How To Attach An End-Effector To Your Robot

Since there are little to no established standards for attachment interfaces in the robot industry, many things are to be considered by end-effector manufacturers, integrators and users for end-effector attachment design. This post first explains how to determine the forces and moments that your end-effector attachment must hold. Then, we present ways of attaching the end-effector to the robot. An Excel spreadsheet can also be downloaded to get you started in your calculations.

How to design the interface

Basic method: the static moment. Gripper End-Effector Moment Calculation Sheet

1. Find the center of gravity of the end-effector and the part: CG
2. Calculate the distance from the CG to the bottom of the tool plate: D
3. Determine the maximum weight of the EOAT and the part: W
4. Calculate the static moment
5. Select your interface so it can hold the the maximum static moment - note that the interface height adds to the distance D and increases the moment M

Advanced method: dynamic forces and moment analysis. Gripper End-Effector Moment Calculation Sheet

1. Determine the CG of the object and of the gripper
2. Determine the maximum weight of objects that will be grasped and of the gripper
3. Determine the maximum acceleration occurring during the process
4. Calculate the resultant force
5. Calculate the resultant moment
6. Select your interface so it can hold the the maximum static moment - note that the interface height adds to the distance D and increases the moment M

How to attach the interface
Now that you know the maximum payload and moment you can handle, you have to attach your end-effector to the robot. Keep in mind the height of the interface stacks to the centroid distance D. Increasing D does increase the resulting moment.

Using a faceplate: Related to the robot model, you will have various screw and dowel pin patterns.

• Screw the faceplate on the robot
• Insert the gripper, dowel pins provide orientation, precision and repeatability (each time you remove the gripper for tool changing or maintenance, the dowel pin ensures repeatability)
• Secure the gripper with the screws matching the interface, using Loctite will help

The above methods can also be used to determine the required specification for a robotic tool changer. On this topic, you can read the top 5 problems of robotic tool changers.