Worst case braking trajectories for robotic motion simulators

Abstract

Motion simulators based on industrial robots can produce high dynamic accelerations and velocities compared to classical hydraulic hexapod systems. In case of emergency stops, large and possibly harmful accelerations can occur. This paper aims to provide an optimization procedure to generate worst case trajectories in order to test for these harmful accelerations, by maximizing the kinetic energy prior the emergency stop. The dynamical and mechanical limits of the robot are considered as constraints of the optimization criterion. An exemplary worst case trajectory is simulated using a braking model and the resulting Head Injury Criterion (HIC) is calculated and compared with older tests, using non-optimized trajectories. A significant higher, yet with the current robot dynamics not harmful HIC value can be generated.