Servo, Stepper, Or closed Loop?

rwgast_logicdesign

So if I were to do an outdoors bot in this kind of terrain

What would be my best option for motors? A closed loop system is cool becuase you can use things like crazy drill motors etc if you need more power, although looking at what smaller motors can do I think big honkin 10 amp motors my be over kill! Ive also noticed there are geared servos out there, but Im not sure how fast these would go, and as far as steppers im completely clueless of there price to power range, looking at robot shop the biggest stepper is like 4vs, also to get a smooth drive you would have to implement micro stepping right? Basically im just trying to figure out the most cost effective option for a motor system where the posistion is controlled or and detectable. Gearing servos seems like the easiest choice but like I said im not sure of its power and speed. Im looking at the bot being somewhere in the 10lb range give or take 5lbs. My idea is just to use 4 ryobi drill motors with there gear box and batterys but like I said that may be over kill as the motors can draw up to 10 amps at 10v there pretty strong, ive also thought about these there very cost effective http://www.goldmine-elec-products.com/prodinfo.asp?number=G18980 and they have a backshaft!!

So for accuracy and power what is the best choice for a rover, I could look at specs till im blue in the face but as far as practical experience its mostly all with DC motors and a little servo stuff.

W9GFO

You need to decide what you want the robot will do. You have specified a weight of up to ten pounds which is a good start. How fast do you want it to go? What size wheels will you use? WIll it push or pull anything?

I think servos are too small for a 10lb robot unless you are okay with it moving really slow. Steppers are not very efficient so I would not use them. Drill driver motors can work well providing you size the wheel appropriately. Some have the added benefit of a built in clutch.

SRLM

I'd buy one of the Pololu Thumper robots. They're on special right now, and a great deal: http://www.pololu.com/catalog/category/43

But otherwise, for any robot of decent size you need to go with a DC motor, either brushed or brushless.

rwgast_logicdesign

Well honestly If i could really get build a heavy duty robot that can roll around the desert and mountains untended I would want to use some fairly large wide wheels, The idea would acually be to mix a 4 legged walker with a wheeled bot so it could climb things in its way. The bot would have for independent motors/servos/steppers etc.. at the "feet" this would be its main travel system. It would only walk to climb things and get unstuck. This bot would be a huge challenge but I think it would be the design I would really love to build the most. One of my issues is I dont know what the wheel set up is even called to do a little more research on it, I mean I understand how it works how to gear etc, but id like to know some more in depth info. And actually the more I think about it the leg joints might need pretty hi torque two, but they would need acuracy. lets say the thing weighed 20 libs and lets say each joint was 2 or three lbs stepper or servo which is more cost effective and effiecent.

Here is an example where i drew insperation from..
http://letsmakerobots.com/files/field_primary_image/Stair_Climber_3.jpg

And here is my idea

If someone could tell me what that sort of wheel set up is called id appreciate it

W9GFO

Here's a similar robot;