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Voyager-- An autonomous outdoor robot
I was both inspired and challenged by Steve Hassenplug and his Green Monster creation(http://mindstorms.lego.com/nxtlog/ProjectDisplay.aspx?id=559789c9-9d1f-4355-9ffb-fae34b98c4aa) to build a self-navigating outdoor robot of my own. Voyager is the result of tons of prototypes and failed experiments. The heart of Voyager is a 3-motor articulated steering design. One motor drives both wheels on the rear axle through a differential. The front wheels are driven individually by the other two motors. This allows me to use all 3 NXT motors for drive power, not waste a motor for steering like on a car.

Outdoor performance:
Sorry, I don't have any pictures of Voyager outdoors yet, but I have tested it and it drives GREAT! It is so much fun to watch. Grass, gravel, pavement, dirt, Voyager handles them all with ease. It can even climb up hills and over some obstacles. All this on the LEGO rechargeable battery pack. Imagine what it could do with regular alkalines!

Posted by:

 jbrost76

Created:

 21 March 2008

Rate:

 

Tags:(?):

 voyager, jbrost76, outdoor, gps

The articulation point

The articulation point allows Voyager both to bend in the middle to steer AND allows the two end to twist. The first picture is of the articulation point. It uses a turntable for the twist joint. The articulation joint is just forward of the turntable (right of the turntable in the picture). Picture #2 shows how the twisting action allows one set of wheels to go up over an obstacle while all 3 other sets of wheels stay on the ground.

The Bluetooth GPS

Here is the bluetooth GPS module. It is mounted inside a cradle using those little rubber pieces from the NXT kit to hold it snug. NXT-G cannot read messages from a bluetooth GPS right now. Some people have worked towrd getting NXT-G to do it, but it is not easy. Rather than trying to do that myself, I decided to change to another programming language, RobotC.

The Program

Right now, Voyager has two modes in its program. In "manual" mode, it is driven remotely using a mindsensors's PSP-NX sensor and Playstation 2 remote. In this mode, pushing up & down on the right analog joystick moves Voyager forward and backward. Left & right movements on the same joystick turns Voyager left & right. Pressing the L1 button on the PS2 controller switches Voyager into "auto" mode. As soon as Voyager enters this mode, it takes a reading from the compass sensor mounted just behind the front wheels. It then proceeds to drive straight along this same heading until I switch it back to manual mode. While in auto mode it continuously monitors the heading values from the compass sensor and automatically steers right and left to maintaing the correct heading. I programmed all this in NXT-G. The next step is to incorporate the bluetooth GPS that is mounted at the front just ahead of the compass sensor. To do that, I changed programming lauguages to RobotC. I did not upload the NXT-G program because it caused me to go over the 5MB/project limit on NXTLOG (the .rbt is 3.3 MB on its own).

Comments

48 comments

  • Hanif553

  • Awesome robot dude. It's really advanced. Please post the program and a LDD file please.

  • Posted 1891 days and 13 hours ago


  • TK-847

  • Awesome!!! That's a really good robot! I like how you did the articulation point. I would like to see the programm but if it's to big you don't have to post it. But you could make pictures (screenshots) of it and discribe it a little more. Very impressive!

    TK-847

  • Posted 1891 days and 12 hours ago


  • kirkpthompson

  • Great project! Also, check out LeJOS for an alternative programming enviroment. http://lejos.sourceforge.net/

  • Posted 1891 days and 6 hours ago


  • NXTizzy

  • This is incredible, I want those wheels! Great idea with the twisting. You should submit it for some sort of challenge, it'll win.

  • Posted 1891 days and 5 hours ago


  • matoro555741

  • cool.were did you get the wheels from?

  • Posted 1891 days and 5 hours ago


  • LegoManIAm94

  • Can you post the program please?

  • Posted 1891 days and 4 hours ago


  • Juggs_H

  • Great job, it looks really stable.

    Good luck with the GPS.

  • Posted 1891 days and 4 hours ago


  • Murcielago53

  • Wow nice robot, I think that hassenplug's green machine has met its match. The articulation joint is very nice!

  • Posted 1891 days and 4 hours ago


  • alecmcalecmcalec

  • is the controler wireless and the infra red sensor picks up the signals?

  • Posted 1891 days and 4 hours ago


  • NXDave

  • WOW! Great articulated robot!

    NXDave.

  • Posted 1891 days and 4 hours ago


  • legolunatic652

  • That is so amazing! you can do almost anything with that... oh that would be so cool if it could read gps. That is an awsome structure! I would love to have a robot like that its sooooo cool

  • Posted 1891 days and 3 hours ago


  • StillBuilding

  • This is soooooooooooooooooo cool!! Where did U get all the green wheels? And please post the program then comment here so I know. Can U give me some tips on how 2 build somthing like this? Once again this is AWESOME!!!

    StillBuilding - A fan.

  • Posted 1891 days and 0 hours ago


  • drinkdrug

  • what shall i say....

    this robot is really cool! i like the design u made on it, i will never be able to make something like that... EVER!

  • Posted 1890 days and 23 hours ago


  • ChickenJoe25s

  • Supercool!! I give it a 10+++++++.

  • Posted 1890 days and 22 hours ago


  • timmynoah

  • I really want a program for it.

  • Posted 1890 days and 20 hours ago


  • victor288596

  • please post the program somewhere cuz' I want to see it

  • Posted 1890 days and 18 hours ago


  • mad1s792

  • Awesome. If only I had the time, patience and imagination to do stuff like this.

  • Posted 1890 days and 11 hours ago


  • asdf123eyeofi

  • how did you do that all and yes i would like the program

  • Posted 1890 days and 8 hours ago


  • Firebird468

  • That's amazing! It looks extremely sturdy.

  • Posted 1890 days and 8 hours ago


  • gamefreak741

  • Great robot! Just one question, did you get the wheels from the Exo-force set? If not could you tell me where you got them?

  • Posted 1890 days and 4 hours ago


  • woops555

  • wow! that is swwweeet! judjing by the tutntable, i can already tell how big it is!

  • Posted 1890 days and 2 hours ago


  • NXTea

  • ive been trying to get my dad to buy a psp-nx sensor . How did you make the middle so flexible. Did you make it with a universal joint ?

  • Posted 1890 days and 2 hours ago


  • Scottnxt

  • Nice robot!!!!! amazing by the way what is the Bluetooth Module u used (make/model)?

  • Posted 1889 days and 20 hours ago


  • jbrost76

  • Some Answers: Scottnxt... no bluetooth used
    NXTea: I used a turntable and some triangular shaped pieces... see the pictures
    thedolphindude: the PSP-Nx is the sensor. I got it from mindsensors.com
    gamefreak741: They are the wheels from the exoforce set #8108. I got mine from a very generous friend. You can always try bricklink.com to see if someone has them for sale.

  • Posted 1889 days and 6 hours ago


  • jbrost76

  • More Answers: 222Doc, thanks for the compliments. No, I haven't had any problems with the turntable yet. I think the reason is that at full articulation (side to side) the front and rear wheel surrounds actually hit before the joint reaches its full side to side range of motion. Vertically the front & rear parts seem pretty well balanced, so it hasn't pulled apart that way either. I might have just gotten lucky with the design.

  • Posted 1889 days and 6 hours ago


  • BIG_RED_1

  • he he he that is one fine robot there. I also wish I have the time, patience and imagination to make such awesome robots like this one. great work 96 out of 100!

  • Posted 1888 days and 16 hours ago


  • Dracalot

  • wow that is great. very well designed.!!!!!!!!

  • Posted 1887 days and 7 hours ago


  • Rasmussen

  • could you try to post an ldd plez?

  • Posted 1883 days and 1 hour ago


  • blue-engineer007

  • we all really do want the program

    its got to be big!!!!!!!!!

  • Posted 1880 days and 18 hours ago


  • Murcielago53

  • Is mindsensors certified by lego? And would you recomend getting a complete PSP-NX system (the cost is well over $100) and a compass sensor from hitechnic? Very nice robot anyways.

  • Posted 1877 days and 1 hour ago


  • jbrost76

  • Murcielago53: To my knowledge, Mindsensors products are not certified by LEGO. But I have yet to have a problem with them, I would have no problem recommending their products. As to the PSP-Nx, Mindsensors sells both the sensor individually and a sensor + controller combo. The sensor + controller is $54.95 USD. I have always liked HiTechnic's products. Long story short, either company you want to do business with, I think you're going to be ok.

  • Posted 1873 days and 18 hours ago


  • Dahari1

  • Amazing! Please make a seperate project with the program!

  • Posted 1873 days and 0 hours ago


  • ET1400

  • I like the color and the wheels

  • Posted 1872 days and 23 hours ago


  • dlevy

  • Wow. I just the the movie posted on nxtasy. Can you provide more information on the GPS bluetooth device. I.E. what brand and also the accuracy. From the movie looks like the vehicle as times turned just a few inches from those marker flags.
    Thanks. Very cool

  • Posted 1852 days and 6 hours ago


  • yo_face

  • VERY COOL can u make building instructions so i can build that :) :D

  • Posted 1850 days and 19 hours ago


  • LegoManIAm94

  • Is Mindsensors PS2 Controler 100 percent compatabe and 100 safe.

  • Posted 1837 days and 17 hours ago


  • boey195

  • wow, great men. i hope u can teach me how u did it? I also would like to do it.

  • Posted 1836 days and 11 hours ago


  • boey195

  • wow, great men. i hope u can teach me how u did it? I also would like to do it.

  • Posted 1836 days and 11 hours ago


  • nxtbuilder678

  • can u post an ldd of the articulation joint???
    the ones ive made are too flimsy to be effective and ive been trying for months.

  • Posted 1814 days and 23 hours ago


  • jbrost76

  • nxtbuilder678... keep an eye on this project... I added two new pictures to the articulation point step that will show you how I built it. Sorry I don't have time to put together a LDD for it.
    LegoManIam94: Mindsensors products are NOT approved by LEGO, so I am hesitant to say they are 100% safe & compatible. That being said, I have NEVER had a problem with my PSP-Nx. I can't comment on their other products, I don't have any of them.

  • Posted 1811 days and 0 hours ago


  • Rhomil

  • wow! manueverability AND GPS! looks awesome too!

  • Posted 1784 days and 16 hours ago


  • hn888

  • awesome!!!you can also put a wireless camera to send images from the robot.

  • Posted 1775 days and 10 hours ago


  • action_puny

  • Hey Jbrost, This really inspired me.

  • Posted 1727 days and 1 hour ago


  • pizzaking40

  • You are a lego god... you inspire me so much.

  • Posted 1371 days and 3 hours ago


  • DamaCynXT007

  • i agree pizzaking40, you're awesome jbrost76

  • Posted 1349 days and 8 hours ago


  • WJAJ

  • If you break the program int myblocks, you could post it

  • Posted 755 days and 4 hours ago



  • foton_mndp

  • This is BEAUTIFULL design. I like it. Have you tried it with on 4 wheels instead 8 ?

  • Posted 388 days and 5 hours ago


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