JP6966142B1 - Rotary encoder and servo control device using it - Google Patents

Abstract

When the motor performs high-precision position accuracy in the low-speed rotation range, the problem that the motor does not follow the control signal at the time of high-speed rotation is solved. The rotary encoder includes a magnetic sensor unit, a high-precision incremental signal generation unit, a motor control signal generation unit, and a resolution switching control unit, and the phase information included in the low-precision incremental signal of the magnetic sensor unit and the magnetic sensor unit. Low speed and high speed based on the function to generate a high precision incremental signal (mechanical angle) based on the angle information contained in the high precision absolute signal, and the low precision incremental signal and the high precision incremental signal. A function to generate an accurate motor control signal (electric angle), a function to generate a high-speed and low-precision motor control signal (electric angle) based on the low-precision incremental signal and the high-precision incremental signal, and a function to generate a high-speed and low-precision motor control signal (electric angle). It has a function of outputting the low-speed and high-precision motor control signal when the motor is rotating at low speed, and outputting the high-speed and low-precision motor control signal when the motor is rotating at high speed.

Description

The present invention relates to a rotary encoder that outputs motor rotation / angle information as a digital signal to the outside, and a servo control device using the rotary encoder. In particular, the present invention relates to a resolution switching type rotary encoder that generates resolution information suitable for motor control according to the rotation speed of the motor, and a servo control device using the same.

Servo control device As the rotary encoder used, various types are known depending on the type and application of the motor.

Patent Document 1 discloses a servomotor control device capable of controlling a motor with high accuracy based on an output signal of a rotary encoder by using one rotation sensor unit including an MR sensor and a Hall element and a brushless DC servomotor. Has been done. In such a servomotor control device, there is a problem that the motor does not follow a highly accurate control signal at high speed rotation.

In Patent Document 2, in a servo system in which a resolver is connected, the resolution of the RD converter is switched based on the motor speed, the resolution is set low when the motor speed exceeds a certain level, the responsiveness is improved, and the motor speed is constant. If the following is true, the invention is disclosed in which the resolution is set high and the positioning accuracy is improved.
Patent Document 3 discloses a detection device that switches a detection mode between a low-speed mode and a high-speed mode in a rotary encoder.

Japanese Patent No. 6339307 Special Table 2010-63218 JP-A-2017-227457

The resolver and RD converter described in Patent Document 2 have a complicated structure and are expensive as compared with a rotary encoder using an MR sensor.
The rotary encoder described in Patent Document 3 intermittently drives a sensor element in order to reduce power consumption, and is not suitable for a servo control device such as a robot.

One of the problems of the present invention is to have a function of solving the problem that the motor does not follow the control signal at high speed rotation while performing high precision position accuracy in the low speed rotation range, regardless of the type and application of the motor. It is an object of the present invention to provide a versatile and inexpensive rotary encoder that can meet various needs, and a servo control device using the rotary encoder.

According to one aspect of the present invention, the rotary encoder includes a magnetic sensor unit that outputs information on the rotation angle of the rotation shaft of the motor, and outputs information on the rotation / angle of the motor to the outside as a digital signal.
The magnetic sensor unit has a function of outputting a low-precision incremental signal and a high-precision absolute signal as mechanical angle information with respect to the phase and rotation angle of the rotation axis of the motor.
The rotary encoder includes a high-precision incremental signal generation unit, a motor control signal generation unit, and a resolution switching control unit.
The high-precision incremental signal generation unit generates a high-precision mechanical angle incremental signal based on the phase information included in the low-precision incremental signal and the rotation angle information included in the high-precision absolute signal. Has the ability to generate
The motor control signal generation unit is a low-precision, high-precision electrical angle incremental motor control signal based on the low-precision incremental signal, the high-precision incremental signal, and preset specifications of the motor. A low-speed, high-precision control signal generator that generates
A high-speed, low-precision incremental motor control signal that generates a high-speed, low-precision electrical angle incremental motor control signal based on the low-precision incremental signal, the high-precision incremental signal, and preset specifications of the motor. Equipped with a control signal generator
The resolution switching control unit outputs an incremental motor control signal of the low speed and high precision electric angle when the motor is rotating at a low speed, and when the motor is rotating at a high speed, the incremental motor of the high speed and low precision electric angle. It is characterized in that it is configured to output a motor control signal.

According to another aspect of the present invention, the servo control device includes the rotary encoder and a motor having a motor driver.
The motor driver generates an incremental motor drive signal from the motor control signal output from the rotary encoder to drive the motor.

According to the present invention, while providing a function of solving the problem that the motor does not follow the control signal at the time of high-speed rotation while performing high-precision position accuracy in the low-speed rotation range, various types are provided regardless of the type and application of the motor. It is possible to provide a rotary encoder which is rich in versatility and inexpensive and can meet the needs of the above, and a servo control device using the rotary encoder.

It is a figure which shows the structural example of the servo control apparatus provided with the resolution switching type rotary encoder which concerns on 1st Embodiment of this invention. It is a vertical cross-sectional view which shows the structural example of the main part of the DC motor with a brush which constitutes the servo control device of FIG. It is a figure which shows the structural example of the magnetic sensor unit in 1st Example. It is a figure which shows the structural example of the rotary encoder in 1st Example. It is a figure which shows a part of the process flow of the rotary encoder in 1st Example. It is a figure which shows an example of the processing in the MR sensor and the rotary encoder in 1st Example. It is a figure which shows an example of the operation pattern of the servo control device when the rotary encoder of 1st Example is mounted on a robot. It is a figure which shows an example of the processing flow of the rotary encoder in 1st Example. It is a figure which shows the specific example of the switching of the resolution of a motor control signal in 1st Example. It is a figure which shows an example of the pattern (electrical angle) of a motor control signal in 1st Example. It is a figure which shows the structural example of the brushless DC servomotor which concerns on 2nd Example of this invention. It is a figure which shows an example of the processing flow of the rotary encoder in 2nd Example. It is a figure which shows an example of the pattern (electrical angle) of a motor control signal in 2nd Example. It is a figure which shows the structural example of the stepping servomotor which concerns on 3rd Example of this invention. It is a figure which shows an example of the processing flow of the rotary encoder in the 3rd Example.

The present invention is applicable to various types of motors, but the first embodiment is an example of applying the present invention to a brushed DC motor. A servo control device including the resolution switching type rotary encoder according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 8B.
FIG. 1 is a diagram showing a configuration example of a resolution switching type servo control device 10 according to a first embodiment of the present invention.
The servo control device 10 includes a rotary encoder 100 and a motor 500. The rotary encoder 100 is integrally provided with the motor 500, generates two systems of high-precision and low-precision incremental motor control signals based on the rotation information of the motor 500, and outputs them as digital signals to the motor driver 510.
The rotary encoder 100 includes one magnetic sensor unit 110, an initial setting unit 120, a high-precision incremental signal generation unit 130, a motor control signal generation unit 140, a resolution switching control unit 150, a communication control unit 160, and a non-volatile memory 170. Etc. are provided. The rotary encoder 100 and the motor driver 510 are provided with a predetermined controlled power source from the power source via a power supply line (not shown).
The magnetic sensor unit 110 includes, for example, a magnetic sensor such as a magnetoresistive effect element or a Hall element, and outputs information on the rotation / angle (mechanical angle) of the rotation axis of the motor 500 as an incremental signal or an absolute signal.
The initial setting unit 120 has a function of accepting initial settings such as output conditions of the rotary encoder 100 by the user via the user interface. The user can perform initial setting of the rotary encoder 100 according to the specifications of the motor of the motor 500 to which the rotary encoder 100 is mounted, that is, the type and specifications of the motor, and the application. The initial setting conditions are recorded in the non-volatile memory 170. For example, at the time of initial setting, the following conditions are set in the rotary encoder 100.
(1) Specifications of the motor to be driven (type, number of poles, number of slots, etc.)
(2) Output conditions (pulse / rotation) of high-precision signal and low-precision signal of incremental signal
(3) Precision switching rotation speed Ns of the motor that switches between high-precision signals and low-precision signals
The user interface can be realized by installing a dedicated application that executes a program having a predetermined function on a smartphone or tablet terminal.

The high-precision incremental signal generation unit 130 has a function of generating a set of high-precision incremental signals (mechanical angle) based on a set of absolute / incremental signals of the magnetic sensor unit 110.

The motor control signal generation unit 140 is a motor control signal (an incremental A, B, Z signal, an A, B, Z, U, V, W signal, etc., depending on the type of motor, the number of poles, the number of slots, etc. Electric angle) is generated and output. That is, the motor control signal generation unit 140 generates an incremental motor control signal (electric angle) in a wide range from low-speed operation to high-speed operation of the motor based on the low-precision incremental signal and the high-precision incremental signal. This motor control signal is used in the motor driver 510 to generate a drive signal such as PWM.

The resolution switching control unit 150 outputs one of two high-precision and low-precision motor control signals (electrical angles) output from the rotary encoder 100 to the motor driver 510. The resolution switching control unit 150 also predicts the timing of switching between the two high-precision and low-precision motor control signals from the change in the rotation speed N of the motor, and controls the switching of the motor control signals.
That is, the resolution switching control unit 150 acquires the data of the rotation speed N of the motor and predicts the timing of switching the resolution based on the comparison with the preset accuracy switching rotation speed Ns of the motor. When the motor rotates at a low speed of Ns or less, a high-precision incremental control signal with high resolution is generated, recorded in the non-volatile memory 170, and output to the motor driver. Further, when the motor rotates at a speed higher than Ns, a low-precision incremental control signal having a low resolution is generated, recorded in the non-volatile memory 170, and output to the motor driver. Then, when the motor reaches the precision switching rotation speed Ns and further shifts to high-speed rotation or low-speed rotation, control of switching of the control signal is performed.

The communication control unit 160 has a function of transmitting various information from the rotary encoder 100 to the motor driver 510.

The motor 500 includes a PWM drive circuit that constitutes the motor driver 510, and an H-bridge circuit in which four switching elements SW1 to SW4 composed of transistors are assembled in an H shape. One end of the first switching element SW1 is connected to one brush 565A of the DC motor and the other end is connected to the DC power supply (Vcc), and one end of the second switching element SW2 is connected to the other brush 565B of the DC motor. It is connected and the other end is connected to a DC power supply (Vcc). One end of the third switching element SW3 is connected to one brush 565A of the DC motor and the other end is grounded, and one end of the fourth switching element SW4 is connected to the other brush 565B of the DC motor and the other end is grounded. Has been done.

The motor driver 510 is provided with a memory or the like for recording an operation command, and is a motor drive signal synchronized with the period (that is, the phase of the A, B, Z signals) of the motor control signal (electrical angle) output from the rotary encoder 100. Therefore, the ON duty in each cycle generates a PWM drive signal controlled based on an operation command, a load current value of the motor, and the like. The PWM circuit is driven by this motor drive signal, and the motor 500 rotates. Based on the motor control signal from the rotary encoder 100, the motor driver 510 generates a motor drive signal with high accuracy when the motor is rotating at a low speed and low accuracy when the motor is rotating at a high speed, and outputs the motor drive signal to the motor driver. Needless to say, the motor drive signal generated by the motor driver 510 may be a known signal other than the PWM method.

The initial setting unit 120, the high-precision incremental signal generation unit 130, the motor control signal generation unit 140, the resolution switching control unit 150, and the communication control unit 160 shown in the form of functional blocks in FIG. 1 have, for example, predetermined functions. It is composed of an FPGA (Field Programmable Gate Array) 180 and a microcomputer (Microcontroller Unit) that are realized by executing a program. The microcomputer and FPGA are composed of an I / O unit, internal wiring, a logic circuit, a clock network, a memory, a multiplier and the like. Programs and the like that form the basis of logic circuits are recorded in an external EEPROM or memory.
The specific internal configuration of the FPGA 180 can be flexibly changed by changing the description of the program or the like. Therefore, by assuming a wide range of initial settings in advance according to the type and application of the motor and enriching the functions of each unit, various needs can be met regardless of the type and application of the motor. I can respond.
The main part of the rotary encoder 100 may be configured by an ASIC (Application Specific Integrated Circuit) instead of the microcomputer or FPGA.

FIG. 2 is a vertical cross-sectional view showing a configuration example of a main part of the brushed DC motor 500 to which the rotary encoder 100 of FIG. 1 is mounted. In this example, an MR sensor is used as the magnetoresistive element of the magnetic sensor unit 110. A circular flat plate magnet 1110 is fixed to one end surface of the rotating shaft 532 of the brushed DC motor 500 via a magnet holder. A driven member is fixed to the other end of the rotating shaft 532.
A magnet 526 that constitutes a stator of a DC motor is fixed to the motor case 520. A laminated iron core 560 and an armature winding 562 constituting a rotor of a DC motor are integrally formed with a rotating shaft 532, and the rotating shaft is rotatably supported by a motor case 520 and an end plate 521 via a bearing 530. There is. The laminated iron core 560 is multi-pole polarized, and the end of the armature winding 562 is connected to the commutator 564. 565 is a pair of carbon brushes, 566 is a brush holder, 567 is a pigtail, and 568 is a terminal for power supply.

On the other hand, inside the cup-shaped cover-522, a substrate 190 made of an insulating material on which the rotary encoder 100 is mounted is fixed to the end plate 521 via a support pin 192. A pair of MR sensors 1122 (1122A, 1122B), a microcomputer, an FPGA, and the like are installed on the substrate 190. As the MR sensor 1122, any element of a magnetoresistive element (MR: AMR, GMR, TMR, etc.) including GMR may be adopted.

FIG. 3A is a diagram showing a configuration example of the magnetic sensor unit 110 in the first embodiment. The magnetic sensor unit 110 includes a pair of MR sensors 1122, a temperature sensor 1122C, and a sensor output processing circuit unit 1120. The sensor output processing circuit unit 1120 is roughly divided into an incremental signal processing area 1121 that performs incremental signal generation processing and an absolute signal processing area 1130 that performs absolute signal generation processing.
The sensor output processing circuit unit 1120 has two signals, an incremental signal with low accuracy (for example, 4K pulse / rotation) and an absolute signal with high accuracy (for example, 32K pulse / rotation) with respect to the rotation / angle of the rotation axis of the motor. It has a function to output.
The incremental signal processing area 1121 includes an AD converter 1123, an axis misalignment correction processing unit 1124, a sensor memory 1125 such as a RAM, an inverse tangent calculation processing unit 1126, a pulse counter 1127, an incremental signal generation unit 1128, and an SSC (synchronous serial control). It has an interface 1129. This SSC interface uses data, clock, and frame sync signals for transmission and reception for high-speed data transfer.
In this incremental signal processing area 1121, the digital signals of the A phase and the B phase are synchronized with the position of the angle 0 (= 360 degrees) for each rotation of the rotation axis as a result of the inverse tangent calculation by parallel processing, and 4K. A right-angled triangular signal is generated in which the incremental value of pulse / rotation repeats increasing and decreasing linearly. Then, the cumulative addition value of each A-phase / B-phase signal is then converted into a cumulative addition value for each rotation of the rotation axis (every 360 degrees), and the low-precision, that is, 4K pulse / rotation incremental signal is a digital signal. (See FIG. 5 left side (A)).

Further, the absolute signal processing area 1130 includes an SSC-SPI (Serial Peripheral Interface) bus conversion unit 1132, an absolute signal (high precision) generation unit 1134, and an EEPROM 1136. In the absolute signal processing area 1130, the incremental value of 44K pulse / rotation is further divided into 32K pulse / rotation by digital processing, and the address of the EEPROM based on the origin Z0 of the rotation axis is assigned to this, that is, high accuracy. A 32K pulse / rotation absolute signal is generated as a 15-bit digital signal (see FIG. 5, left side (B)).

In the magnetic sensor unit 110, the function of the incremental signal processing area 1121 and the function of the absolute signal processing area 1130 that performs the absolute signal generation processing are configured as described above, so that the sensor output processing circuit unit 1120 can be used. Both the incremental signal and the absolute signal required for motor control can be generated and output. In addition to this, in order to generate a high-precision incremental absolute signal in the magnetic sensor unit 110, an expensive microcomputer or FPGA having high-performance arithmetic processing capability is required, and the price of the rotary encoder is high. It is not practical.

FIG. 3B is a diagram showing a specific configuration example of the motor control signal generation unit 140 and the resolution switching control unit 150 in the rotary encoder 100 of FIG.
The motor control signal generation unit 140 includes a low-speed / high-precision control signal generation unit 142 that generates a low-speed / high-precision incremental motor control signal, and a high-speed / low-precision motor control signal that generates a high-speed / low-precision incremental motor control signal. The control signal generation unit 144 of the above is provided.
That is, in the motor control signal generation unit 140, the motor control signal of the motor is based on the low-precision incremental signal output from the magnetic sensor unit 110 and the high-precision incremental signal output from the high-precision incremental signal generation unit 130. Generates absolute signals (electrical angles) with different accuracy corresponding to low-speed operation and high-speed operation. This motor control signal is used by the motor driver 510 to generate a motor drive signal such as PWM.

The resolution switching control unit 150 includes a shaft rotation speed / rotation direction detection unit 152, a switching time prediction unit 154, and a resolution switching control unit 156.
The rotation number / rotation direction detection unit 152 of the shaft acquires data of the rotation direction and rotation number N of the rotation shaft 532 based on the output of the magnetic sensor unit 110, and the switching time prediction unit 154 sets the rotation number N in advance. Based on the comparison with the set precision switching rotation speed Ns of the motor, the switching time and switching direction (from high precision to low precision or from low precision to high precision) of the resolution are predicted. The resolution switching control unit 156 generates a signal after switching based on prediction, and outputs a signal with resolution after switching at the time of switching. In this way, the resolution switching control unit 150 controls so that the accuracy of the incremental drive signal of the motor is smoothly switched when the rotation speed of the motor changes from low speed to high speed or in the opposite direction.

FIG. 4 is a diagram showing a part of the processing flow of the high-precision incremental signal generation unit 130 of the rotary encoder 100 in the first embodiment.
First, the initial setting conditions related to the functions of the rotary encoder 100, which are preset in the initial settings, are acquired (S400). Here, it is assumed that the high-precision signal is set to the incremental signal of 32K pulse / rotation, and the low-precision signal is set to the incremental signal of 4K pulse / rotation. First, based on the signal from the magnetic sensor unit, information on the rotation speed N and the rotation direction of the motor is acquired and recorded in the non-volatile memory (S401). Next, a low-precision incremental signal is acquired from the magnetic sensor unit and recorded in the memory (S402). Further, a high-precision absolute signal is acquired and recorded in the memory (S406).
Next, the high-precision incremental signal generation unit 130 generates an incremental signal of 32 K pulse / rotation from the phase information of the incremental signal and the angle information of the absolute signal, and records the incremental signal in the non-volatile memory (S408).

Here, with reference to FIG. 5, the relationship between the output of the magnetic sensor unit 110 and the output of the high-precision incremental signal generation unit 130 in S402 to S408 of FIG. 4 will be described in more detail.
Based on the phase information contained in the low-precision incremental signal (left side (A) of FIG. 5) generated by the magnetic sensor unit 110 and the angle information included in the high-precision absolute signal (left side (B) of FIG. 5). The high-precision incremental signal generation unit 130 of the rotary encoder 100 generates a high-precision incremental signal (right side (B) in FIG. 5).
The motor control signal generation unit 140 includes a low-precision incremental signal (FIG. 5 left side (A) = right side (A)) generated by the magnetic sensor unit 110 and a high-precision incremental signal (FIG. 5 right side (B)). Two sets of motor control signals (electrical angles) are generated based on.

Next, FIG. 6 is a diagram showing an example of an operation pattern of a motor 500 for driving a drive shaft 810 of a certain arm of a robot 800 equipped with a rotary encoder 100. In this example, data on the relationship between the time axis (= axis rotation angle) and the speed value of the motor is preset as the operation pattern of the motor that drives the axes of the arms constituting the robot.
The drive shaft 810 of the arm is repeatedly driven in the forward rotation and the reverse rotation in excess of the accuracy switching rotation speed Ns. When the robot moves between a plurality of points, it is desirable that the robot moves at a high speed, and when working at a specific point, the drive shaft of the arm is preferably stopped or driven at a low speed. Position control when moving at high speed may be performed with low accuracy. On the other hand, when working at a specific point, highly accurate positioning is required.
In order to meet these demands, the rotary encoder 100 of the present invention generates and outputs a high-precision motor control signal at low speed and a low-precision motor control signal at high speed.

FIG. 7 is a diagram showing a processing flow of the rotary encoder 100 in the first embodiment.
First, information on the specifications of the brushed DC motor is acquired from the initial setting information (S702). Here, it is assumed that the precision switching rotation speed Ns is set to ± 40 rpm. After starting from zero rotation of the motor, information on the rotation speed N and rotation direction of the motor is acquired from the non-volatile memory (S710), and the low-speed, high-precision control signal generation unit 142 of the motor control signal generation unit 140 Generates high-precision incremental control signals A, B, Z of 32K pulse / rotation.
That is, the motor control signals A, B, Z (electrical angles) of the pattern shown in FIG. 8B generated by the low-speed and high-precision control signal generation unit 142 are sent to the motor driver 510 as 32K digital signals. It is output (S712).
Further, the resolution switching control unit 150 acquires information on the rotation speed N and the rotation direction of the motor (S714), and predicts the switching time point when the rotation speed N of the motor exceeds the precision switching rotation speed Ns (S716).
If it is determined that the switching time is near (YES in S718), for example, it is a command that the difference between the motor rotation speed and the accuracy switching rotation speed Ns is within 20 rpm and the rotation speed increases toward the switching time. In this case, the resolution switching control unit 156 enters the "control switching preparation" mode (S724).

FIG. 8A is a diagram showing a specific example of precision switching of the motor control signal. When the motor rotation speed N is in the vicinity of the precision switching rotation speed Ns, here ± 40 rpm, the resolution switching control unit 156 is in the “control switching preparation” mode, and the motor control signal generation unit 140 is operated at low speed and with high accuracy. Both the control signal generation unit 142 and the high-speed / low-precision control signal generation unit 144 are activated, and both a low-precision incremental control signal of 4K pulse / rotation and a high-precision incremental control signal of 32K pulse / rotation are generated. NS.
When the motor rotation speed N is within ± 40 rpm, the switching control unit 156 outputs a high-precision motor control signal to the motor driver 510, and the motor driver uses this high-precision motor control signal as a basis for high-precision motor control signals. A PWM signal is generated.

Returning to FIG. 7, when the switching time is reached (YES in S726), the switching control unit 156 outputs a low-precision motor control signal to the motor driver 510 to control the motor and a high-precision motor control signal. The output is stopped (S728).
That is, the motor control signals A, B, Z (electrical angles) of the pattern shown in FIG. 8B generated by the high-speed and low-precision control signal generation unit 144 are sent to the motor driver 510 as 4K digital signals. It is output. In the motor driver, a low-precision PWM signal is generated based on this low-precision motor control signal.
When the rotation speed of the motor becomes higher, the "control switching preparation" mode is canceled, and the generation of the high-precision motor control signal by the low-speed / high-precision control signal generation unit 142 is stopped.
Similarly, for switching from the low-precision motor control signal to the high-precision motor control signal, control is performed via the "control switching preparation" mode (S730 to S738 to S712).
If the switching time is not near (NO in S718), it is determined whether or not the operation is finished, and if not, the process returns to S714. If it ends, the operation is stopped (S720, S722).

As described above, according to the present embodiment, the motor is controlled by the high-precision incremental drive signal in the low-speed rotation range, and the motor is controlled by the low-precision incremental drive signal in the high-speed range. It is possible to solve the problem that the motor does not follow the control signal at high speed rotation while performing position accuracy.
Further, the rotary encoder of this embodiment, as a magnetic sensor unit, outputs information on the rotation and angle of the rotation shaft of the motor as two sets of mechanical angle signals, an incremental signal and an absolute signal, which have different accuracy. It uses one expensive and inexpensive magnetic sensor unit. Further, the rotary encoder has an initial setting function. Therefore, regarding an incremental type brushed DC motor, it is possible to provide a small, versatile, inexpensive rotary encoder that can meet various needs, and a servo control device using the rotary encoder.
Further, in the motor driver, a PWM signal can be generated based on the motor control signal from the rotary encoder, so that the configuration of the motor driver is simplified.

Next, a second embodiment in which the present invention is applied to a brushless DC motor will be described with reference to FIGS. 9 to 10B.
FIG. 9 is a diagram showing a configuration example of the brushless DC servomotor according to the second embodiment.
This brushless DC servomotor includes a rotary encoder 100 having the same configuration as that described in the first embodiment, and a brushless DC motor 500.
The brushless DC motor 500 includes a field iron core 541 and a three-phase field coil 542 wound around the field iron core 541 as a stator fixed inside the motor case 520. In this field coil 542, the field coils of the U phase (U1, U2, U3) are in series, and the field coils of the V phase (V1, V2, V3) are in series, and the W phase (W1, W2, W3). ) Coil is connected in series. One end of each of these three field coil groups is connected at a neutral point.
The rotor 543 integrally formed with the rotating shaft 532 is an 8-pole rotor having a rotor yoke and, for example, eight permanent magnets fixed to the outer peripheral portion thereof.
The motor driver of the brushless DC motor is a three-phase incremental motor based on the motor control signals A, B, Z, U, V, W from the rotary encoder 100, the operation command, the detected value of the motor current, and the like. A drive signal is generated to drive the inverter, and the brushless DC motor 500 is operated, for example, a sinusoidal drive.

Next, FIG. 10A is a diagram showing a processing flow of the rotary encoder 100 in the second embodiment.
The rotary encoder 100 first acquires information on the specifications of the brushed DC motor from the initial setting information (S1002). After starting from zero rotation of the motor, information on the rotation speed N and rotation direction of the motor is acquired from the non-volatile memory (S1010), and is generated by the low-speed, high-precision control signal generation unit 142 of the motor control signal generation unit 140. The 32K pulse / rotation high-precision incremental control signals A, B, Z, U, V, and W are output to the motor driver (S1012).
That is, the motor control signals A, B, Z, U, V, W (electrical angles) having the pattern shown in FIG. 10B are generated as 32K digital signals by the low-speed, high-precision control signal generation unit 142. , Is output to the motor driver 510 (S1012). In the motor driver, a high-precision PWM signal is generated based on this high-precision motor control signal.

Further, the resolution switching control unit 150 acquires information on the motor rotation speed N and the rotation direction (S1014), predicts the switching time point when the motor rotation speed N exceeds the accuracy switching rotation speed Ns (S1016), and predicts the switching time point. When is close (YES in S1018), the high-speed and low-precision control signal generator 144 also operates, and when the switching time is reached (YES in S1026), a low-precision motor control signal is output to the motor driver to output the motor. While controlling, the output of the high-precision motor control signal is stopped (S1028). That is, the motor control signals A, B, Z, U, V, W (electrical angles) of the pattern shown in FIG. 10B generated by the high-speed and low-precision control signal generation unit 144 are 4K digital signals. Is output to the motor driver 510 (S1028). In the motor driver, a low-precision PWM signal is generated based on this low-precision motor control signal.
Similarly, for switching from the low-precision motor control signal to the high-precision motor control signal, control is performed via the "control switching preparation" mode (S103 to S1038 to S1012).

In this way, when the motor rotation speed N is low speed, for example, within ± 40 rpm, the switching control unit 156 outputs high-precision motor control signals A, B, Z, U, V, and W to the motor driver, and the motor. The driver generates a highly accurate PWM signal as a motor drive signal based on the motor control signal. When the motor rotation speed N exceeds ± 40 rpm, the switching control unit 156 outputs a low-precision motor control signal to the motor driver, and the motor driver uses this low-precision motor control signal as a motor drive signal. Low-precision PWM signal is generated.

According to the servomotor using the brushless DC motor of this embodiment, the rotary encoder outputs a high-precision control signal in the low-speed range to control the brushless DC motor, and outputs a low-precision control signal in the high-speed range. Controls the brushless DC motor. Therefore, it is possible to solve the problem that the motor does not follow the control signal at the time of high-speed rotation while performing high-precision position accuracy in the low-speed rotation range.
Further, the rotary encoder of this embodiment, as a magnetic sensor unit, outputs information on the rotation and angle of the rotation shaft of the motor as two sets of mechanical angle signals, an incremental signal and an absolute signal, which have different accuracy. It uses one expensive and inexpensive magnetic sensor unit. Further, the rotary encoder has an initial setting function. Therefore, regarding an incremental type brushless DC motor, it is possible to provide a small, versatile, inexpensive rotary encoder that can meet various needs, and a servo control device using the rotary encoder.
Further, in the motor driver, a PWM signal can be generated based on the motor control signal from the rotary encoder, so that the configuration of the motor driver is simplified.

FIG. 11 is a diagram showing a configuration example of a stepping servomotor according to a third embodiment of the present invention. This stepping servomotor includes a rotary encoder 100 and a motor 500 having the same configuration as that described in the first embodiment.
The motor 500 has, for example, a rotor magnet 520 having two poles and a stator having four stator coils at 90 degree intervals. The stator 558 of the motor 500 has a stator coil A + 5583 having a function of concentrating and discharging magnetic fields generated at both ends of the A-phase coil 5581, and magnetic fields generated at both ends of the stator coils A-5584 and the B-phase coil 5582. The stator coil B + 5585 and the stator coil B-5586, which have a function of concentrating and discharging the magnet coil B + 5585, are provided.
One flat magnet 1110 is fixed to one end of the rotating shaft 532 of the rotor magnet of the motor 500. The flat magnet 1110 constitutes a part of the magnetic sensor unit 110. The specific configuration of the magnetic sensor unit and the rotary encoder 100 is the same as the configuration of the first embodiment.

The motor driver 510 includes a PWM drive circuit that generates a drive waveform for the motor, and is based on the motor control signal (electrical angle), the operation command, the detected value of the motor current, etc., which are the outputs of the rotary encoder 100, and the motor. A drive signal is generated to control the rotation of the rotor magnet of the motor 500.
That is, the motor control signal, which is the output of the rotary encoder 100, is sent to the driver 510, where a PWM command value corresponding to the phase information of the incremental signal is generated, and the stepping motor 500 receives the PWM command value. A voltage is applied to the A-phase coil 5581 and the B-phase coil 5582, whereby the rotor magnet 520 rotates.

With the activation of the stepping servomotor, the low-speed, high-precision control signal generation unit 142 of the motor control signal generation unit 140 is activated, and an incremental motor control signal of 32 K pulse / rotation is generated. In the stepping motor 500, a motor drive signal is generated based on the motor drive signal, an operation command, and the like, and a voltage is applied to the A-phase stator coil and the B-phase stator coil of the stepping motor via the PWM drive circuit. This causes the rotor magnet 520 to rotate.

When the motor is rotating at a low speed, a high-precision motor control signal is output to the motor driver, and a high-precision PWM signal as a motor drive signal is generated. When the motor rotation speed N exceeds the precision switching rotation speed Ns, a low-precision motor control signal is output to the motor driver, and a low-precision PWM signal is generated based on the low-precision motor control signal.

According to the stepping servomotor of this embodiment, the rotary encoder outputs a high-precision motor control signal in the low-speed range to control the motor, and outputs a low-precision motor control signal in the high-speed range to control the motor. .. Therefore, it is possible to solve the problem that the motor does not follow the control signal at the time of high-speed rotation while performing high-precision position accuracy in the low-speed rotation range.
Further, the rotary encoder of this embodiment, as a magnetic sensor unit, outputs information on the rotation and angle of the rotation shaft of the motor as two sets of mechanical angle signals, an incremental signal and an absolute signal, which have different accuracy. It uses one expensive and inexpensive magnetic sensor unit. Further, the rotary encoder has an initial setting function. Therefore, regarding an incremental type stepping motor, it is possible to provide a small, versatile, inexpensive rotary encoder that can meet various needs, and a stepping servo device using the rotary encoder. Further, in the motor driver, a PWM signal can be generated based on the motor control signal from the rotary encoder, so that the configuration of the motor driver is simplified.

As another embodiment of the present invention, the motor control signal generation unit of the rotary encoder in Examples 1 to 3 may be configured as a motor control signal generation unit that generates two sets of absolute signals having different accuracy. good. That is, the rotary encoder includes a low-precision absolute signal generation unit, which is based on the angle information included in the low-precision incremental signal generated by the magnetic sensor unit and the phase information contained in the high-precision absolute signal. , Generates a low precision absolute signal. The motor control signal generation unit is based on two sets of absolute signals having different accuracy, and has a wide range of high-precision and low-precision motor control signals (electrical angles) from low-speed operation to high-speed operation of the motor. ) Is generated. This makes it possible to provide a rotary encoder capable of appropriately controlling an absolute compatible motor from low speed to high speed.

The present invention can be applied to various motors other than the types of motors described in the above examples. For example, it can be widely applied to various motors such as synchronous motors and induction motors. It can also be applied to a servo control device using these motors.

10 Servo control device 100 Rotary encoder 110 Magnetic sensor unit 1110 Flat plate magnet 1122 MR sensor 130 High-precision incremental signal generation unit 140 Motor control signal generation unit 142 Low-speed / high-precision control signal generation unit 144 High-speed / low-precision control signal generation Unit 150 Resolution switching control unit 170 Non-volatile memory 180 FPGA
190 Board 500 Motor 510 Motor driver 532 Motor rotation shaft 520 Motor case 530 Bearing

Claims (7)

A rotary encoder equipped with a magnetic sensor unit that outputs information on the rotation angle of the rotation axis of the motor, and outputs information on the rotation and angle of the motor to the outside as a digital signal.
The magnetic sensor unit has a function of outputting a low-precision incremental signal and a high-precision absolute signal as mechanical angle information with respect to the phase and rotation angle of the rotation axis of the motor.
The rotary encoder includes a high-precision incremental signal generation unit, a motor control signal generation unit, and a resolution switching control unit.
The high-precision incremental signal generation unit generates a high-precision mechanical angle incremental signal based on the phase information included in the low-precision incremental signal and the rotation angle information included in the high-precision absolute signal. Has the ability to generate
The motor control signal generation unit is
A low-speed, high-precision incremental motor control signal that generates a low-speed, high-precision electrical angle incremental motor control signal based on the low-precision incremental signal, the high-precision incremental signal, and preset specifications of the motor. Control signal generator and
A high-speed, low-precision incremental motor control signal that generates a high-speed, low-precision electrical angle incremental motor control signal based on the low-precision incremental signal, the high-precision incremental signal, and preset specifications of the motor. Equipped with a control signal generator
The resolution switching control unit outputs an incremental motor control signal of the low speed and high precision electric angle when the motor is rotating at a low speed, and when the motor is rotating at a high speed, the incremental motor of the high speed and low precision electric angle. A rotary encoder characterized in that it is configured to output a motor control signal. In claim 1,
The rotary encoder, wherein the high-precision incremental signal generation unit, the motor control signal generation unit, and the resolution switching control unit are composed of a microcomputer, an FPGA, or an ASIC. In claim 1,
The rotary encoder is provided with an initial setting unit.
The rotary encoder is characterized in that the initial setting unit has a function of receiving information on the specifications of the motor and the accuracy switching rotation speed Ns of the motor for switching the accuracy of the motor control signal as initial settings. In claim 3,
The motor control signal generation unit is one of a brushed DC motor, a brushless DC motor, and a stepping motor based on the low-precision incremental signal and the high-precision incremental signal based on the initial setting conditions. A rotary encoder characterized in that it is configured to be able to generate a motor control signal corresponding to the above. In claim 3,
The resolution switching control unit acquires the rotation speed N of the motor, and predicts the switching time point at which the rotation speed of the motor exceeds the precision switching rotation speed Ns from the operation command to the motor and the rotation speed N of the motor. Then, when it is determined that the switching time is near, the mode shifts to the control switching preparation mode, and both the low-speed / high-precision control signal generation unit and the high-speed / low-precision control signal generation unit are activated. A rotary encoder characterized in that it is configured to generate both a low-precision incremental control signal and the high-precision incremental control signal. The rotary encoder according to claim 1 and
A servo control device including a motor having a motor driver.
A resolution switching type servo control device characterized in that an incremental motor drive signal is generated by the motor driver from the motor control signal output from the rotary encoder to drive the motor. In claim 6,
The rotary encoder is provided with an initial setting unit.
The initial setting unit has a function of receiving information on the type and specifications of the motor to which the rotary encoder is mounted and the accuracy switching rotation speed Ns of the motor that switches the accuracy of the motor control signal as initial settings. Ori,
The resolution switching control unit acquires the rotation speed N of the motor, and predicts the switching time point at which the rotation speed of the motor exceeds the precision switching rotation speed Ns from the operation command and the rotation speed N of the motor. When it is determined that the switching time is near, the mode shifts to the control switching preparation mode.
The motor control signal generation unit simultaneously generates the high-precision signal and the low-precision signal in the switching preparation mode, and when the switching time is reached, the output of the motor control signal is set to the rotation speed N of the motor. A resolution switching type servo control device characterized by switching to a corresponding resolution.

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