Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Live Measure and Correct Implementation


I'm looking at performing live path corrections to better improve the accuracy of a robot in real time.

We would like the robot to perform machining, utilizing a laser tracker or similar vision based TCP state estimation system in attempt to compensate for deflection, etc.
Ultimately the goal is to also have the system recognize deflection and adjust in attempt to combat chatter.

From what I've gathered,
We can use the delta values, between where the robot thinks it is and it's observed position, to adjust the reference frame of move commands before they are called, however once a path is in motion it won't update if the reference frame moves.

I remember seeing an example where a robot was machining a long asymmetric, tiered, circular object rotating on a secondary machine, (sort of like automated lathing).
This gives me hope that such can be done, hopefully without too much difficulty.

Any advice?
We have been involved in projects where we would compensate accuracy for static points (move-measure-correct). The robot moves to a nominal position, the laser tracker or measurement system measures, we calculate a delta error (in 3D -position- or 6D -position and orientation) and we move the robot to compensate the errors. This can be done iteratively, and after 2 or 3 iterations you should be within 0.1 mm position accuracy. This is possible with the RoboDK API in a robot agnostic manner and we have a few examples we can provide.

On the other hand, it is a bit more challenging if you want to compensate the robot movement/path in real time. This would highly depend on the robot controller. Not all robots support this feature. For exmple, on a Fanuc robot controller you would need an option called DPM (Dynamic Path Modification). This allows you to update a register an offset to compensate the nominal error.

It may be better if you can provide more details about your application. We can definitely help you in the first scenario.
While I was originally planning to focus on developing and evaluating a high accuracy move-measure-correct 6DOF system, using Charuco board(s) as an alternative to manual frame teaching.

Supervisors are continuing to expect Dynamic Path Modification.

We have a Staubli TX200 with CS8C HP Controller, running ValHSM to operate the spindle.

P.S. I found some info on the forums on what ports to try when attempting to connect through RoboDK, is that information available somewhere we can reliably access instead of exploring through the forums? (for any robot like Staubli/Doosan/UR etc)

Users browsing this thread:
1 Guest(s)