Multi-level requirement model and its implementation for medical device

Abstract

Requirements determine the expectations for a new or modified product. Requirements engineering involves defining, documentation and maintenance of requirements. The rapid improving of technologies and changing of market needs require a shorter time to market and more diversified products. As an important and complex task in product development, it is a huge work to develop new requirements for each new product from scratch. The reusability of requirements data becomes more and more important. However, with the current “copy and paste” approach, engineers have to go through the entire set of requirements (sometimes even more than one set of requirements) to identify the ones which need to be reused or updated. It takes a lot of time and highly relies on the engineers’ experiences. Software tools can only make it easier to capture and locate the requirements, but won’t be able to solve the problem of effective reuse of the existing requirement data. The overall goal of this research is to develop a new model to improve the management of requirements and make the reuse and reconfiguration of existing requirements and requirement models more efficient. Considering the requirements data as an important part of the knowledge body of companies, we followed the knowledge categorization method to classify requirements into groups, which were called levels in the study, based on their changing frequency. There are four levels, the regulatory level, the product line level, the product level and the project level. The regulatory level is the most stable level. Requirements in this level were derived from government and industry regulations. The product line level contains the common requirements for a group of products, the product line. The third level, product level, refers to the specific requirements of the product. And the fourth and most dynamic level, the project level, is about the specific configurations of a product for a project. We chose auto-injector as the application to implement the model, since it is a relatively simple product, but its requirements cover many different categories. There are three major steps in our research approach for the project. The first is to develop requirements and classify them for our model. The development of requirements adopts the goal-oriented model to analyze and SysML, a system modeling language, to build requirements model. And the second step is to build requirements template, connecting the solution of the problem to the information system, standalone requirements management tool or information platform. This step is to find a way to realize the multi-level model in an information system. The final step is to implement the model. We chose two software tools for the implementation, Microsoft Office Excel, a commonly used tool for generating requirements documents, and Siemens PLM suite, Teamcenter, a world leading PLM platform with a requirement module. The results in the study include an auto-injector requirement set, a workflow for using the multi-level model, two requirements templates for implementation of the model in two different software tools, and two automatically generated requirement reports. Our model helps to define the changed part of requirements after analysis of the product change. It could avoid the pitfalls of the current way in reusing requirements. Based on the results from this study, we can draw the following conclusions. A practical multi-level requirements management model can be used for a medical device—the auto-injector; and the model can be implemented into different software tools to support reuse of existing requirement data in creating requirement models for new product development projects. Furthermore, the workflow and guideline to support the application and maintenance of the requirement model can be successful developed and implemented. Requirement documents/reports can be automatically generated through the software tool by following the workflow. And according to our assessment, the multi-level model can improve the reusability of requirements.