空—地制导武器发射前的载机控制研究

载机的控制主要包括导航控制和姿态稳定控制两个部分。针对空—地制导武器发射前的载机控制, 分析了导航控制方式和构成姿态控制的纵向与横侧向通道。研究了空—地制导武器发射前栽机的导引控制率设计以及航向、俯仰、高度、速度等的控制规律。文章最后探讨了采用半实物仿真的方法在地面对其进行实验、验证的方式和方法。

Credibility and Security of Weighing System for Large Structure Object

The weighing system designed for large structure object is mainly composed of three parts. The part of hydraulic system is made up of hydraulic cylinders, high pressure hydraulic hoses and electric pumps; the part of computer controlling system comprises pressure sensors, displacement sensors, data acquisitions, RS 485 network and the computer controlling model; the part of loading system is composed of the fulcrum structure and the concrete girder. The measurement principle and composition of the weighing system are discussed in this paper. Credibility and security of the weighing system are fully considered during the design phase. The hydraulic system is controlled by pilot operated check valves in case of the sudden loss of system pressure. The states of all gauges and RS485 network are monitored by computer controlling system functioning in different modules. When the system is running incorrectly, it will be switched to manual mode and give alarm. The finite element method is employed to analyze fulcrum structure so that the system has enough intensity to be lifted. Hence the reliability of the whole system is enhanced.

Hydraulic cylinder control of injection molding machine based on differential evolution fractional order PID

Injection molding machine,hydraulic elevator,speed actuators belong to variable speed pump control cylinder system.Because variable speed pump control cylinder system is a nonlinear hydraulic system,it has some problems such as response lag and poor steady-state accuracy.To solve these problems,for the hydraulic cylinder of injection molding machine driven by the servo motor,a fractional order proportion-integration-diferentiation(FOPID)control strategy is proposed to realize the speed tracking control.Combined with the adaptive differential evolution algorithm,FOPID control strategy is used to determine the parameters of controller on line based on the test on the servo-motor-driven gear-pump-controlled hydraulic cylinder injection molding machine.Then the slef-adaptive differential evolution fractional order PID controller(SADE-FOPID)model of variable speed pump-controlled hydraulic cylinder is established in the test system with simulated loading.The simulation results show that compared with the classical PID control,the FOPID has better steady-state accuracy and fast response when the control parameters are optimized by the adaptive differential evolution algorithm.Experimental results show that SADE-FOPID control strategy is effective and feasible,and has good anti-load disturbance performance.

Hybrid force control of astronaut rehabilitative training robot under active loading mode

In order to mitigate the effects of space adaptation syndrome(SAS) and improve the training efficiency of the astronauts, a novel astronaut rehabilitative training robot(ART) was proposed. ART can help the astronauts to carry out the bench press training in the microgravity environment. Firstly, a dynamic model of cable driven unit(CDU) was established whose accuracy was verified through the model identification. Secondly, to improve the accuracy and the speed of the active loading, an active loading hybrid force controller was proposed on the basis of the dynamic model of the CDU. Finally, the actual effect of the hybrid force controller was tested by simulations and experiments. The results suggest that the hybrid force controller can significantly improve the precision and the dynamic performance of the active loading with the maximum phase lag of the active loading being 9° and the maximum amplitude error being 2% at the frequency range of 10 Hz. The controller can meet the design requirements.

A Review of Aftershock Mechanism Research

In this paper,research of aftershock mechanisms is reviewed,including heterogeneity of medium and stress,mechanical loading,fluid intrusion and stress corrosion,and ratestate dependence.Previous studies have indicated that the heterogeneity of media and stress is the basic premise of aftershocks generated.From the point view of mechanics,transient creep and afterslip can explain the decay of aftershocks in a short time after a mainshock and the relaxation of stress tends to interpret the characteristics of long-term aftershocks.Fluid intrusion and stress corrosion control the evolution process of the aftershocks under certain conditions.The interaction between the faults perturbed by the mainshock always exists during the aftershock activities.All kinds of models and the theories want to comply with the two basic power-law relationships---the G-R law and Omori law to some extent.

Load Frequency Control of a Two Area-Power System with Non-reheat Turbines by SMC Approach

Load frequency is an important issue in power system operation and control. In this paper, load frequency control for suppression frequency deviation in an interconnected power system with nonlinearities using SMC （sliding mode control） is studied. The governor dead band and GRC （generation rate constraint） is considered in this article. Digit simulations for both two areas and three areas power system with non-reheat turbines are provided to validate the effectiveness of the proposed scheme. The results show that, the robustness of the control method under parameters variation and different load disturbances with the SMC technique.

Nonlinear Rolling Control Technology of Liquid Launch Vehicle Based on Single Engine

New program was proposed in LM-6 rolling control technology that using high-pressure staged combustion gas. Launch vehicle rolling control by just one engine was realized. Under the limit of the rolling control moment of the launch vehicle, a new attitude dynamic model is established. Interference source and how to reduce the effect was analyzed, and method of designing a pre-compensated robust controller was proposed. Simulation and flight resuits showed that the attitude dynamic model established and the pre-compensation robust controller proposed in this paper could solve the key problems with a strong coupling attitude controller, and realize high quality and high reliability control in wind areas, and improve the capability of the launch vehicle.

Improving the Performance of an Electro-Hydraulic Load-Sensing Proportional Control Valve

The paper deals with the simulation and the experimental verification of the hydraulic behavior of an electro-hydraulic load-sensing proportional control valve. An innovative CAE （computer aided engineering） methodology, developed combining CFD （computational fluid dynamics） simulations with lumped and distributed numerical modeling, is firstly introduced and tailored by comparing the numerical results with measurements coming from an experimental campaign performed for a wide range of pressure loads and metered flow rates. Then, both the reliability and the limits of the numerical approach are highlighted through a detailed numerical vs. experimental comparison, involving the pressure of the main hydraulic lines, the flow rate through the first section and the local compensator displacement. Finally, the CAE methodology has been applied for assessing the internal ducts hydraulic permeability and the local compensator spring pre-load influence on the control valve metering curves. At the end of this analysis, an optimized design configuration, featuring a maximum controlled volumetric flow rate increased of more than 25%, has been proposed.

Autonomous energy efficient wheel loader research at TUT

Future worksites will be occupied by different level of automation work machines. How these machines are working individually and how a fleet of these machines cooperates will be in focus of research and development work in the future. In this paper the studied off-road vehicle is a wheel loader. It can be controlled manually, remotely or autonomously. The control strategy of autonomous wheel loader is consisting of, e.g., static and dynamic mapping, path planning, obstacle observation and avoidance. In the autonomous machines and also in machines where operator assistance system is active the situational awareness is the key research field. Power management in hydraulic work machines are still active fields of research. Multiple architectures and configurations have been suggested concerning this area. In addition, implemented solutions that consider an entire machine are rarely presented. This paper introduces the research work of the control systems which are minimising the fuel consumption.