| Requirement Type | Description | Example for AEB |
|---|---|---|
| Performance requirement | Minimum detection performance within ODD | Detect stationary vehicle at >= 40m in daylight, dry road |
| Robustness requirement | Behaviour at ODD boundary | At rain intensity 2-5 mm/h: degraded mode; HMI warning |
| False positive limit | Maximum allowed false activations | < 0.01 false AEB activations per 1000 km driven |
| False negative limit | Maximum allowed missed detections | < 0.001 missed detections per 1000 relevant AEB scenarios |
| Activation timing | Time to activation from detection | AEB activation within 300ms of confirmed detection |
| HMI requirement | Warning to driver for ODD boundary | ODD_EXIT warning displayed within 1s; audible alert |
SOTIF Functional Specification Requirements
Performance Target Definition
YAMLaeb_performance_targets.yaml
# AEB SOTIF performance targets (ISO 21448 Cl. 7)
feature: AEB
detection_performance:
# Within ODD: mandatory performance
vehicle_stationary:
min_detection_range_m: 40
max_false_negative_rate: 0.001 # per 1000 scenarios
conditions: [daylight, dry_road, visibility_100m_plus]
pedestrian_crossing:
min_detection_range_m: 25
max_false_negative_rate: 0.005
max_crossing_speed_mps: 3.0 # within ODD
conditions: [daylight, dry_road]
# ODD boundary: degraded but defined behaviour
light_rain: # 0-2 mm/h
min_detection_range_m: 25 # reduced from 40m
hmi_warning_required: false
medium_rain: # 2-5 mm/h
min_detection_range_m: 15
hmi_warning_required: true
hmi_message: "AEB performance reduced in rain"
heavy_rain: # > 5 mm/h
autonomous_braking: false # outside ODD
hmi_warning_required: true
hmi_message: "AEB deactivated: heavy rain"
false_activation_targets:
max_per_1000km: 0.01 # nuisance braking: customer acceptance limit
note: "False activations are safety-neutral but cause customer dissatisfaction
and may cause driver to disable AEB permanently"Summary
The functional specification for SOTIF differs from traditional safety requirements in one critical way: it must specify behaviour both within the ODD and at the ODD boundary. A traditional functional requirement says "detect stationary vehicle at 40m"; a SOTIF specification adds "and in rain > 5mm/h, activate degraded mode with HMI warning and do not perform autonomous braking". The boundary behaviour specification is what prevents the most common SOTIF failure mode: a system that works perfectly in its ideal conditions but abruptly fails at the ODD edge with no warning or graceful degradation. The false positive limit is equally important -- an AEB that activates unnecessarily on highway is both a safety risk (rear collision from following vehicle) and a customer experience failure that drives users to permanently disable the system.
🔬 Deep Dive — Core Concepts Expanded
This section builds on the foundational concepts covered above with additional technical depth, edge cases, and configuration nuances that separate competent engineers from experts. When working on production ECU projects, the details covered here are the ones most commonly responsible for integration delays and late-phase defects.
Key principles to reinforce:
- Configuration over coding: In AUTOSAR and automotive middleware environments, correctness is largely determined by ARXML configuration, not application code. A correctly implemented algorithm can produce wrong results due to a single misconfigured parameter.
- Traceability as a first-class concern: Every configuration decision should be traceable to a requirement, safety goal, or architecture decision. Undocumented configuration choices are a common source of regression defects when ECUs are updated.
- Cross-module dependencies: In tightly integrated automotive software stacks, changing one module's configuration often requires corresponding updates in dependent modules. Always perform a dependency impact analysis before submitting configuration changes.
🏭 How This Topic Appears in Production Projects
- Project integration phase: The concepts covered in this lesson are most commonly encountered during ECU integration testing — when multiple software components from different teams are combined for the first time. Issues that were invisible in unit tests frequently surface at this stage.
- Supplier/OEM interface: This is a topic that frequently appears in technical discussions between Tier-1 ECU suppliers and OEM system integrators. Engineers who can speak fluently about these details earn credibility and are often brought into critical design review meetings.
- Automotive tool ecosystem: Vector CANoe/CANalyzer, dSPACE tools, and ETAS INCA are the standard tools used to validate and measure the correct behaviour of the systems described in this lesson. Familiarity with these tools alongside the conceptual knowledge dramatically accelerates debugging in real projects.
⚠️ Common Mistakes and How to Avoid Them
- Assuming default configuration is correct: Automotive software tools ship with default configurations that are designed to compile and link, not to meet project-specific requirements. Every configuration parameter needs to be consciously set. 'It compiled' is not the same as 'it is correctly configured'.
- Skipping documentation of configuration rationale: In a 3-year ECU project with team turnover, undocumented configuration choices become tribal knowledge that disappears when engineers leave. Document why a parameter is set to a specific value, not just what it is set to.
- Testing only the happy path: Automotive ECUs must behave correctly under fault conditions, voltage variations, and communication errors. Always test the error handling paths as rigorously as the nominal operation. Many production escapes originate in untested error branches.
- Version mismatches between teams: In a multi-team project, the BSW team, SWC team, and system integration team may use different versions of the same ARXML file. Version management of all ARXML files in a shared repository is mandatory, not optional.
📊 Industry Note
Engineers who master both the theoretical concepts and the practical toolchain skills covered in this course are among the most sought-after professionals in the automotive software industry. The combination of AUTOSAR standards knowledge, safety engineering understanding, and hands-on configuration experience commands premium salaries at OEMs and Tier-1 suppliers globally.