A comprehensive design procedure based on extremum seeking for minimum power demand formation ight is presented, the rst with performance guarantees. The procedure involves the design of a new wake robust formation hold autopilot and transformation of the closed-loop aircraft dynamics to a form in which a newly available rigorous design procedure for extremum seeking is applicable. The design procedure is applied to a formation of Lockheed C-5s, extending the use of maximum performance formation ight to large transports. By the use of available experimental wake data of the C-5, a model of the aircraft in the wake is developed that models aerodynamic interference as feedback nonlinearities. Thus, this work is also the rst to attain stable extremum seeking for a plant with nonlinear feedback. Optimal formation ight is attained by online minimization of an easily measurable objective, the pitch angle of the wingman.
This article considers the question of dynamic image-based visual servo control for a vertical take-off and landing unmanned aerial vehicle. The visual targets considered are colored blobs on a flat surface to which the normal direction is known. A fully nonlinear adaptive control design coupled with an asymptotic filter is provided that ensures the stability of the closed-loop system in a large domain. The image features used are a modified first order spherical moment for position regulation and optic flow for velocity damping.
We present a comprehensive design procedure based on extremum seeking for minimum power demand formation flight, the first with performance guarantees. The procedure involves the design of a new wake robust formation hold autopilot, and transformation of the closed loop aircraft dynamics to a form in which a newly available rigorous design procedure for extremum seeking is applicable. We apply the design procedure on a formation of Lockheed C-5s, extending the use of maximum performance formation flight to large transports. Using available experimental wake data of the C-5, we develop a model of the aircraft in the wake that models aerodynamic interference as feedback nonlinearities. Thus, our work is also the first to attain stable extremum seeking for a plant with nonlinear feedback. Optimal formation flight is attained by online minimization of an easily measurable objective, the pitch angle of the wingman. Motivation and P r i o r WorkBy flying in formation, two aircraft can achieve a significant reduction in power demand (up to 20%) through aerodynamic interference, by the wingman riding upon the upwash field of the leader, like a glider in a thermal. Given the potential payoffs, and the availability of enabling avionics and control algorithms, the problem of attaining the configuration for minimum power demand through automatic control of the wingman has lately been a subject of intense interest [3, 5, 81. Given the high sensitivity of formation benefits to positioning error (an error of just 10% of the aircraft wingspan can reduce the benefits by half [2]), and the uncertainty in aerodynamic interference modeling, i.e., the need for accurate steady state performance in the presence of modeling uncertainty, there is a definite need for adaptive feedback control. The wingman control system is based on a formation-hold autopilot', which is fed an estimate of the optimal separation generated by an adaptive feedback control scheme. The nature of the problem has led to the use of extremum seeking algorithms [3, 81. In [SI, a simple discrete time extremum seeking algorithm to maximize aileron deflection was used to attain a power demand reduction of 20% in experimental flight tests of two Dornier aircraft in formation. In [3], simulation studies of a continuous time extremum seeking algorithm to maximize induced lift were presented. A systematic design procedure was absent in both.' This work was supported in part by grants from AFOSR, Corresponding author. Email: kariyur@mae.ucsd.edu. ONR, and NSF' An autopilot capable of tracking relative position (with respect to the leader) reference signals. [3,8], and supplies a generally applicable, com;prehensiue design procedure for minimum power demand fo:mation flight with performance guarantees, and an easily measurable objective for eztremum seeking. This goal is attained through the following steps: This work solves the problems left open by1. 2. 3. 4. 5.Modeling of aerodynamic interference as a multiple feedback nonlinearity in the aircraft dynamics.Linking po...
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