You contribute to the enrichment of the ExpressIF platform by working on the automatic planning component. Automatic planning is a branch of AI which is concerned with planning the missions of an automaton to accomplish a given objective. HTN planning (Hierarchical Task Network) is an approach which, compared to traditional approaches, allows a richer representation of business knowledge, and is computationally more efficient, hence its use for solving concrete problems. We wish to contribute to work that focuses on planning under uncertainties and with preferences in the HTN framework. We propose to use fuzzy logic as a knowledge representation framework. Preferences can for example be in the choice of the method of decomposition of an abstract task.