Im currently working on a project for a lawn mower robot and need some help with motor selection and mounting of the motors.
We're not sure to go about using 2 motors out back and a free moving wheel up front, or 4 wheel drive. We estimate the robot to be about ~20 lbs or less, and our goal is 1 foot/second speed.
We have no experience building a mechanical system like this so we messed up the first time around. We built a frame, mounted the motor to the frame, and then the hub to the motor shaft which connected to the wheel. That was it. This ran for a little bit but then 2 of the motors seized because of the weight being supported by only the motor shaft.
So we're trying to figure a new approach to actually mounting the wheels/motors so that the weight wont destroy the motors, and also looking into possibly new motors because we're returning the 2 that are currently still working.
These were our original 4 motorshttp://www.robotmarketplace.com/products/0-B231.html
We're thinking of now getting 4 of these insteadhttp://www.pololu.com/catalog/product/1107
Can somebody recommend a better motor choice for our application? 12v, 1ft/second speed, going through grass, robot weight ~20 lbs or less, low cost.
Should we go with a 2 wheel or 4 wheel design? Would either be fine?
Also, we're now thinking of mounting the motors like so:http://yfrog.com/f/evimag0386aj/
Will this avoid the weight of the robot being forced on the motor shaft?