Applied Mechanics and Materials Vols. 511-512

Abstract: This paper presents an adaptive nonlinear controller equipped with a friction estimator for a 6 degree of freedom (DOF) parallel manipulator-steward platform. With the aid of direct adaptive technique and control Lyapunov function method, an adaptive controller is designed to complete the globally adaptive stability of the closed-loop system. The stabilized conditions and corresponding proof are also presented, and the selection method of the controller parameters is proposed. Simulation results are demonstrated in support of the proposed control scheme.

Abstract: Strong Electromagnetic Pulses (EMP) as a new idea weapon has caused many effects like malfunctions, performance degradation, interferences, and destructions in electronic and electrical systems. EMP coupling model research is the foundation of effect evolution and protection. In this paper, a new modeling method on the base of combination system identification theory and Volterra series algorithm was utilized to analyze the electromagnetic coupling process from an external field to an inner electric system. First, we will analyze the theory foundation of non-parameters model evolution. And then, using input and output test data, we presented commonly Voleterra series expression of EMP electromagnetic coupling model. Then, we analyze coupling models several important characteristics in detail. Finally, we approach High Order Spectrum algorithms to identify Volterra kernel functions. Theoretical results show that the Volterra kernel function will be used as an efficient method in EMP coupling model research and can apply this method to character the nonlinear behavior of the EMP electromagnetic coupling. The model described above was assigned under certain assumptions, moreover describes the effects in theory only and does not consider the time variation of the parameters of the system. From this reason it appears as more convenient to characterize the electromagnetic coupling process, by a more universal mathematical approach.

Abstract: Parameters of theodolite measuring motor will vary with duty conditions bringing about aiming control system chaotic, which is harmful for the aiming system and the aiming result. In order to be close to reality, considering that the aiming system is under time-varying load and inside disturbances, the dynamic model was established and analyzed. The existence of chaos was proved. Due to terminal sliding control with good robustness, fast dynamic response, finite time convergence and high tracking precision, PI terminal sliding structure and control strategy were given, and the system stability was analyzed. The chaotic orbits of aiming motor system were stabilized to arbitrary chosen fixed points and periodic orbits by means of sliding mode method. Simulation results show that PI terminal sliding mode control can realize the stability and accuracy of aiming motor control system, and overcome the negative influence of the chaos for the aiming system.

Abstract: In order to make the moon patrol car get the accurate test result, the active suspension method with controlling the force circuit directly is used. In the paper, the system model is established and delay time problem and the parameter uncertainty are dealt in it. To improve the control precision, location control is used on the basis of the force circuit and to solve the interference problems, the uncertainty and the time delay, the controller is designed. Through the simulation test, the controller has a good effect of the problems.

Abstract: Combining with the principle of permanent magnetic and electromagnetic suspension, we can establish its mathematical model. Maglev system is a typical nonlinear system. Simulation model is built based on fuzzy control in matlab by combining the advantages of fuzzy control. By comparing the simulation results with PID, the simulation results show that fuzzy control can make the magnetic levitation system has better dynamic performance and steady-state performance.

Abstract: Due to LNG liquid density is uneven, traditional LNG tank bottom discharge way produces layering and rolling phenomenon, in this paper, the way of charging LNG liquid in a circle is put forward. 30,000 square tank is taken as an example, the nozzle jet angle and nozzle number range are calculated. Through the selection of reasonable nozzle jet angle and nozzle number, the new charged LNG liquid flows circularly and mixes with original liquid automatically, the probability of layering and rolling phenomenon reduced greatly.

Abstract: The global navigation satellite systems (GNSS) is used more and more widely in military and civilian, but because of low sending power of GNSS signal, and other weakness, the safety and protection related issues have attracted wide attentions. However, most literatures about this were just qualitative enumeration or only focused on the navigation performance itself. This work studied this question from the view of the main materiel system that GNSS served for. We analyzed the impacts of GNSS receiver’s safety & protection ability on the operational utility of main materiel system based on a mathematical model. First of all, a mathematical function which contains several protection related parameters was used to describe the issues, followed with detail quantitative methods for those parameters. Then a case study was shown to demonstrate the application of the model proposed before. Based on the case study, it appears that the method has great potential and applicability to safety & protection ability analysis of GNSS.

Abstract: The air-conditioning system is discussed in an office building of Yunlong demonstration area, located in the northwest of Zhuzhou city in Hunan province. The climate of Zhuzhou is subtropical monsoon climate and it is highly humid all the year, hot and humid in the summer. The air-conditioning system used the ground source heat pump is the cold and heat source of temperature and humidity independent control system, which has improved the efficiency of the energy use. And the use of the soil thermal energy has improved the energy efficiency of the system.

Abstract: This paper proposes a guarantee steady state observation precision and pole assignment precision of the feedback controller, the basic idea is to introduce state observer can easily get dc linear motor speed and acceleration condition, state space pole assignment can pass, select the appropriate zero pole can improve the control performance of the motor. Based on the observation of the gain matrix can compensate for the steady-state error of the dc linear motor. Based on the observation of the gain matrix can compensate for the steady-state error of the dc linear motor. Matlab simulation results show that the control algorithm is compared with the traditional pole assignment, it is able to quickly and accurately follow the speed of the motor. The system has better dynamic and steady-state performance, and its characteristic of the closed-loop system robustness is stronger.

Abstract: In this paper, the attention is focused on the optimization of a particular class of nonlinear systems. The optimum linear solution is not the best one so the problem of determining a nonlinear state feedback optimal control law with quadratic performance index over infinite time horizon is considered. It isn't an easy task and the most discouraging obstacle is the resolution of the Hamilton-Jacobi equation. Thus our contribution, based on the use of the tensor product and its algebraic laws, provide analytic solutions of the studied optimal control problem. The polynomial state feedback solution is computed through a numerical procedure. A numerical example is treated to illustrate the proposed solutions and some conclusions are drawn.