Monday, December 12, 2011

#MEMS: "Smart Arrows Report Flight Stats"

Using micro-electro-mechanical system (MEMS) accelerometers in arrows, smart archers now can precisely record the speed, distance and other flight statistics for their shots.

Archery is the latest sport to aid athletes by equipping arrows to record an archer’s performance for later review. By mounting a micro-electro-mechanical system (MEMS) accelerometer inside the tip of an arrow, archers can now take advantage of the same motion processing algorithms that have already revolutionized other professional sports.
Smart arrows embed a MEMS accelerometer in their tip to sense flight characteristics such as speed and distance. (Source: Analog Devices)
Surfing and snowboard/skiing were recently revolutionized with micro-electro-mechanical system (MEMS) sensors that record performances. Now archery is joining the instrumented sports arena by virtue of a MEMS accelerometer from Analog Devices Inc. (ADI).
The MEMS accelerometer is small enough to be built into the tips of smart arrows. ADI already supplies much of the world's need for high-performance inertial MEMS chips--such as accelerometers and gyroscopes--with design wins in everything from high-precision military munitions to instrumenting a special suit to track the motions of Ironman actor Robert Downey.
Accelerometers can track the location, speed and distance traveled by objects to which they are attached by measuring the inertial forces in all three spatial planes. The ADXL346 accelerometer used for smart arrows, for instance, is a three-axis device that measures motion in the X-, Y-, and Z-planes, then stores the values in an on-chip FIFO (first-in, first-out) memory.
The smart arrows manufactured by ADI customer Full Flight Technology capture the ballistic motion of an arrow from the moment it is shot to its impact with the target. Called the Velocitip Ballistic System, it is the first use of ruggedized accelerometers which are attached directly to the business-end of a sports system. For instance, the surfboard and snowboard accelerometers track the relatively benign motions of the athlete, whereas the smart arrow experiences violent motions that would be impossible for athletes to survive.
Arrows experience launch forces of 1,000-Gs at launch and over 4,000-Gs on impact, but tests show that smart arrows can nevertheless survive up to 100 shots while using power from a single coin-cell battery pack. The standard nine millimeter diameter smart arrow tip weighs less than 6.5 grams and provides 13-bit resolution measurements of the speed, distance and other flight statistics.
After shooting, the archer unscrews the smart arrow tip and plugs it into a handheld docking station which reads out the performance data, transfers it to the archer’s PC, and resets the smart arrow. No other equipment is required, unlike existing arrow flight measuring systems that require external equipment to track arrows.
Further Reading