Laboratoire d'Analyse et d'Architecture des Systemes, Toulouse , France
25th September 2015, 2pm,
University of Edinburgh Business School, Lecture Theatre 2 (LG.18),
29 Buccleuch place, EH8 9JS, Edinburgh
Free registration here
Scheduling Philae's Science Campaign Using Constraint Programming
Abstract: On November 12th 2014, the robot-lab Philae was released from the spacecraft Rosetta and landed on the ground of the comet 67P/Churyumov-Gerasimenko. Philae is fitted with ten instruments to conduct the experiments elaborated by as many research teams across Europe. These experiments, should they be imaging, sampling or other types of signal analysis, correspond to sequences of activities constrained by two extremely scarce resources: the energy supplied by a single battery, and the storage memory of its CPU.
The plans executed by Philae are modelled and solved using constraint programming technology. Indeed, Mission Operations Scheduling Tool (MOST), the toolkit used to schedule the lander's activities, was developed by a CNES team based in Toulouse on top of IBM ILOG Scheduler (now IBM CP Optimizer).
I will present the contribution of our group to solving the problem of scheduling Philae's activities. In particular, I shall focus on the design of algorithms for efficiently reasoning about data transfers within Philae and between Philae and Rosetta. These algorithms made it possible to solve in a few seconds long term sequences of activities that otherwise required hours with the previous approach or in some case could not be solved. Moreover, they also give a more accurate prediction of the memory usage, thus giving better guarantees against data loss.
Biography: Emmanuel Hebrard is a CNRS* researcher at the Laboratory for Analysis and Architecture of Systems; University of Toulouse. He has got a Ph.D. from University of New South Wales.
His research interests cover many aspects of combinatorial optimisation in general, and constraint programming in particular, such as the design of solvers and algorithms for constraint propagation, SAT and clause learning, or the complexity and tractable classes of constraint satisfaction problems. Recently, his research was applied in projects with the space industry (CNES and Airbus Defence and Space).
(*) French "National Centre for Scientific Research
Organizer: R. Rossi
Coordinator: R. Rossi