Electronic Design

Looking Over Your Shoulder At The Indy 500

The Indianapolis 500 has come a long way since its start on Memorial Day, May 30, 1911. The inaugural event marked the first time a rear-view mirror was used in a motor race, courtesy of Ray Harroun on the “Marmon Wasp” for Indianapolis automaker Marmon. Harroun also was the only driver in the race who didn’t bring along a mechanic in the passenger seat. Mechanics in those early races checked the oil pressure and also served as the rear-view mirror.

Harroun was considered a hazard because of his newfangled device. These days, multiple rear-view mirrors are standard fare on all cars and trucks. Cars in the Indy 500 are no longer two-seaters, but there is someone looking over the driver’s shoulder—and I’m not talking about the tiny lipstick cameras mounted in the cockpit to give ABC and ESPN viewers a gander at the road ahead.

Rather, I’m referring to the members of the pit crew who are normally huddled around an array of computer displays during the race (see the figure). I recently had a chat with Adam Schaechter, chief engineer for the AJ Foyt Racing Team, about the electronics under the hood of the cars (see “The Indianapolis 500 Electronic Edge”).

One IndyCar is pretty much identical to another by rule. They use the same Honda engine with an electronic control unit (ECU) that isn’t tweaked. The engines are RPM-limited to 10,300 RPM. Even the transmission and gearshift are the same.

On the other hand, the sensors and telemetry can be customized. There are many types of information that every team will want, such as the ECU controller-area network (CAN) traffic, which provides details about engine performance and operation. But that’s not all that the drivers and teams will want to know. Everything from G-force on the car to the pressure of each tire will be of interest.

A standard telemetry system uses 64 channels of data in addition to the gearbox and motor information. Each team is assigned its own frequency, and the information is encrypted. Many of these sensors are standard fare on each car, but these days, it’s easier to include custom sensors.

OFF-THE-SHELF PARTS IN AN INDYCAR
One of the surprising things that Adam told me about was his team’s use of off-the-shelf sensors from outfits like Digi-Key. Development kits make it easy to check out microcontrollers and sensors such as temperature sensors and multiaxis accelerometers. They can be used to detect vibration in components, providing a real-time, car hardware debug environment. Some systems are used during the race. Others are used for design and prior to the race.

The AJ Foyt Racing Team engineers even do their own printed-circuit board (PCB) design from time to time. The team is one of the smaller organizations participating in the Indianapolis 500, so there isn’t a host of electrical engineers, programmers, and other specialists around.

But it does show what is possible with enough interest and drive plus plenty of low-cost chips with ever-improving performance characteristics. The trend toward more intelligent digital sensors allows easier integration.

So is there more? Teams can already add video cameras and even thermal imaging cameras to the mix, although that’s normally done during the design and testing of the cars.

Where are these sensors and what do they do? Well, teams need to maintain their advantages, so I can’t tell you what they won’t tell me. Yet some of the sensors that the AJ Foyt Racing Team uses include microelectromechanical systems (MEMS) accelerometers, and you can image what kinds of things these devices might be used to test.

Part of the challenge with all this information is sensory overload. Lots of information can be gathered but not all of it is useful, especially during the race, when minimal changes can be made. Even the information gathered now isn’t given directly to the driver but rather to the tech team in the pits, who decides what needs to be done. This often involves longer-term planning during a race to determine how the car should be loaded, how lean the engine should run, and so on.

IndyCar drivers still have someone looking out for them, though it is more like an entire crew. This May, maybe you’ll hear, “Drivers, start your telemetry.”

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