@article{naik_vermillion_2024, title={Integrated physical design, control design, and site selection for an underwater energy-harvesting kite system}, volume={220}, ISSN={["1879-0682"]}, DOI={10.1016/j.renene.2023.119687}, abstractNote={This paper presents a co-design framework that optimizes the kite design, site, and controller of a kite-based marine hydrokinetic (MHK) energy-harvesting system. The formulation seeks to maximize a techno-economic metric, namely power-to-mass ratio, by simultaneously considering three key categories of decision variables while accounting for the coupling between the three. The simultaneous consideration presents computational challenges associated with optimizing a large number of decision variables, a subset of which (control variables) are time trajectories. The multi-fidelity co-design formulation presented in this work utilizes two techniques, namely nesting and layering, to solve the optimization problem in a computationally tractable manner without significantly compromising on accuracy. Specifically, nesting allows for efficient integration of the three optimization sub-modules into one integrated framework without accuracy losses, whereas layering allows for successive design space reduction as the overall optimization progresses from using a low-fidelity model to using a higher-fidelity model. The resulting integrated co-design tool was applied to a region of interest off the North Carolina coast to optimally choose a combination of deployment site, kite design, and control strategy. We show that the integrated co-design tool results in a two-fold performance improvement over benchmarks derived from sequential (or independent) optimization of the kite categories, thereby underscoring the need for co-design. Computational effectiveness is demonstrated by comparing the computational cost of the nested and layered approach against the estimated computational costs that would be required to perform a single high-fidelity integrated optimization over the entire design space.}, journal={RENEWABLE ENERGY}, author={Naik, Kartik and Vermillion, Chris}, year={2024}, month={Jan} }
 @article{naik_beknalkar_reed_mazzoleni_fathy_vermillion_2023, title={Pareto Optimal and Dual-Objective Geometric and Structural Design of an Underwater Kite for Closed-Loop Flight Performance}, volume={145}, ISSN={["1528-9028"]}, DOI={10.1115/1.4055978}, abstractNote={Abstract}, number={1}, journal={JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME}, author={Naik, Kartik and Beknalkar, Sumedh and Reed, James and Mazzoleni, Andre and Fathy, Hosam and Vermillion, Chris}, year={2023}, month={Jan} }
 @article{reed_abney_mishra_naik_perkins_vermillion_2023, title={Stability and Performance of an Undersea Kite Operating in a Turbulent Flow Field}, volume={31}, ISSN={["1558-0865"]}, DOI={10.1109/TCST.2023.3237614}, abstractNote={In this article, we examine the effects of flow disturbances resulting from turbulence on the dynamic behavior of an underwater energy-harvesting kite system that executes periodic figure-8 flight. Due to the periodic nature of the kite’s operation, we begin by assessing orbital stability using the Floquet analysis and stroboscopic intersection analysis of a Poincaré section, with the former analysis performed on a simplified “unifoil” model and the latter performed on a six-degree-of-freedom (6-DOF)/flexible tether model. With periodic stability established, a frequency-domain analysis based on a linearization about the kite’s path is used to predict the quality of flight path tracking as a function of the turbulence frequency. To validate the accuracy of these simulation-based predictions under flow disturbances, we compare the predictions of the kite’s behavior against the results of small-scale tow testing experiments performed in a controlled pool environment.}, number={4}, journal={IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY}, author={Reed, James and Abney, Andrew and Mishra, Kirti D. and Naik, Kartik and Perkins, Edmon and Vermillion, Chris}, year={2023}, month={Jul}, pages={1663–1678} }
 @article{abney_reed_naik_bryant_herbert_leonard_vadlamannati_mook_beknalkar_alvarez_et al._2022, title={Autonomous Closed-Loop Experimental Characterization and Dynamic Model Validation of a Scaled Underwater Kite}, volume={144}, ISSN={["1528-9028"]}, DOI={10.1115/1.4054141}, abstractNote={Abstract}, number={7}, journal={JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME}, author={Abney, Andrew and Reed, James and Naik, Kartik and Bryant, Samuel and Herbert, Dillon and Leonard, Zak and Vadlamannati, Ashwin and Mook, Mariah and Beknalkar, Sumedh and Alvarez, Miguel and et al.}, year={2022}, month={Jul} }
 @article{beknalkar_naik_vermillion_mazzoleni_2022, title={Closed-Loop-Flight-Based Combined Geometric and Structural Wing Design Optimization Framework for a Marine Hydrokinetic Energy Kite}, ISBN={["978-1-6654-6809-1"]}, ISSN={["0197-7385"]}, DOI={10.1109/OCEANS47191.2022.9977369}, abstractNote={A marine hydrokinetic (MHK) kite offers an economical solution to the challenges of size and investment costs posed by the existing class of energy converters used to harvest tidal and ocean current energy. MHK kite systems are complicated devices that harvest ocean current energy by flying a tethered kite perpendicular to the motion of the current flow. They possess strong coupling between closed-loop flight control, geometric design, and structural design and hence it is important to consider all three facets simultaneously while designing a MHK kite system. Our previous work addressed this problem of simultaneous optimization of plant and controller through a control-aware optimization framework that fuses a geometric optimization tool, a structural optimization tool, and a closed-loop flight efficiency map. While our previous work analyzed the effect of key wing geometric parameters (wingspan and aspect ratio) on the performance of MHK kite systems, the present work represents the next crucial step in the study of ocean energy-harvesting kite systems and expands the design space to include several other wing geometric parameters - airfoil design, wing taper, wing twist, and dihedral angle. The effect of these decision variables on the power-to-mass ratio is estimated through an optimization framework based on a sequential approach. First, using sensitivity analysis, the framework determines which design variables in the design space affect the peak mechanical power generated while flying a cross-current path. In the next step, the combined geometric and structural optimization tool derives optimal values of variables in the reduced design space that results in a minimum structural mass. The constraints in the optimization problem include a lower limit on the peak power and limits on the number and dimensions of I-beam spars and the thickness of the wing shell. With a wing structure that can sustain peak lifting loads equal to less than a fixed value, the rest of the design variables are optimized to achieve maximum time-averaged power using medium-fidelity closed-loop-flight-based simulations. The final results of the optimization framework include an optimized wing geometry and wing structure with a maximized power-to-mass ratio for an MHK kite.}, journal={2022 OCEANS HAMPTON ROADS}, author={Beknalkar, Sumedh and Naik, Kartik and Vermillion, Chris and Mazzoleni, Andre}, year={2022} }
 @article{siddiqui_naik_cobb_granlund_vermillion_2020, title={Lab-Scale, Closed-Loop Experimental Characterization, Model Refinement, and Validation of a Hydrokinetic Energy-Harvesting Ocean Kite}, volume={142}, ISSN={["1528-9028"]}, DOI={10.1115/1.4047825}, abstractNote={Abstract}, number={11}, journal={JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME}, author={Siddiqui, Ayaz and Naik, Kartik and Cobb, Mitchell and Granlund, Kenneth and Vermillion, Chris}, year={2020}, month={Nov} }