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Konzeption und Realisierung einer Regelung für eine torsionskompensierte Strebe

 
: Bucht, A.

Dresden, 2006, 115 pp.
Dresden, Hochschule für Technik und Wirtschaft, Dipl.-Arb., 2006
German
Thesis
Fraunhofer IWU ()
Adaptronik; adaptronic; Regelungstechnik; feedback control; Parallelkinematik; parallel kinematic machine tool; LQ-Regelung; LQ-control; aktives Strukturelement; active structure; Piezoaktor; piezoelectric actuator

Abstract
The use of lightweight elements in struts of parallel kinematic machine tools leads to unfavorable stiffness properties of the machine structure. In this case the torsional flexibility of an aluminum-made strut of the linear drive in the experimental platform 3POD is identified as a weak point. With an active structure element it is possible to increase torsional stiffness of the strut. Therefore an actuator-sensor-unit based on piezoelectric actuators is integrated in the strut. So it is possible to generate dynamic torsional moments to compensate the torsion of the strut.
Strut and actuator-sensor system are mounted in a test bench, which represent the properties of the real machine tool more simply. The dynamic behavior of the strut and the actuator-sensor-unit is described by a theoretical state-space model. With experimental measurements the validity of the theoretical model is demonstrated. Based on the established models it is possible to develop two feedback control algorithms. The first controller is developed by using methods of the frequency domain. The result is a PID-controller with an integrated low-pass filter. The synthesis of the second controller is based on time domain methods. A LQ-regulator with an additional dynamic part in the feedback is developed. With both controllers the stiffness of the strut at the first resonance frequency is significantly increased.

 

The use of lightweight elements in struts of parallel kinematic machine tools leads to unfavorable stiffness properties of the machine structure. In this case the torsional flexibility of an aluminum-made strut of the linear drive in the experimental platform 3POD is identified as a weak point. With an active structure element it is possible to increase torsional stiffness of the strut. Therefore an actuator-sensor-unit based on piezoelectric actuators is integrated in the strut. So it is possible to generate dynamic torsional moments to compensate the torsion of the strut.
Strut and actuator-sensor system are mounted in a test bench, which represent the properties of the real machine tool more simply. The dynamic behavior of the strut and the actuator-sensor-unit is described by a theoretical state-space model. With experimental measurements the validity of the theoretical model is demonstrated. Based on the established models it is possible to develop two feedback control algorithms. The first controller is developed by using methods of the frequency domain. The result is a PID-controller with an integrated low-pass filter. The synthesis of the second controller is based on time domain methods. A LQ-regulator with an additional dynamic part in the feedback is developed. With both controllers the stiffness of the strut at the first resonance frequency is significantly increased.

: http://publica.fraunhofer.de/documents/N-49464.html