JP2008148504A - Motor control unit, motor control system and arithmetic processing method for controlling motor control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain position data in inputting an external signal with a small number of hardware elements. <P>SOLUTION: A motor control unit (1) includes: a motor driving circuit (11); a receiving circuit (12) for generating position data by receiving the detection signal of an encoder; a counter (13) for counting a first clock signal and receiving a second clock signal at a low frequency to output a counter value; and a CPU (10) for performing arithmetic processing for controlling a motor and synchronizing with the second clock signal to output a command. When the external signal Sd is input, the counter outputs a count value Nx in inputting the external signal. The CPU (10) obtains the position data Px in inputting the external signal from the count value Nx in inputting the external signal output from the counter, a count value N0 output by the counter immediately before inputting the external signal Sd, position data P0 at that time, a count value N1 output immediately after receiving external input and position data P1 at that time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor control device that controls the rotational position of a motor equipped with an encoder, and more particularly to a motor control device that uses the rotational position at the time when an external signal is input for position control.

When position control is performed using a slider or the like that uses motor rotation as power, it is conceivable that the physical position of the slider is obtained using an external signal such as a position detection switch and used for position control.
A conventional motor control device that controls a motor having a serial encoder includes a circuit that receives serial data and converts it into position data (count data) in a receiving circuit that receives serial data of the encoder, and an encoder It incorporates an up / down counter that simulates the count data and a capture circuit that captures the count data of the up / down counter. The count data is preset in the up / down counter, and the count data of the up / down counter is changed according to the frequency and direction calculated from the count data received this time and the change in the count data received up to the previous time. An estimated value of data is derived, and count data of the up / down counter is captured at a timing synchronized with an external event using the capture circuit (see Patent Document 1).
As described above, the conventional motor control device including the serial encoder uses a plurality of circuits and hardware elements in order to estimate and detect the position where the external signal is input.
Japanese Patent Laid-Open No. 2001-82983 (page 2-4, FIG. 1)

However, in the case of a conventional motor control device, as shown in FIG. 1 of Patent Document 1, a plurality of circuits and hardware elements are required to estimate and detect the position at the time when an external signal is input. There was a problem that it was expensive.
The present invention has been made in view of such problems, and in a motor control device that controls the position of a motor equipped with a serial encoder, position data at the time of external signal input can be obtained with a small number of hardware elements. An object of the present invention is to provide a motor control device that controls the position of the motor based on the position data.

In order to solve the above problem, the present invention is as follows.
According to a first aspect of the present invention, there is provided a motor drive circuit for supplying current to a motor for driving, a receiving circuit for receiving a detection signal of an encoder for detecting the position of the motor to generate position data, and a first clock signal. In addition, a counter that outputs a second clock signal having a frequency lower than that of the first clock signal, and a position command and position data are input to perform motor control calculation processing and drive the motor in synchronization with the second clock signal. In a motor control device comprising a CPU that outputs a command to a circuit, when the external signal Sd is input, the counter outputs a count value Nx at the time of external signal input that is a count value at that time, and the CPU outputs an external signal output by the counter The count value Nx at the time of signal input, the count value N0 output by the counter immediately before the external signal Sd is input, and the position data P at that time The position data Px at the time of external signal input is obtained from 0, the count value N1 output immediately after receiving the external input and the position data P1 at that time, and the motor control calculation processing is performed using the position data Px as a reference position. In addition, the position data Px at the time of external signal input is obtained by one of the following formulas.
Px = P1- (P1-P0) (N1-Nx) / (N1-N0) (1)
Px = P0 + (P1-P0) (Nx-N0) / (N1-N0) (2)
However, N0: the previous count value of the counter
N1: Current count value of the counter
Nx: Count value when an external signal is input to the counter
P0: Previous position data
P1: Current position data
Px: Position data when an external signal is input. The second invention is characterized in that in the first invention, a communication delay time is taken into account after the encoder detects the position until the receiving circuit receives the detection signal. .
The third invention is characterized in that the signal of the encoder is serial data, and the receiving circuit to which the serial data is input converts the position data into a format that can be captured by the CPU and outputs it.
4th invention consists of the motor control apparatus of 1st thru | or 3rd invention, the motor driven by this motor control apparatus, and the encoder which detects the rotational position of a motor and outputs it to a motor control apparatus. It is characterized by.

  According to the first to fourth inventions, when the external signal Sd is input, the counter outputs the count value Nx when the external signal is input at that time, immediately before the external signal input count value Nx output by the counter and the external signal is input. The position data Px at the time of external signal input is obtained from the count value N0 output by the counter and the position data P0 at that time and the count value N1 output immediately after receiving the external signal and the position data P1 at that time. As a result, the number of circuits and hardware elements can be reduced as compared with the conventional motor control apparatus, and the apparatus can be made inexpensive.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a configuration of a motor control device according to the present invention. In the figure, 1 is a motor control device of the present invention, 2 is a motor driven by the motor control device 1, and 3 is a serial encoder for detecting the rotational position of the motor 2. Reference numeral 10 denotes a CPU that performs motor control calculations, 11 a motor drive circuit that applies current to the motor 2 according to the calculation results of the CPU 10, and 12 can receive serial data transmitted from the serial encoder 3 and input it to the CPU 10. A receiving circuit 13 that generates and outputs position data P in a format, receives a clock signal C of the crystal resonator 14, generates a first clock signal Cc and a second clock signal Co, and counts the first clock signal Cc The counter 14 outputs a count value N in synchronization with the second clock signal Co, and 14 is a crystal oscillator that supplies the clock signal C to the CPU 10 and the counter 13. A known motor control circuit 11 is used. The first clock signal Cc is obtained by frequency division based on the clock signal C of the crystal resonator 14 and has a lower frequency than the clock signal C. Similarly, the second clock signal Co is obtained by frequency division based on the first clock signal Cc and has a lower frequency than the first clock signal Cc. Although not shown, the first clock signal Cc and the second clock signal Co are also output to the CPU 10.
As described above, the motor control device of the present invention includes the CPU 10, the motor driving circuit 11, the receiving circuit 12, the counter 13, and the crystal oscillator 14. The counter 13 in the figure has a predetermined data length such as 16 bits or 32 bits, and outputs a count value N in synchronization with the second clock signal Co. In addition, the counter 13 also outputs the count value N when an external signal Sd is input. It is designed to output.
The motor control device of the present invention is different from the conventional motor control device in that the receiving circuit 12 receives serial data transmitted from the serial encoder 3 and converts it into position data P in a format that can be input to the CPU 10, and outputs it. The counter 13 having the above function is provided for detecting position data when an external signal is input. For this reason, fewer hardware elements are used compared to conventional motor control devices.

When such a motor control device operates, it is as follows. When the motor control device 1 is driving the motor 2, the serial encoder 3 detects the rotational position of the motor 2, outputs serial data, and transmits it to the motor control device 1. When the receiving circuit 12 receives this serial data, it creates and outputs position data P in a format that the CPU 10 can capture. The position data P output from the receiving circuit 12 and input to the CPU 10 in synchronization with the second clock signal is used for control calculation processing. The CPU 10 receives the count value of the counter 13 output in synchronization with the second clock signal Co, and the count value of the counter 13 output in synchronization with the next second clock signal Co together with the position data P at that time. Hold until
Next, a method for calculating the position data Px when the external signal Sd is input will be described with reference to FIGS.

  FIG. 2 is a chart showing the relationship between the first clock signal Cc, the second clock signal Co, the external signal Sd, time, and the like. In the example of this figure, the second clock signal changes from Lo to Hi at time t1 and time t2, the count value of the counter 13 at time t1 is N0, and the position data received by the CPU 10 from the receiving circuit 12 at that time is P0, the count value of the counter 13 at time t2 is N1, the position data received by the CPU 10 from the receiving circuit 12 at that time is P1, and between time tx and time tx ′ between time t1 and time t2. Shows a state in which an external signal Sd is input. Time tx and time tx ′ are times synchronized with the first clock signal Cc.

FIG. 3 is a diagram illustrating a method for obtaining the position data Px at the time when the external signal Sd is received between the time tx and the time tx ′. The horizontal axis is an axis indicating the count value of the counter 13 and is also a time axis. The vertical axis is an axis indicating position data. From the description of FIG. 2, the position data is P0 when the count value of the counter 13 is from N0 to N1, that is, from time t1 to time t2, and the position data is P1 after the count value of the counter 13 is after N1, that is, after time t2. It has become a staircase. Since the time between t1 and t2 is constant, the position data Px can be obtained by drawing the broken line connecting (N0, P0) and (N1, P1) in the figure and obtaining the intersection of the time tx, that is, the count value Nx. According to FIG. 3, Px can be calculated by the equation (1) or (2).
Px = P0 + (P1-P0) (Nx-N0) / (N1-N0) (1)
Px = P1- (P1-P0) (N1-Nx) / (N1-N0) (2)
Here, N1 is the count value of the counter 13 at time t2,
N0 is the count value of the counter 13 at time t1,
Nx is the count value of the counter 13 at time tx,
P1 is the position data input to the CPU 10 at time t2,
P0 is the position data input to the CPU 10 at time t1.
As can be seen from this equation, the time ratio when the external signal Sd is input with respect to the control calculation cycle is calculated from the count values N1, N0, Nx, and the difference between the position data P1, P0 is multiplied by the time ratio. The position data at the time of external signal input is derived by subtracting from the position data P1 or adding to the position data P0. In this way, the position Px at the time of external signal input can be estimated and detected.

Next, the second motor control device will be described. The second motor control device has the same configuration as the first motor control device shown in FIG. 1, but the processing method of the CPU 10 is slightly different.
FIG. 4 is a diagram corresponding to FIG. 3 in the case where there is a communication delay between the time when the serial encoder 3 detects the position of the motor 2 and the time when the receiving circuit 12 receives the serial data. It is a figure explaining the method of calculating | requiring the position data Px when the counter 13 inputs the external signal Sd. In the upper half, the vertical axis and the horizontal axis are the same as in FIG. 3, and the time axis is added to the lower half.
In this figure, the count value of the counter 13 counted at the rising edge of the second clock signal Co at time t1 is N0, the position data input from the receiving circuit 12 by the CPU 10 is P0, and the rising edge of the second clock signal Co at time t2. The count value of the counter 13 counted in step N1 is N1, and the position data input from the receiving circuit 12 by the CPU 10 is P1. If the transmission delay between the serial encoder 3 and the receiving circuit 12 is td, the position data Px at the time tx when the external signal Sd is input is received by the receiving circuit 12 after the time td from the time tx. Since the position data P is output to the CPU 10, the count value of the counter 13 when the time td has elapsed from the time tx becomes Px.
Therefore, the position data Px when the external signal Sd when the transmission delay is taken into consideration can be obtained by one of the following equations.
Px = P1- (P1-P0) (N1-Nx-Nd) / (N1-N0) (3)
Px = P0 + (P1-P0) (Nx-N0 + Nd) / (N1-N0) (4)
Here, Nd is the count value of the counter 13 corresponding to the transmission delay time from the serial encoder 3 to the receiving circuit 12, and the others are the same as those described in the first embodiment.
The position Px at the time of external signal input in which serial communication delay is compensated can be estimated and detected by any of these equations.

  As described above, the second clock signal Co rises and the next rise time point according to the temporal internal ratio of the external signal Sd input between the rise of the second clock signal Co and the next rise. Since the position data Px at the time of the input of the external signal Sd is obtained using the position data of the motor, the circuit to be used is only the receiving circuit 12 and the counter 13, and the motor control device is obtained by reducing the hardware elements compared with the prior art. Can be made inexpensive.

  In the above description, the counter 13 generates the first clock signal Cc and the second clock signal Co from the clock signal C. However, the function is provided to the crystal oscillator 14 so that the counter 13 and the CPU 10 have the first clock signal. Cc and the second clock signal Co may be output.

The block diagram of the motor control apparatus which shows the Example of this invention The time chart which shows operation | movement of 1st Example of this invention. The figure explaining the calculation of 1st Example of this invention The figure explaining the calculation of 2nd Example of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 2 Motor 3 Encoder 10 CPU 11 Motor drive circuit 12 Reception circuit 13 Counter 14 Crystal oscillator

Claims (9)

A motor drive circuit for supplying current to the motor for driving;
A receiving circuit that receives a detection signal of an encoder that detects the position of the motor and generates position data;
A counter for counting a first clock signal and receiving a second clock signal having a frequency lower than that of the first clock signal and outputting a count value;
A CPU that outputs a command to the motor drive circuit in synchronization with the second clock signal by performing a control calculation process of the motor when a position command and the position data are input;
In the motor control device consisting of
When the external signal Sd is input, the counter outputs a count value Nx at the time of external signal input, which is a count value at that time,
The CPU receives the external signal input count value Nx output from the counter, the count value N0 output by the counter immediately before the external signal Sd is input, the position data P0 at that time, and the external input. The position data Px at the time of external signal input is obtained from the count value N1 output immediately after that and the position data P1 at that time, and the motor control calculation processing is performed using the position data Px as a reference position. Motor control device. 2. The motor control device according to claim 1, wherein the position data Px at the time of input of the external signal is obtained by any one of the following formulas.
Px = P1- (P1-P0) (N1-Nx) / (N1-N0) (1)
Px = P0 + (P1-P0) (Nx-N0) / (N1-N0) (2)
However, N0: the previous count value of the counter
N1: Current count value of the counter
Nx: Count value when an external signal is input to the counter
P0: Previous position data
P1: Current position data
Px: Position data at the time of external signal input A motor drive circuit for supplying current to the motor for driving;
A receiving circuit that receives a detection signal of an encoder that detects the position of the motor and generates position data;
A counter for counting a first clock signal and receiving a second clock signal having a frequency lower than that of the first clock signal and outputting a count value;
A CPU that outputs a command to the motor drive circuit in synchronization with the second clock signal by performing a control calculation process of the motor when a position command and the position data are input;
In the motor control device consisting of
When the external signal Sd is input, the counter outputs a count value Nx at the time of external signal input, which is a count value at that time,
The CPU receives the external signal input count value Nx output from the counter, the count value N0 output by the counter immediately before the external signal Sd is input, the position data P0 at that time, and the external input. The count value N1 output immediately after and the position data P1 at that time, and the count value of the counter corresponding to the communication delay time from when the encoder detects the position until the receiving circuit receives the detection signal A motor control device characterized by obtaining position data Px at the time of external signal input from Nd and performing control calculation processing of the motor using the position data Px as a reference position. 4. The motor control device according to claim 3, wherein the position data Px when the external signal is input is obtained by any one of the following expressions.
Px = P1- (P1-P0) (N1-Nx-Nd) / (N1-N0) (3)
Px = P0 + (P1-P0) (Nx-N0 + Nd) / (N1-N0) (4)
However, N0: the previous count value of the counter
N1: Current count value of the counter
Nd: of the counter 13 with a latch function corresponding to the delay time of serial communication
Count value
Nx: Count value when an external signal is input to the counter
P0: Previous position data
P1: Current position data
Px: Position data at the time of external signal input   4. The motor control device according to claim 1, wherein the encoder signal is serial data, and the receiving circuit receiving the serial data converts the position data into a format that can be captured by the CPU and outputs the position data. .   The motor control device according to claim 1, a motor driven by the motor control device, and an encoder that detects a rotational position of the motor and outputs the detected rotational position to the motor control device. Motor control system. A motor drive circuit for supplying current to the motor for driving;
A receiving circuit that receives a detection signal of an encoder that detects the position of the motor and generates position data;
A counter for counting a first clock signal and receiving a second clock signal having a frequency lower than that of the first clock signal and outputting a count value;
A CPU that outputs a command to the motor drive circuit in synchronization with the second clock signal by performing a control calculation process of the motor when a position command and the position data are input;
In the motor control device consisting of
The CPU
The internal division between the current position data and the previous position data is performed using the internal ratio of the external signal input count value that internally divides the current count value of the counter and the previous count value output in synchronization with the second clock signal. To obtain the position data at the time of external signal input,
A control arithmetic processing method for a motor control device, wherein the motor control arithmetic processing is performed using the position command and the position data when the external signal is input. A motor drive circuit for supplying current to the motor for driving;
A receiving circuit that receives a detection signal of an encoder that detects the position of the motor and generates position data;
A counter for counting a first clock signal and receiving a second clock signal having a frequency lower than that of the first clock signal and outputting a count value;
A CPU that outputs a command to the motor drive circuit in synchronization with the second clock signal by performing a control calculation process of the motor when a position command and the position data are input;
In the motor control device consisting of
The CPU
When the current count value and the previous count value of the counter output in synchronization with the second clock signal are internally divided, the internal ratio is calculated by using the sum of the count value corresponding to the communication delay time and the count value at the time of external signal input. Seeking
By dividing the current position data and the previous position data by the internal ratio, the position data at the time of external signal input is obtained,
A control calculation processing method for a motor control device, wherein the motor control calculation processing is performed using the position command and the position data when the external signal is input.   9. The control arithmetic processing method of the motor control device according to claim 8, wherein the communication delay time is a time from when the encoder detects a position to when the receiving circuit receives the detection signal.

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