punt punt punt

punt punt punt

a few days ago on the facelolz i said that

It’s now conclusive that I do not ask enough questions when I get stuck on things, and that this is unacceptable as it will impact my work performance. (I theorize that this ask-questions problem is why I am so mediocre at school).
Therefore, my goal for the next two weeks is to ask at least five dumb but coherent questions a day, and as proof of that I will write the answers up on my blog.
(I am still thinking a bit as to whether this casual-question-asking will actually translate to me asking more questions when I feel like people expect me to know more than I actually do).

So! then i asked questions. turns out most of the questions were so silly they don’t even merit writing down and/or I’ve completely forgotten them. But here today I’m writing down some notes on controls courtesy of Shane with mock-quadcopter demos by Charles (not duplicated here).

some of those questions were silly questions like how do i do controls in real life, as opposed to in labview on a $10,000 national instruments card.
then my brain went “speaking of things i want[ed] to do consistently to improve on skills…”

src files. wacome graphire4 4×6, inkscape, gimp. crashlanding, caeldera, digitalstrip2 fonts from blambot. ~4.

all posts | all images ||  NEXT

the theory behind both is the same, ignore current incompetence (flaunt it? sorry, internet, for adding to the general scuz of atrocious material) and focus on learning learning learning to get to where i want to go…
(credit to MITERS folks for creative inspiration, including conversations with Dane about post-apocalypticc robot boxcar somethings.).

hmm. Right. controls.
Say I have a quadrotor. How would I go around implementing controls for it?
e.g. in 2.737 mechatronics class, we use a digital signal analyzer to characterize the plant. But no one tries to do that to their quadrotor. One possible way: mount quadrotor on stick, rotate it along one axis at a time. But, in real life:
Generally PD controllers.
If you didn’t know that, you could model it as a mass and damper (really simple model). Small number for damping (only comes from moving through air, minimal), e.g. damping coefficient of 0.1. Don’t know distribution of mass along quadrotor axis, so just model as evenly distributed — really does not matter since will end up tuning gains empirically anyway.
Proportional controller is like a torsional spring. Bigger error, bigger control effort.
Derivative controller is like additional damping. Otherwise, with proportional controller will correct for error but then due to lack of damping will oscillate.
Start out with too little gain, because then it will fly but drift off to the side. With too much gain, it will oscillate and flip over. Then slowly increase P gain.
Converging on the gains — a common method is Zieger-nichols. General idea is to up the P gain until it just begins to oscillate. Now up the damping (D gain) until compensate for oscillation, use some magical constants, … that sort of thing.
PD fine for flying indoors. But outdoors, wind will cause constant offset. Need I[ntegral] term. Also helpful if one motor is weaker than others, other sources of constant error.
Bandwidth and sampling frequency.
Limitation: how fast can control code loop run on microcontroller (mcu). Mcu has system clock (16Mhz for atmega’s). Rule of thumb, +-* each operation 1 clock cycle. Dividing integers four clock cycles. Floating point, tens of cycles. More margin because processor will need to respond to interrupts. This is upper bound on sampling frequency.
Lower bound, well, only need to respond to user input, and human reaction time perhaps 0.5 secs, 20 Hz. But also want to reject higher frequency noise e.g. from wind.
If calculate these and not overlap, need more efficient code or more powerful processor.
Tuning gains — actually pilot dependent. Some people like higher gain despite closer to instability because will respond quicker to sudden turns. While people shooting video will want higher damping so that footage is smooth, okay to more slowly respond to errors in position. 
Segging things are like quadrotors but with one axis instead of two.

misc. ubuntu things

I was always a bit disappointed that bash history saves  to disk only the session that is closed last.
Turns out there is a way to fix that:

vi ~/.bashrc
export PROMPT_COMMAND='history -a; history -r'


I have a vmware ubuntu 11.04 (natty narwhal) setup.
things I investigated today:

  • screenlets and digitalclock (“dark clean” theme)
    • digitalclock appears glitchy — artifact of vmware?
    • themes for the cairo-clock
      • http://gnome-look.org/index.php?xsortmode=high&page=0&xcontentmode=1861
        • http://gnome-look.org/content/show.php/Japanese+Theme+Cairo-clock?content=91147
  • equinox set of themes
  • elegant-gnome theme (was not able to get this to install) http://gnome-look.org/content/show.php/Elegant+Gnome+Pack?content=127826
  • wallpaper-clocks http://www.vladstudio.com/wallpaperclocks/browse.php
    • http://www.vladstudio.com/wallpaperclock/?northern_lights
    • http://www.vladstudio.com/wallpaperclock/?robots_in_love
  • orta theme http://mygeekopinions.blogspot.com/2011/06/how-to-install-orta-theme-pack-in.html

Currently settled at Dusk with transparent menubars

what is a “competent engineer”? (possibly this is just part 1)

mumble academic success mumble

Thinking back, I can’t remember accurately how I felt freshman year. Now if I’d written things down in a blog post… So here I go, reporting on how I feel now as a senior.

Lately, it seems like my conversations with people outside of bland filler (well, actually useful filler like knowing what is going on in my friends’ lives, but I qualify filler as things not really interesting to people in general) is focused on theorizing about how people learn.

I feel like I’ve been lost the entirety of my time at MIT. About all I can say for myself is that I can graduate and I am competent enough to… to? I honestly don’t know.

I’ve always been trying to find that missing something that would let me have a happy pset / general academic experience. When I say that I don’t learn well in the traditional academic model, I’m resigned, not “too cool for school”. Maybe if I were more confident in seeking help. Maybe if I trusted that if I asked my friends questions, they would make the correct judgment call for themselves about their level of hosage versus their obligation to me. Maybe if I studied the material better so that I could ask credible questions (instead of my general “?___? what is everything” that I know can’t be answered effectively) at office hours. Maybe if I didn’t care if I should have tried harder, should have read the textbook, should have attended lecture, should have not taken a class without the prereqs, and spoke up in office hours anyway.

But maybe all I needed to do all along was be optimistic enough to bug people to help me. Maybe I wasn’t missing anything except believing, trying, not flailing around and simply thinking things are doable.

I don’t know. I had a pretty wonderful psetting experience recently. And thinking back, I can’t remember a single instance where I had an experience like this. Even given my terrible memory, it can’t have been more than a handful of times. I’d given up. I’d concluded that the only thing to do is muddle along and build things and try to figure out — if I could do it over again, what I would try to do to get the most out of my classes. What if it wasn’t that I was incapable of learning from school, but rather that I just never figured things out? That would mean that to help other people like me, the key isn’t to make cool things to build, but rather to figure out how to learn the most from lectures and not flail around and get lost and lose self-confidence in the meanwhile.

So much for being secure in my goal to remain excited about everything and defiant about not digging deeper into a subject.

Lately an MIT admissions blog post title Meltdown has been making the rounds. It’s really popular because it strikes a cord in most / many students here, but not everyone. Is it better or worse to experience extremes of emotion? As usual, I suppose there is no single optimal Kp for the relationship between amount of stress and drama / emotional response in a person — but I can still wonder if there would be a more optimal one for me. How do I become competent? Yet even the competent people I know feel inadequate to some extent. So what hope is there?

I know, I know. I’m focusing on negatives again.

Maybe I can try that as an experiment — not care what people might think, just care about what makes me happy. For just a few weeks, not care about the fact that I’m never on time either to meetings or with homework, take that as okay. This is something I am working on. I am just a person with flaws, which is okay. (At least I haven’t killed anyone). YAY more experiments! 😀

I think other people would find this weird. But it makes me feel better, so what the heck. I’ll be that weird person with the weirdly personal blog. Because it’s my blog.
edit 11/1/12 AHHHH i am such a terrible group person person.  i… i’ll leave this up here because i think everyone else deserves a reminder that you’re lovely.

what are real engineering

A lot of my confusion stems from trying to understand what counts as being a real mechanical engineer. Or what I would define as success.

Here are potential answers:

  • Having the confidence to build parts that people can rely on and won’t fall apart
  • Creating a start-up that reaches the injection-molding stage and is cash-flow positive
  • Being able to use and even more so maintain and fix mills and lathes and other shop equipment
  • Being able to competently TA a class and answer technical questions
  • Getting As in my classes
  • Being knowledgeable like Amy and Shane and Charles in being able to tell you how to build and source almost anything
  • Being internet famous for technical things
  • Being able to fix anything that breaks
    • Knowing about cars
  • Being able to make awesome things from trash
    hi nick
    you should update your blog even more, i swear you’ve made at least three more instruments since then. of course I’m one to talk…
    • Being able to identify useful things from trash
    • Having professors like you and think you are competent (or at least not disappoint them)
    • Being able to help underclassmen
    Basically this is a compilation of thing I wish I were better at.
    One thing at a time, I suppose.
    Oh nyancat. This has turned into another of those whining about incompetence posts. It’s interestingly hard to convince myself to tout my competencies. I can only do it when I feel really angry or snarky. I remember Amy and try to convince myself to not constantly focus on my incompetency, but rather accept it and work to remedy it. So that I can be that competent female engineer that the younger me could point to and say, that is someone I would aspire to be. Which is another annoying thing, competency is inseparable from the issue of gender disparity for me. -___-;; It’s kind of distracting and rather useless in terms of actually becoming competent.

    possible competencies

    Things I am good at:

    • I’ve traveled. A lot. I will always have a fascination with cultures around the world.
    • I’ve worked with biology
    • Wanting to fix things. Being angry yet entertained at the state of the world.
    • Being enthusiastic about people learning to build things
    • Thinking in absurd ways
    • Having lots of different interests
    • I can speak and read Chinese
    • ?___? I have no idea. Nothing on here is technical competence…
    I’ll leave it an open question for now. In the meantime, I am going to go sleep in the sofa under my loft, which somehow makes me feel better (except then I don’t want to get up), and then wake up and finish my overdue essay. Oh, and talk to facilities about washing trash cans at 8:30 am.
    segue! hello there, trash cans behind the student center.
    something is really off about my solidworks dimensions. oh well.
    i felt silly for spending hours CADing nyancat. but after spending hours CADing a trash can (yes, I suck at CADing / CADing efficiently) I would happily go back to internet meme engineering. Also then I don’t have to look at my teammates’ CAD and feel terrible. Oh right, I’m supposed to feel inspired by other people’s work.
    speaking of nyancat, 2.009 professor wallace shows up in a nyancat shirt sometimes.
    speaking of nyancat part 2, one of my hallmates (ben katz) got contacted by the creator of nyancat. He legit engineered nyanhat thing.
    Speaking of classes…
    Strobe Lab 6.163
    Lab 5: Bullet Photography
    In other news, I have been making shiny strobe lab pictures, even if I’m neither building high voltage strobe circuits nor going to get more than a bare minimum B in that class.
    Bullet going through a stream of water. GIMP composite of four images, flipped horizontally.
    this was the setup for the water stream photos
    this was the setup for the LN2 carnation shots and shows location of the rifle (which we didn’t touch, the professor shot it)
    These pictures were with: Andrew Schlaepfer, Merritt Boyd, Monica Ruiz, and Prof. Bales
    They’re so pretty! This class doesn’t make me feel any more technically competent though.
    Well, anyway. Aside from classes and wondering how other people define competency, I’ve been mostly unproductive in terms of projects. My immediate project will be the persistence of vision poi project, and then I have two major goals (aside from getting a job or getting into grad school).
    • Help make sure the open source hardware bootcamp in China happens this summer
    • Implement my kits idea in some form, where a concrete engineering curricula is implemented using physical kits combined with online delivery of content
      (eek. I have to talk to a professor about this. Also this is my one chance of getting into grad school. Also, remind me to braindump about 2.007x sometime, which is the alternative to implementing this as my own startup…).
    • Actually document my projects. I harp on people to document their projects, but I don’t really have my own cohesive documentation scheme ^^;

    With respect to thoughts about school, here is a pretty well-known TED talk:
    A transcript can be found here: