Applied Mechanics and Materials Vols. 271-272

Abstract: For the linear time-invariant model of a twin-rotor helicopter, a new control scheme is proposed in the presence of actuator faults, environmental disturbances and modeling errors. Using the Lyapunov stability theorem, the system with proposed adaptive controller is proved to be stable, and the tracking error tends to zero asymptotically. Simulation results prove the effectiveness of this method.

Abstract: With the continuous development of industrial automation, robots are applied to various fields of industry increasingly, and the robot pose accuracy become an important issues. Through the establishment of the robot parameterized virtual prototype model, the error of bar length, joint angle and joint space have been taken into account, and the Monte Carlo sampling method is used to process a number of simulation analysis. The reliable probability which is given within the error limits is calculated, and finally through sensitivity analysis, the conclusion is drawn that different error factors influent the robot end error differently, which have a certain significance for the allocation of the manufacturing tolerances of the robot and trajectory planning.

Abstract: This paper begins with a brief description of the prevailing standby methods and their drawback of having to rely on the municipal mains supply at all times and wasting electrical energy. It then proceeds to elaborate on the energy conservation principle of the optical energy wait-up technology, which has been granted a national utility model patent (No. ZL 2011 2 0489460.7). The elaboration is focused on the working principle and process of the changeover of the power supply of the device from the grid to an optical battery while it is in standby mode, as well as on the basis for the choice of components. This utility model consumes energy in milliwatts and has practical value for energy conservation and emission reduction. Its commercialization is expected to contribute significantly to energy conservation in the entire society.

Abstract: In the supersonic engine inlet, Mach Reflection probably appears when a supersonic flow goes through the symmetric wedges, causing a great total pressure loss. A single pulsed laser energy deposition leads a decrease of the Mach stem height and reduces the total pressure loss. By solving the two-dimensional RANS equations, with the condition of symmetric wedges at 22 degrees, and the free stream Mach number 3.45, influences of the deposition location and the magnitude of pulsed laser energy in Mach Reflection are investigated. The results indicate that when laser energy rises from 70mJ to 270mJ, the height of Mach stem changes and a vale value is obtained. The deposition position is also optimized.

Abstract: Laser forming of sheet metal offers the advantages of requiring no hard tooling, no spring back and no external force. Thus this technology reduces cost, increases flexibility and accuracy. Laser forming is a complicated and transient thermo-mechanical process involving elastic and plastic strain dependent on time history. How to control and enhance the accuracy of the laser forming attracts much attention. This paper put forward a new strategy to control and reduce the edge effects in laser forming. Numerical simulations and experiments were also carried out to validate the presented strategy.

Abstract: The assembly variation of Aeronautical Thin Walled Structure (ATWS) with automated riveting is inevitable. The deformations of drilling, riveting and releasing are ralated to the final assembly variation. This paper represents a new method for deformation analysis of ATWS with automated riveting. Drilling deformation is modeled by the relationship among deflexion, strain and stress, riveting deformation is modeled by uilibrium equation, and releseaing deformation is modeled by releasing force. The comparison between computing result and expriment proves that the purposed deformation analysis method can solve the problem for ATWS automated riveting efficiently.

Abstract: Energy consumption is one of the important evaluating indicators for walking robots. In this paper, the kinematics modeling of quadruped robot with trot gait was analyzed firstly. And then the dynamics modeling was analyzed, which considering periodic contact force between foots and ground during walking, and considering the elastic elements. Finally, the total energy consumption of walking robot during whole gait cycle was derived based on the dynamic model. The specific resistance was proposed to evaluate energy efficiency of quadruped robot with trot gait, and the relationship between specific resistance and gait parameters was presented, which will be used to analyze the energy efficiency and influencing factors, and then determine the reasonable gait parameters.

Abstract: This paper presents a chess-playing robot and its control system based on SERCOS. Thanks to Windows NT operating system and RTX real-time extension, the control system is excellent in real-time property. The whole system, supported by a standard IPC hardware platform and a modularized architecture of system software, is open-ended and expansible. In addition, the chess-playing software makes a contribution to the excellent interaction between players and the chess-playing robot.

Abstract: When applying Parameter Discriminant Analysis (PDA) in extracting features of radar target High-Resolution Range Profile (HRRP), the construction of scatter matrices relies on the assumption that HRRPs in all classes satisfy the Gaussian distribution with the same covariance matrix. However, the distribution of HRRP is actually complex. In order to tackle this problem, a radar target recognition approach based on nonparametric feature analysis and back cloud model is proposed in this paper. Compared with PDA, nonparametric feature analysis (NFA) estimates the contribution of the K nearest neighbors (KNN) points to calculate the between-class scatter matrix. NFA makes use of class boundary information and relaxes the requirement of Gaussian distribution assumption in PDA. Moreover, back cloud model better describes the complex distribution of the HRRP NFA subspace due to the representation of signal’s randomness and fuzziness. Simulation results based on a HRRP dataset of five aircraft models demonstrate the effectiveness of the proposed approach.

Abstract: Many research projects are involved in environmental monitoring in recent years. However, most existing studies are interest in the outdoor natural environment monitoring. Few of them focus on the indoor monitoring. This paper presents a system based on wireless sensor network (WSN) for granary monitoring including grain temperature and grain moisture content monitoring. To our best knowledge, this is the first time to provide a system based on WSN, which can measure the grain moisture content on line. The overall system architecture is described in detail. Besides, the wireless communication protocol and the network deployment are introduced.