The next ten years will see at least five NASA/JPL missions to the planet Mars. The 1997 Pathfinder mission was very successful; some of the subsequent missions, less so. The latest NASA landing mission launched on 10 June 2003 and will arrive at Mars on 4th January, 2004. The current technology is the same as the Pathfinder mission and involves entering the atmosphere on a ballistic trajectory. Such trajectories are essentially open-loop giving a landing error ellipses of 300km x 150km. Future science requirements, for example sample return for exobiology, dictate an increasing precision in the landing point. This in turn necessitates feedback control during the atmospheric entry; flying a wingless vehicle with dynamics more resembling a cannonball than a plane. Aeromanoeuvring without wings at planetary entry velocities in a highly uncertain atmosphere poses an interesting nonlinear control problem. The issues that arise, and the control structure employed, will be discussed. This is on-going work, in conjunction with JPL, and the current approach will be illustrated by a 3D simulation. The longer term objectives are landing error ellipses of 10 km, and ultimately, 1km or less.
Brief bio of speaker: Roy Smith received the BE and ME (Hons) degrees from the University of Canterbury in 1980 and 1981 respectively. He has worked for a variety of government laboratories, industrial companies and consultancies in New Zealand and California on: automotive engine control systems, instrumentation and automation of mass spectrometers and linear accelerators; and industrial boiler systems.
After completing a PhD at Caltech in 1989, he spent a year teaching at Caltech and doing research at JPL on the design of vibration supression systems in large space telescopes. In 1990 he joined the Electrical and Computer Engineering Dept. at the University of California, Santa Barbara, where he now holds the rank of Professor.
Roy Smith's research interests include the identification and control of uncertain (and possibly nonlinear) systems; process control problems, including rapid thermal processing and semiconductor deposition; automotive control systems; flexible space structures; aeromanoeuvring spacecraft; formation flying of space vehicles, and magnetically levitated bearings.
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