Finding the Perfect DC Motor for Your Small Robotic Platform

[jedishrfu]

I'm looking for a DC Motor to power a small 50lb robotic platform with maximum speed of 10mi/hr.

What should I be looking for?

I've made some basic assumptions of 8" or 12" diameter wheels and so the rpm rating should 420 rpm and 300rpm respectively to attain 10mph. I plan to use at least two motors for steering capability so each needs to handle 25lb load max.

What I'm looking for a commercial DC motor capable of driving the platform and its associated gearbox if needed.

So far I've seen the Segway RMP which uses brushless DC motors but doesn't provide the spec for it. I figure it would be too powerful since the Segway platform is 200lb load capable.

 

[fleebell]

Try searching for electric scooter motors/repair parts. There are many places on the net that sell them. They come in many sizes and a smaller one would work for your description of needs. A 250-300w version would probably work well for you.

These are normally brushed motors. Some even come with reduction gears built into them. They come in 12/24/36/48 volt and from about 100 to 1000 watt versions. All kinds of sprockets and belt pulleys are available for them also.

I use them quite often in projects because they tend to be much less expensive than commercial/industrial small lower voltage motors.

You can get smaller brushless versions of bike motor hub drives also. I think about 250 watts is about as low as they go and up to a couple of horsepower if you want to spend the money. Those can be direct or internal gear drives. They would probably also be a little more difficult to use with a robotics platform due to the mechanical differences but could be used.

It this is a home type project consider looking at Craigslist or something like that. You can often pick up the smaller electric scooters very cheaply from those sources. I've been getting most of my motors, controllers, throttles,etc... that way for about 1/3 of what I can buy them off the net.

I've found 90% of the time, the only thing wrong with the scooter is dead batteries and parents simply don't want to spend the $50-$125 needed depending on to replace them. The majority of them have low hours on them too as they almost always have the original set of tires on them and are rarely even halfway worn out when I get them.

 

[jedishrfu]

Thanks for the scooter idea. I've been looking at Baldor motors (pricey) and thinking of battery drill replacement motors but then the issue of gearing came in. The scooter idea is appealing because they are geared and the right speed too. I might even be able to use the tires as well. Thanks.