Modellierung und Validierung der Krafterzeugung mit Stick-Slip-Antrieben für nanorobotische Anwendungen

Piezo-actuated miniaturized Stick-Slip drives (positioners) are well known both in research and industry. The function of the drives can be subdivided into the phase of actuation (Stick) and the retraction of the actuator (Slip). Although the deflection of the actuator is limited, theoretically infinite motion can be realized, combined with high positioning resolution. In this work a new method is investigated and characterized to use Stick-Slip drives not only for positioning purposes, but also for generation of well-defined forces. The method is based on the properties of the Stick-Slip friction, which is signified by the interaction of surface asperities. It allows generation of virtually arbitrary forces. The amount of force is defined by the drive’s preload, the control signal’s amplitude and the Stick-Slip contact conditions. Moreover, the force can be controlled externally using the excitation signal. The method is not in a need of any sensor and thus it inhibits a great application potential. Friction between actuator and output plays a key role for understanding the drive and therefore the force generation process. Friction is a complex matter and can be modeled only approximative with simple models. A new friction model as result of this work is designed in such a way that all relevant parameters including the generated force can be represented. Additionally, some aspects are specially investigated, so the dependency of the forces on material conditions. The process of establishing the model is supported by simulations, which are justified permanently by measurements. Validation is done with focus on two application-oriented scenarios. On the one hand the method is transferred to a robot exhibiting several degrees of freedom to generate arbitrary, vectorial forces in three dimensions. This can be of interest for metrology tasks of complex geometrical structures. On the other hand the generation of notably small forces is aimed for to demonstrate the exploitation of the microand nanoscale.