I'm Doing Science!

Turns out expecting to produce a poke matrix by last Friday was a tad optimistic. After all, why should I expect my $15000 mirror to work out of the box or come with directions? What am I, some naive undergrad researcher?!

Most of of the problems stemmed from the example code I was sent, which contained several errors based on the "version" of the software I was using. Some of those I fixed myself, which I guess is good in retrospect since it forced me to get to know a few of the intimate joys of .NET. I'm sure this will be useful when some piece of code decides to shit the bed later.

In any case, I finally have some code written that I can use to command the USB, 31 actuator mirror using this new interface. Putting me functionally in the same place I was months ago. For some reason I still can't see the new DM from either the bundled software of Matlab, so that will take some further tinkering and emailing. It would be optimistic to plan on having this fixed by next week.

Nonetheless, tomorrow the plan is to get use to this new code and verify its producing the same results as before. Since we have 2 of the new 61 actuator DMs, I should be able to swap the hardware around to pinpoint the problem. I suspect its just some stupid software parameter somewhere that has to be checked, but its probably going to take an email to the manufacturer to figure out.

Sugar Momma

Like every good grad student I'm always looking for ways to get more money. One way of approaching that is to look at the current buzzwords that are flying out of research journals, and finding ways to use your own research in those areas.

Networked control systems seem to be a popular research topic in the control engineering world these days, and one of the major headaches there seems to be the uncertain time delay that results from unreliable data networks. I haven't read enough to know how this is dealt with in practice, but I would guess some kind of ZOH handwaving is used to duct tape the problem.

The AO problem deals with time delays explicitly by predicting future outputs. This is possible since wavefronts exhibit some correlation so we can usually do better than pure guessing on average. Adaptive controllers work even better because the nature of the correlation is uncertain or changes over time.

NCS problems also have time delays, but the problem is exacerbated because the delay itself is unknown. On the other hand, would it be outrageous to assume that the delays might be correlated? If that's true, could you design an adaptive controller/observer that provided an estimate that performed better than ZOH?

In other words, could you consider random delays as simply changes to the PSD of the measured signal? If so, then an adaptive controller might have some promise.

Hmm, this could all be nonsense on second thought.

Vacay's Over

Its been a relaxing month of unmitigated laziness since I passed my Quals. In that time I've managed to do less than I ever thought possible, other than ski and eat.

The presentation itself, rushed into production like a Soviet washing machine, went over well. Taking a hint from all the seminars I've slept through, I tried to avoid putting in too much text that would be ignored and instead focused on graphics and charts that I could explain. In my experience, this approach is what usually separated a presentation given by a grizzled transparency veteran, new to powerpoint but not to verbose explanation, and a recently minted academic who still possessed the new PhD smell.

Scheduling it during finals week turned out to be a blessing. Since most of my committee had limited time to spare between giving exams and review sessions to the little ones, I only had an hour or so to talk. A mere 40 minutes remained by the time everyone arrived and I finally opened my mouth, but this limit meant that I could avoid any really technical questions.

Anyway, with a supposedly clear path ahead, the next step is to install and test out the new 61 actuator DM we received. I actually came in a few days over the break to do some alignment, despite the department's attempt to prevent this by turning off the lights and stopping garbage collection. This week the focus will be on commanding the mirror itself. This new mirror only has twice the actuators, but apparently sending it commands is ten times as difficult. Rather than a simple USB driver box, signals to this mirror travel through an NI DAQ card before hitting some other voltage amplifier that actually connects to the actuators. To use this system with Matlab I'll have to upgrade to 2009A, and use the .NET interface to access the DM driver's DLL library. Hooray.

A rough, optimistic schedule of events:

Tues: Finish installing cables, test mirror functionality using V. 1.8 software, begin dissecting AOS .NET example code

Wed: Upgrade Matlab if possible, continue code dissection

Thurs: Adapt code into Matlab DM control function

Fri: create 61 actuator poke matrix