Extending the previous model, I've closed a rudimentary CESAR loop in simulink. Error signals with varying noise levels are combined to bring a "cavity" to lock.  

There are many things that are flat out arbitrary at this point, but it qualitatively works. The main components of this model are:

• The "Plant": A pendulum with f0 = 2Hz, Q = 10
• Some white force noise, low passed at 1Hz before input to the plant.
• The Controller: A very rough servo design that is stable...
• ALS signal: Infinite range Linear signal, with a bunch of noise
• Transmission and PDH signals are computed with some compiled C code containing analytic functions (which can be a total pain to get working), have less noise than ALS
• Some logic for computing linearized PDH and SqrtInv signals
• A C code block for doing the CESAR mixing, and feeding to the servo

And it can lock! 

Right now, all of the functions and noise levels are similar to the previous simulation, and therefore don't tell us anything about anything real...

However, at this point, I can tune the parameters and noise levels to make it more like our interferometer, and thus maybe actually useful.