Papers by Keyword: Compensation

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Authors: Yuan Yang, Zhong Qi Wang, Yong Gang Kang, Zheng Ping Chang
Abstract: Since the bracket deformation caused by its deadweight is too large, and the riveting of aircraft panel is always over-tolerance, a new algorithm for analysis and compensation of bracket deformation is presented in this paper. The algorithm is formed by combining finite element (FE) simulation with analytic method, which is fit for different combinations of supporting plates of bracket system. The formula is constructed through cubic spline interpolation and envelope surface fitting according to the FE simulation data. Meanwhile, a corresponding compensation method is proposed. Finally, a numerical simulation example with the software of ABAQUS shows that the algorithm and its results are valid and feasible.
Authors: Zhi Yong Yu, Ming Lu, Zhen Nan Wang, Yi Gong Zhang
Abstract: With conventional droop control, parallel operation of distributed generations (DG) in microgrid would lead to unbalanced power sharing. In this paper, inherent limitation of conventional droop control is analyzed. Analysis results show that different converter output impedance and line impedance make the power sharing unbalanced. In order to weaken or eliminate impedance difference from point of common coupling (PCC) to DGs, virtual impedance is introduced. By the introduction of designed virtual impedance, a novel droop control strategy with impedance compensation is proposed in this paper. Simulation results are presented from a two converters parallel-connected microgrid, showing the effectiveness of the droop control with impedance compensation. Simulation results show that DGs with proposed approach can allocate the power equally, and work stably in grid-connected mode, island mode and progress of reconnection to grid.
Authors: K.J. Chang, Sang Guk Lee, Byoung Ho Cheong
Authors: Han Huang
Abstract: This paper summarised our recent results on the development of grinding technologies for the fabrication of aspheric components at micro/meso scales made of cemented tungsten carbide. Based on these results, a grinding protocol was proposed for the fabrication of aspheric moulds. The protocol includes the understanding of deformation and removal mechanisms of hard and brittle materials involved in grinding, the preparation of grinding wheels, the compensation of profiling errors and the optimisation of the grinding process.
Authors: Juan Liao, Chi Zhou, Feng Ruan, Yin Zhu
Abstract: The dimensional inaccuracy caused by springback is a major problem for most stamping applications. One of the most promising ways to solve this problem is to compensate it by means of appropriate tool shape modifications. In this paper, a new springback compensation method is introduced. A coefficient of curvature correction, which reflects the deviation of the experiment data and the analytical calculation data, is also proposed to redesign the tooling shape. This method was applied to a two-dimensional wavy-shaped part forming case for verification. The experiment results demonstrated that this method is efficient.
Authors: Dan Ma, Ji Da Huang
Abstract: Based on the complexity of brake, this paper simulated the exact relationship between time and motor drive current. According to the principle of robust design, analysis of experimental data obtained the current-driven expression, and on this basis we established PID control model based on system dynamics and BP neural network self-tuning, then, this paper improved compensation for the PID control model, got the computer control method which design the current value this time based on observations of the previous period, simulated the exact relationship between the time and the motor drive current. The energy error from observation of the control simulation is very small, which verifies the correctness of the control method.
Authors: Xuan Wang, Valérie Budinger, Yves Gourinat
Abstract: Piezoelectric actuators exhibit creep behavior in open-loop operation, which may lead to unaffordable errors in high precision static positioning systems. An inversion-based compensation strategy by open-loop control is presented for reducing creep effect. The approach utilizes a nonlinear viscoelastic model to portray creep phenomenon, which consists of a linear spring, a nonlinear dashpot and a series of nonlinear Voigt elements. It is shown that for the presented creep model the step responses are very similar to the piezoelectric actuators. In order to compensate creep effect, a concept of voltage relaxation in piezoelectric actuators is proposed. And the voltage relaxation model tantamount to the inverse creep model is derived using a PID closed-loop control system. Experimental results prove that, by insertion of voltage relaxation model in open-loop operation, creep effect is attenuated markedly in piezoelectric actuators.
Authors: Seung Yub Baek, Eun Sang Lee, Jong Koo Won
Abstract: This study presents the development of an ultra-precision grinding system based on a new grinding technique called the “In-Process Grinding Method (IPGM)”. IPGM which is used for grinding aspheric lens increases both the production and grinding performance, and significantly decreases total production costs. To enhance the precision grinding productivity of ultra-precision aspheric lens, we present here an ultra-precision grinding system and process for the aspheric micro-lens. The tool path was calculated and CNC program generation and tool path compensation were performed for aspheric lens. Using this ultra-precision grinding system, aspheric lens, 4mm in diameter, were successfully performed. The profile error after the first grinding without any compensation was less than 0.6μm, and surface roughness Ra was 0.01μm. In-process grinding was performed with compensation. Results of the profile accuracy P-V 0.3μm and surface roughness Ra 0.006 μm were obtained.
Authors: Wei Yan, Xian Qi Huang, Ying Sheng Zhou
Abstract: For a large percentage of control systems, the primary objective is to obtain high steady-state accuracy. Another goal is to maintain the transient performance of these systems within reasonable limits. The steady-state accuracy of many feedback systems can be increased by increasing the amplifier gain in the forward channel. We will describe the design of the integration compensation networks in order to obtain a suitable system performance.
Authors: Mei Chu, Guang Nan Guo, Yong Gang Yun, Hong Yan Shi, Jin Ping Liu
Abstract: The atomicity characteristic of traditional transaction processing makes entire transaction process to naught in case of specific event or error. To address problem of traditional transaction processing and combining with characteristics of Web service transaction processing, a Web service transaction coordination framework based on compensation was presented. The coordination algorithm and state transformation of long transaction were also provided. The framework mainly provides fault recovery of Web service to ensure atomicity of transaction and consistency of compensation. It permit participant submitting sub-transactions independently to deal with transaction fault with compensation, which can meet requirements of business transactions cross-enterprises.
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