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SAE J1698-2023: Event Data Recorder Standardization for Light Duty Vehicles
SAE J1698-2023 provides common definitions and operational elements for Event Data Recorders (EDRs) in light duty vehicles. This recommended practice, part of the J1698 series, is essential for engineers working on vehicle crash data analysis, occupant protection, and compliance with FMVSS Part 563. This article covers the scope, key definitions, retrieval protocols, and engineering insights.
Scope and Series Overview
The J1698 series includes three parts: output data definitions, retrieval tool protocol, and compliance assessment. The 2023 revision updates terminology based on SAE EDR Committee discussions.
The standard defines data capture, recording, storage in non-volatile memory, and mechanisms to prevent tampering and ensure data integrity.
Key Definitions and Engineering Design Insights
EDR data is distinct from diagnostic freeze-frame or telematics data. The retrieval tool must authenticate and encrypt extracted binary data.
🛠️ Design Insight: EDR records for locked events are not overwritten by subsequent events, ensuring data preservation for analysis. The EDR function monitors time-series data prior to and during defined events, storing records in non-volatile memory.
The vehicle coordinate system specifies acceleration components: longitudinal (X), lateral (Y), and normal (Z). Definitions for crash pulse and delta-V are crucial for event analysis.
The following table illustrates the seating position convention used in EDR data, based on NHTSA’s FARS system.
| Signal Value | Seating Position |
|---|---|
| 11 | Front Seat – Left Side |
| 12 | Front Seat – Middle |
| 13 | Front Seat – Right Side |
| 21 | Second Seat – Left Side |
| 22 | Second Seat – Middle |
| 23 | Second Seat – Right Side |
| 31 | Third Seat – Left Side |
| 32 | Third Seat – Middle |
| 33 | Third Seat – Right Side |
Common Questions and Answers
What are the specific trigger criteria that cause an EDR to record an event?
The trigger criteria are defined by the manufacturer and are related to crash or crash-like events that meet specified conditions, such as a change in velocity beyond a threshold. The standard references the vehicle’s occupant protection control algorithm. The retrieval tool protocol and compliance assessment documents provide further details.
How is delta-V calculated and what is its accuracy?
Delta-V is the cumulative change in vehicle velocity as recorded by the EDR, derived from the acceleration-time history (crash pulse). Accuracy depends on sensor calibration and algorithm. The compliance assessment (J1698-3) defines procedures to validate reporting requirements per Part 563.
What authentication and encryption mechanisms are required?
The retrieval tool must authenticate and encrypt the imaged binary data to ensure it is genuine and unaltered. The standard specifies that the tool must authenticate saved un-translated files and translate them into a human-readable report.
How does the EDR interface with the vehicle for data retrieval?
The retrieval tool connects to the vehicle’s SAE J1962 diagnostic connector. The protocol for imaging the EDR record is defined in J1698-2, utilizing existing industry standards.
⚠️ Attention: A common mistake is confusing EDR time-series data with diagnostic freeze-frame data. Engineers must ensure that implementation of trigger conditions is correct to avoid missing events or recording non-events.
For full details, refer to the SAE J1698 series documents and the NHTSA Part 563 regulation. 🔍
