecting sensor unit which is fixed at a predetermined position so as to face the surface to be measured of the movable part and generates an output according to a portion of the surface to be measured facing;
A position calculation unit for calculating the position of the movable unit in two movable directions from the output generated by the position detection sensor unit;
With
The measurement surface of the movable part has an inclination so that the distance from the position detecting sensor part increases or decreases along the first movable direction of two movable directions, or the first movable direction of the two movable directions and The output of the position detection sensor unit periodically changes at a predetermined distance D period along the second movable direction of the two movable directions,
The position detection sensor units are provided at the same distance from the surface to be measured of the movable unit within the same plane orthogonal to the first movable direction, and separated by D / 4 along the second movable direction. Consisting of a pair of sensors,
The position calculation unit calculates the position of the movable unit in two movable directions based on the magnitude of the output from the pair of sensors,
The movable portion linearly moves in the X and Y directions perpendicular to each other as the first and second movable directions, extends in the XY direction, has an inclination along the X direction, and extends along the Y direction. An apparatus for detecting a position of a movable part, comprising: a surface to be measured having a structure in which an output of the position detection sensor part periodically changes at a predetermined distance D period. The position calculation unit is
Amplitude calculation means for obtaining the sensor amplitude V from the output values A and B of the pair of sensors by the following equation (1);
V = √ (A ² + B ² ) (1)
X-direction position calculation means for calculating the X-direction position of the movable part from the sensor amplitude V;
Y-direction position calculation means for obtaining the Y-direction position Yθ of the movable part from the output values A and B of the pair of sensors by the following formula (3):
Yθ = arctan (A / B + 90 + 180a) (3)
(a: 0 when the output value of B is positive, and 1 when it is negative)
including,
The position detecting device for a movable part according to claim 1 . The measurement surface of the movable unit has a structure in which the output of the position detection sensor unit periodically changes for a plurality of periods, and has a reference position marker in the second movable direction,
The position calculation unit is
Reference position detection means for detecting the reference position marker position from at least one output value of the pair of sensors;
Period counting means for counting up and counting down the period based on the reference position marker position based on the output value of at least one of the pair of sensors;
Further including
The Y-direction position calculation means obtains a Y-direction position Yθa based on the Yθ and the period count value of the period counting means;
The position detecting device for a movable part according to claim 2 . The surface to be measured of the movable part has a magnetic body structure magnetized so that the output of the position detecting sensor part periodically changes due to magnetism,
4. The position detection device for a movable part according to claim 1, wherein the pair of sensors of the position detection sensor part is composed of a magnetic sensor including a Hall element or a magnetoresistive element. 5. The position detecting device of the movable part according to any one of claims 1 to 4 ,
A movable body to which the movable portion is fixed;
A drive unit for moving the movable body;
Drive command signal generating means for inputting a drive command signal for moving the movable body to the drive unit according to the position of the movable unit calculated by the position calculation unit of the position detection device;
A two-degree-of-freedom actuator comprising:

Images