# A Trimming Design Method Based on Bio-Inspired Design for System Innovation
## 1 Introduction  
In today's fiercely competitive market, companies largely depend on innovation to succeed, and refined design is one of the most important routes to achieving product innovations. As a method for solving refined design problems, trimming, which originates from the Theory of Inventive Problem Solving (TRIZ), has become a widespread method to realize product innovations. In the process of trimming, selected components of the system are removed, and useful functions are reallocated to residual system components or super-system resources [1]. The objective of trimming is to use existing resources after removing harmful components while streamlining design schemes, resulting in improved system ideality. However, solutions to trimming problems strongly depend on the knowledge and experience of designers, as trimming usually transforms contradiction problems into \"how to\" formulations that require the innovative use of resources to rebuild trimmed systems, which is a key design issue and a frequent difficulty for designers [2, 3]. Trimming is applied to solve different types of inventive problems, from detailed component pattern improvements to system-level redesigns [4]. An innovative process that involves trimming requires more knowledge, potentially cross-industry and interdisciplinary knowledge, for problem solving [5]. However, existing resources are rarely directlyused to solve trimming problems due to limitations in designers' knowledge, thus hindering the generation of high-quality design solutions. When using the trimming method to solve innovative problems, engineering designers mainly rely on their professional experience to search for and identify suitable resources. In most cases, they need to retrieve potential knowledge from outside their professional fields, which is a difficult task. Aiming to establish a method for identifying potential available resources after trimming, this paper combines trimming with bio-inspired design (BID). The objective of this method is to provide guidance for designers by introducing biological strategies to the innovation process so that they can quickly identify potential available resources and reallocate functions in the trimmed system. Bio-inspired design (BID) is widely regarded as a feasible method for obtaining product design ideas based on biological systems, and it has yielded innovations in different areas [6; 7; 8; 9]. Although it is a knowledge domain that differs from engineering design, biology can play an important role in stimulating breakthrough innovations in engineering. In order to increase the applicability of biological solutions to engineering problems, they are often processed and represented using function-based models, such as Design Analogy to Nature Engine (DANE) [10] or multi-biological effects (MBE) [11], which reveal the features of their functional design. The results of some studies [12; 13] suggest that the application of biological solutions to an engineering design can indeed improve its novelty. Thus, biological knowledge can be used as a long-term resource to solve trimming problems. However, a drawback of BID is that a practical scenario is necessary to overcome interdisciplinary obstacles before biological strategies can be transformed into technical solutions. Trimming offers advantages in scenarios involving transformed design problems. For example, after trimming invalid components from the system, \"performance\" problems can be transformed into \"functionality\" problems [3; 4; 5]. Therefore, trimming seems to be a feasible method for creating suitable design scenarios that facilitate the introduction of biological information to solve inventive problems. In summary, this paper proposes a new design method that combines the trimming process with BID to solve the shortcomings of existing methods. First, a function analysis and Cause-Effect Chain Analysis (CECA) are used to analyze the target system, determine the trimming objects and their priorities, and identify missing useful functions after trimming.