Employing an interval type-2 fuzzy logic and hesitation index in a Multi Criteria Group Decision Making system for lighting level selection in an intelligent environment

Selecting a suitable lighting level for reading is crucial to the overall success of reading comprehension. The light level preferences vary amongst the various users specifically according to changing environment conditions. Hence, there is a need to employ intelligent decision making systems which can consider the various preferences and criteria in order to achieve the convenience of the various readers. In this paper, we propose a Fuzzy Logic-Multi Criteria Group Decision Making (FL-MCGDM) system which provides a comprehensive valuation from a group of decision makers. The decision making system was developed based on the aggregation of users´ opinion on preferred lighting levels while reading. The proposed FL-MCGDM system employs an interval type-2 fuzzy logic and hesitation (from Intuitionistic Fuzzy Sets (IFSs)) index. We have carried out various experiments in the intelligent apartment (iSpace) located in the University of Essex. It was found that the Footprint of Uncertainty (FOU) (of interval type 2 fuzzy sets) and hesitation index of intuitionistic fuzzy sets (IFSs) are able to provide a measure of the uncertainties present among the various decision makers in the proposed FL-MCGDM system. The extended (Type-2-IFS) membership function in the FL-MCGDM system is more inline/agreement with the users´ decision compared to type-1 membership function and interval type-2 membership function.