Cyber Physical Systems (CPS) are expected to shape the evolution of production towards the fourth industrial revolution named Industry 4.0. The increasing integration of manufacturing processes and the strengthening of the autonomous capabilities of manufacturing systems make investigating the role of humans a primary research objective in view of emerging social and demographic megatrends. Understanding how the employees can be better integrated to enable increased flexibility in manufacturing systems is a prerequisite to allow technological solutions, as well as humans, to harness their full potential. Humans can supervise and adjust the settings, be a source of knowledge and competences, can diagnose situations, take decisions and several other activities influencing manufacturing performances, overall providing additional degrees of freedom to the systems. This paper, studies two different integration models: Human-in-the-Loop and Human-in-the-Mesh. They are both analysed in the context of four industrial cases of deployment of cyber physical systems in production. © 2016 IEEE.