Chiz-Chung Cheng

Nonlinear Control for Missile Terminal Guidance

Variable Structure Control (VSC) technique is applied to the design of robust homing missile guidance laws. In the design procedure, the target’s maneuver is assumed to be unpredictable and is considered as disturbances. Guidance laws are then proposed to achieve the interception performance for both cases of longitude-axis control being available and unavailable. The proposed guidance laws are continuous which alleviate chattering drawback by classic VSC design. Results are obtained and compared with those by realistic true proportional navigation design to illustrate the benefits of the proposed design. @S0022-0434~00!00604-3#

Reliable control of nonlinear systems via variable structure scheme

This study proposes a class of reliable Variable Structure Control (VSC) laws, which are shown to be able to tolerate the outage of actuators within a prespecified subset of actuators. The gain margins of guaranteeing system stability are estimated, which depend on control parameters and are larger than those obtained by LQR reliable design. In addition, this approach does-not need to solve the Hamilton-Jacobi equation or inequality, which is known difficult to solve and is an essential part in the reliable LQR and H/sub /spl infin// designs. As a matter of fact, this approach can also relax the computational load for solving the Hamilton-Jacobi inequality.

Robust Guidance Law via Integral-Sliding-Mode Scheme

B ECAUSE of the growing demand to minimize the threat of missile attacks, the study of guidance laws for antimissile systems has attracted considerable attention [1–7]. Among those existing studies, the proportional-navigation (PN) law and its generalization (e.g., ideal PN [1] and realistic true PN [2]) have been widely used for intercepting nonmaneuvering or low-maneuvering target due to the advantages of simplicity and easy implementation. Specifically, the PN law has been shown to be an optimal design in minimizing miss distance (MD) for the nonmaneuvering target [3]. However, the performance of PN and its generalization will become worse, and lack of robustness as the target’s maneuverability increases [4]. To overcome such a disadvantage, various control techniques have been recently employed to construct suitable guidance laws for the missile interception, such as the slidingmode-control (SMC)-based design [5–7], the optimal-controlbased scheme [3], and the state-dependent Riccati-equation-based guidance laws [8]. The SMC approach is known to have the advantages of rapid response, easy implementation, and strong robustness [5–7,9,10]. However, the conventional SMC scheme inevitably has to undergo a period of reaching phase, which might result in an undesirable high gain effect and be sensitive to model uncertainties and/or external disturbances (MUED) [10,11]. Instead, the integral SMC (ISMC) design was recently shown to be more effective in improving system performance [10,11]. One is that the maximum control magnitude required for the ISMC is usually smaller than that for the SMC because the maximum control magnitude of a typical SMC design usually occurs at the beginning of the reaching phase, but there is no reaching phase for the ISMC scheme. In addition, the effect of mismatched uncertainty will not be amplified in the sense of Euclidean norm by properly setting of the sliding-manifold parameters in the ISMC design. Moreover, the state responses of the nominal system and the matched-type uncertain system are identical via the ISMCapproach if the system states remain lying on the sliding manifold. In fact, the last two properties will be very helpful to provide the engineer with extra degree of freedom in the design of a suitable controller for the nominal system, and hence, creating a desired state trajectory for the uncertain system to follow. Thus, the performance of the uncertain system will be predictable. Such an advantage is generally not provided by using other nonlinear control techniques. Although an existing result [6] has proposed to employ the SMC scheme for missile-guidance control, however, that design inescapably experiences a reaching-phase period, which will suffer the aforementioned drawbacks, and the state performance of the uncertain system is not predictable from that of the nominal system. Motivated by the aforementioned benefits, this study will investigate the guidance-law design via the ISMC scheme.

Variable structure control scheme for landing on a celestial object

This paper considers the landing of a space vehicle on a celestial object. By assuming the air drag in two specific forms and the uncertainty in matching type, their effects are studied. Through the construction of a time-varying boundary layer, a new guidance control law for landing on a celestial object is proposed via the variable structure control (VSC) technique to guarantee that tracking performance is achieved at an exponential convergence rate. The proposed guidance law is continuous and alleviates chattering drawback by classic VSC design. Finally, simulation results are presented to illustrate the use of the main design.

Robust attitude control for spacecraft

The paper deals with the spacecraft attitude tracking problems in the presence of model uncertainties and external disturbances. A modified VSC design scheme is proposed by the use of variable structure control (VSC) design technique. These modified VSC laws are continuous, which are shown able to alleviate the chattering drawback inherited from sign-type VSC controllers and enhance the uniformly ultimate boundedness performance suffered by saturation-type ones to asymptotic stability level. Numerical simulations are also given to demonstrate the benefits of the proposed VSC scheme.

Application of VSC reliable design to spacecraft attitude tracking

This study investigates variable structure reliable control issues of nonlinear systems and its applications to spacecraft attitude tracking problems. The proposed passive reliable control laws must know in advance which group of actuators is allowed to fail. These reliable controllers need not the solution of Hamilton-Jacobi (HJ) equation or inequality that are essentials in optimal approaches such as LQR and H/sub /spl infin// reliable designs. As a matter of fact, this approach is able to relax the computational load in computing the solution of HJ equation. The proposed reliable designs are also applied to spacecraft attitude tracking problems to explain their effectiveness and benefits. Finally, simulation results and comparisons between LQR and variable structure control (VSC) reliable designs are presented to illustrate the merits of the proposed scheme. Although the proposed design is a passive one, it may provide a guideline for active design when a fault detection and diagnosis (FDD) scheme is available.

Study and implementation of a networking information platform for RFID system

RFID system has been treated as one of the important technologies which are enough to influence the evolutions of the global industry in the near future, especially for the supply chain and logistics management. The RFID technology may provide the requirements of the real-time tracking and high precision in the application of logistic systems. In this paper, a networking information platform integrated with RFID system is studied and proposed by using the internet techniques to increase the management capability and to achieve the network routing function of tag data for the enterprise applications. Since one of the most important factors for RFID applications is to construct the integrated and reliable system platform of networking information, this system platform will play one of key technologies for data routing and networking integration in the infrastructure of RFID systems. The main results of this paper are focused on developing the networking integration technologies to monitor the readers and capture the tag EPC data via Web server and the internet, and implementing the interfacing technologies of Savant middleware between RFID reader and database server to mediate the data flow from the clients to the enterprises. In conclusion, the networking information platform for RFID system is developed and evaluated to demonstrate the practical feasibility of RFID applications in this paper.

Nonlinear reliable output tracking control with application to bank-to-turn missile systems

This study investigates reliable output tracking control issues. Both passive and active reliable control laws are proposed using variable structure control (VSC) technique. These reliable controllers need not the solution of Hamilton-Jacobi equation or inequality, which are essentials in optimal approaches such as reliable LQR and H-infinity designs. As a matter of fact, this approach is able to relax the computational load. The proposed reliable designs are also applied to bank-to-turn missile systems to illustrate their benefits.

An energy efficiency scheme for the wireless communication used in intelligence transportation system

In this paper, we propose an energy efficiency scheme for the communication used in Intelligence Transportation System (ITS). The Rayleigh fading scenarios is first investigated to derive the optimal transmission range in ad-hoc wireless network by taking the factors of data loss and retransmission. In order to construct the energy efficiency protocol, the realistic physical layer model in ad-hoc wireless communication is also considred to fix the energy consumption model for constructing an energy efficiency based communication protocol. Both of numerical simulation and experimental results demonstrate the success of the proposed design.

VSC reliable design with application to spacecraft attitude tracking

This study investigates variable structure reliable control issues of nonlinear systems and its applications to spacecraft attitude tracking problems. Both passive and active reliable control laws are proposed using variable structure control (VSC) technique. The passive one must know which group of actuators is allowed to fail, while the active one must accompany a fault detection and diagnosis (FDD) scheme. Both the reliable controllers need not the solution of Hamilton-Jacobi equation or inequality, which are essentials in optimal approaches such as reliable LQR and Hinfin designs. As a matte of fact, the VSC approach is able to relax the computational latency in control law computing. The proposed reliable designs are also applied to spacecraft attitude tracking problems to explain their effectiveness and benefits. Finally, simulation results and comparisons between LQR and VSC reliable designs are given to illustrate the merits of the proposed scheme