Cyber-Physical Systems (CPS) integrate computation, networking and physical processes to produce products that are autonomous, intelligent, connected and collaborative. Resulting Cyber-Physical Systems of Systems (CPSoS) have unprecedented capabilities but also unprecedented corresponding technological complexity. This paper aims to improve understanding, awareness and methods to deal with the increasing complexity by calling for the establishment of new foundations, knowledge and methodologies. We describe causes and effects of complexity, both in general and specific to CPS, consider the evolution of complexity, and identify limitations of current methodologies and organizations for dealing with future CPS. The lack of a systematic treatment of uncertain complex environments and “composability”, i.e., to integrate components of a CPS without negative side effects, represent overarching limitations of existing methodologies. Dealing with future CPSoS requires: (i) increased awareness of complexity, its impact and best practices for how to deal with it, (ii) research to establish new knowledge, methods and tools for CPS engineering, and (iii) research into organizational approaches and processes to adopt new methodologies and permit efficient collaboration within and across large teams of humans supported by increasingly automated computer aided engineering systems.

Design of complex systems requires collaborative teams to overcome limitations of individuals; however, teamwork contributes new sources of complexity related to information exchange among members. This paper formulates a human subjects experiment to quantify the relative contribution of technical and social sources of complexity to design effort using a surrogate task based on a parameter design problem. Ten groups of 3 subjects each perform 42 design tasks with variable problem size and coupling (technical complexity) and team size (social complexity) to measure completion time (design effort). Results of a two-level regression model replicate past work to show completion time grows geometrically with problem size for highly coupled tasks. New findings show the effect of team size is independent from problem size for both coupled and uncoupled tasks considered in this study. Collaboration contributes a large fraction of total effort, and it increases with team size: about 50–60 % of time and 70–80 % of cost for pairs and 60–80 % of time and 90 % of cost for triads. Conclusions identify a role for improved design methods and tools to anticipate and overcome the high cost of collaboration.

Design methods for federated systems must consider local incentives and interactive effects among independent decision-makers. This paper extends value-centric design methodology to multi-actor cases by using game-theoretic principles. Federated systems are represented as a Stag Hunt game where players choose between independent (noncooperative) and federated (cooperative) strategies. Risk arises from the possibility of withdrawn cooperation and can be quantitatively assessed for particular design alternatives with subjective estimates of the probability for cooperation and objective measures such as the weighted average log measure of risk. The value of cooperation can be bounded below by designing for the independent strategy and above by designing for a centralized strategy controlled by a single authority. An application case considers a stylized system value model of a distributed satellite system with two players and symmetric design decisions. Results demonstrate lower and upper bounds to the value of a federated strategy with opportunistic, fixed-cost communication services. Quantitative risk analysis shows the value-maximizing federated design under mutual cooperation carries risk which can be mitigated by more conservative design alternatives with only minor loss of value.

This paper develops a flexibility management framework for space logistics mission planning under uncertainty through decision rules and multistage stochastic programming. It aims to add built-in f...