Re: NXT Newbie "Is it possible" question

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