hey everyone. I really appreciate your inputs.
At 900+ rpm, you are going to have one quick tracked bot. Below are two h-bridges that might fit your needs.
I think there are a number of options on the site that sells the motor $) - have you looked through these?
for the two quotes above, they don't seem to be able to do differential steering. so how do i achieve differential steering? Or am i missing something here?
There isn't going to be any cheap and easy options when dealing with motors with such high stall currents. The site you're getting the motor from does provide a number of speed controllers that operate at those currents and higher, but they start getting pricey. Building a large robot is a pricey endeavor though, no way around that really unless you can hand build virtually every component of the robot, and then you're really just trading financial cost for time cost.
As for the appropriate size motor for your robot, that depends on a variety of factors. How fast you want the robot to go. What kind of tire setup you are using. Treaded setups require a lot of torque for differential steering as you are doing a lot of skidding and need to be able to overcome the static friction between the treads and the ground, and even this friction will vary from surface to surface. For the same reason 4 wheels differential steer system will require more torque than 2 wheel setups. 6, 8, and more wheels will all require more torque as well.
And another question, how do I know how much torque I will need for my tracked robot which weighs around 20KG or less? Is the motor located in the link I provided a bit of an overkill for such robot?
Two questions you need to answer:
1) What is the radius of your drive wheels?
2) If you tied a rope to your robot and pulled on it, how much force would you need to apply before the robot lost traction and started sliding?
Using a hypothetical answer of 10kg of force to slide the robot and wheels of 5 cm radius, then you'd need a motor with 10kg * 5cm = 50kg/cm of torque.
To jraskell - Thanks for your advice. Actually I don't need my robot to be fast, I just need it to be around 0.5m/s. For the acceleration part, I don't really know what I need. What if I do want my robot to go on an incline, like maybe 20 degrees? Thanks in advance for your advice.
To Chagrin - I always read about the tire radius and stuff, but how do I determine my radius when I'm using tracks? I have these servos which I am going to modify to continuous rotation. The model is Seiko PS050. Do you think it is strong enough? And do you have any idea how I can check the stall current of the servo?
THANKS GUYS! (: