Applied Mechanics and Materials Vols. 241-244

Abstract: The rationality of transmission line responses, tower responses, etc., are determined by the computed wind loads, which are directly correlated with the free-stream turbulences that generated at different ground roughness conditions, different terrains, etc.. Accounting for this problem, the flow fields around transmission line conductor LGJ630/45 are computed by solving Navier-Stokes equations to study the influence of Tis (turbulence intensities) onto wind load characteristics. The results show that, the peak-values of power spectrum density (PSD) results of both lift and drag are obviously influenced by TIs, while their corresponding frequencies are kept the same at different TIs; with the increase of Tis, the time-averaged value of conductor drag decreases nonlinearly and monotonically. Thus, given the influence of TIs onto wind loads, field observed free-stream values should be used as inputs for numerical simulations, and then the obtained wind loads can be adopted to accurately simulate transmission line gallopings and windage yaws.

Abstract: The extended reach drilling (ERD) is being adopted widely as an effective and economical way of developing oilfields in China. But it also brought a series of technical difficulties because of its own characteristics. Some progresses were made after several years of hard work in China about Hydraulics for extended reach drilling, which included cuttings transport models and rules, precise model of circulating system pressure loss calculation, hole cleaning calculating models and monitoring method, hydraulic extended limit calculation model and analysis, hydraulics design and optimization method for ERD. Based on the above studies, the author finally developed a system of hole cleaning monitoring and hydraulics design and its risk analysis which could provide theoretical support and useful tool for engineering design and risk assess before drilling. These researches are helpful to ERD and have enriched the hydraulic theory of ERD.

Abstract: Accelerometer is the important sensor of MEMS inertial sensors and is applied in many occasions. A three dimension model is designed to accomplish rotary motion in 3D space and the model is introduced to the computer input system to enhance the functions of the computer input system. In order to indicate the feasibility and effectiveness, a Demo platform with AVR controller is designed to control the rotary motion of accelerometer solid model.

Abstract: The hydraulic transmission control system in the metal forming equipment makes the piston rod freedom movement. This paper introduces that using PLC but not original relay contact to realize the free movement of the piston rod. Adopting PLC as the control system, the automation degree of the piston rod will be improved. And also ensure the piston rod has a high reliability when it has continuously acting, the system will meet the requirements of the general and flexibility. This paper analyzes the action of the hydraulic system. Subsequently, the methods of the hardware selection and the software program design were illustrated.

Abstract: The active magnetic bearing system has been studied for long period. Comparing with long research history, the AMB application into industrial field is shown slowly for various causes. One of primary factor is to make up exclusive controller which can generate fast linear current output. Thus, this paper developed the exclusive AMB controller mounted high speed DSP which can operate so fast control calculation that improve system response ability. Especially, to consider the fusion of AMB system and control software, the development is conducted in HILS system with dSPACE from the beginning. Although HILS system is adopted, the developed ABM controller simplified the whole system and could make up optimized control algorithm promptly by measuring and applying the system gain and characteristics of them monitored by the HILS system in real time.

Abstract: Permanent magnet synchronous motor (PMSM) servo system has been widely used in various fields. To improve its performance, the hardware and software of PMSM servo system based on the advance DSP of TMS302F28335 were designed in this paper. The principle of DTC for PMSM and stator flux estimator used LPF instead of pure integrator are introduced. The simulation and experimental results show that the designed servo system can achieve good dynamic, static performance and good robustness.

Abstract: An extended high gain state and perturbation observer combined with feedback linearization was applied in drag tracking for Mars entry longitudinal guidance. The observer estimates the drag, the drag rate and the perturbation due to model uncertainty and disturbance for drag tracking. Mars entry simulation was performed to assess the performance of the adaptive guidance law. The results demonstrate that the proposed guidance law is robust to model error, and can recover the ideal performance of the feedback linearization control.

Abstract: This paper describes on the issue about the deployment and position of the space mechanism under the vacuum, low temperature environment on the ground. Firstly, for the technical requirement of the deployment mechanism, the authors put forward deployment mechanism project, conduct the structural design. Secondly, focused on the hardware design and the software design of the control system, the control system using master and slave CPU structure of the upper and lower computer, and the rotatable control using the teach mode. Finally, the authors conduct the deployment device performance test under the vacuum, low temperature environment.

Abstract: The drilling efficiency can be improved effectively by controlling the lunar regolith sampler always in the resonance state. But the dynamical modeling of the sampler-regolith system is difficult to obtain and time varies when the sampler is in different depth in the lunar regolith. For the nonlinear time-varying system of the dynamic modeling of the sampler in drilling, we present a method of the vibration frequency fuzzy adaptive control based on the dynamic prediction by using the RBFNN. The Radial Basis Function (RBF) neural network with a FIR filter in series is used to predict the resonant frequency dynamically and decrease the overshoot. And the fuzzy adaptive control is used to calculate the sweeping frequency bandwidth with the input of the amplitude and variation. The simulation results have verified the effectiveness of the control strategy. The experimental results show that the control algorithm can improve the drilling depth, drilling efficiency and the discarding efficiency effectively.

Abstract: A new real-time control method for software CNC based on PC is proposed, and the data exchange methods are given. Both external and system clock interrupt are adopted as interpolation cycle to make up software CNC on PC. The data between the front procedures, interpolation module, and background procedures, application module, is exchanged by WDM. The method is verified in experiment, and the resolves show that the speed control and the interpolation operator are right, and whole software CNC is significantly improved.