1. OCAU Merchandise is available! Check out our 20th Anniversary Mugs, Classic Logo Shirts and much more! Discussion in this thread.
    Dismiss Notice

Lego Mindstorms - Advanced Robotics

Discussion in 'Other Toys/Hobbies' started by matthudson, Sep 4, 2008.

  1. matthudson

    matthudson Member

    Joined:
    Aug 26, 2006
    Messages:
    1,387
    Location:
    Charlestown, NSW (2290)
    This is a bit of information about the lego mindstorms kits, as well as a few of the more epic things I have run up.

    The Bricks
    There are two types of lego mindstorms 'bricks'. These are basically the control unit for the robot. Say hi to the rcx.
    [​IMG]
    The RCX features 3 inputs ,labelled 1, 2 and 3, to which sensors (light, touch, rotation etc) can be attached. It also has three outputs ,labelled A, B and C, to which motors or lamps can be attached. Additional features include an infra-red port (black bar that the top of the brick), a multipart display (between the input and output ports) and, on this brick, a power port capable of taking 9 to 12V DC.

    NOw onto its younger, but far more advanced brother. Say hi to the nxt
    [​IMG]
    Look, its brought a few of its friends along! Before I explain the purpose of the robot, lets look at its individual parts.

    [​IMG]
    This is the light sensor. It returns a percentage value, and can illuminate an object with a red LED or just use ambient light

    [​IMG]
    This is the NXT motor. It can rotate clockwise or anticlockwise. It also can measure the amount it has rotated.

    [​IMG]
    And this is the NXT. It has three outputs, labelled A, B and C, at the top of the brick. It also has 4 inputs, labelled 1, 2, 3 and 4, at the bottom of the brick. Additional features include a 100x64 LCD display, bluetooth and usb. This one is called FATSO, for no particular reason.

    Which now brings us back to the strange combination of parts in the original photo.

    Robot 1
    The first robot is actually a multi-purpose robot. Its first job is to act as a glorified etch-a-sketch (works best in high quality video)

    *note: I take no responsibility for any and all sound on any and all videos*
    The robot uses the rotation sensors inbuilt to the motors to measure change in position, which it then uses to draw a line.

    Its next function is to draw a graph based on a light sensor input. Once again best viewed in high quality


    Now, onto the next amazing (*cough*) lego monstrosity

    Robot 2
    [​IMG]
    If you can't tell from the picture, this is a remote control for another NXT robot. It uses the two motor rotation sensors to get power values, then sends them via bluetooth to the slave robot (not shown above).

    Here's a video, mostly of the slave robot as I don't have a third hand (that lego creation didn't work so well). Unlike the above two, this doesn't need to be viewed in high quality. But feel free to if you want to


    So, what is so epic about the previous robots? Nothing really, but the next one will blow your mind (hopefully)

    Robot 3
    For this robot, we say goodbye to the flashy NXT and return to its younger brother-the RCX

    [​IMG]
    And here it is, in all its glory, hooked up to a few bits and bobs making it a fully functional scanner (if scanners scanned slower than snails and only in black and white)

    [​IMG]
    This is the business end of the scanner. As you can see (or might not see) the scanner 'head' moves along the toothed rails. The whole device is capable of moving forward on two sets of caterpillar tracks mounted at the ends of the rails

    [​IMG]
    This is the underside of the scanner head. The blue thing in the middle of the image is the light sensor, and the whole head moves on the six small gears to the side. These gears are driven off a set of worm gears connected to the motor.

    [​IMG]
    And here is the head next to the rails. 'nough said really

    OK, so how does it go? Well, luckily for you I only recorded a single pass, so you are spared the agony of waiting three hours for the image to finish. Firstly, the video:


    Now, the image to be scanned:
    [​IMG]

    And finally, the result:
    [​IMG]
    Yes, I knows its a bit distorted, and the lines don't match up. The distortion is a robot issue, and the lines is a program issue.

    Okay, now the technical stuff:
    All these programs were coded in Robolab 2.9.4
    If you'd like a copy, just ask and I'll upload one somewhere
    To render the image, I coded a java program.

    Well, thats it from my wonderful world of lego inventions (for now at least...) I hope this has inspired you to gt out the old bricks and see what you can do with them
     
    Last edited: Sep 18, 2008
  2. glasnt

    glasnt Member

    Joined:
    Aug 9, 2004
    Messages:
    3,793
    Very nice post.

    I remember using Mindstorms with RCX to build soccer playing robots back in '01/'02 for a comp known as Robocup.

    Awesome :thumbup:

    The first years at Griffith U doing Programming I are using these to try and get concepts of programming ^_^
     
  3. OP
    OP
    matthudson

    matthudson Member

    Joined:
    Aug 26, 2006
    Messages:
    1,387
    Location:
    Charlestown, NSW (2290)
    Yeah, i got into robotics through robocup, and this year ended up coaching the teams my school put in. Good fun :thumbup:
     
  4. glasnt

    glasnt Member

    Joined:
    Aug 9, 2004
    Messages:
    3,793
    Awesome. I was the year before the guys that ended up in the world finals in '03/'04 from memory. We helped train them up on the RCX's, then they added metal robotics around the brains of the beast for extra awesomeness.
     
  5. Squeezer

    Squeezer Member

    Joined:
    Feb 25, 2002
    Messages:
    6,869
    Location:
    Adelaide
    I'd love to get a Mindstorms kit for my "kids " :D
    Looked into it a few years back but they were a bit $$ to justify
     
  6. R3Dl2ULZ

    R3Dl2ULZ Member

    Joined:
    Oct 26, 2006
    Messages:
    1,238
    Location:
    The Hills, Sydney
    It only makes me want it more :(
     
  7. underskore

    underskore Member

    Joined:
    Nov 5, 2002
    Messages:
    4,376
    Location:
    3198
    great work with the scanner & id love a copy of the code for the etch-a-sketch, i talked my dad into buying me an nxt kit but i havent done anything this exciting, but i do love being able to make a remote control vehicle that i can drive with my phone.
     
  8. OP
    OP
    matthudson

    matthudson Member

    Joined:
    Aug 26, 2006
    Messages:
    1,387
    Location:
    Charlestown, NSW (2290)
    They still are a bit expensive, but if you grab and old RCX kit it should be a lot cheaper :thumbup: Plus, there's not really that much more that the NXT does. Apart from bluetooth and the LCD display.

    I know that feeling. Its a shame that other kids need to use these kits, otherwise I'd have built a mech warrior by now :p

    I'll upload the code as soon as I can get a permanent host. Shouldn't take that long really. I should warn you, it will only work with ROBOLAB, not the lego mindstorms software.

    As for phone bluetooth, i haven't really looked into it much, mainly because I don't have a phone and I'm a RCX man myself. No reason that it couldn't be done though, good luck :thumbup:
     
  9. underskore

    underskore Member

    Joined:
    Nov 5, 2002
    Messages:
    4,376
    Location:
    3198
    soo, im just wondering if getting that etch-a-sketch code is still an option?
     
  10. OP
    OP
    matthudson

    matthudson Member

    Joined:
    Aug 26, 2006
    Messages:
    1,387
    Location:
    Charlestown, NSW (2290)
  11. Squeezer

    Squeezer Member

    Joined:
    Feb 25, 2002
    Messages:
    6,869
    Location:
    Adelaide
    Was watching an older 2nd hand Minstorm 2.0 Kit on Ebay last night and with 4 minutes to go was at $150 then in the last 3 minutes jumped up to over $300 :sick: in the last few minutes. Dont understand why people were bidding so much for a used older generation one when for $60 more you can get the NXT version and warranty
     
  12. Franko

    Franko Member

    Joined:
    Nov 1, 2004
    Messages:
    815
    Location:
    Fremantle, Perth WA
    I still have my old Mindstorms v2.0 (with RCX, motors, sensors and lots of other gear) and a spare RCX.

    Mindstorms kicks ass, havent used it in like 6 years.. I should crack it out and play with it one day!

    That NXT looks pretty advanced with bluetooth etc.. in order to get remote control going with the old RCX you have to use IR, which was always pretty flakey. My RCX still uses a serial port for comms as well :/
     
  13. occxlr8ed

    occxlr8ed Member

    Joined:
    Jan 2, 2007
    Messages:
    2,519
    Location:
    Melbourne
    Woah, lol. I got the 1.5 AGES ago when i was a kid, never played with it. Still ogt everything, i should pop it on ebay.
     
  14. OP
    OP
    matthudson

    matthudson Member

    Joined:
    Aug 26, 2006
    Messages:
    1,387
    Location:
    Charlestown, NSW (2290)
    The older kit I find is a bit more responsive than the NXT. Plus its a lot easier to build with than the NXT.
     
  15. Kermalius

    Kermalius Member

    Joined:
    Mar 15, 2002
    Messages:
    870
    does the NXT have enough power to implement a MIMO PID controller? Doing it on the RCX was a bit burdensome IIRC
     
  16. STx

    STx Member

    Joined:
    Oct 31, 2004
    Messages:
    106
    Location:
    Sydney
    Good work :D
    Here's a playlist of videos from when I did this in a first year intro to engo design course at unsw. This set is of a Robot Sumo competition we had where our robot Pwnasaurus won. We used the RCX kit as well and won even with some other teams using NXT.
     
  17. OP
    OP
    matthudson

    matthudson Member

    Joined:
    Aug 26, 2006
    Messages:
    1,387
    Location:
    Charlestown, NSW (2290)
    Yeah, I've always preferred the RCX simply because its easier to build from and seems to be a bit more responsive than the NXT.
     
  18. Squeezer

    Squeezer Member

    Joined:
    Feb 25, 2002
    Messages:
    6,869
    Location:
    Adelaide
    Just won a V 2.0 Mindstorm Kit from Ebay at a Much better price than the crazy stuff happening Pre Christmas.
     
  19. underskore

    underskore Member

    Joined:
    Nov 5, 2002
    Messages:
    4,376
    Location:
    3198
    NXT Noiseboxxx

    had a bit of spare time lately, and wanted to try something with the NXT...
    so im trying to build a faux-theramin/noisebox

    i've got most of the functionality happening, but i'm not ready to post it up yet (working on useable hardware design and code will need to be tweaked once thats finalised)

    but for the moment, its vitals are as follows.
    • ultrasonic sensor - frequency
    • optical encoder - volume
    • optical encoder - tempo
     

Share This Page

Advertisement: