JP4070869B2 - Servo motor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a servo motor device including a resolver that detects a rotational position.
[0002]
[Prior art]
For example, in order to perform operations and device operations in an environment where radiation is generated from a nuclear power plant or a medical device in a hospital, a robot or manipulator is controlled by remote operation.
[0003]
By the way, a servo motor is used as a drive source for each drive shaft of such a robot or manipulator, and the rotation position of the servo motor is detected, and the detection signal is transmitted to the central controller to perform arithmetic processing necessary for control. And the servo motor is driven based on the calculation result.
[0004]
Conventionally, in order to detect the rotational position of the servo motor, a detector made of a semiconductor cannot be used in a radiation environment, so an encoder system that optically detects the rotational position by providing a light emitting diode or the like on the rotating body can be considered, Such a rotational position detector requires an optical fiber for transmitting an optical signal. However, this optical fiber has a problem that a so-called browning phenomenon occurs, which is discolored when exposed to radiation.
[0005]
In view of this, it has been considered to use an induction type rotational position detector having a configuration in which a rotational transformer is provided on the rotor side, so that the rotational position of the servo motor can be detected without being affected by radiation.
[0006]
[Problems to be solved by the invention]
However, this induction-type rotational position detector has an iron core in the rotary transformer, so it is difficult to reduce the size of the detector. Is impossible.
[0007]
The induction type rotational position detector detects the electrical phase angle using the change in magnetoresistance according to the rotational position as an output signal based on the fact that the gap between the stator and the rotor changes according to the rotational position. is doing. For this reason, when the rotational position of the servo motor is detected by the phase method and two signal waveforms having the same amplitude value are transmitted to the remote central control device, the detected signal is affected by the impedance of the transmission line and the phase shift is caused. At the same time, the waveform is distorted, making it difficult to recognize the waveform to be used as a reference, and there is a problem in terms of detection accuracy.
[0008]
The present invention has been made to solve the above problems, and its purpose is to integrate a resolver that can detect a rotational position with high accuracy by a weak magnetic field using an air-core coil directly to a servo motor. Accordingly, it is an object of the present invention to provide a servo motor device that can be downsized as a whole and is not affected by the use environment.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention constitutes a servo motor device by the following means.
According to a first aspect of the present invention, there is provided a rotary shaft rotatably supported by a bearing, a rotor attached to the rotary shaft, and surrounding the rotor, wherein the bearing is provided at both ends in the axial direction. A servo motor comprising a bracket attached to the bracket, a frame attached to the bracket and a stator attached to the inner peripheral surface of the frame, a disk-like rotor attached to one end of the rotating shaft, and the disk-like rotor Are arranged coaxially so as to face each other, fixed to the bracket, a plurality of outer coils arranged at equal intervals in the circumferential direction on a surface of the stator facing the disc-shaped rotor, and the plurality of outer coils. In order to correspond to each of the above, a disk comprising a plurality of inner coils arranged at equal intervals in the circumferential direction on the surface facing the disk-shaped rotor and having a smaller number of turns than the number of turns of the outer coil. ; And a Luba, the resolver on the basis of the two different output amplitude value from the outer coil and the inner coil, and detects the rotational position of the servo motor.
[0010]
Therefore, in the servo motor device configured as described above, a resolver that can detect the rotational position with high accuracy by a weak magnetic field using an air-core coil is directly connected to the servo motor and integrated. The overall size can be reduced, and the manufacturing cost is reduced.
[0011]
According to a second aspect of the present invention, in the servo motor device according to the first aspect of the present invention, the resolver includes a pair of an outer coil and the inner coil at a position shifted from the outer coil in the circumferential direction. The rotational position of the servo motor is detected based on two outputs having different amplitude values and phases from the outer coil and the inner coil .
[0012]
Therefore, in the servo motor device having the above-described configuration, a resolver that outputs two signal waveforms having different amplitude values and phases according to the rotation position of the servo motor is used. The reference phase can be recognized even if the signal is distorted, and the phase difference can be detected with high accuracy.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a configuration example of an embodiment of a servo motor device according to the present invention. In FIG. 1, reference numeral 1 denotes a small servo motor. The servo motor 1 is a rotary shaft 3 rotatably supported by a pair of bearings 2 provided at an appropriate distance, and a rotor 4 attached to the rotary shaft 3. The frame 6 is provided so as to surround the rotor 4 and is attached to the bracket 5 that supports the bearing 2 at both ends in the axial direction, and the rotor 3 and the minute gap exist on the inner peripheral surface of the frame 6. It is comprised by the stator 7 attached as follows.
[0014]
On the other hand, 10 is a resolver directly connected to one end of the rotating shaft 3 of the servo motor 1. This resolver 10 is a stator 11 in which a plurality of air core coils are arranged, and a rotor provided to face the air core coils of the stator 11. 12, and the rotational position of the servo motor 1 can be detected with a weak magnetic field. In this case, the stator 11 is fixed to the bracket 5 portion of the servo motor 1 by the set screw 14 via the adapter 13, and the shaft portion of the rotor 12 is fixed to the rotating shaft 15 of the resolver 10 by the set screw 16 so as to be integrated. It can be rotated.
[0015]
FIGS. 2A and 2B show the relationship between the arrangement of coils on the stator 11 side of the resolver 10 and the rotor 12. FIG. 2A is a plan view and FIG. 2B is an axial sectional view.
As shown in FIG. 2, a plurality of outer coils 17 having a double winding structure are attached at equal intervals in the circumferential direction of the end face of the stator 11, and the number of turns is increased by the plurality of outer coils 17 on the inner side. The inner coils 18 having a small number are attached at regular intervals.
[0016]
In addition, the rotor 12 is provided with a plurality of slits 19 having an appropriate length in the radial direction at equal intervals in the circumferential direction.
Although not shown, excitation windings for generating magnetic flux interlinking with the inner coil 18 and the outer coil 17 are provided on the stator side.
[0017]
Incidentally, the resolver 10 has a diameter of about 20 mm to 10 mm.
Therefore, in the induction type resolver 10 having such a configuration, when the rotor 12 is rotated integrally by the rotation of the servo motor 1, the outer coil 17 and the inner coil 18 of the stator 11 correspond to the rotational position of the rotor 12. An electromotive force is generated. As shown in FIG. 2 (a), for example, the coil at the A position of the outer coil 17 and the coil at the A 'position of the inner coil 18 shifted in the circumferential direction are combined with the electromotive force. By taking out the output, it is possible to give a 90 ° phase difference in electrical angle. The coils at other positions of the outer coil 17 and the inner coil 18 can be grouped in the same relationship and taken out of the respective outputs, thereby giving the same phase difference.
[0018]
In this case, an output with a large electromotive force, that is, an output with a large peak value, can be extracted from the outer coil 17, and an output with a small electromotive force, that is, a small peak value, can be extracted from the inner coil 18. In addition, since a plurality of radial slits 19 are provided at equal intervals in the rotor 12 so that eddy current does not flow, a large electromotive force can be obtained comprehensively.
[0019]
Next, a system in which the servo motor device having such a configuration is used as a drive source for each drive shaft of a robot and is controlled by a remote central control device will be described with reference to FIG.
[0020]
The resolver 10 detects the rotational position of the servo motor 1 by a phase difference method, and transmits the detection signal to the remote central controller 20. The central controller 20 performs arithmetic processing on the detection signal and gives a control signal necessary for the next operation to the servo motor 1 for control.
[0021]
In this case, the resolver 10 outputs the rotational position of the servo motor 1 as a phase difference signal having a large peak value and a small peak value with a weak magnetic field, so that the phase difference from the reference signal is clear. Thus, long-distance transmission is possible. That is, as shown in FIG. 4A, the two signal waveforms Va having a large peak value and the signal waveform Vb having a small peak value output according to the rotational position of the servo motor 10 detected by the resolver 10 are far apart. When transmitted to the central controller 20, even if the peak value changes with the transmission distance, the relative ratio of the peak values of the two signal waveforms Va ′ and Vb ′ and the phase difference between the two signals do not change. Since the ratio does not change even if the amplitude value of both signals is attenuated depending on the transmission distance, the reference signal waveform can be confirmed.
[0022]
Therefore, the rotational position of the servo motor 10 can be detected with high accuracy from the phase difference between these signals.
On the other hand, the induction type resolver using the conventional rotary transformer outputs two signal waveforms V1 and V2 having the same amplitude value according to the rotational position as shown in FIG. If the waveform distortion increases due to long-distance transmission, it is difficult to confirm the signal waveforms V1 ′ and V2 ′ to be used as a reference.
[0023]
As described above, in the present embodiment, the resolver that can detect the rotational position with a weak magnetic field using the air-core coil with high accuracy is directly connected to the servo motor so as to be integrated. Manufacturing cost is reduced.
[0024]
Further, since a resolver that outputs two signal waveforms having different amplitude values and phases according to the rotational position of the servo motor is used, the phase difference can be detected even if both signals are distorted by long-distance transmission.
[0025]
Incidentally, the transmission distance of about 20 m is the limit in the past, but in this embodiment, transmission of about 40 m is possible.
In the above embodiment, the configuration in which the outer coil and the inner coil having different numbers of turns are arranged as shown in FIG. 2 has been described. However, the rotational position can be detected with high accuracy by a weak magnetic field using an air-core coil. As long as it is a thing, things other than the said structure may be sufficient.
[0026]
【The invention's effect】
As described above, according to the present invention, since the resolver that can detect the rotational position with a weak magnetic field using an air-core coil with high accuracy is directly connected to the servo motor and integrated, the whole can be downsized and used. An inexpensive servo motor device that is not affected by the environment can be provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a configuration example of an embodiment of a servo motor device according to the present invention.
FIGS. 2A and 2B show a relationship between an arrangement example of coils on the stator side of the resolver of the embodiment and a rotor, wherein FIG. 2A is a plan view and FIG. 2B is an axial sectional view;
FIG. 3 is a diagram showing a system configuration example applied when the servo motor device according to the present invention is used as a drive source of each drive shaft of a robot, for example, and is controlled by a remote central control device.
FIG. 4 shows a signal waveform of a phase difference method according to the rotational position of a servo motor detected by a resolver in the same system, as compared with the conventional one, (a) is a signal waveform diagram of the present invention, (b) ) Is a conventional signal waveform diagram.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Small servo motor 2 ... Bearing 3 ... Rotary shaft 4 ... Rotor 5 ... Bracket 6 ... Frame 7 ... Stator 10 ... Resolver 11 ... Stator 12 ... Rotor 13 ... Adapter 14 , 16 ... Set screw 15 ... Rotating shaft 17 ... Outer coil 18 ... Inner coil 19 ... Slit

Claims (2)

A rotating shaft rotatably supported by a bearing, a rotor attached to the rotating shaft, a bracket provided so as to surround the rotor and supporting the bearing at both ends in the axial direction, and attached to the bracket A servo motor comprising a frame and a stator attached to the inner peripheral surface of the frame;
A disk-shaped rotor attached to one end of the rotating shaft, a stator that is coaxially disposed so as to face the disk-shaped rotor, fixed to the bracket, and a surface of the stator that faces the disk-shaped rotor. A plurality of outer coils arranged at equal intervals in the circumferential direction and a plurality of outer coils arranged at equal intervals in the circumferential direction on a surface facing the disk-shaped rotor so as to correspond to each of the plurality of outer coils. A resolver composed of a plurality of inner coils having a smaller number of turns than the number of turns;
Comprising
The resolver detects a rotational position of the servomotor based on two outputs having different amplitude values from an outer coil and an inner coil . The resolver sets an outer coil and the inner coil at a position shifted in the circumferential direction from the outer coil, and sets the servo based on two outputs having different amplitude values and phases from the outer coil and the inner coil. 2. The servo motor device according to claim 1 , wherein the rotational position of the motor is detected .

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