Compact optical system for projection of dynamic safety patterns in cobot workspaces

With rapid factory automation, it is increasingly prevalent that humans and robots cooperate and share the same workplace. This necessitates robust safety measures such as visible dynamic indication of the working area of the robot to alert the human operator. For such purpose projection display systems can be used, however their typical dimensions may be too bulky and costs too high for widespread use. We propose a design of a low-cost compact optical system based on a pixelated white LED source for projection of the dynamic “safety borders” around the robotic arm, which are continuously recognized by the automatic machine-vision based control system and visualized for human workers in real time. The main challenges for the optics layout are achieving a low F/# for large projected flux together with a large projected field of view (FOV) but maintaining low manufacturing cost. The developed optical system consists of two lenses including a custom-made asphere and provides ±18.5° FOV with sufficient feature sharpness for stable recognition.