Questions
Working with Offsets
Hello Realvirtual.io Team,
in the robot configuration I deviate by -90 deg. on the Axis 2 and +90 deg. on Axis 3. Intuitively I tried to configure this with an offset, but as soon I try to calculate the inverse kinematics again and do path planning, things don't work as expected.
Range Axis2: -120; -5
When I add the offset of axis 2 by hand (lower limit: -30; upper limit: 85) then things work as expected, but since the robot will be connected via OPCUA Plugin, I don't know how to add the offset otherwise.
Robot: Kuka KR2700 prime
Thank you for your help!
Answer
So the axis positions are coming over OPCUA with a DriveFollowPosition? Easiest way is to position the axis in the OPCUA 0 Value position. But also Offset should work. Can you explain a little bit more your setup?
Hi, the "home" position (=position in Editor Mode) for our IK must be always this
Otherwise the IK will not work.
Ideally this would be also the OPCUA Positions where each drive has Position 0. If not you can work with Offsets in the Drives. But youh should only use Offsets for OPCUA and not for our included inverse kinematics.
Maybe it is best to define two robots. One using our IK with the correct settings and one getting the Axis values over OPCUA.
If you thing that our IK is doing something wrong (your last picture) - please send us your project where we can check this to: https://realvirtual.io/send
Please only include what we really need and set the scene to a situation where we can see directly your problem.
Yes, so we have the Kuka KR210 R2700 prime.
This is the position, where Axis 1 to 6 are all 0. Our Home Position is [0, 90, -90, 0, 0, 0]. Compared to your tutorials, examples this is a different start Position.This (https://www.kuka.com/-/media/kuka-downloads/imported/8350ff3ca11642998dbdc81dcc2ed44c/0000181027_de.pdf) is the technical data sheet, where I take the angles from.
I set all the axis based on the values provided in the technical datasheet. Next, I pulled over the joints from the model provided (the model is already configured after DH-Parameters).
After placing the CAD Coordinate Systems look a bit different, than the Axis Kosys (maybe one problem?).
We also tried configuring the robot in the configuration where we pretend the home position. Assuming the following image is [0,0,0,0,0,0]
Then it acutally mostly worked, but we had to write a second C# Script to add the offsets, since the position is actually [0,-90,90,0,0,0] but in the best case we want to add this via realvirtual.io and not a second piece of code.
Doing this setup, when sending the Angles to the robot, the robot actually drives to the correct position I ask for, when defining a target. But in the simulation it looks wrong.
Here in the picture above we can see, that the TCP of the endeffector points in the wrong direction (digital twin incorrect). The target kosys however is being reached by the robot in real live, when sending the angles via OPCua. So the inverse kinematics actually works correctly.
Thank your for your help. If this helps I could also send the unity scene. The realvirtual version I'm using is 2022.15.5212.
Customer support service by UserEcho
Hi, the "home" position (=position in Editor Mode) for our IK must be always this
Otherwise the IK will not work.
Ideally this would be also the OPCUA Positions where each drive has Position 0. If not you can work with Offsets in the Drives. But youh should only use Offsets for OPCUA and not for our included inverse kinematics.
Maybe it is best to define two robots. One using our IK with the correct settings and one getting the Axis values over OPCUA.
If you thing that our IK is doing something wrong (your last picture) - please send us your project where we can check this to: https://realvirtual.io/send
Please only include what we really need and set the scene to a situation where we can see directly your problem.