This paper investigates memory nonfragile mixed-objective output feedback robust model predictive control (OFRMPC) for a class of uncertain systems subjected to physical constraint, bounded disturbance, unmeasurable delayed state and possible controller fragility. By employing a delay-independent Lyapunov-Krasovskii function and linear matrix inequality (LMI) framework, novel sufficient conditions for the proposed memory non-fragile OFRMPC are derived to asymptomatically stabilize the closed-loop system with guaranteed H∞/H2 performance for all admissible polytopic uncertainties, external disturbance, state delay, and additive or multiplicative gain perturbation. A key technique for this controller is the online optimization of an infinite-horizon objective function followed by a memory output feedback control law based on the pre-specified offline state estimator using modified quadratic bounded conditions. Moreover, the input constraint and the recursive feasibility have been further guaranteed via additional LMI-based conditions. Finally, a numerical example is given to illustrate the effectiveness of the proposed OFRMPC approach.

Interval time-varying delay is common in control process, e.g., automatic robot control system, and its stability analysis is of great significance to ensure the reliable control of industrial processes. In order to improve the conservation of the existing robust stability analysis method, this paper considers a class of linear systems with norm-bounded uncertainty and interval time-varying delay as the research object. Less conservative robust stability criterion is put forward based on augmented Lyapunov-Krasovskii (L-K) functional method and reciprocally convex combination. Firstly, the delay interval is partitioned into multiple equidistant subintervals, and a new Lyapunov-Krasovskii functional comprising quadruple-integral term is introduced for each subinterval. Secondly, a novel delay-dependent stability criterion in terms of linear matrix inequalities (LMIs) is given by less conservative Wirtinger-based integral inequality approach. Three numerical comparative examples are given to verify the superiority of the proposed approach in reducing the conservation of conclusion. For the first example about closed-loop control systems with interval time-varying delays, the proposed robust stability criterion could get MADB (Maximum Allowable Delay Bound) about 0.3 more than the best results in the previous literature; and, for two other uncertain systems with interval time-varying delays, the MADB results obtained by the proposed method are better than those in the previous literature by about 0.045 and 0.054, respectively. All the example results obtained in this paper clearly show that our approach is better than other existing methods.

In practical engineering, the frequency splitting of Hemispherical Resonator Gyro (HRG) caused by uneven mass distribution seriously affects the precision of HRG. So, the inherent frequency is an important parameter of micro-Hemispherical Resonator Gyro (m-HRG). In the processing of hemispherical resonator, there are some morphological errors and internal defects in the hemispherical resonator, which affect the inherent frequency and the working mode of m-HRG, and reduce the precision and performance of m-HRG. In order to improve the precision and performance of m-HRG, the partial differential equation of the hemispherical resonator is solved, and the three-dimensional model using ANSYS software accurately reflected the actual shape is established in this paper. Then, the mode of hemispherical resonator in ideal state and uneven mass distribution state are simulated and analyzed. The frequency splitting mechanism of the hemispherical resonator is determined by calculation and demonstration, and the frequency splitting of the hemispherical resonator is suppressed by partial mass elimination. The results show that the absolute balance of energy can ensure the high-quality factor and the minimum frequency splitting of the hemispherical resonator. Therefore, during the processing of hemispherical resonator, the balance of mass should be achieved as much as possible to avoid various surface damage, internal defects and uneven mass distribution to guarantee the high-quality factor Q and minimum frequency splitting of hemispherical resonator.

The precision of the strapdown inertial navigation system (SINS) depended on the work precision of the gyroscope. However, many errors affect the precision of SINS even if the gyroscopes have perfect principles and structures. Before the application of the inertial navigation system (INS), the inertial components must be calibrated to ensure the performance of components, detect whether the precision of the inertial component satisfied the system, and compensate for the error of INS. According to the mathematical model of fiber optic gyroscope (FOG), we propose a multi-position iterative recursive calibration algorithm to compensate for the error of scale factor and installation of FOG. To guarantee the accuracy of the SINS, the error mathematical model of the FOG is established and compensated in the system. Finally, the calibration parameters of FOG are calibrated by the multi-position iterative recursive calibration (MPIRC) and the six-position method. The calibration results show that the accuracy of components calibration parameters of the MPIRC and the sixposition is similar, but the accuracy of SINS using MPIRC is higher than that using sixposition. (C) 2021 Society of Photo-Optical Instrumentation Engineers (SPIE)

According to the characteristics of spacecraft capturing noncooperative targets in orbit, an increment feedback controller based on nonlinear iterative sliding mode is presented. Firstly, the attitude tracking error equation is established, and then, an increment feedback control law based on bounded iterative sliding modes is proposed, which does not need to estimate the uncertain moment of inertia and external disturbances. For comparing, an adaptive sliding mode controller has been designed in the paper. Some numerical simulations have been given in the presence of spacecraft on-orbit capturing noncooperative target, and the simulation results show that the increment feedback controller has strong robustness to the unknown parametric variations and external disturbances and has a smaller control input torque in control process.

This paper focuses on the linear parameter varying (LPV) modeling and controller design for a flexible air-breathing hypersonic vehicle (AHV). Firstly, by selecting the measurable altitude and velocity as gain-scheduled variables, the original longitudinal nonlinear model for AHV is transformed into the LPV model via average gridding division, vertex trimming, Jacobian linearization, and multiple linear regression within the entire flight envelope. Secondly, using the tensor product model transformation method, the obtained LPV model is converted into the polytopic LPV model via high-order singular value decomposition (HOSVD). Third, the validity and applicability of the HOSVD-based LPV model are further demonstrated by designing a robust controller for command tracking control during maneuvering flight over a large envelope.

Because the accuracy of the existing airborne navigation is lacking in the polar region, it is difficult to ensure the safety and reliability of the aircraft when it is flying over the polar region. The integrated navigation system based on the inertial navigation technology uses multi-information fusion to assist collaborative navigation and obtain an indirect grid navigation algorithm that combines the azimuth navigation algorithm and the grid navigation algorithm to solve the existing problems. This paper analyzes the principle of the inertial navigation system in the polar region, the semiphysical simulation experiments are carried out by using the navigation theory and the background engineering, and the accuracies of the integrated navigation system of the indirect grid frame in the polar region and the integrated navigation system in the middle and low latitudes are consistent, which verifies the feasibility and effectiveness of the SINS/CNS/GPS integrated navigation system in the polar region. In addition, the paper provides the theoretical basis and the application of engineering to achieve the SINS/CNS/GPS integrated navigation system in the polar region.

基于一种新型的时滞分割法和互凸组合技术,借助于构造一个包含四重积分项的Lyapunov-Krasovskii泛函(UF),并利用新的积分不等式方法给出了LMI形式的时滞相关有界实判据;基于此给出了该系统非脆弱H∞控制器的设计方法,该方法不需要参数调节且易于实现;仿真结果表明,所推导的有界实判据和所设计的控制器具有很好鲁棒性和非脆弱性.

On the basis of the theory of electromagnetic wave propagation in monolayer construct of left-handed material(LHM) and right-handed material (RHM), a calculation method based on recurrence is proposed, this method can be used in the computation and forecasting of the absorbing efficiency of multi-layer materials. Then, the results are consistent with another derived from traditional transmission-line method. But compare to the later, the new calculation method is simpler and more direct. Furthermore, using in Structure consisting of LHM and RHM is also referred. At last, we use this model analyzes the effect by the LHM's electromagnetic parameter to absorption, from that, we obtain some useful conclusions. Our research results indicate that when LHM is combined with conventional RHM to form a LHM-RHM double-layer structure absorber, the reflection loss will be increased and the absorbing band will be widened. This indicates that the LHM is hopeful to be one of the wave-absorber composite materials, which has better absorbing effect.