Where am I? Robots also have to answer this question while they are gluing, welding or grouting workpieces. This is because the end result is only precise if the robot controller knows exactly where the gluing or welding head is located down to the millimeter. The robot therefore needs a visual aid.

This is usually done by special sensors, most of which work on the principle of laser triangulation: A laser diode throws a line of red light onto the workpiece, from where the light is reflected at a certain angle and thrown further into a camera. The position from which the light hits the camera chip can be used to determine the position and distance of the sensor to the workpiece within the coordinate system.

However, the existing sensors are limited in their flexibility due to shadowing. With conventional sensors, height measurement only works if they are mounted in the machining direction. If the direction of movement of the robot changes with these sensors, the eye remains blind. The only alternatives are to use multiple sensors or additional axes.

Cover everything with the measuring curtain

Researchers at the Fraunhofer Research Institution for Additive Production Technologies (IAPT) in Hamburg have now developed an alternative: The sensor called 'SensePRO' is compact at 15 centimeters in diameter, has a specially developed evaluation sensor system that enables a shadow-free all-round view, and generates a 360-degree measuring curtain that offers more flexibility in the direction of measurement. No matter where the robot moves, at least one laser line is always optimally positioned and delivers precise position information to the camera.

In addition, there is no shadowing of the light by complicatedly shaped components. This measuring principle is now patented. The user can use the sensor without any integration effort for all robot systems, completely flexibly and above all reliably in gluing and welding processes and achieve simplified process control and quality assurance.

In order to be able to work in harsh production environments for long periods of time, the sensor contains a cooling module that works with either water or air. For this purpose, the optical bench on which the laser diodes and cameras are mounted has an internal cooling structure. The sensor is designed to fit on robots from all common manufacturers, from Kuka to Fanuc, and is suitable for all conceivable application scenarios. This allows easy integration into existing production systems. SensePRO is expected to be ready for series production in 2021.