Papers by Keyword: LQR

Abstract: A cable-net reflector is fist introduced and then the state space representation is derived based on the finite element model. Modal analysis is carried out for the purpose of vibration control in modal space. The first several natural frequencies and vibration modes are obtained to analyze the vibration characteristics. The optimal control theory based on LQR with full state feedback is used for the control problem. Numerical simulations of the impulse disturbance response and the frequency response are implemented. Also, the contrast between the uncontrolled and controlled cases is illustrated. The theoretical results confirm the effectiveness of the proposed active control strategy for the vibration suppress of the cable-net reflector.

Abstract: This paper presents a method for the estimation of unknown disturbances for high precision gimbal systems. Alternative to the classical methods of model inversion and filtering, we employ an asymptotically stabilizing controller which achieves the estimation process even in the presence of unstable zeros. The architecture provides an input equivalent disturbance which can be thought to capture all real disturbances in the system as well as virtual ones such as unmodelled dynamics and nonlinearities. The proposed method is illustrated on a 2-axis gimbal system where system identification is followed by the design on an integral linear quadratic regulator as the stabilizing controller which forms the base of the disturbance observer. It is seen that a random unknown disturbance is estimated successfully in the presence of additional gyro noise.

Abstract: The LQR controller is designed to control magnetorheological damper through controlling the output damping force of magnetorheological damper. Simulation models of LQR controller is built. The results of LQR models and simulation model of landing gear is compared that LQR have a good control effect.

Abstract: A new approach substitutes the damper of a passenger car by a cardanic gimbaled flywheel mass. The constructive design leads to a rotary damper in which the vertical movement of the wheel carrier leads to revolution of the rotational axis of the flywheel. In this arrangement, the occurring precession moments are used to control damping moments and to store vibration energy. Different damper characteristics are achieved by different velocities of the inner ring. From almost zero torque output to high torque output, this damper has a huge spread. In this paper a control concept for a LQR is presented. The objective of the control is an adequate motion of the gyroscope to a desired damping characteristic of a passenger car.

Abstract: The focus of this paper is uncertainty modeling and controller designing of air-breathing hypersonic vehicle. First, the hypersonic vehicle longitudinal dynamics model is made on the base of the fitting of aerodynamic parameters. As to the uncertainty of model parameters, a linear model of the uncertain part is established and the LQR controller parameters are thereupon designed with state transition and a first-order Taylor series expansion method, based on feedback linearization of the system. The simulation results that the hypersonic flight control system stated in this paper can well realize the tracking of speed and trajectory angle input command under the situation of floating model parameters.

Abstract: For the instability of the inverted pendulum, a LQR controller is designed based on optimal control algorithm in this paper, which can control the pendulum angle and the cart position at the same time. The basic principle of LQR optimal control is analyzed and the LQR controller is designed and simulated in this paper. The simulation results show that the designed controller is effective. It has a good effect of equilibrium and stability control, and the system's anti-interference ability is improved.

Abstract: Modern control theory has been used to design a variable pitch controller based on disturbance accommodating. The controller realizes the optimal control which minimized the controller action and drive-train torque. A torque controller based on pole clustering had been designed to enhance drive system damping and to suppress torque ripple. The federated control of variable pitch and torque is adopted to reduce drive system dynamic torsional load, and has been verified by software MATLAB and FAST. Simulation result illustrated that drive system dynamic torsional load can be controlled to improve reliability of wind turbine and extend life of critical components by active control method.

Abstract: There has been wide interest in the control scheme of the electromagnetic levitation system due to its disadvantages of nonlinearity and open-loop uncertainty. A typical coil-ball levitation system is used in research. The forces of the ball are analyzed and a dynamic model of the whole electromagnetic levitation system is established. Based on the nonlinear state-space model, the coil-ball system is linearized and then a LQR control approach is proposed. Simulation results show that, compared with conventional pole assignment scheme, the electromagnetic levitation system under the proposed control approach gets a better performance, including smaller overshot and faster response.

Abstract: This paper considered the optimal placement of collocated piezoelectric actuator-sensor pairs on a thin cantilever plate using a modal-based linear quadratic independent modal space controller. LQR performance was taken as objective for finding the optimal location of sensor–actuator pairs.The discrete optimal sensor and actuator location problem was formulated in the framework of a zero–one optimization problem,which was solved by real-coded adaptive genetic algorithm (AGA). The vibration response of the piezoelectric plate was calculated using the finite element method (FEM).The optimization and vibration control programs were written by FORTRAN language. The results of numrical examples show that the adaptive genetic algorithm based on the minimum of LQR performance for the optimal location of sensors and actuators is feasible and effective.

Abstract: -In this paper , performance of fuzzy PD , fuzzy PI , fuzzy PD+I , fuzzy PID controllers are evaluated and compared. This paper also describes the speed control based on Linear Quadratic Regulator (LQR) technique. The comparison is based on their ability of controlling the speed of DC motor, which merely focuses on performance index of the controllers, and also time domain specifications such as rise time, settling time and peak overshoot. The controller is modelled using MATLAB software, the simulation results shows that the fuzzy PID controllers are the best performing candidates in all aspects but it as higher overshoot and IAE in comparison with optimal LQR. The Fuzzy PI controller exhibited null offset but suffers from poor stability and peak overshoot, whereas the fuzzy PD controller has fast rise time, with no overshoots but the IAE is much greater. Thus, the comparative analysis recommends fuzzy PID controller but it is usually associated with complicated rule base and tedious tuning. To circumvent these problems, the proposed LQR controller gives better performance than the other controllers.