JPH04276805A - Motor control circuit - Google Patents

Abstract

PURPOSE:To carry out the position control in accordance with an external command by using an advanced function of the integrated circuit for motor control. CONSTITUTION:In a circuit that inputs encoder signals A and B from an encoder 2 and control data to control a servomotor 4, the motor control circuit carries out prescribed processing on a control instruction input means 11 for providing control data having the content of a stop instruction, command pulses C and D to be externally inputted, and encoder signals A and B to prepare pseudo encoder signals A' and B' and to supply the input terminal of control IC1 for encoder signal with pseudo encoder signals A' and B'.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control circuit, and more particularly to a motor control circuit that can perform position control in accordance with external commands by utilizing the advanced functions of a control integrated circuit (IC). .

2. Description of the Related Art Generally, a servo motor or the like is provided with a motor control circuit for receiving command pulses from the outside and controlling the position thereof. This motor control circuit feeds back an encoder signal from an encoder, which is a speed sensor attached to the rotating shaft of a servo motor, to the control system, and directly uses this feedback signal to determine the position while comparing it with external command pulses. Performs speed control. That is, the above encoder signal is
For example, it consists of two incremental signals, A phase and B phase, whose phases are shifted by 90 degrees from each other, and the rotating direction is , and the amount of movement can be detected based on the number of pulses. Then, this encoder signal and external command pulses are compared and processed, and the motor drive circuit is operated by the output.
Performs position and speed control. By the way, recently, integrated circuits (ICs) dedicated to controlling motors with numerous functions have been developed.
has been developed. As shown in Fig. 2, this control I
C1 includes a processor (not shown) for position and speed control therein, receives an encoder signal from the encoder 2 as a feedback signal, receives control data from the host computer, and outputs the result to the drive circuit 3. Thus, the positioning control of the servo motor 4 is performed. As a result, it has many functions such as enabling high-precision digital positioning control in real time through an interface with a host computer, and is likely to be widely adopted in motor control circuits.

0002

[Problem to be solved by the invention] By the way, the above control I
C is configured to input an encoder signal from an encoder, but is not configured to input external command pulses, and all control data is input from a host computer. Therefore, no problem occurs when the motor is always controlled via the host computer, but when it is desired to perform positioning control of the motor according to the number of command pulses as was conventionally done, in other words, pulse control is used. If you want to do this, you cannot meet this request and, for example, you have to create a complicated program to input data into the microcomputer each time, which is extremely inconvenient. Furthermore, when this control IC is adopted, a host computer for inputting control data, a communication line such as an interface, and the creation of a complicated control program are required. The present invention has focused on the above-mentioned problems and has been devised to effectively solve them. An object of the present invention is to provide a motor control circuit that can perform positioning control in accordance with external command pulses by utilizing the advanced functions of a control IC.

0003

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a motor control circuit having an input terminal for inputting an encoder signal fed back from an encoder and an input terminal for inputting control data. a predetermined control command input means that applies a predetermined control command signal to the input terminal for control data; and a pseudo encoder signal is formed by performing predetermined processing on the encoder signal and command pulses input from the outside; and an additional circuit for applying a signal to the feedback input terminal.

[Operation] With the above configuration, a stop command is inputted as a predetermined control command signal to the input terminal for inputting control data so as to stop at the same position, and the memory of the control IC is initialized and stored. I'll let you. On the other hand, in the additional circuit,
An encoder signal consisting of a pulse train fed back from the encoder and a command pulse are input, and a pseudo encoder signal with the same content is formed based on the encoder signal, while a pseudo encoder signal indicating the inverted result of the command content is generated based on the command pulse. Form the encoder signal. These pseudo encoder signals are then supplied to a terminal of the control IC into which the encoder signal is input. This makes it possible to control the positioning of the servo motor while using a highly functional IC dedicated to control.

0004

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motor control circuit according to the present invention will be described in detail below with reference to the accompanying drawings. Note that the same parts as in the conventional device are given the same reference numerals. As shown in Figure 1, 4
is a servo motor as an example of a controlled object, and this servo motor 4 is, for example, an AC servo motor or a DC servo motor.
Consists of servo motors, etc. The rotating shaft 6 of the servo motor 4 is provided with, for example, an incremental encoder 2 as rotation speed detection or position detection means.
It has three phases, an A phase and a B phase, and is configured to output two encoder signals. The servo motor 4 configured as described above is provided with a motor control circuit. Specifically, this motor control circuit 10:
A dedicated control integrated circuit (
IC) 1 and a predetermined control command input means 11 for applying a predetermined control command to the control data input terminal of the control IC 1.
and an additional circuit that performs predetermined processing on the encoder signals A, B and command pulses C, D input from the outside to form a pseudo encoder signal, and supplies this signal to the control IC 1, which is a feature of the present invention. It is mainly composed of 15. FIG. 3 is a detailed configuration diagram of the motor control circuit, and as shown in the figure, the control IC 1 is an example of an LM628-6 having a microprocessor for speed control.
is used. Further, as the predetermined control command input means 11, for example, a microcomputer that can output only a very simple single control command is used, and this control command input means 11 and the control IC 1 are used.
are connected via a data bus 16, an I/O bus 18, and an address bus 20. In this embodiment, this predetermined control command input means 11 does not output various control data, but simply outputs a stop command as an initialization signal, and this initialization signal is used as a control input signal.
It is latched at C1.

Further, a clock generator 22 is connected to the clock terminal CLK of the control IC 1, and the 8-bit output terminal group DAC0 to DAC7 makes full use of the 12-bit D/A converter 24 according to the output from this. Therefore, by passing a latch circuit 26 partially in the middle,
It is converted into bits and input to the input terminal group D of the D/A converter 24.
Connected to B0-DB11. And this D/A
The output of the converter 24 is connected to a drive circuit 3 consisting of a power amplifier to control the position of the servo motor 4. Furthermore, instead of directly inputting the encoder signals A and B from the encoder 2 to the two terminals A and B for inputting the encoder signals of the control IC 1, the additional circuit 15 processes the encoder signals A and B. Pseudo-encoder signals A' and B' generated by applying the encoder are inputted. On the other hand, the additional circuit 15 latches and stores the signal from the encoder 2 and the signal from the command pulse generator 30 that generates the command pulses C and D.
2, and a programmable ROM 3 that performs predetermined processing on the encoder signals A and B and the command pulses C and D in cooperation with the latch IC 32 to form a pseudo encoder signal.
4, and the encoder signal A
, B are designed to generate a pseudo encoder signal having a signal configuration similar to that of the signals. Specifically, the output value of the pseudo encoder signal corresponding to the processing result is stored in advance in the ROM 34, and by accessing it, the signal can be output. The command pulse is composed of two signals: a command pulse C indicating the direction of movement and a command pulse D indicating the amount of movement, and commands the amount of movement according to the number of pulses of the command pulse D indicating the amount of movement. becomes possible.

The command pulse D indicating the amount of movement and the encoder signals A and B are input to and stored in the D terminal of the latch IC 32, and this latch IC
The Q terminal group of C32 is connected to the A terminal group of the programmable ROM 34, while some of the D terminals and Q terminals are connected. Further, the pulse C indicating the moving direction is directly input to the A terminal of the programmable ROM 34. Outputs from two terminals among the plurality of O terminals of the programmable ROM 34 are output from the latch I
While input to the D7 and D8 terminals of C32, this I
Pseudo encoder signals A' and B' are finally output from the Q7 and Q8 terminals of C32, and these signals are input to the A and B terminals of the control IC1. The programmable ROM 34 stores a predetermined program for generating the pseudo encoder signals A' and B'. Encoder signals A, B and command pulses C, D are performed based on the above program.
The operation of generating the pseudo encoder signals A' and B' formed from the following will be explained in detail. First, FIG. 4 shows encoder signals A and B from the encoder 2 when the servo motor rotates by an appropriate amount, for example, to the right, and FIG. 5 shows encoder signals A and B from the encoder 2 when the servo motor rotates, for example, by an appropriate amount to the left. The leading phase signals are reversed between FIGS. 4 and 5 depending on the direction of rotation. At this time, when the edge parts, which are the changing points of the signals A and B in FIGS. 4 and 5, are detected and internal pulses are generated, the signal changes as shown in the four types of correspondences shown in Tables 1 and 2, respectively. becomes. In addition, in the table below, H indicates high and L indicates low.

[0007]

[Table 1]

[Table 2] Then, the detection of one change in the edge portion of either one of the signals is controlled as being equivalent to one pulse. Therefore, when the servo motor rotates and, for example, five of the four types shown in Table 1 are detected, it can be recognized that the servo motor rotates to the right by an amount equivalent to five pulses. Similarly, if, for example, six of the four types of aspects shown in Table 2 are detected, it can be recognized that the servo motor has rotated to the left by an amount equivalent to six pulses. On the other hand, command pulses C and D as target values generated by the command pulse generator 30 are generated as shown in FIG. Here, when the command pulse C indicating the movement direction is H, it indicates a rotation command to the left, for example, and when it is L, it indicates a rotation command to the right. The number of pulses of the command pulse D indicates the amount of movement or the amount of rotation, and in order to detect the amount of rotation, for example, only the falling edge portion of the command pulse D is detected and the number of pulses is counted. Under such conditions, when the falling edge portion of the command pulse D is detected, one type of mode as shown in Table 3 is obtained.

[Table 3]

[0008] Therefore, the number of detected change points shown in Table 3 corresponds to the number of pulses, that is, the amount to be moved. Next, a description will be given of how a pseudo encoder signal having the same configuration as the encoder signal is generated based on the encoder signal and command pulses detected as described above. First, if you want to rotate by one pulse to the left with command pulses C and D, from the control IC's perspective, a signal indicating the inverted result of this command content, that is, a rotation by one pulse to the right, is sent to the control IC. A signal is generated as a pseudo encoder signal based on Table 4.

[Table 4] The contents of Table 4 are the same as those of Table 1, which shows changes in the encoder signal when the servo motor rotates to the right. Therefore, for example, the immediately preceding pseudo encoder signals A', B
When ' is H, H, a new pseudo encoder signal is formed by changing only the signal B' to L. Control IC 1 receives these pseudo encoder signals A' and B'
As mentioned above, a suspension order has been granted to the
This IC issues a command to rotate the servo motor to the left by one pulse in order to cancel the above-mentioned pseudo rotation, and actually rotates the motor.As a result, from the encoder 2 side, the motor rotates to the left by an amount equivalent to one pulse. A pulse indicating rotation is input. This recognition is performed by detecting one of the four types of aspects shown in Table 2. Based on this input encoder signal, pseudo encoder signals A' and B' with the same content, that is, pseudo encoder signals A' and B' shown in Table 5 whose content is that the motor has rotated to the left by an amount equivalent to one pulse, are generated. do.

[0009]

[Table 5] The contents of Table 5 are the same as those of Table 2, which shows changes in the encoder signal when the servo motor rotates to the left. That is, in this case, since the previous pseudo encoder signals A' and B' are H and L, respectively,
By changing the signal A' to L, new pseudo encoder signals A' and B' are formed. Therefore, since the amount of rotation and the direction of rotation are canceled out, a deviation counter (not shown) provided in the control IC 1 is maintained at zero. It should be noted that although the above explanation has been given for the case of one pulse, it goes without saying that similar processing is performed for the case of multiple pulses. The logical expressions for performing the above processing will be explained below. In the programmable ROM 34 mentioned above, addresses A0 to A8 and data D0 to D7 are assumed. Here, A0 to A8 and D0 to D7 are all 0 or 1
, and * indicates a complement. At addresses 000 (hexadecimal) to 1FF (hexadecimal), it is as follows. D4=(A0*・A3*+A0・A3)・(A1・A2
*+A1*・A2) D5=(A0・A3*+A0*・A3)・(A1*・A
2*+A1・A2) D6=A4・A5*・A6 D7=A4・A5*・A6* Here, D4, D5, D6, and D7 are the logical expressions of Table 6, Table 7, Table 8, and Table 9, respectively. It is.

0010

[Table 6]

[Table 7]

[Table 8]

[Table 9] Here, C0=D7×8+D6×4+D5×2+D4. When C0=0, 3, 5, 7, 10 to 15 (C0 is a natural number), D0=A7 and D1=A8. When C0=1, 8, and 9, D0=A8 and D1=A7*. When C0=2, 4, and 6, D0=A8* and D1=A7. Here, D0 and D1 are pseudo encoder signals A, respectively.
', B'. Note that in Tables 10 and 11 shown below, the pseudo encoder signal does not change because the original input signal does not change or detection is not performed.

[Table 10]

[Table 11] The above calculations are performed from addresses 000 (hexadecimal) to 1FF (1
Hexadecimal), and the obtained results are used in the program RO
Each is stored as M 8-bit data. Next, the operation of this embodiment configured as above will be explained. First, a stop command is outputted to the control IC 1 from a predetermined control command input means 11 consisting of a simple microcomputer, etc., and this stop command is initialized and retained in the memory of the control IC 1, so that future stop commands can be used. There is no need to output a signal, and the deviation counter in this IC1 indicates zero when stopped.

On the other hand, encoder signals A and B from the encoder 2 attached to the servo motor 4 are always sent to the additional circuit 1.
5 and is latched by the latch IC 32. Further, the pseudo encoder signals A' and B' outputted from the additional circuit 15 are in a certain state, for example, L, L state at T1 as shown in FIG. In such a state, at T2, the pulse transmitter 30 outputs a command pulse C indicating the rotation direction and rotation amount or movement amount as a target value.
Output D. As shown in Figure 6 and Table 3, the command pulse C
When is H, it indicates a leftward rotation command, and when it is L, it indicates a rightward rotation command. The number of command pulses D is counted and latched by the additional circuit 15 while referring to the changes in Table 3. Note that the number of command pulses D directly corresponds to the number of pulses to be moved.

[0012] Here, in order to simplify the explanation, it is assumed that the command contents of the command pulses C and D are to rotate one pulse to the left. The content indicating the result, that is, the content indicating that the motor 4 has rotated by one pulse to the right (actually, the motor 4 is not rotating) is created based on Table 1, and the signal is converted into a pseudo encoder signal A', Output as B'. In other words, the information indicating that the rotation has been made by one pulse to the right is based on the immediately preceding pseudo encoder signal A', as described in the example above.
, B' are L, L, so according to Table 4, the signal A'
It is created by changing the signal B' from L to H and keeping the signal B' at L (see FIG. 7). Then, the new pseudo encoder signals A' and B' are transferred to the control IC.
1, this control IC1 determines that it has rotated by one pulse to the right, and since this control IC1 has been given a stop command as described above, the amount of movement of one pulse to the right is determined by To compensate, a command is issued to the drive circuit 3 to rotate to the left by one pulse, thereby causing the servo motor 4 to rotate by one pulse to the left. This rotational movement is detected by the encoder 2 at T3 and generates encoder signals A and B, and the additional circuit 15 to which this encoder signal is input rotates to the left, resulting in a change in any one of the four aspects shown in Table 2. occurs and generates one pulse. Then, pseudo encoder signals A' and B' are created which have the same content as the encoder signals A and B, that is, the content has been rotated by one pulse in the left direction. In this case, the current pseudo encoder signal A',
Since B' has become H and L and indicates rotation to the left, by changing signal A' from H to L and maintaining signal B' at L, a new pseudo encoder signal A is generated.
Make ',B'. Therefore, the control IC 1 inputting the new pseudo encoder signals A' and B' recognizes that the rotation has been made by one pulse each on the left and right sides (actually moves one pulse in the left direction), and then stops the servo motor 4. The number of pulses appearing based on the pseudo encoder signals A' and B' is counted by a deviation counter in the control IC 1, and the servo motor 4 is rotated to perform positioning control so that the deviation counter is maintained at zero. In this way, pseudo encoder signals A', B' are composed of command pulses C, D and encoder signals A,
B and is finally expressed as a difference signal.

In the above explanation, the amount of movement for one pulse was explained, but in reality, a large number of command pulses will be input. Even when a large number of pulses are input, the above-described conversion operation is sequentially performed for each pulse according to the manner shown in Table 4 or Table 5. Then, during the input of command pulses, for example 100 pulses, the servo motor starts rotating when, for example, 5 pulses are input, and in response to this rotation, encoder 2 also outputs changes in encoder signals A and B. will be done. Therefore, changes in encoder signals A and B will naturally be input during the input of the command pulse, but by setting the detection clock frequency sufficiently high, microscopically the changes in both command pulses C and D can be Change points (Figure 6 and Table 3) and change points detected from the encoder signal (Figure 4,
5, Tables 1 and 2) do not occur at the same time. Therefore, Table 4 above based on each change detection pulse
Alternatively, the conversion operation shown in Table 5 converts the pseudo encoder signal A',
As a result, as described above, the command pulse and the encoder signal are combined and a signal indicating the difference between them is output, and the servo motor 4 rotates until the deviation counter in the control IC 1 becomes zero. Positioning is performed. Incidentally, by adding an input from a limit switch to the additional circuit 15, it is also possible to prevent the motor from running out of control. Furthermore, the rightward direction and leftward direction in the above embodiments are merely used to simplify the explanation, and it goes without saying that the present invention is not limited to these directions.

[0014]

[Effects of the Invention] In summary, according to the present invention, the following excellent effects can be achieved. By initializing predetermined control commands in a highly functional motor control IC, highly accurate motor positioning control can be performed based on command pulses from the outside, and usability can be improved. Furthermore, a simple microcomputer is sufficient for inputting control commands during initialization, and the need for a host computer, interface, creation of complex control programs, etc., which were conventionally required, can be omitted.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a motor control circuit according to the present invention.

FIG. 2 is a configuration diagram showing an example of a conventional motor control circuit.

FIG. 3 is a circuit diagram showing details of the motor control circuit shown in FIG. 1;

FIG. 4 is a state diagram showing encoder signals when the servo motor rotates to the right.

FIG. 5 is a state diagram showing encoder signals when the servo motor rotates to the left.

FIG. 6 is a state diagram showing the state of command pulses input from the outside.

FIG. 7 is a state diagram showing states of pseudo encoder signals.

[Explanation of symbols]

1 Control integrated circuit (IC) 2 Encoder 3 Drive circuit 4 Servo motor 11 Predetermined control command input means 15 Additional circuit 30 Pulse generator 32 Latch IC 34 Programmable ROM

Claims (2)

[Claims] 1. A motor control circuit having an input terminal for inputting an encoder signal fed back from an encoder and an input terminal for inputting control data, wherein a predetermined control signal is applied to the input terminal for control data. and an additional circuit that performs predetermined processing on the encoder signal and command pulses input from the outside to form a pseudo encoder signal, and applies the signal to the feedback input terminal. A motor control circuit featuring: 2. The predetermined control command signal outputted by the predetermined control command input means is an initialization signal indicating a stop command, and the additional circuit reverses the command content based on the external command pulse. 2. The motor control circuit according to claim 1, wherein the motor control circuit generates a pseudo encoder signal indicating a result of the encoder, and also forms a pseudo encoder signal having the same content based on the encoder signal.