Swerve Drive Odometry
import com.arcrobotics.ftclib.kinematics.wpilibkinematics.SwerveDriveOdometry
A user can use the swerve drive kinematics classes in order to perform odometry. WPILib/FTCLib contains a SwerveDriveOdometry
class that can be used to track the position of a swerve drive robot on the field.
Note: Because this method only uses encoders and a gyro, the estimate of the robot’s position on the field will drift over time, especially as your robot comes into contact with other robots during gameplay. However, odometry is usually very accurate during the autonomous period.
Creating the Odometry Object
0 degrees / radians represents the robot angle when the robot is facing directly toward your opponent’s alliance station. As your robot turns to the left, your gyroscope angle should increase.
Updating the Robot Pose
The update
method of the odometry class updates the robot position on the field. The update method takes in the gyro angle of the robot, along with a series of module states (speeds and angles) in the form of a SwerveModuleState
each. It is important that the order in which you pass the SwerveModuleState
objects is the same as the order in which you created the kinematics object.
This update
method must be called periodically, preferably in the periodic()
method of a Subsystem. The update
method returns the new updated pose of the robot.
Resetting the Robot Pose
The robot pose can be reset via the resetPose
method. This method accepts two arguments – the new field-relative pose and the current gyro angle.
If at any time, you decide to reset your gyroscope, the resetPose
method MUST be called with the new gyro angle.
The implementation of getState()
above is left to the user. The idea is to get the module state (speed and angle) from each module.
In addition, the getPoseMeters()
method can be used to retrieve the current robot pose without an update.
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