A brief discussion on two methods of measuring base coordinates of KUKA robots

Base

The base coordinate system is a Cartesian coordinate system used to describe the position of the workpiece. It is based on the world coordinate system.

In the default configuration, the base coordinate system is identical to the world coordinate system. It is up to the user to move it into the workpiece.

$BASE

BASE coordinate system in pre-run

The variables of the structure type FRAME define the setpoint position of the workpiece relative to the WORLD coordinate system.

X , Y , Z : Origin offset along the axis [mm]

A , B , C : Rotational offset of the axis angle [°]

Measurement benchmark

During the reference measurement, the user assigns a Cartesian coordinate system (BASE coordinate system) to the work surface or workpiece. The origin of the BASE coordinate system is a point specified by the user.

Advantages of Benchmark Measurements:

The TCP can be run manually along the edge of a work surface or workpiece.

These points can be taught with reference to the base coordinates. If the base coordinates have to be moved, e.g. because the work surface has been moved, the points are also moved with them, but do not have to be re-taught.

How many BASE coordinate systems can be saved depends on the configuration in WorkVisual. Default: 32 BASE coordinate systems. Variable: BASE_DATA[1 … 32].

There are 2 ways to measure base coordinates:

3-point method

Indirect method

Determine the base coordinate system. 3-point method

Move to the origin and 2 other points of the new base coordinate system. These 3 points define the new base system.

1. Select the number of a tool that has already been measured. Confirm with the Continue key.

2. Use the TCP to navigate to the origin of the new base. Click Measure. Confirm the safety query with Yes.

3. Move the TCP to a point on the positive X axis of the new base. Click Measure. Confirm the safety query with Yes.

4. Use the TCP to approach a point with a positive Y value in the XY plane. Click Measure. Confirm the safety query with Yes.

5. If required, you can have the coordinates and orientation of the measuring point displayed in increments and degrees (referenced to the flange coordinate system). To do this, press the measuring point. Then use Back to return to the previous view.

6. Click Save.

Determination of base coordinate system. Indirect method

When it is not possible to move in the reference origin, for example because it is inside the workpiece or outside the working space, indirect methods must be used.

At this time, the robot must move to 4 points of the reference, whose coordinates must be known. The robot will calculate the reference based on these points.

1. Select the number of a tool that has already been measured. Confirm with the Continue key.

2. Enter the coordinates of a known point in the new base coordinate system and move to that point with the TCP. Click Measure. Confirm the safety query with Yes.

3. Repeat step 4 three times.

4. If required, you can have the coordinates and orientation of the measuring point displayed in increments and degrees (referenced to the flange coordinate system). To do this, press the measuring point. Then use Back to return to the previous view.

5. Click Save.

Enter the reference values: The following values ​​are known, for example from CAD: The distance between the origin of the base and the origin of the world coordinate system The rotation of the base coordinate axis relative to the world coordinate system T1.

1. In the main menu, select Start-up > Measurement > Base coordinates > Numeric input.

2. Select a number and give a name to the base coordinate system to be determined. Confirm with the Continue key.

3. Enter the data. Confirm with the Continue key.

4. Click Save.

application:

$BASE=$pos_act uses the current coordinate value as the BASE coordinate system.

$BASE=BASE_DATA[1] uses the coordinate value of BASE_DATE[1] as the current BASE coordinate value.

Editor: Huang Fei