3.4.10

I talked to my advisor about my concern that I don't have any papers on deck now that my experiment is essentially in place. He didn't seem that worried, so I guess that's all that matters, and assured me that we'd get things going soon enough. He mentioned that the easiest, publishable experiment to work towards would be designing an LQR controller using an identified noise model. However, he's still stressing the idea of running the experiment in real time, so I'm going to have to either make some real advances there, or exhaust all the practical possibilities.

I've managed to get the Simulink version of the PI controller working about as fast as the M-file version. Nominally, sending commands to both actuators each iteration, I can run the thing around 4 Hz. Pretty pathetic, but there are a few things I can work on to speed things up.

WFS: the current sub aperture array size, around 30x45, encapsulates most of the actuator influence functions for the beam size I'm using right now. With partial frame mode, I can capture images of that size at around 45 fps. Since I'm no where near that, and reducing the beam size further would be a pain in the ass, this serves as an upper bound on performance for now. Still, with that many lenslets, computing the slope vector can only be done around 10 Hz. This number of sub apertures is much much higher than what others use, so one idea is to down sample the image and compute centroids for a set of lenslets, like every third or something. I think this would be a linear improvement in the performance of the slope vector calculation.

DMs: the mirrors clearly have some dynamics, so there has to be some pause between sending a command and reading the WFS. When computing a poke matrix, a pause of less than 0.08s yields crappy results, but the PI controller works pretty well when there is no pause at all.

Tomorrow I'd like to look at the down sampling idea since that shows the most promise. There's also the idea of doing the slope calculation in an M-file S-function instead of an EML block. I doubt that'd really improve things much, so its on the back burner for now.