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  • Matthewfl 1:08 pm on 28 July, 2012 Permalink | Reply
    Tags: comments   

    Comments about another state 

    This post was written over a number of days in a disjoint fashion. You were warned.

    Already in the first days of this vacation I have come up with a number of amusing comments and I felt that it was only right that they be recorded somewhere.

    First the air port that we flew into had something like two terminals. I was joking that there would be one person working TSA and when we came back through they would simply look at us and ask if we are going to blow up the plane and then let us through. I was somewhat close in that there were two people working TSA, however they did appear to have the basic requirements to be called TSA.

    Second when we got in the car the radio came on and started playing the most stereotypical country music came on and started saying “she thinks my tractor is sexy.” The next time that we turned on the radio it was a song about loving their front porch more than anything else.

    The place that we are going to for our volunteer activities was considerably farther away then originally expected. As a result my mother was driving somewhat above the speed limit. As she claims this is her first ticket in a while, gg. No California roles here.

    We are the volunteering on the blackfoot reservation this last week. It has been somewhat slow, it appears that it has something to do with the native culture. They believe that it will end up working out and stuff.
    The main thing that we have been doing this week is helping the community college get themselves together for their next semester. They are quite small with only 500 students and a few classrooms.
    When we are not helping Getty the college ready, we have been interacting with the community.

    Today we are leaving the volunteering group. We are going to be driving up and around to do a ‘normal’ vacation.

     
  • Matthewfl 10:25 pm on 2 August, 2011 Permalink | Reply
    Tags: FFT, Perfect Horizon   

    Eliminating vibration on the Perfect Horizon 

    For this summer I have been interning with Motion Picture Marine which designs and builds the Perfect Horizon.  The prime use of the Perfect Horizon is to keep a camera level with the Horizon.  This is especially important when working on boats and shooting off into the distance.  In the near future it is also expected that keeping a camera shot level with the horizon will become even more important because 3D moves on average have shots that are twice as long, and any movement in the image is many times more likely to cause motion sickness of the audience.

    ph-dsc5776-2-1024x661

    The way that the Perfect Horizon works is by compensating by movements of the boat or moving vehicle using two motors, to move the platform in the opposite direction.  The problem comes from when the Perfect Horizon is not mounted on a stable platform.  This is because when a 100 pound camera is mounted on top, there is a large deal of inertia, and thus the platform underneath ends up getting pushed.  If the platform can be moved even a little bit, then the Perfect Horizon will detect this and attempt to compensate as it was designed to do.  In turn this causes the system to begin to vibrate.  (This problem can easily be seen on a crane arm, or any poorly designed mount)

    This problem can basically be broken down into two major components.  The first being the detection of the vibration, without miss detecting normal operation.  And the second is modifying the internal parameters of the system to prevent it from vibrating.

    For my first attempt at detecting the vibration I just attempted to use simple signal processing filters.  This ended up working on my test rig as it was a stationary platform.  In moving to a moving platform I began to notice some problems with the solution.  The first being that it would miss detect jolts or changes in motion as vibration.  This was simply unacceptable as this would degrade the quality of the system and prevent it from doing the job that it was designed for.  With some internet research, I found out that jolts are visible on all frequencies while vibrations are only on a select few.  (link)  This lead to using fourier transform for processing the signal.  What a fourier transform basically does is it converts signals in the time domain into signals in the frequency domain.  This basically means that when looking for a vibration, we need only check for outliers in the set of data.  This has turned out to be a better solution, and combining it with simple check to ensure that there are enough samples that indicate vibration there has not been any false positives as of thus far.

    The second problem came in with modifying the gain of the system to prevent it from vibrating.  I believe that part of the problem with the vibration comes from the fact that the system produces thousands of tiny jolts while moving, this is because the system will determine where it wants to move to, and then it will move to that point up to a maximum speed.   Once it has reached that point, it will stop and wait until the next sample is ready.  The solution here is to slow down the motors so that they do not reach the end before the next sensor reading.  The obvious answer of just always slowing down the motors will not work, as then the system would not be able to deal with the larger movements because the motors would be moving too slow.  In implementing the solution the motors are only slowed down when the system determines that it is vibrating.  This essentially gives the system some form of adaptive control over the internal parameter used in the system.

     
    • Steven Jorgensen 9:51 pm on 6 August, 2011 Permalink

      Nice! Pretty legit internship in my opinion. This “Perfect-Horizon” camera has a lot of control theory embedded in it. Good job for integrating fourier transforms.
      The gain solution is also pretty interesting. Typically you only need one type of gain value, but given that it needs to act in 2 different ways depending on the situation, it makes sense to have a condition there to be adaptive.

  • Matthewfl 6:37 pm on 13 June, 2010 Permalink | Reply
    Tags: ,   

    June 12, 2nd day of SAS 

    Again on the Semester at sea there has all ready been a great deal.  This time I did get up in time for breakfast.

    After breakfast I went to the lecture by Sandra Day O’Connor about the history of the high court I had the joy of being able to eat lunch with Sandra Day O’Connor.

     
  • Matthewfl 8:58 pm on 11 June, 2010 Permalink | Reply
    Tags: learning, ,   

    June 11, 2nd day of summer break 

    This is the seconds day of summer break and I am spending at least the first part on the semester at sea, for 4 days are their “Global engagement forum.”

    This has been there first day of there really being any actives.  My day started with getting up really late and missing breakfast.  Then I went and lissioned to Julian Bond talk for about 90 minutes about the past.  After all of this I then found myself at lunch.  Right after lunch I was in somewhat of a private interview with Julian Bond finding out even more of his personal view.  Then that quickly lead to the second lecture about the sustainability of society with three experts.  Followed with a 45 minutes panel of Q&A.  I must admit that I was falling asleep during this event as I am still adjusting to the  3 hours off from California time.  After coming out of a nap I went to dinner and then to a viewing of Beyond the call, followed by a Q&A with the basically everything of the movie.

    What a day.

     
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