  With 3D sensing becoming cheaper, environment-aware and visually-guided robot
arms capable of safely working in collaboration with humans will become common.
However, a reliable calibration is needed, both for camera internal
calibration, as well as Eye-to-Hand calibration, to make sure the whole system
functions correctly. We present a framework, using a novel combination of well
proven methods, allowing a quick automatic calibration for the integration of
systems consisting of the robot and a varying number of 3D cameras by using a
standard checkerboard calibration grid. Our approach allows a quick
camera-to-robot recalibration after any changes to the setup, for example when
cameras or robot have been repositioned. Modular design of the system ensures
flexibility regarding a number of sensors used as well as different hardware
choices. The framework has been proven to work by practical experiments to
analyze the quality of the calibration versus the number of positions of the
checkerboard used for each of the calibration procedures.
