Adam Larnach is a data and information services consultant for the industrial, defense and motorsport industries. He is currently serving as the "DAG" (Data Acquisition Guy) for Autocon Motorsports and its 2009 American Le Mans Series program with an AER-powered Lola B06/10.
In Part I of “Autocon Analysis” I covered the basic “nodes” or sensors of the car’s network. All of these sensors tie into the CAN bus which connects several devices in the same way a peer-to-peer computer network operates.
Let’s start with the data-logger. What you essentially have are numerous devices that send various electrical signals to the logger, whether it be voltage, amperage, resistance, etc. The logger has a multiple configuration files that contain a calibration table (similar to a line graph) for each sensor. Some use 2D calibration tables, others use 3D calibration tables. For example, a linear damper sensor would be a 2D table calibration. At 0.5v you would have 0mm of damper travel, and at 5v you would have 70mm of damper travel. Other sensors require parabolic calibrations, or three planes of calibration (3D). The sensor manufacturers typically set the calibration type and values, although some sensors are calibrated to a team’s specification (usually damper and ride height sensors). The data logger can also be configured to receive data from other devices such as an ECU, gearshift controller, radio, etc.
When configuring the logger, you also need to set the rate data is logged or the resolution at which you record the data. During testing, practices and qualifying you can generally get away with running all logging rates at their maximum. With Autocon’s current logger system, it’s necessary to scale back logging rates in order to record a full race. Last year at Le Mans I had the “luxury” of having a high capacity logger that had enough storage space to log the entire 24-hour race at maximum rates…basically a full DVD worth of data. So there are many options that you can explore when setting up logging system.
During practice, testing, and qualifying I will download data from the car during every pit stop and do a quick check before the car leaves pit lane. While the car is on the track I will periodically analyze the data while watching the telemetry feeds, which I’ll analyze on the fly.
To understand how the telemetry system works, think of it as just a one-way wireless connection. The logger will send a stream of data through the car’s radio modem; an antenna mounted upon a 30-40’ mast in pit lane receives this signal. This antenna connects to the receiving radio modem, which is connected to a server’s serial port. The server acts as a host to all of the other devices on a secured wireless pit lane network. The server also has the MGB router feeds that host various applications such as IMSA Timing & Scoring, IMSA’s instant messaging system, and various other IMSA applications. Really at the end of the day it’s a basic computer network similar to what you would see in a small office.
Watching and analyzing the telemetry on Autocon’s Lola is a full time job for three people, so we generally have 4-5 sets of eyes on various pages of data looking for specific information. AER will watch a page with engine data - the Engineer and DAG will watch an “overview” page while recording lap times, fuel economy and making the necessary strategy adjustments. Occasionally two of the mechanics will watch the chassis data pages or just to assist in keeping an eye on things. There are approximately 19 telemetry pages that cover everything from damper movement to tire pressures in great detail; this allows for a more detailed look at any specific issue should we see an issue on the main “overview” telemetry page.
Obviously temperatures and pressures are always a concern, so generally you will have several readouts of critical systems (oil, water, gearbox, fuel, etc.) and set warnings when they go above or below specified thresholds. Other issues aren’t always apparent and can only be seen when looking at a much larger field of data. For instance, in the more detailed telemetry pages you can have data from 30 minutes prior still on the screen, and watching a graph (oil pressure for instance) you can see a trend line as it going downward indicating a possible engine issue. Think of it as watching a signal of a heartbeat. Doctors know what anomalies to look for and what a healthy heart’s signal will look like… basically it’s the same idea.
This applies to analyzing the logged data too, except you can get into more detailed analysis using scatter plots, histograms, conditional track maps, etc. After every session the Engineer, DAG, and drivers will go over the data to not only look for areas of improvement, but to reveal any issues with the car. It is just as crucial to maintain the car’s electrics as the mechanical components. Something as simple as a damaged wheelspeed sensor will cause you to lose traction control – it’s the small things that can start to add up and end your day in a hurry.
With that in mind, the ‘nut’ behind the wheel also plays an important role. Comparing hot laps between drivers can show areas where time is being gained and lost. You can also analyze the driver inputs and determine whether the car can be pushed further or it’s being abused (such as dragging the brakes or clutch while on the throttle). It’s also important to note that different driving styles lead to different conditions and bringing the more abusive driving habits under control is crucial to the durability and longevity of the car’s wear components, let alone reducing lap times. Last year at Le Mans I lost one lap per tank with one driver (only by 2-3 liters) because he was hard on the car. Over a several hours this added up to a huge loss of time in the pits, which proves why it’s so important to harmonize driving styles.
Autocon has taken a huge step in the right direction for the 2009 season by improving the tools at its disposal. By running a comprehensive data logging system, and an exhaustive maintenance program headed by Team Manager Evan Chance (also pulling double duty as Car Chief), has allowed the Autocon team to produce a consistent and reliable chassis platform for this season. With nearly one year of ownership under the belt, the Autocon team is looking forward to running a solid and consistent race at Petit Le Mans against some of the greatest drivers and cars this sport has ever seen. See you all in Atlanta!
