In this paper the vibration suppression of a flexible structure using fuzzy controller with bonded piezoelements is investigated. A flexible beam with PZT piezoceramics as sensor and actuators is fabricated at the Advanced Dynamic and Control Systems lab (ADCSL). A dynamic model of the smart structure is derived from an experimental system ID. On the other hand using finite element method (FEM), a theoretical model of the structure is obtained which is in good agreement with the experimental model. A fuzzy control system is then designed and implemented for vibration suppression of the smart beam subjected to the impulse excitation and resonance disturbances. Results show the effectiveness of the fuzzy controller and its advantage over conventional controllers.
An experimental setup is designed and fabricated to measure the force induced by voltage in an SMA wire. Using
autoregressive model with exogenous input (ARX) method for system identification of the experimental data, two
appropriate transfer functions of the force in SMA wire versus the applied voltage during each of heating and cooling
processes were derived. Afterwards, a conventional PID controller and a self-tuning fuzzy PID controller were
designed to control the force in SMA wire. The latter control algorithm is used by tuning the parameters of the PID
controller thereby integrating fuzzy inference and producing a fuzzy adaptive PID controller, which is used to
improve the force control performance. The responses of the system with the both designed controllers for different
inputs are simulated and compared to each other. At the end, simulation results show that in force control of the
SMA wire, self-tuning fuzzy PID controllers are more efficient than conventional PID controllers.
This research is conducted to demonstrate the advantages of skyhook semi-active dampers in railway vehicle suspension systems. This semi- active suspension system consists of four actuators on each bogie that locate in the secondary suspension position instead of passive dampers. Employing equations of skyhook control scheme, the semi- active damping force (actuator force) is determined by absolute velocity of car body instead of relative velocity. An integration of a control design tool, i.e. MATLAB, together with a tool for railway vehicle simulation, i.e. ADAMS/Rail is utilized for modeling and control analysis simultaneously. Analysis has been performed on a traditional bogie model with passive secondary suspension and on a new bogie model with semi-active suspension. The effects of suspension system on displacement and acceleration in passenger seats have been investigated in various points of car body. Results show that the semi-active suspension improves the ride comfort by reducing accelerations, in comparison with passive model. Finally, according to the damper force obtained from Sky-hook controller, a Magnetorheological (MR) damper has been designed for the semi-active suspension system.
This paper presents a new method used to determine the optimum group configuration of any specified number of piezoelectric actuators for vibration control of a flexible aircraft fin. A finite element model of the fin was used to obtain the frequency response function (FRF). The fitness function for optimization using a genetic algorithm was derived directly from this FRF, eliminating the need for a closed-form analytical solution. In comparison to the existing approaches, the novelty of this method is in that it allows optimization on much more complex geometries where the derivation of an analytical fitness (cost) function is prohibitive or impossible. Optimum configurations of pre-determined numbers of actuators are presented for single mode and multi-modal acceleration and displacement control criteria. Group efficiency and control authority are also examined, allowing a suitable number of actuators to be selected for any application. Actuator efficiency was higher for single mode control; however, actuation authority was much higher in multi modal control, reflecting the fact that it is desirable to select actuators that are able to exert substantial control authority over several modes.
This paper presents a parameter based form of a wave absorbing controller (WAC) in the time domain. The controller is applied to a flexible structure with the piezoceramic transducers bonded onto it. A distributed piezosensor gives the moment rate of the wave absorbing region as an output current. This current is then fed back to a piezoceramic actuator, resulting in a wave absorbing controller. The controller is originally designed in the frequency domain by minimization of the ratio of total output to total input wave amplitudes. Although the controller performance appears satisfactory in the frequency domain, its time domain behavior is of interest for overall performance evaluation. However, the wave absorbing method usually produces controllers which are difficult to realize in practice. In order to study the behavior of the controller and closed loop system in the time domain, and also to address these realization issues, we introduce a method of approximation of the controller enabling it to be represented in a simple form. Frequency domain comparison of system performance under the original controller and this approximation demonstrates the accuracy of the latter. The system is then studied in the time domain, showing that this novel wave absorbing controller is effective and can be easily implemented in practice. The main contribution of this paper is the introduction of a new controller for flexible structures, based on the wave absorbing method (WAM), which depends on only system parameters, i.e., E, I, (rho) , and natural frequencies. Therefore, rather than the usual controller design based on dynamic model (such as LQR) for obtaining control gains, these gains can be easily calculated from a simple formula based only on the mechanical parameters of the flexible structure.