# A Theoretical Foundation for Context-Aware Cyber-Physical Production Systems
###### Abstract  
The complex workflows and interactions between heterogeneous entities in Cyber-Physical Production Systems (CPPS) call for the use of context-aware computing technology to operate effectively and meet the order requirements in a timely manner. In addition to the objective to meet the order due date, due to resource contention between production processes, CPPS may enter undesirable states. In undesirable states, all or part of the production activities are in waiting states or blocked situation due to improper allocation of resources. The capability to meet the order due date and prevent the system from entering an undesirable state poses challenges in the development of context-aware computing applications for CPPS. In this study, we formulate two situation awareness problems, including a Deadline Awareness Problem and a Future States Awareness Problem to address the above issues. In our previous study, we found that Discrete Timed Petri Nets provide an effective tool to model and analyze CPPS. In this paper, we present a relevant theory to support the operation of CPPS by extending the Discrete Timed Petri Nets to lay a foundation for developing context-aware applications of CPPS with deadline awareness and future states awareness capabilities. We illustrate the theory developed in this study by an example and conduct experiments to verify the computational feasibility of the proposed method. context-aware application; cyber-physical production systems; situation-aware; deadline; discrete timed; Petri net +
Footnote †: journal: Applied  
Article  
A Theoretical Foundation for Context-Aware Cyber-Physical Production Systems  
Article  
contextual information at the point of need. Therefore, the development of context-aware applications for CPPS is an important research area in the literature [2; 3; 4]. In ICTs, context awareness is a property with which computers or applications can both sense and react based on the environment. Context awareness refers to the capability to consider the situation of entities [7]. Therefore, a context-aware application should be aware of the situation of entities in the system. Situation awareness refers to the perception of an environment and relevant events to comprehend the current situation and predict its future status [8]. CPPS aims to fulfill the order requirements by meeting the due date. However, due to the complex production processes and interactions between entities in CPPS, CPPS may enter undesirable states in which all or part of the production activities are in waiting states or blocked due to the resources not being allocated properly. Therefore, situation awareness in CPPS includes two properties: deadline awareness and future states awareness. These two situation awareness properties should be considered in the development of an effective context-aware application for CPPS. Existing studies on context-aware applications for CPS primarily focus on the generation of contextual information for entities in CPS [9]. The challenge of attaining situation awareness in CPPS is not addressed. As a result, although the real-time data are readily available to managers and workers in CPPS, managers and workers cannot respond to the environment efficiently without an effective decision support tool. As a result, managers and workers in CPPS cannot make the right decisions and perform the operations as needed in the CPPS to meet customers' order requirements. Motivated by this need, this paper attempts to develop the theory to analyze the situation of CPPS in terms of deadline awareness and future states awareness to support decision makers and generate contextual information in CPPS. The goal of this paper is to realize the situation awareness of context-aware applications for CPPS. The complexity of developing an effective context-aware application depends on the complexity of identifying the \"context\" and analyzing the \"situation\" of the entities in a system.