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memsic 2125 — Parallax Forums

memsic 2125

scary_botscary_bot Posts: 32
edited 2006-07-19 02:49 in Robotics
I was wondering if there was a way to use the memsic 2125 to detect if the boebot is stuck in a position unable to move. If there is I'd love to see any sample code that might be avalible demoing the idea. This would solve the never ending problem of my bot getting stuck in a position where the sensors are unable to sence the object trapping it... arrrg!

Comments

  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-07-18 11:28
    scary_bot -

    I doubt that the Memsic accelerometer will give you what you want. The two best methods I know of for detecting linear motion are: 1) an odometer or 5th wheel, and 2) GPS.

    Regards,

    Bruce Bates

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    Post Edited (Bruce Bates) : 7/18/2006 11:56:32 AM GMT
  • cdubcdub Posts: 26
    edited 2006-07-18 16:22
    I'm not sure if this is appropriate for your application (new user), but there may be some nugget of helpful information in this people-based application.· I did find the accelerometer easy to work with following advice on this board.

    Cdub
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-07-18 18:11
    If stuck would cause a predictible vibration data set, the Memsic can recognize it.

    What I would presume is that stuck means that the tilt on both axis wouldn't change, but there would be some activity that would be recognized as 'noise'. First sample for the presence of noise to indicate the servos are trying to move [noparse][[/noparse]causing vibration], then sample with averaging to get a measure of tilt. Do it all again and if the tilt has not changed a bit -- you have stuck.

    The real problem here is to get your noise level identified, the minimal level at which tilt changes due to motion, and a good averaging sample.

    The mandown function may not be what you really want. It serves a very different purpose.

    BTW, I have a motorcycle helment here that I was considering putting the Memsic atop and fooling around with transmitting data via IR to a reciever.· The mandown function could find that useful in transportation [noparse][[/noparse]such as Subway train operators].· They would no longer have to hold onto a 'deadman's throttle' for long periods.· People could have more physical freedom, but be monitored.

    I think it my also link with my PC as a mouse if I can hack into my RF wireless mouse and transmit to the reciever unit.
    In that way, you could tilt your head to move the cursor.· I haven't figured out a 'click', but if it was programed to the page up, page down, move left, move right functions· - you could read lengthy texts [noparse][[/noparse]like E books] while having your hands free for other tasks [noparse][[/noparse]like knitting socks].


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    "If you want more fiber, eat the package.· Not enough?· Eat the manual."········
    ···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

    Post Edited (Kramer) : 7/18/2006 6:20:22 PM GMT
  • cdubcdub Posts: 26
    edited 2006-07-18 19:03
    In reference to BBates' reply there is a good article in this month's Servo magazine called "Mobility to the Max".· It·explained odometry etc, and it showed how to calculate distance traveled. Not sure if it helps in your case with spinning wheels.



    Mobility to the Maxx - Part 4
    by Chris Cooper

    Last month, in our quest to create the coolest and fastest mobile robot on the planet, we gave the E-Maxx improved motor control and some new capabilities. Now it can move at very low speeds and maintain a constant speed in almost any type of terrain. It can also record the distance traveled and move at a specified distance and velocity.
  • PARPAR Posts: 285
    edited 2006-07-19 01:19
    scary_bot said...
    I was wondering if there was a way to use the memsic 2125 to detect if the boebot is stuck in a position unable to move. If there is I'd love to see any sample code that might be avalible demoing the idea. This would solve the never ending problem of my bot getting stuck in a position where the sensors are unable to sence the object trapping it... arrrg!
    More information on the following would help identify the nature of your problem:

    - "stuck"?· How stuck? I.e., what is the bot doing while stuck?

    - "in a position"?· What position(s)?· I.e., what about its position is related to its inability to move?

    - "unable to move"?· No movement of the wheels? Of the bot? No shaking, vibrating, rattling --no movement whatsoever?

    - "the sensors"?· Which sensors are those? I.e., what type(s) of sensors and where are they located, and what information are they programmed to deliver?

    - "the object"?· What kind of object(s) are "trapping" the bot? In what way(s) is the bot trapped?

    - "trapped"?· Trapped how? And, what circumstances lead up to becoming "trapped"?

    Designing a solution means describing and understanding the problem sufficiently.


    PAR
  • scary_botscary_bot Posts: 32
    edited 2006-07-19 02:49
    Thanks so much guys. All of your commits are very helpfull. But this is all way above me, as such I am giving up on the idea. Thank you for all your help.
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