1       Definition

A Wheel Command is the directive issued by the Motion Actuation Subsystem to a wheel‑steering actuator (front or rear steering) specifying the intended steering angle, timing, and optionally steering mode and actuator behavior constraints.

CAV steering actuators today support:

  • angle‑based steering,
  • steer‑by‑wire control,
  • multi‑rate closed‑loop correction,
  • safety‑aware motion limits,
  • predictive control for load/road curvature,
  • health‑aware derating.

2       Functional Requirements

A Wheel Command shall:

  1. Identify the Command and Wheel: Provide unique identifiers for tracking and repetition management.
  2. Provide Steering Angle Specification: Include a target wheel angle with safety‑checked limits.
  3. Support Steering Command Profiles (optional): Allow ramp‑up, hold, and ramp‑down phases for smoother actuator control.
  4. Provide Timing Information: Include the intended application time or duration.
  5. Support Safety Constraints: Include optional maximum steering rate, maximum actuator load, etc.
  6. Expose Health‑Aware Control Parameters: Allow derating based on thermal/load/diagnostic inputs.
  7. Support Traceability and Metadata: Include standard AIF metadata and trace information.

3       Syntax

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

4       Semantics

Label Description
Header Wheel Command Header — “CAV‑WHC‑Vx.y” (x.y = version).
WheelCommandID ID of the Wheel Command instance.
WheelID Identifier of the wheel or steering actuator receiving the command.
WheelCommand Set of Wheel Command parameters.
– WheelCommandTime Time interval during which the command shall be applied.
– Angle Target steering angle in degrees.
– SteeringMode Mode of steering actuator (manual, assistive, SBW, etc.).
– SteeringRateLimit Maximum allowed steering rate (deg/s).
– ControlProfile Optional multi‑phase angle control (ramp‑up, hold, ramp‑down).
– SafetyLimits Optional envelope of limits (max torque, max current, mechanical stops).
– HealthAwareness Optional derating/diagnostic hints (thermal, load, calibration).
DataExchangeMetadata Metadata describing context and conditions of data exchange (AIF V3.0).
Trace Trace information enabling reproducibility (AIF V3.0).
DescrMetadata Optional descriptive metadata.