How Does A Robot Turn
Most of our robots use brushed DC gear motors to power the wheels or tracks. Many of them are 4WD or tracked platforms that use tank style steering or skid steering. This means that the wheels/tracks on either side of the robot turn at different speeds which guides the robot in the direction of the side that is moving slower. Furthermore, by moving all the wheels/tracks on the left side one direction and the right side the opposite direction, the robot can turn in place.
Since the robot has to "skid" to steer, friction is the major factor for sizing your components (most importantly, the motors). The more the robot weighs, the harder it is to turn. The higher the friction coefficient (deep grass, carpet), the harder it is to turn. The lower RPM motors have lower speed, but more torque for easier turning. The default options listed for our robot kits are what we recommend as a good starting point. Contact us if you need help selecting options or need custom configuration.
Most of our robots use skid steer. Conventional steering is discussed here.