Complex mechanics/dynamics problem

[Zizzac]

So this is the problem. Relevant equations should be:

Aa = Ab + Aa/b
Va = Vb + Va/b

and vector notation:

Aa = Ab + ω' x r + ω x (ω x r) + 2ω x Vrel + Arel

I have no attempt at this because I am currently working on it and really have no idea if I am going in the right direction.

Can anybody help?

Homework Statement

Homework Equations

The Attempt at a Solution

 

[OldEngr63]

Is the distance r1 variable? I presume that the distance r is considered as a driving motion, but how does changing r cause anything else to change? It looks like r could change without requiring motion anywhere else. Something is quite unclear about this mechanism.

Where are a and b? (the lower case letter points)?