gyro_odometer

Purpose

gyro_odometer is the package to estimate twist by combining imu and vehicle speed.

Inputs / Outputs

Input

Name	Type	Description
vehicle/twist_with_covariance	geometry_msgs::msg::TwistWithCovarianceStamped	twist with covariance from vehicle
imu	sensor_msgs::msg::Imu	imu from sensor

Output

Name	Type	Description
twist_with_covariance	geometry_msgs::msg::TwistWithCovarianceStamped	estimated twist with covariance

Parameters

Name	Type	Description	Default	Range
output_frame	string	output's frame id	base_link	N/A
message_timeout_sec	float	delay tolerance time for message	0.2	N/A

Assumptions / Known limits

• [Assumption] The frame_id of input twist message must be set to base_link.

• [Assumption] The covariance in the input messages must be properly assigned.

• [Assumption] The angular velocity is set to zero if both the longitudinal vehicle velocity and the angular velocity around the yaw axis are sufficiently small. This is for suppression of the IMU angular velocity bias. Without this process, we misestimate the vehicle status when stationary.

• [Limitation] The frequency of the output messages depends on the frequency of the input IMU message.

• [Limitation] We cannot produce reliable values for the lateral and vertical velocities. Therefore we assign large values to the corresponding elements in the output covariance matrix.