I'm revisiting the Wally kinematics, and somehow they're no longer making sense to me. If you refer to the Python code and the inverse kinematics PNG file Nicholas posted, I no longer understand how the equations for the "elbow angle" (angles C and D on the drawing) are calculated.

Looking at this now, it seems like the elbow angle should vary between 0 and Pi, but the equations generating this angle with the acos function will only generate values between 0 and Pi/2. Also, the value fed to acos seems to be attempting to calculate a length using a^2 + b^2 = c^2, but there's no square root function.

So am I loosing my math skilz, or does this really not make sense?

I've switched my inverse kinematics to calculating the small angle using acos(leg length / 2x arm length) and then calculating C & D using C = Pi - (2 * small angle), which seems to generate OK results, but I can't test for sure since I've got some other issues going on with the control software (related to not having forward kinematics available).

I've also made some progress on the forward kinematics, but I don't have anything actually working just yet. Holler if you're interested in helping and I'll post what I've got so far.