JPH09225870A - Robot controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cancel a torque which acts upon to a first arm by reaction due to the acceleration and deceleration of a second arm before the first arm receives an influence by this torque. SOLUTION: In a robot having a first arm and a second arm, when the second arm is turned, a load fluctuation calculating part 23 calculates a load fluctuation torque command signal Ht from the torque command signal of the second arm and an angle θ between the first and second arms, and outputs this signal Ht to a speed controlling part 19 composing the controller 10 of the first arm. The speed controlling part 19 corrects a torque command signal St on the basis of the load fluctuation torque command signal Ht.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller such as an industrial robot for performing assembly work or palletizing work.

[0002]

2. Description of the Related Art For example, in an industrial robot, the movement of a plurality of arms from a current position to a target position is automatically repeated by a control device such as a microcomputer. At this time, the control device that controls the motor that is the drive source of each arm is configured to include a storage unit, a calculation unit, a position control unit, and the like in which the target position and parameters related to each arm are stored in advance.

The computing unit obtains the movement amount of each arm from the current position to the target position, determines the speed pattern of each arm from the movement amount, the set acceleration / deceleration time, and the set speed, and the speed pattern thereof. Then, the target position at each sampling time is output as a position command signal. Then, in the position control unit, a position deviation is obtained from the position command signal of each arm and the position feedback signal of each arm, and a speed command signal is created by multiplying this by a position loop gain. It outputs to the servo driver to drive the motor.

Therefore, in the case of the above configuration, when a disturbance such as load fluctuation occurs and the rotation amount of the motor of each arm decreases or increases, the position feedback signal of each arm decreases or increases, and as a result, the speed command signal. Is increased or decreased to accelerate or decelerate the motor to match the target position at each sampling time.

[0005]

In the case of a horizontal turning robot having, for example, two arms connected to each other, when the motor of one arm rotates and the arm turns, the acceleration / deceleration of the arm causes A torque acts on the other arm by the reaction force. This torque causes a load fluctuation, that is, a disturbance to change the rotation amount of the motor of the other arm, and the position of the arm changes from the target position. Conventionally, such a variation from the target position of the arm is also generated as described above based on the position deviation between the feedback signal of each arm and the position command signal, and the speed command signal is generated by the servo driver. It was configured to output to and drive the motor. However, as described above, in the case of the control in which the position variation is corrected after the disturbance occurs and the position variation is corrected, there is a drawback that the positioning takes time.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make a first rotation about a first axis.
Arm, a second arm that is provided on the first arm, and rotates about a second axis that is non-orthogonal to the first axis, and a first motor that drives the first arm. ,
A robot having a second motor for driving the second arm is controlled, and a torque acting on the first arm by a reaction force due to acceleration / deceleration of the second arm is controlled by the torque. It is an object of the present invention to provide a robot controller that cancels one arm before it is affected.

[0007]

In order to achieve the above object, a robot controller according to a first aspect of the present invention has a first arm which pivots about a first axis and a first arm. A second arm that is provided and rotates about a second axis that is non-orthogonal to the first axis, a first motor that drives the first arm, and a first motor that drives the second arm. A robot having a second motor is controlled, and when the second arm is accelerated or decelerated, a torque acting on the first arm is calculated by a reaction force due to the acceleration or deceleration of the second arm. A correction means for correcting the output torque of the first motor based on the torque is provided.

In this case, the correcting means acts on the first arm based on the torque command signal given to the second motor and the angle between the first and second arms when the second arm is accelerated or decelerated. The torque may be calculated (Claim 2), or the correction means may set the angle between the current value flowing through the second motor and the first and second arms during acceleration / deceleration of the second arm. Alternatively, the torque acting on the first arm may be calculated based on the above (Claim 3). Also,
You may make it provide the selection means which selects whether to correct | amend the output torque of a 1st motor by a correction means (Claim 4).

[0009]

FIG. 1 shows a first embodiment of the present invention.
It will be described with reference to FIGS. First, FIG. 3 schematically shows a horizontal turning robot which is an industrial robot according to this embodiment. In the robot 1, a base 2 is fixed and installed on an installation surface G, and a column 3 is erected on the base 2. A first shaft 4 extending in a direction perpendicular to the installation surface G is provided in a substantially central portion of the support column 3, and a first arm is provided at a tip portion of the shaft 3 protruding from an upper end surface of the support column. 5 is fitted. Therefore, the first arm 5 can be horizontally swung around the first shaft 4.

A second shaft 6 extending in the direction perpendicular to the installation surface G is provided at the tip of the first arm 5, and the shaft 5 projecting from the upper surface of the first arm 5 is provided. The second arm 7 is fitted to the tip of the. Therefore, the second
The arm 7 is rotatable about the second shaft 6 in the horizontal direction. An elevating arm 8 which is vertically moved by a ball screw is vertically provided at the tip of the second arm 7, and a wrist 9 is horizontally pivotally provided at the lower end of the elevating arm 8.

Next, the robot controller will be described with reference to FIGS. 1 and 2. FIG. 1 shows a part of the robot control device according to the present invention that controls the first arm 5 on the base 2 side. The control device 10 is a motor for rotating the first arm 5. A servo driver 12 as a driving unit for driving (hereinafter referred to as a first motor) 11 and a position control device 13 including a microcomputer or the like are included. Further, the rotation speed and the rotation position of the first motor 11 are respectively detected by a position detector 14 such as a rotary encoder and a speed detector 15 such as a tachogenerator.

The position control device 13 comprises a storage unit 16, a calculation unit 17, and a position control unit 18. The storage unit 16
The teaching position data (data such as the take-out position and the carry-out position of the work) and the operation program described in, for example, a robot language are stored in the. The calculation unit 17
Analyzes the operation program, obtains the movement amount of the first arm 5 at each sampling time, and outputs the position command signal Sp.
Is output. Then, the position control unit 18 compares the position command signal Sp with the position feedback signal Pfb input from the position detector 14 to obtain a position deviation, and a speed command signal Sv corresponding to the position deviation. Is generated and output to the servo driver 12.

The servo driver 12 includes a speed controller 1
9, current control unit 20, power control unit 21, and current detector 2
2 is provided. Of these, the speed control unit 19
Calculates the deviation between the speed command signal Sv from the position controller 19 and the speed feedback signal Vfb from the speed detector 15, generates a torque command signal St according to the deviation, and causes the current controller 20 to generate the torque command signal St. It is designed to output.
Further, the current control unit 20 uses the torque command signal St.
And a deviation from the current value I actually flowing through the first motor 11 detected by the current detector 22 is obtained, and a current command signal Si corresponding to the deviation is output to the power control unit 21 for power control. The section 21 is adapted to flow a current corresponding to the current command signal Si to the first motor 11.

Thus, the first motor 11 is operated by the arithmetic unit 1
It will be turned by the amount of movement obtained by 7.
Therefore, the first arm 5 of the robot 1 is moved from the current position to the target position. In this case, the calculation unit 1
When moving the first arm 5, the moving speed pattern 7 is set by accelerating the moving speed pattern from a speed of 0 to a set speed V at a set acceleration time ta as shown in FIG. 5A, for example. A trapezoidal pattern is set in which the vehicle is moved at a constant speed V and then decelerated to a speed of 0 at the set deceleration time td. Since the position of the first arm 5 with the passage of time is obtained by integrating the above velocity,
As shown in (b), the target position (position command signal Sp) at each sampling time is obtained. By performing the position control according to the position command signal Sp, the first arm 5 makes a smooth turning motion.

Although the control device 10 for the first motor 11 has been described here, the same applies to a motor for rotating the second arm 7 and the third arm 9 and a motor for vertically moving the elevating arm 8. Control is performed, and the description thereof will be omitted.

Now, as described above, the second arm 7
Is configured such that its shaft 6 is provided on the tip side of the first arm 5 and the first shaft 4 and the second shaft 6 are non-orthogonal, in this case, parallel. As shown in FIG. 4, when the second arm 7 turns in the direction of arrow A, a torque acts on the first arm 5 by the reaction force P against the inertial force F generated by the acceleration / deceleration of the second arm 7. . Then, this torque becomes a load fluctuation, and the first arm 5
Will be turned in the direction of arrow B. In addition, in FIG. 4, F,
P indicates the case when the second arm 7 is being accelerated.

Therefore, in this embodiment, when the second arm 7 turns, the torque acting on the first arm 5 by the reaction force P due to the acceleration / deceleration of the second arm 7 is calculated, and the torque is calculated. A load fluctuation calculation unit 23 is provided as a correction value calculation unit that outputs a load fluctuation torque command signal Ht for canceling to the speed control unit 19. With this,
When the load fluctuation torque command signal Ht is input, the speed control unit 19 adds this signal to the torque command signal St and the speed feedback signal Vfb and outputs it. Therefore, the speed control unit 19 and the load variation calculation unit 23 function as the correction means of the present invention.

The reaction force P has the same magnitude as the inertial force F generated in the second arm 7 by the acceleration / deceleration of the second arm 7, and the inertial force F drives the second arm 7 in the second direction. In this embodiment, the torque of the second motor is calculated on the basis of the torque command signal of the second motor because it is proportional to the torque of the motor. Further, since a torque acts on the first arm 5 due to the orthogonal component Pv of the reaction force P with the first arm 5, the first arm 5 and the second arm 7
The angle θ between and is calculated, and the cosine (cos θ) of the angle θ
Is multiplied by the torque command signal of the second motor.

Specifically, as shown in FIG. 2, the load fluctuation calculating section 23 is provided with the rotational position of the second motor for driving the position detector 14 of the first motor 11 and the second arm 7. A position detector (second position detector) 24 for detecting is connected to the position feedback signals Pfb and Pf, respectively.
b ′ is input, and the angle θ between the first and second arms 5 and 7 is calculated from these position feedback signals Pfb and Pfb ′. Further, a speed control unit (second speed control unit) 25 of the second motor is connected to the load variation calculation unit 23 so that the torque command signal St 'is input.

Then, the load variation calculation unit 2 is added to the product of the torque command signal St 'of the second motor and the cosine (cos θ) of the angle θ between the first arm 5 and the second arm 7.
3 is multiplied by a pre-stored proportional constant to create a load fluctuation torque command signal Ht.

Next, the operation of the above configuration will be described. Now, consider a case where the second arm 7 provided on the tip side of the first arm 5 on the base 2 side turns. Second
As described above, the arm 7 is subjected to feedback control by a control device (not shown), and is rotated by the amount of movement obtained by the calculation unit.
The second arm 7 automatically performs, for example, palletizing work by performing a predetermined turning motion. At this time, in the control device for the second motor, the torque command signal St ′ from the speed control unit 25 is output to the current control unit (not shown) and the load variation calculation of the control device 10 for the first motor 11 is performed. It is output to the unit 23.

Further, the position fluctuation signals Pfb and Pfb 'are inputted from the first and second position detectors 14 and 24 to the load fluctuation calculating section 23, and the load fluctuation calculating section 23 is connected between the first and second arms 5 and 7. The angle θ is determined. The load fluctuation torque command signal Ht is calculated by multiplying the cosine of the angle θ by the above-mentioned torque command signal St ′ and further multiplying it by a proportional constant stored in advance. Then, the load fluctuation torque command signal Ht is input to the speed control unit 19 of the first motor 11, and the torque command signal St is corrected.

According to this embodiment as described above, the first motor 1 for driving the first arm 5 provided on the base 2 side is provided.
When the second arm 7 makes a turning motion in the control of No. 1, the torque command signal St ′ is sent from the speed control unit 25 of the second motor to the load variation calculation unit 23 of the first arm 5.
Configured to be output to. Then, the load fluctuation calculation unit 23 calculates the load fluctuation torque command signal Ht from the torque command signal St ′ and the angle θ between the first and second arms 5 and 7, and outputs the load fluctuation torque command signal Ht to the speed control unit 19. The speed control unit 19 determines the first motor 11 based on the signal Ht.
The torque command signal St is corrected.

Therefore, when the second arm 7 turns, the torque acting on the first arm 5 is obtained by the reaction force P due to the acceleration / deceleration of the arm 7, and the torque command signal St of the first motor 11 is obtained. Since the correction is performed, the torque command signal St is corrected after the change in the rotation speed of the first motor 11 caused by the acceleration / deceleration of the second arm 7 is detected. The time required for positioning can be shortened.

FIG. 6 shows a second embodiment of the present invention. The difference from the first embodiment is that when the second arm 7 is accelerated or decelerated, the reaction caused by the acceleration or deceleration of the second arm 7 is reversed. The correction value of the torque acting on the first arm 5 by the force, that is, the load fluctuation torque command signal Ht, is set to the current value I ′ flowing through the second motor during acceleration / deceleration of the second arm 7 and the first and second values.
It is configured so that it is obtained based on the angle θ between the arms 5 and 7.

That is, in the present embodiment, the load fluctuation calculating section 31
Include position detectors 14, 24 for the first and second motors.
And a current detector 32 that detects the value I ′ of the current supplied to the second motor is connected. Then, the cosine of the angle θ between the arms 5 and 7 obtained based on the position feedback signals Pfb and Pfb ′ input from the position detectors 14 and 24 of the first and second motors and the second motor. The load fluctuation torque command signal H is calculated by multiplying the product of the current value I ′ and the coefficient stored in the load calculator 31 in advance.
That is, t is required.

Therefore, in this embodiment as well, as in the first embodiment, the torque acting on the first arm 5 by the reaction force P due to the acceleration / deceleration of the second arm 7 is applied to the second arm 7. Since the torque command signal St of the motor 11 of the first arm 5 is corrected at the time of acceleration / deceleration, the time required for positioning can be shortened.

In each of the above embodiments, the torque command signal St of the first motor 11 is unconditionally corrected when the second arm 7 is accelerated / decelerated. However, the torque of the first motor 11 is corrected. For example, a switch may be provided as a selection unit that selects whether or not to correct the command signal St, and the correction may be performed when the switch is turned on.

Further, the present invention is not limited to the above-mentioned embodiment, and for example, each axis of the first and second arms connected to each other, such as a horizontal turning robot, an articulated robot, etc. Can be widely applied to those that are non-orthogonal. Further, the robot is not limited to one having only one corresponding to the first arm 5 and one corresponding to the second arm 7,
There may be a plurality of arms having a relationship of the first and second arms.

Further, the position detector 14 and the speed detector 15
Functions as position detecting means and speed detecting means for detecting the swing position and swing speed of the arm based on the rotation position and rotation speed of the motor. This is replaced by a sensor for directly detecting the swing position and swing speed of the arm. May be.

[0031]

As is apparent from the above description, according to the robot controller of the present invention, when the second arm is accelerated or decelerated, the correction means causes the reaction force due to the acceleration or deceleration of the first arm Calculate the torque acting on the 1st arm,
Since the output torque of the first motor is corrected,
The time required for positioning can be shortened without unnecessary movement of each arm.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention and is a functional block diagram showing an overall configuration of a robot controller.

FIG. 2 is a functional block diagram of a load fluctuation calculation unit.

FIG. 3 is a schematic diagram showing the overall configuration of a robot body.

FIG. 4 is a plan view of the robot body

FIG. 5: Speed command signal from current position to target position (a)
And a diagram showing a pattern of the position command signal (b)

FIG. 6 is a view corresponding to FIG. 2 showing a second embodiment of the present invention.

[Explanation of symbols]

1 is a robot, 4 is a first axis, 5 is a first arm, 6 is a second axis, 7 is a second arm, 10 is a controller, 11 is a first motor, 19 is a speed controller ( Correction means), 23,
Reference numeral 31 denotes a load fluctuation calculation unit (correction means).

Claims (4)

[Claims] 1. A first arm that swivels about a first axis, and a second arm that swivels about a second axis that is provided on the first arm and is non-orthogonal to the first axis. Controlling a robot having an arm, a first motor for driving the first arm, and a second motor for driving the second arm, the acceleration / deceleration of the second arm Sometimes, a correction means is provided for calculating the torque acting on the first arm by the reaction force due to the acceleration / deceleration of the second arm, and correcting the output torque of the first motor based on this torque. Characteristic robot controller. 2. The torque acting on the first arm based on the torque command signal given to the second motor and the angle between the first and second arms when the second arm is accelerated or decelerated. The robot controller according to claim 1, wherein 3. The correction means calculates a torque acting on the first arm based on a value of a current flowing through the second motor and an angle between the first and second arms during acceleration / deceleration of the second arm. The robot controller according to claim 1, wherein: 4. The robot controller according to claim 2, further comprising a selection unit that selects whether or not the output torque of the first motor is corrected by the correction unit.