Gyro Odometer

Gyro Odometer fuses IMU angular velocity (high-precision rotation measurement) with wheel odometry linear velocity (high-precision translation measurement) into a complete Twist estimate, providing high-frequency (typically 100 Hz) motion input for the EKF.

Fusion Logic

text

twist.linear.x  = v_x (from wheel odometry)
twist.angular.z = w_z (from IMU, bias-corrected)

Covariance matrix:
cov[0][0] = velocity_stddev_xx²
cov[5][5] = angular_velocity_stddev_zz²

ROS 2 Interfaces

Direction	Topic	Message Type	Description
`Sub`	imu	sensor_msgs/Imu	IMU data
`Sub`	vehicle_twist	TwistWithCovarianceStamped	Wheel speed
`Pub`	twist_with_covariance	TwistWithCovarianceStamped	Fused Twist

Tip

Port scenario note: Increase velocity_stddev_xx for tire slippage on wet surfaces; increase angular_velocity_stddev_zz for diesel engine vibration impact on IMU.

EKF Localizer

Pose Initializer