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Ultimate Testing

Ultimate Testing

A football player receives a brutal head impact that makes on-lookers cringe. Of course the player has some cobwebs but was he injured? Today, team physicians, trainers, and coaches are forced to make decisions about a player's condition based on little or no data. But that could change, thanks to the efforts of engineers at Simbex (Lebanon, NH). Last season, they provided a wireless instrumentation system to the Virginia Tech Hokies football team, allowing researchers to read and evaluate the head impact data. Using eight helmets in rotation, researchers were able to gather data on 38 players in all positions. Over 3,300 impacts were recorded over the entire season. The ongoing accumulation and analysis of data will provide researchers with a better understanding of the biomechanical factors that lead to concussions and to redefine injury limits for the human brain.

The Challenge

Take numerous, real-time impact measurements without distracting the player and transmit the information to a remote data collection and monitoring site.

The Solution

The result of more than 10 years of R&D, the Simbex Head Impact Telemetry System (HITS) initiates the data collection with six low-cost, micro electromechanical system (MEMS) accelerometers mounted in the football helmet. Spring-loaded buttons in contact with the player's head convey the impact force information to 120g accelerometers from Analog Devices. The analog readings are sent to the 8-bit A/D converter of a Hitachi H8 microcontroller. With the 8-bit A/D and the accelerometer, the system achieves about plus or minus 1g accuracy ( plus or minus 1 bit error). External E2PROM allows storage of about 128 impacts. Two molded AAA nickel-metal hydride batteries power the system. HITS transmits the raw data, the full-time periods from all six accelerometers, via RF to a laptop PC. The telemetry uses a proprietary RF technology operating in the 900 MHz industrial, scientific, and medical ISM band using an RF transceiver from Lab Partners Associates. Though engineers began development before any standard protocols really existed, they are keeping a close eye on mesh protocols in emerging standards such as Zigbee, due to the special data transmission issues related to rapidly moving end points.

Future Developments

This year Simbex added a notification function based off of predefined thresholds (which can be modified) for both impact and temperature. If the thresholds are exceeded for a particular hit, the system issues an alert through an alphanumeric wireless pager. The University of Oklahoma, now part of the research effort, is also interested in measuring core body temperature and comparing this data to the surface of the head to determine if any correlation exists. Now that they have working prototypes, engineers are looking at ways to reduce cost and ramp up for full production. Each prototype helmet currently costs $200.

Triple Play: The key components of the HITS: transmitter, helmet, and PC. The gray contact pads in the helmet identify the non-orthogonal locations for the accelerometers. Spring-loaded buttons keep the leadless chip carrier packaged accelerometers in contact with the player's head.

Web Resources
//Check out the links below for more info//
Simbex Head Impact Telemetry System (HITS):
Analog Device Accelerometers:
Renesas (formerly Hitachi) H8 MCU:
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