Over the past several years Eastman Kodak Company has been developing technologies in the area of active vibration control for space structures. The basic goal is to keep the structure as still as possible during operation using active and/or passive damping and isolation. Inherent in these space structures are many of the qualities that make a system difficult to actively control. They are lightly damped, modally dense, and are sensitive to weight increases, as well as thermal loads that a powered actuator might apply to the structure. Further, any system must be fully space qualifiable. To overcome these hurdles, Kodak has investigated several schemes to apply in a multitier approach to achieve maximum benefit from an active system. This paper will present the theory of operation and test results for one of these technologies called `Self-Sensing Active Vibration Elimination'. We will elaborate on a collocated active damping technique using self-sensing piezo-ceramics. The term `self-sensing' is used to describe the phenomenon of simultaneous actuation and sensing using the same device, in this case piezo- ceramic wafers. This work is an extension of Dosch et al. (1992). The key differences lie in the geometry in which the self-sensor must operate. We parallel the theoretical development given in Dosch et al., but present the development in more of a tutorial form. Research in this area is plentiful, however, less than desirable results have often been reported on systems more complex than a cantilever beam. A strain-rate self-sensor with > 60 dB dynamic range and nano-strain sensitivity in the 10 to 200 Hz frequency band is detailed below, proving that self-sensing can be made to work on large structures. Closed loop results are presented that show performance improvements of over 30 dB reductions in the structural resonance response. It should be mentioned that the system described below could easily be applied to extremely small systems (such as a disk drive read/write arm). The self-sensor would allow an entire controller to be placed on a single 14-pin DIP chip, and since the actuator is also the sensor, less instrumentation loading will occur.

Date Published: 8 May 1995
PDF: 13 pages
Proc. SPIE 2443, Smart Structures and Materials 1995: Smart Structures and Integrated Systems, (8 May 1995); doi: 10.1117/12.208302

Published in SPIE Proceedings Vol. 2443:
Smart Structures and Materials 1995: Smart Structures and Integrated Systems
Inderjit Chopra, Editor(s)