JPH0626883A - Multiple revolution type absolute encoder - Google Patents

Abstract

PURPOSE:To obtain a small size and compact encoder by reducing the number of bits of the absolute signal in a rotation. CONSTITUTION:By the original point return signal from a driver system to a Zn signal, a motor drives and rotates from A point to CW direction, the position changes to B point and original point return operation is completed and then comutation data, Zn zone data and multiple rotation count data at point B as well as point A are sent to a driver system by way of a transmitted data switching circuit 16 and a conversion circuit 17. In the driver system, the mode is selected to add the counted value at A and B phases besides the one rotation absolute data as the representative of the past. And then on, the one rotation absolute data are renewed by the change of the A and B phases in this mode. As the one rotation absolute data changes at this moment with the resolution of 1/1000 in the driver side, the comutation data signal is changed to sine wave and the motor is driven with the sine wave drive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-rotational absolute encoder for detecting an absolute rotation angle of a rotating body, and more particularly to a rotary encoder incorporated in an AC servomotor.

[0002]

2. Description of the Prior Art Servo motors used for driving various machines include DC servo motors with brushes and brushless A servo motors.
There are C servo motors (DC brushless servo motors), and in recent years, the demand for AC servo motors has increased due to the ease of motor maintenance.

There are various types of position detectors for servo systems, but in recent years, rotary encoders used by incorporating them in servo motors have become widespread. Encoders incorporated in AC servomotors are roughly classified into incremental encoders and absolute encoders.

The output signals of the incremental encoder are, as shown in FIG. 11, signals of A and B phases having a 90-degree phase difference from each other so that the rotation directions can be discriminated, and one rotation of one rotation.
Generally, a pulse reference Z signal and commutation signals U, V, W for switching the energized phase of the AC servomotor are provided. The absolute encoder is an encoder that can recognize the absolute position within one rotation immediately after the power is turned on, and is the origin that is the alignment operation between the machine position and the controller immediately after the power is turned on, which is required in the control system using the incremental encoder. Since it does not require a returning operation, it is becoming popular in servo motors for large robots such as multi-joint robots, and most of them are multi-rotation absolute encoders with a motor rotation count function.

A conventional multi-rotation type absolute encoder will be described below. FIG. 9 shows functional blocks of a conventional multi-rotation absolute encoder.
In FIG. 9, reference numeral 91 is an incremental signal output unit, and 92
Is an absolute signal output unit, 93 is a multi-rotation counter unit, 94 is a backup circuit, 95 is a conversion circuit, and 96 is a reset circuit.

The operation of the multi-rotational absolute encoder configured as described above will be described below. First, when the main power source is on, the incremental signal output unit 91 outputs the A and B signals having a 90-degree phase difference and the Z signal generated once per rotation in accordance with the rotational position of the encoder. Further, from the absolute signal output unit 92 outputs the 2 ⁰ 2 ^K-1 of the signal K bits corresponding to the resolution of 1 rotates one revolution absolute data. Further, the multi-rotation counter 93 counts the number of rotations by using the upper 2 bits 2 ^K-1 and 2 ^K-2 of the absolute signal output.

The conversion circuit 95 converts the one-turn absolute data and the multi-turn count data, which are parallel data, into serial data and sends the serial data to the driver or the NC system. On the other hand, when the main power is turned off, the backup circuit 9
Upper 2 bits of absolute signal output by 4 2 ^K-1
The detection of the 2 ^K-2 signal and the multi-rotation counter 93 are always operating. As a result, even when the main power is turned on again, the number of rotations can be held without being reset, and the number of rotations changed when the main power is turned off can be detected.

The reset circuit 96 initializes the multi-rotation count data of the encoder and the internal abnormal status according to the voltage level of the clear signal from the outside.

FIG. 10 is a diagram showing the circuit configuration of the reset circuit and the signal timing. The clear signal from the outside is signal-processed by a low pass filter by a resistor and a capacitor and a Schmitt buffer to generate a reset signal.

[0010]

However, in the above-mentioned conventional structure, a large number of absolute signals are required to determine the absolute position, and the number of signals increases as the resolution increases. Since it is necessary to increase the number of detection units corresponding to the number of signals and the scale of the processing circuit also increases, there is a problem in that the structure and the circuit scale also increase.

Further, since the encoder data of the conventional configuration is cleared only by the voltage level of the clear signal from the outside, the electric noise from the peripheral equipment cannot be sufficiently removed and the counter clear malfunctions and the position of the equipment is lost. There is a problem of reliability that a shift occurs, and a problem of safety that the malfunction cannot be detected because the malfunction is not transmitted to an external controller or the like.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a small and compact multi-rotation absolute encoder.

[0013]

To achieve this object, a multi-rotational absolute encoder according to the present invention comprises: 1. An incremental signal of A and B phases having a 90-degree phase difference with each other and a pulse of A and B phases. An original signal output unit that outputs a total of three types of signals, a reference signal Zn that is less than the number of two or more, and an M-bit absolute signal that determines the order of Zn, and an absolute signal of 2 and M bits are used. Motor one
A multi-rotation counter that counts the number of rotations in the forward and reverse directions equal to or more than the rotation, 3. The multi-rotation counter function when the main power is turned off, and 2 for determining whether the number of rotations of the original signal output unit is normal or reverse. a backup circuit for detecting operation of the absolute signal of the bit, and Z ₀ signal generation circuit for selecting a Z ₀ signal corresponding from 4, M absolute signal and Zn signal bits to 1 zero value of the rotational absolute data, 5, M A decoder circuit for generating a commutation signal for switching a motor excitation phase and Zn sequence data from a bit absolute signal; and 6, a desired signal from the Zn sequence data, the commutation signal, and the count value from the multi-rotation counter. A receiving circuit for receiving a command from the outside to be selected, 7. a transmission circuit for selecting a desired signal by the command from the outside A switching circuit, 8, a conversion circuit for outputting transmission data as serial data, and 9, detecting that the voltage level of an encoder initialization signal processed by receiving a command from the outside by the receiving circuit is active for a certain period of time Reset circuit that initializes the data of the multi-revolution counter, or initializes the data of the multi-revolution counter by detecting that the voltage level of the encoder initialization signal processed by receiving an external command from the receiving circuit is active for a certain period of time. Reset circuit, a reset confirmation circuit for detecting that the data of the multi-rotation counter after the data initialization has been initialized, and a transmission data switching circuit for converting the result of the reset confirmation circuit as an encoder signal processing status It has a configuration having a function of notifying the outside through a circuit.

[0014]

With this configuration, the number of bits of the absolute signal within one rotation can be reduced as compared with the conventional multi-rotation type absolute encoder, so that the detection unit and the electric circuit unit can be downsized, and the small and compact multi-rotation can be achieved. A rotary absolute encoder can be obtained. Further, by performing the reset circuit configuration, the counter reset confirmation, and the signal handshake with the external system, it is possible to improve the reliability and safety of malfunctions due to external noise and the like.

[0015]

EXAMPLES Examples 1 and 2 of the present invention will be described below.
A description will be given with reference to the drawings.

FIG. 1 is a functional block diagram of the first embodiment of the present invention. In FIG. 1, 11 is an original signal output unit, 12 is a decoder circuit, 13 is a multi-rotation counter, 14 is a Z ₀ signal generating circuit, 15 is a receiving circuit, 16 is a transmission data switching circuit, 17 is a converting circuit, and 18 is a backup circuit. , 19 are reset circuits.

FIG. 2 shows the configuration of the original signal output section 11. Here, 21 is a light emitting element, 22 is a rotary slit plate, 23 is a light receiving element, and 24 is a waveform shaping circuit. In this embodiment, the number of Zn is set to 8 for a three-phase eight-pole AC servomotor, and the resolution of one rotation is 1000 pulses.

FIG. 3 shows signals detected in accordance with the rotation of the rotary slit plate 22. Here, the A and B signals are 9
A signal having a phase difference of 0 degree and an incremental signal that generates 1000 pulses during one rotation, a Zn signal that is synchronized with the A and B phases, eight signals that occur during one rotation, and a 5-bit absolute signal.

FIG. 4 shows the movement of the commutation signal output when the main power is turned on. FIG. 5 is a diagram showing the configuration of the decoder circuit 12, in which commutation data and zone data indicating a region of 1/8 of one rotation are selected from a ROM table by a 5-bit absolute signal.

FIG. 6 shows the configuration and signal timing of the reset circuit 19 for initializing the encoder data.

The operation of the multi-rotation absolute encoder having the above structure will be described below.

First, assuming that the encoder is located at point A in FIG. 4 immediately after the main power is turned on, the original signal output unit 1
The commutation signal and zone data are detected by the 5-bit absolute signal output from 1 and the decoder circuit 12, and data is prepared in the transmission data switching circuit 16. Further, the value of the multi-revolution counter 13, which is detected and held by the backup circuit 18, that is, multi-revolution count data is prepared in the transmission data switching circuit 16. Which of these two data is to be transferred is selected by the transmission data switching circuit 16 via the receiving circuit 15 in response to a data request signal from the driver system, and then transferred via the conversion circuit 17. When the driver system requests commutation data and zone data at point A, which is a stop point, the driver system creates a commutation signal for switching the energized phase of the AC servomotor from the commutation data and starts rotation of the motor. . At this time, since the commutation data is constant, the commutation signal does not change in a sinusoidal wave and has a constant value, so that the commutation signal is driven by the rectangular wave drive.
Further, the position data at the point A has a detection resolution of 1/8 rotation (45 °), and in order to perform highly accurate position control, the A and B signals having a high detection resolution and the Zn signal which is the origin signal and the position signal. Since synchronization is required, the driver system holds the data at point A, that is, the representative value, for the one-turn absolute data until it detects the Zn signal and returns to the origin.

Next, in response to a command for returning to the origin from the driver system to the Zn signal, the motor is driven and the point A to C
When it rotates in the W direction and the position changes to point B, which is the position of Zn, and the return-to-origin operation is completed, the commutation data, Zn zone data, and multi-rotation count data at point B are sent as at point A. Data is transmitted to the driver system via the switching circuit 16 and the conversion circuit 17. In the driver system, the mode in which the value counted in the A and B phases is added to the one rotation absolute data as a representative value until now is added, and thereafter, the one rotation absolute data is updated by the change in the A and B phases in this mode. .

At this time, since the one-turn absolute data changes at a resolution of 1/1000 on the driver side, the commutation signal can be changed in a sine wave shape, and the motor is driven by a sine wave drive.

On the other hand, when the motor rotates in the CCW direction from the point A and passes through the point C, which is the representative value switching point, the representative value of the point A is updated with the zone data indicating the adjacent Z1, and this data or backup The value of the multi-revolution counter 13 detected and held by the circuit 18 is selected by the data request signal from the driver system, and the data is transferred to the driver system via the conversion circuit 17. further,
When the position changes to point D, which is the position of Z1 after passing point C, the origin return is completed in the same way as point B, so the driver system has been able to add A, A The mode in which the value counted in the B phase is added is added, and thereafter, in this mode, the one-turn absolute data is updated by the change in the A and B phases.

Next, the structure and operation of the reset circuit 19 will be described below. 6A and 6B show the reset circuit 1
9 is an example of the circuit configuration and signal timing of FIG. The reset circuit 19 comprises a reference clock, a counter, a flip-flop, and a NAND gate. When the initialization signal is input to the reset circuit via the receiving circuit 15 by the request signal from the driver system, the clock counter operation starts, and if the initialization signal has a width of 4 clocks or more, the signal is valid and multi-rotation is performed. Output a reset signal to the counter. On the other hand, a signal with a short signal width such as ◯ 1 becomes invalid and the counter reset signal is not output. That is, impulses having a short width such as electric noise can be removed by setting the reference clock and the pulse count number.

As described above, the detected representative value of the Z phase is 1
By adopting a system configuration that counts A and B phase signals with a resolution of 1/000, a compact multi-rotation absolute encoder that has a high resolution for absolute position detection while the number of absolute signals within one rotation is small realizable. Further, by detecting that the initialization signal at the time of encoder data reset is active for a certain period of time and performing data reset, it is possible to prevent a reset malfunction due to external noise.

(Second Embodiment) Next, a second embodiment of the present invention will be described below.

FIG. 7 is a functional block diagram of the second embodiment of the present invention. The same parts as those in the first embodiment shown in FIG. FIG. 8 shows an example of the configuration and abnormality determination of the reset confirmation circuit 20 that detects whether the multi-rotation counter data has been initialized.

The reset confirmation circuit 20 judges whether or not the data reset operation is normal from the comparison part of the data of the multi-revolution counter and the initial data, the comparison result and the output of the reset circuit, and the judgment result is transmitted data. It is composed of an abnormality determination unit which is set in the switching circuit.

FIG. 8B shows the contents of the abnormality determination. ○ 1
Indicates that the multi-rotation data does not match the initial value even though the counter is reset.
Indicates that the multi-rotation data is reset (count data is suddenly changed to the initial value) even though the counter is not reset. This abnormal state is transmitted to the driver system via the transmission data switching circuit and the conversion circuit.

As described above, the reset operation of the multi-rotation counter is judged in the encoder, the result is transferred to the driver system and the operation is handshaked, whereby abnormality detection for malfunction and improvement of safety can be achieved. .

[0033]

As described above, the present invention can realize a compact multi-rotation absolute encoder capable of performing high resolution absolute detection only by increasing the resolution of the incremental signal when increasing the resolution of one rotation absolute. is there.

Further, prevention of circuit malfunction due to external noise,
Further, by having an operation determination function and an abnormality transmission to the host system, it is possible to improve the reliability of the system as a whole device.

[Brief description of drawings]

FIG. 1 is a block diagram of a multi-rotation absolute encoder according to a first embodiment of the present invention.

FIG. 2 is a block diagram of an original signal output unit according to the embodiment of the present invention.

FIG. 3 is a timing diagram of detection signals of the multi-rotation absolute encoder according to the embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the one-turn absolute encoder when the main power is turned on in the embodiment of the present invention.

FIG. 5 is an operation explanatory diagram of a one-turn absolute data decoder in the embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of the reset circuit of the multi-rotation counter according to the embodiment of the present invention.

FIG. 7 is a block diagram of a multi-rotation absolute encoder according to a second embodiment of the present invention.

FIG. 8 is an operation explanatory diagram of a data reset confirmation circuit according to the embodiment of the present invention.

FIG. 9 is a block diagram of a conventional multi-rotation absolute encoder.

FIG. 10 is an operation explanatory diagram of a reset circuit of a conventional multi-rotation absolute encoder.

FIG. 11 is an output timing chart of a conventional incremental encoder.

[Explanation of symbols]

11 original signal output unit 12 decoder circuit 13, 93 multi-rotation counter 14 Z ₀ signal generation circuit 15 receiving circuit 16 transmission data switching circuit 17, 95 conversion circuit 18, 94 backup circuit 19, 96 reset circuit 20 reset confirmation circuit 21 light emitting element 22 rotary slit plate 23 light receiving element 24 waveform shaping circuit 51 ROM table 91 A, B, Z output section 92 absolute signal output section

Claims (3)

[Claims] 1. An incremental signal of two phases A and B having a phase difference of 90 degrees, two or more reference signals Zn less than the number of pulses of the phases A and B, and an M-bit of which discriminates the order of Zn. An original signal output section that outputs a total of three types of absolute signals, a multi-rotation counter that counts the number of rotations of the motor in one or more forward and reverse directions using an M-bit absolute signal, and the above when the main power is turned off. A multi-rotation counter function, a backup circuit for detecting the 2-bit absolute signal for determining whether the number of rotations of the original signal output section is normal or reverse, and one rotation from the M-bit absolute signal and Zn signal. Z ₀ signal generation circuit that selects Z ₀ signal corresponding to the zero value of absolute data, and for switching the excitation phase of the motor from the M-bit absolute signal A decoder circuit that generates a commutation signal and Zn sequence data; a receiving circuit that receives an external command to select a desired signal from the Zn sequence data, the commutation signal, and the count value from the multi-rotation counter; A multi-rotation absolute encoder including a transmission data switching circuit that selects a desired signal in response to an external command and a conversion circuit that outputs the transmission data as serial data. 2. A reset circuit for initializing data of a multi-rotation counter by detecting that a voltage level of an encoder initialization signal processed by receiving a command from the outside by a receiving circuit is active for a predetermined time. The multi-rotation absolute encoder according to claim 1. 3. A reset circuit for initializing data of a multi-rotation counter by detecting that a voltage level of an encoder initialization signal processed by receiving a command from the outside by a receiving circuit is active for a certain period of time, and A reset confirmation circuit that detects that the data of the multi-rotation counter after data initialization has been initialized, and the result of the reset confirmation circuit is sent to the outside as an encoder signal processing status via the transmission data switching circuit and conversion circuit. The multi-turn absolute encoder according to claim 1, which has a function.