Analytical Study of Human Robot Collaboration Ergonomics and Safety Performance in a Nigerian Manufacturing Pilot Cell

Human robot collaboration, in which industrial cobots and human workers share a workspace to perform complementary assembly tasks, represents an emerging production paradigm with significant potential for Nigerian manufacturing contexts where full automation is economically infeasible. This study presents an analytical investigation of ergonomic performance and safety outcomes in a pilot HRC cell established at an electronics assembly facility in Ogun State, South West Nigeria. A Universal Robots UR5e collaborative robot was deployed alongside human operators for a circuit board component insertion task, with the cobot performing repetitive screw-fastening while operators handled component placement requiring dexterity beyond the robot's current capability. Ergonomic assessment of the human operators was conducted using the Rapid Upper Limb Assessment and OWAS posture analysis methods before and after HRC deployment. Safety performance was monitored through ISO/TS 15066-compliant speed and separation monitoring implemented via a 3D time-of-flight camera system. Operator musculoskeletal discomfort ratings showed statistically significant reductions following HRC deployment, particularly in shoulder, neck, and wrist discomfort scores associated with the eliminated repetitive screwing tasks. Throughput improved by 19 percent compared to the fully manual baseline cell. Operator trust and acceptance of the collaborative robot was assessed through a validated Human-Robot Interaction questionnaire at two-week and eight-week intervals, showing a statistically significant improvement in trust scores between assessments. The study documents the most significant HRC integration challenges encountered in the Nigerian factory context and provides design recommendations for safe and ergonomically effective HRC cell layouts. Keywords: human-robot collaboration, ergonomics, cobot, manufacturing safety, Ogun State