LQR Controller with Kalman Estimator Applied to UAV Longitudinal Dynamics

The aim of this study is designing an optimal controller with linear quadratic regulator (LQR) method for a small unmanned air vehicle (UAV). To better evaluate the effect of disturbances on the obtained measurements a Kalman filter is also used in the system. For this purpose a small UAV that is normally used as a radio controlled plane is chosen. The linearized equations for a wings level flight condition and the state space matrices are obtained. An optimal controller using LQR method to control the altitude level is then designed. The effect of the disturbances on the measurements are taken into account and the effectiveness of the Kalman filter in obtaining the correct measurements and achieving the desired control level are shown using the controller designed for the system. The small UAV is commanded to the desired altitude using the LQR controller through the control inputs elevator deflection and thrust rate. The LQR effectiveness matrices are chosen to find the gains necessary to build an effective altitude controller. Firstly the controller is tested under the situation where disturbances are absent. Then a Kalman filter is designed and the system under disturbances is tested with the designed controller and the filter. The results reveal the effectiveness of the Kalman filter and the LQR controller.

Vibration Control of FGM Piezoelectric Plate Based on LQR Genetic Search

Active vibration control of functionally graded material (FGM) plate with integrated piezoelectric layers is studied. In this regard, a finite element model based on the classical plate theory is adopted and extended to the case of FGM plate to obtain a space state equation. Rectangular four node and eight node elements are used for the analysis purpose. The material proprieties of FG plate are assumed to be graded along the thickness direction. In order to control the vibration of the plate, an LQR controller has been designed and developed. The weighing factors are obtained by using genetic algorithm. The proposed results of finite element modeling are verified with the results obtained using ANSYS. Also the validation of methodology is done with comparing the results with that of available in literature and found in well agreement. Further analysis is performed for three sets of power law exponent n = 0, 1 and 100 which gives benchmark results for vibration control of FGM piezoelectric plate.

Robust Control Design of Wheeled Inverted Pendulum Assistant Robot

This paper examines the design concept and mobile control strategy of the human assistant robot I-PENTAR(inverted pendulum type assistant robot). The motion equation is derived considering the non-holonomic constraint of the twowheeled mobile robot. Different optimal control approaches are applied to a linearized model of I-PENTAR. These include linear quadratic regulator(LQR), linear quadratic Gaussian control(LQG), H_2 control and H_∞ control. Simulation is performed for all the approaches yielding good performance results.

A hybrid LQR-PID control design for seismic control of buildings equipped with ATMD

This paper presents an efficient hybrid control approach through combining the idea of proportional- integral-derivative （PID） controller and linear quadratic regulator （LQR） control algorithm. The proposed LQR-PID controller, while having the advantage of the classical PID controller, is easy to implement in seismic-excited structures. Using an optimization procedure based on a cuckoo search （CS） algorithm, the LQR-PID controller is designed for a seismic- excited structure equipped with an active tuned mass damper （ATMD）. Considering four earthquakes, the performance of the proposed LQR-PID controller is evaluated. Then, the results are compared with those given by a LQR controller. The simulation results indicate that the LQR-PID performs better than the LQR controller in reduction of seismic responses of the structure in the terms of displacement and acceleration of stories of the structure.

Dynamic wheeled motion control of wheel-biped transformable robots

Most existing biped robots can only walk with their feet or move by wheels.To combine the best of both worlds,this paper introduces the dynamic wheeled control including wheeled locomotion and in-situ wheel-to-foot(WtF)transformation of a full-sized wheel-biped transformable robot SR600-II.It can traverse on flat surfaces by wheels and transform to footed stance through its switching modules when facing obstacles.For wheeled locomotion,the kinematics considering upper-body lumped center-of-mass(CoM)constraint is first derived.Then,the dynamics of wheeled locomotion is modeled as a wheeled inverted pendulum(WIP)with variables related to the pose of upper body.After that,a parameter-varying linear quadratic regulator(LQR)controller is utilized to enable dynamic wheeled locomotion.For WtF transformation,the WtF balance constraints are first revealed.Then,a WtF transformation strategy is proposed to tackle the problem when robot transforms from wheeled balance state to in-situ biped stance state.It enables the robot to pass by the transition stages in which both wheels and feet touch the ground and to maintain its balance at the same time.Simulations and experiments on the SR600-II prototype have validated the efficacy of proposed dynamic wheeled control strategies for both wheeled locomotion and in-situ WtF transformation.

A linear quadratic regulator control of a stand-alone PEM fuelcell power plant

This paper introduces a technique based on linear quadratic regulator （LQR） to control the output voltage at the load point versus load variation from a stand- alone proton exchange membrane （PEM） fuel cell power plant （FCPP） for a group housing use. The controller modifies the optimal gains ki by minimizing a cost function, and the phase angle of the AC output voltage to control the active and reactive power output from an FCPP to match the terminal load. The control actions are based on feedback signals from the terminal load, output voltage and fuel cell feedback current. The topology chosen for the simulation consists of a 45 kW proton exchange membrane fuel cell （PEMFC）, boost type DC/ DC converter, a three-phase DC/AC inverter followed by an LC filter. Simulation results show that the proposed control strategy operated at low commutation frequency （2 kHz） offers good performances versus load variations with low total harmonic distortions （THD）, which is very useful for high power applications.