This Faculty Early Career Development (CAREER) research program will use concepts from modern control theory to answer fundamental questions regarding the optimal transduction and management of energy in a broad class of electromechanical vibratory systems, including (i) Floating structures to harvest utility-scale power from ocean waves, (ii) Civil structures with self-powered actuation networks to redistribute and dissipate vibration energy during seismic events, and (iii) Distributed piezoelectric transducers to scavenge ambient vibration energy for wireless sensing applications. These systems exhibit certain core similarities which permit their analysis in a unified control-theoretic framework. They are all distributed control problems in which harvested energy, structural deformation, and power flow must be balanced in a stochastic setting. This research will characterize the manner in which the nonlinear power flow constraints inherent in the electronics of such systems restrict their ability to be controlled. This characterization of control feasibility will in turn be used to create a generalized multi-objective optimal control synthesis for these systems, which is analytically tractable, yet versatile enough to handle the variety of design goals and circumstances which may arise in different applications. The research conducted here will encompass both linear and nonlinear controller design methods, and will also investigate the concurrent optimization of the control, electronic, and structural subsystems. Experimental validation these concepts will be conducted, in the context of the three examples listed above, in conjunction with collaborators at Duke and UCSD.
Results from this research will have implications in a wide array of control applications where energy is important, and the experimental focus is aimed at problems of great relevance to contemporary society. Ocean wave energy is a valuable, untapped, renewable resource, and the technology for its conversion is still emerging. This research will determine the manner in which to control power generation from a floating wave energy converter, to optimize its ability to produce useful energy. Meanwhile, the research conducted in self-powered systems for seismic risk reduction and wireless damage detection address two of the ?grand challenges? facing modern structural engineers. Most of the recent innovation in these areas has focused on device design, and results from this research will be used to determine the optimal control of these devices to maximize their ability to extract useful energy from a vibrating structure. Through coordination with a new Energy Certificate being implemented at Duke, the wave energy experimental program will serve as the focal point for multidisciplinary interaction between undergraduate students in Mechanical, Civil, and Electrical Engineering, as well as the School of the Environment. Additionally, this project will leverage the success of Duke?s outreach programs to provide research opportunities not only to students at Duke, but also to undergraduates from underrepresented demographics, studying elsewhere in the greater North Carolina region.