In this study, active vibration control of a cantilevered flexible beam structure equipped with bonded piezoelectric sensor/actuators is investigated. The linear quadratic regulator technique together with an observer is adopted to design the controller as well as to provide the full-state feedback. Two different approaches are subsequently used for simultaneously integrated optimization of the controller and observer parameters. In the first approach, a linear experimental model of the system is obtained using identification techniques, and the optimization is then performed based on a computer simulation of the system. However, in the second approach, a hardware-in-the-loop optimization scheme is proposed and applied to automatically tune the parameters. In both cases, a hybrid metaheuristic algorithm called tabu continuous ant colony system is utilized to find the optimal controller and observer. The integrated performance is experimentally evaluated to demonstrate effectiveness of the proposed hardware-in-the-loop optimization method. Finally, a comparison is made between the frequency response of the current controller with a pole placement controller from the literature in order to assess the improvement achieved through hardware-in-the-loop optimization.
In this study, the guidance and control problem of a single-channel spinning missile is investigated. The missile utilizes a single ON-OFF actuator to drive a pair of control surfaces (e.g. elevators) and consequently to perform all required lateral maneouvers. An approximated linear response of the so-called non-rotating frame to ON-OFF input, applied to the rotating frame, is derived using the multiple-input describing function technique. It is shown that there is a relationship between the response of the non-rotating frame and that of the equivalent non-rotating body. It is also shown that the two-channel flight controller, designed for the equivalent non-rotating body, can be reduced to a single-channel controller, the output of which is applied to the rotating body. A necessary condition is introduced for this purpose. A proportional navigation guidance law for such a spinning missile is also introduced that generates an angular rate command instead of the acceleration command. Finally, the performance of the proposed controller in the presence of noise and uncertainties is validated through flight simulations.
This paper proposes an extension of the Gravitational Search Algorithm (GSA) to multi-objective optimization problems. The new algorithm, called Non-dominated Sorting GSA (NSGSA), utilizes the non-dominated sorting concept to update the gravitational acceleration of the particles. An external archive is also used to store the Pareto optimal solutions and to provide some elitism. It also guides the search toward the non-crowding and the extreme regions of the Pareto front. A new criterion is proposed to update the external archive and two new mutation operators are also proposed to promote the diversity within the swarm. Numerical results show that NSGSA can obtain comparable and even better performances as compared to the previous multi-objective variant of GSA and some other multi-objective optimization algorithms.
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