JPH11191011A - Robot control unit and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a line process time by distinguishing controls requiring accurate positioning from these not requiring it in a series of operations. SOLUTION: When a control flag is off in steps S5 and S9, it is determined whether or not deviation of the current position of an X or Z axis from a target position corresponding to an operation command is less than predetermined by referring to a detection signal representing the current position, and when the deviation is less than the set value, a position confirmation signal for confirming that the target position reached a deviation less than the specific set value is generated and outputted to a CPU together with a command processing end signal. When the control flag is on in the step S5, on the other hand, the command process is ended once the remaining movement quantity corresponding to the operation command decreases below predetermined before the above position confirmation signal is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a robot control device for controlling a moving position of a robot arm in a robot that drives at least one axis of a robot arm by a servomotor, and a control method thereof.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a robot, FIG. 4 is a diagram showing an operation example of the robot of FIG. 3, and FIG. 5 is a control circuit block diagram of the robot control device of FIG.

In FIG. 3, the robot is a portal type two-axis robot, and an X-axis arm 31 that moves horizontally, a Z-axis arm 32 that moves vertically, and a work provided at the tip of the Z-axis arm. Mechanism, a workpiece 34 gripped by the clamp mechanism 33, a first work mounting table 35, and a second work mounting table 36, and the X-axis arm 31, the Z-axis arm 32, Mechanism 3
The operation of 3 is controlled by the robot controller 37.

Here, an operation of transferring the work 34 from the work mounting table 35 to the work mounting table 36 will be described with reference to FIG.

As shown in FIG. 4, if position A is the position of the work table 35, position D is the position of the work table 36, and the clamp mechanism 33 is stopped at position B, The position is position B → Z axis arm 3
2 moves down to position A → position A → clamps work 34 →
Move Z-axis arm 32 to position B → Position B → Move X-axis arm 31 to position C → Position C → Move Z-axis arm 32 to position D → Position D → Unclamp work 34 → Position Z-axis arm Ascend to C → Position C → Move X-axis arm to Position B
Is controlled by a series of operations of moving to position B.

Next, a control circuit configuration of the robot controller 37 will be described.

[0007] As shown in FIG.
Has an actuator control unit 51, and the CPU 40 outputs an operation signal to an arithmetic processing unit 52 of the control unit 51. The arithmetic processing unit 52 calculates the amount of movement of the X-axis or Z-axis arms 31, 32 based on the operation signal output from the CPU 40,
An operation control signal indicating the movement amount is output to the position loop processing units 53 and 58 as an operation command. The position loop processing units 53 and 58 and the speed loop processing units 54 and 59 output pulse signals corresponding to the operation control signals to the motors 56 and 61 via the current output units 55 and 60. Motors 56, 61
Drives the X-axis arm 31 and the Z-axis arm 32 according to the pulse signal. The motors 56 and 61 have encoders 57 and 62, respectively, and the position loop processing units 53 and 58 and the speed loop processing units 54 and 59 provide the current values of the X-axis or Z-axis arms 31 and 32 output from the encoders 57 and 62, respectively. The deviation between the target position and the current position according to the operation command from the detection signal representing the position is fed back to the arithmetic processing unit 52, and the motor 56 based on the operation command from the arithmetic processing unit 52 calculated according to this deviation. , 61 are feedback controlled.

Next, a control flow by the robot controller of FIG. 5 will be described with reference to FIG. 5 and FIG.

FIG. 6 is a flowchart showing an operation example of the robot control device of FIG. FIG. 7 is a diagram showing the response characteristics of the motor according to the control flow of FIG.

In FIG. 5 and FIG. 6, when the processing is started, in step S101, the arithmetic processing unit 52
The command output from 40 is received, and the initialization required for the operation control of the robot is executed. In step S102, the arithmetic processing unit 52 calculates the movement amount of the X-axis arm or the Z-axis arm. In step S103, the arithmetic processing unit 52 outputs an operation command to the position loop processing units 53 and 58 and the speed loop processing units 54 and 59. Step S104
Then, the position loop processing units 53 and 58 and the speed loop processing units 54 and 59 determine whether or not the operation command from the arithmetic processing unit 52 has been stopped. If the operation command is stopped in step S104 (YES), in step S105, the position loop processing units 53 and 58 and the speed loop processing unit 54
59 outputs the deviation between the target position and the current position according to the operation command from the detection signal indicating the current position of the X-axis or Z-axis arms 31 and 32 output from the encoders 57 and 62 to the arithmetic processing unit 52, The arithmetic processing unit 52 determines whether or not the deviation is equal to or less than a predetermined set value. If the deviation is equal to or smaller than the set value in step S105 (YES), a position confirmation signal for confirming that the current position of the arm has reached the target position with the deviation equal to or smaller than the predetermined set value is generated in step S106. In step S107, the command is output to the CPU 40 together with the command processing end signal.

FIG. 7 is a diagram for explaining the response characteristics of the robot based on the operation example of FIG.

The horizontal axis in FIG. 7 indicates time, and the vertical axis indicates the operating speed of the motor. In a series of operations in FIG. 6, the operation command from the arithmetic processing unit 52 is output in a trapezoidal shape with time. The actual operation of the motor shaft is temporally delayed with respect to the operation command.

[0013]

In the above conventional example, FIG.
After the movement from the position A to the position D shown in (1), accurate positional accuracy is required to switch the workpiece from the clamp to the unclamping. For this reason, it is not possible to shift to the next command process until the position confirmation signal is output.

However, position A → position B → position C → position D
, The positions B and C are passing points in the sky, so that the positions B and C need not be as accurate as the positions A and D.
If the operation control to C is performed until the position confirmation signal is output, there is a problem that the tact time is prolonged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to separate a control operation requiring accurate position accuracy from a control operation not requiring position accuracy in a series of operations to reduce the tact time. An object of the present invention is to provide a robot control device and a control method thereof that can be shortened.

[0016]

In order to solve the above-mentioned problems and achieve the object, a robot control device according to the present invention has the following arrangement. That is, in a robot having at least one-axis arm, a robot control device including a driving unit for moving the arm to a target position when the arm is moved, the robot control device for moving the arm to a target position with respect to the driving unit. Output means for outputting an operation signal, feedback means for detecting the amount of movement of the arm based on a detection signal output from the driving means, and feeding back the output to the output means; Determining means for determining whether the deviation has become equal to or less than a predetermined first set value; and stopping means for stopping output of the operation signal when the deviation has become equal to or less than the predetermined first set value;
In the case where the stopping means performs an operation according to a predetermined condition, the remaining movement amount of the arm according to the operation signal is equal to a predetermined second amount.
When the difference becomes equal to or smaller than the set value, the output of the operation signal is stopped before the judgment unit judges that the deviation has become equal to or smaller than a predetermined first set value.

The robot control method of the present invention has the following features. That is, in a robot having at least one axis arm, a driving unit for moving the arm to a target position when the arm is moved, and an operation signal for moving the arm to the target position is output to the driving unit. Output means, feedback means for detecting the amount of movement of the arm based on a detection signal output from the driving means, and feeding back the output to the output means; and a deviation between the current position and the target position of the arm being a predetermined value. A control method for a robot control device, comprising: a determination unit configured to determine whether the difference is equal to or smaller than a first set value; and a stop unit configured to stop outputting an operation signal when the deviation is equal to or smaller than a predetermined first set value. In the case of an operation according to a predetermined condition, if the remaining movement amount of the arm according to the operation signal becomes equal to or less than a predetermined second set value, the determination means Said deviation to control said stopping means to stop the output of the operation signal before it is determined that equal to or less than the first set value of the predetermined Ri.

[0018]

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

First, a control operation in the case where the robot shown in FIG. 3 is controlled by the robot controller shown in FIG. 5 will be described with reference to FIG. The configuration of the robot according to the present embodiment is the same as that shown in FIG. 3, and the robot control device according to the present embodiment is also the same as that shown in FIG.

FIG. 1 is a flowchart showing the control operation of the robot control device according to the embodiment of the present invention. FIG.
FIG. 3 is a diagram illustrating response characteristics of the robot as an operation result according to the control flow of FIG. 1.

As shown in FIGS. 3 to 5, when the clamp mechanism 33 is moved from position A to position B to position C to position D in order to transfer the work 34 from the work mounting table 35 to the work mounting table 36. In each operation, a command is output from the CPU 40 to the arithmetic processing unit 51. At this time, if the operation requires accurate position accuracy, the arithmetic processing unit 52 turns off the control flag (sets it to “0”) at the time of transition to the operation. If the operation is not performed, the control flag is turned on (set to "1") at the time of transition to the operation. That is, the control flag is
Regarding the contents of the control operation at 40, it is an index for separating operation control requiring accurate position accuracy from control operation not requiring position accuracy.

In the CPU 40, if the control flag is turned off, the arithmetic processing unit 52 responds to the operation command from the detection signals output from the encoders 57 and 62 and representing the current position of the X-axis or Z-axis arms 31 and 32. It is determined whether the deviation between the target position and the current position is equal to or less than a predetermined set value, and if the deviation is equal to or less than the set value, the current position of the arm becomes the target position with a deviation equal to or less than the predetermined set value. Then, a position confirmation signal for confirming the fact is generated and output to the CPU 40 together with the command processing end signal.

On the other hand, if the control flag is on, the CPU 40 determines that the deviation is equal to or less than the set value, and that the remaining moving amount according to the operation command is equal to or less than the predetermined set value before the position confirmation signal is output. At this point, the command processing ends. [When Positional Accuracy is Required] The movement from position B to position A or position C to position D in FIG. 4 involves clamping and unclamping of the work, and is an operation that requires accurate position accuracy. An operation example at this time will be described with reference to FIG.

As shown in FIG. 1, when the process is started,
In step S1, the arithmetic processing unit 52 receives an operation signal, a control flag, and a command from the CPU 40, and determines whether the previous command processing has been completed. Step S
If the previous command processing is completed in 1 (YE
S), and proceed to step S2. In step S2, the arithmetic processing unit 52 performs an initial setting necessary for the movement of the arm. In step S3, the movement amount of the arm is calculated. In step S4, an operation command is output to the position loop processing units 53 and 58 and the speed loop processing units 54 and 59.

In step S5, it is determined whether the control flag is on. If the control flag is ON in step S5 (YES), the operation in which accurate position accuracy is not required shown in steps S6 and S7 described later is executed. Step S5
If the control flag is off (NO), the process proceeds to step S8.

In step S8, the arithmetic processing section 52 repeatedly executes the operation from step S3 until the operation command is completed (feedback control). If the operation command has been completed in step S8 (YES), it is determined in step S9 whether or not the control flag is on. If the control flag is on in step S9 (YES), the operation returns to step S1 to execute the next command processing because the operation does not require accurate position accuracy. If the control flag is OFF in step S9 (NO), the process proceeds to step S10, where the position loop processing units 53 and 58 and the speed loop processing units 54 and 59
The deviation between the target position of the X-axis arm or the Z-axis arm and the current position is output to the arithmetic processing unit 52 from the pulse signals corresponding to the operation commands output to the current output units 55 and 60 and the detection signals from the encoders 57 and 62. The arithmetic processing unit 52 determines whether the deviation is equal to or less than a predetermined first set value. If the deviation is equal to or smaller than the first set value in step S10, (Y
ES), in step S11, a position confirmation signal for confirming that the movement destination of the arm has reached the target position with a deviation equal to or smaller than the first set value is generated. Output. [When position accuracy is not required] Position A → position B, position B → position C, position C → position B, position D → position C in FIG.
The movement to, which does not involve clamping and unclamping of the work, is an operation that does not require accurate positional accuracy. An operation example at this time will be described with reference to FIG.

In FIG. 1, the operations in steps S1 to S4 are the same. If the control flag is ON in step S5 (YES), the operation does not require accurate position accuracy. It is determined whether or not the remaining movement amount has become equal to or less than a predetermined second set value. If the remaining movement amount is equal to or less than the second set value in step S6 (NO), a command processing end signal is output to the CPU 40 in step S7. Thereby, the CP
U40 can shift to the next process.

In step S6, the remaining moving amount is equal to the second moving amount.
If the value is not equal to or smaller than the set value (YES), the process proceeds to step S8. In step S8, it is determined that the operation command in the driver unit 51 has not ended (NO in step S8). The processing from S3 is repeatedly executed.

As shown in FIG. 2, in an operation in which accurate position accuracy is not required, if the remaining movement amount according to the operation command becomes equal to or less than a second predetermined value, the command processing is terminated. Therefore, it is not necessary to wait until a position confirmation signal for confirming that the current position has reached the target position is output as in the related art, and the next command from the CPU 40 can be received t2 seconds earlier. And CP
U40 can shift to the next command processing at an early stage, and can execute another command processing while the motor is being driven. In the arithmetic processing unit 52, the CPU operates until the current operation command is completed.
The next command received from 40 is not executed, the next command is in a standby state, and the next command processing is executed after the current operation command is completed.

In the above-described operation example, there are four operations that do not require accurate position accuracy: position A → position B, position B → position C, position C → position B, and position D → position C. CPU
In the case of 40, another processing can be performed while the motor is being driven. Therefore, if the processing time is t1, the tact time can be reduced by 4 × (t1 + t2) seconds.

According to the embodiment described above, in the operation requiring accurate position accuracy, the control flag is set to OFF in advance, and the position confirmation signal indicating that the current position has reached the target position is output. The next operation command is executed from the following, and for the operation that does not require accurate position accuracy, the control flag is set on in advance, the operation command is executed without waiting for the position confirmation signal, and the remaining movement amount is determined in advance. If the amount becomes equal to or less than the set amount, the command processing based on the operation command can be terminated and the next command processing can be executed, so that the tact time can be reduced.

It should be noted that the present invention is applicable to modifications or changes of the above embodiment without departing from the spirit thereof.

For example, in the present embodiment, it goes without saying that the present invention can be applied to other types of robots that have described the pick-up operation of the portal type two-axis robot.

[0034]

Another embodiment of the present invention is to provide a storage medium storing a program code of software for realizing the control function of the robot control apparatus of the above-described embodiment to a system or apparatus, and to provide a computer (or computer) of the system or apparatus. It goes without saying that a CPU or an MPU may read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided on a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. Is stored in the storage medium.

[0040]

As described above, according to the present invention,
Takt time can be reduced.

[0041]

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an operation example of a robot according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating response characteristics of the robot according to the embodiment of the present invention.

FIG. 3 is a configuration diagram of a robot.

FIG. 4 is a diagram illustrating an operation example of the robot in FIG. 3;

FIG. 5 is a control circuit block diagram of the robot control device of FIG. 3;

FIG. 6 is a flowchart illustrating an operation example of a conventional robot.

FIG. 7 is a diagram illustrating response characteristics of a conventional robot.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 31 ... X-axis arm 32 ... Z-axis arm 33 ... Clamp mechanism 34 ... Work 35 ... First work mounting table 36 ... Second work mounting table 37 ... Robot control device 51 ... Driver unit 52 ... Operation processing units 53 and 58 ... Position loop processing units 54 and 59 ... Speed loop processing units 55 and 60 ... Current output units 56 and 61 ... Motors 57 and 62 ... Encoders

Claims (8)

[Claims] 1. A robot controller having at least one axis of an arm, comprising: a drive unit for moving the arm to a target position when the arm is moved, wherein the arm is moved to a target position with respect to the drive unit. Output means for outputting an operation signal for causing the arm to move, an amount of movement of the arm detected by a detection signal output from the driving means, feedback means for feeding back to the output means, a current position of the arm and a target The deviation from the position is the first
Determining means for determining whether the difference has become equal to or less than a set value; and stopping means for stopping the output of the operation signal when the deviation has become equal to or less than a predetermined first set value. In the case of the corresponding operation, the remaining movement amount of the arm according to the operation signal is equal to a predetermined second
If the difference is equal to or smaller than a set value, the robot control device stops outputting the operation signal before the judgment unit judges that the deviation has become equal to or smaller than a predetermined first set value. 2. The robot control device according to claim 1, wherein the predetermined condition is a case where a preset flag is set to ON. 3. The operation according to claim 2, wherein the flag is set to on when the operation does not require accurate position accuracy, and is set to off when the operation requires accurate position accuracy. 4. The robot control device according to item 1. 4. The apparatus according to claim 1, wherein the output unit outputs an operation signal related to a next operation after the output of the operation signal is stopped by the stop unit. A robot controller as described. 5. A robot having at least one axis arm, a driving unit for moving the arm to a target position when the arm is moved, and an operation signal for moving the arm to the target position with respect to the driving unit. Output means, and a detection signal output from the driving means,
Feedback means for detecting the amount of movement of the arm and feeding back to the output means; and determining means for determining whether a deviation between a current position and a target position of the arm is equal to or less than a predetermined first set value. The deviation is a predetermined first
A control method for a robot control device, comprising: a stop unit that stops output of an operation signal when the operation signal becomes equal to or less than a set value. If the amount becomes equal to or less than a predetermined second set value, the stop means stops outputting the operation signal before the determination means determines that the deviation has become equal to or less than the predetermined first set value. A control method characterized by controlling the following. 6. The control method according to claim 5, wherein the predetermined condition is a case where a preset flag is set to ON. 7. The method according to claim 6, wherein the flag is set to on when the operation does not require accurate position accuracy, and is set to off when the operation requires accurate position accuracy. The control method described in 1. 8. The apparatus according to claim 5, wherein the output means outputs an operation signal relating to a next operation after the output of the operation signal is stopped by the stop means. The control method described.