benaiahhenry
Lifetime Supporting Member
Hi Everyone,
I've got what is (at least to me, since I've never done it before) and interesting AB motion control task that I'm looking into. I've attached a PDF with a mockup of the system so that hopefully my description of the machine and what it needs to do will be clearer.
The basic idea is that I am using a camera to inspect the top few mm of the top of the side of a part. The part is spun on a Theta axis, which is mounted on a X, Y table. A camera is mounted looking at the top of the part. The camera needs to be kept fairly normal to the part, and I am given a lookup table for X and Y relative to the Theta angles, so I can just set up a CAM for X and Y to Theta.
Where it starts to get complicated is that these parts are not symmetric and there is a lot of size variation even among good parts. So the Camera is also mounted on a stage (X`) that moves in and out relative to the top of the part. I also have a laser distance sensor that measures the distance from the camera to the top of the part. The part I am trying to figure out is how to best control the position of the camera stage based on that analog signal from the distance sensor.
I have a 4 mm depth of field that I am trying to keep my camera in and obviously the motion needs to be fairly smooth.
This will be a ControlLogix L72 project, but other than that hardware is still fairly open to spec.
On some controllers I've seen it done where you can actually close the servo loop on an Analog input. Is this possible with an AB controller? I've not been able to find anything about that in any of the Drive User Manuals.
This is another approach I found in the KB, using swapping MAM instructions: https://rockwellautomation.custhelp.com/app/answers/detail/a_id/23100
I do have enough information to be able to set up the "ideal" cam for the camera axis, but even if I do that I still need some way to modify it on the fly since that parts are not ideal.
I'd love to hear how any of you have done something like this in the past.
Thanks!
-Benaiah
I've got what is (at least to me, since I've never done it before) and interesting AB motion control task that I'm looking into. I've attached a PDF with a mockup of the system so that hopefully my description of the machine and what it needs to do will be clearer.
The basic idea is that I am using a camera to inspect the top few mm of the top of the side of a part. The part is spun on a Theta axis, which is mounted on a X, Y table. A camera is mounted looking at the top of the part. The camera needs to be kept fairly normal to the part, and I am given a lookup table for X and Y relative to the Theta angles, so I can just set up a CAM for X and Y to Theta.
Where it starts to get complicated is that these parts are not symmetric and there is a lot of size variation even among good parts. So the Camera is also mounted on a stage (X`) that moves in and out relative to the top of the part. I also have a laser distance sensor that measures the distance from the camera to the top of the part. The part I am trying to figure out is how to best control the position of the camera stage based on that analog signal from the distance sensor.
I have a 4 mm depth of field that I am trying to keep my camera in and obviously the motion needs to be fairly smooth.
This will be a ControlLogix L72 project, but other than that hardware is still fairly open to spec.
On some controllers I've seen it done where you can actually close the servo loop on an Analog input. Is this possible with an AB controller? I've not been able to find anything about that in any of the Drive User Manuals.
This is another approach I found in the KB, using swapping MAM instructions: https://rockwellautomation.custhelp.com/app/answers/detail/a_id/23100
I do have enough information to be able to set up the "ideal" cam for the camera axis, but even if I do that I still need some way to modify it on the fly since that parts are not ideal.
I'd love to hear how any of you have done something like this in the past.
Thanks!
-Benaiah
