/vehicle/status/velocity_status#

Specifications#

Description#

Get the current velocity status of the vehicle.

The rate of 10 Hz in the table is a design value. The autoware_component_interface_specs package does not define a rate. Known publishers send the status faster: autoware_simple_planning_simulator publishes it at 40 Hz (timer_sampling_time_ms: 25), and pacmod_interface publishes it once for each set of PACMod reports. The consumers need a steady rate. For example, autoware_gyro_odometer gets this velocity through autoware_vehicle_velocity_converter. It stops its output when the latest vehicle twist is more than message_timeout_sec (0.2 s by default) older than the latest IMU message.

Message#

See the message definition for details.

Errors#

Unknown status: If the vehicle interface cannot get the status due to connection loss, etc., the status is stopped and a diagnostic error is reported.

Hardware Fault: If the vehicle platform reports a sensor fault, a diagnostic error is reported.

Support#

This interface is required.

Limitations#

Wheel speed: The vehicle interface often computes the longitudinal velocity from the wheel speeds. For example, pacmod_interface uses the mean speed of the rear wheels and the tire radius, and it takes the sign from the gear report. Wheel slip and an incorrect tire radius cause errors. The speed_scale_factor parameter of autoware_vehicle_velocity_converter can correct a scale error.

Heading rate: The vehicle interface can compute the heading rate instead of measuring it. For example, pacmod_interface computes it from the velocity, the steering angle, and the wheelbase with a kinematic model. autoware_gyro_odometer uses the angular velocity of the IMU instead.

Lateral velocity: Some vehicle interfaces do not set the lateral velocity. For example, pacmod_interface does not set the lateral_velocity field, so its value is always 0.

Use cases#

• Control the vehicle for autonomous driving.
• Display current velocity status to the operator.

Requirement#

• Support getting the current velocity status of the vehicle.
• Report the error as diagnostics if the status cannot be received or an unknown status is received.

Design#

Coordinate system & sign convention: The interface follows the standard vehicle coordinate system (ISO 8855 / ROS REP-103).

• Longitudinal velocity: Positive (+) indicates forward motion. Negative (-) indicates backward motion.
• Lateral velocity: Positive (+) indicates motion to the left. Negative (-) indicates motion to the right.
• Heading rate: Positive (+) indicates counter-clockwise rotation (left turn).

History#