Robot Machining


Dynamics modeling for model-based feedforward control

Photo of a robot from Mabi © Lukas Gründel  

The topic of Robot Machining has been researched at the WZL of RWTH Aachen for several years now. A large workspace, high flexibility and significantly lower investment costs are decisive advantages of industrial robots (IR), leading to the development of more and more application scenarios in industry during the recent years. Now that IR can also be controlled with numerical controls and programmed via standard G-code, the disadvantages of a non-consistent CAD-CAM-NC toolchain are no longer an issue. However, the critical disadvantage of IR compared to machine tools is still the pose-dependent and comparatively low stiffness. The demonstrator shown here was put into operation at the WZL of RWTH Aachen for developingcontrol methods to compensate the displacements due to the induced process forces. The robot Mabi MAX100 from Mabi Robotic AG is equipped with a direct encoder in each axis and is controlled by the NC Sinumerik 840D sl from Siemens AG. The current focus of research is the dynamics modeling of the robot for model-based fast-forward control in order to enable a prediction of the dynamic behavior during the process and thus an optimization of the machining accuracy. Particular focus is placed on the identification of inertia parameters such as masses, center of gravity coordinates and the entries of the inertia tensors.