Boundary Objects within the Discourse of Trustworthy Cyber-Physical Systems Development

Abstract

Cyber-Physical Systems (CPS) have progressed far beyond their origins in embedded control, evolving into large-scale software intensive systems that play an important role in modern society. By tightly integrating computation, sensing, control, and communication, CPS drive innovation across domains such as transportation, energy, healthcare, and industrial automation. As these systems become increasingly intelligent and interactive, often incorporating artificial intelligence (AI) and engaging dynamically with human users and their environments, new concerns arise regarding their trustworthiness. These concerns extend beyond traditional notions of dependability to include ethical considerations such as transparency, fairness, and accountability. As a result, ensuring classical dependability aspects while also addressing ethical dimensions of AI such as transparency, fairness, and accountability, is not only a technical challenge but also a socio-technical imperative. Consequently, the development of CPS requires interdisciplinary collaboration among stakeholders with diverse expertise. 

As the current development of CPS increasingly depends on interdisciplinary collaboration, the urgency of conducting effective co-engineering practices becomes ever more essential. However, this co-engineering practice is frequently challenged by knowledge boundaries stemming from differences in disciplinary languages, method, and interests. These boundaries can lead to misalignment and conflicting interpretations that disrupt co-engineering practices among the stakeholders involved. Addressing these challenges is a socio-technical endeavour that requires the integration of technical factors and social factors, particularly those that enable effective collaboration across disciplinary and organizational boundaries.

The concept of boundary objects provides a useful lens for tackling these issues. Originally introduced in the sociology, boundary objects are artifacts that are flexible enough to be interpreted differently across social worlds, yet robust enough to maintain a coherent identity. For example, they function as mediating structures that help align diverse perspectives, coordinate efforts across disciplinary boundaries, and facilitate negotiation of competing interests. In the engineering context, boundary objects may take the form of reference architectures that allow stakeholders to understand one another without requiring full consensus on meanings or methods. This combination of being flexible enough to adapt to local needs and constraints, while remaining stable enough to maintain a shared identity across different stakeholder groups, makes boundary objects particularly valuable for navigating the complexity and uncertainty of co-engineering practices.

This thesis investigates how reference architectures function as boundary objects that support co-engineering in the development of trustworthy CPS. Drawing on boundary object theory, it conceptualizes reference architectures as artifacts that enable translation across knowledge domains, mediate semantic and pragmatic boundaries, and provide a shared platform for e.g., negotiating trade-offs, especially those related to trustworthiness aspects and requirements. The research combines theoretical analysis with empirical studies in CPS domains such as automotive and railway, exploring how factor such as knowledge stickiness and organizational factor such as power dynamics within the organization shape the interpretation and utilization of reference architectures as boundary objects that support co-engineering practices.

The thesis makes three main contributions. First, it clarifies the theoretical understanding of boundary objects within the discourse of CPS development by situating reference architectures as socio-technical mediators of collaboration rather than merely technical design templates. Second, it offers empirical insights into how contextual factors influence the use and effectiveness of reference architectures in supporting the co-engineering in the development of trustworthy CPS. Third, it develops and evaluates an architectural framework that supports co-engineering practices by providing methods to help stakeholders navigate knowledge boundaries during the development of trustworthy CPS.

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