Wednesday, October 5, 2011

A tip for vision-guided robotics

It seems like everyone is doing vision guidance: using vision to guide a robot to pick up a randomly oriented part. Most often, the next step is then to insert the picked part into some kind of assembly or packaging, and this is where problems can start to emerge.

Often, when the robot gripper clamps or sucks down onto the part it will move slightly. This can cause problems if the next step is a precision insertion-type operation, so here’s a tip.

What you need is a registration step. Have the robot show the part to another camera. The computer can then use this image to calculate the positions of key features with respect to the gripper. These new coordinates can then guide the assembly step.

Now this isn’t my idea. I’ve seen several integrators do this kind of step, but one of the most interesting applications was covered in a case study from Xigent Automation Systems of Ohio. This is described in an Assembly Mag article, “Automation Profiles: Integrator Sheds Light on Assembly Challenge” published August 24th, 2011 but for better photos you need to look at the Robotic case study on Xigent’s website.

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