Space-time extension of the projection and camera-based technology dealing with high-frequency light interference in HRC applications

Optical sensor systems are widely used in academic and research with the aim of providing safety of humans at human-robot collaboration (HRC). For using these mainly 2D- or 3D- cameras as speed and separation monitoring systems in industrial HRC settings several requirements need to be fulfilled. Beside the overall functional safety of the sensor, the monitoring system have to deal with changing environmental influences as well. This includes not only natural illumination changes of ambient light (sunlight) but also high frequency pulsation of flashlights (stroboscopic effects). In recent years, an innovative optical sensor system based on camera and projector techniques was introduced. The implemented working principle of this HRC monitoring system offers high potential to meet the requirements of current safety standards. In this paper, we present the extension of the pulse-modulated light principle to a space-time approach that is capable of handling sudden illumination changes (e.g. flashlights) without falling to danger.