JPH04123403U - robot control device - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to perform accurate work without the need for complicated correction calculations in a robot control device that moves the robot body along an external axis and simultaneously controls the robot body in a coordinated manner. . [Structure] An absolute coordinate system with an arbitrary point on the movement axis as the origin is set as a stationary robot coordinate system, and correction is performed by performing coordinate transformation between this stationary robot coordinate system and the robot coordinate system on the robot body. Eliminates the need for calculations. Thereby, the working range of the robot body can be expanded along the movement axis.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a robot control device that has a coordinate transformation function including external axes. It is.

0002

[Conventional technology]

Conventional robot control devices include, for example, a robot main body with multiple joint axes. After the body is suspended from the moving axis and moved, the workpiece is held stationary by this robot body. There is a known device that causes a person to perform a predetermined task (see FIG. 1). In such a robot control device, the workpiece can be set on any orthogonal coordinate axes on the workpiece. Set the coordinate system, and change the position and orientation of the hand of the robot body in the workpiece coordinate system. It is taught as a standing position. When playing, first set it on the robot body as shown in Figure 3. The taught position in the workpiece coordinate system is coordinate-transformed into the robot coordinate system. After that, the position and orientation of the robot body in the coordinate-transformed robot coordinate system are The joint angles of each joint axis are converted to control each joint axis of the robot body.

0003

[Problem that the idea aims to solve]

If the workpiece is large compared to the operating range of the robot body, the robot control This allows the robot body to move along the movement axis while simultaneously moving the robot body. It is necessary to control the many joint axes of the workpiece to perform work on the workpiece. However, whereas the robot coordinate system moves as the robot body moves, , the workpiece coordinate system remains stationary. Therefore, when viewed from the moving robot coordinate system, the workpiece's apparent position is shifted. It will end up being put away.

0004 In such cases, in order to perform more accurate work on the workpiece than the robot itself, For this purpose, it is necessary to correct the apparent positional shift of the workpiece. For this reason, in the program that describes the robot motion, the coordinate correction calculation is performed at the teaching position. This work had to be done every time, but it was very complicated. In this way, since the robot coordinate system that moves along the movement axis is a relative coordinate system, Work on a stationary workpiece while moving the robot body along the travel axis. In this case, there was a problem that complicated correction calculations were required. In addition, for robot control In this case, axes other than the robot's joint axes, such as the travel axes, are called external axes. The present invention was made in view of the above-mentioned conventional technology, and the robot body, external axis This robot allows accurate work without the need for complicated correction calculations when coordinating control of The purpose of this invention is to provide a bot control device.

[0005]

[Means to solve the problem]

The proposed configuration achieves this goal by moving the robot body along an external axis. At the same time, the robot controls the robot body to perform a predetermined work on the workpiece. a stationary robot coordinate system whose origin is an arbitrary position of the external axis; is set as the absolute coordinate system, and the stationary robot of the work coordinate system on the robot body Find the movement vector in the coordinate system, and convert the movement vector into an absolute relative to the workpiece. Coordinates are converted to a moving vector in the stationary workpiece coordinate system set as the coordinate system, From the position and orientation of the robot body taught in advance in the stationary workpiece coordinate system, the stationary The robot body is determined by subtracting the movement vector in the stationary workpiece coordinate system. It is characterized by controlling.

[0006]

【Example】

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 1 shows an embodiment of the present invention. The robot control device shown in the figure moves a robot body 1 along an external axis 2 and at the same time controls the robot body 1 to perform a predetermined work on a workpiece 3. The robot main body 1 has a large number of joint axes θ ₁ , θ ₂ , θ ₃ , θ ₄ , θ ₅ , and θ ₆ and is capable of arbitrary movements in a three-dimensional space. The traveling axis 2 suspends the robot body 1 and moves it in the order of positions S ₁ , S ₂ , S ₃ , . . . S _n .

The robot control device of this embodiment has a coordinate transformation function including the movement axis 2, and cooperatively controls the robot body 1 and the movement axis 2 according to the following procedure. First, a stationary robot coordinate system is set with the pre-movement position _S1 on the movement axis 2 of the robot body 1 as the origin. The "stationary robot coordinate system" is an absolute coordinate system with the origin at position _S1 on the moving axis 2, and does not move even if the robot body 1 moves. Next, a stationary workpiece coordinate system is set based on the position and orientation of the workpiece 3 from the stationary robot coordinate system. The "stationary workpiece coordinate system" is an absolute coordinate system set from the stationary robot coordinate system, and does not move even if the robot body 1 moves along the movement axis 2.

On the other hand, a robot coordinate system is set on the robot body 1. The "robot coordinate system" is a relative coordinate system set on the robot body 1, and similarly moves as the robot body 1 moves. Therefore, if the unit vector in the moving direction of the moving axis 2 is V, the moving vector in the robot coordinate system is expressed as V(S _n -S ₁ ). Here, the movement vector V(S _n -S ₁ ) is a vector whose starting point is the origin S ₁ in the stationary robot coordinate system. During teaching, the position/posture P _n of the robot hand in the stationary workpiece coordinate system and the moving position S _n of the workpiece coordinates on the moving axis 2 are paired and taught as (P _n , S _n ). When there are multiple teaching points, the same process is performed for the multiple teaching points P ₁ , P _{2 .} . . P _n .

At the time of reproduction, as shown in FIG. 2, first, the movement vector V (S _n −S ₁ ) in the stationary robot coordinate system is coordinate-transformed into the movement vector ^W V in the stationary workpiece coordinate system. ^W T・^W V=V(S _n −S ₁ ) ^W V= ^W T ⁻¹・V (S _n −S ₁ ) However, ^W T: Transformation matrix from stationary workpiece coordinate system to stationary robot coordinate system Next , a vector ^W P _R from the moving position S _n of the work coordinate in the stationary work coordinate system to the position of the robot hand is determined. This is obtained by subtracting the movement vector ^WV in the stationary workpiece coordinate system from the position and orientation P _n of the robot hand in the stationary workpiece coordinate system. ^W P _R = P _n - ^W V ^W P _R = P _n - ^W T ^-1・V (S _n - S ₁ )

[0010] Thereafter, the vector ^W P _R obtained as described above is converted into a hand position ^S P _R in the stationary robot coordinate system. ^S P _R = ^W T・^W P _R ^S P _R = ^W T・{P _n − ^W T ⁻¹・V (S _n − S ₁ )} = ^W T・P _n −V (S _n − S ₁ ) The vector ^S P _R obtained in this way indicates the position and orientation of the robot hand in the stationary robot coordinate system, and since the stationary robot coordinate system is fixed in a space with absolute coordinates, the robot body 1 Even if the workpiece moves, the position indicated by _the vector ^SPR and the target position of the workpiece will not deviate. Furthermore, the vector ^S P _R in the stationary robot coordinate system obtained in this way is converted to a value ^W P _n in the robot coordinate system, and further, the value W P n in the robot coordinate system is converted to the value ^W P _n of each joint axis of the robot body 1. It is converted into a joint angle and given to each joint axis as a target value, while the movement position S _n is given to the movement axis 2 as a target value. Thereby, the robot main body 1 and the moving axis 2 can be cooperatively controlled to perform accurate work on the workpiece.

In this way, in this embodiment, a stationary robot coordinate system and a stationary workpiece coordinate system are set and coordinate transformation is performed between them, so the robot body 1 is moved along the movement axis 2 for teaching. Even in this case, the position indicated by _the vector ^SPR in the stationary work coordinate system and the target position of the work do not deviate. Therefore, the following effects are achieved. When the workpiece is large and the operating range of the robot body 1 alone is small, teaching and reproduction are possible by moving the moving axis 2. If the workpiece coordinate system is corrected for the positional deviation of the workpiece, the taught position can be regenerated, expanding the range of applications of the robot. Further, since the workpiece position shift can be corrected without requiring conversion of the teaching position within the robot operation program, the teaching time is shortened.

0012

[Effect of the idea]

As explained above in detail based on the examples, the present invention is based on a stationary robot seat. Since we have set up a reference system and a stationary workpiece coordinate system, and have made coordinate transformations between them, No complicated correction calculations are required when controlling the robot body and external axes simultaneously. Able to perform accurate work.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a robot control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing cooperative control between a robot body and a moving axis according to an embodiment of the present invention.

FIG. 3 is a flowchart showing control by a conventional robot control device.

[Explanation of symbols]

1 Robot body 2 Movement axes 3 Workpieces θ ₁ , θ ₂ , θ ₃ , θ ₄ , θ ₅ , θ ₆ Joint axes S ₁ , S ₂ , S ₃ ,...S _n Movement positions of the robot body P ₁ , P ₂ ... P _n teaching point

──────────────────────────────────────────────── ─── Continued from front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G05D 3/00 Q 9179-3H

Claims (1)

[Scope of utility model registration request] 1. A robot control device that moves a robot body along an external axis and simultaneously controls the robot body to perform a predetermined work on a workpiece, wherein the robot body is stationary with an arbitrary position of the external axis as the origin. The robot coordinate system is set as an absolute coordinate system, the movement vector of the workpiece coordinate system on the robot body in the stationary robot coordinate system is determined, and the movement vector is set as the absolute coordinate system for the workpiece in the stationary workpiece coordinate system. The robot body and the external axis are controlled by converting the coordinates into vectors and subtracting the movement vector in the stationary workpiece coordinate system from the position and orientation of the robot body taught in advance in the stationary workpiece coordinate system. Robot control device.