A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item System identification for high-performance UAV control in wind(Wiley, 2023-08-14) Shastry, Animesh K.; Paley, Derek A.This article describes and experimentally evaluates a comprehensive system identification framework for high-performance UAV control in wind. The framework incorporates both linear offline and nonlinear online methods to estimate model parameters in support of a nonlinear model-based control implementation. Inertial parameters of the UAV are estimated using a frequency-domain linear system identification program by incorporating control data obtained from motor-speed sensing along with state estimates from an automated frequency sweep maneuver. The drag-force coefficients and external wind are estimated recursively in flight with a square-root unscented Kalman filter. A custom flight controller is developed to handle the computational demand of the online estimation and control. Flight experiments illustrate the nonlinear controller's tracking performance and enhanced gust rejection capability.Item A lionfish-inspired predation strategy in planar structured environments(Institute of Physics, 2023-06-30) Thompson, Anthony A.; Peterson, Ashley N.; McHenry, Matthew J.; Paley, Derek A.This paper investigates a pursuit-evasion game with a single pursuer and evader in a bounded environment, inspired by observations of predation attempts by lionfish (Pterois sp.). The pursuer tracks the evader with a pure pursuit strategy while using an additional bioinspired tactic to trap the evader, i.e. minimize the evader’s escape routes. Specifically, the pursuer employs symmetric appendages inspired by the large pectoral fins of lionfish, but this expansion increases its drag and therefore its work to capture the evader. The evader employs a bioinspired randomly-directed escape strategy to avoid capture and collisions with the boundary. Here we investigate the trade-off between minimizing the work to capture the evader and minimizing the evader’s escape routes. By using the pursuer’s expected work to capture as a cost function, we determine when the pursuer should expand its appendages as a function of the relative distance to the evader and the evader’s proximity to the boundary. Visualizing the pursuer’s expected work to capture everywhere in the bounded domain, yields additional insights about optimal pursuit trajectories and illustrates the role of the boundary in predator-prey interactions.