Evaluation of joystick built-in emergency stop function for mobile elevating work platform safety and human factors and ergonomics in accident prevention

A mixed reality simulation study evaluated human factors, ergonomics and safety of an additional safeguard for the prevention of mobile elevating work platform (MEWP) accidents while at the same time enabling unhindered MEWP task performance. The simulation environment consisted of a real MEWP work platform, real controls combined with virtual MEWP chassis and telescopic beam in an industrial hall for performing on-site navigation and inspection tasks. Mental workload as reflected in task performance and ratings from 22 naïve and experienced MEWP operators was investigated for 3 hrs each while controlling the MEWP by joysticks with built-in supplemental emergency stop function and release force of either 14 or 36 N. Task performance resulted in several virtual collisions of the MEWP operator and the MEWP with obstacles in the environment and the MEWP surpassing floor markings, however, without triggering the emergency stop function. Instead, a release force of 14 N as compared to 36 N resulted in significantly more actuations happening only inadvertently and during hazard-free navigation sequences. In addition, the joysticks order of system control dynamic was configured as a velocity control for operational reasons and raised serious concerns for use in combination with the stop function in hazardous situations due to increasing risk of severe injuries. According to the results of the evaluation study, the safeguard design as investigated is not recommended for accident prevention. The study provides information for safeguard development and future evaluations.

Practical Relevance

This empirical investigation contributes to state-of-the-art of science and technology and provides scientific evidence from human factors and ergonomics to be used for design and selection of effective safety devices in occupational safety and health.