SwerveModuleState angle range

[viggy96]

I was looking at the swerve drive kinematics documentation on WPILib (Swerve Drive Kinematics — FIRST Robotics Competition documentation), and it was unclear whether the SwerveModuleState class used [0, 360] or [-180, +180] for the module angle.

[Ryan_Blue]

It takes a Rotation2d, which can take any angle with Rotation2d.fromDegrees(); 0 degrees is facing forward.

[viggy96]

I’m aware that it’s a Rotation2d object. Let me rephrase.

If I’m at 0 degrees, and I turn the wheel left and right by 1 degree, should that correspond to -1 and +1 degree?

Or should it be +359 and +1 degree?

[kgzak]

Rotation2d.fromDegrees(-1) == Rotation2d.fromDegrees(359). They are the same thing.

[Ryan_Blue]

It shouldn’t matter since whatever you’re giving the SwerveModuleState to should be able to handle angles properly, and getSin and getCos will return the same.

Just out of personal curiosity, I ran a test to see what SwerveDriveKinematics returns and it looks like it bounds them within (-180,180).

@kgzak

Rotation2d.fromDegrees(-1) == Rotation2d.fromDegrees(359)

Semantically,

Rotation2d.fromDegrees(-1).equals(Rotation2d.fromDegrees(359))

But your point holds.

^{yes I did actually check this, the equals method just checks that the sin and cos are within a tolerance of each other.}