Need help untangling a block diagram
Hello everyone, I need some help figuring out how to untangle this block diagram to find the transfer function.
Usually I do these types of exercises easily, but in this one I'm really confused by the two vertical H4 blocks that go into the same summing junction.
I just need a hint for the first step. I suspect I need to focus on the inner part of the diagram first (on the H4s), to remove that summing junction and unlock the H3 feedback loop and then it should be a piece of cake from here on out.
I've tried reasoning about the signals going into the H4s, something like that U1*H4+U2*H4 = (U1+U2)*H4. I drew it out, but it doesn't make sense to me and I think it's the wrong approach.
Any tips on the algebra or block moves needed to handle that central node? Thanks!