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Understanding SAE J1698-1A: Pedestrian Protection EDR Output Data Definitions
Introduction and Purpose
SAE J1698-1A, titled “Pedestrian Protection EDR Output Data Definition,” is an appendix to the broader SAE J1698-1 standard. Established in 2016 and stabilized in 2021, this document defines the Event Data Recorder (EDR) output data parameters and definitions specifically for pedestrian protection systems in light duty passenger vehicles. Its primary purpose is to establish parameters useful for analyzing pedestrian protection system operation or reconstructing pedestrian crashes. The standard has been stabilized and its content has been incorporated into Appendix A of SAE J1698-1, but it remains a valuable reference for understanding the data elements involved.
Key Definitions and Data Element Classifications
The standard defines several critical concepts for pedestrian protection EDRs, including the definition of Time Zero, clipping flags, and active vs. passive systems. Time Zero marks the beginning of a pedestrian protection event and is defined based on the control algorithm type: either when a wake-up algorithm is activated or when a continuously running algorithm determines specific criteria are met. This is crucial for aligning data from multiple recording devices.
Data elements in the standard are categorized into three classifications based on their importance for crash reconstruction and vehicle safety system analysis:
| Classification | Description |
|---|---|
| Classification I | Data elements that are required for all EDRs. These include high-level vehicle information such as vehicle speed, brake status, and ignition cycle. |
| Classification II | Elements that are required only if the vehicle is equipped with a pedestrian protection system. Examples include indicator status and deployment criteria met. |
| Classification III | Elements that are required only if the vehicle system records the specific data. These often involve sensor data specific to pedestrian protection. |
Additionally, data elements are typed as either time series (recorded at successive intervals) or static (constant for the event). The standard also defines how to handle data not available, invalid data, and the status of each element.
Engineering and Design Insights
🛠️ The stabilization notice indicates that this document is no longer intended for new designs. The information and data elements have been incorporated into Appendix A of SAE J1698-1. Engineers should reference the main standard for current applications. However, the definitions and classifications in J1698-1A provide foundational knowledge for understanding pedestrian protection EDR data.
⚠️ Stabilization Notice: The SAE Event Data Recorder Committee has declared J1698-1A stabilized. Users are responsible for verifying references and continued suitability. Newer technology may exist beyond this specification.
A common mistake is to assume this standard is still actively updated. It is not; it has been stabilized and superseded in effect by the incorporation into J1698-1. Another key insight is the careful definition of Time Zero, which is specific to pedestrian protection and differs from general EDR definitions. This ensures consistency when analyzing timestamps from multiple event data recorders.
The standard covers specific pedestrian protection parameters such as deployment criteria met, non-deployment event status, and recording complete flags. For sensor data, the standard provides guidelines on how to record and report data, including clipping indicators.
🔍 Engineering Design Insight: When designing new pedestrian protection EDR systems, it is recommended to follow the latest version of SAE J1698-1 directly, rather than the stabilized appendix. The data elements and definitions from J1698-1A have been incorporated, ensuring consistency with the main standard.
Frequently Asked Questions
1. What is the primary purpose of SAE J1698-1A?
SAE J1698-1A establishes pedestrian protection parameters and definitions for EDRs in light duty vehicles, useful for analyzing system operation and reconstructing pedestrian crashes.
2. How is Time Zero defined for a pedestrian protection event?
Time Zero is defined as either the time a wake-up pedestrian protection control algorithm is activated, or the time a continuously running algorithm determines that specific criteria for pedestrian protection have been met. It is not necessarily the moment of physical contact.
3. Is SAE J1698-1A still active for new designs?
No. The standard has been stabilized and is no longer intended for new designs. Its content has been incorporated into Appendix A of SAE J1698-1, which should be used for current applications.
4. What are the three classifications of data elements in the standard?
Classification I elements are required for all EDRs. Classification II elements are required only if the vehicle has a pedestrian protection system. Classification III elements are required only if the specific data is recorded by the vehicle system.
