JP2587513B2 - Motor control device and control method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motor control device and method for controlling a motor such as a servomotor used in an industrial robot, and more particularly to a method for controlling a plurality of motors. In the motor control device configured to periodically transmit the control amount calculated by the main control unit to each motor control unit to control the corresponding motor,
The present invention relates to a motor control device and a method for shortening a communication time for each motor control unit.

[Conventional technology]

As an example of a motor control device, FIG. 7 shows the configuration of a digital servo control device in an industrial robot.
In this servo control device, a robot main control unit 100 realized by a microcomputer and first to fourth servo drivers (motor control units) 301 to 304 realized by a microcomputer respectively communicate through communication paths 201 to 204. Connected through.

The robot main controller 100 calculates a control amount to drive each servomotor (not shown) to drive the control target based on the control target situation and the control command, and the communication paths 201 to 204
To the corresponding servo drivers 301-304.
Each servo driver receives the control amount from the main control unit 100 and directly drives and controls the corresponding servo motor. Each servo motor drives an arm of each axis of the industrial robot.

A conventional processing method in such a digital motor control device is shown in FIGS.
This will be described with reference to (e).

FIG. 12 is a flowchart showing the processing operation of the conventional robot main controller 100. First, the robot main controller
Commands to control each axis of the industrial robot, for example, starting and ending points of movement based on teaching content, and drive the arm for each axis according to the current situation of the controlled object, for example, position, angle, etc. The movement amount is calculated (step S051). Then, based on the above-mentioned entire movement amount, a movement amount (unit control amount) for moving each axis smoothly at a constant period τ1, for example, τ1 = 1 ms as shown in FIG. a1 to a4 are calculated (step S052). The robot main controller 100 sequentially transmits the unit control amounts a1 to a4 to the corresponding servo drivers within the period τ1 (steps S053 to S056).

On the other hand, as shown in FIG. 13, each servo driver, for example, the first servo driver 301 transmits the unit control amount a1 calculated by the robot main control unit 100 and transmitted from the robot main control unit 100 to a communication path. Received via 201 (Step S
061), calculates the data necessary to control the servo motor from the received data a1 using its internal constants (step
In step S062, the corresponding servomotor is drive-controlled based on the calculated data (step S063).

The above processing operation is performed at a constant period τ1, as shown in FIGS. 14 (a) to 14 (e). Therefore, the control amount transmission timing transmitted from the robot main control unit 100 to each of the servo drivers 301 to 304 is a fixed period τ1, and the control period of each servo motor is also the above period τ1. This period τ1 is also a control period for smoothly driving the control target in consideration of the inertia of the servomotor and the arm. In other words, in such a digital servo control system, control is performed at a sampling period. However, considering the inertia of the servo motor and the arm, the sampling period for smoothly driving the servo motor becomes the communication period. I have.

[Problems to be solved by the invention]

As is clear from FIGS. 14 (a) to (e), when the robot main control unit calculates the above control amount at a constant period τ1, and communicates the unit control amount to each servo driver at that period, The communication time τ11 for each servo driver is the period τ1
And a problem that the time τ12 for performing other processing in the cycle τ1 is not sufficient. For this reason, for example, when an attempt is made to perform more complicated control processing without further adding a microcomputer, a problem is encountered in that it is impossible to perform complicated control processing due to encountering a performance limit, or There is a problem that it is not possible to expand the control target such as increasing the control target axis.

The above problem is not limited to the industrial robot device, and is the same for a device similar to the above-described device for controlling a plurality of motors.

Therefore, the present invention provides a motor control device capable of effectively exerting the performance of an existing main control unit without adding new equipment and without substantially reducing the control characteristics of a motor such as a servomotor. The purpose is to provide.

[Means for solving the problem]

In order to solve the above-described problem, the present invention is to transmit control data for driving a motor for a plurality of control periods from a main control unit to a motor control unit, thereby reducing the number of times of communication and shortening the time occupied in communication. Each motor control unit converts control data for a plurality of control cycles into unit control data for each control cycle, and drives and controls the corresponding motor in its own motor control unit using the unit control data for each of multiple control cycles Based on the concept of doing.

That is, the present invention allows the main control unit and each motor control unit to share the role of calculating the control amount so that the communication time between the main control unit and each motor control unit is reduced. It is intended to control the plurality of motors comprehensively and smoothly while reducing the burden on the communication of the main control unit while maintaining the same control performance as the conventional one.

Therefore, even if the main control unit and each motor control unit share the task of calculating the control amount so that the time required for communication of the control amount is shortened, each motor control unit has the same control cycle as before. For example, the control cycle necessary for smoothly driving the control target in consideration of the inertia of the servo motor and the arm in the industrial robot can be secured, and the stability of the control system is maintained.

In addition, since the control cycle of each motor control unit is sufficiently short compared to the response of mechanisms such as arms and reduction gears, the main control unit controls the control amount for multiple cycles within the range that does not affect the entire control target. Are collectively calculated, so that the same control performance as that of the related art is maintained.

The motor control device according to the present invention comprises a main control unit shown in FIG.
10 and a plurality of motor control units 50. The main control unit 10
A control amount calculating means for calculating a control amount for a plurality of motor control cycles for each motor; and a control amount for each motor from the control amount calculating means at different communication timings among the plurality of motor control units. Corresponding motor control unit 50
And communication means 30 for transmitting the communication paths 42-44. Further, the motor control unit, for example, the motor control unit 52 shown in FIG. 2 should control the communication unit 522 for receiving the corresponding control amount from the communication unit 30 and control the motor control cycle in each motor control cycle based on the reception control amount. It has a unit control amount calculating unit 524 for calculating a unit control amount, and a control unit 524 for controlling driving of a corresponding motor based on the unit control amount in each motor control cycle.

[Action]

The operation of the motor control device described above will be described with reference to the attached flowchart.

 FIG. 3 shows a processing flowchart of the main control unit 10.

Step S001 The management means 12 of the main controller 10 determines whether or not the control amount calculation / communication timing has been reached. The control amount calculation / communication timing is periodic as shown in FIG. 5 (a). This cycle t10 corresponds to the conventional cycle τ1.
For example, if the conventional period τ1 is 1 ms, t10 is 1 ms.

Whether or not the control amount calculation / communication timing has been reached is determined, for example, by interruption of a timer (not shown) provided in the main control unit 10.

Steps S002 to S004 When the management means 12 identifies that the control amount calculation / communication timing has been reached, the management means 12 determines to which motor the control amount calculation / communication process corresponds to this timing.

Steps S003 to S004 In the case of the control amount calculation / communication timing for the first motor, the management means 12 activates the control amount calculation means 20. Thereby, the control amount calculating means 20 calculates a control amount to drive each motor during the next plurality of control cycles in the overall control of the control target (this calculation timing is shown in FIG. 5B). (Corresponding to the time t11 indicated by oblique lines).

The management means 12 activates the communication means 30. The communication means 30
The control amount for the first motor is transmitted to the first motor control unit 52 via the communication path 42 (time t12 indicated by a white line in FIG. 5B).

Here, as shown in FIGS. 5 (b) to (d), communication processing for each motor control unit is performed at different timings.

FIG. 4 shows a processing flowchart of the first motor control unit 52.

Steps S011 to S012 When there is a transmission request from the communication unit 30 of the main control unit 10,
The communication means 522 of the first motor control unit 52 is activated and receives the above-mentioned control data (FIG. 6 (c)).

Step S013 The unit control amount calculating unit 524 is activated by the data reception of the communication unit 522, and calculates the unit control amount per each control cycle from the above-mentioned control amount (FIG. 6 (d)).

As a method of calculating the unit control amount, for example, the reception control amount is averaged in each control cycle.

Steps S015 to S015 The control means 526 converts the unit control amount into a form required for motor control for each control cycle, and directly controls the drive of the motor. This drive control is performed for a plurality of control cycles corresponding to the control amounts for the plurality of control cycles sent from the main control unit 10 (FIG. 6 (e)).

 The same applies to other motor control units.

As is clear from FIGS. 5 (a) to 5 (d), the main control unit
10 collectively calculates the amount of movement of the motor in a plurality of control cycles for each motor control unit and sends it to the corresponding motor control unit, so that 1 control amount calculation / communication cycle t1
The communication time t12 occupying 0 is reduced. Therefore, the margin time t13 in one control amount calculation / communication cycle
Becomes larger.

On the other hand, as shown in FIG. 6 (e), each motor control unit controls the corresponding motor at a control cycle t10 similar to the conventional one.

〔Example〕

Hereinafter, embodiments of the present invention will be described by exemplifying an industrial robot. In this embodiment, the overall configuration of the motor control device of the present invention exemplifies the servo driver control device of FIG. 7 described above. However, the contents of the control and communication processing are different from those of the above-described conventional one, as described in detail below.

The robot control unit 100 shown in FIG. 7 is composed of a microcomputer, and includes a CPU, a ROM containing a program operating on the CPU, a RAM for temporarily storing data, and a communication device such as a synchronous communication device (USART). Become. The robot control unit 100 functions as the management unit 12, the control amount calculation unit 20, and the communication unit 30 in FIG. The servo driver of FIG. 7, for example, the servo driver 301 is also constituted by a microcomputer, and comprises a CPU, a ROM, a RAM, and a USART. This servo driver 301 communicates with the communication means 522 in FIG.
It functions as the unit control amount calculation means 534 and the control means 526.

FIGS. 8A and 8B show a flowchart of the processing operation of the robot control unit 100. FIG. FIG. 9 shows a flowchart of the processing operation of the first servo driver 301. First
The operation of the industrial robot controller according to the embodiment of the present invention will be described below with reference to FIGS.

Step S021 (FIG. 8 (a)) At time T1 in FIG. 10 (a), the robot control unit 100 determines, based on the teaching contents and the current state of each arm, for example, the position and angle, as the entire control target. Calculate the movement amount of the servo motor.

Steps S022 and S023 Next, the robot control unit 100 calculates a movement amount by which the servomotor driving each axis should be moved during a plurality of control cycles, in this example, four control cycles (step S02).
2). In this example, one control cycle is 1 ms. Therefore, four control periods are 4 ms.

Then, the value COU of a counter (actually, an address in RAM) for managing the communication timing to the servo drivers 301 to 304
The initial value of NT is set to "1" (step S023).

If the value of steps S024 to S026 COUNT is 1, the robot control unit 100 determines the calculated amount of movement for the first servomotor by the communication path 201.
Through the first servo driver 301. Then, COUNT is advanced by one.

The first servo driver 301 performs a process described below.

Step S041 (FIG. 9) The movement amount to move the first servomotor during four control cycles (4 ms) from the robot control unit 100 is received.

Steps S042 and S043 The movement amount a1 for moving the first servomotor during the 4 ms is the size b for moving the first servomotor every 1 ms in one control cycle.
1, ie, b1 = a1 / 4.

Then, for four control cycles, the first
Initialize the time management timer TIME for controlling the servo motors to 1.

Steps S044 to S048 Until the control cycle timer TIMER (address value in the RAM) reaches 5, that is, until the control cycle exceeds 4 control cycles, the data b1 is used for each control cycle (1 ms) using the internal conversion constant. The data for driving the first servomotor is calculated, and the value is used to control the first servomotor.
The timer TIMER is updated by adding 1 to TIMER.

Then, the servo driver 201 sets 1 ms to its own timer, and the process of step S044 is restarted after the elapse of 1 ms.

As a result, as shown in FIG. 10 (f), the first servo driver 201 internally stores the first servo driver 201 for four control cycles.
Control the servo motor.

On the other hand, in parallel with the processing of the first servo driver 301, the robot control unit 100 sends the second servo driver 302 to the second servo driver 302 at the next communication timing T2 after a period τ20 has elapsed from the first communication timing T1. , The amount of movement to move the second servomotor during the four control cycles is sent to the second servo driver 302 (FIG. 8B, steps S027 to S029,
(FIG. 10 (b)).

The processing operation of the second servo driver 302 is the same as the processing operation of the first servo driver.

Hereinafter, the corresponding movement amount is also sent to the third and fourth servo drivers based on the communication timing, and the movement amount received by each servomotor is converted into the movement amount per one control cycle. The corresponding servomotor is controlled in a time-sharing manner.

As shown in FIGS. 10 (a) to 10 (f), at time T1, one control cycle τ20 of the robot controller 100, that is, 1 ms
A time τ23 obtained by subtracting the sum of the control amount calculation time τ21 and the communication time τ22 from the above becomes a margin time. In the period from time T2 to T4, since the movement amount is not calculated, the time obtained by subtracting the communication time τ22 is a sufficient time. Therefore, this extra time can be used for other processing.

Each servo motor is controlled by each servo driver in each control cycle in the same manner as in the related art.

In the above embodiment, the movement amount of the four servomotors for driving the four-axis arm is calculated every four control periods τ2 (FIG. 10), and communication is performed every one control period τ20. The embodiment of the present invention is not limited to such a fixed period. For example, even if the control is basically performed in four control cycles, a certain servo motor may not be controlled under certain conditions.
There may be a case where driving at a constant speed may be performed during the control cycle. Further, there is a case where a certain servomotor is required to be driven at a constant speed for exactly four control cycles under certain conditions. In order to cope with such a state, the robot control unit 100 calculates the moving amount in step S021 of FIG.
Under the above-mentioned conditions, the moving amount for eight control periods is transmitted collectively to a certain servo driver at a certain time, and the moving amount is transmitted every four control periods to another servo driver. To do. Therefore, the robot controller
As shown in FIG. 11, not only the movement amount but also control cycle data corresponding to the movement amount is transmitted from 100 to each servo driver. The servo driver averages the amount of movement received in this control cycle data, calculates the amount of movement per control cycle (unit movement), and controls the servo motor with the unit movement during the given control cycle. To do. Also in this case, the communication time is reduced.

〔The invention's effect〕

As described above, according to the present invention, the control amounts for a plurality of control cycles are collectively calculated in consideration of the inertia of the motor and the control target driven by the motor, and In other words, the communication timing can be reduced, and the unit control in each control cycle can be performed by each motor control unit, so that the communication time can be reduced, and the time corresponding to the reduced time can be used for other processing. This has the effect.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main control unit in the motor control device of the present invention, FIG. 2 is a block diagram of a motor control unit in the motor control device of the present invention, FIG. 3 is a processing flowchart of the main control unit of the present invention, FIG. 4 is a processing flowchart of the motor control unit of the present invention, FIGS. 5 (a) to (d) are operation timing diagrams of the main control unit of the present invention, and FIGS. 6 (a) to (e) are the present invention. FIG. 7 is a configuration diagram of a servo motor control device to which the present invention is applied, and FIGS. 8A and 8B are robot control units of the embodiment of the present invention shown in FIG. 9 is an operation processing flowchart of the servo driver according to the embodiment of the present invention in FIG. 7, FIG. 10 (a) to FIG. 10 (f) are operation timing diagrams of the embodiment of the present invention, FIG. Is the robot controller in another embodiment of the present invention? Diagram of data format sent to servo driver, FIG. 12 is a processing flowchart of a conventional robot controller, FIG. 13 is a processing flowchart of a conventional servo driver, and FIGS. 14 (a) to (e) are conventional operation timings FIG. (Explanation of symbols) 10: Main control unit, 12: Management means, 20, 22 to 24: Control amount calculation means, 30, 32 to 34: Communication means, 50, 52 to 54: Motor control unit , 522 ... communication means, 524 ... unit control amount calculation means, 526 ... control means.

Claims (2)

(57) [Claims] A plurality of motor control units for periodically controlling the plurality of motors, and a control amount calculated for each motor, and the calculated control amount is periodically transmitted to a corresponding motor control unit via a communication path. A motor control device comprising a main control unit for controlling the plurality of motors by transmitting the control signals to the motors, wherein the main control unit calculates a control amount to control the motors during a plurality of control cycles for each motor. Control amount calculating means for transmitting the control amount for each motor from the control amount calculating means to the corresponding motor control unit at a different communication timing via a communication path. A communication unit for receiving a corresponding control amount from the communication unit of the main control unit; and a unit control amount for controlling the corresponding motor in each control cycle from the received control amount. Position control amount calculating means and the motor controller, characterized in that it comprises a control means for driving and controlling the corresponding motor on the basis of the unit control amount for each control cycle. A plurality of motor control units for periodically controlling the plurality of motors, and a control amount calculated for each motor, and the calculated control amount is periodically transmitted to a corresponding motor control unit via a communication path. And controlling the motors using the main control unit that controls the plurality of motors comprehensively by controlling the motors during a plurality of control cycles for each motor. Calculating the control amount to be calculated; transmitting the calculated control amount for each motor to the corresponding motor control unit at a different communication timing via a communication path; receiving the control amount and receiving the received control amount A unit control amount calculating means for calculating a unit control amount for controlling the corresponding motor in each control cycle, and driving control of the corresponding motor based on the unit control amount in each control cycle A motor control method comprising: