My neighbor stopped mowing lawns so I decided to build a robot. For many tasks including cleaning and painting. My requirements included
1) be sturdy enough to carry and guide a weed whacker
2) be able to move quickly on smooth terrain
3) be able to go up the various types of stairs and uneven land necessary to cut all my grass
Through suspension prototyping, I moved from aluminum for an indoor-outdoor robot, to 5/16 steel. to 3/8 steel for basically an outdoor robot. So this is a pretty heavy robot that needs some pretty strong motors. I had assumed I would use multiple brushless electric motors. Because that seems to be the standard for large-scale RC cars and such. Gas engines are a very sloppy power source. So far as I know, they are adjustable by throttle and gearing. Whereas electric motors offer much more precise control. For a nimble and precise robot.
But I would not even use a battery-powered weed whacker, that would be ridiculous and would suck miserably. I am worried that the motors I am going to purchase will require too much battery and will not last very long. And the necessary batteries will add so much weight. that the suspension will need to be sturdier, the engines stronger, and the batteries even larger, so that it might suck no matter what the combination.
Maybe electric power is only practical for the extremely easy scenario of a vehicle which goes on a flat, smooth road, or on rails. When I see those MIT guys testing that four-legged dog robot, for example, it is usually hooked up to power cables. How long can that beast really go on batteries? I saw a poster in the hardware store illustrating how many logs you can cut with a cordless electric chain saw. But I have thrown all my rechargeable tools in the trash, the cordless ones are a source of endless disappointment.
What do you think? Can a device like that robot dog, or anything where the weight is not babied by a smooth road, be very useful running on batteries?