Camera-based tracking system to improve the absolute accuracy of robots - OptoPose

Reference object with optical sensor i3mainz, CC BY SA 4.0

Today, robots are the most important working tool in industrial production and their characteristics have a decisive influence on productivity and quality in the manufacturing process. In terms of quality, fit issues play a particularly important role, which in turn depend on the ability to approach a specific spatial position very precisely.


High absolute positioning accuracy is necessary for production processes with varying component dimensions. Even with measuring robot systems, there are cases where the taught-in measuring points have to be changed quickly in order to react flexibly to changed product characteristics or current quality problems. After different positions of the robot have been taught, they are approached with high precision. Typically, the precision is in the range of 0.15 to 0.5 mm. Size of the robot, temperature changes and operating time further limit the accuracy. In contrast to repeatability, absolute positioning accuracy is orders of magnitude worse - typically 1 to 2 mm.

Improvements to the robot have not yet helped to increase positioning accuracy. Another promising approach is the external monitoring of the robot and the precise determination of its position in space. The “OptoPose” measuring system offers a solution for this.


The multi-camera measuring system “OptoPose” makes it possible to increase the absolute accuracy of positioning systems, usually industrial robots. A machining system or a measuring sensor can be attached to the robot head (end effector). The measuring system works with several high-resolution and calibrated measuring cameras that monitor the working space of the industrial robot. Appropriate target markings are attached to the end effector of the industrial robot as a reference object. This makes it possible to determine the position and orientation of the end effector highly accurately, reliably and quickly.

In its current configuration, the presented measuring system “OptoPose” works with four high-resolution industrial measuring cameras that monitor the reference object in a working area of 2×2×1 m³.

The position of the effector and thus the point measurement accuracy on the object can be determined to 0.1 mm at 2s. Pose determination can be performed with the current configuration at a clock rate of 1 second.


With the “OptoPose” measuring system, the previously typical weakness of industrial robots in terms of absolute accuracy is eliminated. In particular, the use of industrial measuring robots becomes much easier and more flexible. The actual positioning accuracy of the robot no longer plays a role. This means that the travel programmes can be easily changed without having to observe previous restrictions.

  • Increasing the absolute accuracy of positioning systems, e.g. industrial robots
  • Position and orientation of an end effector can be determined with high precision, quickly and reliably
  • Position determination independent of manufacturer type and positioning accuracy of the robot
  • Working range of 2×2×1 m³
  • Point measurement accuracy on the object 0.1 mm at 2sigma