Influence of Servo Characteristics on Motion Accuracy of Parallel Kinematic Mechanism
Parallel kinematic mechanism (PKM) is applied to machine tools and robots since its flexibility and speed. In machine tools, additionally, motion accuracy is strongly desired. Although various research works aimed to calibrate static geometrical deviations of the PKM machines in order to improve motion accuracy, influence of dynamic motion error of servo system has not been investigated well up to now. In this study, the influence of servo characteristics on motion accuracy of a PKM machine tool driven by six servo motors is discussed, because it is expected that the contouring motion accuracy of a PKM machine tool is strongly depends on the servo characteristics. A servo motor which installed to the machine is modeled to simulate the motion characteristics of each servo motor. The motor models are coupled with a model of link mechanism, and the motion accuracy of a tool center point is simulated. Also, both of positional and angular errors are simulated successfully. As the results of the simulations, it is clarified that the motion accuracy is strongly depends on the servo characteristics and location of the tool center point. In addition, the motion errors are observed as six dimensional errors. It is also discussed that the influence of friction torques on the motion accuracy.
Tojiro Aoyama, Hideki Aoyama, Atsushi Matsubara, Hayato Yoshioka and Libo Zhou
R. Sato et al., "Influence of Servo Characteristics on Motion Accuracy of Parallel Kinematic Mechanism", Key Engineering Materials, Vols. 523-524, pp. 762-767, 2012