Force Controlled Piezoelectric Fiber Press
Moreno Ordonez, Antonio (2012)
Moreno Ordonez, Antonio
2012
Automaatio-, kone- ja materiaalitekniikan tiedekunta - Faculty of Automation, Mechanical and Materials Engineering
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Hyväksymispäivämäärä
2012-10-03
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201210051307
https://urn.fi/URN:NBN:fi:tty-201210051307
Tiivistelmä
The study of the properties of paper in in the micro scale requires the use of devices on the same dimensional order. Paper fiber bonds, the construction unit of paper sheets, can be manufactured, manipulated and tested thanks to a variety of micro actuators. In the manufacturing process of paper fiber bonds, a tool able to press the fibers together is paramount, along with a force control scheme that can guarantee an acceptable performance from the actuator in question.
This thesis proposes an open-loop force control technique for a piezoelectric stack actuator, consisting of the compensation of the hysteresis and creep nonlinearities and vibrations. The hysteresis compensation is based on model inversion, resorting to the Prandtl-Ishlinskii method for modeling static hysteresis. Creep compensation, on the other hand, consists of an inverse multiplicative structure, meaning that no model inversion is required and therefore simplifying the process. Last, vibration is dealt with by means of an input shaping technique.
The thesis starts with a literature study, followed by the discussion of the method to be implemented and the selection of the required software and hardware for the experiments, as well as the design of a custom-built test platform. The second half of the thesis begins with the characterization of the actuator and tackles the design and implementation of the control.
The experimental results show that an open-loop control scheme is possible for force control of a piezoelectric actuator and proves its efficiency and convenience for micromanipulation tasks: hysteresis is reduced to less than 3 %, creep is kept under 1 % and overshoot is decreased to less than 10 % at low inputs and apparently eliminated at higher inputs. Also, the results suggest that this method can easily be extended to other types of actuators and applications, albeit certain additional issues might have to be taken into consideration.
This thesis proposes an open-loop force control technique for a piezoelectric stack actuator, consisting of the compensation of the hysteresis and creep nonlinearities and vibrations. The hysteresis compensation is based on model inversion, resorting to the Prandtl-Ishlinskii method for modeling static hysteresis. Creep compensation, on the other hand, consists of an inverse multiplicative structure, meaning that no model inversion is required and therefore simplifying the process. Last, vibration is dealt with by means of an input shaping technique.
The thesis starts with a literature study, followed by the discussion of the method to be implemented and the selection of the required software and hardware for the experiments, as well as the design of a custom-built test platform. The second half of the thesis begins with the characterization of the actuator and tackles the design and implementation of the control.
The experimental results show that an open-loop control scheme is possible for force control of a piezoelectric actuator and proves its efficiency and convenience for micromanipulation tasks: hysteresis is reduced to less than 3 %, creep is kept under 1 % and overshoot is decreased to less than 10 % at low inputs and apparently eliminated at higher inputs. Also, the results suggest that this method can easily be extended to other types of actuators and applications, albeit certain additional issues might have to be taken into consideration.