Servo - May 2009

ACE Lab http://ace.utsa.edu/index.html

Resources

ACE Research http://ace.utsa.edu/research.html

ACE Autonomous Underwater Robotics http://ace.utsa.edu/water.html

ACE Unmanned Air Vehicles

http://ace.utsa.edu/uav.html

successful swarms include wireless communications by which the robots become aware of each other. Frequently, the robots are aware of their location in relation to the locations of the other robots. In many approaches to swarm robotics, location awareness is important to cooperation and dividing the various elements of the task at large.

The third level deals with the degree to which robots act with regard or disregard for the actions of others in the swarm. The more strongly the robot swarms are coordinated, the more effective they become. Finally, people organize swarms in one of a few ways: either researchers make them distributed with each acting autonomously, or they make them centralized with a leader among them. Weakly centralized swarms — which fall somewhere in the middle — have more than one leader or “master” robot. The UTSA swarm robots use multiple masters and distributed decision-making.

In their work at UTSA, scientists include a larger hierarchy in which swarms of land, air, and sea robots are coordinated from a network as part of a larger swarm that encompasses them all. Researchers call this a system of systems approach.

Fixed Wing UAVs

In UTSA’s UAV research, two fixed wing unmanned

GEERHEAD

The autonomous fixed wing craft in flight.

airplanes serve — with one as the master robot — providing coordinates to quad-rotor UAVs (the Dragonfly used here is an unconventional helicopter design with four perpendicular rotors and motors). Coordinates and technical facility include image recognition technology, inter- and intra-craft communications, GPS locations, flight altitude and area mapping for a surveillance task.

Because the fixed wing UAVs must cover large areas with relatively large payloads (three lbs in one case), the scientists constructed them with large wingspans and wing areas. The master fixed wing robot has a wingspan of 69 inches and covers a wing area of 793 square inches, according to the UTSA ACE lab. This robot carried a 2 lb payload including a video camera, data link transmitter, an FM receiver, and batteries.

The UAV is equipped with an autopilot board with three-axis gyros and accelerometers, a GPS system, a pressure altimeter, and airspeed sensors. The control board is extendable with ultrasonic sensors for autonomous takeoff and landing. The airplane uses a radio modem to send out a live telemetry feed.

The second UAV has an 80 inch wingspan and 1,180 square inches of wing area, making it capable of taking off with a 3 lb payload. This second fixed wing vehicle carries a flight control board, an Inertia Measurement Unit, a GPS, a modem, a video camera, a 5 channel receiver and its