Yenra : Air Travel : Personal Air Vehicle : Inertial measurement unit provides full six-degree-of-freedom motion sensing for navigation and control systems

Personal Air Vehicle

Crossbow Technology is playing a key role in two of the world's most ambitious manned flight applications. Crossbow inertial guidance systems are at the heart of the record-breaking Virgin Atlantic Global Flyer from Scaled Composites and the Springtail one-man air vehicle from Trek Aerospace. Both the Global Flyer and the Springtail use off-the-shelf intelligent sensing solutions from Crossbow, products designed to save time and money for Crossbow's aviation customers.

In March of this year, pilot Steve Fossett successfully guided the Global Flyer to the first solo round-the-world flight, completing the non-stop voyage in just over 67 hours. The Global Flyer, billed as the world's most fuel-efficient jet airplane, relied on Crossbow's Altitude and Heading Reference System (AHRS) for primary flight attitude and heading guidance. The AHRS500GA is the world's first stand-alone MEMS-based AHRS to receive FAA certification.

"The Global Flyer placed demands on the Crossbow AHRS that were unlike any other airborne application. After nearly three days of non-stop operation, our product performed perfectly and gave the pilot reliable, accurate information all the way around the world," said Mike Horton of Crossbow. "When we designed this AHRS, we never imagined that it would be used to guide a solo pilot in a world-record flight. The Global Flyer's success makes us very proud."

The Springtail is a single operator powered-lift vehicle developed by Trek Aerospace. Reminiscent of the jet packs of the 1960's, Springtail can take-off and land almost anywhere. The operator steps onto the vehicle and rides in a standing position just beneath a pair of ducts, each of which contains a fan. These ducted fans generate the thrust which allows the vehicle to get airborne. Trek's unique design allows their ducted fans to achieve an amazing eight pounds of thrust per horsepower -- twice the nearest competitor.

Springtail is operated by an advanced fly-by-wire computer control system. The fans are counter-rotating, eliminating the torque that is normally associated with a single rotor, making the vehicle easier to fly. The ducts and fans tilt, individually, to increase forward speed and provide directional control.

Vanes mounted in the ducts, just below the fans, are also used for directional control. The gasoline engine is mounted just behind the operator for easy access.

At the heart of the Springtail's control system is Crossbow's IMU400 6DOF, an Inertial Measurement Unit that provides full six-degree-of-freedom (6DOF) motion sensing for navigation and control systems. Angular rate and acceleration are measured about three orthogonal axes. The Crossbow IMU400 6DOF is a solid-state IMU utilizing the latest MEMS micro-machined sensing technology combined with digital signal processing to provide reliable, easy-to-use inertial systems in a small, lightweight package.