ChassisSpeeds

class wpimath.kinematics.ChassisSpeeds(vx: wpimath.units.meters_per_second = 0, vy: wpimath.units.meters_per_second = 0, omega: wpimath.units.radians_per_second = 0)

Bases: pybind11_object

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.

WPIStruct = <capsule object "WPyStruct">
static discretize(*args, **kwargs)

Overloaded function.

  1. discretize(vx: wpimath.units.meters_per_second, vy: wpimath.units.meters_per_second, omega: wpimath.units.radians_per_second, dt: wpimath.units.seconds) -> wpimath.kinematics._kinematics.ChassisSpeeds

Disretizes 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.

  1. discretize(continuousSpeeds: wpimath.kinematics._kinematics.ChassisSpeeds, dt: wpimath.units.seconds) -> wpimath.kinematics._kinematics.ChassisSpeeds

Disretizes 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.

static fromFeet(vx: wpimath.units.feet_per_second = 0, vy: wpimath.units.feet_per_second = 0, omega: wpimath.units.radians_per_second = 0) → wpimath.kinematics._kinematics.ChassisSpeeds
static fromFieldRelativeSpeeds(*args, **kwargs)

Overloaded function.

  1. fromFieldRelativeSpeeds(vx: wpimath.units.meters_per_second, vy: wpimath.units.meters_per_second, omega: wpimath.units.radians_per_second, robotAngle: wpimath.geometry._geometry.Rotation2d) -> wpimath.kinematics._kinematics.ChassisSpeeds

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.

  1. fromFieldRelativeSpeeds(fieldRelativeSpeeds: wpimath.kinematics._kinematics.ChassisSpeeds, robotAngle: wpimath.geometry._geometry.Rotation2d) -> wpimath.kinematics._kinematics.ChassisSpeeds

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.

static fromRobotRelativeSpeeds(*args, **kwargs)

Overloaded function.

  1. fromRobotRelativeSpeeds(vx: wpimath.units.meters_per_second, vy: wpimath.units.meters_per_second, omega: wpimath.units.radians_per_second, robotAngle: wpimath.geometry._geometry.Rotation2d) -> wpimath.kinematics._kinematics.ChassisSpeeds

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.

  1. fromRobotRelativeSpeeds(robotRelativeSpeeds: wpimath.kinematics._kinematics.ChassisSpeeds, robotAngle: wpimath.geometry._geometry.Rotation2d) -> wpimath.kinematics._kinematics.ChassisSpeeds

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.

property omega → wpimath.units.radians_per_second

Represents the angular velocity of the robot frame. (CCW is +)

property omega_dps
property vx → wpimath.units.meters_per_second

Velocity along the x-axis. (Fwd is +)

property vx_fps
property vy → wpimath.units.meters_per_second

Velocity along the y-axis. (Left is +)

property vy_fps