Package frc.robot.subsystems.swervedrive2.swervelib.math

Class SwerveMath

java.lang.Object

frc.robot.subsystems.swervedrive2.swervelib.math.SwerveMath

public class SwerveMath
extends Object

Mathematical functions which pertain to swerve drive.

Constructor Summary

Constructors

Constructor	Description
SwerveMath()

Method Summary

Modifier and Type	Method	Description
static double	applyDeadband(double value, boolean scaled, double deadband)	Algebraically apply a deadband using a piece wise function.
private static double	calcMaxAccel(edu.wpi.first.math.geometry.Rotation2d angle, double chassisMass, double robotMass, edu.wpi.first.math.geometry.Translation3d chassisCenterOfGravity, SwerveDriveConfiguration config)	Calculates the maximum acceleration allowed in a direction without tipping the robot.
static double	calculateAngleKV(double optimalVoltage, double motorFreeSpeedRPM, double angleGearRatio)	Calculate the angle kV which will be multiplied by the radians per second for the feedforward.
static double	calculateDegreesPerSteeringRotation(double angleGearRatio, double pulsePerRotation)	Calculate the degrees per steering rotation for the integrated encoder.
static double	calculateMaxAcceleration(double cof)	Calculate the practical maximum acceleration of the robot using the wheel coefficient of friction.
static double	calculateMaxAcceleration(double stallTorqueNm, double gearRatio, double moduleCount, double wheelDiameter, double robotMass)	Calculate the maximum theoretical acceleration without friction.
static double	calculateMaxAngularVelocity(double maxSpeed, double furthestModuleX, double furthestModuleY)	Calculate the maximum angular velocity.
static double	calculateMetersPerRotation(double wheelDiameter, double driveGearRatio, double pulsePerRotation)	Calculate the meters per rotation for the integrated encoder.
static edu.wpi.first.math.geometry.Translation2d	limitVelocity(edu.wpi.first.math.geometry.Translation2d commandedVelocity, edu.wpi.first.math.kinematics.ChassisSpeeds fieldVelocity, edu.wpi.first.math.geometry.Pose2d robotPose, double loopTime, double chassisMass, double robotMass, edu.wpi.first.math.geometry.Translation3d chassisCenterOfGravity, SwerveDriveConfiguration config)	Limits a commanded velocity to prevent exceeding the maximum acceleration given by calcMaxAccel(Rotation2d, double, double, Translation3d, SwerveDriveConfiguration).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SwerveMath

public SwerveMath()

Method Detail

calculateAngleKV

public static double calculateAngleKV(double optimalVoltage,
                                      double motorFreeSpeedRPM,
                                      double angleGearRatio)

Calculate the angle kV which will be multiplied by the radians per second for the feedforward. Volt * seconds / degree <=> (maxVolts) / (maxSpeed)

Parameters:

optimalVoltage - Optimal voltage to use when calculating the angle kV.

motorFreeSpeedRPM - Motor free speed in Rotations per Minute.

angleGearRatio - Angle gear ratio, the amount of times the motor as to turn for the wheel rotation.

Returns:

angle kV for feedforward.

calculateMetersPerRotation

public static double calculateMetersPerRotation(double wheelDiameter,
                                                double driveGearRatio,
                                                double pulsePerRotation)

Calculate the meters per rotation for the integrated encoder. Calculation: 4in diameter wheels * pi [circumfrence] / gear ratio.

Parameters:

wheelDiameter - Wheel diameter in meters.

driveGearRatio - The gear ratio of the drive motor.

pulsePerRotation - The number of encoder pulses per rotation. 1 if using an integrated encoder.

Returns:

Meters per rotation for the drive motor.

applyDeadband

public static double applyDeadband(double value,
                                   boolean scaled,
                                   double deadband)

Algebraically apply a deadband using a piece wise function.

Parameters:

value - value to apply deadband to.

scaled - Use algebra to determine deadband by starting the value at 0 past deadband.

deadband - The deadbnad to apply.

Returns:

Value with deadband applied.

calculateDegreesPerSteeringRotation

public static double calculateDegreesPerSteeringRotation(double angleGearRatio,
                                                         double pulsePerRotation)

Calculate the degrees per steering rotation for the integrated encoder. Encoder conversion values. Drive converts motor rotations to linear wheel distance and steering converts motor rotations to module azimuth.

Parameters:

angleGearRatio - The gear ratio of the steering motor.

pulsePerRotation - The number of pulses in a complete rotation for the encoder, 1 if integrated.

Returns:

Degrees per steering rotation for the angle motor.

calculateMaxAngularVelocity

public static double calculateMaxAngularVelocity(double maxSpeed,
                                                 double furthestModuleX,
                                                 double furthestModuleY)

Calculate the maximum angular velocity.

Parameters:

maxSpeed - Max speed of the robot in meters per second.

furthestModuleX - X of the furthest module in meters.

furthestModuleY - Y of the furthest module in meters.

Returns:

Maximum angular velocity in rad/s.

calculateMaxAcceleration

public static double calculateMaxAcceleration(double cof)

Calculate the practical maximum acceleration of the robot using the wheel coefficient of friction.

Parameters:

cof - Coefficient of Friction of the wheel grip tape.

Returns:

Practical maximum acceleration in m/s/s.

calculateMaxAcceleration

public static double calculateMaxAcceleration(double stallTorqueNm,
                                              double gearRatio,
                                              double moduleCount,
                                              double wheelDiameter,
                                              double robotMass)

Calculate the maximum theoretical acceleration without friction.

Parameters:

stallTorqueNm - Stall torque of driving motor in nM.

gearRatio - Gear ratio for driving motor number of motor rotations until one wheel rotation.

moduleCount - Number of swerve modules.

wheelDiameter - Wheel diameter in meters.

robotMass - Mass of the robot in kg.

Returns:

Theoretical maximum acceleration in m/s/s.

calcMaxAccel

private static double calcMaxAccel(edu.wpi.first.math.geometry.Rotation2d angle,
                                   double chassisMass,
                                   double robotMass,
                                   edu.wpi.first.math.geometry.Translation3d chassisCenterOfGravity,
                                   SwerveDriveConfiguration config)

Calculates the maximum acceleration allowed in a direction without tipping the robot. Reads arm position from NetworkTables and is passed the direction in question.

Parameters:

angle - The direction in which to calculate max acceleration, as a Rotation2d. Note that this is robot-relative.

chassisMass - Chassis mass in kg. (The weight of just the chassis not anything else)

robotMass - The weight of the robot in kg. (Including manipulators, etc).

chassisCenterOfGravity - Chassis center of gravity.

config - The swerve drive configuration.

Returns:

Maximum acceleration allowed in the robot direction.

limitVelocity

public static edu.wpi.first.math.geometry.Translation2d limitVelocity(edu.wpi.first.math.geometry.Translation2d commandedVelocity,
                                                                      edu.wpi.first.math.kinematics.ChassisSpeeds fieldVelocity,
                                                                      edu.wpi.first.math.geometry.Pose2d robotPose,
                                                                      double loopTime,
                                                                      double chassisMass,
                                                                      double robotMass,
                                                                      edu.wpi.first.math.geometry.Translation3d chassisCenterOfGravity,
                                                                      SwerveDriveConfiguration config)

Limits a commanded velocity to prevent exceeding the maximum acceleration given by calcMaxAccel(Rotation2d, double, double, Translation3d, SwerveDriveConfiguration). Note that this takes and returns field-relative velocities.

Parameters:

commandedVelocity - The desired velocity

fieldVelocity - The velocity of the robot within a field relative state.

robotPose - The current pose of the robot.

loopTime - The time it takes to update the velocity in seconds. Note: this should include the 100ms that it takes for a SparkMax velocity to update.

chassisMass - Chassis mass in kg. (The weight of just the chassis not anything else)

robotMass - The weight of the robot in kg. (Including manipulators, etc).

chassisCenterOfGravity - Chassis center of gravity.

config - The swerve drive configuration.

Returns:

The limited velocity. This is either the commanded velocity, if attainable, or the closest attainable velocity.