• aditya mehrotra.

some knowledge: why’d I keep messing up the IK in 3D? BASEFRAME CONCEPT [to knows]

So if you saw the last posts on 3D inverse kinematics I was really messing many things up none of the values we were getting were making sense until the end.

I think in 2.12 lecture today I found the concept I was missing. The concept is called BASEFRAME.


So the BASEFRAME is the base coordinate system of the robot. It occurs even BELOW the first actuator it’s the robots xyz home and axis directions. What I have been doing is assuming the first actuator is the home and when we rotate by theta the transforms get messed up. This is NOT the case, we need a BASEFRAME THAT IS NOT ACTUATED. And then after the first actuator you get the theta-1 rotation. And the first vector in the forward kinematics with NO rotation matrix in-front of it is the vector FROM THE BASEFRAME to the FRAME OF THE FIRST ACTUATOR. That’s what we have been messing up!


Note - I finally accounted for this in the LAST calculation of the previous CHIP IK post.


Coming soon is the jacobian stuff which is really interesting :)


#robotics #becarefulwithmath #omgrobots #inversekinematics #baseframe

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