Papers by Keyword: LQG

Abstract: This paper discussed an elastic-plastic time-history analysis on a structure with MR dampers based on member model, in which the elastoplastic member of the structure is assumed to be single component model and simulated by threefold line stiffness retrograde model. In order to obtain better control effect, Linear Quadratic Gaussian (LQG) control algorithm is used to calculate the optimal control force, and Hrovat boundary optimal control strategy is used to describe the adjustable damping force range of MR damper. The effectiveness of the MR damper based on LQG algorithm to control the response of the structure was investigated. The results from numerical simulations demonstrate that LQG algorithm can effectively improve the response of the structure against seismic excitations only with acceleration feedback.

Abstract: In this paper, the derivation of dynamic model of a robot arm on a two wheeled moving platform, and design of controllers to stabilize the robot arm are presented. The modeling of two wheeled moving platform is conducted through Simmechanics^® toolbox of Matlab^® software. Considered control approaches are PID control and linear quadratic gaussian (LGQ) for the dynamic system. The controllers are designed by using linearized model devised from Simmechanics^®. Simulation studies are discussed. Control approaches are compared in detail in terms of tracking precision, quality of control signal. The aims of this study are derivation of linearized model for designing controllers, and determining the most appropriate controller for the real time system.

Abstract: In order to meet the ride comfort of the heavy truck cab, the 1/2 heavy truck cab active suspension model established. Based on this model the LQG optimization control was selected for the active control of a 1/2 heavy truck cab suspension system. The road disturbance is integral white noise stochastic signal. By the example simulation in Matlab/Simulink, the results show that the cab active suspension with LQG control strategy can decrease the vertical accelerations, the roll angle and roll angle acceleration of the truck cab, the active suspension can improve both the ride comfort and driving safety.

Abstract: Modern tall buildings are more flexible so occur excessive wind-induced vibration resulting in occupant discomfort and structural safety. Many studies to reduce such a wind-induced vibration using a feedback controller and auxiliary devices have been conducted .The optimal control law of linear quadratic Gaussian (LQG) controller is used for reducing the across-wind vibration response of a tall building with an active mass damper (AMD). Fluctuating across-wind load treated as a Gaussian white noise process is simulated numerically in time domain. And using this simulated across-wind load estimated across-wind vibration responses of tall building with AMD using LQG controller.

Abstract: The active vibration control of the flexible cantilever beam with PZT actuators was studied in this paper, and the principle and the method of the active vibration control were analyzed. First, using the balanced reduction method to reduce the model was carried out; the reduced model would be controlled. The placement of the piezoelectric actuators was utmost important, the optimization arrangement of the piezoelectric actuators was studied in this paper basing on the modal influential matrix of the piezoelectric actuators in order to make it to maximize its effectiveness to realize active control. Next step the LQG/LTR method is used to control the structure, then the LQR method was adopted to control the beam, and the two methods were compared. The results show that the LQG/LTR method to control the beam will realize effective control if only the treatment is adequate, when the acoustic noise and Interference were added to the system.

Abstract: The main goal of using mechatronic suspensions is to improve the ride comfort and handling performance. In this work, a robust linear controller for such a system was designed based on the μ synthesis method. The performance of a model two degree of freedom quarter car with parameter perturbations, subjected to road disturbances, was simulated and the time domain responses were analyzed. The simulation results indicate that the robust controller improved the vibration isolation performance of the mechatronic suspension system, despite the presence of parameter perturbations and exogenous disturbances. When compared to both LQG active control and to a passive suspension system, the μ synthesis controller also showed super or performance.

Abstract: In this paper, the CVT shifting control system based on vehicle operating conditions is modeled and simulated using MATLAB/SIMULINK. The modeling stage begins with the derivation of required mathematical model to illustrate the CVT shifting control system. Then, Linear Quadratic Gaussian (LQG), Proportional- Integrated-Derivative (PID) and Pole Placement are applied for controlling the shifting speed ratio of the modeled CVT shifting system. Simulation results of shifting controllers are presented in time domain and the results obtained with LQG are compared with the results of PID and Pole placement technique. Finally, the performances of shifting speed ratio controller systems are analyzed in order to choose which control method offers the better performance with respect to the desired speed ratio. According to simulation results, the LQG controller delivers better performance than PID and Pole Placement controller.

Abstract: Modern tall buildings using high strength and lighter construction materials are more flexible so could be excessive wind-induced vibrations resulting in occupant discomfort and structural unsafety . Recently, many studies have been advanced in using actuator force as an active control force based on the linear quadratic optimum control theory. It needs to predict the wind-induced response and the optimum control force to reduce the excessive wind-induced vibration. It takes a lot of time and cost to do wind tunnel test needed it, so numerical simulation approach instead of that is recommended sometimes. Simulating wind load in the time domain using known spectra data of fluctuating wind load is particularly useful for some prediction of windinduced vibration which is more or less narrow banded process such as across-wind response of a tall building. The simulation procedure is taken from Deodatis. In this study, fluctuating across-wind load acting on a tall building was simulated numerically in the time domain using the across-wind load spectra proposed by A.Kareem in1982. And using this simulated across-wind load estimated the reduced across-wind vibration response of a tall building using the linear quadratic Gaussian (LQG) control method.

Abstract: A PWM controller is designed for the active suspension without external energy supply (ASWEES) using the LQG control method. Based on the quarter-vehicle ASWEES model, Energy flow equation between the suspension and the accumulator with a 2 kW load was deduced and a PWM controller was designed. When 200Hz solenoid valves were adopted, the carrier frequency and series value of the carrier signal were set as 40 and 5 respectively. Simulation results show the suspension quadratic performance index of ASWEES decreases 24.97% than that of the passive suspension. The passive suspension consumes 2.211kW power, but ASWEES reclaims energy of 2 kW.

Abstract: Load follow is necessary in the operation of a power plant due to the need of power changing with time. In the load following of a nuclear plant, many special factors have to be considered, which makes the control strategy particularly difficult as well as important. Among many strategies, Linear Quadratic Gaussian and Loop Transfer Recovery (LQG/LTR) design approach is an efficient method for L-F, and is applied to a model of a practical nuclear reactor. The simulation shows the robust control method LQG/LTR meet the control requirements of the neutron flux spatial distribution during load following. And a Kalman-filter based feedback control is also applied in this approach to eliminate the oscillations caused by Xenon poisoning within the nuclear reactor.