1      Black Box Product Function

1.1      Product Feature

The black box is used to record the operating status of a vehicle during its operation. In past automotive accidents, severe vehicle damage often made it impossible to obtain the vehicle's status at the time of the accident, which could not guarantee the rights and interests of the driver and could not determine if there were any issues with the vehicle. Therefore, the data stored in the black box can effectively solve the above problems.

Figure 4-1 Architectural Principle Diagram

1.2       Implementation Plan

The DFlash space supported by TC277 is 384KB. Due to the characteristic of DFlash that data is not lost when power is lost, it is used to store fault data.

An Error Manager module function for fault management is added at the CDD layer. When a fault occurs at the upper SWC layer, the Error Manager module can be called to pass fault-related information, which is then written into the DFlash for storage by the Error Manager module, as shown in Figure 4-2.

The SWC layer can also call the Error Manager's clear function to remove data stored in DFlash that is no longer needed, ensuring there is enough space to store subsequent new fault information.

Fault information can be obtained through the read interface of the Error Manager module and reported to the upper computer tool, facilitating test personnel in obtaining fault information for troubleshooting vehicle issues.

Figure 4-2 Fault Storage Framework

1.3      Fault Storage Process

Figure 4-3 Fault Storage Process

After faults are reported in the application layer's periodic tasks, the fault management module (Error Manager) will proceed with the following steps:

1.    Check if the fault to be recorded meets the conditions.

2.    Lock the current DFlash area to prevent other tasks from calling the write function again.

3.    Write the fault information into the DFlash area.

4.    Check if the written result is correct.

5.    The Error Manager module completes the write process.

1.4      Fault Clearing Process

Figure 4-4 Fault Clearing Process

After the application layer's periodic task issues a request to clear a fault, the fault management module (Error Manager) will proceed with the following steps in sequence:

1.    Check if the fault to be cleared meets the conditions.

2.    Lock the DFlash area that is currently being operated on, preventing other tasks from calling the clear function.

3.    Clear the stored data.

4.    Check if the cleared result is correct.

5.    The Error Manager module completes the data clearing.

1.5      Fault Reading Process

FIGURE 4-5 FAULT READING PROCESS

When the application layer's periodic task needs to obtain fault information, the fault management module (Error Manager) will proceed with the following steps in sequence:

1.    The Error Manager module detects the fault status.

2.    Read the data stored in the DFlash.

3.    After reading is completed, check the read status and report the read data.

2      ZC Xuanwu Product Function

2.1      Product Feature

To facilitate the data playback of the black box, ZC has launched the XuanWu diagnostic testing tool, which can read the data stored in the black box, allowing technicians to more easily access fault data.

ZC Xuanwu has the following features:

Ø  Easy to Operate

n  Graphical interface for convenient configuration

n  Automatically parses black box data such as DID and DTC and generates Excel files

n  Supports diagnostic configurations and standards for different OEMs

Ø  Flexible to Use

n  Supports CAN, CAN FD, and Kline protocols

n  Supports standards such as ISO 14229, ISO 15765, and ISO 14230

n  Supports various hardware interfaces

Ø  Customization Services Available

2.2      Playback Function

The Xuanwu upper computer can obtain fault information from the black box's storage space through diagnostic services, complete the parsing of fault information, and display the parsed fault data signals in a graphical interface.

Figure 5-1 Data Playback

The Xuanwu upper computer can plot waveform charts of the data such as U-phase current, V-phase current, and W-phase current at the time of fault occurrence over time.

FIGURE 5-2 DATA PLAYBACK GRAPHICAL USER INTERFACE

2.3      Test Cases

Xuanwu supports the development of test cases based on Python and provides a Python API interface for diagnostic services, facilitating secondary development by users.

Figure 5-3 PYTHON API Illustration

Based on the requirements of the black box playback function, test engineers have written a complete set of test cases, including data storage, erasure, repeated read/write, stress testing, etc., which can be automated through the Xuanwu tool.

Figure 5-4 Custom Test Program 

2.4      Test Report

In response to test results, the Xuanwu tool can automatically generate test reports.

Figure 5-5 Test Report

The automotive black box, also known as the Event Data Recorder (EDR), is one of the important functions of a vehicle controller. This system is primarily responsible for recording driving data during vehicle accidents, including data from three stages: before, during, and after the collision, such as speed, ABS status, steering wheel angle, airbag status, and vehicle braking status.

The black box has anti-tampering and readable/writeable characteristics, similar to the functionality of the black box on an airplane. The black box continuously monitors the vehicle's operational data through CAN. When the vehicle's speed change over a certain period reaches a preset threshold (indicating an accident), the black box stores information about the vehicle's condition from several seconds before to after the collision. Technicians can use the data stored in the black box to analyze any faults in the vehicle or to determine the cause of the accident.

This document describes the black box designed based on the Infineon TC277 platform. It currently supports the black box specifications of multiple vehicle manufacturers. It supports multiple data storage, data writing, reading, and clearing, and supports various reading methods such as reading based on UDS diagnostic services from the upper computer, reading based on calibrated CAN, and reading via the JTAG interface.

The automotive black box plays a significant role in automotive fault diagnosis and accident investigation, with the following main applications:

ØTraffic Accident Reconstruction. By acquiring pre-collision and post-collision data from the black box and combining it with computer simulation technology to recreate the accident scene, it helps to eliminate subjective factors and improve the accuracy of accident reconstruction in both numerical reconstruction and collision morphology reconstruction.

ØTraffic Accident Investigation and Forensic Appraisal: The appraisal of vehicle speeds and driver behavior in atypical collision accidents has always been a challenge in traffic accident forensics. Data from the black box helps avoid complex calculation processes and significantly reduces computational errors.

ØVehicle Safety Improvement: The black box records a large amount of data related to vehicle safety systems, especially information related to collisions such as speed, speed changes, airbag deployment, occupant seat belt usage, and driver emergency response behaviors. This data is helpful for assessing the effectiveness of safety systems in actual accidents and aids automakers and safety suppliers in iterating and upgrading vehicle safety performance based on real-world conditions.

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