Adaptive Impedance Control Using Piezoelectric Honeycomb Actuator Concepts

Kurzfassung

A theoretical, numerical, and experimental investigation is described in which an impedance based method has been used to improve the performance of actuator systems. Active vibration control of mechanical structures can be achieved by implementing or attaching multifunctional actuator elements with properly chosen mechanical input impedances. Depending on the particular requirements, the adaptronic system may be designed, for example, •to compensate local vibrations (“infinite impedance”), •to absorb the maximum possible power from the structures (“matched impedance”), •to add a locally acting mass and/or stiffness (“reactive impedance”), •or even to compensate an existing mass or stiffness by adding a “negative mass” or “negative stiffness”, a feature beyond the possibilities of conventional passive systems. Many research projects in adaptronics have been shown that there is a big challenge to develop adaptronic systems that should fulfil contradictory requirements such as •low energy in the presence of high mechanical loads, •high static stiffness in opposite to large dynamic deflections, •high sophisticated components but low cost. The success of industrial adaptronic products increasingly depends on the possibility to realize smart structural components that are lightweight and low energy systems but have high powerful performance. Therefore this investigation firstly theoretically describes which impedance relationships must be present for high efficiency degrees. This power or impedance matching process consequently causes to actuator systems that are not anymore independent from frequency. Now they show dynamic eigenproperties as a result of the illustrated energy based optimization. An illustrative low energy actuator concept will be presented. It contains hexagonal cells such as honeycombs that considers piezoelectric materials. The main advantages of this novel actuator type are: •high stiffness in lower frequency range, •structural conform to the system to be controlled (matched mechanical properties), •useful as actuator and sensor, •reduced electrical power consumption, •lightweight construction with nearly perfect load distribution, •multiple functions, such as interfaces for translatory motions and joints for torsional movements. Numerical and experimental results will demonstrate the interesting mechanical and electrical actuator properties.