It's All about Data

With the new strategic orientation of Formula Student from a combustion-focused competition to electrically driven and autonomous racing cars, dataloggers are elementary in order to be able to organize the event safely and in accordance with the rules. In close cooperation with partners from the industry, Formula Student Germany provides the teams with the necessary components. This technically oriented article will show how the dataloggers are constructed nd which functions are necessary to ensure data acquisition.

 

Overview

The FS datalogger is a device a that is placed in every autonomous and every electric vehicle taking part in Formula Student competitions. It is used to record the energy consumption of electric vehicles and control data from autonomous vehicles, to ensure the power limits are met, to score energy efficiency and to analyze autonomous system characteristics. The main objective for starting the development of a new datalogger was to address the challenges posed by the increasing count of vehicles participating in Formula Student and the maintenance intensive approach that was chosen previously. In the end, the energy measurement concept is the only thing that remained the same. The datalogger still incorporates a Isabellenhütte IVT-MOD for current and voltage sensing of the tractive system. Further requirements include the ability to power the datalogger via IEEE 802.3af PoE inside its custom-built transport boxes, to ensure rapid setup and minimal work on-site.

Hardware

The core of the datalogger is the Toradex Colibri iMX8QXP. A custom carrier board connecting it to all external interfaces was developed to integrate it into a casing with very similar dimensions to the previous generation. A multi-rail power supply with a wide range of 12V to 60V DC generates the voltages required to power the logger and its components. All the voltage rails are monitored on the M4 coprocessor of the iMX8QXP SOM, to rapidly react to supply spikes. A real time clock, powered by a super capacitor, is used to provide accurate timestamps for the generated logfiles.

Logger Software 

On the iMX8QXP we use a custom Yocto Linux distribution with a mainline Linux kernel. The custom software stack is split into multiple components: The embedded firmware runs on the M4 coprocessor and handles all of the real-time measurements. It communicates with the main processor via OpenAMP. The main processor uses an update module for easy updates of the logging software. This main logging software stores and manages all of the recorded data. Data integrity is ensured via cryptographic signatures. All of the loggers share a backend service running online to exchange configuration, logging and telemetry data. The whole operating system can be updated over-the-air (OTA), with automatic rollbacks and A/B partitions to ensure a safe state. 

Thank you!

We would like to thank all the sponsors and supporters that made it possible to build these Dataloggers, especially Toradex for providing us with the iMX8QXP SOM and Isabellenhütte for providing us with the IVT-MOD sensors.

                         

---