Multi-Horizon Multi-Agent Planning Using Decentralised Monte Carlo Tree Search

We propose multi-horizon Monte Carlo tree search (MH-MCTS), the first framework for integrated hierarchical multi-horizon, multi-agent planning based on Monte Carlo tree search (MCTS). The method employs multiple simultaneous MCTS optimisations for each planning level within each agent, which are designed to optimise a joint objective function. Using concepts from decentralised Monte Carlo tree search (Dec-MCTS), the individual optimisations continuously exchange information about their current plans. This breaks the common top-down only information flow within the planning hierarchy and allows higher level optimisers to consider progress made by lower level planners. The method is implemented for survey missions using a fleet of ground robots. Simulation results with different mission profiles show substantial performance improvements of the new method of up to 59% compared to traditional MCTS and Dec-MCTS.