Ultrafast and Robust, Resettable Threshold Sensors Based on Discontinuity-Induced Nonlinearities

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Threshold sensors are input-output devices that switch operating state in reaction to the crossing of a threshold value of their input. These are used to monitor and control critical values of temperature, voltage, pressure, etc. in both consumer and industrial settings. The change in operating state might be permanent, such as when a fuse burns out, or capable of being reset, such as with a circuit breaker. This research effort aims to analyze, design, fabricate, and experimentally characterize a class of ultrafast and robust, resettable electromechanical threshold sensors. The fundamental design principle proposed here relies on predicted changes in system response particular to piecewise-smooth dynamical systems including impact- and friction-like discontinuities. The proposed research will validate these theoretical predictions and demonstrate the successful regulation of switch rates using active feedback control in macro- and microscale electromechanical devices.This research effort makes original contributions to a nascent effort in nonlinear dynamics that will transform the field from a tool for modeling and analysis of observed behavior to a tool of intentional synthesis of engineered systems. The engineering of man-made devices to exhibit desirable nonlinearities has the potential to dramatically broaden the toolbox of the applied engineer and to change the performance characteristics in existing applications by orders of magnitude. The present work is a basic and comprehensive effort to establish the so-called nonsmooth fold bifurcation associated with the onset of low-velocity contact in vibro-impacting systems as an exploitable nonlinear phenomenon in device design, e.g., capacitively-driven circuit protection devices. Preliminary results on the ultrafast response following this bifurcation show a significant potential for dramatic improvement in sensor performance.This research is an international collaboration with research groups at the Royal Institute of Technology in Stockholm, Sweden and at La Sapienza University in Rome, Italy and will include several extended visits of project graduate research assistants to the international sites.