Advanced Materials Research Vols. 383-390

Abstract: By means of power linkage chart method, the model of closed loop pumping system of concrete pump was set up and simulation was carried out in the Matlab. The results show that the hydraulic shock in the closed loop did not occur at the rapid commutation of piston pump and it actually happened when the concrete was pushed forward after compression. The main piston pump commutation is soft action and this shock can be eliminated effectively by means of “SN” control. Closed loop delivery system is used more widely in high volume concrete pumps and is featured by advantages like energy saving, smooth commutation and low hydraulic shock. In this paper, by means of power linkage chart method, the model of the system was set up and dynamics equations set of the system was obtained. A simulation model was set up by means of simulation toolkit in Matlab language – Simulink, in order to have simulation study of commutation shock of the pumping system and shock due to pushing load and obtain the transient performance of model in time domain.

Abstract: In this paper, a sliding mode controller is developed based on the modified rodrigues parameters. Modified rodrigues parameters can avoid the singularity in kinematic equations and realize less parameters setting. Finally, the numerical simulation results show that the method is effective.

Abstract: This paper presents a real-time optical flow algorithm for a vision-based guidance of an unmanned aerial vehicle (UAV). The optical flow algorithm detects a moving target, and obtains the optical position and optical flow vectors of the target from the image sequence. Then, a vision-based guidance of the UAV is designed to follow the moving target. Additionally, the control law of the imaging seeker uses visual information from the image sequence for target tracking. The method was tested on a 3 degree of freedom (3DOF) dual-rotor UAV with a video camera and the result proved the effectiveness of this method.

Abstract: This paper deals with an empirical dynamic model for decoupling control of the variable speed refrigeration system (VSRS). To cope with inherent complexity and nonlinearity in system dynamics, the model parameters are first obtained based on experimental data. In the study, the dynamic characteristics of indoor temperature and superheat are assumed to be first-order model with time delay. While the compressor frequency and opening angle of electronic expansion valve are varying, the indoor temperature and the superheat exhibit interfering characteristics each other in the VSRS. Thus, each decoupling model has been proposed to eliminate such interference. Finally, the experiment and simulation results indicate that the proposed model offers more tractable means for describing the actual VSRS comparing to other models currently available.

Abstract: A voltage control strategy of the converter inverter-stage is proposed for the variable speed direct drive wind power system which consists with the two stage matrix converter (TSMC) and the permanent magnet synchronous generator (PMSG). In this control strategy, the inverter-stage voltage is controlled by the adjusted of inverter-stage modulation ratio M. For two cases, which is strong wind speed and weak wind speed, the ways that is decrease M and increase M are used and obtain the wide wind speed capture range. The resulted of simulation and experiment show that this way can make the voltage stabled. The performance of the converter implement this control strategy is still as same as the dual PWM converter and the wind power system preserve the feature of the wide wind speed capture range. So this way is effective and feasible to some extent.

Abstract: The accumulation course angle error of inertial navigation system will decrease the accuracy and reliability of an geomagnetism aided inertial navigation system using a geomagnetic contour matching algorithm. To improve the matching accuracy, the matching track and true track should be as parallel as possible. An improved geomagnetic matching algorithm is presented by introducing rotation angle search technique. To reduce the computation burden, improve operation efficiency and reduce false matching probability, a new search area determination method is proposed, which redefines the search region and reduces the search range. Simulation results demonstrate the effectiveness of the proposed algorithm and the improvement in the matching accuracy.

Abstract: Signal Quality Monitoring (SQM) proposes to detect anomalous Global Navigation Satellite System (GNSS) signal distortions primarily through the using the multi-correlator receivers. These receivers employ three or more correlator pairs per channel-each slaved to tracking pairs. Then the measurements from each channel are transformed to form detection metrics. However, previously such some metrics were only simple algebraic combinations of the measurements and did not describe truly the characteristics of the correlation peak. This paper introduced a metric which uses measurements of each channel to fit the quadratic model with least-squares method to monitor the GNSS signal.

Abstract: Kernel-based density estimation technique, especially Mean-shift based tracking technique, is a successful application to target tracking, which has the characteristics such as with few parameters, robustness, and fast convergence. However, classic Mean-shift based tracking algorithm uses fixed kernel-bandwidth, which limits the performance when the target’s orientation and scale change. An Improved adaptive kernel-based object tracking is proposed, which extend 2-dimentional mean shift to 3-dimentional, meanwhile combine multiple scale theory into tracking algorithm. Such improvements can enable the algorithm not only track zooming objects, but also track rotating objects. The experimental results validate that the new algorithm can adapt to the changes of orientation and scale of the target effectively.

Abstract: Wind as a renewable energy, is typical of clean energy, and wind power generation has good social and environmental benefits, which has developed rapidly in worldwide. In this paper, the problems of China's wind power industry and the world wind power industry experience are discussed. The distribution of resources for wind energy, wind energy resource assessment, monitoring and forecasting system, wind industry, policy influencing factors are detailed analysis, and based on China conditions for its development were discussed.

Abstract: A new design technique based QFT and Pade Approximation for tracking control has been proposed. QFT controller attempts to place all plant poles within a specified region on the s-plane to guarantee the desired closed loop performance. As for the robust dynamic tracking performance, a new algorithm to design the feedforward controller based pade approximation has been prescribed in the case that the preview information of the desired output is not available. Simulation results for flight simulator show that the proposed approach is effective, successful and applicable.