WO2002101914A1

WO2002101914A1 - Servo actuator and position detecting device therefor

Info

Publication number: WO2002101914A1
Application number: PCT/JP2002/005772
Authority: WO
Inventors: Shinji Ishii
Original assignee: Sony Corporation
Priority date: 2001-06-11
Filing date: 2002-06-11
Publication date: 2002-12-19
Also published as: JP2003070284A

Abstract

A rotational position detector is mounted both on the rotational shaft of a rotor (11) and on the output shaft of a speed-reduction gear section (20). If the detected value of the rotational position (θm) of the rotor (11) is 1024 pulses/revolution and the speed-reduction ratio (Gn) is 4, then that of the speed-reduction gear section (20) is 1024 × 4 = 4096 pulses/revolution of the output shaft; thus, the absolute rotational position can be detected with high accuracy. Since the integer portion (N) of θg × Gn/2 π is the number of revolutions the rotor (11) makes when the output shaft has rotated by θg, the absolute rotational position of the rotor (11) can be calculated by θm + N × 2 π. Therefore, the position of the rotational shaft can be detected with high accuracy without being influenced by temperature change.

Description

TECHNICAL FIELD The present invention relates to a multi-axis drive system such as a robot, a general-purpose assembly device, a robot / hand device, and other multi-axis control devices. More particularly, the present invention relates to a servo actuator capable of detecting a posture position of a rotating shaft with high accuracy and a position detecting device therefor.

More specifically, the present invention relates to a servo actuator unit having a drive circuit built in the same module and a position detecting device therefor, and more particularly, to the influence of a temperature change in the module. The present invention relates to a servo actuator for detecting the attitude position of a rotating shaft with high accuracy without receiving the same, and a position detecting device therefor.

[Background Art] Machines that perform movements that resemble human movements using electric or magnetic action are called “robots”. It is said that the root of the robot comes from the Slavic word "ROBOTA" (robot machine). In Japan, robots began to spread in the late 1960s, but most of them were industrial robots such as manipulators and transport robots for the purpose of automation of factory production operations-unmanned operations. It was an industrial robot.

A stationary type robot, such as an arm-type robot, which is planted and used in a specific place, operates only in a fixed / local work space such as assembling and sorting parts. On the other hand, the mobile robot has a work space that is not limited, and can freely move on a predetermined route or on a non-route to perform a predetermined or arbitrary human task, or to perform human or human tasks. A wide variety of services can be provided to replace dogs or other living beings. Among them, the legged mobile robot is a crawler type Posture control and walking control are more difficult and difficult to control than robots of the robot type.However, P It is excellent in that it can be realized.

Recently, a pet-type robot that simulates the body mechanism and movement of a four-legged animal such as a cat, or the body mechanism and movement of an animal that walks two-legged upright, such as a human, has been modeled. Research and development on legged mobile robots, such as the “humanoid” or “humanoid” robots designed in advance, has advanced, and expectations for their practical use are increasing. For example, Sony Corporation announced a humanoid robot "SDR-3X" that can walk on two legs on January 21, 2002.

This type of legged mobile robot generally has a large number of degrees of freedom of joints, and joint movement is realized by an actuator motor. Also, by taking out the rotation position, rotation amount, etc. of each motor and performing servo control, a desired operation pattern is reproduced and attitude control is performed.

In general, servo motors are used to achieve the robot's freedom of joints. This is based on the fact that it is easy to handle, small, has high torque, and has excellent responsiveness. In particular, the AC servos have no brushes and are maintenance-free, so automatic machines that are desired to operate in an unmanned work space, such as legs that can walk freely, are used. It can be applied to robot joints and other events. In the AC servo motor, a permanent magnet is arranged on the rotor (lower) side, and a coil is arranged on the stator (stationary) side. It is designed to generate torque.

Legged mobile robots are generally composed of a large number of joints. Therefore, it is necessary to manufacture a servo 'designing a compact and high-performance motor' that constitutes the degree of freedom of joints. For example, Japanese Unexamined Patent Application Publication No. Hei 12-29664 (Japanese Patent Application No. Hei 11-333886), which has already been assigned to the present applicant, discloses a joint-type mobile robot with a joint actuator. A compact AC servo actuator that is directly connected to a gear and has a single-chip servo control system and is built into a motor unit is disclosed. In a multi-axis drive system such as a legged mobile robot, it is necessary to detect the rotational position of each axis with high accuracy and stability, and to operate accurately by a position command. For example, in a bipedal legged mobile robot such as a humanoid robot, the robot autonomously checks its own posture position immediately after turning on the power to the aircraft and moves each axis to a stable posture position. Need to be moved.

Therefore, in the AC servo factory that gives the degree of freedom of rotation of each joint, a more accurate rotation position detector must be equipped to realize such a stable posture. .

However, it is difficult to detect the absolute position of each axis with high accuracy in a mechanical device to which the servo actuator is applied because there is a temperature change due to an uncertain external environment. Normally, to measure the rotational position of a motor, a sensor is attached to the rotor, and an element (Hall element) for detecting the magnitude of magnetic flux density is placed at the origin of the pole axis. Then, position detection is performed based on the output signal from the Hall element. The magnetic flux density of the sensor magnet is determined by the maximum magnetization and the rotational position, but the magnitude of the maximum magnetization is easily affected by temperature (generally, the maximum magnetization changes in inverse proportion to temperature).

In particular, in the above-mentioned servo-actuator for a legged mobile robot, the drive circuit is built into the actuator-unit and integrally formed. There is a problem that the temperature rise inside the unit greatly affects the position sensor signal. For this reason, sufficient measurement accuracy cannot be obtained with conventional sensors, and a sensor and a sensor output detection circuit that take into account the effect of the external environment temperature are required, but this increases equipment costs and increases equipment size. And other problems.

For example, as a result of errors in the measurement accuracy of the rotation axis due to noise, a legged mobile robot cannot maintain posture stability and may even fall. If the aircraft falls, the robot itself will be damaged, and other unforeseen events will occur, such as damage to workers near the aircraft and destruction of collision objects.

[Disclosure of the Invention] An object of the present invention is to provide an excellent servomotor that can be applied to mechanical devices of a multi-axis drive system such as a robot, a general-purpose assembly device, a robot, a hand device, and many other multi-axis control devices. The act is to provide an evening.

It is a further object of the present invention to provide an excellent servo-actuator and a position detecting device capable of detecting a posture position of a rotating shaft with high accuracy. A further object of the present invention is to provide an excellent position detecting device which can be applied to a servo-actuating unit configured by incorporating a drive circuit in the same motor unit. It is in.

A further object of the present invention is to provide an excellent servo actuator and a position detecting device capable of detecting the position of the rotating shaft with high accuracy without being affected by a temperature change in the motor unit. To provide. The present invention has been made in consideration of the above problems, and a first aspect thereof is as follows.

The present invention has been made in consideration of the above problems, and a first aspect of the present invention is to dispose a permanent magnet on the rotor side and a coil on the stator side to disperse the magnetic flux distribution and the passing current of the coil. A type of servo actuator that generates torque by

A first rotation position detection unit that detects a rotation position of the rotor,

A deceleration unit for decelerating the rotation of the rotor,

A second rotation position detection unit that detects a rotation position of an output shaft of the speed reduction unit; and a process of calculating a rotation position of the rotor based on each detection output of the first and second rotation position detection units. Department and

A feature of the present invention.

The absolute rotation position of the rotor detected by the first rotation position detection unit is> _Β (0 <θ _Μ < _2π ), the reduction ratio of the reduction unit is _Gn, and the second rotation position detection is When the absolute rotational position detected by the unit is (0 <0 _s <2 TT) and the integer part of 6> _g x G _n / 27T is N, the processing unit calculates 0 _n + N x 2 ΤΓ The absolute rotational position of the rotor Can be calculated. Here, the value obtained by converting [rad] to a digital value by arithmetic processing by a circuit or the like is defined as 0 _Bd, and the value obtained by converting 0 _g [rad] to a digital value by arithmetic processing by a circuit or the like is expressed as S _gd .

Therefore, the resolution of the absolute rotation position of the servo unit is the resolution obtained by multiplying the gear ratio G _n of the resolution of the detection signal _d of the position detection system on the rotation axis of the rotor. For this _reason , the detection value 0 _gd of the rotational position 0 _g of the output shaft in the deceleration unit is sufficient if it has a resolution enough to identify the number of rotations of the rotor per rotation of the output shaft. You.

For example, a 1 0 2 4 pulses / rotation detection value _d of the rotational position _(a rotor in one revolution, when 4 the speed reduction ratio G _n, 1 0 2 4 x in one rotation of the output shaft in the deceleration section 4 = 4 0 9 6 pulses Z rotation, so high-precision absolute rotation position can be detected, where the detection value of the rotation position on the output shaft side of the reduction unit> _gd is 4 pulses / rotation In practice, it is possible to realize high-precision, high-resolution absolute rotation position detection with a resolution of 8 pulses / rotation, taking into account the rounding error caused by the calculation.

The accuracy of the absolute rotational position of the rotor obtained in this way is actually determined by the resolution of the A / D conversion circuit, and the value of the rotational position S _gd obtained by the equation described below is affected by the temperature. Detection is possible without depending on the maximum magnetization of the magnet / sensor sensitivity. That is, it is possible to suppress the influence of the temperature change on the rotation position detection accuracy.

The speed reducer may be directly connected to a rotation shaft of the rotor, and may be integrally formed with a unit accommodating the stator and the rotor.

Further, the first and / or second rotational position detecting section includes a sensor magnet magnetized on the surface thereof and having a sine wave magnetized thereon and coaxially mounted on a rotating shaft, and the sensor magnetnet magnetized. Using two rotational position sensors, such as two Hall elements, that detect the magnitude of the magnetic flux density and are disposed at a position facing the surface with a phase difference of about 90 degrees around the rotation axis. And at a low cost.

Further, the second aspect of the present invention relates to a method of arranging a permanent magnet on the rotor side and arranging a coil on the stator side to generate torque by magnetic flux distribution and current passing through the coil. A position detecting device for detecting an absolute rotational position of a rotor in a sub-vehicle of the Eve,

A second rotation position detection unit that detects a rotation position on an output shaft of a reduction unit that reduces the rotation of the rotor;

A processing unit that calculates a rotation position of the rotor based on each detection output of the first and second rotation position detection units;

A position detecting device comprising:

Absolute rotational position ^ (0 <θ "<2 7Γ) of the rotor detected by the first rotational position detecting unit and to the reduction ratio of the reduction unit and G _n, the second rotational position detecting unit When the absolute rotational position detected in is set to (0 <6> _κ <2ττ) and the integer part of 6> _g x G _n / 27T is set to Ν, the processing unit _calculates 0 _m + N x 27T Thus, the absolute rotational position of the rotor can be calculated.

Therefore, the resolution of the absolute rotational position of the servo factory is the resolution obtained by multiplying the gear ratio _Gn of the resolution of the detection signal _d of the position detection system on the rotation axis of the rotor. From this, it is sufficient that the detected value of the rotational position of the output shaft in the deceleration section » _gd has a resolution enough to identify the number of rotations of the rotor per rotation of the output shaft.

The accuracy of the absolute rotational position of the rotor obtained in this way is actually determined by the resolution of the A / D conversion circuit, and is detected independently of the maximum magnetized sensor sensitivity of the magnet affected by temperature. can do. That is, it is possible to suppress the influence of the temperature change on the detection accuracy of the rotational position.

Further, the first and / or second rotational position detecting section may include a sensor magnet whose surface is subjected to a sine wave magnetizing process and which is coaxially mounted on a rotating shaft, and a magnetizing of the sensor magnet. Using two rotational position sensors, such as two Hall elements, that detect the magnitude of the magnetic flux density and are disposed at a position facing the surface with a phase difference of about 90 degrees around the rotation axis. And at a low cost. Further objects, features, and advantages of the present invention will become apparent from the more detailed description based on the embodiments of the present invention described below and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a cross-sectional configuration in the axial direction of a servo factory 10 used for carrying out the present invention.

FIG. 2 is a diagram illustrating a state in which the surface of the rotor sensor / magnet 15 is subjected to a sine wave magnetizing process.

FIG. 3 shows that two rotation position sensors 16 A and 16 B are arranged on the surface of the control circuit board 13 on the side of the rotor 11 with a phase difference of 90 degrees with respect to the rotation axis. FIG.

FIG. 4 is a diagram showing the configuration of the speed reducer sensor / magnet 25 and the speed reducer rotational position sensor 26A / 26B.

FIG. 5 is a block diagram showing a servo control configuration of the servo factory 10.

FIG. 6 is a chart showing a relationship between a temperature change and a sensor signal.

FIG. 7 is a chart showing a change in the output of each rotation position sensor when the rotor 11 is driven to rotate.

FIG. 8 is a block diagram in which the arithmetic processing for converting the rotational position ^ of the rotor 11 into the detection value _d of the position detection system is realized by a digital circuit.

FIG. 9 is a block diagram in which a calculation circuit for _converting the rotation position on the output shaft side in the reduction unit to the detection value 0 _gd of the position detection system is realized by a digital circuit.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an axial cross-sectional configuration of a servo factory 10 used in the embodiment of the present invention.

As shown in the figure, the servo factory 10 has, for example, a three-phase stator 12 arranged circumferentially around a rotor 11 having a predetermined rotation axis. A permanent magnet is arranged on the rotor 11 side, and a coil is arranged on the stator 12 side, and a sine wave current is supplied to the coil to form a desired sine wave magnetic flux distribution. A rotating torque can be applied. The rotor 11 and the stator 12 are housed in a substantially cylindrical casing, and constitute a single servo unit. The rotor 11 is rotatably supported around a predetermined rotation axis.

Servo • Use a magnet with high magnetic flux density on the rotor side to achieve a smaller motor and higher output. For example, a polar anisotropic magnet has a high magnetic flux density, and is therefore excellent in increasing output. For example, Japanese Patent Application Laid-Open Publication No. 2001-314150 (Japanese Patent Application No. 2000-2012) already assigned to the present applicant discloses miniaturization and high output. For example, a semiconductor device using a polar anisotropic magnet for the rotor is disclosed.

In addition, the winding density on the stator side will be increased in order to realize the miniaturization and high output of servos and motors. For example, a split core method is adopted for the stator. The split core method is to divide the iron core, that is, the core in the circumferential direction, wind the windings in an externally aligned manner, and then assemble each iron core to form a stator. Enables high-density winding and space savings in the practice. For example, Japanese Patent Application Laid-Open Publication No. 2000-95192 (Japanese Patent Application No. 2000-1982), which has already been assigned to the present applicant, discloses that a coil is attached to a stator. It discloses a servo factory that employs a split core system for suitable winding.

The servo amplifier 10 according to the present embodiment is a small amplifier that incorporates the drive circuit 13A in the same housing. In the illustrated example, printed wiring of a predetermined pattern is laid on the control circuit board 13 and peripheral circuits for controlling supply of a sine wave current to the drive circuit 13 A and the stator coil are provided. A circuit chip is mounted. The control circuit board 13 is formed in a substantially disk shape. Approximately in the center of control circuit board 13 An opening for penetrating the rotating shaft of the rotor 11 is provided.

A ring-shaped rotor sensor 'magnet 15' is attached to an end face of the rotor 11 on the control circuit board 13 side. The surface of the ring-shaped rotor sensor / magnet 15 is subjected to a sine wave magnetizing process as shown in FIG.

The surface of the ring-shaped rotor sensor and magnet 15 is sine-wave magnetized (described above), and its magnetic flux density ø is expressed as a function of the rotational position 6> _n of the rotor 11. In the present embodiment, it is assumed that the magnetic flux density _Β (Θ _Β ) of the rotor sensor / magnet 15 changes according to the following equation. X sir (0 _w ) [T] where the absolute rotational position of rotor 11 is from 0 to 27r x _Gn every time a reducer with a reduction ratio _Gn (described later) makes one rotation. Change. _Further, 0 Π = Ο is defined as an origin position of the polar axis at the output the magnet Bok of the rotary shaft the rotor 1 1. ø. (T) is the magnitude of the maximum magnetic flux density of the magnet and depends on the temperature t [° C]. In general, the maximum magnetic flux density 00 (t) of a magnet changes in inverse proportion to the temperature t. That is, the magnitudes of the amplitudes of the outputs of the rotation position sensors 168 and 16B change with the temperature t.

On the other hand, on the surface of the control circuit board 13 on the rotor 11 side, as shown in FIGS. 1 and 3, two rotation position sensors 16 A and 16 B They are arranged with a phase difference of degrees.

Each of the rotation position sensors 16A and 16B is composed of an element (Hall element) for detecting the magnitude of the magnetic flux density at the origin position of the magnetic pole axis. The rotation position sensors 168 and 16B are arranged to face the magnetized surface of the rotor sensor / magnet 15. One rotational position sensor 16A outputs a Hall sensor signal SIN according to a magnetic field generated by a rotor sensor and a magnet, and the other rotational position sensor 16B similarly outputs a Hall sensor signal COS. . See Figure 7 for details. The SIN signal and the COS signal as these sensor outputs are input to the drive circuit 13A.

The Hall sensor signals SIN and COS are used to detect the absolute position of the drive circuit 13 A. It is input to the output circuit (reference number 30 in FIG. 5) and is converted to a digital value 0 _Bd as shown in FIG. Since the detected value 0 _Bd is controlled by the digital circuit shown in FIG. 8 so that 0 _B = 0 _{× Q} , the amplitude A changes depending on the temperature t of the sensor signals S IN and COS. Is independent of. The [pulse] obtained in this manner represents the absolute rotational position of the rotor 11 of the servo actuator 10. That is, the driving circuit 13 A, as that Itasu position command and absolute rotational position 0 _nd guard from the outside (for example, a central controller) performs feedback control of Akuchiyue Isseki 'mode evening rotary drive.

Further, on the left side in FIG. 1, a reduction gear unit 20 for reducing the rotational drive of the rotor 11 is directly connected to the rotational shaft of the rotor 11. In the present embodiment, the reduction gear unit 20 includes a plurality of reduction gear planetary gears 21-1, 21-2, and 21-3.

On an end face of the reduction gear section 20, a connection section 28 that is connected to a member outside the servo mechanism 10 is attached so as to rotate substantially coaxially with the rotation axis of the rotor 11. The ring-shaped reducer sensor 'magnet 25 is attached to the connecting portion 28 so as to rotate substantially coaxially with the rotation axis of the rotor 11. The surface of the speed reducer sensor magnet 25 is subjected to a sine wave magnetizing process as shown in FIG.

On the other hand, two reducer rotational position sensors 26A and 26B are disposed so as to face the reducer sensor 'magnet 25 with a phase difference of 90 degrees with respect to the rotation axis.

The rotation position sensors 26A and 26B are configured by elements (Hall elements) that detect the magnitude of the magnetic flux density at the origin position of the magnetic pole axis. The rotation position sensors 26 A and 26 B are arranged to face the magnetized surface of the rotor sensor / magnet 25. One rotational position sensor 16A outputs a hall sensor signal SIN corresponding to the magnetic field generated by the rotor sensor magnet, and the other rotational position sensor 26B similarly outputs a hall sensor signal COS. See Figure 7 for details. ABS-SIN signal and A BS- COS signal of by these sensor output _c thereof Hall 'sensor signals ABS SIN and ABS COS inputted to the drive circuit 13 A, the driving circuit 1 The signal is input to the 3 A absolute position detection circuit (reference number 30 in Fig. 5) and is controlled by a digital circuit as shown in Fig. 9 so that 0 _g = 6 _x , so that the sensor signal ABS_S IN and ABS — The result is independent of the amplitude A, which varies with the temperature t of COS. The 6> _gd [pulse] thus obtained represents the absolute rotational position of the reducer of the servo actuator 10 on the main shaft side. The drive circuit 13A performs feedback control of the rotational drive of the actuator so that the position command from the outside (for example, the central controller) and the absolute rotational position match.

Fig. 5 shows the servo control configuration of the servo actuator. For example, in the case where the servo actuator 10 is applied to the joint actuator of a legged mobile robot, the feedback control of the actuator is significantly related to the attitude stabilization control of the aircraft.

Although the absolute position detection circuit 30 is a circuit module for detecting the absolute rotation position 0 _g of the output shaft of the servo actuator 10, in the present embodiment, the absolute position of the rotation shaft of the rotor 11 is Rotary position sensor that measures position 0 _{B In addition} to the SIN signal and COS signal that are the outputs of 16 A and 16 B, a reducer rotational position sensor that measures the absolute position 0 _g on the output shaft on the reduction gear section 20 side 26 A and 26 B, the output of AB S—S IN signal and ABS—COS signal are input, and the absolute position on the rotor 11 side and the absolute position on the output shaft side> _g Detects high-resolution absolute position of output shaft based on

From the rotation sensors 26A and 26B, the output shaft rotation angle and the sensor signal of the hall element, which are expressed by the following equation, are obtained. See Figure 7 for details.

M

Here, GD (t) is a sensitivity coefficient of the Hall element constituting each rotation position sensor, and depends on the temperature t [° C]. In general, G. (T) varies inversely with temperature t. Figure 6 shows the relationship between the temperature change and the sensor signal. As you can see from the figure In addition, the output 0 _S of the Hall element has a large amplitude at low temperatures, but has a small amplitude at high temperatures. That is, the sensitivity of the sensor decreases as the temperature rises.

Maximum magnetic flux density of the magnet ø. (T) and the sensitivity G of the Hall element. (t) has the characteristics shown in the following equation at the maximum operating temperature range.

0. (R = 0 _o x (l— xi) [cho]

G ₀ {t) = G _o x {lk _v xt) where φ _ϋ , G. Is the maximum magnetic flux density at t = 0, the sensitivity and the magnitude of each. Also, kk _g is a positive constant, which is approximated by the relational expression shown below.

0 <l, 0 <(k, xt) <

The procedure for determining the rotational position> _g of the output shaft of the servo actuator from these two signals will be described below.

The sensor signals ABS-SIN and ABS_C0S of the speed reducer rotation position sensors 26A and 26B are input to the drive circuit 13A built in the servo actuator 10. The A / D conversion circuit converts the sensor signals ABS-SIN and ABS-COS to digital-format data.

Drive circuit 13 A, the sensor signal AB S- S IN and ABS-COS relationship Yori, determines the approximate value of the rotational position 6 _»g according to the following equation.

(1) When ABS SIN 0 and ABS COS≥0, 0≤

'' One ⁸ ≤12

(2) ABSπ≤> when ABS SiN≥0 and ABS COS <0. r

, ' ^{--2 g}

(3) When ABS SIN <0 and ABS COS <0, r <(. <

'' One ^g 2

(4) When ABS SIN <OR-DABS COS≥0,; r≤ <

'One 2 ^s

Here, the value of S _g is determined in each of the regions (1) to (4). Then, ^ and Θ _、,

In the (17) region, 6 » _s = 0, θ _ε = -π (27) In the region, = -π, θ _ε = π

(3) In the 0 region, θ ₅ = π, θ _ε = π

(4) In the C area,

Then, the calculation of the following equation is performed. θ _χ = θ _$

ί formula _{1) £ (Χ = (ABS_SIN} ) x cos θ χ one (ABS_C S) x sin6>

= G. _{(i) x0 o (i)} xsin (^ I) If, in case it is not E0 _X = O is, 0 _X to be updated as the following equation, by changing the ₀ Χ until convergence to ΕΘχ = 0 Recalculate from the above formula. (Equation 2) θ _χ = θ _χ + θ ₀

However, θ χ ≤θ _{_ε.} Positional displacement amount of the minimum bit value of AZD converter

When the _Ε 6 »χ = 0 is a θ ε = θ _{_χ.} Therefore, this _Χ value becomes the absolute position 0 _gd of the output shaft of the servo unit 10. FIG. 9 shows a block diagram in which the above operation is realized by a circuit.

The accuracy of the _gd value obtained in this way is actually determined by the resolution of the A / D converter, and is affected by temperature G. (T) and _Ό (t) can be detected. That is, it is possible to suppress the influence of the temperature change on the rotation position detection accuracy.

According to the present invention, a relatively low-resolution circuit and a circuit using an analog signal having a normal SN ratio can be used to achieve a high-precision and high-resolution absolute position on the output shaft of a servomotor. Can easily be detected.

The absolute rotational position detected from the rotation position sensor 1 6 A and 16 B in the rotor 1 1 side of the servo 'Akuchiyue Isseki 10 6> _[pi and _{(0 <θ α <2π)} , the reduction ratio of the decelerator _Gn, and the absolute rotation position detected by each reduction gear rotation position sensor 26A and 26B attached to the output shaft side of the reduction gear unit 20 is 6> _g (0 < _θε <2π). At this time, if the integer value of the operation result of 0 _g x _G ₁₁ / 27r is N, then when the output shaft rotates by, Ν is the number of times the rotating shaft of the rotor 11 has rotated. As a result, the absolute position of the rotation axis of the rotor 11 can be calculated from 0 _n + Nx 2ΤΓ. Therefore, the resolution of the absolute rotation position of the servo factory 10 is the resolution obtained by multiplying the resolution of the detection signal ^ of the position detection system on the rotation axis of the rotor 11 by the gear ratio _Gn . From this, it is sufficient for the detection system of the rotation position 6 _{g on} the output shaft of the reduction gear unit 20 to have a resolution enough to identify the number of rotations of the rotor 11 per rotation of the output shaft. .

Further, the backlash of the reduction gear, 0 _[pi and (deviation amount of zero point of _g, and the deviation amount of zero point of the 0 _B by the tolerance of the arrangement of the sensor, if known, the shift amount By correcting the magnitude, the zeros of 0 _B and 0 _g can be adjusted, so that the zeros of and 6> _g do not have to match. FIG. 7 shows a change in the output of each rotation position sensor when the rotor 11 is driven to rotate. Assuming that the detected value _d of the rotation position ^ of the rotor 1 1 is 1024 pulses / revolution in one revolution and the reduction ratio _Gn is 4, 1024 x 4 = 4096 pulses / revolution in one revolution of the output shaft in the reduction gear unit 20 Therefore, a highly accurate absolute rotational position can be detected. At this time, the detection value> _gd rotational position> _g on the output shaft side of the reduction gear unit 20 is sufficient only provides a resolution of 4 pulses / rotation. Fig. 7 shows an example when the detection value is 0 _{gd and} the resolution is 1024 pulses / rotation. In this case, N = 0 when 0≤d _si <256, N = l when 256≤0 _gd <512, Ν = 2 when 512≤θ _≠ <768, and 768≤6> _gd <1024 Then N = 3.

In this way, it is possible to detect the rotation axis of the evening sun with high resolution using the two built-in position detectors with relatively low resolution. Supplement

The present invention has been described in detail with reference to the specific embodiments. However, it is obvious that those skilled in the art can modify or substitute the embodiment without departing from the gist of the present invention. That is, the present invention has been disclosed by way of example, and should not be construed as limiting. In order to determine the gist of the present invention, the claims described at the beginning should be considered.

[Industrial applicability] According to the present invention, the present invention can be applied to mechanical devices of a multi-axis drive system such as a robot, a general-purpose assembly device, a robot's hand device, and other multi-axis control devices. Able to provide excellent servos.

Further, according to the present invention, it is possible to provide an excellent servo actuator capable of detecting a posture position of a rotating shaft with high accuracy and a position detecting device therefor. Further, according to the present invention, an excellent position detecting device which can be applied to a servo-actuating unit having a driving circuit built in the same motor unit. Can be provided.

Further, according to the present invention, it is possible to detect an attitude position of a rotating shaft with high accuracy without being affected by a temperature change in a motor unit. An apparatus can be provided.

Claims

The scope of the claims

1. A type of servo actuator in which a permanent magnet is arranged on the rotor side and a coil is arranged on the stator side to generate torque by magnetic flux distribution and current passing through the coil.

A deceleration unit for decelerating the rotation of the rotor,

The servo is characterized by having the following.

2. The servo according to claim 1, wherein the speed reducer is directly connected to a rotation shaft of the rotor, and is integrally formed with a unit accommodating the stator and the rotor. 'Akchi Yue overnight.

3. The first and / or second rotational position detection unit is:

A sensor magnet with a sine wave magnetized surface and coaxially mounted on the rotating shaft;

Two rotation position sensors, which are arranged around the rotation axis with a phase difference of about 90 degrees at a position facing the magnetized surface of the sensor magnet and detect a magnitude of a magnetic flux density;

2. The apparatus according to claim 1, further comprising:

4. The processing unit sets the absolute rotation position of the rotor detected by the first rotation position detection unit to (0 <θ, <2π), sets the reduction ratio of the reduction unit to _Gn , When the absolute rotation position detected by the rotation position detection unit 2 is 0 _g (0 2 27Γ) and the integer part of 0 _g x G _n / 27 とした is N, the rotation is performed by NX27Γ. 2. The servo actuator according to claim 1, wherein the absolute rotational position of the slave is calculated.

5. A permanent magnet is arranged on the rotor side, and a coil is arranged on the stator side to detect the absolute rotational position of the rotor in a servo factory that generates torque by magnetic flux distribution and current passing through the coil. A position detecting device,

A position detecting device comprising:

6. The position according to claim 5, wherein the speed reduction portion is directly connected to a rotation shaft of the rotor, and is integrally formed with a unit that accommodates the stator and the rotor.

7. The first and / or second rotational position detection unit includes:

Two rotation position sensors that detect the magnitude of the magnetic flux density and are disposed at a position facing the magnetized surface of the sensor magnet with a phase difference of about 90 degrees around the rotation axis;

6. The position detecting device according to claim 5, comprising:

8. The processing unit sets an absolute rotation position of the rotor detected by the first rotation position detection unit to _0Β (0 <θ, <2π), a reduction ratio of the reduction unit to G _n , the absolute rotational position detected by the second rotation position detector 6> and _g (0 ° 0 _g <27T), 0 when the _g G _n / 2 integer portion of 7Γ was n, said by 0 Π ₊ Νχ2ττ 6. The position detecting device according to claim 5, wherein an absolute rotational position of the rotor is calculated.