NASCAR Vehicle Qualification Testing

Application Summary
NASCAR drivers are legendary for pushing the envelope on racecar design to boost their top speed. Sometimes, in their exuberance to excel, they exceed the track’s rules and regulations concerning body, chassis, or engine modifications. So it’s up to NASCAR officials to monitor and inspect each vehicle to make certain the car qualifies - all the time. But it is a daunting task to outfox these expert mechanics and owners every day. Because of the time and expense required to check every vehicle for relatively small alterations, such as engine modifications and airfoil design, or bolder changes such as implementing traction controls, NASCAR decided to investigate a faster, more automated technique for detecting unacceptable modifications.

Potential Solution
NASCAR contacted a firm that is actively engaged in generating and analyzing ultrasound in non-destructive testing of various types of machinery for industry and the military. Gayle Inc., Nashville, Tenn., had been using ultrasound to evaluate bearings on M1 Abrams tanks and measure noise in several different types of cars in the racing industry. It also characterized the ultrasonic waveforms generated by these vehicles in order to help fine-tune the engines and predict imminent failures. It recorded the wave shapes of known good vehicles and compiled a database to establish an acceptable baseline. Then, when a wave shape recorded on a vehicle being prepared for a race did not correlate well with the baseline, it was analyzed and fine-tuned until it matched the baseline before entering a race.

IOtech’s Solution
James Gayle, the inventor, decided to monitor and analyze the NASCAR vehicles for alterations in much the same way as he did for maximizing their performance. He purchased an IOtech DaqBook^®, connected it to a parabolic microphone, an ultrasound receiver, and a personal computer containing DASYLab^® software, and recorded the vehicles’ sounds as they ran around the track. The wideband microphone picked up a complex signature for every car and fed it to the DaqBook for permanent recording and analysis. They logged in numerous signatures until they were able to decide what the “perfect” signature should look like for an acceptable, track-qualified vehicle.

Gayle and his team studied vehicle signatures that looked different than the standard baseline. As a result, they were able to determine each way in which the drivers or mechanics were altering their cars. NASCAR officials pulled the suspicious cars off the track to see what was changed, and Gayle compiled a database of the unauthorized alterations, which correlated to each unique signature.

“The method used to record the ultrasonic signatures gets astonishing results,” reports Gayle. “The microphone is set up to operate within a 300-ms window and it listens to the cars as they pass at more than 200 mph.” The microphone captures all the information needed to establish a signature for that vehicle. “The ultrasound that is picked up by the microphone is generated solely by the mechanical vibrations of the car. The measurement system can distinguish deviations as small as a change in ignition timing or in the restrictor plate between carburetor and manifold that limits the horsepower — or sounds made from larger changes, such as added traction controls,” says Gayle.

The various technologies available to NASCAR racers today that can make their cars exceptionally different are staggering. “These racers consider it abundantly gratifying to make their cars go faster, and the NASCAR officials in turn look to us to make sure the drivers are not ‘out of the box’ after they tune up,” says Gayle. “If the racers do find some way to be creative, they try to be barely creative, that is, they want to be three inches creative at the finish line, not three or four car lengths.” That makes subtle but significant changes a little more difficult to detect. There are especially specific rules and regulations concerning the mechanical components that the mechanics must obey, and sometimes they try to embellish the vehicle to give them an advantage. But the ultrasound signature system “levels the playing field.”

Conclusion
Gayle Inc. uses an IOtech DaqBook^® to record ultrasounds emitted by NASCAR racing vehicles to establish a typical standard vehicle signature. It uses this signature as a baseline to compare all vehicles in order to detect deviations and ensure that the vehicles conform to NASCAR rules and regulations. Some modifications made to a vehicle can disqualify it from racing. The DaqBook provides both the accuracy and sampling speed Gayle requires. The microphone output frequency is changed, and then fed to a DaqBook, which samples the analog microphone signals at a rate of up to 40 kHz. The DaqBook, in turn, outputs the digital equivalent and sends the data to a computer containing a software program written by Gayle team members to evaluate and analyze all the information.