Definition
Functional Requirements
Syntax
Semantics
Conformance
Performance
1 Definition
Brake States define the set of operational conditions that a Brake may report to the Motion Actuation Subsystem (MAS). They describe real, physical brake behaviour that the MAS needs to interpret braking performance, diagnose issues, and ensure safe autonomous‑vehicle operation.
2 Functional Requirements
Brake States shall enable the CAV’s Motion Actuation Subsystem (MAS) to:
- Interpret the brake’s current physical behaviour — including braking, holding, releasing, and wheel‑stop conditions.
- Monitor advanced brake control behaviours — such as ABS, traction control, and regenerative braking.
- Detect thermal, wear‑related, and functional degradation — supporting safe decision‑making.
- Identify emergency‑related behaviour — e.g., emergency braking triggered by AEB logic.
- Detect fault states — to trigger fallback behaviour and safe stops.
- Remain compatible with the minimal V1.0 state set — Normal and WheelStopped — for backward compatibility.
3 Syntax
https://schemas.mpai.community/CAV2/V2.0/data/BrakeStates.json
4 Semantics
Table 1 specifies the semantics of the Brake States Data Type.
| Value |
|---|
| Normal |
| WheelStopped |
| Braking |
| Released |
| Hold |
| EmergencyBraking |
| ABSActive |
| TractionControlActive |
| RegenerativeBraking |
| Overheated |
| Degraded |
| Fault |
| Unavailable |
| PreCharge |
| PressureBuildUp |
| PressureDecay |
| HydraulicSaturation |
| LowBrakeFluid |
| PadWearLimit |
| CaliperStuck |
| LinePressureAnomaly |
| ElectronicActuatorFault |
| SelfTest |
| ServiceMode |
5 Conformance Testing
Data conform to the Brake States Data Type when they validate against its schema. If the schema references other schemas, data referencing a secondary schema shall also validate against that schema, if present, and conform with the Qualifier, if present.
