Swerve Gear Box

[Ether]

Originally Posted by PAR_WIG1350

That would not be unicorn drive.

Yes, it would. A Unicorn drive has exactly 3 degrees of freedom: two translational and one rotational. Typically, these 3 motions are all specified with respect to the same reference point on the vehicle, usually the center of geometry of the wheel pattern.

Any desired motion of the vehicle, including making the vehicle revolve around an arbitrary external point while simultaneously rotating about its own center of geometry, can be commanded by specifying the (time varying) values of the above mentioned 3 degrees of freedom.

One example is given here, which shows how to convert an Ackermann steering command into the 3 degrees of freedom.

You can also control center of rotation in a unicorn drive which adds 2 more variables.

The phrase "adds 2 more variables" should not be interpreted to mean "adds 2 more degrees of freedom". There are only 3 degrees of freedom.

Specifying an external point around which you want the vehicle center-of-geometry to instantaneously be revolving is simply a different way to specify the vehicle's instantaneous 2D translational motion. The interface presented to the driver should be as intuitive as possible for the types of vehicle motions the driver wants the vehicle to perform.