CUE 2008 >> Features >> Unmanned Vehicles: Micro-Air Vehicles Flock to Collect and Transmit Data

CUE 2008

Aerospace Engineering Sciences:

Unmanned Vehicles: Micro-Air Vehicles Flock to Collect and Transmit Data

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CU aerospace faculty Kamran Mohseni and Dale Lawrence are part of a team that is developing micro-air vehicles to collect and transmit environmental data. The team has focused on small MAVs that could be flown semi-autonomously at low cost in flocks or swarms. Other CU researchers are working on larger unmanned vehicles, such as the Aerosonde, a commercial aircraft, which they adapted to be able to fly scientific missions in the Arctic

A flock of unmanned aerial vehicles as small as birds, fanning out over a wide area to cooperatively gather and transmit scientific data—that’s the vision of a CU engineering team that has become the first in the world to demonstrate a wireless sensor network composed of semi-autonomous micro-air vehicles, or MAVs.

A retargetable "sensor flock" comprised of dozens or even hundreds of MAVs offers attributes that could be very attractive to scientists, according to Dale Lawrence, one of three CU faculty working together to achieve the feat.

Environmental monitoring of tornados, hurricanes, wildfires, wildlife, and ecological systems could be accomplished much more easily with MAVs, which could perform three-dimensional sampling at a low cost and in a short amount of time, he says. The MAVs designed and built by the CU team cost less than $600 each, compared to tens of thousands of dollars for a large unmanned aircraft.

Lawrence and Kamran Mohseni of aerospace engineering sciences are teaming with Richard Han of computer science on the multidisciplinary project. Lawrence brings expertise on navigation and control systems, Mohseni on platform, and Han on wireless communication networking. A half dozen CU students also are involved.

The team, led by Mohseni, won a four-year, $1 million grant from the National Science Foundation in 2004, which resulted in a successful field test of the vehicles last fall. Five MAVs, weighing 580 grams each (less than 20 ounces) with a wingspan of 70 centimeters (28 inches), were flown semi-autonomously, and an in-depth study of air-to-air communications was conducted.

The vehicles followed high-level instructions from a ground-based controller, while making simpler piloting decisions on their own during flight. The MAVs were able to maintain "loiter circles" around their target point using onboard controls and to relay information to the ground using RF signals while banking and rolling in flight. A loiter circle is the term used to describe the vehicle’s normal operating mode when it has reached its destination and is awaiting higher-level instructions from the base station.

"It’s a major achievement that they actually built the system and made it work," an Israeli aerospace engineer told New Scientist after the CU team presented its results at the Association for Computing Machinery’s Conference on Embedded Network Sensor Systems in Sydney, Australia.

The research team is scaling up the experiment this spring to include 10 MAVs, multi-hop communications over a longer range, and incorporation of chemical sensors on each vehicle to support another possible application—monitoring toxic plumes. In the envisioned scenario, the MAVs would balance onboard controls with directions from the ground controller so as to follow a moving plume and make continued observations.

The team is working with the Federal Aviation Administration to get formal approval so that the larger test can be conducted.

In the meantime, Mohseni has been working on a smaller vehicle with mylar wings, weighing only 40 grams (1.4 ounces) with a wingspan of 15 centimeters (six inches), which he says could potentially fly for as long as an hour.

A later goal of the project is to incorporate a system of unmanned underwater vehicles working in concert with the aircraft to gather sensory data below the ocean’s surface and relay it to shore, he adds. Mohseni has been working on biomimetic mechanisms to improve the propulsion and maneuverability of underwater vehicles for automated docking, and he is collaborating with researchers at the University of Southern California on wireless communication and networking so the vehicles could be used to track hurricanes and forecast their trajectories.

CU engineering faculty have been involved in unmanned vehicle research and development for about a decade and have designed and built several semi-autonomous vehicles. CU faculty also adapted the Aerosonde, a commercial vehicle with a three-meter wingspan well suited to long-duration flights, to collect scientific data in remote areas of the Arctic. Associate Research Professor Jim Maslanik worked with the NSF to mitigate aircraft icing and prove the Aerosonde’s ability to operate in the polar environment through numerous long-distance missions out of Barrow, Alaska.

UAVs offer many benefits over satellites for monitoring sea ice and ocean conditions, Maslanik says, including finer spatial resolution and the ability to collect data under cloud cover. "MAVs also could have applications in the polar region because of their low cost," he notes, such as performing reconnaissance missions for ships to help them avoid major ice floes.

Research group website: http://enstrophy.colorado.edu/~mohseni/MicroVehicles1.html