Robotics Tech Papers
Coordinate System Frames in Industrial Robots
by Nikhil Niphadkar, Controls Engineer at Patti Engineering
Patti Engineering Posted 07/07/2017
It’s easy to teach a robot if you know what frame to teach the points in. If not, it can be a nightmare! If you are having hard time teaching a robot point in space or you are spending more than a few minutes to teach the point, I have to tell you: you ain’t doing it right!
In order to define a location and orientation of any object in space, we need 6 parameters: the distances in X, Y, and Z directions and the rotations around the three axes. All of these distances and angles are measured from a reference point called the “origin”. Every time the object moves in the 3-D space, these distances and angles change.
There are 4 types of frames used in robot programming.
World frame is attached to the base of the robot. This is also referred to as Cartesian Co-ordinate Frame
Tool frame is attached to the end of arm of tooling.
User defined frames accommodate strange shaped work-pieces, like an inclined work surface. It becomes very easy to program points along these surfaces if we define one of the axes along this inclined surface. User frames allow you to align the x, y, z coordinate system about a fixture or workpiece that is translated and/or rotated with respect to the world frame of the robot.
Jog frames are not very commonly used but these are very similar to user frames.
User frames are designed to make programming easier. But if you are accustomed to programming in a different frame (like world frame) and aren’t aware of how user frame works, it’s not easier; it can be frustrating! However, by using the best frame for your application, you can save steps in programming and headaches later on.