Motion-based musical interfaces are ubiquitous. With the plethora of sensing solutions and the possibility of developing custom designs, it is important that the new musical interface has the capability to perform any number of tasks. This paper presents the theoretical framework for defining, designing, and evaluation process of a physical gesture acquisition for Guqin performance. The framework is based on an iterative design process, and draws upon the knowledge in Guqin performance to develop a system to determine the interaction between a Guqin player and the computer. This paper emphasizes the definition, conception, and evaluation of the acquisition system.