Applied Mechanics and Materials Vols. 128-129

Abstract: This paper proposes the modified projective synchronization of uncertain chaotic systems with unknown parameters via active adaptive sliding mode control (AASMC). The disturbances are considered both in the drive and the response system. The bounds of the disturbances are unknown. The adaptive updating laws are designed to tackle the unknown parameters. Moreover, the robustness and stability of the proposed AASMC is proved by the Lyapunov stability theory. Some numerical simulations are given to demonstrate the robustness and efficiency of the proposed scheme.

Abstract: There are two ways of excitation on steel-string sensor—high-voltage plucked excitation or low-voltage scanning frequency excitation. But both of them have disadvantages. The disadvantages of high-voltage plucked excitation are that it has a large damage to sensor, the signals got through this way attenuate fast, and measurement accuracy of the signals is poor. On the other hand, low-voltage sweeping excitation scans a long time and signals got though this way are hard to catch. This paper proposes a kind of feedback type low excitation method, which is pre-excite a sensor with a lower voltage on plucked vibration, and use vibration frequency got from this way as output of the excitation driver to vibrate the sensor for the second time. Because the feedback signal frequency is approximate to the real one, the string can reach a resonance state in a very short time. The optimal excitation strategy is verified by a new designed exciting and measuring circuit. It is confirmed that resonance amplitude can be larger in a shorter excitation time by this way, and result in an enhanced anti-interference ability, reduced the cost of signal processing circuit, increased available measuring time and improved the accuracy of frequency measurement.

Abstract: Concerning the effect of the parameter uncertainty caused by environmental temperature, we present a robust control algorithm for the fiber optical voltage transformer (FOVT) to achieve optimized dynamic performance. The principle of the FOVT based on closed-loop detection is analyzed and the system model is established. Based on the system model and the optimized dynamic performance index, the robust controller is investigated to suppress the effect of the forward gains variation. Furthermore, we give a design criterion in terms of linear matrix inequality (LMI) for the proposed control. Finally, the experimental results show that the control has strong robustness against parameter uncertainty for improving the dynamic performance of the FOVTs.

Abstract: There are problems with the tailpipe hook when the car is in durability test. In the paper, the exhaust system vibration analysis model is built first. It is found that the constraint force on the tailpipe hook which is cracked is bigger and the local stiffness is lower according to the frequency response analysis. After the structure optimization, the stiffness of the tailpipe hook is strengthened. Both the comparative analysis and idling test show that the optimized hook could explicitly reduce the vibration of the exhaust system which transfers to the car floor and improve the fatigue life of the exhaust system. The optimization method could be used for the similar fatigue problems.

Abstract: Regarding the cyclostationary of of amplitude-modulated signals, a method for extracting cyclostionary statistics of amplitude-modulated signals based on Cumulant is proposed. An index, energy ratio coefficient is defined to assess signals modulated degree. Theoretical data and Simulation data are analyzed, and it is found that the energy ratio coefficient increases with the increasing modulated degree.

Abstract: The moving beam of large forging hydraulic press is taken as a research object. A mathematic model of moving beam’s six freedom degrees attitude is established. According to the mechanical feature and special working conditions of large forging hydraulic press, a non-contacted method for moving beam attitude measuring which based on machine vision is proposed. The basic principle and composition of the system are introduced. The system is applied in 300MN large forging hydraulic press, and large amounts of monitoring data are collected which confirm that the measuring method is effective. The research result is helpful for the safety operation and maintenance of large forging hydraulic press.

Abstract: The quantity of official cars increased with the speed exceeding 20% every year which need much more energy be consumed to meet the official car needs. To investigate the energy saving potential of official cars in China, This paper introduced the strategy method with systemic viewpoint to reduce official cars energy consumption through analyzing the reason of high energy consuming of official cars. The resulted showed that only reduce the quantities and maintenance cost, and decline the displacement and using frequency can realize fuel efficiency of official cars.

Abstract: Based on the vehicle crash finite element theory and the virtual proving ground (VPG), vehicle frontal crash is simulated. Under the VPG environment, the unit element meshes are determined for the entire vehicle CAD model, whereas the element types and material parameters, together with welding nodes, contacts and constraints are defined. According to the ECER94 safety regulations, a rigid wall model, along with initial crash conditions is established. By calling the LS-DYNA, the simulation model is calculated and the stress distribution, vehicle body aberration nephogram, energy and acceleration curves are attained. Afterwards, the vehicle crash safety performance is obtained through simulation. Therefore, this approach sets a reference for vehicle mass assessment.

Abstract: The maximum efficiency of permanent magnet synchronous motor (PMSM) is studied and analyzed on the problem of the efficiency of motor driving system in the paper. Maximum efficiency and minimal loss have the same meaning, the mathematical model of the inverter and the PMSM are set up, thus the relationship between system loss and the stator flux is derived. Therefore, the value of the maximum efficiency of PMSM driving system can be achieved according to the expression of the stator flux. With the use of MATLAB/SIMULINK, the advantages of the loss model method and the search optimization method can be combined effectively to establish the driving system simulation model. While keeping the output-power constant by detecting the inverter-side DC voltage and current, the maximum efficiency and minimum loss in the overall range can be achieved rapidly.

Abstract: This paper presents simulation method for a new camera robot system. A special mechanism of 7 DOF which allow the robot to work flexibly in variable workspace is designed. The performance of the proposed mechanism is verified reasonable by simulation in Matlab. Additional, control system for the camera robot is presented in this paper.