Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: Polaris on November 29, 2006, 06:56:00 AM

Title: [R]obot [Neo]phyte Needs he[p]
Post by: Polaris on November 29, 2006, 06:56:00 AM
Hi everyone,

    i need help in robotics construction. i will like to build a underwater robot, i had done some reading but i am not sure how to get the entire project going... ???

    At this point, i had managed to put together a micro-controller kit minus the actually writing of code and burning into the micro-controller. I am not sure where should i start -> from the mechanical structure construction or from the electronics. Reason being the structure must be able to contain the micro-controller on the card plus the electronic stuff (e.g. power supply, motors etc) whereas from the other hand, should i concentrate on putting together the electronic components first, the entire electronic functionality? Pls kindly advise me!!

   I also have been thinking, should i start off from building a robot that can run on land before it goes into water to build up my knowledge? ??? ???
   
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: JonHylands on November 29, 2006, 07:40:30 AM
   I also have been thinking, should i start off from building a robot that can run on land before it goes into water to build up my knowledge? ??? ???

I would strongly advise that you do this. Underwater robotics is about as hard as it gets, and its not a good place to be debugging electronics or figuring out communications and such.

Build something that cruises around your floor, and then once you've got that stuff working properly, think about underwater again.

- Jon
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: Polaris on November 29, 2006, 09:52:45 AM
Thanks Jon for your great advice... :) :) guess i have not thought of that

  it can be quite tempting to build exotic robots without knowing the fundamentals...think i should reread the guidance..need to hold my horses  :) :)
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: dunk on November 29, 2006, 12:12:39 PM
yup.
i would completely agree with Jon.
most robot builders fail on their first project because they make things too complicated too soon.

my first robot was doomed to failure because i made things too complicated.
i decided i wanted the bot to be able to map the room and plot a path so i had loads of sensors and a lot of mathematical routines running on the processor.
the main problem though was i just picked motors that were too big.
the battery life sucked, it went too fast to be controlable and the interference caused by such big motors made my controller behave eratically.

my 2nd robot was far more successful after applying the leasons i learned the first time.
it was driven by 2 smallish servos and had only limited sensors but could still find the beacon on it's battery charger within a few minutes from anywhere in my (small) house.

you'll hear loads of similar stories from amateur robot builders.
start simple, learn and progress.

now with more experience, i'm back trying to make a fast robot that can map the room but i could never have done as well if i had not built more simple bots in the past.
i'm doing much better this time round so don't give up on that underwater bot entirely....

check these for future inspiration:
http://web.ticino.com/Submarine/
http://web.ticino.com/Submarine/E1_page1.htm

hapy building!

dunk.
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: JonHylands on November 29, 2006, 01:06:34 PM
check these for future inspiration:
http://web.ticino.com/Submarine/
http://web.ticino.com/Submarine/E1_page1.htm

And of course, if you need even more inspiration, my AUV is fairly well documented:

http://www.huv.com/uSeeker

- Jon
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: Admin on November 29, 2006, 01:14:46 PM
i completely agree with Dunk and JonHylands. i had similar experiences during my n00b days.

what you can do is decide what kind of systems you want on your underwater vehicle, and build the prototypes of those on the land vehicle. for example, get motor drivers that will work on both your land vehicle and underwater vehicle. this will save you time and money in the future when you make the 'upgrade.'

i am currently working on my first underwater vehicle, and lemme tell you, its a whole new ball game . . .

as for which system to start with first . . . none. what you need to do first is understand your requirements (forces, goals, sensor objectives), and then lay out what you need to achieve those goals. think outside the box. the best solution is the easiest. then you go through a long iterative process until all your system designs fit together . . . me being a mechanical engineer i tend to focus on the mechanics because it is my strongest point, but im sure a computer scientist instead would spend more time on software solutions, etc . . .

keep us updated!
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: JesseWelling on November 29, 2006, 09:28:12 PM
That's why I went with prepackaged mechanical solutions. You really need to play to your strengths when
making a bot on your own. Sure I could try to design my own robot from the ground up, but better to start
with some pre-existing mechanics for me and work from that.

(http://www.cs.montana.edu/~wellingj/images/tachikoma.jpg)
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: Polaris on November 30, 2006, 02:14:15 AM
Thanks everyone, it is great motivation and rewarding to learn about the perils and thrills of robot building...btw anyone has any link to simple robot building? have been googling but can't find one which explicity tells me the step by step to construct one...it will be great if i can find electronic schematics of the linkage of the microC (aka microcontroller) and the rest of the components...

For now, see attached pict for what i have in mind.



   +Vcc-----(M)----Motor Driver-------[           ]----+Vcc
                                                [ microP ]
   +Vcc-----(M)----Motor Driver-------[           ]
                                               [            ]
                                   o--------- [            ]-----------o Photoresistor

Btw how can i attach my pict? unable to attach using the Attach function

 
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: Admin on November 30, 2006, 08:08:56 AM
Quote
btw anyone has any link to simple robot building? have been googling but can't find one which explicity tells me the step by step to construct one
The only step-by-steps robots I am aware of are the kits you can buy online. They supply all the parts and code for you, too. But where is the fun in that?  :P

Quote
Btw how can i attach my pict? unable to attach using the Attach function
I have banned images above certain file sizes and image dimensions. It will tell you the requirements when you attach.
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: Kohanbash on November 30, 2006, 09:03:15 AM
Old RC cars make great platforms for land robots. All you need to do is cut some wires and connect your micro controller.
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: JesseWelling on November 30, 2006, 12:07:12 PM
Old RC cars make great platforms for land robots. All you need to do is cut some wires and connect your micro controller.


Yes and no. r/c cars are harder to drive than tanks. This has a lot to do with being able to change a tanks heading without changing it's [x,y] coordinates. I'd say every ones first robot should be tank style. But you ar correct: R/C servos and speed controlls are easy to work with.
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: Admin on December 01, 2006, 01:48:57 PM
i hacked an el-cheap steering rc car a few years ago for a bot . . . but it failed cause the chassis had poor gearing, poor motors, couldnt breaking going down hills, etc . . . it couldnt even handle the smallest hills . . .

also hacked a $20 tank style rc, and it worked really great except on concrete, on which it refused to rotate . . .  :-\
it was actually my fastest robot (meter a second, sucessfully going around objects), and someday ill write something on it . . .

if you hack an rc vehicle, get something over $80-ish, with nice geared motors. and yea, tank rc styles are easier to program than the steering types.
Title: Re: [R]obot [Neo]phyte Needs he[p]
Post by: JesseWelling on December 01, 2006, 02:04:29 PM
for your first robot that can' be build upon latter I recomend something from here
http://www.budgetrobotics.com/
They have really good and cheep designes.