(Complete Beginner) Simple Robot?

[Oscillation]

I've heard about using old window screen wiper motors to make a robot, what else do i need to buy if i want to use 2 motors on a body so that it can be controlled with a remote?

I'm a complete beginner so any help is gratefully accepted.

[airman00]

what exactly do you want to build

what size, how much power, what application, etc.


to drive motors you need something called a motor driver

[Oscillation]

More of a remote control vehicle but robot suites its name more, just like a two wheeled controlled robot for now.

What size depends completely on the electrics side of things but i don't know exactly how large. About the size of a dinner tray i'd say.

How much power... Again, i'm a complete beginner so i wouldn't know how much power i need, its gotta be able to carry about 5kg of weight though.

Application? I don't understand, if your talking computer program then i'm not really after using a computer unless thats the easiest way.

[airman00]

by application I mean what will it be used for , what the robot will do , whats the purpose, etc.

now how much money are you willing to invest into this project?

your setup should be two motorized wheels( one motor for each wheel) and one caster wheel in front.

to get you started research the  following:
H bridges
DC Motors
Geared Motors
R/C Motor Controller

[Rand alThor]

You could just use the motors from an old inkjet printer...

...and you could make a motor driver from scratch.

Where do you live, anyway? I live out in the middle of nowhere and so I go looking in the desert for old junk people throw away... I just desolder the components(at least I started today) and (plan to) recycle them. I tell you, an old TV is a marvelous find...

[airman00]

be careful rand alThor the capacitors inside those things may still be charged and will deliver a nasty shock  . To uncharge them simply short the capacitors.

[polar bear6]

I tell you, an old TV is a marvelous find...

and potentially a lethal one
you should look into what sorts of electricity tv's and crt screens contain, its pretty awesome, but if you touch the wrong wire it will smell barbecue all the way to vegas. (since you live in the desert it cant be that far right?)

i found you some links to how to discharge them, i have personally gotten some shocks myself, not from big things only cameras and the wall, but they hurt like a female dog, so watch out and be safe.

http://www.stickycarpet.com/pinx/md.html
http://www.wikihow.com/Discharge-a-CRT-Monitor

yea and only use one hand.

[polar bear6]

great now i feel dumb

[Rand alThor]

Yeah, there are a couple whopper capcitors on there.. like as big as the drink you get in a McDonalds kids meal...

But since it looks like it was made in the 50s, I figure I'm safe (somewhat) for now.

[I LIKE PI]

Oscillation, how about just using an old rc vehicle and attaching it to a microcontroller? Since you are a beginner, it will probably be easier than finding new motors and wheels to make a robot. Also, if you still want to make it from scratch, continuous rotation servos are probably the easiest, but you will normally have to pay about 10$ for one.

[quinacia]

and potentially a lethal one
you should look into what sorts of electricity tv's and crt screens contain, its pretty awesome, but if you touch the wrong wire it will smell barbecue all the way to vegas. (since you live in the desert it cant be that far right?)

I have to agree with the polar bear on this one Rand. For two reasons. The first is that you seriously could be killed--and that sucks. The second is that if you do discharge it safely there is likely to be a very loud noise that may well convince your mom that this electronics stuff is way too dangerous.

[Oscillation]

Oscillation, how about just using an old rc vehicle and attaching it to a microcontroller? Since you are a beginner, it will probably be easier than finding new motors and wheels to make a robot. Also, if you still want to make it from scratch, continuous rotation servos are probably the easiest, but you will normally have to pay about 10$ for one.

I've thought about this but i've got some old mini fridges which i think the fan motors might be of some use?

Also, i seem to be the only one but i'm from England so things should be cheaper than how you state... e.g. 10$ = £5ish

Thanks

EDIT:

You could just use the motors from an old inkjet printer...

...and you could make a motor driver from scratch.

Planning on using old mini fridge fan motors but how'd i make the motor driver?

[Oscillation]

I've been looking at things and would like to know if these would work and how would i make them work...

http://www.trossenrobotics.com/store/p/5385-Parallax-Futaba-Continuous-Rotation-Servo.aspx
http://www.trossenrobotics.com/store/p/5718-Pololu-Ball-Caster-with-3-8-Plastic-Ball.aspx
http://www.trossenrobotics.com/store/p/3384-Neoprene-Foam-Tire-1-75-D-x-0-5-W-pair-.aspx

What things here would i need?
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=radio+control&x=0&y=0#

[airman00]

first off:

you dont need to be a continuos servo , you could buy a regular servo and modify it easily and save like 20 bucks. Continuous servos are regular servos that the company modifies by hand. It's the same as you modifying it.

also is that the amount of torque you need in the servo


as for the R/C part why not just purchase a toy R/C car and hack it for your needs - its extremely simple , I've done it many times and can help you out with that.

[bens]

you dont need to be a continuos servo , you could buy a regular servo and modify it easily and save like 20 bucks. Continuous servos are regular servos that the company modifies by hand. It's the same as you modifying it.

The Parallax continuous rotation servo costs around $12, so it's hard to say you can save $20 by buying something else.  I believe Parallax has these servos specially made for them by Futaba, which means they can provide them for pretty much the same price as a standard servo of the same quality.

- Ben

[Oscillation]

Ugh so many servos! Just taken the fridges apart and the fan motors aren't sufficient in anyway other than cooling (der) so im going with the servo idea.

If i buy a cheap rc car, will any servo work with it or do i have to buy the car then tell you guys what all the stuff in it is and you can point me in the right directions?

Thanks

P.S. The fridge body's are very sturdy so i'm thinking of using the door for the chassis
or the shell.

[I LIKE PI]

One thing you need to look into when you take out motors from things like refrigerators is often times the voltage is much higher than you can use in the robot (unless you have an on-board generator or thousands of dollars in rechargeable batteries). A good thing about using an RC car is you no longer need to worry about motors. All you have to do is attach the existing motors to your microcontroller. Depending on what exactly you want, you can use either a motor controller (usually 30$ and up) or you can use transistors which are only a couple dollars. The difference between the two is that motor controllers can give you the speed you want, while transistors can't, but it's much cheaper.

One difference with using an RC car instead of using servos is an RC car doesn't use differential drive. In case you don't know what that is, it's where each wheel works separately. You can make turns by staying in the same spot if you like by making the two servos go opposite directions. With an RC car, you must move forward or backward to make the turn because all the wheels must go in the same direction.

So what exactly are you going for with this robot? Are you trying to make it as cheaply as possible, or are you trying to make a really nice robot and have plenty of money to spare? Also, do you know what exactly you want it to do?

[airman00]

you dont need to be a continuos servo , you could buy a regular servo and modify it easily and save like 20 bucks. Continuous servos are regular servos that the company modifies by hand. It's the same as you modifying it.

The Parallax continuous rotation servo costs around $12, so it's hard to say you can save $20 by buying something else.  I believe Parallax has these servos specially made for them by Futaba, which means they can provide them for pretty much the same price as a standard servo of the same quality.

- Ben

lol well said. Hitec sells continuous servos for 20 dollars more

[bens]

Those might be a ripoff, I can't really say.  Then again, they might be very high quality servos, or perhaps they have extra features that standard servos don't.

- Ben

[airman00]

all the hitec continuous servos are is a modified regular servo. They don't manufacture them continuous ( except for that parallax one )