In this meeting of the AI Seminar Series, we shall hear from Dr. Christina Burt and Dr. Nir Lipovetzky.

Title:Planning for Mining Operations with Time and Resource Constraints

Speaker:Dr. Christina Burt and Dr. Nir Lipovetzky

When: Tuesday, 3rd June 11 AM - 12 NOON

Where: Doug McDonnell-10.05

We study a daily mine planning problem where, given a set of blocks we wish to mine, our task is to generate a mining sequence for the excavators such that blending resource constraints are met at various stages of the sequence. Such time-oriented resource constraints are not traditionally handled well by automated planners. On the other hand, the remaining problem involves finding node-disjoint sequences with state-dependent travel times on the arcs, which are highly challenging for a Mixed-Integer Program (MIP). In this paper, we address the problem of finding feasible sequences using a combined MIP and planning based decomposition approach. The MIP takes care of the resource constraints, and the planner solves the remaining sequence problem. We extend the notion of finding feasible sequences to finding good feasible sequences, by devising a heuristic objective function in the MIP, which improves the resulting search space for the planner. We empirically analyse the scalability of our approach on a benchmark data set, before demonstrating its effectiveness on a real world case study provided by our industry partner. These results demonstrate that by using a heuristic MIP, it is possible to obtain better makespan results with a suboptimal planner than by using an optimal planner with an uninformed MIP.

Christina obtained her Ph.D with Chancellor's commendation on mixed-integer programming approach to Equipment Selection in Open Pit mining. She has studied transportation related problems in the context of mixed-integer programming at both The University of Melbourne and at the Austrian Institute of Technology. She currently studies mixed-integer nonlinear problems associated with Open Pit Mine Scheduling.

Nir obtained his Ph.D on Automated Planning at Universtiat Pompeu Fabra, Barcelona. His research is in the area of Automated Planning, Heuristic Search and Models of Reasoning and Learning, with a special focus on how to introduce different approaches to the problem of (tractable) inference in planning. Currently he's studying planning problems associated with Open Pit Mine Scheduling.