Smart helmets monitor football injuries

This year, however, Virginia Tech University (Blacksburg, Va.) is acting on its concerns. Working with electronics suppliers and engineering professors at the school, the university's football team has outfitted its helmets with sensors, microprocessors and RF transceiver chips that can help tell how hard the players are getting hit on the head.

Ultimately, the engineers behind the project hope that the technology will pave the way for development of systems that could provide earlier recognition of dangerous head injuries in college, high school, and even in youth football programs.

"The big problem right now is that when a player gets a concussion and doesn't realize it, he's susceptible to sustaining another impact that could be fairly dangerous," noted Jeffrey Chu, research engineer for Simbex LLC (Lebanon, N.H.), a maker of the biomechanical feedback system used in Virginia Tech's helmets. "Eventually, a device like this could alert the medical staff, parents, or coaches that the player has taken a hard hit."

Smart helmets

Virginia Tech, which plays in the Insight Bowl next Friday (December 26th) in Phoenix, has been using the technology since the beginning of this football season. Its effort, supported by funding from the National Institutes of Health, has involved installing a biofeedback system in eight helmets, used by 38 different players. Over the course of the football season, the university has collected information on more than 3,000 high-impact collisions from those 38 players, enabling researchers to gain a better understanding of head injuries.

"We're looking at how accelerations predict head injuries," said Stefan Duma, director, Center for Injury Biomechanics, Department of Mechanical Engineering at Virginia Tech University. "Concussion is an internal tissue failure in the brain, and it's caused by acceleration."

The device for monitoring injuries, known as the HIT (Head Impact Telemetry) System, is installed in football helmets in a way that doesn't distract players. An "electronic brick" inside the helmet consists of six linear accelerometers from Analog Devices, Inc. (Norwood, Mass.) and two tiny printed circuit boards, one containing a microcontroller and another incorporating an RF transceiver.

"When a player sustains a head impact, it triggers all six accelerometers, and the system saves data locally in the helmet," Chu said. "If RF communication is available, it then downloads the data to a receiver and computer on the sidelines."

The system accomplishes that by employing accelerometers with spring-loaded buttons that are always in contact with the player's head. When the player's head receives a hit that exceeds a prescribed impact of 10 G's, the buttons are depressed and the accelerometers send the "hit data" through a set of wires connected to a 20-pin micro-miniature IDC (insulation displacement connector) from Samtec, Inc. (New Albany, Ind.) on the processor board. The processor board, measuring a scant 1 X 1.3 inches, incorporates a Hitachi H8 microcontroller, a 10-bit A/D converter, 16K of on-chip RAM, and 128K of flash memory. Developed for the application by engineers at Microprocessor Designs, Inc. (Shelburne, Vt.), the board receives the accelerometer signals, filters them, and then sends them to the Hitachi microcontroller.

The microcontroller then communicates in serial fashion with a separate board containing an RF transceiver from Lab Partners Associates (South Burlington, Vt.). Operating in the 902-928 MHz frequency range, the transceiver sends the hit data from the helmet to a receiver located on the sidelines, which shares the data with a laptop computer. The laptop, incorporating a dynamic-linked library (DLL) from Microprocessor Designs and higher-level application software written by Simbex, derives information on the magnitude, duration, and location of the impact. It then displays that information on the laptop screen, complete with three-dimensional graphics of the human head and indicators to show where the player was hit.

Engineers from Microprocessor Designs said that one of their toughest challenges was incorporating the HIT System into a standard helmet. "Simbex wanted the system be retrofitted into an existing helmet and they didn't want the user to notice any hardware or heavy batteries," said Jeff Finkelstein, president of Microprocessor Designs, which performed the hardware and firmware design.

To power the system discreetly, engineers selected two off-the-shelf AAA nickel-metal hydride batteries. "The players needed to be able to take the helmet from the locker room to practice, and then to a game, so they needed to get eight hours of operation from a single charge," Finkelstein said.

Hit-O-Meter

Using the smart helmets, researchers at Virginia Tech say they want to gain a wealth of knowledge about the causes of head injuries. By looking at accelerations of the head, they say they can make better assessments about concussions and similar injuries.

"Your brain is a soft tissue and when you accelerate it, you can exceed its ability to move that fast," said Duma of Virginia Tech. "That's when you damage the tissue."

In doing the study, researchers have tracked accelerations that have exceeded 100 times the acceleration of gravity ("100 G's"). By tracking such violent impacts and subsequently doing clinical observations of players, they say they can obtain information that has never been available previously.

"In the past, we put helmets on dummies and tried to re-create forces, but that's essentially guesswork," Duma said. "This is the first study to go out in a real game and measure what the head sees."

Much of their effort has been spurred by the knowledge that many athletes continue to play after sustaining concussions, often staying on the field when they don't know where they are or what day it is. A case in point, the researchers said, occurred in a highly-publicized incident earlier this year when St. Louis Rams quarterback Kurt Warner remained on the field after sustaining a serious concussion.

Engineers said that the knowledge gained from the HIT system could be used by helmet engineers, as well as by physicians and team trainers. Equally important, the engineers hope to bring the technology down to lower level football programs, where it could be used in real time to monitor athletes.

"It would be very easy to work this into a wireless system that would page the trainer on the sidelines after a hard impact," Duma said. "Then the trainer could watch the player to see if he needed to leave the field."

To do that, however, Simbex would have to reduce the cost of the system. Although prototypes cost about $2,000 per helmet, engineers said the system price could realistically be reduced to less than $100 per helmet with sufficient volume.

"Our goal is to trickle the technology down to the high school and youth level," said Chu of Simbex.

Chu said the company also foresees the technology's use in hockey and in "un-helmeted" sports, such as soccer. In soccer, he said, sensors could be placed in headbands to tell if a player sustained a concussion while "heading" the ball.

Engineers also foresee a potential entertainment application for the technology in televised football games. Simbex engineers have already built a prototype, tentatively known as the "Hit-O-Meter" or "Slobberknocker," which could be used to gauge the impact of a hit to the chest during a pro football game.

Said Duma: "We could just imagine John Madden saying, 'Look at that. There's been five slobberknockers tonight.'"