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[wpimath] Document drift from desaturating discretized chassis speeds (NFC) (#7741)

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This commit is contained in:
Joseph Eng
2025-02-03 10:46:18 -08:00
committed by GitHub
parent 18321e5551
commit 296986397b
4 changed files with 48 additions and 5 deletions
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12
wpimath/src/main/native/include/frc/kinematics/ChassisSpeeds.h
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@@ -59,7 +59,11 @@ struct WPILIB_DLLEXPORT ChassisSpeeds {
* y-axis, and omega * dt around the z-axis).
*
* This is useful for compensating for translational skew when translating and
* rotating a swerve drivetrain.
* rotating a holonomic (swerve or mecanum) drivetrain. However, scaling down
* the ChassisSpeeds after discretizing (e.g., when desaturating swerve module
* speeds) rotates the direction of net motion in the opposite direction of
* rotational velocity, introducing a different translational skew which is
* not accounted for by discretization.
*
* @param vx Forward velocity.
* @param vy Sideways velocity.
@@ -94,7 +98,11 @@ struct WPILIB_DLLEXPORT ChassisSpeeds {
* y-axis, and omega * dt around the z-axis).
*
* This is useful for compensating for translational skew when translating and
* rotating a swerve drivetrain.
* rotating a holonomic (swerve or mecanum) drivetrain. However, scaling down
* the ChassisSpeeds after discretizing (e.g., when desaturating swerve module
* speeds) rotates the direction of net motion in the opposite direction of
* rotational velocity, introducing a different translational skew which is
* not accounted for by discretization.
*
* @param continuousSpeeds The continuous speeds.
* @param dt The duration of the timestep the speeds should be applied for.

10
wpimath/src/main/native/include/frc/kinematics/SwerveDriveKinematics.h
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@@ -335,6 +335,11 @@ class SwerveDriveKinematics
* the absolute threshold, while maintaining the ratio of speeds between
* modules.
*
* Scaling down the module speeds rotates the direction of net motion in the
* opposite direction of rotational velocity, which makes discretizing the
* chassis speeds inaccurate because the discretization did not account for
* this translational skew.
*
* @param moduleStates Reference to array of module states. The array will be
* mutated with the normalized speeds!
* @param attainableMaxSpeed The absolute max speed that a module can reach.
@@ -370,6 +375,11 @@ class SwerveDriveKinematics
* the absolute threshold, while maintaining the ratio of speeds between
* modules.
*
* Scaling down the module speeds rotates the direction of net motion in the
* opposite direction of rotational velocity, which makes discretizing the
* chassis speeds inaccurate because the discretization did not account for
* this translational skew.
*
* @param moduleStates Reference to array of module states. The array will be
* mutated with the normalized speeds!
* @param desiredChassisSpeed The desired speed of the robot