Volume 2, Issue 6 August 2002

2002
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2001
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Eye in the Sky by David Pescovitz Multimedia Movie: Pursuit-Evasion Game with both aerial and ground robots. (MPG movie) Movie courtesy Berkeley Aerobot A model helicopter is gently hovering in the sky above a field at the UC Berkeley Richmond Field Station. Slowly, it begins its decent onto a landing platform secured to a trailer. The landing is precarious – like the pilot is new to the hobby – but ultimately successful. Onlookers cheer but the pilot is nowhere to be found. That's because the pilot is a computer. The Berkeley Aerobot (BEAR) is an autonomous aerial robot, designed to fly and navigate and recognize and locate target objects on its own accord. "You could imagine hundreds of these being deployed to fight fires or conduct search-and-rescue machines," says T. John Koo, visiting faculty at Berkeley's Department of Electrical Engineering and Computer Sciences (EECS) and a principal investigator of the Aerobot project. "With that many helicopters flying, the number of people involved in operating them must be reduced. Basic robotic functionality enables humans to worry about more high-level tasks like where the helicopter should go and what it should look for." T. John Koo in his laboratory with a prototype Aerobot. (Click for larger image.) David Pescovitz photo The Aerobot first took flight in 1998. Koo, then a Berkeley Engineering graduate student, spearheaded the University's first entry into the Aerial Robotics Competition with support from EECS department chair Shankar Sastry, still the faculty leader on the Aerobot project. Today's Aerobots – based on the airframes of remote-controlled crop-dusting or hobbyist helicopters – are a tour-de-force of computer vision, embedded software, and control systems. Employing Global Positioning Satellite technology that provides location information down to two centimeters, the Aerobot steers itself to any pre-determined waypoint. Then, advanced computer vision technology developed at Berkeley kicks in to guide the helicopter safely back to Terra Firma. But landing on the ground looks like childsplay compared to one of the other research objectives. Funded in part a grant from the Defense Advanced Research Projects Agency's Software-Enabled Control program, the Aerobot is expected to be agile enough to land on a moving aircraft carrier. As a testbed, the Berkeley team designed a mechanical landing platform that simulates the rock and sway of a ship on the open sea. Indeed, simulation plays a key role in the Aerobot research. The majority of Aerobot experimentation takes place indoors on computer screens. One PC runs the helicopter's software code while another emulates the dynamics of the helicopter and its onboard GPS and intertial/navigational sensors. Other variables – a digital representation of wind, for instance – add to the model's realism. Robots in the sky: science fiction or a new kind of superhero? We want to hear from you... "Using extensive computer simulation with hardware in the loop, we can test the entire system without risking the expensive experimental helicopters," says Koo, adding that a fully-outfitted prototype Aerobot can cost in the tens of thousands of dollars. The latest addition to the Aerobot's test regimen are Pursuit/Evasion Games. The games consist of an Aerobot collaborating with several ground-based mobile robots to chase a "renegade" mobile robot. Whoever locates the evader first guides the others to the location — not unlike a police chase on the Los Angeles freeway, albeit much slower. The Aerobot team's future computer vision research goals focus on combining the GPS-based control system with 360 degree videocamera technology for path planning and aerial obstacle avoidance. Koo believes the Aerobot is ideal for locating objects other than errant vehicles though. With the intense accuracy of their onboard GPS system and the integration of additional sensors, Koo says the Aerobots could fly inches over terrain and pinpoint the location of undetonated mines. Another application Koo envisions is robotic firefighting. For instance, a continuous swarm of Aerobots could dump water on a forest fire without the risk of collision in dense smoke, he says. While real-world Aerobot applications are still several years away, Koo is looking at other potential benefits of his embedded software and control systems research. All aircraft, he explains, could benefit if the numerous automated tasks – such as the angle and speed changes that must be taken into consideration when landing – were better orchestrated to achieve a high-level goal. To that end, the Aerobot group is collaborating with industry partners like Boeing, Northrop-Grunman, Honeywell, and Rockwell "to make aircraft safer and more efficient." "Sensors and actuators are the interfaces between computers and the real world," Koo says. "But we need those two worlds to be tightly coupled." Berkeley Aerobot T. John Koo's Home Page Lab Notes is published online by the Public Affairs Office of the UC Berkeley College of Engineering. The Lab Notes mission is to illuminate groundbreaking research underway today at the College of Engineering that will dramatically change our lives tomorrow. Editor, Director of Public Affairs: Teresa Moore Writer, Researcher: David Pescovitz Designer: Robyn Altman Subscribe or send comments to the Engineering Public Affairs Office: lab-notes@coe.berkeley.edu. © 2002 UC Regents. Updated 7/25/02.