## 4 Proof of Concept Implementation
### Comparison Mechanism
This method is not always possible without encoding large amounts of additional knowledge and information in the transformation. This is similar to the methodology proposed by [PERSON] et al. [24] that requires a complete and consistent definition of an underlying formal system. Therefore, these approaches are unlikely to be feasible practically and economically. Also, the rules used by [PERSON] et al. [5] need to be maintained (i.e., revised and grown), resulting in possibly time-consuming and costly work. The different techniques identified in Spanoudakis [6] are based on fundamental concepts developed in model-driven software engineering research. Since a broader knowledge is required to develop mechatronic systems due to their multidisciplinary nature and the heterogeneity of a multitude of disparate models being used, these techniques cannot directly be applied in the process design and development of mechatronic systems. [PERSON] et al. [4] explored the fundamentals of consistency and relate these concepts to modeling and engineering design. However, the authors consider specific types of inconsistencies and the fundamental theory is not applied to an automated solution. The approach proposed a partial solution for consistency management since some inconsistencies may remain undiscovered. [PERSON] et al. [8] is limited to identifying inconsistencies, but they did not support the method by techniques to resolve them. [PERSON] et al. [7] presented a dependency modeling language to capture the dependencies between properties in multiple views of a system. Dependencies between these properties are interesting to identify inconsistencies between models but it is insufficient to manage consistency since it considers specific types of inconsistencies (i.e., related to properties). The resolution of inconsistencies is a manual process. This method is proposed as an aid for consistency management. While being less formal than the methodologies proposed in the literature, we assume that our methodology is a more flexible alternative, since it uses a common representational formalism to abstract models and uses a comparison algorithm allowing easier and quicker detection of different differences and inconsistencies between models without the need of a complete knowledge of an underlying formal system. The overarching goal of our research is to manage the consistency between different domain-specific models of a mechatronic system in order to deliver viable models in a shorter period of time. Our approach is used to improve the V-cycle systems engineering process for mechatronic development. Traditionally, inconsistencies are identified as a part of the verification and validation (V&V) process. The time interval between V&V activities is usually very long. Therefore, the cost associated with solving inconsistencies can be very high. According to INCOSE [42], errors are less costly to remove early in the life cycle. Based on statistical analysis, eliminating the detected design errors during the design phase is 6 times more expensive than removing them in the early concept phase. This number can be multiplied by 100 and 1000 if the design errors are detected during the development, production, or test stages. Consequently, the earlier an inconsistency is identified during the life cycle process, the cheaper it is to fix. Therefore, we propose a continuous and (semi)automatic method of managing inconsistencies to remove inconsistencies early in the life cycle and to positively support the V&V process. However, as shown in the previous sections, the changes of the models are determined by the project manager who has a global knowledge of the various models. Hence, the comparison phase is a semiautomatic process. This assumption makes the process dependent on the project manager and thus relatively centralized. For example, they intervene in checking the consistency between models and they are responsible for proposing appropriate changes, defining correspondences between label components.