For MIT Motorsports, in my junior year, I lead a subteam to develop a new data acquisition system (the “DAQ”) for our car.

Our most basic requirements were that the DAQ log all messages sent over the car’s CAN bus and support for sending live telemetry. In addition to that, we wanted the I/O on the DAQ to be flexible–generically compatible with any sensor we might want to buy in the future–and extensible–easily expanded to fit more sensors.

In previous years, our cars had been logging sensor data to an Android phone. This system was could only log messages. The system I conceived split logging and I/O connectivity between two types of devices, with logging and telemetry assigned to a single “data logger” and a set of “sensor nodes” connecting sensors to the CAN bus. The sensor nodes achieve flexibility by using push-in terminal blocks to wire connections from the PCB to the sensors. I/O expansion is as simple as adding more nodes.

I developed the data logger in Altium Designer; the sensor node PCB layout and system software were done by other subteam members. User interaction was my key consideration with the logger. My goal was to make it so that the logger could be “handled without care.” This meant disconnecting power or power brownouts could not be allowed to corrupt data and turn-on had to be near-instant. Also, it had to be possible to download data over USB from the logger while it was installed regardless of whether car itself was on or off.

These requirements ruled-out any devices that had a boot sequence or required “proper” shutdown like the Raspberry Pi or Beaglebone. I ultimately chose to use a Teensy 3.6, with an XBee radio for telemetry. Downloading while powered off is handled by multiplexing the input power between LV system 5V and USB 5V.

One sensor we specifically aimed to support was an inertial measurement unit (IMU). With an IMU and a GPS receiver, we can record the time and location of all logged CAN messages plus the inertial state of the car, enabling “playback” of any drive for analysis.

This projet was fun. Designing for convenience in addition to our already nebuluous requirements added a nice challenge. I’m proud of the results. This system enabled the team to capture and analyze MY18’s stellar track performance at the 2018 FSAE Lincoln competition and provided the data to drive more ambitious design choices for MY19.