Drive for my new robot

[banana_man]

Hello all,
I am having some problems with the drive system in my new F/W. I am running windscreen wiper motors with 9cm dia wheels. My first problem is that the motors are not a left/right pair, but rather identical motors. Since the motors run faster forwards than backwards, the bot will end up doing circles. How could I fix this. Would a giro work?
Question number two: I have heard that wiper motors short out on a metal chassis. Is this true?

Thanks for your help

[Mouldy]

Re: Drive for my new robot

does the motor body have flats on it? or is it perfectly round? if there the round type, Take the motor apart, so u have the motor can with the magnets and clips inside. mark the position of the magnets, then cut a plate of metal or wood that fits between the aposing magnet retaining clips, twist the metal or wood while holding the can in a vice..

Rotating the magnets will alter the speed of the motor for forwards or reverse depending on the direction you twist it.

You'll have to just play about with it, it wont need much of a movement of the magnets to make a big change in the speed of the motor. about 10degree's or so and you will notice the speed differance, (listen for the pitch of the motor while running to get a ruff idea of how close your getting)

Alternatively a gyro will work and be easyer yes.

this is worth doing aswell http://www.rrc.dannysrobots.co.uk/07-1.jpg
http://www.rrc.dannysrobots.co.uk/07-2.jpg

[joey_picus]

Re: Drive for my new robot

http://rrc.dannysrobots.co.uk/

Can't remember if there's anything there about rotating magnets but there's a load of stuff about wires and speeds :P

[RogueTwoRobots]

Re: Drive for my new robot

I think Rex talked about magnet rotation in Issue 38 or 39, but I got fed up scanning those articles that I decided to just stop at Issue 37 when the robot was complete.

[banana_man]

Re: Drive for my new robot

First of all, thanks very much for your help.

I have been thinking about the use of windscreen wiper motors, and come to the conclusion that they're more trouble than they're worth. I think it's better to start with something that works, rather than fighting with something that doesn't from the outset. They have mismatched speeds, they're heavy ( 1kg each+steel box section frame= overweight) and are huge.
Now I've got that out of my system...
Does anybody know of any motors which would do the job, considering that they will need to be quite slow, but with loads of torque?

Thanks

[psycho_fling]

Re: Drive for my new robot

speed 900s on some gearing that suits your needs

[banana_man]

Re: Drive for my new robot

I did think about speed 900s, but then there is the problem of cost. Although not that expensive in themselves, they need a gearbox and decent ESC(s), neither of which I have. I need to finish this bot in 5 weeks, and would like to if possible use some pre-made motor-gearbox combos to save time. Can anyone think of anything like that which I can get hold of within the next few weeks, and won't cost a bomb.

Thanks

[typhoon_driver]

Re: Drive for my new robot

drills

[calumco]

Re: Drive for my new robot

the B&Q drills.

[banana_man]

Re: Drive for my new robot

I've thought long and hard about the drill option, and they just don't seem to cut it. With 18cm dia wheels, they will go at a completely uncontrolable speed, and although this is easily sorted with spektrum gear, there is the torque issue: there will be no chance of getting under opponents, let alone pushing them around. One idea I had was to put in further stages of gearing, and I am looking into that. My main problem is my severe lack of experience with creating my own gearing. I wouldn't know what to do with a tensioner if you stuck it under my nose . If someone who knows what they are doing could explain how to do extra gearing to me, I would be very grateful.

Thank you to everyone who has offered their help so far.

[mattan]

Re: Drive for my new robot

Will this do it ? http://www.robotmarketplace.com/product ... _main.html

Both expensive and unexpensive motors whit gears.

Mats

[mattan]

Re: Drive for my new robot

http://www.robotmarketplace.com/store.html ---------look under motors.

Sorry for the post before are an incompleat adress, bad forum web adress handeling.