Task assignment with multiskilled employees and multiple modes for product development projects

In a product development project, efficiently assigning tasks to employees is difficult, since high level of design imprecision and employees with multiple skills and different skill levels exist. The relative skill levels of employees are modeled by fuzzy numbers, and membership function is introduced to describe the confidential levels of the duration the task takes. The employees' workloads in the project are calculated based on fuzzy sets theory and design structure matrix, and then multiple execution modes are generated by assigning different employees to the tasks. An optimization model of task assignment problem, which incorporates some factors not previously considered together (multiskilled employees and their skill levels, task iteration and the precedence constraints), is proposed. The objective function considered is to minimize the duration of the project and balance the workloads of the employees attending the project. Based on the information above, a genetic algorithm is utilized to find the optimum solution with regards to the considered objectives. A case of a die product development project is used to illustrate the problem and proposed method. The results verify the feasibility and effectiveness of this algorithm.