LitePlacer.com forums

I have been looking through the code, and it doesn't look like you take into account the needle "wobble" in measuring the needle offset. For the wobble correction, it looks like you just figure the dx,dy from angle1->angle2 as it's being rotated but I don't see anywhere where it takes into consideration the initial offset values - which is why I think I'm getting some offset errors when I'm calibrating my needle.

I have simple solution for this that I can implement, but I just want to know if I'm missing something in the code. I think the additional step is to compute a true offset by subtracting the vector to the needle in the upcamera from the center of the viewport. You would need to then do a needle calibration and add whatever needle offset is for any given angle to determine where the offset between the camera and and needle are whenever you do a needle move operation.

When do a 'pickup here' I notice that it doesn't do a needle calibration beforehand, so I would assume that it doesn't compensate for needle wobble at all as it is currently configured.

Reza

The initial offset gets included when you set the up looking camera location.

In calibration, you place the needle to a point on a PCB, then look at the same point with the down-looking camera. This sets the needle - down camera offset. Then you take the needle to center of the up looking camera and set the up looking camera position. This is the reference location. If the needle would not wobble and needle tip would not change position when you change the needle, deviation form the nominal values would always be 0. But the tip moves, so the tip deviation is measured for several rotation values, including zero. In operation, the system needs to know the true offset between the down looking camera and needle tip, and this is the nominal offset + measured deviation. Ok?

If you get constant offset error, your initial calibration has been off.

> When do a 'pickup here' I notice that it doesn't do a needle calibration beforehand, so I would assume that it doesn't compensate for needle wobble at all as it is currently configured.

This is an error.