Several Leader-follower Joint Optimization Problems For Product Design

Owing to its advantages in effectively providing product variants at reduced costs to meet particular customer requirements,product family design and platform-based product development have been well recognized as effective strategies to enable mass customization.Optimization methods and intelligent algorithms have been widely developed,and then applied to decision makings of product lines and product families in the process of design and development.Recent applications of bilevel optimization in product family design have indicated the potential of leader-follower joint decision models based on the Stackelberg game.In this thesis,several leader-follower joint optimization problems in product line design and product family deisgn have been addressed based on the Stackelberg game theory and bilevel optimization technology,and the main work is divided into the following five parts:(1)Related literatures are reviewed,including the holistic framework of product family design and development,optimization methods in product family design,product line design optimization and competitive product line design,make-or-buy decisions and supplier selection problems,as well as Bilevel optimization and its application in the product design.(2)A leader-follower bilevel optimization model is formulated for the competitive product portfolio management problem based on the Stackelberg game.In the absence of a closed-form solution,the model is illustrated through a numerical case under different market scenarios,including sensitivity analysis of some key parameters,and calculated results are compared with Nash equilibria.(3)A decision framework with one leader and multiple followers is proposed for the competitive product line design problem based on the Stackelberg-Nash game,where the new entrant is a leader and the incumbent firms are followers.Consistent with the leader-followers decision structure,a bilevel zero-one integer nonlinear programming model is formulated,and a nested bilevel genetic algorithm with the sequential tatonnement procedure is developed to find the corresponding Stackelberg-Nash equilibrium.An industrial case of mobile phone product is also presented to illustrate the feasibility and potential of the proposed leader-followers model and algorithm,and experiments are designed to compare the Stackelberg-Nash equilibrium with traditional product line design strategies without considering competitive reactions,as well as the Nash equilibrium derived by the sequential tatonnement procedure.(4)Product family architecting considering make-or-buy decisions is proposed to be formulated as a Stackelberg game,in which a bilevel decision mechanism model is deployed to reveal the inherent coupling and hierarchical relationships between product family architecting and make-or-buy decisions.A nonlinear bilevel optimization model is developed with the product family architecting problem acting as the leader and the make-or-buy decision performing as a follower.A nested genetic algorithm is developed to solve the bilevel optimization model.A case study of power transformer product family architecting subject to make-or-buy considerations is presented to illustrate the feasibility and effectiveness of bilevel joint optimization,and two experiments are designed to compare the obtained results with those results derived from a traditional ?all-in-one? optimization model and a two-stage method.(5)The joint optimization of configuration design and outsourcing decision for a product family is regarded as a distributed collaborative decision-making,for which a Stackelberg game theoretic decision framework is proposed to model the dynamics between configuration design and outsourcing decision.Consistent with Stackelberg game,a nonlinear bilevel optimization model with a common deviation function,compromising an upper-level configuration design optimization and a lower-level outsourcing decision optimization,is formulated.A nested bilevel genetic algorithm is developed to solve the optimization model.A case study of coffee grinder product family design considering outsourcing decision is reported to illustrate the feasibility and potential of the proposed distributed collaborative game-theoretic approach,and four experiments are designed to compare the obtained solution with those derived by solving the configuration design problem and the outsourcing decision problem subsequently using the traditional two-stage method,as well as by maximizing the market share,minimizing the engineering cost,and minimizing the outsourcing cost separately.