TWI849769B - Magnetic rotary encoder and backup control method thereof - Google Patents

Abstract

A magnetic rotary encoder is provided, which can generate relatively high-precision rotation angle information as position information for backup control when the first magnetic sensor fails, while utilizing the output signal of a second magnetic sensor that is less accurate and inexpensive than the first magnetic sensor. The magnetic rotary encoder comprises: a first magnetic sensor signal processing unit, which generates first analog data and first digital data related to the rotation angle of the rotary shaft according to the output of the first magnetic sensor; and a second magnetic sensor signal processing unit, which generates second analog data and second digital data related to the rotary shaft according to analog-to-digital (AD) conversion data of the output of the second magnetic sensor. The resolution of the second magnetic sensor is worse than that of the first magnetic sensor. The output of the second magnetic sensor is corrected according to the output of the first magnetic sensor. As the fail-safe function of the rotary encoder, the second analog data and the second digital data of the second magnetic sensor are corrected according to the calibration history of the second magnetic sensor.

Description

Magnetic rotary encoder and backup control method thereof

The present invention relates to a magnetic rotary encoder and a backup control method thereof, and to a magnetic rotary encoder having a backup function when a magnetic sensor fails or power is lost, and a backup control method thereof.

A rotary encoder is used to detect the angular position and rotational speed of a rotating shaft driven by a rotary motor. In particular, in the case of a motor such as a brushless DC motor, an absolute digital signal or an incremental digital signal related to the angular position is generated and output according to the angular position or rotational speed of the rotating shaft detected by a magnetic sensor, and these signals are used to control the motor as a servo motor. For rotary encoders used in industrial robots and other machines where system redundancy is important, a backup control function (fail-safe function) using other normal magnetic sensors is given so that the machine can continue to operate safely even if the rotary encoder fails during operation.

The rotation angle detection device disclosed in Patent Document 1 has three or more rotation angle sensors and a rotation angle derivation unit. The rotation angle sensors use magnetic detection elements such as MR elements or Hall elements as magnetic flux detection units. The rotation angle derivation unit calculates the rotation angle of the output shaft based on the rotation of the rotation angle sensors other than the rotation angle sensors determined to be abnormal.

Patent document 2 discloses the following invention: In a rotation angle detection device of a motor having a GMR sensor and an AMR sensor, the output of the AMR sensor is generally used to correct the output of the GMR sensor and obtain the mechanical angle θ. In the event of a GMR sensor failure, the output of the AMR sensor is used alone to detect the mechanical angle θ and perform backup control. The microcomputer has a counter. When it is determined that the output of the GMR sensor is offset corrected, the count value is first recorded as 1 in the counter. When the GMR sensor fails, the output value of the AMR sensor is offset corrected based on this count value.

The encoder with an optical or magnetic angle detection unit disclosed in Patent Document 3 includes: a primary battery such as a battery, a button cell, a dry cell, and a rechargeable secondary battery. In addition, the following invention is disclosed: the secondary battery is charged by an electrical signal generating unit using a magnetically sensitive metal wire such as a Wiegand metal wire, and even when the main power of the device equipped with the encoder device is not turned on (emergency state, backup state), at least a part of the rotation position information of the rotating shaft (such as multi-rotation information) can still be detected.

Prior art literature Patent Literature

Patent document 1: Japanese Patent Publication No. 2022-164402

Patent document 2: Japanese Patent Publication No. 2022-105702

Patent document 3: Japanese Patent Publication No. 2016-109554

The invention of Patent Document 1 can calculate the rotation angle of the output shaft only based on the rotation of other normal rotation angle sensors when one rotation angle sensor of the rotation angle detection device has been judged to be abnormal. Therefore, various industrial machines controlled by this rotation angle detection device have the advantage of being able to continue to operate safely even if one rotation angle sensor is abnormal. On the other hand, in the invention of Patent Document 1, sensors of the same type and characteristics must be used as three or more rotation angle sensors, and when high-precision rotation angle sensors are used, there is a possibility of an overall cost increase. Depending on the use of various industrial machines, there are also areas where backup control must be performed using a rotation angle sensor that is cheaper and less prone to failure.

In the invention of Patent Document 2, since the GMR sensor and the AMR sensor are arranged at an interval of 180 degrees, the output of the GMR sensor and the output of the AMR sensor will be offset. Therefore, when the GMR sensor fails, the output value of the AMR sensor is offset based on this count value. However, this offset is caused by the special structure of the GMR sensor and the AMR sensor being arranged at an interval of 180 degrees. In addition, Patent Document 2 does not record the content of correction other than the above offset correction when the GMR sensor fails.

In the invention of Patent Document 3, the power supply system is equipped with a power switch (power selection unit, selection unit), which is configured to switch (select) which of the primary battery and the secondary battery is used to supply power to the position detection system, and the secondary battery is charged by the electrical signal generating unit. However, when the power switch fails, there is a possibility that power cannot be properly supplied to the position detection system.

One of the topics of the present invention is to provide a magnetic rotary encoder and a backup control method thereof. Generally, the output signal of the first magnetic sensor is used to generate high-precision rotation angle information. As the position information for backup control when the first magnetic sensor fails, the output signal of the second magnetic sensor with lower accuracy and lower price than the first magnetic sensor can be used to generate relatively high-precision rotation angle information.

Another subject of the present invention is to provide a magnetic rotary encoder, which has a backup control function. The backup control function is to properly record the information of the rotation angle of the motor's rotating shaft, so that the necessary information can be properly provided when the motor is started next time.

According to one aspect of the present invention, a rotary encoder comprises: a magnet fixed to a rotating shaft; a first magnetic sensor signal processing unit, which performs analog-to-digital (AD) conversion on a first analog signal outputted by a first magnetic sensor disposed opposite to the magnet, and generates first digital data related to a rotation angle and a rotation direction of the rotating shaft based on the analog-to-digital conversion data of the output of the first magnetic sensor, wherein the first digital data includes information of two systems, namely, an absolute signal and an incremental signal; and a second The magnetic sensor signal processing unit performs analog-to-digital conversion on the output of the second magnetic sensor disposed opposite to the magnet, that is, the second analog signal, and generates second digital data related to the rotation angle and the rotation direction of the rotation axis based on the analog-to-digital conversion data of the output of the second magnetic sensor. The second digital data includes information of two systems, namely, an absolute signal and an incremental signal. The resolution of the second magnetic sensor is lower than that of the first magnetic sensor. The second magnetic sensor signal The processing unit of the first magnetic sensor signal has a fail-safe function of backing up the processing unit of the first magnetic sensor signal, and the processing unit of the second magnetic sensor signal has the following functions: based on the data of the first analog signal of the first magnetic sensor, correct the second analog signal of the second magnetic sensor and perform the analog-to-digital conversion, and correct the analog-to-digital conversion data output by the second magnetic sensor based on the first digital data of the first magnetic sensor to generate the first analog signal of the second magnetic sensor. 2 digital data, and record the calibration history of the aforementioned second analog signal and the calibration history of the aforementioned second digital data. The aforementioned fail-safe function of the aforementioned rotary encoder is constituted as follows: when the aforementioned first magnetic sensor and/or the aforementioned first magnetic sensor signal processing unit fails, the aforementioned second analog signal of the aforementioned second magnetic sensor is calibrated according to the calibration history of the aforementioned second analog signal, and the aforementioned second digital data of the aforementioned second magnetic sensor is calibrated according to the calibration history of the aforementioned second digital data.

According to one aspect of the present invention, a rotary encoder can be provided, which can generate position information with relatively high accuracy by using a second magnetic sensor which is less accurate than the first magnetic sensor but is inexpensive, and can perform backup control with high reliability.

According to another aspect of the present invention, the first magnetic sensor is arranged on the printed circuit board at a position corresponding to the axis of the rotating shaft, the second magnetic sensor is arranged on the same plane as the first magnetic sensor on the printed circuit board at intervals of 120 degrees on a circle centered on the axis of the rotating shaft, and a temperature sensor is arranged on the printed circuit board.

The rotary encoder has a main power source whose output voltage is controlled to a predetermined power, a Barkhausen effect power source, and an auxiliary battery as a power source unit. The Barkhausen effect power source and the auxiliary battery are power sources for backup when the main power source is lost. The Barkhausen effect power source has a Barkhausen effect element. The Barkhausen effect element is arranged on the printed circuit board to be located on the back side of the first magnetic sensor and generates electricity using the rotating magnetic field of the magnet. The auxiliary battery has a capacitor charged by the main power source and the Barkhausen effect power source.

According to this aspect, a magnetic rotary encoder with a backup control function can be provided. The backup control function is to appropriately record the rotation angle information of the motor's rotating shaft when either the first magnetic sensor or the second magnetic sensor fails, and further when there is a power outage, so that necessary information can be appropriately provided when the motor is started next time.

According to another aspect of the present invention, the first analog signal, the second analog signal, the first digital data, and the second digital data are monitored. In the monitoring results of the above-mentioned data, when it is determined that the above-mentioned first magnetic sensor or the processing unit of the above-mentioned first magnetic sensor signal is abnormal, in the processing unit of the above-mentioned second magnetic sensor signal, a calibrated analog signal is generated according to the above-mentioned second analog signal of the above-mentioned second magnetic sensor, and the calibrated second digital data is generated according to the above-mentioned calibrated analog signal and the calibration data of the above-mentioned second digital data.

According to this aspect, even in the event of a failure of the aforementioned first magnetic sensor, highly reliable backup control can still be performed.

10: Rotary encoder

11: Magnetic sensor unit

110: Magnet

111: Magnetic sensor No. 1

1111,1112: Magnetic sensor

112: Second magnetic sensor

113: Temperature sensor

115: Barkhausen effect power generation unit

12: Power unit

121: Main power supply

1211: Main power supply unit

122: Barkhausen effect power source

1221,1231:Diode

1222: Full-wave waveform circuit

1223: Smoothing circuit

123: Auxiliary battery

1230: Components

1232: Current limiting circuit

1233:Capacitor

1234: Voltage limiting circuit

1235: PWM control unit

1236:MOSFET

1237:Resistance

124: Output terminal

13: Temperature sensor

130: Encoder output control unit

14: System control unit

141: Initial settings section

142: Setting Department

143: Data for fault safety control

144: Encoder input and output control unit

145: Fail-safe control unit

146: Output switching unit

147: Serial/parallel signal sending and receiving unit

15: Processing unit for the first magnetic sensor signal

151: Analog signal (sin, cos), amplitude detection unit of the first magnetic sensor

152:Analog-to-digital converter

1521:ADC-1(sin)

1522:ADC-2(cos)

1523:EEPROM-1

153: Digital signal processing department

1531: Digital signal, frequency/rotation direction detection unit of the first magnetic sensor

1532: Absolute signal generating unit of the first magnetic sensor

1533: Incremental A, B, Z, (U, V, W) signal generation unit of the first magnetic sensor

16: Second magnetic sensor signal processing unit

160: Analog signal processing unit

161: Distortion correction, amplitude and synchronization correction unit of the analog signal of the second magnetic sensor

162:Analog-to-digital converter

1621:ADC-3

1622:ADC-4

1623:ADC-5

1624:EEPROM-5

163: Digital signal processing department

1631: Digital signal detection and frequency/rotation direction correction unit of the second magnetic sensor

1632: Absolute signal generating unit of the second magnetic sensor

1633: Incremental A, B, Z, (U, V, W) signal generation unit of the second magnetic sensor

164: Failure safety, signal correction department

165:EEPROM-4

166:EEPROM-6

17: Printed circuit board

18:FPGA

40: Servo control device

50: Motor

510: Rotation axis

H1, H2, H3: Hall element

O-O: axis (axis)

S700,S701,S702,S703,S704,S711,S721,S722,S731,S732,S733,S734,S740,S741,S900,S901,S902,S903,S904,S911,S921,S922,S931,S932,S9 33, S934,S940,S942,S1000,S1001,S1002,S1003,S1004,S1005,S1006,S1007,S1010,S1011,S1012,S1013,S1014, S1020,S1021,S1022,S1023,S1024,S1030,S1031,S1032,S1101,S1102,S1103,S1104,S1105,S1106,S1107,S1108,S1109,S1110,S1111,S1112,S1113,S1114,S1124,S1201,S1202, S1203, S1204, S1205, S1206, S1207, S1208, S1209, S1210, S1211, S1212, S1213: Steps

t0,t1,t2,t3,t4,t5: time

Vcc: voltage

Φa,Φb: magnetic flux

FIG1 is a functional block diagram showing an example of the configuration of a rotary encoder of the first embodiment of the present invention.

FIG2 is a diagram showing an example of the configuration of a servo control system having a rotary encoder according to the first embodiment.

FIG3 is a longitudinal cross-sectional view showing an example of the configuration of a magnetic sensor and a power supply unit in the rotary encoder of the first embodiment.

FIG4 is a diagram showing an example of the circuit configuration of the power supply unit in the first embodiment.

FIG5 is a timing diagram showing the operation of the power supply unit, and is a diagram showing an example of the relationship between the power supply and the output signal of the rotary encoder when the power supply of the main power supply changes from a normal state to a power outage.

FIG6 is a diagram showing another example of the circuit configuration of the power supply unit.

Figure 7 is a diagram showing the digitization and absolute processing of the first magnetic sensor signal.

FIG8 is a flow chart showing the signal processing in the processing unit of the first magnetic sensor signal in the first embodiment.

FIG9 is a diagram showing an example of the A-phase and B-phase signals processed according to the signal in FIG8 and the incremental Z-phase, U-phase, V-phase, and W-phase signals generated according to these signals.

Figure 10 is a diagram showing the digitization and absolute processing of the second magnetic sensor signal.

FIG11 is a flow chart showing the signal processing in the processing unit of the second magnetic sensor signal in the first embodiment.

FIG12 is a flowchart showing the processing of the fail-safe control unit in the first embodiment.

FIG13 is a flow chart showing the data processing of the processing unit of the second magnetic sensor signal during normal operation.

FIG14 is a flow chart showing the data processing of the processing unit of the second magnetic sensor signal in the fail-safe mode.

The form used to implement the invention

The first embodiment of the present invention is described below with reference to the drawings.

First, the overall structure and function of the rotary encoder of the first embodiment of the present invention will be described with reference to Figures 1 to 3.

FIG1 is a functional block diagram showing an example of the configuration of a rotary encoder, and FIG2 is a diagram showing an example of the configuration of a servo control system having the rotary encoder.

The rotary encoder 10 has a magnetic sensor unit 11, a power supply unit 12, a temperature sensor 13, a system control unit 14, a first magnetic sensor signal processing unit 15, and a second magnetic sensor signal processing unit 16.

The rotary encoder 10 is further provided with a flat magnet 110 with each pole magnetized to N and S. This flat magnet is, for example, a ferromagnetic magnet, and is fixed to one end surface of the rotating shaft 510 of the motor 50 as shown in FIG3 . In addition, a rare earth magnet such as a neodymium magnet or a samarium cobalt magnet may be used to replace the ferromagnetic magnet.

The magnetic sensor unit 11 includes a first magnetic sensor 111 and a second magnetic sensor 112, and the first magnetic sensor 111 includes a temperature sensor 113.

The first magnetic sensor 111 is composed of a pair of magnetic sensors (Sin, Cos) and is arranged at a position facing the magnet 110 in the axial direction of the rotating shaft 510. That is, the first magnetic sensor 111 is arranged on the printed circuit board 17 at a position corresponding to the axis O-O of the rotating shaft 510.

The first magnetic sensor 111 used in the present invention is a sensor that can obtain a high-precision resolution. The second magnetic sensor is preferably a magnetic sensor that has a simpler structure and is less prone to failure, although its resolution is inferior to that of the first magnetic sensor.

In the first embodiment, a TMR sensor is used as the first magnetic sensor 111, and three Hall elements (H1, H2, H3) arranged at 120 degree intervals are used as the second magnetic sensor 112. The Hall element is a GaAs element, for example. In addition, the TMR sensor has a built-in temperature sensor, and its output is a temperature-compensated output.

The power supply unit 12 includes a main power supply 121, a Barkhausen effect power supply 122, and an auxiliary battery 123. The Barkhausen effect power supply 122 and the auxiliary battery 123 function as power supplies for supplying electric power to the rotary encoder 10 when the power supply of the main power supply is lost. A Barkhausen effect power supply unit 115 is provided near the magnet 110. The Barkhausen effect power supply unit 115 is fixed to a position on the back side of the first magnetic sensor 111 on the printed circuit board 17 (refer to FIG. 3). The Barkhausen effect power supply unit 115 has a composite magnetic wire and a coil. The composite magnetic wire is centered on the axis O-O and is arranged in a direction orthogonal to the axis. The Barkhausen effect power generation unit 115 generates power generated by the Barkhausen effect along with the rotation of the rotating shaft 510 and the magnetic flux Φb of the flat magnet 110, and supplies the output to the Barkhausen effect power source 122.

The system control unit 14 has the following functions: when the first magnetic sensor 111 and the first magnetic sensor signal processing unit 15 function normally, the information of the first magnetic sensor signal processing unit 15 is output as the output of the rotary encoder 10; when the first magnetic sensor 111 and the first magnetic sensor signal processing unit 15 are abnormal, the information of the second magnetic sensor signal processing unit 16 is output as the output of the rotary encoder 10.

The initial setting section 141 of the system control unit 14 has a setting section 142 and a holding function of the fail-safe control data 143. The setting section 142 sets the type of motor, pole number, origin of the rotation axis or output conditions of the rotary encoder according to the conditions input through the user interface. The fail-safe control data 143 includes data related to trigonometric functions or data related to linear functions for data correction, for example. The data related to trigonometric functions is used to correct the analog output of the second magnetic sensor based on the analog output of the first magnetic sensor, and the data related to the linear function is used to correct the digital output of the second magnetic sensor based on the digital output of the first magnetic sensor.

The encoder input/output control unit 144 has the function of controlling the input/output of the rotary encoder 10 according to the conditions of the initial setting. The fail-safe control unit 145 controls the fail-safe mode executed when the magnetic sensor or the like fails. The output switching unit 146 has the function of switching the output of the rotary encoder in response to the operating state of the rotary encoder. The serial/parallel signal transmission and reception unit 147 has the function of converting various information into parallel signals or serial signals and transmitting and receiving between the rotary encoder 10 and the servo control device 40.

The rotary encoder 10 of the present invention can be applied to various rotary motors that require absolute data and incremental data of A, B, and Z.

The following is a more detailed description of the application of the present invention to the structure of a rotary encoder targeting a brushless DC motor.

The first magnetic sensor signal processing unit 15 performs analog-to-digital conversion on the output of the first magnetic sensor disposed opposite to the magnet 110, that is, the first analog signal, and generates first digital data related to the rotation angle and rotation direction of the rotating shaft based on the analog-to-digital conversion data of the output of the first magnetic sensor. That is, the first magnetic sensor signal processing unit 15 has the following functions: with respect to the rotation angle information of the rotating shaft, it generates two systems of information, namely, an absolute signal and an incremental signal of a high resolution (for example, 27 bits/rotation) quantized by the analog output of the first magnetic sensor 111 under predetermined conditions, as the first digital data in a highly accurate manner. From the rotary encoder, as the first digital data, such as incremental A, B, Z, (U, V, W) signals will be converted into transmission data (BUS) for serial transmission and sent to the servo control device via the communication cable.

Furthermore, the second magnetic sensor signal processing unit 16 performs analog-to-digital conversion on the output of the second magnetic sensor arranged relative to the magnet 110, i.e., the second analog signal, and generates second digital data related to the rotation angle and rotation direction of the aforementioned rotating shaft based on the analog-to-digital conversion data of the output of the aforementioned second magnetic sensor. That is, the second magnetic sensor signal processing unit 16 has the following functions: with respect to the rotation angle information of the rotation axis, generate two systems of information of an absolute signal and an incremental signal with a relatively high resolution (for example, 21 bits/rotation) as the second digital data in a highly accurate manner. The relatively high resolution information is based on the correction process of the signal generated by the first magnetic sensor signal processing unit to correct the analog output of the second magnetic sensor 112 and quantize the information with predetermined conditions.

The first magnetic sensor signal processing unit 15 has a first analog signal processing unit, i.e., an analog signal (sin, cos), an amplitude detection unit 151, an analog-to-digital converter 152, and a digital signal processing unit 153.

The analog signal (sin, cos) and amplitude detection unit 151 receives the sampled data of the first analog signal (sin signal, cos signal) of the first magnetic sensor 111 as time series data, calculates the number of rotations, and temporarily records the rotation angle (mechanical angle) of these analog signals in the memory by establishing a relationship with the amplitude of the analog signal, the number of rotations Nx of the rotating shaft, and the data of the temperature sensor 13. At the same time, the sampled data of the analog signal of the first magnetic sensor 111 is input to, for example, a 64-bit analog-to-digital converter 152 (ADC-1 (sin) 1521, ADC-2 (cos) 1522) and converted into digital values, and these converted values are recorded in EEPROM-1 (1523) as time series data.

The absolute signal generating unit 1532 of the first magnetic sensor of the digital signal processing unit 153 obtains the analog-to-digital conversion data of the rotating shaft from EEPROM-1 to generate an absolute signal of the rotation angle of the rotating shaft and records it in EEPROM-2 as time series data.

Furthermore, the digital signal of the first magnetic sensor, the frequency/rotation direction detection unit 1531 obtains the digital value from EEPROM-1, calculates its frequency, and records the frequency and the rotation direction data together in EEPROM-2.

On the other hand, the incremental A, B, Z, (U, V, W) signal generating unit 1533 of the first magnetic sensor obtains the digital value of the absolute signal of the rotation angle of the rotation axis from EEPROM-2 as the first digital data, generates incremental A, B, Z, (U, V, W) signals, and records them as time series data in EEPROM-3.

The second magnetic sensor signal processing unit 16 includes an analog signal processing unit 160, an analog-to-digital converter 162, and a digital signal processing unit 163.

The distortion correction, amplitude and synchronization correction unit 161 of the analog signal of the second magnetic sensor receives the sampling data of the second analog signal (sin signal of H1, sin signal of H2, sin signal of H3) of the second magnetic sensor 112 as time series data, and performs distortion correction corresponding to the eccentricity of the axis O-O of each Hall element (H1, H2, H3), calculates the number of rotations, and records it in the memory.

On the other hand, the analog signal (sin, cos) of the first magnetic sensor signal processing unit 15 and the amplitude detection unit 151 are used to obtain the rotation angle (mechanical angle) of the first analog signal of the first magnetic sensor 111, the amplitude of the analog signal, the number of rotations Nx, and the data of the temperature sensor 13. Furthermore, these data are related and temporarily recorded in the memory.

In addition, based on the rotation angle (mechanical angle) and amplitude of the first analog signal, the number of rotations Nx, and the data of the temperature sensor 13, the data of each rotation of the second analog signal of the second magnetic sensor 112 is subjected to amplitude correction and synchronization correction, that is, the data is corrected, and the corrected analog data and the correction history are recorded in EEPROM-4 (165).

In addition, regarding the second analog signal, although it is also possible to perform amplitude correction and synchronization correction on each signal corresponding to each Hall element (H1, H2, H3) and the first analog signal individually, in order to speed up the processing, it is desirable to perform amplitude correction and synchronization correction at one time.

Furthermore, as long as the approximate expression of the trigonometric function that has been related to the data of the temperature sensor 13 is used in the correction of the data of the second analog signal, it is not necessary to calibrate the data for each rotation, but it can be performed in a predetermined angle range or sampling unit. That is, the data of the second analog signal of the second magnetic sensor 112 at any rotation angle can be directly corrected based on the data of the first analog signal of the first magnetic sensor 111, and the first magnetic sensor 111 is located in a corresponding positional relationship based on the data of the relationship between the pre-set approximate expression of the trigonometric function and the temperature sensor 13.

The calibrated analog data is input to, for example, a 64-bit analog-to-digital converter 162 (ADC-3~5 (1621-1623)) and converted into digital values. The converted values are recorded in EEPROM-5 (1624) as time series data.

In the "fail-safe mode" when the first magnetic sensor 111 or the first magnetic sensor signal processing unit 15 fails, the fail-safe signal correction unit 164 performs amplitude and synchronization correction of the second analog signal of the second magnetic sensor according to the correction process recorded in the EEPROM-4 (165), and records the result as corrected analog data in the EEPROM-4 (165).

The absolute signal generating unit 1632 of the second magnetic sensor of the digital signal processing unit 163 obtains the data of the analog-to-digital conversion of the rotating shaft from the EEPROM-5 every time the rotating shaft rotates one circle, generates an absolute signal of the rotation angle of the rotating shaft, and records it in the memory as a time series of (tentative) absolute data. This (tentative) absolute data is corrected in the digital signal detection and frequency/rotation direction correction unit 1631 of the second magnetic sensor. That is, the digital signal detection and frequency/rotation direction correction unit 1631 of the second magnetic sensor obtains the frequency/rotation direction data of the digital signal of each rotation of the first magnetic sensor generated by the digital signal and frequency/rotation direction detection unit 1531 of the first magnetic sensor, synchronizes the absolute data of the time series of the second magnetic sensor, corrects the rotation direction, and records the result as the second digital data, that is, as the (formal) absolute data of the second magnetic sensor in EEPROM-7. In addition, the correction process of the absolute data is recorded in EEPROM-6 (166).

In addition, as long as the linear function approximation is used for data correction, it is not necessary to perform data correction for each rotation, but it can be performed within a predetermined angle range. That is, the second digital data of the second magnetic sensor 112 at any rotation angle can be corrected based on the first digital data of the first magnetic sensor 111, and the first magnetic sensor 111 is located in a corresponding position relationship based on the pre-set linear function approximation and the data of the temperature sensor 13.

On the other hand, the incremental A, B, Z, (U, V, W) signal generating unit 1633 of the second magnetic sensor obtains the digital value of the absolute signal of the rotation angle of the calibrated rotation axis from EEPROM-7, generates incremental A, B, Z, (U, V, W) signals, and records them as time series data in EEPROM-8.

In "fail-safe mode", the frequency/rotation direction correction of the absolute data of the second magnetic sensor is performed based on the correction process of the absolute data recorded in EEPROM-6 for the analog-to-digital conversion data of each rotation of the rotating shaft obtained from EEPROM-5, and the result is recorded in EEPROM-6 as the calibrated digital value and correction process.

In addition, each functional block shown in FIG1 is a functional block shown as an example. The division of each functional block is arbitrary, and of course, a common program can be used to implement the above-mentioned multiple functional blocks, or a different multiple program or IC circuit can be used to implement a specific functional block.

Alternatively, the above functions can be realized by assembling a program for executing the above functions in a microcomputer equipped with a CPU or memory.

As shown in FIG2 , the rotary encoder 10, the servo control device 40, and the motor 50 together form a servo control system.

Most of the rotary encoder 10, that is, the portion other than the flat magnet 110 of the magnetic sensor unit 11, the power unit 12, the temperature sensor 13, the system control unit 14, the first magnetic sensor signal processing unit 15, and the second magnetic sensor signal processing unit 16 are formed or assembled on a printed circuit board 17. This printed circuit board is fixed to the housing of the motor 50 (omitted in the figure).

In particular, the system control unit 14, the first magnetic sensor signal processing unit 15, and the second magnetic sensor signal processing unit 16 are implemented by a dedicated FPGA 18 (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit), or an IC circuit chip using a general-purpose single-chip microcomputer, and are formed on a printed circuit board 17.

In addition, the system control unit 14, the first magnetic sensor signal processing unit 15, and the second magnetic sensor signal processing unit 16 are functionally divided blocks, and these functions are implemented by describing the program in the digital signal processing unit of FPGA or ASIC, SSC interface, incremental interface, etc.

In addition, the FPGA includes ROM, RAM, and at least one rewritable (overwritten) non-volatile memory, and is connected to the CPU via a bus. Moreover, as a rewritable (overwritten) non-volatile memory, EEPROM or FRAM (Ferroelectric Random Access Memory, (registered trademark)) can be used. In the following description, such a memory is simply recorded as EEPROM.

A pair of magnetoresistance elements constituting the first magnetic sensor 111 are arranged at predetermined intervals in the rotation direction of the rotating shaft in such a way that the phases of the analog signals outputted are staggered by 90 degrees. As the first magnetic sensor 111, a TMR (Tunnel magnetoresistance effect) element can be used. The first magnetic sensor 111 senses the magnetic flux Φa of the flat magnet 110 as the rotating shaft 510 rotates and outputs a sine wave and a cosine wave.

In addition, the position of one end of the boundary line between the N-pole region and the S-pole region of the magnet 110 is a specific position in the circumferential direction on the rotation axis, that is, the origin position (Z ₀ ) corresponding to the rising time point of the A-phase pulse.

The three Hall elements of the second magnetic sensor 112 are arranged on the printed circuit board 17 at equal intervals outside the radial direction of the first magnetic sensor 111. A Hall IC can also be used to replace the Hall element. In the following, the Hall element or the Hall IC is simply recorded as "Hall element".

Next, the circuit configuration example of the power supply unit in the first embodiment will be described with reference to FIG. 4.

The main power supply 121 of the power supply unit 12 has a main power supply unit 1211, which converts the power supplied from the commercial power supply into a DC power supply and controls it at a predetermined DC voltage Vcc, such as 5V. This main power supply unit 1211 supplies power to the output terminal 124 via a diode 1221.

The Barkhausen effect power source 122 outputs a positive and negative pulse waveform at intervals of 180 degrees for each rotation of the rotating shaft from the Barkhausen effect power generation unit 115. This power is passed through the full-wave waveform circuit 1222, the smoothing circuit 1223, and the diode 1231, and the DC power of the predetermined voltage Vcc is supplied to the output terminal 124.

The auxiliary battery 123 has a current limiting circuit 1232, a capacitor 1233, and a voltage limiting circuit 1234, and supplies a DC power of a predetermined voltage Vcc to the output terminal 124. The capacitor 1233 is supplied with power from both the main power source 121 and the Barkhausen effect power generation power source 122. When the power of the main power source is lost and the rotating shaft stops rotating, the capacitor 1233 functions as a power source for supplying power to the rotary encoder 10. The current limiting circuit 1232 is controlled to: when the motor rotation speed is high and the amount of electricity generated by the Barkhausen effect power generation unit 115 is large, the current supplied to the capacitor 1233 is limited so that the charge within the allowable range is accumulated in the capacitor 1233. For example, a double-layer capacitor can be used as the capacitor 1233. In order to alleviate the voltage drop, multiple capacitors can also be connected in parallel to form the capacitor 1233.

The power line connected to the output terminal 124 of the power unit 12 is a line that constitutes three electrically independent systems, and supplies power to the system control unit 14, the first magnetic sensor signal processing unit 15, the second magnetic sensor signal processing unit 16, and each sensor of the magnetic sensor unit 11.

FIG5 is a timing diagram showing the operation of the power supply unit, and is a diagram showing an example of the relationship between the power supply and the output signal of the rotary encoder when the power supply of the main power supply changes from a normal state to a power outage.

When the main power source 1211 of the main power source fails to supply power at time t1, for example, due to a power outage or a fault, power is supplied to the rotary encoder 10 from the Barkhausen effect power source 122 that generates power accompanying the rotation of the rotating shaft.

After a power outage, when the number of rotations of the rotating shaft decreases over time, the output of the Barkhausen effect power generation will decrease, and it will become impossible to supply the DC power of the predetermined voltage Vcc at time t2. When this state is reached, the power of the voltage Vcc is supplied to the rotary encoder 10 by the charge accumulated in the capacitor 1233 of the auxiliary battery 123.

Thus, the rotary encoder 10 can generate and record the information of the rotation angle of the rotating shaft for a long time, for example, before the moment t3 when the rotation of the rotating shaft completely stops.

In addition, when the rotating shaft stops due to a power outage, if the rotating shaft is forcibly rotated by an external force such as human power through a robot arm, the output of the Barkhausen effect power generation and the charge accumulated in the capacitor 1233 will supply power to the rotary encoder 10 between time t4 and t5. Therefore, when the rotating shaft stops due to a power outage and is rotated by an external force, the information of the rotation angle of the rotating shaft is also recorded.

Next, FIG. 6 is a diagram showing another example of the circuit configuration of the power supply unit. Instead of the current limiting circuit 1232 of FIG. 4, a MOSFET 1236 controlled by a PWM control unit 1235 is used to perform PWM control on the current supplied from the Barkhausen effect power generation unit 115 to the capacitor 1233. Symbol 1237 is a resistor for current detection. The capacitor 1233 is supplied with power from both the main power supply 121 and the Barkhausen effect power generation power supply 122 individually. In this example, the PWM control of the MOSFET 1236 is performed in response to the detection value of the charging voltage or current of the capacitor 1233, and the charge accumulated in the capacitor 1233 is controlled to be the optimal value.

In this example, the rotary encoder 10 can also generate and record the information of the rotation angle of the rotating shaft for a long time, such as before the rotation of the rotating shaft stops or before it is driven by an external force.

Next, the digitization and absolute processing of the first magnetic sensor signal in the first magnetic sensor signal processing unit 15 will be described with reference to Figures 7, 8, and 9.

The first magnetic sensor signal processing unit 15 obtains information about the pole number of the motor and the origin of the rotation axis from the initial setting value (S701).

As shown in (A) of FIG7 , the first magnetic sensor (TMR sensor) 111 outputs 360 degrees (mechanical angle) and the first analog signal of each cycle as a SIN wave and a COS wave for each rotation of the rotating shaft. The data of the rotation angle (mechanical angle) and amplitude, and the number of rotations Nx of these first analog signals are recorded in the memory by establishing a relationship between the analog signal (sin, cos) of the first magnetic sensor signal processing unit 15, the amplitude detection unit 151, and the temperature Ta of the temperature sensor 13. Generally speaking, since the Hall element and the TMR sensor are more easily affected by the temperature of the gas environment, such processing is required.

Here, assuming that the first analog signal output from the first magnetic sensor (TMR sensor) is a correct sine wave, if the displacement y1 (i.e., amplitude) at time t and position x is set to y1(x, t), then y1(x, t) is expressed by the following formula.

y1(x,t)=Asin2π(t/T-x/λ) (1)

Among them, T is the period, λ is the wavelength, and A is a constant.

The actual analog signal output from the first magnetic sensor has been temperature compensated and can be considered to be approximately equal to the above equation (1).

Therefore, the trigonometric function approximation y1(x, t, Ta) of the SIN wave and COS wave of the actual analog signal output by the first magnetic sensor in relation to the temperature Ta of the substrate can be obtained in advance and retained as initial setting data. The approximation of this trigonometric function can be used to generate data on the rotation angle (mechanical angle) and amplitude of the first analog signal, as well as the number of rotations Nx. In this way, highly accurate calibration data for the second analog signal can be generated over a wide range from the low-speed rotation area to the high-speed rotation area.

As shown in (B) of FIG. 7 , the analog signal (sin signal, cos signal) is input to the analog-to-digital converter 152, quantized and converted into a multi-divided digital signal by interpolation processing, and converted into a digital value containing information of phase A and phase B. These conversion values are related to the number of rotations Nx and the temperature Ta and recorded in EEPROM-1.

As shown in the flowchart of FIG8 , the first magnetic sensor signal processing unit 15 obtains the analog-to-digital conversion data of the first magnetic sensor signal (Sin, Cos wave) from EEPROM-1 (S702). The first magnetic sensor signal processing unit 15 further interpolates the digital waveform according to the analog-to-digital conversion data of the first analog signal (sin signal, cos signal) by time division, etc., and changes it to display the absolute position from the origin, such as the data of the rotation angle of 27 bits, and calculates it as an absolute value (S703). Then, the absolute value is addressed to the memory and recorded in the memory (S704).

That is, as shown in FIG7 (C), the frequency/rotation direction detection unit 1531 calculates the frequency of each forward and reverse rotation of the rotating shaft according to the digital value of EEPROM-1 through the digital signal of the first magnetic sensor, generates an absolute value for each forward and reverse rotation, and records it in EEPROM-2 together with the number of rotations Nx, temperature Ta, and rotation direction data.

Here, assuming that the first analog signal output from the first magnetic sensor is a correct sine wave, if the absolute value obtained from the digital value of EEPROM-1 is set to y2(x, t), then y2(x, t) can be expressed as a linear function related to the temperature Ta.

That is, the absolute value shown in FIG. 7(C) based on the actual analog signal output from the first magnetic sensor can also be approximated by the above-mentioned linear function. Therefore, the approximate formula of the absolute value of the SIN wave and COS wave based on the actual analog signal output from the first magnetic sensor can be obtained in advance according to the temperature Ta, and first maintained as the initial setting data. The approximate formula of the absolute value can be used to generate the absolute value for each forward and reverse rotation. In this way, calibration data with high-precision absolute data can be generated over a wide range from the low-speed rotation area to the high-speed rotation area.

In addition, in the digital signal and frequency/rotation direction detection unit 1531 of the first magnetic sensor, multi-rotation information including rotation direction, rotation angle, and rotation number is generated from the origin information and the absolute value and recorded in EEPROM-2 (S711).

The absolute signal generating unit 1532 of the first magnetic sensor calculates the number of rotations from the origin information and the absolute value (S721), generates multi-rotation absolute information, and records it in EEPROM-2 as multi-rotation absolute data (S722).

Furthermore, the incremental A, B, Z, (U, V, W) signal generating unit 1533 of the first magnetic sensor calculates the data of phase A and phase B from the analog-to-digital conversion data and the absolute value according to the information of phase A and phase B shown in (B) of FIG7 (S731), and calculates the data of the width of phase Z synchronized with the lifting of phase A and phase B (S732). In addition, according to the data of the width of phase A, phase B, and phase Z, the data of phase U, V, and phase W as shown in FIG9 is generated (S733), and the data of phase A, phase B, phase Z, phase U, V, and phase W are addressed and recorded as incremental data in EEPROM-3 (S734).

Next, the signal processing in the second magnetic sensor signal processing unit in the first embodiment is explained with reference to Figures 10 and 11.

From each Hall element H1~H3 constituting the second magnetic sensor, a sin signal (H1~H3, H2 sin signal, H3 sin signal) waveform can be obtained as shown by the solid line in Figure 10 (A) as the second analog signal, which rises or falls every 180 degrees during one rotation. This waveform shows the data after the distortion compensation is completed according to the setting position. The position error of the Hall element as the second magnetic sensor, the deviation of the element characteristics, the ambient temperature, etc. cause a large change. The dotted line shown in Figure 10 (A) shows the output of the corresponding first magnetic sensor.

The data of the analog output of the Hall element is recorded in the memory by establishing a relationship with the data of the rotation number Nx and the temperature Ta. The data of the analog output of the Hall element that is established in a relationship with the data of the temperature Ta can also be expressed by an approximate formula in the same way as the above formula (1).

Furthermore, the first analog signal (sin, cos) of the first magnetic sensor signal processing unit 15 and the amplitude detection unit 151 obtain the rotation angle (mechanical angle) and amplitude of the analog signal of the first magnetic sensor 111, the number of rotations Nx, and the data of the temperature sensor 13. Furthermore, based on the rotation angle (mechanical angle) and amplitude of the first analog signal, the number of rotations Nx, and the temperature Ta of the temperature sensor 13, the second analog signal of the second magnetic sensor 112 is subjected to amplitude correction and synchronization correction for each rotation of the second analog signal, that is, the data is corrected, and the corrected analog data is associated with the number of rotations Nx and the temperature Ta data, and recorded in the EEPROM-4 (165) together with the correction process. FIG10(B) shows an example of analog data of the calibrated second magnetic sensor 112.

This calibration process can also be expressed as the aforementioned analog data y2 after calibration using the approximate formula y2(x,tTa) representing the trigonometric function of the SIN wave and COS wave of the first analog signal.

The calibrated analog data is input to the analog-to-digital converter 162 (ADC-3~5) and converted into digital values. These converted values are recorded in EEPROM-5 as time series data.

FIG10(C) shows an example of data after digital conversion of the signal of the second magnetic sensor 112 into digital values including information of phase A and phase B.

FIG10(D) shows an example of a (provisional) absolute value based on the output of the second magnetic sensor signal. The (provisional) absolute value shown by the solid line includes phase errors and the like depending on the characteristics of the second magnetic sensor. (In addition, the errors are exaggerated for easy understanding). In particular, it is conceivable that digital conversion is performed in a state where the error caused by the influence of the temperature Ta in the second analog signal stage cannot be fully eliminated. The dotted line shown in FIG10(D) shows the absolute value based on the output of the corresponding first magnetic sensor.

In the digital signal detection and frequency/rotation direction correction unit 1631 of the second magnetic sensor signal processing unit 16, multi-rotation information including rotation direction, rotation angle, and rotation number is generated from the origin information and the absolute value and recorded in EEPROM-7 (S911 in Figure 11).

That is, the digital signal detection and frequency/rotation direction correction unit 1631 of the second magnetic sensor obtains the frequency/rotation direction data of the digital signal of each rotation of the first magnetic sensor generated by the digital signal and frequency/rotation direction detection unit 1531 of the first magnetic sensor, and synchronizes and corrects the rotation direction of the (tentative) absolute data of the time series of the second magnetic sensor, and records the result as the (formal) absolute data of the second magnetic sensor in EEPROM-7. In addition, the correction process of the absolute data is recorded in EEPROM-6.

FIG10(E) shows an example of the (formal) absolute value of the output based on the second magnetic sensor signal. The absolute value of FIG10(E) can also be approximated by a linear function as mentioned above.

In FIG. 11 , the second magnetic sensor signal processing unit 16 obtains information about the poles of the motor and the origin of the rotation axis from the initial setting value (S901). The approximate expression of the trigonometric function or the data of the linear function used for data correction can also be obtained from the initial setting value.

The second magnetic sensor signal processing unit 16 then obtains the calibrated analog-to-digital conversion data of the second magnetic sensor signal (Sin wave) from EEPROM-6 (S902). In addition, based on the analog-to-digital conversion data, the digital waveform is interpolated by time division as needed, and converted into data showing the absolute position from the origin, such as a 23-bit rotation angle, and the (tentative) absolute value is calculated (S903). Then, the (tentative) absolute value is addressed to the memory and recorded in the memory (S904).

The absolute signal generating unit 1632 of the second magnetic sensor of the digital signal processing unit 163 calculates the number of rotations from the origin information and the absolute value (S921), generates multi-rotation absolute information, and records it in EEPROM-7 as multi-rotation absolute data (S922).

The incremental A, B, Z, (U, V, W) signal generating unit 1633 of the second magnetic sensor of the digital signal processing unit 163 calculates the data of the A phase and the B phase from the analog-to-digital conversion data and the absolute value (S931), and calculates the data of the width of the Z phase synchronized with the lifting of the A phase and the B phase (S932), and generates the data of the U, V, and W phases based on the data of the width of the A phase, the B phase, and the Z phase (S933), addresses the data of the A phase, the B phase, the Z phase, the U, V, and the W phase, and records them as incremental data in the EEPROM-8 (S934).

Next, the processing of the fail-safe control unit 145 in the first embodiment will be described with reference to FIG. 12.

First, obtain information related to the normal determination of the data of EEPEOM1~3, 4~8 from the initial setting unit (S1001). Then, monitor the data of each rotation of EEPEOM1~3 (S1002). Also, monitor the data of each rotation of EEPEOM4~8 (S1003). In addition, the data can be monitored not every rotation, but also at a predetermined time period.

Next, determine whether all data are normal (S1004). If they are normal, perform normal operation (S1005) and continue until the operation is completed (S1006, S1007). If not all data are normal in S1004, then determine whether the data of EEPEOM1~3 are normal (S1010). If they are normal, perform abnormal display of the second magnetic sensor or the processing unit of the second magnetic sensor signal (S1011), and perform quasi-normal operation with the data of EEPEOM1~3 (S1012), and continue until the operation is completed (S1013, S1014). If the data of EEPEOM1~3 is not normal in S1010, then determine whether the data of EEPEOM4~8 is normal (S1020). If it is normal, perform an abnormal display of the first magnetic sensor or the processing unit of the first magnetic sensor signal (S1021), and perform a fail-safe mode operation with the data of EEPEOM4~8 (S1022), and continue until the operation ends (S1023, S1024). If the data of EEPEOM4~8 is not normal in S1020, perform an encoder error display (S1030), and perform the operation end processing (S1031, S1032).

Next, the data processing (S1101) of the processing unit for the second magnetic sensor signal during the normal operation of the rotary encoder will be described with reference to FIG. 13.

The processing unit of the second magnetic sensor signal processes the initial setting value from the data of the second magnetic sensor during normal operation, and obtains the information of the pole number of the motor and the origin of the rotation axis (S1012). In addition, the data of the second analog signal of the second magnetic sensor is obtained and distortion correction processing is performed (S1103). In addition, the data of the first analog signal of the first magnetic sensor that has a synchronous relationship with the signal of the second magnetic sensor is obtained (S1104).

Next, the amplitude of the second analog signal data of the second magnetic sensor is corrected according to the amplitude of the first analog signal data of the corresponding first magnetic sensor (S1105). And, the corrected analog signal data of the second magnetic sensor is recorded in EEPROM-4 (S1106). In addition, the analog signal correction process is recorded in EEPROM-4 (S1107). Then, the corrected analog signal data is converted from analog to digital by the analog-to-digital converter 162, and the second digital data is recorded in EEPROM-5 (S1108).

Next, the second digital data of the second magnetic sensor is obtained from EEPROM-5 (S1109), and the rotation angle and rotation direction of the second digital data of the second magnetic sensor are corrected according to the rotation angle and rotation direction of the first digital data of the corresponding first magnetic sensor (S1110). In addition, the corrected digital data of the second magnetic sensor is recorded in EEPROM-6 (S1111). In addition, the correction history of the second digital data is recorded in EEPROM-6 (S1112). Repeat the above processing until the operation is completed.

Next, the data processing (S1201) of the processing unit for the second magnetic sensor signal in the fail-safe mode of the rotary encoder is described with reference to FIG. 14.

First, the pole number of the motor, the information of the origin of the rotation axis, and the data for fail-safe control are obtained from the initial setting value (S1202). Then, the data of the second analog signal of the second magnetic sensor is obtained (S1203). In addition, the data of the correction process of the analog signal is obtained from EEPROM-4 (S1204). And, according to the data for fail-safe control and the correction process of the analog signal, the distortion and amplitude of the data of the second analog signal of the second magnetic sensor are corrected (S1205). In addition, the corrected analog signal data of the second magnetic sensor is recorded in EEPROM-4 (S1206). In addition, the analog-to-digital converter 162 performs analog-to-digital conversion on the corrected analog signal data, and the second digital data is recorded in EEPROM-5 (S1207).

Next, the second digital data of the second magnetic sensor is obtained from EEPROM-5 (S1208). On the other hand, the data of the digital data correction process is obtained from EEPROM-6 (S1209). And, according to the data for fail-safe control and the data of the (digital data) correction process, the rotation angle and rotation direction of the second digital data of the second magnetic sensor are corrected (S1210). In addition, the corrected digital data of the second magnetic sensor is recorded in EEPROM-6 (S1211). Repeat the above processing until the operation is completed.

According to an embodiment of the present invention, a rotary encoder can be provided, wherein the rotary encoder corrects the second digital data of the second magnetic sensor based on the first digital data of the first magnetic sensor, and can correct the second digital data of the second magnetic sensor during backup control based on these correction processes, so that a low-cost second magnetic sensor with low accuracy can be used while performing backup control with high reliability.

In addition, as an embodiment of the present invention, an AMR (Anisotropic magnetoresistance effect) element may be used as the second magnetic sensor instead of the Hall element. Alternatively, a GMR (Giant magnetoresistance effect) element may be used. These AMR sensors or GMR sensors are also arranged at equal intervals on a circle centered on the first magnetic sensor, similar to the example of the Hall element.

The present invention can also be used in other types of motors, such as stepper motors. In addition, it can be widely applied to various motors such as synchronous motors and induction motors. In addition, the present invention can also be applied to servo control devices using these motors.

10: Rotary encoder 11: Magnetic sensor unit 110: Magnet 111: First magnetic sensor 112: Second magnetic sensor 113: Temperature sensor 115: Barkhausen effect power generation unit 12: Power supply unit 121: Main power supply 122: Barkhausen effect power generation power supply 123: Auxiliary battery 13: Temperature sensor 14: System control unit 141: Initial setting unit 142: Setting unit 143: Fail-safe control data 144: Encoder input/output control unit 145: Fail-safe control unit 146: Output switching unit 147: Serial/parallel signal transmission and reception unit 15: Processing unit for the signal of the first magnetic sensor 151: Analog signal (sin, cos), amplitude detection unit of the first magnetic sensor 152: Analog-to-digital converter 1521: ADC-1 (sin) 1522: ADC-2 (cos) 1523: EEPROM-1 153: Digital signal processing unit 1531: Digital signal, frequency/rotation direction detection unit of the first magnetic sensor 1532: Absolute signal generation unit of the first magnetic sensor 1533: Incremental A, B, Z, (U, V, W) signal generation unit of the first magnetic sensor 16: Processing unit for the signal of the second magnetic sensor 160: Analog signal processing unit 161: Distortion correction, amplitude, and synchronization correction of analog signals of the second magnetic sensor 162: Analog-to-digital converter 1621: ADC-3 1622: ADC-4 1623: ADC-5 1624: EEPROM-5 163: Digital signal processing unit 1631: Digital signal detection, frequency/rotation direction correction unit of the second magnetic sensor 1632: Absolute signal generation unit of the second magnetic sensor 1633: Incremental A, B, Z, (U, V, W) signal generation unit of the second magnetic sensor 164: Fail-safe, signal correction unit 165: EEPROM-4 166: EEPROM-6

Claims (9)

A magnetic rotary encoder comprises: a magnet fixed to a rotating shaft; a first magnetic sensor signal processing unit, which performs analog-to-digital conversion on a first analog signal outputted by a first magnetic sensor disposed opposite to the magnet, and generates first digital data related to a rotation angle and a rotation direction of the rotating shaft according to the analog-to-digital conversion data of the output of the first magnetic sensor, wherein the first digital data includes information of two systems, namely, an absolute signal and an incremental signal; and a second magnetic sensor signal processing unit. , the output of the second magnetic sensor arranged opposite to the aforementioned magnet, i.e., the second analog signal, is converted from analog to digital, and based on the analog-digital conversion data of the output of the aforementioned second magnetic sensor, second digital data related to the aforementioned rotation angle and the aforementioned rotation direction of the aforementioned rotating shaft is generated, and the aforementioned second digital data includes information of two systems, namely, an absolute signal and an incremental signal. The aforementioned magnetic rotary encoder is characterized in that: the resolution of the aforementioned second magnetic sensor is worse than that of the aforementioned first magnetic sensor, and the aforementioned second magnetic sensor signal is The processing unit of the signal has a fail-safe function of backing up the processing unit of the first magnetic sensor signal, and the processing unit of the second magnetic sensor signal has the following functions: based on the data of the first analog signal of the first magnetic sensor, correct the second analog signal of the second magnetic sensor and perform the analog-to-digital conversion, and correct the analog-to-digital conversion data output by the second magnetic sensor based on the first digital data of the first magnetic sensor to generate the second analog signal. digital data, and records the calibration history of the aforementioned second analog signal and the calibration history of the aforementioned second digital data. The aforementioned fail-safe function of the aforementioned magnetic rotary encoder is constituted as follows: When the aforementioned first magnetic sensor and/or the aforementioned first magnetic sensor signal processing unit fails, the aforementioned second analog signal of the aforementioned second magnetic sensor is calibrated according to the calibration history of the aforementioned second analog signal, and the aforementioned second digital data of the aforementioned second magnetic sensor is calibrated according to the calibration history of the aforementioned second digital data. As in claim 1, the magnetic rotary encoder, wherein the first magnetic sensor is arranged on the printed circuit board at a position corresponding to the axis of the rotating shaft, the second magnetic sensor is on the same plane as the first magnetic sensor on the printed circuit board, and is arranged at intervals of 120 degrees on a circle centered on the axis of the rotating shaft, and a temperature sensor is arranged on the printed circuit board. The magnetic rotary encoder of claim 2, wherein the processing unit of the first magnetic sensor signal has the following functions: performing analog-to-digital conversion and recording the data of the first analog signal of the first magnetic sensor, and establishing a relationship between the rotation angle (mechanical angle) of the first analog signal and the amplitude, the number of rotations Nx, and the data of the temperature sensor, and temporarily recording them in the memory as calibration data for the second analog signal, and the processing unit of the second magnetic sensor signal has the following functions: generating calibrated second analog data according to the second analog signal of the second magnetic sensor and the calibration data of the second analog signal, and recording the calibration history of the calibrated analog data for use in the fail-safe function. As in claim 2, the magnetic rotary encoder, wherein the processing unit of the first magnetic sensor signal has the following functions: detecting and recording the frequency and the rotation direction of the first digital data of the first magnetic sensor, and establishing a relationship between the rotation angle (mechanical angle) of the first digital data and the amplitude, the number of rotations Nx, and the data of the temperature sensor, and temporarily recording them in the memory as calibration data for the second digital data, and the processing unit of the second magnetic sensor signal has the following functions: According to the calibration history of the second digital data, calibrate and record the second digital data of the second magnetic sensor, and record the calibration history of the calibrated second digital data for use in the fail-safe function. As in claim 2, the magnetic rotary encoder, wherein the magnet fixed to the rotating shaft is a flat magnet, the first magnetic sensor is a pair of TMR sensors arranged on the printed circuit board facing the magnet, and the second magnetic sensor is three Hall elements arranged at equal intervals on a circle centered on the first magnetic sensor. As in claim 2, the magnetic rotary encoder, wherein the magnet fixed to the rotating shaft is a flat magnet, the first magnetic sensor is a pair of TMR sensors arranged on the printed circuit board facing the magnet, and the second magnetic sensor is three GMR sensors or AMR sensors arranged at equal intervals on a circle centered on the first magnetic sensor. The magnetic rotary encoder of claim 1, wherein the processing unit for the first magnetic sensor signal generates a first absolute signal and a first incremental A, B, Z, (U, V, W) signal based on the analog-to-digital conversion data outputted from the first magnetic sensor as the first digital data, and the processing unit for the second magnetic sensor signal generates a second absolute signal and a second incremental A, B, Z, (U, V, W) signal based on the analog-to-digital conversion data outputted from the second magnetic sensor as the second digital data. As claimed in claim 2, the magnetic rotary encoder comprises a main power source whose output voltage is controlled to a predetermined power, a Barkhausen effect power source, and an auxiliary battery as a power source unit, the Barkhausen effect power source and the auxiliary battery are power sources for performing the backup when the main power source is lost, and the auxiliary battery has a capacitor charged by the Barkhausen effect power source. A backup control method for a magnetic rotary encoder is the backup control method for a magnetic rotary encoder as claimed in claim 1, characterized in that: the first analog signal, the second analog signal, the first digital data, and the second digital data are monitored, and when it is determined that the first magnetic sensor or the processing unit of the first magnetic sensor signal is abnormal in the monitoring results of the above-mentioned data, a calibrated analog signal based on the calibration process of the second analog signal is generated for the second analog signal of the second magnetic sensor in the processing unit of the second magnetic sensor signal, and the calibrated second digital data is generated based on the calibrated analog signal and the calibration data of the second digital data.

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