Control engineering deals with the control of complex dynamical systems. Most real control systems are non-linear. The output cannot be easily derived from several simultaneous inputs simply by knowing the output from each individual input, and the system behaviour can change dramatically depending on the various operating conditions. Engineers seek to maintain the stability and performance of these complex non-linear systems in the face of changing system parameters. Robust control theory addresses uncertainty in controller design, exploring the design space to find options insensitive to system changes. An EU-funded scientist developed powerful new control engineering algorithms within the context of the project 'Innovative control, identification and estimation methodologies for sustainable energy technologies' (ICIEMSET). They tackle the control of complex, uncertain systems using airborne wind turbines (wind energy conversion systems that exploit the aerodynamic forces generated by wings tethered to the ground like a kite) as the test case. The fellow developed numerous novel algorithms in the context of high-altitude wind power from controlled airfoils. The accurateness and robustness of the algorithms were tested experimentally in numerous real-world experiments employing airborne wind energy paradigms. A successful grant application enabled the fellow to further pursue experimental activities. As a result, the fellow achieved his goal of demonstrating the autonomous flight of a flexible tethered wing for at least four consecutive hours. ICIEMSET led to publication or acceptance of 21 articles in international peer-reviewed control journals with another one in review, a book chapter and numerous conference-related publications. The control system for tethered wings developed within ICIEMSET is one of the few successful demonstrations of such a system worldwide with extensive experimental data. Overall, ICIEMSET significantly advanced the field of robust control methodology development for non-linear dynamical systems. Project outcomes are broadly useful to scientists, designers and engineers in physics, engineering, biology and chemistry. The promise of wind energy harnessed at high altitudes is also closer to exploitation with the successful control of autonomous tethered wings or airborne wind turbines.
Dynamical systems, wind turbines, control engineering, non-linear, algorithm, autonomous, wind energy, airborne wind energy