JPH07110151B2 - Direct drive motor system - Google Patents

Description

The present invention relates to a direct drive motor system used for driving joints of a multi-joint type robot.

[Prior Art] A drive system using a DC motor and a speed reducer is often used in applications such as joint drive of an articulated robot that requires high torque at low speed. However, in consideration of the life of the brush and reducer of the DC motor, maintenance of the lubricating oil, etc., direct drive by the inductor type motor (Direct
Drive = DD) is ideal.

The control system of the DD motor is provided with a position control section for feedback controlling the rotational position of the motor, a speed control section for feedback controlling the rotational speed of the motor, and a commutation control section for commutating control of the motor. There is.

In a conventional DD motor control system, a signal used for position control, a signal used for speed control, and a signal used for commutation control are obtained from separate circuits. Therefore, there is a problem that the circuit configuration becomes complicated.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems, and is a signal used for position control of a motor, a signal used for speed control, and a signal used for commutation control. It is an object of the present invention to realize a direct drive motor system capable of performing position control, speed control and commutation control of a motor with a simple circuit configuration by simultaneously obtaining and with a single encoder interface.

[Means for Solving the Problems] The present invention relates to a direct drive type motor unit in which a rotor is arranged outside and a stator is arranged inside, and an encoder which detects rotation of the motor unit and outputs a detection signal. Section, a speed control section that feedback-controls the rotation speed of the motor section based on the detection signal of the encoder section, and a position control that feedback-controls the rotation position of the motor section based on the detection signal of the encoder section. Section, and commutation control means for controlling commutation of the motor section based on a detection signal of the encoder section, the encoder section is composed of an encoder and an encoder interface, the encoder is an optical A rotary encoder, which is provided with two stages of translucent slit rows, and has translucent slit rows on the outer side and the inner side. The difference in the number of slits is the same as the number of teeth of the motor section, a light source for projecting light on each of the light-transmitting slits in the two-stage light-transmitting slit rows, and photodiodes arranged in an array. And an image sensor for detecting light passing through the light-transmitting slits in the two rows of light-transmitting slits, and the encoder interface has a cycle counter for counting the cycle of the detection signal of the image sensor. , The phase difference between the detection signal of the image sensor that detects the light passing through the light transmitting slits in the outer light transmitting slit row and the detection signal of the image sensor that detects the light passing through the light transmitting slits in the inner light transmitting slit row A phase difference counter for counting, and a signal used for position control of the motor unit based on the cycle counted by the cycle counter, A signal used for speed control of the motor unit is obtained based on the frequency of the sensor detection signal, and a signal used for commutation control of the motor unit is obtained based on the phase difference counted by the phase difference counter. It is a direct drive motor system.

[Examples] The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an embodiment of a DD motor system according to the present invention.

In the figure, 100 is a motor section, 200 is a drive circuit for driving the motor section 100, 300 is a rotation of the motor section 100 detected by an encoder 300 ₁ , and an encoder interface (hereinafter referred to as an encoder interface).
An encoder unit that outputs a detection signal via 300 ₂ , 400 is a speed control unit that feedback-controls the rotation speed of the motor unit 100, 500 is a position control unit that feedback-controls the rotation position of the motor unit 100, and 600 is This is a tuning unit that adjusts the servo system of the speed control unit 400 and the position control unit 500.

The specific configuration of these is shown in FIG.

In the figure, the motor unit 100 is an inductor type motor having three sets of stators arranged on the outside and inside the rotor. Motor part 100
FIG. 3 shows a concrete configuration example of the above.

3A is a front view of the motor unit, and FIG. 3B is a sectional view of the same.

In this motor, in order to increase the radius of the rotor, the motor is arranged outside, the stator is arranged inside, and the static magnet is arranged on the stator side.

An inner stator 101 is composed of two magnetic bodies 101a and 101b, a static magnet (permanent magnet, electromagnet, etc.) 102 connecting the two, and an exciting coil described later.

Each magnetic body 101a and 101b has six salient poles 103a _{1 to} 105a ₁ , 1
There are 03a _{2 to} 105a ₂ and 103b _{1 to} 105b ₁ and 103b _{2 to} 105b ₂ , and the teeth of the pitch P are provided at the tip of each salient pole. The teeth of adjacent salient poles, for example, the teeth of 103a ₁ and 104a ₂ are 1/3 of each other.
Pitch (P / 3) phase shift is provided, and the salient poles of the two magnetic bodies 101a and 101b facing each other, for example, salient poles 103a ₁ and 103b.
₁ has the same phase. 106a-106c and 107a-107c
Is an exciting coil which is provided in each salient pole portion, and two of each of them are connected in series, that is, 106a and 107a, 106b and 107b, 106c and 107c), and 108 is a magnetic body and is internally toothed at a pitch P. Is a rotor provided with. Rotor 108 is 108
It consists of a and 108b, and their teeth are offset by 1/2 pitch.

In the motor configured as described above, the exciting coil 106a and
If currents (sine wave, pulse wave, etc.) with a phase difference of 120 ° are applied to 107a, 106b and 107b, 106c and 107c, they will rotate.
The rotation direction can be switched by advancing or delaying this phase. The magnetic flux of the static magnet 102 and the magnetic flux of the exciting coil 106a are alternately added or subtracted in the gaps 109a and 109b, and the pulse motor rotates with high resolution. Since the magnetic flux generated by the static magnet 102 generates half of the magnetic flux required for this rotation, it consumes less power and improves efficiency. The permanent magnet used as a static magnet here is installed on the stator side because the surface magnetic flux density of the magnet is at most 1T.
This is because it is as small as (Tesla), so a certain size is required, and when it is placed on the rotor side, the radial thickness becomes large. The number of salient poles can be arbitrarily selected as long as it is a multiple of 3 other than 6.

The motor having such a configuration can generate a significantly larger torque than a motor having the same outer diameter and the same shaft diameter.

Returning to FIG. 2, the drive circuit 200 will be described.

In the drive circuit 200, 201 and 202 are coils L ₁ and L of the motor section.
₂ , a current detection circuit for detecting the exciting current flowing in ₂ , 203, 204 are current command values from the speed control unit 400 and the current detection circuits 201, 202
It is a subtractor that takes the difference of the detection current of. 205 is a power amplification circuit that turns on the transistor of the excitation circuit 207 for the PWM signal generated by the PWM circuit 206 based on the signals from the subtracters 203 and 204.
When turned off, a three-phase sinusoidal current is passed through the motor so that the difference current between the subtractors 203 and 204 becomes zero.

Here, a specific configuration example of the current detection circuits 201 and 202 is shown in FIG.

In the figure, X ₁ is an input circuit, X ₂ is an output circuit, and TR is a transformer.

The transformer TR includes a primary winding n ₁ to which the input circuit X ₁ is connected,
An output circuit X ₂ is connected secondary winding n _2, consisting of the tertiary winding n ₃ disposed between the primary and secondary windings.

In the input circuit X ₁ , d ₁ and d ₂ are input terminals and are connected to the line 1 in FIG. 2 in which the exciting current flows.

r is a resistor connected between the input terminals d ₁ and d ₂ , and an exciting current I of the motor coils L ₁ and L ₂ flows. A series circuit of the resistor R ₁ and the capacitor C ₁ is connected in parallel with the resistor r. The resistance value of the resistor r is, for example, about 5 mΩ, which is sufficiently smaller than the resistance value of the resistor R ₁ . Further, a series circuit of the parallel diode circuit D ₁ and the primary winding n ₁ is connected in parallel with the capacitor C ₁ . The parallel diode circuit D ₁ consists of diodes D ₁₁ and D ₁₂
Are connected in parallel with opposite polarities.

In the output circuit X ₂ , d ₃ and d ₄ are output terminals. Output terminal d ₃ , d ₄
A low pass filter (hereinafter referred to as LPF) F and resistor R
A series circuit of ₂ and capacitor C ₂ is connected. A series circuit of a parallel diode circuit D ₂ and a winding n ₂ is connected to both ends of the capacitor C ₂ . The capacitor C ₂ constitutes an averaging means. The parallel diode circuit D ₂ has the same configuration as the parallel diode circuit D ₁ .

Voltage e ₁ applied to parallel diode circuits D ₁ and D ₂ and flowing current i
The relationship of ₁ becomes a non-linear relationship as shown in FIG.

OS is a pulse generator and is connected to the winding n ₃ via a resistor R ₃ and a capacitor C ₃ .

In the circuit configured in this way, when the winding ratio of the primary winding n ₁ to the secondary winding n ₂ of the transformer TR is set to 1: 1 and a positive / negative symmetrical impulse signal is given to the tertiary winding n ₃ , its equivalent is obtained. The circuit is as shown in FIG.

In the equivalent circuit of FIG. 6, the input voltage E _i is rI (resistance r
The resistance value of is also represented by r).

The switches S ₁ and S ₂ represent switching operations of the diodes D ₁₁ , D ₁₂ , D ₂₁ and D ₂₂ , and when a positive impulse is applied from the pulse generator OS, the switches S ₁ and S 2 are ₂ is connected to the contact g ₁ side (diodes D ₁₁ and D ₂₁ are conducting), and when a negative impulse is applied, the switches S ₁ and S ₂ are connected to the contact g ₃ side (diodes D ₁₂ and D 2 D ₂₂ is conducting). In addition, when no impulse is applied, the switches S ₁ , S
₂ is connected to contact g ₂ (none of the diodes are conducting). Each of the diodes D _{11 to} D ₂₂ has a forward voltage Δ
And a dynamic resistance (forward resistance) r are connected in series.

Now, in the state where the positive impulse i ₀ is applied from the pulse generator OS, the switches S ₁ and S ₂ are equivalent to being connected to the contact g ₁ (diodes D ₁₁ and D ₂₁ are conducting), The impulse i ₀ is shunted equally to the diode D ₁₁ side and the diode D ₂₁ side by i _0/2 as shown in the figure. In this state, the output voltage E ₀₁ between the output terminals d ₃ and d ₄ can be expressed by an equation.

Further, in the state where the negative polarity impulse i ₀ (the amplitude is the same as the case of the positive polarity) is applied, the output voltage E ₀₂ between the output terminals d ₃ and d ₄ can be expressed by an equation.

Positive and negative polarity impulses from the pulse generator OS are applied in a repeating cycle T as shown in FIG. 7 (a), and the capacitances of the capacitors C ₁ and C ₂ are reduced in potential change due to charge / discharge of impulses. If you make it big enough,
The output voltage E ₀ is the average value of E ₀₁ and E ₀₂ , and can be expressed by the following equation.

If Δ ₁₁ = Δ ₁₂ , Δ ₂₁ = Δ ₂₂ r ₁₁ = r ₁₂ , r ₂₁ = r ₂₂ in the equation, the second and third terms are both 0,
The output voltage E ₀ becomes equal to the input voltage E _i . Therefore, the voltage E _i applied to the input circuit can be electrically insulated and taken out from the output circuit side.

Here, the conditions shown in the equation can be easily realized by using elements of the same standard for the elements D ₁₁ and D ₁₂ and D ₂₁ and D ₂₂ that form the parallel diode circuit, or keeping them at the same temperature.

FIG. 7 is an operation waveform diagram in FIG. 6, where (a) is a positive and negative polarity impulse from the pulse generator OS, (b) is a current shunted to the parallel diode circuits D ₁ and D ₂ , and (c) is Is the output voltage. Here, the ripple component of the output voltage E ₀ is exaggerated.

Returning to FIG. 2 again, the configuration of the encoder unit 300 will be described.

First, the configuration of the encoder I / F 300 ₂ will be described. FIG. 8 is a diagram showing a configuration example of the encoder I / F 300 ₂ .

In the figure, 301 is a disc-shaped code plate, and is provided with two stages of translucent slit rows in which translucent slits are arranged at a predetermined pitch in the circumferential direction. The outer slit row is provided with m ₁ transparent slits 302, and the inner transparent slit row is m ₂
Individual light-transmitting slits 303 are provided. These translucent slits 302 and 303 are provided to detect the positional deviation between the teeth of the rotor and the stator of the motor. As a slit for detecting the rotational position of the code plate 1, the slit 302
A slit S for detecting the origin is provided outside the. The code plate 301 rotates integrally with the output shaft of the motor.

Reference numerals 304 and 305 denote light sources, and 306 and 307 are lenses for collimating the light beams from the light sources 304 and 305.

The light that has passed through the lens 306 is passed through the slits 302 and S to the lens 7
The light that has passed through hits the slits 3, respectively.

308 is an image sensor for receiving the light (slit image) having passed through the light transmitting slits 302, for example, eight photodiodes 308 _{1 to 308 8} in which are arranged in an array. G ₁ , G
Reference numeral ₂ is a photodiode that detects light that has passed through the light-transmitting slit S.

Reference numeral 309 denotes an image sensor that receives light (slit image) that has passed through the light-transmitting slit 303, and has, for example, eight photodiodes 309 _{1 to} 309 ₈ arranged in an array.

These photodiodes are arranged within one pitch P'of the light-transmitting slits as shown in FIG.

A signal processing circuit 310 includes photodiodes 308 _{1 to} 308.
₈ and 309 _{1 to 309 8} detection signal based on calculating a positional relationship between the teeth of the motor rotor and the stator.

FIG. 10 shows a specific configuration example of such a control device.
In FIG. 10, the same parts as those in FIG. 9 are designated by the same reference numerals.

In FIG. 10, SW1 to SW8 are photodiodes 308 _{1 to} 308 ₈ and 30.
Is sequentially taken out will switch the signals from 9 _{1-309 8} at a fixed timing.

Reference numerals 311 and 312 denote OP amplifiers that amplify the signals applied via the switches SW1 to SW8. The outputs of the OP amplifiers 311 and 312 have a staircase waveform. The height of the waveform corresponds to the number of photodiodes that detected light.

Next, the configuration of the encoder I / F 300 ₂ returning to FIG. ₂ will be described.

In the encoder I / F 300 ₂ , 313 and 314 are LPFs that extract low frequency components of the outputs of the OP amplifiers 311 and 312, 315 and 316 are comparators that shape the output of the LPFs 313 and 314, and 317 and 318 are period counters that count the period of the output waveforms of the comparators 314 and 316. , 319 are phase difference counters for counting the phase difference between the output waveforms of the comparators 315, 316.

Here, the signal used for commutation control is obtained as follows.

The scan frequency of switches SW1 to SW8 is 8f _s .

Optical photodiode 3 that has passed through the outer light-transmitting slit 302
Lights that have been detected by 08 _{1 to} 30 _{8 8} and have passed through the inner light-transmitting slit 303 are detected by photodiodes 30 9 _{1 to} 30 9 ₈ . switch
When the detection signals of these photodiodes are scanned at a frequency of 8f _s by scanning SW1 to SW8, the signals f ₁ (t) and f ₂ (t) that have passed through the LPFs 313 and 314 are as follows.

f ₁ (t) = A ₁ sin (ωt + m ₁ θ) (1) f ₂ (t) = A ₂ sin (ωt + m ₂ θ) (2) where A ₁ and A _{2 are} constants and θ is the code plate 301. Rotation angle, t: time ω = 2πf _s The phase difference φ between the signals f ₁ (t) and f ₂ (t) is as follows.

φ = (m ₁ −m ₂ ) θ (3) Here, the relationship between the phase difference φ and the phase shift between the teeth of the rotor and the stator of the motor will be described.

For example, the case where the number of outer light-transmitting slits m ₁ is 8 and the number of inner light-transmitting slits m ₂ is 6 will be described.

In the present invention, (the difference in the number of light-transmitting slits in the outer and inner light-transmitting slit rows) = (the number of teeth of the motor) is set. Therefore, the number of teeth n of the motor is set to 2 from 8-6. .

In this case, the relationship between the modulation amount of the phase of the signals f ₁ (t) and f ₂ (t) and the rotation angle θ of the code plate is as shown in FIGS. 11 (a) and 11 (b). The modulation amount of the phase of the signals f ₁ (t) and f ₂ (t) is
These correspond to m ₁ θ and m ₂ θ in the equations (1) and (2), respectively.

From FIG. 11, the phase shift between the signals f ₁ (t) and f ₂ (t) increases in proportion to φ ₁ , φ _2, ... In proportion to the rotation angle θ of the code plate.

The phase shift φ between f ₁ (t) and f ₂ (t) when the code plate rotates by θ is as follows from equation (3).

φ = (8−6) θ (4) On the other hand, when the code plate rotates by θ, the rotor of the motor also rotates by θ. Since the motor has two teeth, the rotor and stator teeth of the motor are out of phase with each other by an electrical angle of 2θ. That is, the phase shift φ between f ₁ (t) and f ₂ (t) becomes the phase shift itself between the teeth of the rotor and stator of the motor. Based on this, the phase shift between the teeth of the rotor and the stator of the motor is detected, and commutation control of the motor is performed based on the detected phase shift. Signals f ₁ (t) and f
The phase shift φ of ₂ (t) is measured by the phase difference counter 319.

Next, the configuration of the speed control unit 400 will be described.

In the speed control unit 400, 401 is a switch for switching between speed control and position control. This switch is connected to the contact h ₁ side for speed control, and connected to the contact h ₂ side for position control. 402 is an F / V converter, encoder I / F 300 ₂
The output signal of is converted into a speed signal.

403 is a signal from the switch 401 (which is the speed command value)
It is a subtractor that takes the difference between the signals from the F / V converter 402.

404 is a multiplying digital-to-analog converter (hereinafter referred to as MDA), whose gain is changed by a digital signal and which amplifies an analog input signal. The gain setting signal is given from the position control unit 500 or the tuning unit 600.

405 is a voltage control limiter (hereinafter referred to as VCL), which is an MD
Hold the A404 output at a certain upper or lower limit.

406 and 407 are MDAs, which receive the signal from the VCL 405 and receive the current signal Isinθ _e according to the commutation control signal from the position control unit 500.
Or subtractor 2 using Isin (θ _e + 120 °) as the current command value
Give to 03,204 (I is current).

Next, the configuration of the position control unit 500 will be described.

In the position control unit 500, 501 is a counter that generates and generates a position command signal based on a position command pulse signal and a rotation direction signal, and 502 is connected to the contact k ₁ side in the normal mode,
In the test mode, the switch is connected to the contact k ₂ side to which the test signal is given by the test signal generating means 502 ′.

Reference numeral 503 is a subtracter, which takes the difference between the signal from the switch 502 (which serves as a position command signal) and the signal from the position detecting means 504.

A position control unit 505 adjusts the gain of the MDA 404 based on the parameter read from the gain table 506 by a signal from the encoder I / F 300 ₂ or the tuning unit 600. The position control means 505 is an I-PD by software.
A third-order servo system that performs (integral, proportional, differential) operation is configured.

The gain table 506 is, for example, as shown in FIG. 12, the load inertia J of the motor and the natural frequency f _n of the position control system and the optimum control parameter values x ₁₁ , x ₁₂ , x corresponding to these values.
It is a table that corresponds to ₁₃ mag. Gain table 506
There are tables for speed control and position control, and there are a table for P operation (proportional operation) and a table for I operation (integration operation) in the table for speed control and the table for position control.

507 is a multiplier 406, based on the signal from the encoder I / F 300 ₂ .
A commutation control unit that sends a signal to 407 to control the commutation of the motor, 508 is a D / A converter that converts the output of the position control unit 505 to digital / analog, and 509 is a sample of the output of the D / A converter 508.・ Sample to hold and send to tuning unit 600
Hold circuit (hereinafter referred to as S / H circuit).

When performing speed control, the switch 401 is connected to the contact h ₁ side, and the subtractor 403 calculates the difference between the analog speed input as the speed command value and the speed signal of the F / V converter 402. The gain of the MDA404 is set in the gain table 5 by the switches 601 and 602 described later.
It is set by the control parameter value read from 06.

When performing position control, the switch 401 is connected to the contact h ₂ side and the switch 502 is connected to the contact k ₁ side. Then, the position command signal from the counter 501 and the position detecting means 504
The subtractor 503 calculates the difference between the output signals of the. In the position control means 505, the switches 601 and 602 are used to read control parameters from the gain table 506, and the position control algorithm is used to adjust the gain of the MDA 404 using the control parameters.

Next, the configuration of the tuning unit 600 will be described.

In the tuning unit 600, 601, 602 are servo tuning switches. 601 is the natural frequency f within the specified range
_This is a natural frequency setting switch that sets _n in multiple stages. For example, with this switch, the natural frequency is 5-20Hz
The range is set in 16 steps.

Reference numeral 602 is an inertia setting switch for setting the load inertia J in a plurality of steps within a predetermined range.

When f _n and J are set by these switches 601, 602, the optimum control parameter value corresponding to the set value is read from the gain table 506.

When performing position control using the switches 601 and 602, the position control unit 505 adjusts the gain of the MDA 404 based on the control parameter value read from the position control table. When performing speed control, the control parameters read from the speed control table are sent to the MDA 404 to adjust the gain.

603 is a switch for switching the switch 502, 604 is a switch 401
The switch 605 is a switch for switching the speed control and the position control to the integral operation or the proportional operation. By switching this switch, the integral operation table and the proportional operation table of the gain table 506 are used properly. When moving the robot arm with the DD motor, control is performed by integral operation when positioning the robot arm.
When an object is grabbed by the robot arm, control by proportional movement (compliance control) is performed.

Reference numeral 606 is a monitor output terminal for taking out the output of the position control unit 500 via the S / H circuit 402. This output is sent to a display device such as an oscilloscope for monitoring.

Reference numeral 607 is a pulse extraction terminal for extracting an incremental pulse signal via the up / down pulse generator 608.

Reference numeral 609 is an origin signal terminal for taking out the outputs of the photodiodes G ₁ and G ₂ .

The outputs extracted from the pulse extraction terminal 607 and the origin signal terminal 609 are sent to a controller (not shown). The controller counts the rotational position of the motor from the output of the pulse extraction terminal 607 and detects the origin position from the output from the origin signal terminal 609.

BS is a data bus, and the encoder unit 300 and the speed control unit 4
00 to transmit signals between the position control unit 500 and the tuning unit 600.

Here, when the load inertia J of the motor is unknown, the switch 502 is connected to the contact k ₂ side and a known test signal is given to the position control means 505. At this time, the signal output from the position control unit 500 is output to the motor. Monitor using the terminal. And
Adjust the load inertia setting value with the inertia setting switch so that the distortion of the monitor waveform is eliminated.

The setting of _Fn and J may be performed by an external controller instead of using the switches.

Moreover, the case has been described where the control parameters are read out when both the natural frequency f _n and the load inertia J is set by a servo tuning switch from the gain table 506 in the embodiment, one of the f _n and J is not limited thereto The control parameter may be read when is set.

[Effects] According to the present invention, the encoder code plate is provided with two stages of translucent slits, and the difference in the number of translucent slits in each of the outer and inner translucent slits is determined by the teeth of the motor portion. It is the same as the number. Therefore, the phase difference between the detection signal of the light passing through the light transmitting slits in the outer light transmitting slit row and the detection signal of the light passing through the light transmitting slits in the inner light transmitting slit row is It becomes the phase shift of the teeth of the stator itself. The commutation control of the motor can be performed based on this phase shift. The phase difference described above is measured by a phase difference counter. Therefore, a signal used for commutation control of the motor can be obtained from the phase difference measured by the phase difference counter.

In addition, by measuring the cycle of the detection signal of the image sensor with a cycle counter, measuring how much the cycle of the detection signal deviates from the cycle when the motor is stopped at regular intervals, and adding up the measured values. The rotational position of the motor is detected. The detected rotational position is used for position feedback control of the motor.

Further, the rotation speed of the motor is detected based on the frequency of the detection signal of the image sensor given to the encoder I / F. The detected rotation speed is used for speed feedback control of the motor.

From the above, according to the present invention, one encoder I /
At F, signals used for motor commutation control, position control, and speed control are obtained at the same time. As a result, the position control, speed control and commutation control of the motor can be performed with a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a DD motor system according to the present invention, FIG. 2 is a diagram showing a specific configuration example of FIG. 1, and FIG. 3 is a diagram showing a specific configuration example of a motor section. FIG. 4 is a diagram showing a specific configuration example of the current detection circuit of the drive circuit, and FIGS.
FIG. 7 is an operation explanatory diagram of the circuit of FIG. 4, FIGS. 8 to 10 are diagrams showing a specific configuration example of the encoder section, FIG. 11 is an operation explanatory diagram of the encoder I / F, and FIG. FIG. 6 is a diagram showing an example of a gain table stored in a position control unit. 100 …… Motor part, 300 …… Encoder part, 300 ₁ …… Encoder, 300 ₂ …… Encoder I / F, 301 …… Code plate, 302,
303 …… Transparent slit, 304,305 …… Light source, 308,309 ……
Image sensor, 317, 318 Cycle counter, 319 Phase difference counter, 400 Speed controller, 500 Position controller, 507 Commutation control means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Morimoto 2-932 Nakamachi, Musashino City, Tokyo Yokogawa Electric Co., Ltd. (72) Hideo Manshi Hideo Mansai 2-932 Nakamachi, Musashino City, Tokyo Horizontal Kawa Electric Co., Ltd. (72) Inventor Yasuhiko Muramatsu 2-9-32 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd. (72) Inventor Shotaro Shindo 2-9-32 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Within the corporation

Claims (1)

[Claims] 1. A direct drive type motor section in which a rotor is arranged on the outside and a stator is arranged on the inside, an encoder section which detects the rotation of the motor section and outputs a detection signal, and a detection signal of the encoder section. A speed control unit that feedback-controls the rotation speed of the motor unit based on the following: a position control unit that feedback-controls the rotation position of the motor unit based on the detection signal of the encoder unit; and a detection signal of the encoder unit. Commutation control means for controlling commutation of the motor section based on the above, the encoder section is composed of an encoder and an encoder interface, and the encoder is an optical rotary encoder having two stages. A transparent slit row is provided, and the difference in the number of transparent slits on the outer and inner transparent slit rows is The number of teeth is the same as the number of teeth, light sources for projecting light to the light-transmitting slits in the two-stage light-transmitting slit rows, and photodiodes arranged in an array. The encoder interface has an image sensor for detecting light passing through each of the light-transmitting slits in the light slit row, and the encoder interface has a cycle counter for counting a cycle of a detection signal of the image sensor and an outer light-transmitting slit row. There is a phase difference counter that counts the phase difference between the detection signal of the image sensor that detects the light passing through a certain light-transmitting slit and the detection signal of the image sensor that detects the light passing through the light-transmitting slit in the inner light-transmitting slit row. Then, based on the cycle counted by the cycle counter, a signal used for position control of the motor unit is calculated based on the frequency of the detection signal of the image sensor. Direct drive motor system, characterized in that to obtain a signal to be used for speed control of the motor unit, a signal used for commutation control of motor based on the phase difference counted by the phase difference counter, respectively.