Represents the speed of a robot chassis. More...

#include <frc/kinematics/ChassisSpeeds.h>

Public Member Functions
constexpr Twist2d	ToTwist2d (units::second_t dt) const
	Creates a Twist2d from ChassisSpeeds.

constexpr ChassisSpeeds	operator+ (const ChassisSpeeds &other) const
	Adds two ChassisSpeeds and returns the sum.

constexpr ChassisSpeeds	operator- (const ChassisSpeeds &other) const
	Subtracts the other ChassisSpeeds from the current ChassisSpeeds and returns the difference.

constexpr ChassisSpeeds	operator- () const
	Returns the inverse of the current ChassisSpeeds.

constexpr ChassisSpeeds	operator* (double scalar) const
	Multiplies the ChassisSpeeds by a scalar and returns the new ChassisSpeeds.

constexpr ChassisSpeeds	operator/ (double scalar) const
	Divides the ChassisSpeeds by a scalar and returns the new ChassisSpeeds.

constexpr bool	operator== (const ChassisSpeeds &other) const =default
	Compares the ChassisSpeeds with another ChassisSpeed.

Static Public Member Functions
static constexpr ChassisSpeeds	Discretize (units::meters_per_second_t vx, units::meters_per_second_t vy, units::radians_per_second_t omega, units::second_t dt)
	Discretizes a continuous-time chassis speed.

static constexpr ChassisSpeeds	Discretize (const ChassisSpeeds &continuousSpeeds, units::second_t dt)
	Discretizes a continuous-time chassis speed.

static constexpr ChassisSpeeds	FromFieldRelativeSpeeds (units::meters_per_second_t vx, units::meters_per_second_t vy, units::radians_per_second_t omega, const Rotation2d &robotAngle)
	Converts a user provided field-relative set of speeds into a robot-relative ChassisSpeeds object.

static constexpr ChassisSpeeds	FromFieldRelativeSpeeds (const ChassisSpeeds &fieldRelativeSpeeds, const Rotation2d &robotAngle)
	Converts a user provided field-relative ChassisSpeeds object into a robot-relative ChassisSpeeds object.

static constexpr ChassisSpeeds	FromRobotRelativeSpeeds (units::meters_per_second_t vx, units::meters_per_second_t vy, units::radians_per_second_t omega, const Rotation2d &robotAngle)
	Converts a user provided robot-relative set of speeds into a field-relative ChassisSpeeds object.

static constexpr ChassisSpeeds	FromRobotRelativeSpeeds (const ChassisSpeeds &robotRelativeSpeeds, const Rotation2d &robotAngle)
	Converts a user provided robot-relative ChassisSpeeds object into a field-relative ChassisSpeeds object.

Public Attributes
units::meters_per_second_t	vx = 0_mps
	Velocity along the x-axis.

units::meters_per_second_t	vy = 0_mps
	Velocity along the y-axis.

units::radians_per_second_t	omega = 0_rad_per_s
	Represents the angular velocity of the robot frame.

Detailed Description

Represents the speed of a robot chassis.

Although this struct contains similar members compared to a Twist2d, they do NOT represent the same thing. Whereas a Twist2d represents a change in pose w.r.t to the robot frame of reference, a ChassisSpeeds struct represents a robot's velocity.

A strictly non-holonomic drivetrain, such as a differential drive, should never have a dy component because it can never move sideways. Holonomic drivetrains such as swerve and mecanum will often have all three components.

Member Function Documentation

◆ Discretize() [1/2]

static constexpr ChassisSpeeds frc::ChassisSpeeds::Discretize	(	const ChassisSpeeds &	continuousSpeeds,
		units::second_t	dt )

inlinestaticconstexpr

Discretizes a continuous-time chassis speed.

This function converts a continuous-time chassis speed into a discrete-time one such that when the discrete-time chassis speed is applied for one timestep, the robot moves as if the velocity components are independent (i.e., the robot moves v_x * dt along the x-axis, v_y * dt along the y-axis, and omega * dt around the z-axis).

This is useful for compensating for translational skew when translating and rotating a swerve drivetrain.

Parameters

continuousSpeeds	The continuous speeds.
dt	The duration of the timestep the speeds should be applied for.

Returns: Discretized ChassisSpeeds.

◆ Discretize() [2/2]

static constexpr ChassisSpeeds frc::ChassisSpeeds::Discretize	(	units::meters_per_second_t	vx,
		units::meters_per_second_t	vy,
		units::radians_per_second_t	omega,
		units::second_t	dt )

inlinestaticconstexpr

Discretizes a continuous-time chassis speed.

This function converts a continuous-time chassis speed into a discrete-time one such that when the discrete-time chassis speed is applied for one timestep, the robot moves as if the velocity components are independent (i.e., the robot moves v_x * dt along the x-axis, v_y * dt along the y-axis, and omega * dt around the z-axis).

This is useful for compensating for translational skew when translating and rotating a swerve drivetrain.

Parameters

vx	Forward velocity.
vy	Sideways velocity.
omega	Angular velocity.
dt	The duration of the timestep the speeds should be applied for.

Returns: Discretized ChassisSpeeds.

◆ FromFieldRelativeSpeeds() [1/2]

static constexpr ChassisSpeeds frc::ChassisSpeeds::FromFieldRelativeSpeeds	(	const ChassisSpeeds &	fieldRelativeSpeeds,
		const Rotation2d &	robotAngle )

inlinestaticconstexpr

Converts a user provided field-relative ChassisSpeeds object into a robot-relative ChassisSpeeds object.

Parameters

fieldRelativeSpeeds	The ChassisSpeeds object representing the speeds in the field frame of reference. Positive x is away from your alliance wall. Positive y is to your left when standing behind the alliance wall.
robotAngle	The angle of the robot as measured by a gyroscope. The robot's angle is considered to be zero when it is facing directly away from your alliance station wall. Remember that this should be CCW positive.

Returns: ChassisSpeeds object representing the speeds in the robot's frame of reference.

◆ FromFieldRelativeSpeeds() [2/2]

static constexpr ChassisSpeeds frc::ChassisSpeeds::FromFieldRelativeSpeeds	(	units::meters_per_second_t	vx,
		units::meters_per_second_t	vy,
		units::radians_per_second_t	omega,
		const Rotation2d &	robotAngle )

inlinestaticconstexpr

Converts a user provided field-relative set of speeds into a robot-relative ChassisSpeeds object.

Parameters

vx	The component of speed in the x direction relative to the field. Positive x is away from your alliance wall.
vy	The component of speed in the y direction relative to the field. Positive y is to your left when standing behind the alliance wall.
omega	The angular rate of the robot.
robotAngle	The angle of the robot as measured by a gyroscope. The robot's angle is considered to be zero when it is facing directly away from your alliance station wall. Remember that this should be CCW positive.

Returns: ChassisSpeeds object representing the speeds in the robot's frame of reference.

◆ FromRobotRelativeSpeeds() [1/2]

static constexpr ChassisSpeeds frc::ChassisSpeeds::FromRobotRelativeSpeeds	(	const ChassisSpeeds &	robotRelativeSpeeds,
		const Rotation2d &	robotAngle )

inlinestaticconstexpr

Converts a user provided robot-relative ChassisSpeeds object into a field-relative ChassisSpeeds object.

Parameters

robotRelativeSpeeds	The ChassisSpeeds object representing the speeds in the robot frame of reference. Positive x is the towards robot's front. Positive y is towards the robot's left.
robotAngle	The angle of the robot as measured by a gyroscope. The robot's angle is considered to be zero when it is facing directly away from your alliance station wall. Remember that this should be CCW positive.

Returns: ChassisSpeeds object representing the speeds in the field's frame of reference.

◆ FromRobotRelativeSpeeds() [2/2]

static constexpr ChassisSpeeds frc::ChassisSpeeds::FromRobotRelativeSpeeds	(	units::meters_per_second_t	vx,
		units::meters_per_second_t	vy,
		units::radians_per_second_t	omega,
		const Rotation2d &	robotAngle )

inlinestaticconstexpr

Converts a user provided robot-relative set of speeds into a field-relative ChassisSpeeds object.

Parameters

vx	The component of speed in the x direction relative to the robot. Positive x is towards the robot's front.
vy	The component of speed in the y direction relative to the robot. Positive y is towards the robot's left.
omega	The angular rate of the robot.
robotAngle	The angle of the robot as measured by a gyroscope. The robot's angle is considered to be zero when it is facing directly away from your alliance station wall. Remember that this should be CCW positive.

Returns: ChassisSpeeds object representing the speeds in the field's frame of reference.

◆ operator*()

ChassisSpeeds frc::ChassisSpeeds::operator* ( double scalar ) const

inlineconstexpr

Multiplies the ChassisSpeeds by a scalar and returns the new ChassisSpeeds.

For example, ChassisSpeeds{2.0, 2.5, 1.0} * 2 = ChassisSpeeds{4.0, 5.0, 1.0}

Parameters

scalar The scalar to multiply by.

Returns: The scaled ChassisSpeeds.

◆ operator+()

ChassisSpeeds frc::ChassisSpeeds::operator+ ( const ChassisSpeeds & other ) const

inlineconstexpr

Adds two ChassisSpeeds and returns the sum.

For example, ChassisSpeeds{1.0, 0.5, 1.5} + ChassisSpeeds{2.0, 1.5, 0.5} = ChassisSpeeds{3.0, 2.0, 2.0}

Parameters

other The ChassisSpeeds to add.

Returns: The sum of the ChassisSpeeds.

◆ operator-() [1/2]

ChassisSpeeds frc::ChassisSpeeds::operator- ( ) const

inlineconstexpr

Returns the inverse of the current ChassisSpeeds.

This is equivalent to negating all components of the ChassisSpeeds.

Returns: The inverse of the current ChassisSpeeds.

◆ operator-() [2/2]

ChassisSpeeds frc::ChassisSpeeds::operator- ( const ChassisSpeeds & other ) const

inlineconstexpr

Subtracts the other ChassisSpeeds from the current ChassisSpeeds and returns the difference.

For example, ChassisSpeeds{5.0, 4.0, 2.0} - ChassisSpeeds{1.0, 2.0, 1.0} = ChassisSpeeds{4.0, 2.0, 1.0}

Parameters

other The ChassisSpeeds to subtract.

Returns: The difference between the two ChassisSpeeds.

◆ operator/()

ChassisSpeeds frc::ChassisSpeeds::operator/ ( double scalar ) const

inlineconstexpr

Divides the ChassisSpeeds by a scalar and returns the new ChassisSpeeds.

For example, ChassisSpeeds{2.0, 2.5, 1.0} / 2 = ChassisSpeeds{1.0, 1.25, 0.5}

Parameters

scalar The scalar to divide by.

Returns: The scaled ChassisSpeeds.

◆ operator==()

bool frc::ChassisSpeeds::operator== ( const ChassisSpeeds & other ) const

constexprdefault

Compares the ChassisSpeeds with another ChassisSpeed.

Parameters

other The other ChassisSpeeds.

Returns: The result of the comparison. Is true if they are the same.

◆ ToTwist2d()

Twist2d frc::ChassisSpeeds::ToTwist2d ( units::second_t dt ) const

inlineconstexpr

Creates a Twist2d from ChassisSpeeds.

Parameters

dt	The duration of the timestep.

Returns: Twist2d.

Member Data Documentation

◆ omega

units::radians_per_second_t frc::ChassisSpeeds::omega = 0_rad_per_s

Represents the angular velocity of the robot frame.

(CCW is +)

◆ vx

units::meters_per_second_t frc::ChassisSpeeds::vx = 0_mps

Velocity along the x-axis.

(Fwd is +)

◆ vy

units::meters_per_second_t frc::ChassisSpeeds::vy = 0_mps

Velocity along the y-axis.

(Left is +)

The documentation for this struct was generated from the following file:

frc/kinematics/ChassisSpeeds.h

Public Member Functions

Static Public Member Functions

Public Attributes

Detailed Description

Member Function Documentation

◆ Discretize() [1/2]

◆ Discretize() [2/2]

◆ FromFieldRelativeSpeeds() [1/2]

◆ FromFieldRelativeSpeeds() [2/2]

◆ FromRobotRelativeSpeeds() [1/2]

◆ FromRobotRelativeSpeeds() [2/2]

◆ operator*()

◆ operator+()

◆ operator-() [1/2]

◆ operator-() [2/2]

◆ operator/()

◆ operator==()

◆ ToTwist2d()

Member Data Documentation

◆ omega

◆ vx

◆ vy