This procedure covers setting up collision groups and interference groups in a cell containing multiple robots that will work simultaneously.
Cell layout
For this procedure, a basic simultaneous two-robot cell is used, with both robots at the same side of a work table.
Cell dimensions for this example:
Spacing between robots (at base): 1500 mm
Spacing between robots and table: 1600 mm
Table height: 500 mm
Each robot contains safety envelopes around J3 and J4, wrap style with a 100 mm extension.
The collision groups for this cell will be set up to:
Check for physical collisions between robots, cells, and workpieces.
Check for interferences or near-miss situations using safety envelopes.
Robot-to-part collision groups
Robot-to-part collision groups for multiple robots can be created with one group for each robot. This will make it possible to view and manipulate collision groups for each robot independently in a part programming session.
Create robot-to-part collision groups for each robot
With a device open in a Cell editor session, open Cell settings.
Select the [+] button next to Collision group pairs to add a new collision group.
Click the Edit button for the group.
Enter a descriptive name, such as “Left Robot to Part”.
Keep Type set to Collision and Color set to red.
In the Available Geometries section, expand the Cell node and the first robot node (“ROBOT_1_LEFT” in the image). Objects in first robot are listed below it.
Add Joint2, Joint3, Joint4, Joint5, and Joint6 to the Pairs section, in the box on the left. Include any other joint or link geometry for these joints, but do not add any safety envelopes (for example “J4_Wrap”) to the box.
Expand the Toolings node, then drag the first robot’s tooling to the Pairs section, in the box on the left.
From the Available Geometries section, drag Workpieces, Fixtures, and Stocks to the Pairs section, in the box on the right.
Click OK.
With the collision group set up in this way, the first robot and the tooling mounted on it will be checked for collisions against workpieces, fixtures, and stocks. If any of the objects in the left box touch any of the objects in the right box, a collision will be detected.
Repeat steps 1 - 10, but this time for the second robot.
Once this is completed, you will have two collision groups, one group per robot, which will check for collisions between a given robot and parts.
Robot-to-cell collision groups
Robot-to-cell collision groups for multiple robots can also be created with one group for each robot. This will make it possible to view and manipulate collision groups for each robot independently in a part programming session.
Create robot-to-cell collision groups for each robot
Open Cell settings.
Select the [+] button next to Collision group pairs to add a new collision group.
Click the Edit button for the group.
Enter a descriptive name, such as “Left Robot to Cell”.
Keep Type set to Collision and Color set to red.
In the Available Geometries section, expand the Cell node and the first robot node.
Add Joint2, Joint3, Joint4, Joint5, and Joint6 to the Pairs section, in the box on the left. Include any other joint or link geometry for these joints. Normally, you would not add J1 or Base, as these may already touch other cell components like a floor. Also, do not add any safety envelopes (for example “J4_Wrap”) to the box.
Expand the Toolings node, then drag the first robot’s Tooling to the Pairs section, in the box on the left.
Expand the Tools mode, then drag the first robot’s Tools to the Pairs section, in the box on the left.
From the Available Geometries section, in the Cell node, drag cell components into the Pairs box on the right. In this example, Table is the only cell component that will be used for collision checking.
Click OK.
With the collision group set up in this way, the first robot, tooling, and tools will be checked for collisions against the table. If any of the objects in the left box touches the table, a collision will be detected.
Repeat steps 1 - 10 for the second robot.
Once this is completed, you will have two collision groups. Each group will check for collisions between a robot and cell components.
Robot-to-self collision groups
Robot-to-self collision groups for multiple robots should be created with one group for each robot. This group type checks that the toolings and tools of a given robot do not collide with its joints.
Create robot-to-self collision groups for each robot
Open Cell settings.
Select the [+] button next to Collision group pairs to add a new collision group.
Click the Edit button for the group.
Enter a descriptive name, such as “Left Robot to Self”.
Keep Type set to Collision and Color set to red.
In the Available Geometries section, expand the Cell node and the first robot node.
Add Base, Joint1, Joint2, Joint3, Joint4, and Joint5 to the Pairs section, in the box on the left. Do not add Joint6, because it normally touches the tooling. Include any other joint or link geometry for J1 – J5, but do not add any safety envelopes (for example “J4_Wrap”) to the box.
Expand the Toolings node, then drag the first robot’s Tooling to the Pairs section, in the box on the right.
Expand the Tools mode, then drag the first robot’s Tools to the Pairs section, in the box on the right.
Click OK.
With the collision group set up in this way, the first robot’s base, joints, and links will be checked for collisions against its tooling and tools. If any of the objects in the right box touches the robot, a collision will be detected.
Repeat steps 1 - 10 for the second robot.
Once this is completed, you will have a collision group for each robot that checks for collisions with itself.
Robot-to-robot collision groups
For simultaneous multi-robot cells, robot-to-robot collision groups check for physical collisions between the robots.
In this example, there is one collision group which checks that the first robot’s joints, links, toolings, and tools do not collide with the second robot’s joints, links, toolings, and tools.
Using the steps in the previous sections, create a dedicated collision group for a robot-to-robot collision. In this example, there is a collision group called “Left Robot to Right Robot”.
When you are configuring the Pairs section, in the box on the left, add everything in the first robot that you want to check against for collisions with the other robot:
All of the first robot’s cell geometry (excluding safety envelopes).
The first robot’s Tooling.
The first robot’s Tools.
Next, in the box on the right, do the same thing for the second robot:
All of the second robot’s cell geometry (excluding safety envelopes).
The second robot’s Toolings,
The second robot’s Tools.
Once completed, the robot-to-robot collision pair should look something like this:
Interference groups and safety envelopes
For simultaneous multi-robot cells, safety envelopes can be used with interference collision types to alert you in situations where robots come close to one another and other cell components.
In this example, J3 and J4 of the robots have safety envelopes which will be used for this collision group.
Create a robot-to-robot interference group
Open Cell settings.
Select the [+] button next to Collision group pairs to add a new collision group.
Click the Edit button for the group.
Enter a descriptive name, such as “Left Robot to Right Robot Interference”.
Set Type to Interference.
Select a different color for the group. In this example, the Color will be set to yellow (A255, R255, G255, B0).
In the Available Geometries section, expand the Cell node and the first robot node.
Add the safety envelopes for the first robot to the Pairs section, in the box on the left. In this example, safety envelopes J3_Wrap_100 and J4_Wrap_100 for ROBOT_1_LEFT are added.
Add the safety envelopes for the second robot to the Pairs section, in the box on the right. In this example, safety envelopes J3_Wrap_100 and J4_Wrap_100 for ROBOT_2_RIGHT are added.
Click OK.
Create a robots-to-cell interference group
In Cell settings, select the [+] button next to Collision group pairs to add a new collision group.
Click the Edit button for the group.
Enter a descriptive name, such as “Both Robots to Cell Interference”.
Set Type to Interference.
Select a different color for In this example, the Color will be set to yellow (A 255, R 255, G 255, B 0).
In the Available Geometries section, expand the Cell node and the first robot node.
Add the safety envelopes for the first robot to the Pairs section, in the box on the left. In this example, safety envelopes J3_Wrap_100 and J4_Wrap_100 for ROBOT_1_LEFT are added.
Add the safety envelopes for the second robot to the Pairs section, in the box on the left. In this example, safety envelopes J3_Wrap_100 and J4_Wrap_100 for ROBOT_2_RIGHT are added.
Add cell components (such as Tables and Fences), Workpieces, Fixtures, and Stocks to Pairs section, in the box on the right.
Click OK.
In this interference group, if the safety envelopes from either robot come into contact with the table, workpieces, fixtures, or stocks, interference will occur. This can help give the robot programmer an indication when robots come close to these objects.