A systematic decision-making method for evaluating design alternatives of product service system based on variable precision rough set

Product service systems (PSS) have led global manufacturers to change from providing product only to offering both product and its services as a whole. The existing decision-making methods have difficulties in evaluating design alternatives systematically during PSS conceptual design process involving cognition vagueness and related complex factors. A new systematic decision-making method is developed for judging these alternatives. PSS is divided into multiple-modules associated with function characteristics and then evaluated by using the outputs of parallel houses of quality (HoQs). HoQs can efficiently deal with customer requirements and the relationships between product and service. A variable precision rough set-based approach is proposed to evaluate these alternatives, which can flexibly handle subjectivity and vagueness during the decision-making process. An optimizing model of least squares model is used to integrate individual judgments into a consensus group judgment. A non-deterministic ranking method is developed to identify optimal alternative based on the final judgments which are obtained by using a rough weighted geometric mean method. The proposed method is validated through a real-world case study for a horizontal directional drilling machine.