Human-Robot Collaborative Assembly in Smart Manufacturing Environments: Safety Performance, Cycle Time Optimisation, and Ergonomic Assessment Across Three Cobot Platforms

Abstract

The integration of collaborative robots (cobots) into human- occupied assembly workstations represents one of the most significant developments in contemporary manufacturing automation. This study presents a controlled experimental investigation of human- robot collaborative (HRC) assembly performance across three commercially deployed cobot platforms: Universal Robots UR10e, KUKA LBR iiwa 14, and FANUC CR- 35iA, evaluated against manual assembly baselines across six representative automotive sub- assembly tasks. A total of 2,700 assembly trials were conducted under standardised conditions replicating production line constraints, with ISO/TS 15066:2016 safety zone monitoring throughout. Results indicate that HRC configurations reduced mean cycle times by 18.3 to 24.7% relative to manual benchmarks. All three cobot platforms achieved ISO/TS 15066 force- speed compliance in 98.7 to 99.6% of measured interactions. Ergonomic assessment using RULA (Rapid Upper Limb Assessment) revealed a 41.2% reduction in ergonomic risk scores for the most physically demanding tasks. Economic analysis projects an annual quality cost saving of USD 312,000 per production line with a payback period of 14.8 months at full deployment scale.