Robot cell interface

Citation

(2001), "Robot cell interface", Industrial Robot, Vol. 28 No. 1. https://doi.org/10.1108/ir.2001.04928aaf.008

Robot cell interface

Robot cell interface

Keywords KUKA, Welding

KUKA Welding Systems of Detroit has found ways to save time and avoid complications in the production of machine tooling and robot cell systems that it supplies to the big three car manufacturers. KUKA has automated the fine tuning of its robots. For instance, it clones robot cells by transferring robot programs between two or more cells.

Robot cells, in interpreting instructions downloaded from production robot programs, are often off the mark in the real world. Any number of less than perfect elements (for example, a damaged robot, end of arm tooling, or robot base construction) can cause a robot cell to miss its intended co-ordinates. The typical solution is touching up, a time intensive process of training individual robot cells to hit correct points through the use of a "teach" pendant, a hand-held input device that enables direct control of the robot's movement.

Tom Anderson, engineering manager of KUKA, said:

The benefits of robot cell calibration on, say, a vehicle program with identical installations at several plants are twofold … Calibration reduces the time needed to program robot cells, both at the shop and at launch at each of the customer's facilities, while providing a consistency in the robot programmes transferred between the robot cells, despite their being located in different facilities. In the past we would touch up each individual robot cell using planar alignment. That process involved using the uncalibrated robot as a measuring device to find the location of the fixture and was further limited to a 2D plane; with that method you can't specify a 3D transformation, such as "this rotation around this axis".

KUKA is using the DynaCal robot cell calibration system from Dynalog Inc. of Bloomfield Hills, Michigan. As a robot cell moves in a series of prescribed positions, the DynaCal system records 40 linear measurements and determines the "signature" (that is, the unique geometric parameters) of the cell. The user can create a CAD/CAE simulation program off lines and download the data into the robot cell. The system's filter function uses the signature of the robot cell to modify the data automatically, adjusting virtual co-ordinates according to the as-built parameters of the robot cell with an accuracy of more than 0.5mm. A single program can be downloaded, filtered and instantly modified in an unlimited number of robot cells. The DynaCal system gives the operator the ability to restore robot programmes after a crash.