Model-based eigenfrequency analysis of a six-axis robot in workspace

In this work, model-based natural frequency analysis of a six-axis industrial robot, namely the model ABB IRB 6620, in the workspace is considered. First of all, a short review about the kinematic and dynamic equation of rigid body motion is given. Necessary relations and equations regarding relative motion are recapitulated. We then develop the kinematic and dynamic model by means of Denavit-Hartenberg algorithm and implement it into the definite robot. The next step is the implementation of the robotic model in MATLAB in order to identify natural frequencies of the robot's structure. To do so, linearization method, which was helpful to solve the non-linear equation of motion, was adopted. In order to find eigenfrequencies, a certain joint configuration within the workspace is applied for a four-axis robot in case of rigid joints and links. Afterwards, we improve simulation results by extension of the existing model regarding joint stiffness, elastic deformation of the robotic arm parts. Finally, we step forward to investigate eigenfrequencies of the robot within its workspace for both rigid case and joints' stiffness and damping case.