Seong-Ho Song

H ∞ control of discrete-time linear systems with norm-bounded uncertainties and time delay in state

This paper deals with H∞ control problem for discrete-time linear systems with norm-bounded uncertainties and time delay in state. In terms of a modified Riccati inequality for discrete-time linear systems, a sufficient condition is presented and a state feedback control law is also given. The proposed control law is a memoryless state feedback control law.

A LOS rate estimation method for bank-to-turn missiles

We compensate for the effect of the fast roll motion of bank-to-turn (BTT) missiles through appropriate coordinate transformation. Thereby, the proposed line-of-sight (LOS) rate estimator can provide better estimation performance than the previously known passive target tracking methods since it is independent of seeker-stabilization loop and robust with the measurement noise.

Robust adaptive control of uncertain nonlinear systems via disturbance observer techniques

This paper deals with robust control problems for nonlinear systems with matched uncertainties. In order to handle the uncertainties, the uncertainties are considered as disturbances. First, a disturbance observer is designed and the uncertainties can be rejected by subtracting these estimated values of disturbances from the plant input. Since the disturbance observer is a kind of low-pass filter, it has inevitably estimation errors. To get rid of the effects of these errors, the additional control should be applied. This additional control input is designed using adaptive control scheme. The unknown disturbance error bounds are estimated by adaptive parameter estimation methods and then the control input is calculated using these estimate values. But the control input needs to be switched on the sliding surface and provokes a chattering phenomenon. The control method suggested in this paper can, however, reduce the chattering phenomenon as small as possible by using large disturbance observer gain because the magnitude of the switching control input is dependent on the disturbance estimation errors which are decided by the accuracy of the designed disturbance observer.

A GHz I-Q quadrature signal generator using cellular oscillator network

The design of a GHz I-Q and Signal CMOS Generator using a Cellular Oscillator Network architecture is presented and analyzed. With its high speed for settling and easy frequency controllability, this I-Q signal generation method can be used in RF communication systems, where GHz range quadrature signals are needed. Also, a technique is presented for a sleeping mode with a small settling time. This model is simulated and proved with typical 3 V, 0.5 /spl mu/ CMOS N-well process parameters.

Singular perturbationlike approach to compensation of actuator dynamics effect in missile control

Our recently developed nonlinear autopilot controller can make the input-output (I/O) dynamic characteristics of the nonlinear bank-to-turn (BTT) missile system linear and independent of flight conditions. However, relatively slow actuator dynamics can degrade its performance significantly. The proposed compensation method can nearly eliminate the effect of slow actuator dynamics while maintaining the desired linear I/O dynamic characteristics. It considers fully the nonminimum-phase nonlinear BTT missile dynamics but requires no differentiations of noisy variables, unlike other existing control methods.

Hybrid Indoor Location Tracking for Pedestrian Using a Smartphone

In this paper, a hybrid indoor location tracking method is proposed for pedestrian using a set of inertial sensors embedded in smartphones. The method is composed of two localization techniques; one is dead-reckoning using inertial sensors and the other is Wi-Fi fingerprinting. The proposed method uses the concept of combined map of topological and geometric map. Introducing user-select points of interest in his/her workplace we can reduce the cost of building a radio map for Wi-Fi fingerprinting method. The dead-reckoning method can track incremental movements of user by detecting steps. Based on acceleration signals we proposed a method to estimate the orientation and position of the phone in a pocket of pants. Experiments verified the performance of the method.

A Singular Perturbation-like Method to Compensate the Effect of Fin-Actuator Dynamics in Nonlinear Missile Control

The recently developed autopilot controller can make the input-output (I/O) dynamic characteristics of the nonlinear missile dynamics linear and independent of flight conditions. However, significant fin-actuator dynamics can degenerate the I/O dynamics performance of the overall system. In this paper, we propose a singular perturbation-like method to compensate the effect of significant fin-actuator dynamics in nonlinear missile control. The proposed compensation method does not require the time derivatives of fin angles but can maintain the linear I/O dynamic characteristics provided by the recently developed autopilot controller

L/sub 2/ stability and performance analysis of missile systems with linear autopilots and PN guidance laws

This note presents the stability analysis for missile guidance systems with linear time-invariant autopilot systems. The concept of L/sub 2/ stability is employed in order to analyze missile systems. The well-known PN guidance law is considered as a missile guidance law and the nonlinear planar pursuit situation is fully considered in the analysis. It is shown first that the missile systems can be L/sub 2/ stable for target acceleration inputs which belong to L/sub 2/ space. A sufficient condition for a missile autopilot transfer function to guarantee L/sub 2/ stability of the missile systems is also provided as a function of total miss distance, which offers a criterion for missile autopilot design.

A Sufficient Condition for the Feedback Quasilinearization of Control Mechanical Systems

We derive a sufficient condition for feedback quasilinearizability of control mechanical systems and apply it to show the feedback quasilinearizability of the Acrobot system.

Theoretical Design and Analysis of EDFA Gain Control System Based on Two-Level EDFA Model

Control and management of erbium-doped fiber amplifiers (EDFAs) is an important design problem in the evolution towards a dynamic optical network [1]. As wavelengthdivision multiplexed networks increase in complexity, there remain a number of challenges, such as dealing with disturbances related to intrinsic network characteristics. The power level of each channel in WDM networks should be unchanged when channel add/drops or active rearrangements of network occur. Keeping the signal powers to a constant value is more important when the signals are amplified through EDFAs. At the EDFA, the change of the number of signals causes the change of the amplifier gain of each signal due to the cross gain saturation effect [2, 3, 4] which results in gain-related errors at the receivers.