Moving a point along tool axis

    Hello every one!

    I have an arm that is using a camera to find a part. Theses parts are arranged in a 16x2 array. I started out with a point called XPick which is at the X0Y0Z0 of base[16]. I then offset it to the next part in the array and take a picture, Get the cameras offsets add them to XPick and move the gripper there. Half way down the long side of the array I need to A180 the camera to avoid crushing my end-of-arm tooling. The problem is the camera is now the opposite orientation of my base, so the X and Y offsets are wrong. Is there a way to move a point like Xpick in relation to the cameras frame?

    I assumed I needed the geometric op but my experiments with it were fruitless.

    I was going to post pictures and code but I'm not sure what would be helpful. Let me know if any one has Ideas or needs more info!

    The camera is mounted to the robot end effector, yes?

    It sounds like you are using a Tool-mounted camera to perform Base shifts. That's... odd. Doable, but odd.

    How did you do your original robot<>camera calibration? And how are you changing XPick's rotation?

    Generally, to use a Tool-mounted camera, you create a TCP that is aligned with the camera, and apply the camera corrections in that TCP.

    So, you would move to the photo-taking position using Base shifts, as normal. Then, when taking the camera shot and getting the correction data, apply that in Tool. So, something like:

    There's programatically better ways to do this, and much more robust. But that's the general idea.

    Quote from SkyeFire

    The camera is mounted to the robot end effector, yes?

    Yes, it is a tool mounted camera.

    Quote from SkyeFire

    It sounds like you are using a Tool-mounted camera to perform Base shifts. That's... odd. Doable, but odd.

    I never rotate or shift the base. I have a point (Xpick) that starts at the base and is constantly moving.

    Quote from SkyeFire

    How did you do your original robot<>camera calibration? And how are you changing XPick's rotation?

    For the original calibration we used a cad model of the end effector to get the numerical data.

    Quote from SkyeFire

    Generally, to use a Tool-mounted camera, you create a TCP that is aligned with the camera, and apply the camera corrections in that TCP.

    Lets say the camera sees the part is off {X 10, Y -55} you are saying I should adjust the gripper TCP instead of XPick?

    Quote from SkyeFire

    LIN $POS_ACT_MES : {CameraX, CameraY, 0, CameraRZ, 0, 0} ; apply camera shifts in Tool frame

    This bit of code was what I needed to know. Thank you skyefire:thumbs_up:. Since the TCP is at XPick when it takes the picture

    Code
    XPick = $POS_ACT_MES:{camX, camY, 0, camA, 0 ,0}
$TOOL = gripper
LIN XPick

    Moves XPick to the center of the part with my gripper. This works good for my application.

    just out of curiosity Is there a way to accomplish this without my TCP being at XPick?:thinking_face:

    Quote from pyrojaymez

    just out of curiosity Is there a way to accomplish this without my TCP being at XPick?:thinking_face:

    Of course- that would require general solution whose specific case you just solved.

    General solution would be something like:

    1. Create geometric transformation chain to calculate where Xpick is in Tool/Camera coordinate system. Call this XPickInCamBase.

    2. Apply offset in Tool/Camera coordinate system to XPickInCamBase.

    3. Apply reversed transformation chain from step 1 to coordinates you got in step 2. Get XPickWOffset.

    4. In case the camera is not completely parallel to your workbase, transfer only X and Y (and depending on your setup maybe A) values from XPickWOffset to XPick.

    5. Profit!

    Edit: However temped you are, do not try to implement all these steps with one line of code. It becomes frustrating to debug.

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