motors?

Johnny-5

i am assuming the motors (vs servos) are used for speed and torque? I am wanting to build a tracked robot... i like the walkers but they are too slow for my taste. I would like it to run outdoors to. I am familiar with the servos but dont know much about using motors, i will have to have a motor controller right? is that just a D-to-A decoder? are the motors acurate compared to the servos?

i am not sure what to use... i want to use servos, simply because i know how to use them and could implement them easly, however im thinking the motors may be able to accomplish what im wanting better.

LSB

Simple answer is to use a serial motor controller: Output serial data to control speed and direction to each motor; you're all set--assuming you've kept the amp rating of the controller higher than the amp rating of the motors (watch stall current especially). More involved, but cheaper is to investigate "H-bridge" on google or Parallax site and start a learning curve. First investigate inductive load ICs and finally transistors made for the purpose. I find the SN754410N chip handy for small loads ~.5 amp--it's a cheap (DK $1.83) single chip answer that handles most of my needs (and fits my lack-of-knowledge curve nicely). Also, check out Pulse Width Modulation (PWM commonly) as it's somewhat weakly implemented on the low end BS chips.

Steve Joblin

why not use both?

I have found a great set up is to use the Pololu Dual Serial Motor Controller along with "super modified" servos.·

What's a "super modified" servo you ask?· It is a servo with all the electronics ripped out, so it basically a small DC motor connected to some gears... you can over-volt them a bit if you don't go too crazy or run it for extended periods of time... I've put 9 volts through them and haven't burned a motor yet!

The Pololu Dual Serial Motor Controller is a very good, very inexpensive device that is perfect with a Parallax stamp... it comes in several "forms" (surface mount, pre-built, or kit form).· check it at http://www.pololu.com/products/elec.html#motocon