Trim State Discovery for an Adaptive Flight Planner

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83601/1/AIAA-2010-416-783.pd

Modeling of Acceleration Influence on Hemispherical Resonator Gyro Forcing System

Acceleration adds negative effect to Hemispherical Resonator Gyro (HRG) output; therefore, it is important to model the influence and then make necessary compensations, accordingly. Based on the elastic thin-shell theory under the Kirchhoff-Love assumption, the acceleration influence on HRG forcing system is modeled and then schemes for incentive are suggested. Firstly, the dynamic model of resonator is introduced. Then, inertial load and electrostatic force are calculated to obtain the deformation of resonator. At last, schemes for pickoff incentive are proposed to weaken the effect of acceleration on HRG forcer. The simulation results illustrate that acceleration has negative effects on the exciting confidents of forcers and the proposed scheme can eliminate the acceleration influence on forcing system

White spot syndrome virus: an overview on an emergent concern

Viruses are ubiquitous and extremely abundant in the marine environment. One of such marine viruses, the white spot syndrome virus (WSSV), has emerged globally as one of the most prevalent, widespread and lethal for shrimp populations. However, at present there is no treatment available to interfere with the unrestrained occurrence and spread of the disease. The recent progress in molecular biology techniques has made it possible to obtain information on the factors, mechanisms and strategies used by this virus to infect and replicate in susceptible host cells. Yet, further research is still required to fully understand the basic nature of WSSV, its exact life cycle and mode of infection. This information will expand our knowledge and may contribute to developing effective prophylactic or therapeutic measures. This review provides a state-of-the-art overview of the topic, and emphasizes the current progress and future direction for the development of WSSV control strategies

UAV Robust Strategy Control Based on MAS

A novel multiagent system (MAS) has been proposed to integrate individual UAV (unmanned aerial vehicle) to form a UAV team which can accomplish complex missions with better efficiency and effect. The MAS based UAV team control is more able to conquer dynamic situations and enhance the performance of any single UAV. In this paper, the MAS proposed and established combines the reacting and thinking abilities to be an initiative and autonomous hybrid system which can solve missions involving coordinated flight and cooperative operation. The MAS uses BDI model to support its logical perception and to classify the different missions; then the missions will be allocated by utilizing auction mechanism after analyzing dynamic parameters. Prim potential algorithm, particle swarm algorithm, and reallocation mechanism are proposed to realize the rational decomposing and optimal allocation in order to reach the maximum profit. After simulation, the MAS has been proved to be able to promote the success ratio and raise the robustness, while realizing feasibility of coordinated flight and optimality of cooperative mission

Research on Dynamic Weapon Target Assignment Based on Cross-Entropy

The weapon target assignment (WTA) is a classical problem of defense-related applications which is proved to be a NP-complete problem. In this paper, a practical and available dynamic weapon target assignment (DWTA) formulation is given which incorporates two meaningful and conflicting objectives, that is, minimizing weapon costs and maximizing combat benefits. As we know, heuristic methods have some shortcomings such as slow convergence speed and local optimum in solving the nonlinear integer optimization problem. To this end, a novel DWTA algorithm based on cross-entropy (CE) method is introduced, where the resources requirement condition for targets is taken into consideration. The CE method associates an estimation problem with the DWTA optimization problem, and then, the estimation problem is transformed into a convex optimization problem. The Karush–Kuhn–Tucker conditions are applied to solve the convex optimization problem, and the iteration formulas to find the optimal solution are deducted. Furthermore, in order to verify the performance of CE method in dealing with the DWTA problem, several simulations in different combat scenarios are implemented. The results reveal that, compared with the benchmark heuristic and Monte-Carlo (MC) methods, there are some notable advantages in solving the DWTA problem based on CE method with regard to the solution quality and time consumption

Standing Wave Binding of Hemispherical Resonator Containing First–Third Harmonics of Mass Imperfection under Linear Vibration Excitation

Due to complicated processing technology, the mass distribution of a hemispherical resonator made of fused silica is not uniform, which can affect the azimuth of the standing wave of a resonator under the linear vibration excitation. Therefore, the analysis of standing wave evolution of a resonator with mass imperfection under linear vibration excitation is of significance for the improvement of the output accuracy of a gyroscope. In this paper, it is assumed that the resonator containing the first–third harmonics of mass imperfection is excited by horizontal and vertical linear vibration, respectively; then, the equations of motion of an imperfect resonator under the second-order vibration mode are established by the elastic thin shell theory and Lagrange mechanics principle. Through error mechanism analysis, it is found that, when the frequency of linear vibration is equal to the natural frequency of resonator, the standing wave is bound in the azimuth of different harmonics of mass imperfection with the change in vibration excitation direction. In other words, there are parasitic components in the azimuth of the standing wave of a resonator under linear vibration excitation, which can cause distortion of the output signal of a gyroscope. On the other hand, according to the standing wave binding phenomenon, the azimuths of the first–third harmonics of mass imperfection of a resonator can also be identified under linear vibration excitation, which can provide a theoretical method for the mass balance of an imperfect resonator

Modeling of Acceleration Influence on Hemispherical Resonator Gyro Forcing System

Acceleration adds negative effect to Hemispherical Resonator Gyro (HRG) output; therefore, it is important to model the influence and then make necessary compensations, accordingly. Based on the elastic thin-shell theory under the Kirchhoff-Love assumption, the acceleration influence on HRG forcing system is modeled and then schemes for incentive are suggested. Firstly, the dynamic model of resonator is introduced. Then, inertial load and electrostatic force are calculated to obtain the deformation of resonator. At last, schemes for pickoff incentive are proposed to weaken the effect of acceleration on HRG forcer. The simulation results illustrate that acceleration has negative effects on the exciting confidents of forcers and the proposed scheme can eliminate the acceleration influence on forcing system

Identification and Compensation Method of Unbalanced Error in Driving Chain for Rate-Integrating Hemispherical Resonator Gyro

The accuracy of the signal within a driving chain for the rate-integrating hemispherical resonator gyro (RI-HRG) plays a crucial role in the overall performance of the gyro. In this paper, a notable and effective method is proposed to realize the identification and compensation of the unbalanced error in the driving chain for the RI-HRG that improved the performance of the multi-loop control applied in the RI-HRG. Firstly, the assembly inclination and eccentricity error of the hemispherical resonator, the inconsistent metal conductive film layer resistance error of the resonator, the coupling error of the driving chain, and the parameter inconsistency error of the circuit components were considered, and the impact of these errors on the multi-loop control applied in the RI-HRG were analyzed. On this basis, the impact was further summarized as the unbalanced error in the driving chain, which included the unbalanced gain error, equivalent misalignment angle, and unbalanced equivalent misalignment angle error. Then, a model between the unbalanced error in the driving chain and a non-ideal precession angular rate was established, which was applicable to both single channel asynchronous control and dual channel synchronous control of the RI-HRG. Further, an unbalanced error identification and compensation method is proposed by utilizing the RI-HRG output with the virtual precession control. Finally, the effectiveness of the proposed method was verified through simulation and experiments in kind. After error compensation, the zero-bias instability of the RI-HRG was improved from 3.0950°/h to 0.0511°/h. The results of experiments in kind demonstrated that the proposed method can effectively suppress the non-ideal angular rate output caused by the unbalanced error in the driving chain for the RI-HRG, thereby further improving the overall performance of the RI-HRG

Trim State Discovery with Physical Constraints

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140604/1/1.C032619.pd