Exploration of two safety strategies in human-robot collaborative manufacturing using Virtual Reality

"beWare of the Robot" is a custom-designed Virtual Reality application and implemented as a platform for simulating in realtime Human-Robot collaboration in manufacturing tasks. This work reports on its use for investigating two alternative safe collaboration strategies, namely 'Reduce Speed' and 'Move Back', in the task of handling fabric when building aerospace composite material parts. Both methods are triggered when the distance of the human to the robot falls below a certain threshold. Experimentation was conducted in live tests, taking into account pressure and force thresholds regarding painful transient contact of the robot with the human following ISO/TS 15066:2016. Indices such as mean robot speed, time of collaboration, number and severity of collisions, were recorded in order to assess and 'tweak' these methods. Tweaking involved speed reduction factor in 'Reduce Speed' and waiting time after completion of stationary tasks in both strategies. Visual cues in terms of graded coloured robot motion volume to indicate varying interference of the human proved ineffective. Beyond statistical assessment of safe collaboration strategies, qualitative assessment was provided by the experiment participants according to acquired experience. (C) 2019 The Authors. Published by Elsevier B.V.