TW201524089A - Linear-rotary actuator and control method thereof - Google Patents

Abstract

The linear-rotary actuator includes: a shaft rod, a magnet row for linear movement that contains a plurality of magnets which are tilted from an end face to a face perpendicular to the axis of the shaft rod and arranged along the shaft rod, and a driving coil for linear movement arranged at the outer circumference of the magnet row for linear movement. Furthermore, the actuator includes: a rotary motor which rotates the shaft rod, and a sensor which is arranged along the magnet row for linear movement and includes a plurality of magnetic components arranged along the axis of the shaft rod. Based on the signals of the sensor, the linear movement location of the shaft rod or a rotation angle of the shaft rod is derived, so as to control the driving coil and the rotary motor. The linear movement location and the rotation angle of the shaft can be detected by the sensor.

Description

Linear-rotary actuator and control method thereof

The present invention relates to a linear-rotary actuator and a control method thereof that are freely linearly movable and rotatable.

Patent Document 1 (Japanese Patent Laid-Open No. 2004-364348) discloses an actuator that is freely linearly movable and rotatable. In Patent Document 1, a linear motor is provided in a shaft of a rotary motor, and the linear motor is rotated as a whole by rotation of the rotary motor, and the output shaft is advanced and retracted by a linear motor. The actuator can be used for applications that must be linearly moved and rotated, such as the drive of a robotic arm.

Patent Document 2 (Japanese Patent No. 3,862,033) discloses a sensor using an interaction of a magnetic body and a coil. In Patent Document 2, for example, a sensor in which an exciting coil and a detecting coil are alternately arranged is opposed to a permanent magnet array. When an alternating current of frequency ω is applied to the exciting coil, an induced voltage of the frequency ω is also generated in the detecting coil. Here, since the intensity of the induced voltage is modulated by the magnetic field from the magnet, the position based on the magnet array can be detected. Further, various types of such position sensors are known, and for example, an exciting coil and a detecting coil can be used in combination. Further, it is known that in order to accurately extract the strength of the modulation, the phase based on the magnet column is set to , extract sin Cosωt signal and cos The signal of sinωt and set to sin by the addition theorem +ωt) and other clever circuits.

[Patent Document 1] Japanese Patent Laid-Open No. 2004-364348

[Patent Document 2] Japanese Patent 3,862,033

In the linear-rotary actuator of Patent Document 1, the encoder and the linear motion position and the rotation angle sensor are required in the rotary motor and the linear motor, respectively, and it is difficult to design in a compact manner. Accordingly, an object of the present invention is to provide a linear-rotary actuator equipped with a sensor capable of measuring both linear motion and rotation.

The present invention is a linear-rotary actuator that is freely linearly movable and rotatable, and is characterized by comprising: a shaft; a linear motion magnet array including a plurality of magnets, the plurality of magnets being self-contained by end faces The axis of the shaft is inclined at a right angle and arranged along the shaft; the linear motion drive coil is disposed on the outer circumference side of the linear motion magnet array; and the rotary motor rotates the shaft; a sensor disposed along the linear motion magnet array; and a control circuit that determines a linear motion position of the shaft or a rotation angle of the shaft according to the signal of the sensor, and controls the driving coil And the above-mentioned rotating motor; and the sensor comprises a plurality of magnetic elements arranged along the axial direction of the shaft.

Furthermore, the present invention is a control method of a linear-rotary actuator that is freely linearly movable and rotatable, the linear-rotary actuator comprising: a shaft; a linear motion magnet array including a plurality of magnets, The plurality of magnets are terminated by a surface that is inclined at a right angle to the axis of the shaft and arranged along the shaft; a linear motion drive coil disposed on an outer peripheral side of the linear motion magnet array; and a rotary motor that causes the shaft a shaft rotation of the rod; and a sensor disposed along the linear motion magnet array and including a plurality of magnetic elements arranged along the axial direction of the shaft, and the magnetic column and the magnetic element by linear motion The interaction causes the signal to change; and regardless of the linear motion and rotation of the shaft, the magnetic field received by the sensor from the column of linear motion changes, and the signal from the sensor The drive coil and the rotary motor are controlled by the control circuit to determine the linear movement position of the shaft or the rotation angle of the shaft from the signal.

In the present invention, a sensor is used which is arranged along a linear motion magnet array and includes a plurality of magnetic elements arranged along the axial direction of the shaft, and is arranged by a linear motion magnet array and a magnetic element. Interaction, and the signal changes. Moreover, with the sensor, the linear motion position and the rotation angle of the actuator can be detected. The signal of the sensor changes according to both linear motion and rotation, and linear motion and rotation can be performed individually by shifting the time, or a plurality of sensors or the like can be provided, thereby separating the signal into linear motion and rotation. Moreover, since linear motion and rotation can be detected by one type of sensor, a miniaturized linear-rotary actuator can be obtained. Further, the shaft can be set to the movable side, and the drive coil can be set to the movable side. In the present specification, the description relating to the linear-rotary actuator can also be directly applied to the control method thereof.

Preferably, the rotary motor includes a rotation magnet array including a plurality of magnets disposed along the shaft, and a rotation drive coil disposed on an outer circumferential side of the rotation magnet array. In this way, the shaft can be used as the axis It is a linear motion motor and a rotary motor, and the shaft is the shared shaft. Therefore, a miniaturized linear-rotary actuator can be obtained.

Preferably, the control circuit is configured to convert the signal of the sensor into a linear motion position when the linear motion drive coil is driven, and convert the signal of the sensor when the rotation motor is driven. Is the angle of rotation. In this way, by linearly moving and rotating individually, the linear motion and rotation of the actuator can be controlled even if the sensor that outputs the signal of linear motion and rotation is output.

Preferably, the sensor is disposed in a plurality of directions along the outer circumference of the shaft, and the control circuit includes the following: determining a linear motion position according to a sum of the plurality of sensor signals, and according to the plurality of senses The rotation angle is obtained by the difference between the detector signals. In this way, linear motion and rotation of the linear-rotary actuator can be performed simultaneously. It is not limited to the added value, and the linear motion can be controlled by the average value or the like, and is not limited to the difference, and the rotation can be controlled by using a constant multiple of the difference or the like.

Preferably, the sensor is disposed on the outer peripheral side of the linear motion drive coil via a magnetic shield including a non-magnetic conductor. By using a magnetic screen to block the alternating magnetic field from the linear motion drive coil, the accuracy of the sensor can be improved, and by arranging the sensor on the outer circumference side of the linear motion drive coil, the linear motion magnet can be shortened. Column.

The linear-rotary actuator is used arbitrarily. If it is an actuator of a wafer mounting machine, it can be characterized in that the rotation of the wafer can be accurately controlled by an actuator having a small output torque and miniaturization. And linear motion.

2, 40‧‧‧ linear-rotary actuator

4‧‧‧ shaft

6, 8‧‧‧ permanent magnets

6a, 6b‧‧‧ magnet

7, 9‧‧‧ magnet column

10,12‧‧‧ drive coil

14, 42, 44‧‧‧ sensors

16‧‧‧ Magnetic screen

18‧‧‧Control circuit

20‧‧‧ hands

22‧‧‧ switch

23, 24‧‧ Query Form (LUT)

25, 26‧‧‧ memory

27, 28‧‧‧ drive circuit

50‧‧‧Control circuit

51‧‧‧Addition Department

52‧‧‧Differentiation Department

53, 54‧‧‧ lookup table (LUT)

L1‧‧‧X-axis travel of the shaft

L2‧‧‧ length

X‧‧‧linear motion position

Θ‧‧‧rotation angle

Px, Pθ, S1, S2‧‧‧ signals

Figure 1 is a diagram showing the main part of the linear-rotary actuator of the embodiment. Figure.

Figure 2 is a cross-sectional view taken along line II-II of Figure 1.

Figure 3 is a cross-sectional view taken along the line III-III of Figure 1.

Fig. 4 is an enlarged view of a main portion of Fig. 1.

Figure 5 is a block diagram of a processing circuit for a sensor signal.

Fig. 6 is a view showing a main part of a linear-rotary actuator of a modification.

Fig. 7 is a block diagram showing a processing circuit of a sensor signal of a modification.

The preferred embodiments for carrying out the invention are shown below. The scope of the present invention should be determined in accordance with the description of the scope of the claims, the description of the invention and the <RTIgt;

1 to 7 show an embodiment and a modification thereof. In the respective drawings, the same reference numerals are given to the same elements, and the meaning of each term is broadly explained with reference to the known art. Fig. 1 shows an embodiment of a linear-rotary actuator 2, in which the element symbol 4 is a shaft such as a cylindrical shape or a cylindrical shape, and the permanent magnets 6 are arranged along the axial direction thereof to constitute a linear motion magnet array 7.

The magnet 6 is, for example, a bonded magnet obtained by molding a magnetic metal powder, has a tubular shape, is fixed to the shaft 4 through a shaft 4 penetrating the center thereof, and both end faces are inclined from a plane at right angles to the axis of the shaft 4. The permanent magnet 6 is magnetized along the axial direction of the shaft 4, and is, for example, arranged such that the S poles face each other or the N poles face each other, and become the magnet array 7. Further, the direction of magnetization (the direction of the magnetic flux in the magnet) and the method of constructing the magnet array 7 are arbitrary.

A plurality of permanent magnets 8 are fixed in an annular shape at one end of the shaft 4, The magnet row 9 for rotation is formed. The magnet 8 is magnetized in the circumferential direction of the shaft 4, and includes, for example, a bonded magnet, and is arranged, for example, such that the S poles face each other or the N poles face each other. Preferably, the permanent magnet 8 has a length L2 equal to or longer than the stroke L1 of the shaft 4 in the axial direction of the shaft 4, and functions as a rotating magnet array even if the shaft 4 moves linearly. .

The component symbol 10 is a linear motion drive coil which is cylindrical and arranged so as to surround the linear motion magnet array 7. The component symbol 12 is a rotation drive coil and has a cylindrical shape and is disposed to surround the rotation magnet array 9. The drive coils 10 and 12 operate, for example, in a U-phase, a V-phase, and a W-phase three-phase drive current, but the types, waveforms, and the like of the drive current are arbitrary. Further, the current flowing to the drive coils 10 and 12 is feedback-controlled based on the linear motion position x and the rotation angle θ of the shaft obtained by the sensor 14. Here, the linear motion magnet array 7 generates a force in the ±x direction of FIG. 1 by interaction with the linear motion drive coil 10. Further, the rotating magnet array 9 is caused to interact with the rotation drive coil 12 to generate a force in the ±θ direction of Fig. 1 . The position in the x direction of FIG. 1 is set as the linear motion position, and the position in the θ direction is set as the rotation angle. In the embodiment, although the shaft 4 and the magnet arrays 7 and 9 are movable sides and the other members are fixed sides, the shaft 4 and the magnet arrays 7 and 9 may be fixed to drive the coils 10 and 12 and other members. Perform linear motion and rotation.

The component symbol 14 is a sensor, and a plurality of magnetic components are arranged along the axial direction of the shaft 4 and are disposed at positions opposed to the magnet array 7. The sensor 14 is, for example, an excitation coil and a detection coil described in Patent Document 2 (Japanese Patent No. 3862033). However, an excitation coil and a detection coil may be used in combination, and other magnetic properties such as a Hall element and a magnetoresistive element may be used. element. Furthermore, a magnetic element refers to an element whose characteristics vary depending on a magnetic field from the outside. Component symbol 16 is a magnetic screen containing non-magnetic metal The interception of the alternating magnetic field from the drive coil. Although the magnetic shield 16 is provided because the sensor 14 is disposed on the outer peripheral side of the drive coil 10, the magnetic shield 16 may not be provided, and the sensor 14 may be disposed at the position of the chain line of FIG.

The component symbol 18 is a control circuit that controls the drive coils 10, 12 by setting the linear motion position x and the rotation angle θ of the shaft according to the signal of the sensor 14. The linear-rotary actuator 2 is used, for example, as a wafer mounting machine. For example, a hand 20 is provided at the front end of the shaft 4, a wafer (not shown) is sucked, and the orientation of the wafer is adjusted by a rotational motion, and the movement in the x direction is used. The wafer is lowered, for example, and mounted on a substrate (not shown). In addition to this, the linear-rotary actuator 2 can also be used for any purpose such as a robot arm, an inspection device, a coating device, and the like.

A cross section of the magnet array 7 at right angles to the axis of the shaft 4 is shown in Fig. 2. Since the end face of the magnet 6 is not at right angles to the shaft, the boundary between the two magnets 6a and 6b can be seen. The drive coil 10 is annular, and a sensor 14 surrounded by the magnetic shield 16 is present on the outer circumference thereof.

A cross section of the magnet array 9 at right angles to the axis of the shaft 4 is shown in Fig. 3. For example, the U-phase, V-phase, and W-phase three-phase drive coils 12 surround the outer circumference of the magnet array 9 in a ring shape, and the shaft 4 is rotated as a rotary motor.

4 shows an enlarged view of the shaft 4 and the drive coil 10, and the shaft 4 penetrates the central axis of the permanent magnet 6, and the end faces of the permanent magnets 6 are inclined with respect to a plane at right angles to the axis of the shaft 4. Further, the permanent magnet 6 is fixed to the shaft 4.

FIG. 5 shows the control circuit 18. The signal of the sensor 14 depends on both the linear motion position x and the rotation angle θ, and the signal is input to the switch 22. In the linear motion of the actuator 2, the signal Px is input to the switch 22, and the sensor signal is converted into a linear motion position by using a look up table (LUT) 23, and The linear motion position x is stored in the memory 25. The linear motion drive circuit 27 controls the drive coil 10 based on the position x. Further, during the rotation of the actuator, the signal Pθ is input to the switch 22, and the sensor signal is converted into a rotation angle by the look-up table 24, and stored in the memory 26 as the rotation angle θ. The rotation drive circuit 28 controls the drive coil 12 based on the rotation angle θ. In the linear motion, for example, the rotation angle θ is fixed and processed, and the linear motion position x is fixed and processed during the rotation, for example, but the processing is not limited thereto.

6 and 7 show a linear-rotary actuator 40 according to a modification, and the same reference numerals as in the embodiment of Figs. 1 to 5 denote the same elements. A plurality of, for example, two sensors 42 and 44 are disposed along the magnet array 7. The sensors 42 and 44 are arranged with a plurality of magnetic elements in the axial direction of the shaft 4, and the signal of one sensor is set to S1. Set the signal of the other sensor to S2. The signals S1, S2 of the two sensors 42, 44 are converted into a linear motion position x and a rotation angle θ by the control circuit 50 of FIG. In order to find the linear motion position x, the sensor signals S1 and S2 are added by the addition unit 51, and converted into a linear motion position x by the look-up table 27. In order to obtain the rotational position θ, the difference between the sensor signals S1 and S2 is obtained by the difference unit 52, and is converted into the rotational angle θ by the look-up table 28. When three or more sensors are provided, the linear motion position x is obtained from the average of the signals, and the rotation angle θ is obtained from the relative values of the signals.

In the embodiment, although the conversion of the sensor signal to the coordinates (position and rotation angle) is performed using the look-up table, the coordinates may be obtained by multiplication or other operations. Further, the rotation drive coil 12 may be disposed around the linear motion magnet array 7, and the shaft 4 may be rotated. In this case, the linear motion magnet array is also used as a rotating magnet array. Further, the sensor 14 may be attached separately from the other members of the linear actuator 2, and the linear actuator 2 may be rotated by a rotating motor (not shown). The detector 14 detects its rotation angle. However, if it is such a design, it will not become a miniaturized linear actuator. Further, when the shaft 4 is supported by an air bearing (not shown), the shaft 4 can be supported in a non-contact manner, and problems such as wear and failure can be reduced.

The embodiment has the following features.

1) The linear motion position and the rotation angle of the linear actuator 2 can be obtained by the sensor 14. In addition, if the rotary actuator or the like is provided in the linear actuator 2, since the shaft 4 moves linearly, an encoder having a length of the stroke of the shaft or the like is required.

2) Linear movement and rotation can be performed by the shaft 4, the magnet arrays 7, 9 and the drive coils 10 and 12, and the size is reduced.

2‧‧‧Linear-rotary actuator

4‧‧‧ shaft

6‧‧‧ permanent magnet

7‧‧‧ Magnet column

8‧‧‧ permanent magnet

9‧‧‧ Magnet column

10‧‧‧ drive coil

12‧‧‧ drive coil

14‧‧‧Sensor

16‧‧‧ Magnetic screen

18‧‧‧Control circuit

20‧‧‧ hands

L1‧‧‧X-axis travel of the shaft

L2‧‧‧ length

X‧‧‧linear motion position

Θ‧‧‧rotation angle

Claims (7)

A linear-rotary actuator which is freely linearly movable and rotatable, comprising: a shaft; a linear motion magnet array comprising a plurality of magnets, the plurality of magnets being self-contained by end faces The axis of the shaft is inclined at a right angle and arranged along the shaft; the linear motion drive coil is disposed on the outer circumference side of the linear motion magnet array; and the rotary motor rotates the shaft; a sensor disposed along the linear motion magnet array; and a control circuit that determines a linear motion position of the shaft or a rotation angle of the shaft according to the signal of the sensor, and controls the driving coil And the above-mentioned rotating motor; and the sensor comprises a plurality of magnetic elements arranged along the axial direction of the shaft. The linear-rotary actuator according to claim 1, wherein the rotary motor includes: a magnet array for rotation, comprising a plurality of magnets arranged along the shaft; and a drive coil for rotation It is disposed on the outer peripheral side of the above-described rotating magnet array. The linear-rotary actuator of claim 1, wherein the control circuit is configured to convert the signal of the sensor into a linear motion position when driving the linear motion drive coil, when driving In the above rotation of the motor, the signal of the sensor is converted into a rotation angle. The linear-rotary actuator of claim 1, wherein the sensor is disposed in a plurality of directions along the outer circumference of the shaft, The control circuit is configured to obtain a linear motion position based on a sum of a plurality of sensor signals, and obtain a rotation angle based on a difference between the plurality of sensor signals. The linear-rotary actuator of claim 1, wherein the sensor is disposed on an outer peripheral side of the linear motion drive coil via a magnetic shield including a non-magnetic conductor. A linear-rotary actuator as claimed in claim 1 is an actuator of a wafer mounter. A control method of a linear-rotary actuator, which is a linearly-rotatable and rotary linear-rotary actuator control method, the linear-rotary actuator is provided with: a shaft; a linear motion magnet array a plurality of magnets, wherein the plurality of magnets are inclined from an end surface at a right angle to an axis of the shaft and arranged along the shaft; and a linear motion driving coil is disposed in the linear motion a peripheral side of the magnet array; a rotating motor that rotates the shaft of the shaft; and a sensor disposed along the linear motion magnet array and including a plurality of magnetic bodies arranged along the axial direction of the shaft The component, and the signal is changed by the interaction of the linear motion magnet array and the magnetic element; and the sensor linearly moves the magnet column regardless of the linear motion and rotation of the shaft The received magnetic field changes, and the signal is taken out from the sensor, and the driving circuit is used to obtain the linear motion position of the shaft or the rotation angle of the shaft from the signal, thereby controlling the driving. Ring and the rotary motor.