1   Definition

A Wheel Response is the signal produced by a steering wheel actuator in a Connected Autonomous Vehicle (CAV) in response to a Wheel Command.
It reports the actual steering angle, operational wheel state, timing, and optional health and anomaly indicators for closed‑loop steering control within the Motion Actuation Subsystem.

Realistic steer‑by‑wire systems today provide:

  • measured steering angle and rate,
  • actuator load/torque,
  • mechanical stop warnings,
  • state information (active, idle, fault, stuck, calibrating),
  • anomaly or diagnostics reports,
  • traceability metadata.

2   Functional Requirements

A Wheel Response shall:

  1. Identify the Response and Wheel: Include unique identifiers (WheelID, WheelResponseID).
  2. Report Steering State and Measured Values: Provide actual wheel angle, steering rate, and state (normal, holding, stuck, faulted, etc.).
  3. Include Timing Information: Indicate the time at which the measurement was taken.
  4. Include Health and Diagnostic Indicators: These include thermal conditions, actuator load, sensor health, and mechanical-stop proximity.
  5. Support Anomaly Reporting: Provide structured flags for unexpected actuator behavior.
  6. Support Traceability: Include trace metadata in compliance with AIF V3.0.

3   Syntax

https://schemas.mpai.community/CAV2/V1.1/data/WheelResponse.json

4   Semantics

Label Description
Header Wheel Response Header — “CAV‑WHR‑Vx.y” (x.y = version).
WheelResponseID ID of the Wheel Response instance.
WheelID Identifier of the wheel generating the response.
WheelResponse Set of Wheel Response parameters.
– WheelResponseTime Timestamp at which the response was measured.
– WheelState Operational state of the wheel actuator (normal, hold, stuck, fault, unavailable, etc.).
– WheelAngle Measured steering angle (degrees).
– SteeringRate Measured angular velocity (degrees per second).
– ActuatorLoad Estimated actuator load or steering torque (Nm).
– Temperature Actuator or motor temperature (°C).
– AnomalyFlags Boolean indicators of issues (sensor fault, mechanical stop, overload, unexpected behavior).
DataExchangeMetadata Metadata describing context of the data (AIF V3.0).
Trace Trace data required for reproducibility (AIF V3.0).
DescrMetadata Optional descriptive metadata.