Files
allwpilib/robotpyExamples/SwerveBot/drivetrain.py
Gold856 056d7bcbbe [wpimath] Make swerve and differential kinematics functions immutable (#8274)
Originally started with just swerve, but expanded to diff and mecanum
(docs only) for parity across the drivetrains. Return value checks are
applied when possible to make migration easier and to error loudly if
people forget.

---------

Co-authored-by: Joseph Eng <91924258+KangarooKoala@users.noreply.github.com>
2026-04-16 21:23:32 -07:00

99 lines
3.3 KiB
Python

#
# Copyright (c) FIRST and other WPILib contributors.
# Open Source Software; you can modify and/or share it under the terms of
# the WPILib BSD license file in the root directory of this project.
#
import math
import wpilib
import swervemodule
import wpimath
kMaxVelocity = 3.0 # 3 meters per second
kMaxAngularVelocity = math.pi # 1/2 rotation per second
class Drivetrain:
"""
Represents a swerve drive style drivetrain.
"""
def __init__(self) -> None:
self.frontLeftLocation = wpimath.Translation2d(0.381, 0.381)
self.frontRightLocation = wpimath.Translation2d(0.381, -0.381)
self.backLeftLocation = wpimath.Translation2d(-0.381, 0.381)
self.backRightLocation = wpimath.Translation2d(-0.381, -0.381)
self.frontLeft = swervemodule.SwerveModule(1, 2, 0, 1, 2, 3)
self.frontRight = swervemodule.SwerveModule(3, 4, 4, 5, 6, 7)
self.backLeft = swervemodule.SwerveModule(5, 6, 8, 9, 10, 11)
self.backRight = swervemodule.SwerveModule(7, 8, 12, 13, 14, 15)
self.imu = wpilib.OnboardIMU(wpilib.OnboardIMU.MountOrientation.FLAT)
self.kinematics = wpimath.SwerveDrive4Kinematics(
self.frontLeftLocation,
self.frontRightLocation,
self.backLeftLocation,
self.backRightLocation,
)
self.odometry = wpimath.SwerveDrive4Odometry(
self.kinematics,
self.imu.getRotation2d(),
(
self.frontLeft.getPosition(),
self.frontRight.getPosition(),
self.backLeft.getPosition(),
self.backRight.getPosition(),
),
)
self.imu.resetYaw()
def drive(
self,
xVelocity: float,
yVelocity: float,
rot: float,
fieldRelative: bool,
periodSeconds: float,
) -> None:
"""
Method to drive the robot using joystick info.
:param xVelocity: Velocity of the robot in the x direction (forward).
:param yVelocity: Velocity of the robot in the y direction (sideways).
:param rot: Angular rate of the robot.
:param fieldRelative: Whether the provided x and y velocities are relative to the field.
:param periodSeconds: Time
"""
chassisVelocities = wpimath.ChassisVelocities(xVelocity, yVelocity, rot)
if fieldRelative:
chassisVelocities = chassisVelocities.toRobotRelative(
self.imu.getRotation2d()
)
chassisVelocities = chassisVelocities.discretize(periodSeconds)
velocities = wpimath.SwerveDrive4Kinematics.desaturateWheelVelocities(
self.kinematics.toSwerveModuleVelocities(chassisVelocities),
kMaxVelocity,
)
self.frontLeft.setDesiredVelocity(velocities[0])
self.frontRight.setDesiredVelocity(velocities[1])
self.backLeft.setDesiredVelocity(velocities[2])
self.backRight.setDesiredVelocity(velocities[3])
def updateOdometry(self) -> None:
"""Updates the field relative position of the robot."""
self.odometry.update(
self.imu.getRotation2d(),
(
self.frontLeft.getPosition(),
self.frontRight.getPosition(),
self.backLeft.getPosition(),
self.backRight.getPosition(),
),
)