16. Modal Analysis of a 7 DoF Sweet Pepper Harvesting Robot

Modal Analysis is a well-established key tool used to analyze the dynamic behavior of a structure. A robot manipulator consists of mechanical structures, like the body links between the joints and gears, and mechatronic components, like motors and their control system. The dynamic behavior of all subcomponents making up the robot arm are individually well understood. However, their respective influence on the dynamic behavior of the entire robot system is still a matter of research. Understanding the dynamics of the manipulator and setting up a validated model of its full dynamics is essential, in order to devise proper control strategies. One specific challenge comes from the fact that the vibration properties (modes, damping and frequencies) depend on the overall pose and thus change during the operation of the robot. Further, non-linearities from the joints and the action of the joint controller can significantly influence the dynamics of the system. In this paper, the influence of these effects on the overall dynamic behavior of a 7 DOF robot manipulator developed for automated sweet pepper harvesting is analyzed, using Modal Analysis.