Hi, For my final university project, I’m trying to pick items based on specific qualities (like color) using an external camera from OnRobot and a Universal Robot E-series (UR5e). After the camera detects the item, the robot cannot move to the picking position provided by URCaps. The error message is: “The robot cannot reach the requested pose. Script function movej is unable to find an inverse kinematics solution.”
I would appreciate any help with this problem. Thanks.
The first thing to check are the values returned by the camera. Is this a valid, reachable pose?
Thanks for your answer, could you please help with how I can understand if the provided position is reachable for the robot?
Also, I changed some parameters in the camera task (the pick offset and approach offset), as a result the robot is moving but in wrong direction. I changed the calibration direction, the camera’s position and also the robot’s position but still the provided position by the camera is the same. I would appreciate if you could also help with this issue. Thank you so much.
I don’t have experience with the OnRobot camera but a common error with “unreachable pose” is the wrong direction (+/- 180°) of the z axis.
If the robot is moving now it should be something else, maybe the calibration. You should check this, manually moving the robot and compare the position, in reference frame, to the one in vision.
The camera always return the same position, regardless of the object position? How are the values returned, a waypoint?
We have several systems doing this with Balluff cameras. They don’t use a URCap - they just give us xy coordinates.
Each time we’ve set up a new system, we’ve had to figure out which way the camera thinks is positive and negative for each axis, and adjust accordingly (multiply by -1) in our scripts which process that position and feed it to the robot.
I have no idea if the URCap for the Onrobot camera gives any options for making changes - would think that would be built into their calibration process somehow.
I have seen this error many times when the robot is close to a singularity. When you are taking a picture, ensure that the robot is not close to a singularity (for example, ensure that the size of the determinant of the body Jacobian is not close to zero 5.3. Singularities – Modern Robotics, or more simply make sure the arm can bend at least 5 degrees with every joint when the photo is being taken.) Another way to combat this problem is to define way-points for your arm to follow en route to its final destination pose, sometimes the inverse kinematics program does better with shorter movements.
No, it change by changing the object position, It is somehow the same regrading to changing the calibration & camera’s direction.
yes, it return values of the position (x,y,z, Rx, Ry, Rz)
Thanks for your help, I couldn’t find how I can make this adjustment, yet but I’ll check it again. Thanks
Thank you for sharing your experience.