JP3168861B2 - Rotary encoder receiving circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for receiving data of a rotary encoder for detecting the rotational position of a rotating body, and more particularly to a circuit for receiving data from an AC servo driver corresponding to an incremental encoder. Is what is done.

[0002]

2. Description of the Related Art A brushless DC servomotor and a brushless A servomotor are used for driving various machines.
There is a C servomotor (DC brushless servomotor), and in recent years, a rotary encoder used by being incorporated in a servomotor has become widespread. Encoders incorporated in AC servomotors are broadly classified into incremental encoders and absolute encoders. Incremental encoders are widely used by being attached to AC servomotors of various machines, and occupy the mainstream as AC servo encoders. On the other hand, an absolute encoder is an encoder that can determine the absolute position within one rotation.
Since the home position return operation is not required, it is widely used in servomotors for large robots such as articulated robots.

A conventional incremental encoder and a conventional encoder receiving circuit will be described below with reference to FIG.

An encoder output section 91 is provided with an A-phase signal and a B-phase signal having a phase difference of 90 degrees and an origin reference Z of one pulse per rotation.
Signals and commutation signals CS1, CS2, CS3
Is output from the signal transmission circuit 92, and the servo driver input unit 93 outputs the signals of the A and B phases, Z
The signals CS1, CS2 and CS3 are received in parallel as they are and used for servo processing.

[0005]

However, in the above-mentioned conventional configuration, the number of output signals is large and the number of wirings is large, so mass productivity is poor, and erroneous wiring to equipment and disconnection of signal lines themselves are likely to occur. There was a point.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and eliminates the number of signal lines by transmitting signals serially, and after receiving serial data A, B, Z, C
An object of the present invention is to provide an AC servo driver having both mass productivity and reliability by easily reproducing S1, CS2, and CS3.

[0007]

In order to achieve this object, an incremental encoder receiving circuit according to the present invention receives serial data transmitted from a rotary encoder and has two phases A and B having a phase difference of 90 degrees from each other. Is converted in parallel to the count data counted by the phase of, the phase excitation switching signals (commutation signals) CS1, CS2, CS3 phases of the three-phase AC servomotor and the state information of the reference signal Z indicating the origin during one rotation. A serial / parallel converter, a data latch circuit for latching the count data from the serial / parallel converter, the CS1, CS2, and CS3 phases and the Z state information, and a reproduction for reproducing the A and B2 phases having a phase difference of 90 degrees. A BRM circuit for generating a timing pulse, and a frequency for determining an output frequency of the BRM circuit A constant circuit, wherein a reproduced pulse number counter for counting the number of reproduction timing pulses, a 90 degree phase difference based on the reproduction timing pulse A, B2
And a pulse reproducing circuit for converting the phase into a reference signal Z phase during one rotation.

[0008]

According to this configuration, A, B, Z, CS1, CS
Since the two-phase and two-phase signals can be transmitted as serial data on one line, the number of input signals to the AC servo driver can be reduced, and A, B, Z, CS1, CS2, and CS3 can be easily reproduced, and mass production is excellent. A highly reliable AC servo driver can be obtained.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an encoder receiving circuit diagram in one embodiment of the present invention. In FIG. 1, 11 is a serial / parallel converter, 12 is a data latch circuit, 13 is a microprocessor, 14 is a gate circuit, 15 is a BRM circuit,
16 is a frequency setting circuit, 17 is a reproduction pulse number counter,
18 is a pulse reproducing circuit.

FIG. 2A shows an example of operation waveforms of an up / down counter of a rotary encoder on the transmission side. Here, an example of operation of a 16-bit counter is shown.

FIG. 2B shows an example of the entire operation waveform of the up / down counter of the rotary encoder on the transmission side.

FIG. 3 is a diagram showing the structure of serial data input to the serial / parallel converter 11. One frame of data is composed of a start bit, a mode bit, a data bit, a parity bit, a stop bit, an idle bit, and the like. The interrupt signal input to the microprocessor 13 is generated in synchronization with the serial data frame.

FIG. 4 shows the Z-phase state information in the serial data sent from the rotary encoder on the transmission side.
It shows the Z-phase state information in the change of the Z-phase.

FIG. 5 shows an example of the configuration of the pulse regenerating circuit 18. The A / B phase regenerating circuit 51, the Z-phase initial setting circuit 52,
It comprises a phase-one rotation counter circuit 53.

FIG. 6 shows an example of an A / B phase reproducing operation waveform. The initial setting operation of the A / B phase is performed only once at the time of turning on the power, and the output of the A and B phases is performed every frame thereafter. Shows that

FIG. 7 shows an example of a Z-phase reproduction operation waveform, showing that the Z-phase output is output by the A-phase one-rotation counter circuit 53 after the Z output request signal is set.

FIG. 8 is a flowchart showing the operation of the microprocessor according to one embodiment of the present invention.

The operation of the rotary encoder receiving circuit configured as described above will be described. First, data for performing pulse reproduction is transmitted as serial data from a rotary encoder. For example, FIG.
When the power is turned on as in (a), the initial value “3” is set on the encoder side by detecting the current signal levels of the two phases A and B, and when the shaft rotates to CW, 3 → 2 → 1 → 0 → 6.
After that, the counter operates as a cyclic counter as shown in FIG. 2B, and the current count value is set as A / B phase count data information (D0 to D15) for each frame of serial data on the receiving side. To be transmitted.

The Z-phase state information (Z1, Z0) is determined by the change of the Z-phase for each frame of the serial data. Z1 indicates the Z state of the previous frame, and Z0 indicates the Z state of the current frame. Represents. For example, FIG.
At point h, Z1 and Z0 are 0,0 because the Z phase is "L". At point i, Z1 and Z0 are 0,1 because point Z is "H". At point j, Z1 is Z because the Z phase is "H". , Z0 are 1,1. At point k, the Z phase is "L", so that Z1, Z0 are 1,0. FIG. 4 (b)
Indicates that the Z phase is “L” in one frame from the point m to the point n.
→ “H” → “L”, so Z1, Z at point n
0 is 0,1 and Z1, Z0 at point o are 1,0.

Next, the serial data from the rotary encoder is sent to the receiving side in the configuration shown in FIG. The output cycle of the serial data is transmitted at a speed of twice or more the electrical time constant of the motor to be controlled. As described above, the rotary encoder A / A of FIG. 2A and FIG.
B-phase count data and Z in FIGS. 4 (a) and 4 (b)
The phase state information is repeatedly transferred to the receiving circuit side at predetermined time intervals in the serial data configuration of FIG.

Next, the operation of A / B phase reproduction will be described with reference to FIG. A / A detected by the rotary encoder
The B-phase count data is sequentially input to the serial / parallel conversion unit 11 as serial data (RXD), and is sent to the data latch circuit 12 after all bits have been input. Upon completion of the latch, the data latch circuit 12 generates an interrupt request signal shown in FIG. The microprocessor 13 reads the transmitted A / B phase count data from the data latch circuit 12 in the interrupt processing program. If the interrupt processing program is the first time after the main power supply is turned on, the A-phase output and the B-phase output are sent to the pulse regenerating circuit 18 based on the information of the lower two bits (D1, D0) of the current A / B phase count data. An A / B phase initial latch signal is output as a latch signal for initial setting. Further, from the second time on, the microprocessor 13 obtains a difference pulse between the A / B phase count data at the time of the previous interruption and the current A / B phase count data, and writes the difference pulse to the reproduction pulse number counter 17 and the frequency setting circuit 16. At the same time, after outputting a pulse reproduction direction (rotation direction of the motor) signal to the pulse reproduction circuit 18, it outputs a reproduction pulse start signal to the gate circuit 14. The gate circuit 14 outputs the reference clock BR
A clock is output to the M circuit 15, and the BRM circuit 15 outputs a reproduction timing pulse based on the input clock and the frequency determined by the frequency setting circuit 16. The pulse reproduction circuit 18 determines the A-phase output and the B-phase output at the timing of the reproduction timing pulse based on a preset pulse reproduction direction signal. At the same time, the reproduction timing pulse is input to the reproduction pulse number counter 17. Reproduction pulse counter 17
When the number of reproduction pulses is counted down and zero is detected, a pulse reproduction completion signal is output to the gate circuit 14 and the clock output to the BRM circuit 15 is stopped.

By repeating the above operation, the phases A and B
Output phase continuously. Next, FIG.
The operation will be described with reference to FIG. In the above-described A / B phase reproduction operation, when Z1 and Z0 of the Z-phase state information are 0 and 1 for the first time after the main power is turned on, a Z output request signal is sent to the Z-phase initialization circuit 52 in the pulse reproduction circuit 18. Is output. Z
The phase initial setting circuit 52 detects the edge of the A-phase output generated by the A / B-phase reproducing circuit 51 and synchronizes with the next A-phase “L” → “H” → “L” pulse to generate the Z-phase. Is output. In addition, the count value of the A-phase one-turn counter circuit 53 is cleared to zero by the Z-phase output pulse output from the Z-phase initialization circuit. The counter of the A-phase one-turn counter circuit 53 receives the A-phase output of the A / B-phase regenerating circuit 51 and counts up / down the count value (the number of resolution pulses for one rotation of the encoder) preset from the microprocessor 13. At CCW rotation, count up by detecting the rising edge of A-phase. At CW rotation,
Down-counting is performed by detecting the falling edge of the A-phase), and a zero detection signal is output by detecting zero, and the Z-phase is synchronized with the “L” → “H” → “L” pulse of the A-phase. Output.

As described above, the Z-phase position is stored in the A-phase one-rotation counter circuit 53 from the microprocessor 13 only once after the main power is turned on, so that the Z-phase can be generated without management by the microprocessor 13 thereafter. It becomes possible.

Next, an operation flowchart of the microprocessor 13 is shown in FIG. The A and B two-phase reproduction operation and the Z-phase reproduction operation are performed based on the flowchart of the microprocessor 13 in FIG.

In the Z-phase reproducing operation, when the motor rotation speed is high in the frame in which Z1 and Z0 of the Z-phase state information are detected as 0 and 1 for the first time, the A / B phase in the previous interrupt (frame) is detected. The difference pulse number (reproduction pulse) between the count data and the A / B phase count data in the current interrupt (frame) becomes large, which may cause a shift in the original Z-phase output timing in the reproduction pulse. Therefore, every time the microprocessor 13 detects Z1 and Z0 of the Z-phase state information at 0 and 1, the microprocessor 13 determines whether the number of differential pulses is smaller than that at the time when Z1 and Z0 of the Z-phase state information have previously detected 0 and 1. A determination is made. If the current time is smaller, a Z output request signal is output to the Z phase initial setting circuit 52 in the pulse reproducing circuit 18. Thereby, the count value of the A-phase one-turn counter circuit 53 is cleared again,
Since the Z-phase position is stored again, a Z-phase output without deviation can be achieved.

With the above configuration, the signal line can be made into one line by serially transmitting A / B-phase count data, commutation data, Z-phase state information, and the like.
Constructs an AC servo driver that can reduce the number of man-hours for wiring and improve the reliability against disconnection of signal lines, and can accurately reproduce the original A, B 2-phase and Z-phase after receiving serial data. it can.

[0028]

As described above, the present invention provides A, B, Z, C
By transmitting the S1, CS2 and CS3 signals as serial data, the number of signal lines conventionally required 14 can be reduced to four, and A, B, Z, CS1, CS1, CS2, CS
AC that can easily reproduce 3 and has both mass productivity and reliability
A servo driver can be realized.

[Brief description of the drawings]

FIG. 1 is an encoder receiving circuit diagram in one embodiment of the present invention.

FIG. 2 is an operation waveform diagram of an up / down counter of a transmission-side rotary encoder according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of serial data in one embodiment of the present invention.

FIG. 4 is an operation waveform diagram of a Z-phase state information in one embodiment of the present invention.

FIG. 5 is a diagram of a pulse regeneration circuit according to an embodiment of the present invention.

FIG. 6 is an A / B phase reproduction operation waveform diagram in one embodiment of the present invention.

FIG. 7 is a waveform diagram of a Z-phase reproduction operation in one embodiment of the present invention.

FIG. 8 is a flowchart illustrating a microprocessor operation according to an embodiment of the present invention;

FIG. 9 is a transmission / reception configuration diagram of a conventional rotary encoder and a rotary encoder receiving circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Serial-parallel conversion part 12 Data latch circuit 13 Microprocessor 14 Gate circuit 15 BRM circuit 16 Frequency setting circuit 17 Reproduction pulse number counter 18 Pulse reproduction circuit 51 A / B phase reproduction circuit 52 Z-phase initial setting circuit 53 A-phase one rotation counter Circuit 91 Encoder output unit 92 Signal transmission circuit 93 Servo driver input unit 94 Signal reception circuit

Claims (4)

(57) [Claims] A serial data transmitted from a rotary encoder is received, count data counted by two phases A and B having a phase difference of 90 degrees from each other, and a phase excitation switching signal of a three-phase AC servomotor. (Commutation signal) CS1, CS2, CS3 phase, serial / parallel converter for parallel conversion to the state information of reference signal Z indicating the origin during one rotation, count data from the serial / parallel converter, and CS1, CS2 ,
A data latch circuit for latching CS three-phase and Z-phase state information, a BRM circuit for generating a reproduction timing pulse for reproducing into two phases A and B having a phase difference of 90 degrees;
A frequency setting circuit for determining an output frequency of the circuit; a reproduction pulse number counter for counting the number of the reproduction timing pulses; a two-phase A and B phase difference of 90 degrees based on the reproduction timing pulses; A rotary encoder receiving circuit comprising: a pulse reproducing circuit for converting a phase. 2. An A / B-phase reproducing circuit for determining the levels of the A-phase and the B-phase having a phase difference of 90 degrees based on the reproduction pulse timing, and an A-phase generated by the A / B-phase reproducing circuit and an input signal. A Z-phase initialization circuit for performing Z-phase initialization in response to a given Z output request signal, and a counter operation for N-ary up / down detection by detecting a change edge of A-phase after the count is cleared by the Z-phase initialization circuit. 2. The rotary encoder receiving circuit according to claim 1, further comprising a pulse reproducing circuit comprising an A-phase one-rotation counter circuit for performing the above operation and determining the level of the Z-phase signal at a timing when the count value coincides with zero. 3. A data latch circuit, said frequency setting circuit, said reproduction pulse number counter, and said pulse reproduction circuit,
Connected to a microprocessor (CPU) via a bus,
Each time serial data is received, the difference between the A / B phase count data at the previous sampling time and the A / B phase count data at the current sampling time is used to determine the A / B phase count and the frequency setting circuit. / B-phase reproduction pulse number is written and Z
According to the phase state information, an initial setting of the Z-phase generation timing is performed in the pulse reproducing circuit, and after the initial setting, the level of the Z-phase signal is determined by zero coincidence of the A-phase one-turn counter circuit. Claim 1 or Claim 2
A rotary encoder receiving circuit as described in the above. 4. When sampling is performed when serial data is received, when the Z-phase of the Z-phase state information detects an active state, the number of A / B-phase reproduction pulses when the Z-phase active state was previously detected and the current A / B-phase The number of B-phase reproduction pulses is compared, and when the number of A / B-phase reproduction pulses is smaller this time, the initial setting of the Z-phase generation timing is performed again. A rotary encoder receiving circuit as described in the above.