Quote:
Originally Posted by RyanCahoon
Agreed, but in that case, since D and N are being applied at different points on the lever arm, equation 3 needs to incorporate that.
Either:
- analyze it from a force perspective, where you have to consider all 3 forces (D, reactive force from wheel axle bearings, reactive force from drive axle bearings), or
- analyze it from a torque perspective, which allows you to choose your origin so that r*F is 0 for one of the forces, but you have to include the radius for the other two
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Looking at these three forces:
- D acts on the wheel/gear and reacts on the drive gear.
- force from wheel axle bearings acts on the module arm and the chassis
- force from drive axle bearings acts on the module arm and the wheel/gear
There is no single part which experiences all three of these forces. Note that D is eventually transmitted to the chassis through a combination of the wheel axle bearings and the motor bearings (and cluster gear bearings if you have a multi-stage gearbox), so it is actually applied to the chassis as linear forces rather than a torque. Changing the gear ratios will result in different proportions of D being applied at each bearing. I do not see how this affects what D is at the wheel gear, as long as it does not actually lift one side of the robot off the floor and change θ.