JPH11143521A - Industrial robot controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable one of shafts to operate at its highest velocity in an operating command generation cycle by setting the highest allowable velocity of every shaft to a designated velocity parameter. SOLUTION: When an interpolation operation is started, the teaching data outputted from a teaching data storage part 11 undergo the interpolation operation via an interpolation operation part 12, an inverse conversion part 14 and a segment data production/output part 15. Thus, the segment data are produced. The part 12 multiplies the teaching data by the velocity ratio of a velocity ratio store area 13 to control the velocity in each sampling cycle. A correction value operation part 17 calculates the correction value of every shaft by dividing each shaft designated velocity parameter of a shaft designated velocity parameter storage part 18 by the segment data and then selects the least correction value of every shaft. Then a velocity ratio operation part 19 performs an operation to decide the value obtained by multiplying the said least correction value by the velocity ratio of the area 13 as the new velocity ratio of the area 13. Thus, the next segment data are produced based on the said new velocity ratio of the area 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an industrial robot. More specifically, the present invention relates to a control device for operating any one of control axes with a parameter of a designated speed at the timing of outputting an operation command for each axis. TECHNICAL FIELD The present invention relates to a control device for an industrial robot having an interpolation calculation control function capable of performing interpolation.

[0002]

2. Description of the Related Art In many articulated robots, each joint is constituted by a rotating mechanism. In this case, as shown in FIG. 2, the control of the interpolation operation such as a straight line or an arc from a predetermined position to a predetermined position, including the posture, is performed only by the rotation of each joint angle. That is, the teaching position stored in the teaching data storage unit 21 is calculated by the interpolation calculation unit 22 in consideration of the operation speed so as to form a locus such as a straight line or an arc, and a target position and orientation for each sampling cycle are calculated. The inverse transformation unit 23 performs coordinate transformation (inverse transformation) on the target position and orientation in the orthogonal coordinate system into the joint coordinate system, and finally, the segment data creation output unit 24 calculates the difference (segment) from the joint coordinate data for the previous target position. (Referred to as “data”), and outputs the generated data to the servo drive system 25 to realize the interpolation operation.

The basic equation of the interpolation operation is shown in equation (1). P (k) = Ps + (k / N) × (Pe−Ps) (1) where Ps is a vector indicating the start point position, Pe is a vector indicating the end point position, and P (k) is Ps. And Pe represents an arbitrary position between Ps and Pe, and N is the number of times of sampling required when moving from Ps to Pe at a specified operation speed, and is obtained from the operation speed, the sampling period, and the moving distance. k is an integer and k
By adding 1 from 0 to N, that is, (1 / N) × (Pe−Ps) for each sampling period.
Is output, P (k) is shifted from the start point Ps to the end point Ps.
The operation speed changes up to e at the specified operation speed. As described above, conventionally, it was an object to generate an operation command while maintaining a specified speed. However, recently, there is a demand that the trajectory operates in a linear trajectory or an arc trajectory, and operates in a shortest moving time. In this case, in the related art, even if the designated speed is greatly increased, the operation may become inoperable beyond the maximum speed of each axis as shown in FIG. 3B. In order to avoid this inoperability, work such as reducing the designated speed is performed, but this adjustment is very difficult.

Japanese Patent No. 2560283 proposes a trajectory control method for a robot that can smoothly pass a singular point without departing from a given trajectory. This includes a step of detecting a singular point where the values of two predetermined joint axes are infinite, and a step of detecting the singular point when the singular point is detected.
The movement command of the joint axis at the base of one joint axis is fixed to the immediately preceding velocity, and the velocity of the other joint axis is calculated based on the velocity and the preset position and posture data of the tip of the wrist. A method comprising controlling a joint axis. Japanese Patent Application Laid-Open No. 6-324730 discloses a case where operation becomes impossible at a speed exceeding a maximum speed that may occur near a singular point or at another position in interpolation calculation of a straight line, an arc, or the like.
A robot control method that can be avoided easily and in a unified manner is disclosed. This is because, in an industrial robot having an interpolation function such as linear interpolation or circular interpolation, a means for storing each axis joint movement data for each sampling cycle output in the past and each joint data stored in the storage means for the next time. A means for estimating whether or not each axis joint movement data to be output exceeds the maximum joint speed, and a means for obtaining a correction coefficient when it exceeds the maximum joint velocity are provided. The interpolation operation is performed by multiplying the interpolation operation speed by the estimated coefficient so that the joint speed does not exceed the segment.

[0005]

However, in the control method disclosed in the above-mentioned Japanese Patent No. 2560283, the posture of the joint between the roots of the two joint axes is fixed at the speed immediately before it. There was a problem that you can not hold. Further, Japanese Patent Application Laid-Open No.
The control method disclosed in Japanese Patent Publication No. 30 is intended to reduce the speed so as not to cause segment over, so that when the operation time is controlled to be the shortest, the operation time becomes long. Therefore, the object of the present invention is to
In the cycle of generating operation commands, any axis can operate at the maximum speed, avoiding the case where operation cannot be performed beyond the maximum speed of each axis, and moving with linear, circular, etc. interpolation operations An object of the present invention is to provide a robot control device that can minimize the time.

[0006]

According to the present invention, there is provided an industrial robot control apparatus having an interpolation function such as linear interpolation or circular interpolation. A teaching data storage unit for storing teaching data for storing teaching data of a unit, a unit for storing a parameter of a designated speed of each axis, and, based on the teaching data,
An operation position is created, at this time, an interpolation operation unit that creates an operation position at a speed multiplied by a speed ratio, an inverse conversion unit that converts the operation position into an operation position of each axis, and an operation position of each axis. An operation command data creation / output unit that creates operation command data and outputs the operation command data to the servo drive system, and command data that instructs a parameter of a designated speed of each axis joint this time at the timing of outputting an operation command of each axis. A correction value calculation unit that calculates the correction value divided by the above for each axis, and the minimum value of the calculated correction value for each axis is selected, and the minimum value of the selected correction value and the speed ratio are multiplied. It is characterized by a control device including a speed ratio calculation unit that sets a value to a next speed ratio. As a result, at the time of interpolation, since any axis operates at the parameter value of the specified speed of each axis, the parameter of the specified speed of each axis is set to the maximum allowable speed of each axis, thereby shortening the movement time. It can work with.

[0007]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention. In the figure, 11 is a teaching data storage unit, 12 is an interpolation calculation unit, 13 is a speed ratio, 14 is an inverse conversion unit, 15 is a segment data creation output unit, 16 is a servo drive system, 17 is a correction value calculation unit, and 18 is each The axis designation speed parameter 19 is a speed ratio calculation unit. The present invention relates to a conventional interpolation operation unit 1
2, the speed ratio storage area 13, the correction value calculation unit 1
7, an axis-designated speed parameter storage unit 18 and a speed ratio calculation unit 19 are added. In this embodiment, when the interpolation operation is started, the teaching data output from the teaching data storage unit 11 is stored in the interpolation calculation unit 12 and the inverse conversion unit 1.
4. An interpolation operation is performed via the segment data creation / output unit 15 to create segment data. Interpolation operation unit 1
No. 2 allows the speed to be controlled for each sampling cycle by multiplying the teaching data by the speed ratio in the speed ratio storage area 13. Next, the correction value calculation unit 17 calculates a correction value for each axis by dividing each axis specification speed parameter in each axis specification speed parameter storage unit 18 by the segment data data. Then, the minimum value of the correction value for each axis is selected. Next, the speed ratio calculation unit 19 calculates a value obtained by multiplying the minimum value of the correction value calculated by the correction value calculation unit and the speed ratio of the speed ratio storage area 13 as the speed ratio of the speed ratio storage area 13. Do. Then, when the segment data is created next time, the operation is performed at the newly set speed ratio.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS This speed control device will be described by taking a robot having two axes of joints as an example. First, the speed ratio of the speed ratio storage area at the start of the operation is set to 1. It is assumed that each axis designated speed parameter is set to 100 corresponding to the maximum joint speed, and the segment data of the first axis is 80 this time and the segment data of the second axis is 60 this time. In the correction value calculation unit 20,
The correction value A1 for the first axis and the correction value A2 for the second axis are obtained by the following calculation. A1 = 100/80 = 1.25 A2 = 100/60 = 1.67 Then, the minimum value of A1 and A2 is selected, and the correction value A is set to 1.
25. The speed ratio calculation unit 21 multiplies the correction value A by the speed ratio of the speed ratio storage area to obtain a new speed ratio B.
Gives B = 1.25 × 1 = 1.25. The speed ratio B is equivalent to 1 in the conventional example, where K is an integer and 0 is added to N one by one. That is,
In the present invention, K is not an integer, but B is added instead of 1. When B is added instead of 1, the final value (total) does not become N. Therefore, the correction may be performed in the final calculation. By performing the above processing, as shown in FIG. 3A, the operation is performed at the speed of the designated speed parameter. Therefore, when the shaft speed is lower than the designated speed parameter, the speed is increased. Since the speed is suppressed at a fast position, the protection of the drive unit from overspeed can be easily performed. Further, it is needless to say that the present invention can be applied not only to linear interpolation but also to various interpolations.

[0009]

As described above, the present invention sets the maximum allowable speed of each axis in the designated speed parameter,
If the shaft speed is lower than the specified speed parameter, the speed can be increased to the maximum allowable speed, so the movement time is shortened. Conversely, if the shaft speed is higher than the specified speed parameter, the speed is reduced to the maximum allowable speed. Therefore, it is possible to avoid an inoperable state due to an overspeed of the driving unit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

FIG. 3 is a time chart showing an operation state of the present invention and a conventional example. 11 teaching data storage unit, 12 interpolation calculation unit, 13 speed ratio, 14 inverse conversion unit, 15 segment data creation output unit, 16 servo drive system, 17 correction value calculation unit, 1
8 Specified speed parameter for each axis, 19 Speed ratio calculator

Claims (1)

[Claims] 1. An industrial robot control device having an interpolation function such as linear interpolation or circular interpolation, comprising: a teaching data storage unit for storing teaching data for storing an interpolation command, an operating speed, and teaching data for each axis; Means for storing a parameter of a designated speed of each axis; and an operation position is created based on the teaching data.
An interpolation operation unit that creates an operation position at a speed multiplied by a speed ratio; an inverse conversion unit that converts the operation position into an operation position of each axis; and an operation command data created from the operation position of each axis, and a servo drive. An operation command data creation output unit that outputs operation command data to the system, and a correction value obtained by dividing the parameter of the designated speed of each axis joint by the command data that is commanded this time at the timing of outputting the operation command of each axis, for each axis A correction value calculation unit that calculates the minimum value of the calculated correction value for each axis, and multiplies the minimum value of the selected correction value by the speed ratio,
A control device for an industrial robot, comprising: a speed ratio calculation unit for setting a next speed ratio.