Modelling of Mechanical Flexibilities in Robotic Manipulators and Evaluation of Their Impact on Motion Performance

Sammanfattning: In order to achieve the best robot performance, the exibilities in the mechanical structures of a robot manipulator needs to be modelled and compensated for, when designing a controller. By examining how each flexible component contribute to the overall dynamic performance, the robot's mechanical design can be altered to optimised performance and minimise cost. In this report, mechanical properties of gearboxes and links are investigated andtheir impact on robot performance examined. Different modelling approaches are presented for these components. A nite-element model of the link arm is reduced by using the Craig-Bampton method. Torsional exibility and hysteresis of the gearboxes are modelled using a differential equation in combination with a polynomial. The models are implemented and evaluated in the simulation environment Dymola. An integration of complete robot models with aproprietary controller is done using FMI. The controller later controls the robotmodels and the results are compared with real robot measurements. Attempts to model the robotic link using the Craig-Bampton model prove unsuccessful due to software issues. Results from modelling the gearbox suggest that hysteresis has a negligible impact on the robot's precision. Also, the hysteresis in this model is cancelled out by oscillations in the gearbox that occursdue to high accelerations when the manipulator moves.