###### Abstract  
Collaborative robots are revolutionising the manufacturing industry and the way workers perform their tasks. When designing shared workspaces between robots and humans, human factors and ergonomics are often overlooked. This study assessed the relationship between cognitive workload, workstation design, user acceptance and trust in collaborative robots. We combined subjective and objective data to evaluate the cognitive workload during an assembly task in three different scenarios in which we manipulated various features of the workstation and interaction modalities. Our results showed that participants experienced a reduction in cognitive workload in each of the three trials, indicating an improvement in cognitive performance. Additionally, we found that user acceptance predicted perceived stress across the trials but did not significantly impact the cognitive workload. Trust was not found to moderate the relationship between cognitive workload and perceived stress. This study has the potential to make a significant contribution to the field of collaborative assembly systems by providing valuable insights and helping to bridge the gap between researchers and practitioners. This study can potentially impact companies looking to improve safety, productivity and efficiency.  
human-robot collaboration; cognitive workload; technology acceptance; trust; workstation +
Footnote †: journal: Applied sciences  
13 December 2022  
collaboration; together with usability and trust towards the robot, acceptance is highlighted as fundamental for optimal and reliable interaction [13; 14; 15].  
Many organisations addressed the importance of human factors and ergonomics (HFE) in HRC. The role of HFE involves studying the ergonomics of human-robot interfaces, developing guidelines and standards for HRC, and conducting evaluations and assessments of human-robot systems. By considering the human factors and ergonomic aspects in the design process, the collaboration between humans and robots could be more effective, efficient and safe [16; 17; 18]. In recent years, there was an increasing number of studies in HRC that examined how to ensure an adequate level of safety in the shared workplace by reducing context-related risks, such as distrust towards automation, stress and cognitive overload [19; 20; 21], that could lead to cognitive failures. In addition, these cognitive ergonomics variables can also influence each other and exponentially increase safety risks for workers. For instance, low levels of trust are associated with a higher cognitive workload [22], which increases stress levels [23].  
Based on the findings presented in the literature, the authors developed a set of integrative and human-centred design principles for the appropriate integration of cognitive ergonomics in collaborative assembly systems (CAS) [24]. This study followed on from the work of [24], which specifically investigated how the main variables of cognitive ergonomics (i.e., cognitive workload, acceptance, trust and perceived stress) are influenced by different features of industrial collaborative workstations and interaction patterns. The present work focused on cognitive workload and investigated its relationship with workstation design, user acceptance and trust in collaborative robots. In particular, the present study aimed to enrich the theoretical models by examining the role of acceptance in predicting cognitive workload and perceived stress and the role of trust in moderating the relationship between cognitive workload and stress.