JPH07222479A - Driving apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] One servo amplifier controls multiple servomotors. [Structure] The control unit 12 creates an index position, speed, etc. command for each axis according to an index control command from a PC, and supplies this to the servo amplifier unit 14. here,
It is determined whether or not there are a plurality of drive axes, and if there is a plurality of drive axes, the program parameter changing unit 28 for that purpose outputs them. Then, these input signals are input to the servo unit 30. The servo unit 30 has a shaft division processing unit 30a. In this case, in the case of processing of a plurality of axes, a control command for two servo motors is created one by one for each control cycle, and the servo command is generated. The output from the power output unit 34 is continuously performed in two control cycles. Therefore, after the command values for the two servo motor units 16 are created one by one, the output of the current according to the control commands already created is controlled in the next two control cycles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device having a plurality of motors, and more particularly to a drive device capable of changing the number of servo motors to be controlled according to modes.

[0002]

2. Description of the Related Art Conventionally, a plurality of motors have been used for transporting, gripping, moving, and processing objects to be processed in a product manufacturing process of a factory. As such a motor, a servo motor that can control the drive amount of the motor according to an operation command is used.

FIG. 4 shows an example of the configuration of a conventional positioning control device using a servo motor. This positioning control device is an external programmable controller (PC) 100.
The control unit 200, the servo amplifier units 300 and 400, and the servo motor units 500 and 600 are provided. Control part 2
00 is a communication unit 202 with the PC 100 and a command processing unit 2
04, the servo amplifier unit 300, 400
Are servo units 302 and 402, output voltage pattern hold units 304 and 404, and motor power output unit 30, respectively.
It consists of 6,406. Then, the servo motor unit 5
00 and 600 are composed of servo motors 502 and 602 and encoders 504 and 604 for detecting the rotation of the servo motors 502 and 602.

The indexing command issued from the PC 100 is input to the PC communication unit 202 of the control unit 200. The communication unit 202 with the PC performs reception processing according to a predetermined communication protocol, and supplies this to the command processing unit 204. The command processing unit 204 determines which servo motor to command based on the indexing command, creates signals for indexing position and speed commands, and sends the signals to the servo amplifier units 300 and 400. In this example, the instruction is to drive both of the two servo motor units 500 and 600.

Servo unit 302 of servo amplifier unit 300
Generates an output voltage command based on the supplied index position and speed command, and outputs this command to the output voltage pattern hold unit 3
Supply to 04. Output voltage pattern hold unit 304
Holds the pattern of the output voltage and sequentially supplies it to the motor power output unit 306 as an output voltage command in accordance with a predetermined timing. This motor power output unit 306
Incorporates an inverter, converts a DC voltage from a power source for power into a predetermined three-phase AC current by controlling the inverter based on an output voltage command, and outputs this. The drive current from the motor power output unit 306 of the servo amplifier unit 300 is supplied to the servo motor unit 500.

The servo motor unit 500 is for driving the X-axis, and the servo motor 502 rotates in a predetermined manner according to the drive power from the motor power output unit 306 to drive the X-axis. The rotation of this servo motor 502 is
It is detected by the encoder 504 (a predetermined pulse signal is obtained and rotation is detected based on this), and this is supplied to the command processing unit 104. By monitoring the output of the encoder 504, predetermined feedback control is performed, and the driving of the servo motor 502 according to the index command is achieved. The servo motor unit 600 is for driving the Y-axis, and the servo amplifier unit 40 is used for this driving.
0 is provided. The configuration and operation of the servo amplifier unit 400 and the servo motor unit 600 are the same as those of the servo amplifier unit 30.
0, since it is the same as the servo motor unit 500, description thereof will be omitted.

As described above, in the conventional configuration, one corresponding servo amplifier is provided for one servo motor section. Thus, the servo motor is driven according to the indexing command.

[0008]

As described above, in the conventional drive device, a servo amplifier dedicated to controlling one servo motor is provided for each servo motor to maximize the performance of the servo motor. High-speed and accurate drive control. However, with this method, if the number of motors increases,
A corresponding number of servo amplifiers are required. Therefore, there is a problem that a mounting space and a cost burden are large, a system using a large number of motors is very expensive, and the space becomes large.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a drive device in which the number of servo amplifiers can be reduced and the load on the system can be reduced.

[0010]

According to a first aspect of the present invention, in a drive device having a plurality of servo motors, a control unit for controlling the operation of the plurality of servo motors is provided, and the control unit is in the first operation mode. , A current supply command to one servo motor is created from an operation command supplied from the outside, the drive of the one servo motor is controlled based on the created current supply command, and in the second operation mode, It is characterized in that current supply commands to a plurality of servo motors are sequentially created from operation commands supplied from the outside, and drive of the plurality of servo motors is controlled based on the created current supply commands.

The second aspect of the invention is characterized in that the control section changes the cycle for generating the current supply command in accordance with the number of servomotors to be controlled.

According to a third aspect of the present invention, the control unit stores in advance control parameters corresponding to the number of servo motors to be driven, and based on the control parameters, currents to one or a plurality of servo motors are stored. It is characterized by creating a supply command.

According to the fourth aspect of the invention, the operation command supplied from the outside includes information on the number of servo motors to be driven, and the control section determines the operation mode based on this information. It is characterized in that it has a determining means for performing.

[0014]

As described above, in the drive device of the first invention,
The control unit can operate in two operation modes. That is, in one operating mode,
The control unit drives only one servo motor, and the control unit controls a plurality of motors in another operation mode.

Here, the sine wave current flowing in the servo motor will be described. First, the sinusoidal current flowing in the servo motor is created by switching the inverter provided in the servo amplifier. That is, as shown in FIG. 5 (A), switching of each power transistor of the three power transistor pairs arranged between the + pole and the − pole of the DC voltage is controlled to control the three output terminals (power transistor pair). Of the intermediate connection part) a, b, c. That is, the stator winding of the servomotor has a structure as shown in FIG. 5B, and currents ia, ib, and ic flow through the windings. Then, by turning on one upper side transistor of the three power transistor pairs and turning on the other two lower side transistors, a current flows through the stator winding and one phase current is supplied to the servo motor. Can be supplied. Therefore, a desired sine wave can be supplied to the stator winding by controlling the current to flow out from the output terminals a, b, and c in sequence. Further, control for supplying this sine wave uses PWM (pulse width modulation), and as shown in FIG. 6, by controlling the time for turning on the power transistor, a sine wave is generated, This is supplied to the servo motor.

Here, assuming that one control cycle in PWM control is tn, the servo amplifier unit within this control cycle
In the next control cycle, it has to be determined whether the voltage is + or − or 0. Then, the output of the servo amplifier outputs a voltage as a result of calculation in the control cycle of tn-1 during the control cycle tn. Thus, in each control cycle, the output voltage in the next control cycle is calculated and calculated, and the voltage calculated in the previous control cycle is output. Therefore, the shortest length of the control cycle tn is limited by the calculation speed in the servo amplifier section. That is, the shorter the control cycle, the higher the control accuracy, but the control cycle cannot be shortened beyond the limit.

Therefore, in the second aspect of the invention, the control cycle is changed according to the content of the control. That is, when the control accuracy of the servo motor does not need to be so high, 1
Control multiple servo motors with one servo amplifier. The minimum control cycle time in this case is a cycle that can be controlled by one servo amplifier. That is, when controlling two motors, the control cycle is doubled. As a result, the output voltage to the two servo motors can be sequentially calculated and calculated, and the driving of the two servo motors can be controlled. Further, when the accuracy of control of the servo motor is required to be high, the control cycle as described above should not be extended. Therefore, one servo motor controlled by the servo amplifier is used for accurate control.

As described above, according to the second aspect of the present invention, the servo motor can be efficiently controlled as a whole by adaptively controlling the control cycle. Since the number of servo amplifiers can be reduced as compared with the number of servo motors, the size of the entire system can be reduced and a low cost system can be obtained.

According to the third aspect of the invention, the control unit prepares a current supply command to one or a plurality of servo motors according to a control parameter corresponding to the number of servo motors to be driven which is stored in advance. Therefore, it is possible to easily cope with a change in the number of servo motors to be driven.

Further, in the fourth aspect of the invention, since the operation command supplied from the outside includes the information on the number of servo motors to be driven, the control section immediately determines the operation mode based on this information. Can be determined. Therefore, the servo motor can be driven without causing a control delay.

[0021]

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

FIG. 1 is a block diagram showing the overall construction of the embodiment. A control unit 12 is connected to the programmable controller (PC) 10, and two servo motor units 16 a and 16 b are connected to the control unit 12 via one servo amplifier unit 14.
The PC 10 creates various commands according to a program created in advance and outputs them. In this example, a drive command (axis indexing command) for the servo motor is supplied to the control unit 12. The control unit 12 performs a receiving process in the communication unit 20 with the PC according to a communication protocol predetermined with the PC 10. Then, the obtained indexing command is supplied to the command processing unit 22. The command processing unit 22 creates a position indexing command and a speed command for each drive target axis based on the supplied indexing command.

On the other hand, the control section 12 is provided with a drive axis selecting section 24, and the indexing command from the communication section 20 with the PC is also supplied to the drive axis selecting section 24.
The drive axis selection unit 24 determines from the indexing command whether or not this is a command for a plurality of axes, what is the corresponding axis, and supplies an instruction about this to the output voltage switching cycle determination unit 26. To do. The output voltage switching cycle determining unit 26 determines the number of axes to be controlled simultaneously, and supplies this to the program parameter changing unit 28. From this, the program parameter changing unit 28 outputs a command regarding a program parameter for processing in the servo amplifier unit 14. The servo amplifier unit 14 has a servo unit 30, and receives the position index from the command processing unit 22 of the control unit 12, the speed command signal and the parameter signal from the program parameter changing unit 28. Servo unit 3
0 controls the output of the specified number of servo motors according to the signal from the program parameter changing unit 28. For this reason, the servo unit 30 has a built-in axis division processing section 30a. When the number of control axes is plural, the axis division processing section 30a outputs a plurality of signals for each control target. To do. In this example, two servo motors 16a and 16b are used.
Since there are two, the servo amplifier unit 14 has two voltage pattern hold units 32a and 32b and a motor power output unit 3
It has 4a and 34b. And the indexing command is 2
In the case of controlling the driving of one motor, the axis division processing unit 30a outputs signals for each servo motor output to the two output voltage pattern holding units 32a and 32b. The output voltage command value output from the axis division processing unit 30a is output by the output voltage pattern holding unit 3
It is supplied to the motor power output parts 34a and 34b via 2a and 32b, and the switching of the inverter incorporated therein is controlled.

Therefore, the motor power output sections 34a, 3
A drive current for driving the servo motor is output from 4b. The servo motor units 16a and 16b are composed of servo motors 36a and 36b and encoders 38a and 38b, and the servo motors 36a and 36b rotate according to the current output from the motor power output unit 34a. , 38b, and the detected value is fed back to the servo unit 30 and the command processing unit 22. The servo motor unit 30 and the command processing unit 22 perform control so that the rotations of the servo motors 36a and 36b follow the command values according to the detection values from the encoders 38a and 38b.

Next, the operation of the embodiment will be described with reference to FIG. First, the index control command is transmitted from the PC, as in the conventional system. In this case, this indexing control command includes a command for performing simultaneous two-axis control or controlling one axis at a time. In the usual case, the programmer pre-programs whether or not the simultaneous control of two axes is necessary because of the necessity of the accuracy of axis control. It should be noted that, at the time of programming, it is possible to automatically generate a program as to whether or not simultaneous control of two axes is performed by inputting the accuracy of axis movement. Further, the program may include only the value regarding the accuracy of the axis movement, and determine whether or not the two-axis simultaneous control is performed on the receiving side.

The indexing control command output from the PC 10 is input to the communication unit 20 with the PC and, after being received and processed, is input to the command processing unit 22 where the control target axis, indexing position and speed are set. It is determined (S101). On the other hand, PC
The indexing command sent from is supplied to the drive axis selection unit 24, where it is determined whether or not two-axis simultaneous control is performed (S1).
02). Then, in the case of uniaxial control, the output voltage switching cycle determining unit 26 and the program parameter changing unit 28 select a program parameter for uniaxial control (S103). On the other hand, in the case of biaxial control, program parameters for biaxial control are selected (S104). Then, the program parameters selected in S103 and S104 and the control target axis, index position, and speed signals created in S101 are supplied to the servo unit 30. In this servo unit 30,
The output voltage pattern for each motor is determined based on the input information. At this time, the control cycle is changed depending on the number of axes to be controlled. That is, as shown in Table 1, in the control cycle tn, the voltage output to the servo motor 36a is determined during the control cycle of tn + 2 and tn + 3.

[0027]

[Table 1] Then, in the next control cycle tn + 1, tn + 2, tn +
During the control period of 3, the voltage output to the servo motor 36b is judged. Further, during the control cycles tn and tn + 1, the voltage output to the motor 36a continues the voltage output of the result calculated in the control cycle tn-2. Further, the voltage resulting from the calculation in the control cycle of tn-1 is output to the motor 36b.

When the voltage output pattern is determined in this way, it is input to the axis division processing section 30a,
The axis division processing unit 30a determines whether or not there is an output voltage command for the motor 36a (S106), and if there is this output voltage command, outputs the voltage command to the output voltage holding unit 32a of the motor 36a (S107). ). Then, the motor power output unit 34a outputs power to the motor 36a based on the input voltage output command (S10).
8). On the other hand, the axis division processing unit 30a determines in parallel with S106 whether there is an output voltage command for the motor 36b (S109). When there is a voltage output command to the motor 36b, the output voltage command is output to the output voltage hold unit 32b (S110). Then, the motor power output unit 34b outputs a drive current to the servo motor 36b (S111).

In this way, the servo unit 3 in this embodiment is
0 controls servo motors for two axes simultaneously. Therefore, when the two motors are controlled at the same time, the output does not substantially change in two control cycles as described above. Therefore, the current may be different from the ideal current as compared with the uniaxial control in which the voltage value can be changed in each control cycle.

That is, Table 2 shows an example of the output voltage command in the control cycle t0 to t3. According to this example, in the control cycle t0, the voltage output to the motor 36a at t2 and t3 is judged to be +, and the voltage output to the motor 36b at t2 and t3 in the control cycle t1 is-. It is judged to be optimum and t4, t5 in the control cycle t2
It is judged that 0 is the optimum voltage to be output to the control cycle t3.
At +4, it is determined that + is the optimum voltage output to the motor 36b at t4 and t5. Accordingly, in the control cycle t2 to t3, the output voltage for the motor 36a becomes + and the output voltage for the motor 36b becomes-. On the other hand, in the control cycles t4 and t5, the motor 36
The output voltage for a is 0, and the output voltage for the motor 36b is +.

[0031]

[Table 2] Accordingly, the output voltage of the motor 36a and the motor 36a
The output voltage of b is as shown in FIG. in this way,
Since the output voltage is changed every double control cycle, the actual current waveform is as shown by the broken line in the figure, which is slightly different from the ideal current waveform. That is, the pulsation of the current becomes large. However, such two-axis control is limited to the case where the position indexing control or the like can be performed with relatively low accuracy, and thus such control can be sufficiently dealt with. For example, in the program creation stage, after such a two-axis control, a flow for performing accurate position indexing by controlling the one-axis is used.
High-speed operation and accurate position control can also be performed.
Then, in this way, a plurality of motors can be controlled by one servo amplifier. Therefore, the number of servo amplifiers can be reduced, the mounting space can be reduced, and the cost of the device can be reduced.

[0032]

As described above, according to the first aspect of the present invention, one servo amplifier can drive two or more servo motors. Therefore, the installation space can be reduced, and the same processing can be achieved at low cost.

Further, according to the second aspect of the present invention, when two or more servo motors are driven, the control cycle of the servo motors is changed, so that the control unit can be controlled by making maximum use of its capability. . Further, according to the third aspect of the present invention, the control parameter corresponding to the number of servo motors is stored in advance, so that the change in the number of servo motors to be driven can be promptly dealt with. Further, according to the fourth aspect of the invention, by including the information about the number of servo motors to be driven in the command supplied from the outside, the number of servo motors to be driven can be recognized quickly and the delay is not generated. The servo motor can be controlled.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment.

FIG. 2 is a flowchart illustrating the operation of the embodiment.

FIG. 3 is a waveform diagram showing a waveform of an output current in the example.

FIG. 4 is a block diagram showing a configuration of a conventional device.

FIG. 5 is an explanatory diagram showing configurations of an inverter and a motor stator.

FIG. 6 is a waveform diagram showing the flow of current flowing through the stator coil of the motor.

[Explanation of symbols]

 10 Programmable Controller (PC) 12 Control Section 14 Servo Amplifier Section 16 Servo Motor Section

Front page continuation (72) Inventor Minoru Enomoto 1-1, Asahi-cho, Kariya city, Aichi prefecture Toyota Koki Co., Ltd. (72) Inventor Hiroyuki Ito 1-1, Asahi-cho, Kariya city Aichi prefecture Toyota machine (72) Inventor, Ryoichiro Takano, 2-chome, Toyota-cho, Kariya city, Aichi Prefecture Toyota Industries Corporation

Claims (4)

[Claims] 1. A drive device having a plurality of servo motors, comprising a control unit for controlling the operation of the plurality of servo motors, wherein the control unit has an operation command supplied from the outside in a first operation mode. From the operation command supplied from the outside in the second operation mode, by generating a current supply command to one servo motor, controlling the drive of the one servo motor based on the created current supply command. A drive device, wherein current supply commands to a plurality of servo motors are sequentially created, and drive of the plurality of servo motors is controlled based on the created current supply commands. 2. The drive device according to claim 1, wherein the control unit changes a cycle for creating the current supply command according to the number of servo motors to be controlled. 3. The drive device according to claim 1, wherein the control unit stores in advance control parameters corresponding to the number of servo motors to be driven, and based on the control parameters,
A drive device for creating a current supply command to one or a plurality of servomotors. 4. The drive device according to claim 1, wherein the operation command supplied from the outside includes information about the number of servo motors to be driven, and the control unit includes: A drive device having a determination means for determining an operation mode based on this information.