Power and couple with several motors

[floppi]

Hi,

I've got a question about power or couple with several motors and the capacity of the accu.

If I plug two motors to my nxt, will I have more power or the power of the accu will be divided because two motors are plugged ?
And what if plug the 3 motors ?

By example : Will I have more strength for a forklift if I dedicated three motor for lifting, heavier loads will be possible ?

[mattallen37]

Each motor driver (or "motor port") is rated for 1 amp.

Three motors on three ports would increase mechanical power, but probably not three motors on one port (at least not nearly as much).

The batteries would also effect the power. Three motors won't be three times as powerful as 1 motor, because of the voltage drop due to the load.

Edit: what do you mean by "accu"?

[h-g-t]

Using gears will give you an immediate advantage if you only want to use one motor.

If you put in a 2:1 gear ratio you will get almost double the torque but at half speed.

You get less than half the torque because of the friction between the gears and the axles/ mountings.

See
http://sariel.pl/2009/09/gears-tutorial/
http://www.texbrick.com/articles/gears.pdf
http://www.cs.swarthmore.edu/~meeden/robots/lego.html
http://www.google.co.uk/url?sa=t&rct=j& ... IEI9RVUDtA

All these writers advise against using the worm gear because of high friction.

However, I replaced a long gear train with a worm gear and one 40 tooth wheel, ending up with a higher gear ratio and less friction.

Even less once I applied molybdenum grease.

[mightor]

Edit: what do you mean by "accu"?

Battery pack. http://en.wikipedia.org/wiki/Accu_(battery)

- Xander

[HaWe]

an accumulator is a rechargeable battery.
E.g., in German we mainly call only a non-rechargeable battery just "battery", otherwise mainly "accumulator" or shortened "accu".

[floppi]

Sorry for my english, it's possible I use wrong words, i'm french.

I try to build a dragster wich will have the front wheel on the air permanently, motor power will be set accordingly to the distance from the ground with the ultrasonic sensor, At this time I have two motors for rear wheels. I Wonder if a third motor would increase power or not.
Finding a right solution between gear ratio, number of motor, load balancing of the dragster is a bit difficult

[mattallen37]

Interesting, I've never before heard of them being called an accumulator.

If the motors are on different ports, then a third motor will increase mechanical power.

You want the vehicle to balance on the rear wheels, using an ultrasonic sensor to measure the tilt, and motor power to adjust the tilt? That is very unlikely to happen. The ultrasonic sensor update rate is far too slow, and the precision is 1cm (not to mention the inaccuracy). IMO the best way to measure tilt (or rate of tilt) would be to use a gyro sensor.

[h-g-t]

"Interesting, I've never before heard of them being called an accumulator."

This is a term little used nowadays but I think it was originally used to distinguish between dry-cell (zinc-carbon) and rechargeable wet-cell (lead acid) batteries.

Around 1950 my father had a wireless ("radio" nowadays) and I remember him taking the accumulator down to the local electricians' once a week for a recharge. This had a glass case so always had to be treated with great care.

At that time our village had no mains electricity so everything else in the house was run on coal, paraffin and the rare (because expensive) dry-cell.

Not heard of it being used to describe modern 'dry-cell' rechargeable batteries though - you live and learn!

See also http://en.wikipedia.org/wiki/Accumulator_%28energy%29

[mightor]

Accu is a common term for a multi-cell rechargeable battery unit in The Netherlands. "Accu" is so much shorter than "oplaadbare batterijen". Non-Dutch speakers are also less likely to swallow their own tongue whilst trying to pronounce the former.

If you have tried to pronounce the latter, don't worry, help is on the way as soon as I am done charging my oplaadbare batterijen.

- Xander

[floppi]

Interesting, I've never before heard of them being called an accumulator.

If the motors are on different ports, then a third motor will increase mechanical power.

You want the vehicle to balance on the rear wheels, using an ultrasonic sensor to measure the tilt, and motor power to adjust the tilt? That is very unlikely to happen. The ultrasonic sensor update rate is far too slow, and the precision is 1cm (not to mention the inaccuracy). IMO the best way to measure tilt (or rate of tilt) would be to use a gyro sensor.

Ok, it seems that all I want to build recently is impossible to create