Mathematical control of complex systems

Copyright © 2013 ZidongWang et al.This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Hysteresis-based design of dynamic reference trajectories to avoid saturation in controlled wind turbines

The main objective of this paper is to design a dynamic reference trajectory based on hysteresis to avoid saturation in controlled wind turbines. Basically, the torque controller and pitch controller set-points are hysteretically manipulated to avoid saturation and drive the system with smooth dynamic changes. Simulation results obtained from a 5MW wind turbine benchmark model show that our proposed strategy has a clear added value with respect to the baseline controller (a well-known and accepted industrial wind turbine controller). Moreover, the proposed strategy has been tested in healthy conditions but also in the presence of a realistic fault where the baseline controller caused saturation to nally conduct to instability.Peer ReviewedPostprint (author's final draft

Damage Tolerant Active Contro l: Concept and State of the Art

Damage tolerant active control is a new research area relating to fault tolerant control design applied to mechanical structures. It encompasses several techniques already used to design controllers and to detect and to diagnose faults, as well to monitor structural integrity. Brief reviews of the common intersections of these areas are presented, with the purpose to clarify its relations and also to justify the new controller design paradigm. Some examples help to better understand the role of the new area

FLUTTER SUPPRESSION BY ACTIVE CONTROLLER OF A TWO-DIMENSIONAL WING WITH A FLAP

Flutter is a divergent oscillation of an aeroelastic structure, and one of a family of aeroelastic instability phenomena, that results from the interaction of elastic and inertial forces of the structure with the surrounding aerodynamic forces. Airfoil Flutter is important due to its catastrophic effect on the durability and operational safety of the structure. Traditionally, flutter is prevented within an aircraft\u27s flight envelope using passive approaches such as optimizing stiffness distribution, mass balancing, or modifying geometry during the design phase. Although these methods are effective but they led to heavier airfoil designs. On the other hand, active control methods allow for less weight and higher manoeuvring capabilities. The main objective of this study is to investigate the potential effectiveness of using Model Predictive Control MPC as an active control strategy to suppress flutter. Lagrange’s energy method and Theodore’s unsteady aerodynamic theory were employed to derive the equations of motion of a typical 2D wing section with a flap. Using MATLAB®, the airspeed at which the flutter occurs for a specific wing’s parameters were found to be 23.96 m/s, at a frequency of 6.12 Hz. A Linear Quadratic Gaussian compensator LQG was designed and simulated. MATLAB® was also used to design and simulate a discrete MPC using Laguerre orthonormal functions. The simulated results for states regulation and reference tracking tasks in the flutter airspeed region from both controllers were compared and discussed in terms of quantitative performance measures and performance indices. The results showed that both LQG and MPC are powerful in suppressing the flutter in addition to their effectiveness in tracking a reference input rapidly and accurately with zero steady-state error. The superiority for the constrained MPC is manifested by results comparison. MPC were able to save more than 40% of the needed settling time for states regulation task. Furthermore, it performed the job with much less control energy indicated by the ISE and ISU indices. On top of that, the key advantage of MPC, which is the ability to perform real-time optimization with hard constraints on input variables, was confirmed

Advanced robust control strategies of mechatronic suspensions for cars

Two novel mechatronic suspensions for road vehicles are studied in this thesis: the Series Active Variable Geometry Suspension (SAVGS) and the Parallel Active Link Suspension (PALS). The SAVGS and the PALS complement each other in terms of the vehicle categories they serve, which range from light high-performance vehicles (the Grand Tourer) to heavy SUV vehicles, respectively, based on the sprung mass and the passive suspension stiffness. Previous work developed various control methodologies for these types of suspension. Compared to existing active suspension solutions, both the SAVGS and the PALS are capable of low-frequency chassis attitude control and high-frequency ride comfort and road holding enhancement. In order to solve the limitation of both SAVGS and PALS robustness, mu-synthesis control methodologies are first developed for SAVGS and PALS, respectively, to account for structured uncertainties arising from changes to system parameters within realistic operating ranges. Subsequently, to guarantee robustness of both low-frequency and high-frequency vehicle dynamics for PALS, the mu-synthesis scheme is combined with proportional-integral-derivative (PID) control, employing a frequency separation paradigm. Moreover, as an alternative robustness guaranteeing scheme that captures plant nonlinearities and road unevenness as uncertainties and disturbances, a novel robust model predictive control (RMPC) based methodology is proposed for the SAVGS, motivated by the promise shown by RMPC in other industrial applications. Finally, aiming to provide further performance stability and improvements, feedforward control is developed for the PALS. Nonlinear simulations with a set of ISO driving situations are performed to evaluate the efficiency and effectiveness of the proposed control methods in this thesis.Open Acces