Cinemática de direção diferencial
The DifferentialDriveKinematics
class is a useful tool that converts between a ChassisSpeeds
object and a DifferentialDriveWheelSpeeds
object, which contains velocities for the left and right sides of a differential drive robot.
Construindo o objeto cinemático
The DifferentialDriveKinematics
object accepts one constructor argument, which is the track width of the robot. This represents the distance between the two sets of wheels on a differential drive.
Nota
In Java, the track width must be in meters. In C++, the units library can be used to pass in the track width using any length unit.
Convertendo Speeds Do Chassi Em Speeds Das Rodas
O método toWheelSpeeds(ChassisSpeeds speeds)
(Java) / ToWheelSpeeds(ChassisSpeeds speeds)
(C++) deve ser utilizado para converter o objeto ChassisSpeeds
para o objeto DifferentialDriveWheelSpeeds
. Isso é útil em situações onde você deve converter uma velocity linear («vx») e uma velocity angular («omega») para as velocities esquerda e direita das rodas.
// Creating my kinematics object: track width of 27 inches
DifferentialDriveKinematics kinematics =
new DifferentialDriveKinematics(Units.inchesToMeters(27.0));
// Example chassis speeds: 2 meters per second linear velocity,
// 1 radian per second angular velocity.
var chassisSpeeds = new ChassisSpeeds(2.0, 0, 1.0);
// Convert to wheel speeds
DifferentialDriveWheelSpeeds wheelSpeeds = kinematics.toWheelSpeeds(chassisSpeeds);
// Left velocity
double leftVelocity = wheelSpeeds.leftMetersPerSecond;
// Right velocity
double rightVelocity = wheelSpeeds.rightMetersPerSecond;
// Creating my kinematics object: track width of 27 inches
frc::DifferentialDriveKinematics kinematics{27_in};
// Example chassis speeds: 2 meters per second linear velocity,
// 1 radian per second angular velocity.
frc::ChassisSpeeds chassisSpeeds{2_mps, 0_mps, 1_rad_per_s};
// Convert to wheel speeds. Here, we can use C++17's structured bindings
// feature to automatically split the DifferentialDriveWheelSpeeds
// struct into left and right velocities.
auto [left, right] = kinematics.ToWheelSpeeds(chassisSpeeds);
Convertendo Speeds Das Rodas para Speeds Do Chassi
Também é possível utilizar o objeto cinemático para converter as speeds das rodas individualmente (esquerda e direita) para um único objeto ChassisSpeeds
. O método toChassisSpeeds(DifferentialDriveWheelSpeeds speeds)
(Java) / ToChassisSpeeds(DifferentialDriveWheelSpeeds speeds)
(C++) deve ser utilizado para alcançar isso.
// Creating my kinematics object: track width of 27 inches
DifferentialDriveKinematics kinematics =
new DifferentialDriveKinematics(Units.inchesToMeters(27.0));
// Example differential drive wheel speeds: 2 meters per second
// for the left side, 3 meters per second for the right side.
var wheelSpeeds = new DifferentialDriveWheelSpeeds(2.0, 3.0);
// Convert to chassis speeds.
ChassisSpeeds chassisSpeeds = kinematics.toChassisSpeeds(wheelSpeeds);
// Linear velocity
double linearVelocity = chassisSpeeds.vxMetersPerSecond;
// Angular velocity
double angularVelocity = chassisSpeeds.omegaRadiansPerSecond;
// Creating my kinematics object: track width of 27 inches
frc::DifferentialDriveKinematics kinematics{27_in};
// Example differential drive wheel speeds: 2 meters per second
// for the left side, 3 meters per second for the right side.
frc::DifferentialDriveWheelSpeeds wheelSpeeds{2_mps, 3_mps};
// Convert to chassis speeds. Here we can use C++17's structured bindings
// feature to automatically split the ChassisSpeeds struct into its 3 components.
// Note that because a differential drive is non-holonomic, the vy variable
// will be equal to zero.
auto [linearVelocity, vy, angularVelocity] = kinematics.ToChassisSpeeds(wheelSpeeds);