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Thread: Position calculation

  1. #1
    Administrator T-1000 vikas's Avatar
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    Default Position calculation

    Well I was thinking of building a small home Robot using ITX that ICE recommended . If you know about ITX you know about what the platform is .

    So here is my problem ...

    The robot is the type shown in movies ... something which moved around in the house doing small stuff ( simple Voice REc and Synth etc ) goes from room to room and gives company etc ( i think u get my point ) . Now the problem . For the robot to move around easily in the house it has to have a mental map of the envoirnemnt ( simple XY map ) Now the robot can move in some valid XY points only . Now for the robot to go from point A to B it should know its current location is for that i can use Stepper motors , shaft encoders , some form of becons whatever . So if i stay on the gound and my Wheels dont slip i know my exact pos relative to my start ( can be some place on the map ) . Now suppose Wheels slip , I pick and place the bot some place else Now i want to know the robots pos on the map . So what do you think the best alternative ? . Remember it my house so i cant put some stupid beacons / lines /calibrating markers etc anywhere i like .

    I require some Idea :idea:

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    Administrator T-1000 rao's Avatar
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    Default hmmm

    what you can do in case your wheels slip is pick the bot up put it at the origin place on your map... and press reset...which will sent the robo tracking pointer back to the origin...

    I am sorry I am too sleepy... will reply something better tomorrow..

    Rao

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    Administrator T-1000 vikas's Avatar
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    Default but ....

    REmember i want my robot to be completely autonomus . Not some one who follows line . So i can touch thing one its switched on . It should take care of everything itself .

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    Default

    I've 2 beautiful solutions for u.:

    Hack an optical mouse.Theres' still research to be done on it[i mean use it for robotics].The plus point is ,u just hover it above the ground and get ticks[NO SLIPPAGE PROBLEM!!]

    the second is a bit far fetched and expensive,...GPS
    But u need 2 have a good reference point if ur movin short distances.
    check this thread:
    http://www.talkroot.com/showthread.php?threadid=5803

    some modules:
    http://www.totalrobots.com/access_fi...m....expensive
    http://www.commlinx.com.au/UV40.htm

    hope this helps.
    -ice
    //gerry

  5. #5
    Administrator T-1000 vikas's Avatar
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    Default well

    I thought of both solutions .

    Optical mouse - It need to be very close to groud --- I need some good ground clearance or it will just get stuct with simplest of bumps !!! Optical mouse dont work when even 2-3 cm off the ground

    GPS - The GPS gives a resolution is about 100 M which can be improved to about 15 meters if you use authorised Precision Positioning Service (PPS) . But still both are too big dimensions

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    Default

    DAMN!!!

    will think still
    How abt vision...with maybe landmarks on walls to guage its relative position
    -ice
    //gerry

  7. #7
    Administrator T-1000 vikas's Avatar
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    Default well

    If you did image processing ever ... Its really difiicult ... finding landmarks That will be difficult as hell .... So much processing and code will have to be written .. And it not easy !!! Well the robot will have to be good at image processing but still its very difficult !!! And i mean DifficulT :!:

  8. #8
    Guest

    Default Alternative to GPS

    http://www.phanderson.com/printer/compass/compass.html

    GPS is a costly alternative.... An electronic compass coupled with a little feedback from the encoders in the wheels can give you pretty good RELATIVE position....

    Position location is one of the most interesting problems in robotics.... Triangulation is one of the methods that is pretty well documented on the net... Google away!

    Also, let me remind you that every entry in the DARPA Grand Challenge failed - and they were all using GPS - REASON ?

  9. #9
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    That was a beautiful link,Guest[ what's ur name?]

    I think it will go into my christmas wishlist.

    Just one thing to point out....
    The vehicles in DARPA did use GPS ...true ,But u can't blame it.
    There were a number of other things too like obstacle avoidance problems.

    I have to read on triangulation though.
    Nice link once again.

    -ice
    //gerry

  10. #10
    Administrator T-1000 vikas's Avatar
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    Default hi

    I was also thinking on some similar line ...

    Using a Dipsmore compass to generate the oreintation of the robot and generating a rough map of the place using Sonar .. Then somehow compare that map to the one stored in memoryfor a beter location sensing . But its still a thought right now .

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