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Subject: 
Re: NXT Newbie "Is it possible" question
Newsgroups: 
lugnet.robotics, lugnet.technic
Date: 
Thu, 26 Aug 2010 16:35:03 GMT
Viewed: 
4258 times
  
In lugnet.robotics, Kevin L. Clague wrote:
In lugnet.robotics.nxt, Brian Davis wrote:
In lugnet.robotics.nxt, Kevin L. Clague wrote:


I like it!  As they say "There's more than one way to skin a cat".

I work on computer servers that have 128 CPUs per chip and 512 CPUs per pizza
sized box, and I knew that there is no true parallelism here with the NXT :)

I like your design, because it seems more accurate because it grabs the time at
which the system sees the touch sensor pressed.  One point of inaccuracy due to
lack of parallelism.

My solution has two points: one at recording the button was pressed, and the
other in the loop deciding who got what place. For example if software just
checked lane 4 to see if it finished, and then lane 4 finishes, then lane 3
finishes, and software was busy checking lane 1 then 2, it could incorrectly
report lane 3 as placing before lane 4.  It all depends on how quick the loop is
(I have no idea!)

Kevin

Well, I've built a 2 sensor version of Brian's idea using parallel sequence bars
(I tried your idea Kevin, got stuck, then Brian chimed in).  I just did some
testing by building a rig to press the 2 sensors "simultaneously." I was able to
get them to within 1 msec of each other.  The data seemed to favor sensor 1 as
far as timing.  I tried pressing the sensors in all different manners to avoid
any favoring of 1 sensor based on method.  I even swapped out the cables so they
were all the same length (only going as low milliseconds, it shouldn't matter).
Overall, while not "perfect", close enough for what I am doing.  I don't
anticipate many races being that close.

Maybe I'll just get 3 more NXT bricks ;)

Chris



Message has 1 Reply:
  Re: NXT Newbie "Is it possible" question
 
(...) *NOW* you're thinking like a Mindstorms person ;). Seriously, I'm glad it's working. The 1 ms difference could be due to a lot of things... but if it's not that critical, then it's not a problem. (14 years ago, 27-Aug-10, to lugnet.robotics, lugnet.technic)

Message is in Reply To:
  Re: NXT Newbie "Is it possible" question
 
(...) I like it! As they say "There's more than one way to skin a cat". I work on computer servers that have 128 CPUs per chip and 512 CPUs per pizza sized box, and I knew that there is no true parallelism here with the NXT :) I like your design, (...) (14 years ago, 26-Aug-10, to lugnet.robotics, lugnet.technic)

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