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Unread 17-05-2014, 22:41
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Re: Coaxial Swerve Derivation with Paired Modules

Quote:
Originally Posted by Oblarg View Post
Yes; I meant incorrect compared to what is actually physically happening.
What is actually physically happening is quite complex, and the model provides 3 parameters to attempt to model it: Kf, Kro, and Krv.

You can set the values of these parameters to whatever you believe best reflects the physics.

Wind resistance depends on vehicle speed, not wheel speed. The force required to plow through the carpet arguably depends more on vehicle speed than wheel speed. You can use Krv to attempt to account for those effects.

Quote:
the physics are pretty different when you're slipping the wheels from when you're rolling.
That is true, and the friction model used attempts to account for these differences. Friction models are notoriously tricky. In this model, I used a "standard" static/kinetic friction model... so when the wheels are slipping, the torque on the wheels is constant at uk*normal_force*radius, and the wheels will be spinning at whatever speed that corresponds to on their torque vs speed curve, at the voltage derated for resistance losses in the circuit. When the vehicle speed finally catches up to wheel speed, the friction model transitions to static friction.