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Definition
Functional Requirements
Syntax
Semantics
Conformance Testing
Performance Assessment

1      Definition

A Motor Command is a directive issued by the Motion Actuation Subsystem to a traction or steering motor of a Connected Autonomous Vehicle (CAV). It defines what the motor shall achieve – typically expressed as target velocity, torque, or position – together with when and how to apply the command.

MPAI‑CAV deployments increasingly rely on motors requiring richer descriptions:

  • Precise torque envelopes.
  • State‑dependent limits.
  • Health and temperature awareness.
  • Actuator‑side feedback expectations.
  • Safety overrides.

2      Functional Requirements

A Motor Command shall:

  1. Identify the Command and Motor – Include unique identifiers for the command lifecycle and the target Motor.
  2. Support Multi‑Mode Actuation – Express control in velocity, torque, acceleration, or position, depending on motor type.
  3. Provide Timing Information – Include the intended moment of application, duration, or scheduling within the control cycle.
  4. Support Safety‑Aware Execution – Incorporate optional limits and safety thresholds (current, temperature, torque caps).
  5. Allow Explicit Control Profiles – Enable multi‑phase envelopes (e.g., ramp‑up, hold, ramp‑down).
  6. Include Optional Predictive Control Parameters – Such as feed‑forward torque correction or expected load compensation.
  7. Support Data Exchange and Traceability – Provide standard MPAI‑PTF Data Exchange Metadata for logging and system verification.
  8. Be Forward‑Compatible – Allow future additions without breaking existing deployments via optional fields.

3      Syntax

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

4      Semantics

Table 1 – Semantics of the Motor Command Data Type

Label
Description
Header Motor Command Header – Standard “CAV‑MRC‑Vx.y”.
MInstanceID Identifier of the M-Instance (Virtual Space) associated with this Motor Command.
UEnvironmentID Identifier of the U-Environment (Real Space) associated with this Motor Command.
MotorCommandID Unique identifier of this Motor Command instance.
MotorCommandTime Time this Motor Command was produced.
MotorCommandSpaceTime Space/Time where/when this Motor Command applies.
MotorID Identifier of the motor to which this command is addressed.
MotorCommand Set of Motor Command parameters.
    – ControlMode Specifies which control modality is active: “velocity”, “torque”, “position”, or “acceleration”.
    – MotorCommandTime Time interval during which the command shall be applied.
    – TargetVelocity Target motor output velocity (m/s). Valid when ControlMode = velocity.
    – TargetTorque Target motor torque (N·m). Valid when ControlMode = torque.
    – TargetPosition Target shaft or steering position (radians or degrees). Valid when ControlMode = position.
    – TargetAcceleration Target acceleration (m/s²). Valid when ControlMode = acceleration.
    – ControlProfile[] Optional multi-phase actuation profile (ramp-up, hold, ramp-down), each with duration and optional target values.
        – Phase Phase of the actuation profile: “ramp-up”, “hold”, or “ramp-down”.
        – Duration Duration of this phase in seconds.
        – Velocity Target velocity for this phase (m/s).
        – Torque Target torque for this phase (N·m).
        – Acceleration Target acceleration for this phase (m/s²).
    – SafetyLimits Optional safety envelope including maximum allowable current, temperature, and torque.
        – MaxCurrent Maximum allowable motor current (A).
        – MaxTemperature Maximum allowable motor temperature (°C).
        – MaxTorque Maximum allowable torque (N·m).
    – HealthAwareness Optional health-aware parameters such as thermal derating mode and expected load.
        – ThermalDerating Indicates whether thermal derating mode is active.
        – ExpectedLoad Estimated load to be compensated (N·m or kg).
        – MotorStateHint Optional hint from the motor-health subsystem.
DataXMData MPAI-PTF Data Exchange Metadata providing provenance, authorisation, legal, security, and confidence information associated with this Motor Command in a trusted data exchange context.
DescrMetadata Human-readable descriptive metadata of the Motor Command (plain text, max 2048 characters).

5      Conformance Testing

A Data instance conforms with Motor Command (CAV‑MRC) if:

  1. The Data validates against the Motor Command’s JSON Schema.
  2. All Data in the Motor Command’s JSON Schema:
    1. Have the specified type.
    2. Validate against their JSON Schemas.
    3. Conform with their Data Qualifiers.

6      Performance Assessment

Not part of this specification.

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