In some production and processing processes, the robot operates the workpiece instead of the tool. In this case, in order to successfully program, it is necessary to measure the external TCP of the fixed tool. This is the significance of this article. Only by mastering the measurement method of the external fixed tool can we better carry out future practical operations.
KUKA robot’s external fixed tools play a vital role in various applications. These tools are attached to the robot and remain stationary relative to the robot’s end – effector during operation.
They are designed to perform specific tasks precisely. For example, welding torches can be fixed externally to ensure stable and accurate welding. These tools enhance the robot’s functionality, allowing it to handle complex jobs more efficiently. They are essential for improving production quality and productivity in manufacturing processes.
1 Measurement principle
(1) Definition
External fixed tools refer to tools that are not installed on the robot flange and move with the robot, but are fixedly installed in the external space of the robot.
(2) Application areas Some production and processing processes require robots to operate workpieces instead of tools. The advantage is that the parts can be processed without being placed in advance, so clamping tools can be saved, such as bonding and welding. For successful programming of such applications, it is necessary to measure the external TCP of the fixed tool and measure the workpiece.
(3) Measurement principle
Although the tool is a fixed (non-moving) object, the tool still has a tool reference point in the coordinate system to which it belongs. This reference point is called the external TCP. Since this is a non-moving coordinate system, the data can be managed like the base coordinates and can be stored as base coordinates! The (moving) workpiece can be stored as tool coordinates. Thus, it is possible to move along the edge of the workpiece relative to the TCP. It should be noted that when moving manually with a fixed tool, the movement is relative to the external TCP! Therefore, the determination of the external fixed tool is divided into two steps: 1) Determine the position of the external TCP relative to the origin of the world coordinate system. To determine the position of the TCP point, the robot-guided measured tool tip needs to be moved to the external tool TCP. 2) Determine the attitude of this coordinate system based on the external TCP. To determine the attitude, the robot flange coordinate system needs to be calibrated parallel to the new coordinate system. There are two ways: 5D method: Only the working direction of the fixed tool is informed to the robot control system. The working direction is the default X axis, and the attitude of the other axes is determined by the system. That is, the coordinate system is adjusted to +X new coordinate system // -Z flange coordinate system 6D method: The directions of all 3 axes are informed to the robot control system.
The coordinate system will be adjusted to +X new coordinate system//-Z flange coordinate system
+Y new coordinate system//+Y flange coordinate system
+Z new coordinate system//+X flange coordinate system
2 Measurement operation steps
Step 1:
Menu path: Robot button>Start operation>Measurement>Fixed tool>Tool.
Step 2:
(1) Give the fixed tool a number① and name②, and confirm with the Continue button④. (2) At this time, the external tool is located at the robot foot③
Step 3:
Enter the tool coordinate number of the external tool reference, and confirm with the Continue button.
Step 4:
Select a variable at column 5D/6D②, and confirm with the Continue button③.
5D: +XBASE is aligned parallel to -ZFLANGE (that is, the connection flange is adjusted to be perpendicular to the working direction of the fixed tool)
Note: 5D tells the robot control system the working direction of the tool, which is the default X axis. The directions of other axes will be confirmed by the system and cannot be defined by the user. Application range: MIG/MAG welding, laser cutting or water jet cutting.
6D: The connection flange should be adjusted so that its axis is parallel to the axis of the fixed tool. +XBASE is aligned parallel to -ZFLANGE
+YBASE is parallel to +YFLANGE
+ZBASE is parallel to +XFLANGE
Step 5:
Move the TCP of the measured tool to the TCP of the fixed tool, press Measure, and determine the position of the external tool relative to the world coordinate system.
Step 6:
Align the coordinate system of the robot flange to the fixed tool coordinate system, that is, +X tool coordinate system ∥ -Z world coordinate system, +Y tool coordinate system ∥ +Y world coordinate system, +Z tool coordinate system ∥ +X world coordinate system.
Step 7:
Press “Measure” and click “Yes” to confirm the position.
Step 8:
Press “Save”.
3 The robot moves in the external coordinate system. The active workpiece coordinate system is a moving coordinate system. The data can be managed like the tool coordinate system and can be stored as the tool coordinate system; the fixed tool coordinate system is stored as the base coordinate. When manually moving in the external coordinate system, the movement is relative to the external TCP, and the actual movement direction is opposite to the direction of the coordinate system movement key.
Step 1:
Select the tool number of the active workpiece to be moved in “Tool Selection” (the active workpiece is stored in the tool coordinates) and select the fixed tool number in “Base Coordinate Selection”. Select “External Tool” for Ipo mode.
Step 2:
Select the tool coordinate system used by the movement key.
Step 3:
Set the manual magnification.
Step 4:
Press the confirmation key to the middle gear.
Step 5:
Use the movement key to move the robot. Note that all movements are relative to the TCP at this time, not the tool guided by the robot.