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For large lifting body plane symmetric aircrafts, lateral maneuvering near the target may cause severe aerodynamic coupling between the lateral channels, possibly resulting in instability of the rolling channel. Aiming at this kind of coupling problem, the lateral system is decomposed based on the singular perturbation theory, and the cascade model of the inner and the outer loops is established. The outer loop is used as an example to design the sliding mode (SM) control law, and the stability of the closed-loop system is analyzed. The sliding mode disturbance observer (SMDO) is also employed to estimate and compensate for the coupling term and improves the robustness of the rolling channel against the lateral coupling. Simulation results show that the designed controller has good dynamic characteristics and anti-disturbance ability, improving the robustness and performance of the control system.

There exists a steady-state error in the closed-loop system output with some conventional linear active rejection control approaches when the pitch channel control variable of the near space vehicle is the angle of attack. In this study, a cascaded linear active disturbance rejection control approach based on the cascaded control idea is proposed. Both the inner-loop controller and the outer-loop controller are designed by the linear active disturbance rejection control method. The inner-loop is built by angular rate feedback to improve dynamic performance of the closed-loop system, and the outer-loop is built by angle of attack feedback to remove the undesired steady-state error. The approach is employed to a hypersonic near space vehicle autopilot. The numerical simulations show that the proposed approach preserves the performances on time domain and frequency domain as good as those of the conventional active disturbance rejection control approaches, and it has the better performances on disturbance rejection and angle of attack command tracking accuracy than those of some previous active disturbance rejection control approaches.

The angular rate is the derivative of pitch angle other than the derivative of angle of attack, there determinately exists a steady-state error in the closed-loop system output with the linear active rejection control in the case that the control variable is the angle of attack. In this study, an unbiased linear active disturbance rejection control approach based on two-loop control is proposed. The internal-loop is built by angular rate feedback to improve the damping, and the external-loop is built by angle of attack feedback to realize the system output accurately reproducing the reference input. Furthermore, a linear active disturbance rej ection control is applied for the external-loop controller design. The approach is employed to a hypersonic near space vehicle autopilot. The numerical simulations show that the proposed approach preserves the performance on frequency domain as good as that of the conventional active disturbance rejection control approach, the steady-state error of the closed-loop system is well removed, and the angle of attack command is tracked with better accuracy than that of some previous active disturbance rejection control approaches.

Few investigation interests have been focused on anti-windup design under Active Disturbance Rejection Control scheme. In this study, an anti-windup compensation strategy under ADRC scheme is proposed. The strategy is also a special case of the unified framework for anti-windup compensation. By feeding the actual plant input into the extended state observer, the extended state is correctly estimated while actuator saturation emerges, then the adequate controller output is accordingly produced to alleviate the adverse influence of actuator saturation on closed-loop dynamics. The approach is applied to a hypersonic near space vehicle pitch-axis autopilot design with fin-deflection saturation, the capability and effectiveness of the proposed approach is demonstrated by the results.

The angular rate is the derivative of pitch angle other than the derivative of angle of attack, there determinately exists a steady-state error in the closed-loop system output in the case that the control variable is the angle of attack. In this study, A linear compensation term is introduced into the extended state observer, and an unbiased linear active disturbance rejection control approach is proposed. The approach is employed to a hypersonic near space vehicle autopilot. The numeral simulations show that the proposed approach preserves the performance on frequency domain as good as that of the conventional active disturbance rejection control approach, furthermore, the steady-error of the closed system is removed simultaneously, and the angle of attack command is tracked with better accuracy than that of some previous active disturbance rejection control approaches.

This paper presents a compact self-decoupling dual band MIMO antenna that meets wireless local area network communication standards. The self-decoupling is taken place by purposely using a folded loop-shape element in the MIMO antenna. Furthermore, the feeding point of the element antenna is deliberately selected so as to produce both the two desired frequency bands. The whole loop structure is constructed to produce the lower frequency band while a portion of the loop is resonant to the higher frequency band. The MIMO antenna contains two folded loop-shape elements situated back-to-back with a closed inter-element distance of one-tenth wavelength of the lower band. The novelty of this MIMO antenna is attributed to the achievement of good isolation without using any other supplementary decoupling mechanisms. In addition, the properties of small in size, simple in structure, nearly omni-directional in radiation pattern with moderate radiation gain make the proposed MIMO antenna fully compatible and fairly attractive to the wireless and internet network applications.

This paper presents an improved H∞ guidance law with the terminal impact angle constraint for homing missiles. By regarding target maneuvers as exogenous disturbances, the missile guidance problem is formulated as a nonlinear disturbance attenuation control problem. Furthermore, by introducing the Lyapunov stability criteria into guidance dynamics, not only the small miss distance and the specified impact angle are obtained, but also the H∞ attenuation level and the stability of the closed-loop system are guaranteed. The numerical simulation shows that the proposed method has the effectiveness and the robustness for homing missiles against both non-maneuvering targets and maneuvering targets.

A novel controller, which is called fuzzy sliding mode controller and employs the classical topology, is presented. This paper considers the pitch channel controller design process based on a static-unstable flexible vehicle and proves the system equilibrium state at the origin is stable by using Lyapunov stability analysis method. The fixed point simulation is carried out to check the response characteristics in time domain and the property of tracking command signal. The simulation results show the robustness of the controller.

Usually the missile attitude control process in a large flight envelope has strong time-varying and nonlinear characteristics, so the controller parameter is difficultly scheduled with conventional PID control approach. In this study a linear active disturbance rejection control approach based on reduced-order linear extended state observer is proposed. The approach is employed to the attitude controller for a supersonic missile in attack with high angle. It is not hard to determine the proposed controller parameter, and the numeral simulations show that the presented approach has a very good capability on tracking attitude command.

A compact multiband planar monopole antenna is presented in this paper. The operating frequency bands of the proposed antenna cover the multiple wireless access protocols of GSM (880-960MHz), DCS (1710-1880MHz), WiMAX (3.23.6GHz), WLAN and Bluetooth (2.4GHz), and WLAN (5.15.35GHz). The antenna is constructed by two distinct monopoles which are individually located at the opposite side of the substrate; a broadband meander-line monopole is structured to create the triple lower frequency bands, on the other hand, a tree-type monopole is built not only to produce the dual higher frequency bands, but also to act as a proximity-coupled feed for the meander-line resonator. The antenna together with several attractive characteristics, such as small in size, broad in operating frequency band and omni-directional in radiation pattern, makes itself particularly suitable to the integrated mobile wireless access applications. The measurement results demonstrate the success of the antenna design approach.

In order to obtain the full advantages of modern mobile MIMO wireless access communication, a compact and low mutual coupling antenna array is essential. Hence, this paper presents a compact dual band two element MIMO antenna operating in the 2.4GHz and 5.2GHz bands for mobile wireless LAN application. The dual-band antenna element is structured with a planar two-branch inverted-L tree-type monopole, where, the two collinear inverted-L radiators have been purposely organized such that a squeezed element radiation pattern is obtainable. The MIMO antenna is then incorporated with two tree-type monopoles and a simple narrow band isolator to achieve an excellent mutual coupling performance. Besides, the characteristics of small size and nearly omnidirectional coverage in array radiation pattern make the proposed MIMO antenna entirely compatible with the mobile wireless network applications. The measurement results of the fabricated antenna array demonstrate the success of the suggested design topology.

This paper presents a compact dual band two element MIMO array covering the 2.4GHz and 5.2GHz bands for the modern mobile wireless LAN applications. The dual band antenna element is structured as a two-branch tree-type inverted-L monopole, where, the two collinear inverted-L radiators have been purposely organized such that an oblique element radiation pattern is obtainable. The MIMO array is then incorporated with two tree-type monopoles and a simple narrow band isolator to achieve an excellent mutual coupling performance. Besides, the characteristics of small size and nearly omnidirectional array radiation pattern make the proposed MIMO array entirely compatible with the mobile wireless network applications. The measurement results of the prototype antenna array demonstrate the success of the suggested design topology.

This paper presents a compact planar monopole antenna that covers the operating frequency bands of GSM (880-960MHz), DCS (1710-1880MHz), WiMAX (3.2-3.6GHz), WLAN and Bluetooth (2.4GHz), and WLAN (5.1-5.35GHz). The proposed antenna is incorporated with two distinct monopoles, a tree-type and a shaped meander-line type monopole, situated on the opposite side of the substrate; the shaped meander-line type monopole is tuned to create the triple lower frequency bands, on the other hand, the tree-type monopole is built not only to produce the two higher frequency bands, but also to act as a proximity coupling feed for the meander-line resonator. The noticeable originalities exhibited in this proposed antenna include the handiwork of shaped multiband meander-line monopole and the use of broadband proximity coupling mechanism. Both of them enable us to simply the tuning process of the broadband matched network and to reduce the antenna size as well. The proposed antenna accompanied with several attractive characteristics makes itself particularly suitable to the modern integrated mobile wireless access applications.

This paper presents a kind of CPW-Fed Multi-Broadband Monopole Antenna, which provides an integrated operating bandwidth coverage from 900MHz of GSM, WLANs up to 10.6GHz of UWB. This is the antenna particularly desirable for modern integrated mobile broadband wireless radio access applications. The property of wide range in multiple broadband appeared in the proposed antenna has been created judiciously by using a folded-line loaded monopole with an edge-coupling mechanism. The measurement result shows the success of this novel design approach.

A cross-dipole antenna surrounded by four pins is used as a radiating element for a finite-element phased array. To achieve near-hemispherical radiation coverage and high gain under the consideration of mutual coupling effects, a method using genetic algorithms to optimize the design parameters of a cross-dipole antenna is presented. A method of moment code performs the task of evaluating each of the antenna designs generated by the genetic algorithm (GA) during the optimization process. To illustrate the capabilities of this approach, the numerical results are compared to the measured ones, showing excellent agreement in the comparison.

The paper presents a new technique for synthesizing the radiation pattern of an active linear phased array. The approach taken in the paper is to integrate the power response of the array over a spatial region of interest and force it to less than or equal to the desirable value. The closed form equation of the objective function is derived such that a numerical technique based on gradient search can be used to optimize the far-field patterns in a fast and efficient manner.