Aerospace engineers have always been stimulated by the natural world, and have built and flown many bio-inspired vehicles. Lockheed Martin Advanced Technology Laboratories (ATL), headquartered in Cherry Hill, New Jersey, is currently designing and prototyping the Samarai family of vehicles, which are inspired by maple seeds.
When maple trees shed their seeds each spring, they float gently to the ground. Their descent is stable and smooth because of their aerodynamically and mechanically simple design. Lockheed Martin ATL is designing, prototyping and flying a family of unmanned vehicles that mimics the flight of those seeds, taking the basic shape and harnessing it with flight controls and avionics including MEMS inertial sensors.
The guidance and navigation subsystem of the Samarai vehicles consists of the onboard sensors required both to support aerodynamic flight controls and to provide information to the operator to support higher level navigation commands. Flight control sensors provide information about Samarai motion states to support the flight control algorithms. Because of the high rate of rotation and the small size of the vehicle, traditional flight control sensors such as an inertial measurement unit (IMU) are not suitable for this application.
Instead, two modes of sensing are utilized for the flight control. First, a high-speed image sensor coupled with optical flow algorithms to derive vehicle motion parameters. And, second, a combination of MEMS accelerometer to derive vehicle pitch, roll, and vertical motion, and a magnetometer to derive rotation (yaw).
Two vehicles in the Samarai family are currently flying, measuring 30 and 12 inches respectively, and each has completed both human-guided and autonomous flight. Lockheed Martin ATL designed the vehicles as a family, and intends them to be easily scalable to meet the needs of different missions.
While there are many other designs for small unmanned vehicles, the Samarai flyer has some unique advantages. It's inherently stable in hover mode, mechanically simple and has very few moving parts. Because of its simplicity, an operator can just pull it out of a backpack and launch it. It can be launched from the ground or by hand.
The rotation of the entire aircraft allows the vehicles to achieve omni-directional sensing using simple optical, laser, or acoustic sensors.
The Samarai program began in 2005 and is currently funded through Lockheed Martin's internal research and development. The company believes that the technology could be ready for deployment in around two years. The primary missions envisioned involve search or surveillance of indoor or confined spaces; for these applications, the Samarai air vehicles could be used by warfighters, special forces, or civil first responders.
Copyright 2010 MEMS Investor Journal, Inc.