Time filter

Source Type

Guo Z.,Beihang University | Lv C.,Beihang University | Lv C.,State Key Laboratory of Virtual Reality Technology and Systems
Vibroengineering Procedia

In the past decades, virtual maintenance has been a vital tool to assist product maintainability design. However, these is few report about the vibration effects on maintenance which has been proved significantly to enhance worker fatigue. In this study, we develop a platform, Semi-physical Simulation Platform (SSP), to analyze vibration effects on maintenance where an advanced Rapid Upper Limb Assessment (A-RULA) is also proposed to realize both static and dynamic assessment of worker postures and fatigue. Furthermore, a series experiments with a specified maintenance task are taken into SSP to investigate the vibration effects on maintenance. The results demonstrate reasonable conclusions about the effects of various frequency vibration and fatigue on maintenance time, maintenance errors, and A-RULA obtained from SSP. © JVE INTERNATIONAL LTD. Source

Lu C.,Beihang University | Lu C.,Science and Technology Laboratory on Reliability and Environmental Engineering | Lu C.,State Key Laboratory of Virtual Reality Technology and Systems | Cheng Y.,Beihang University | And 3 more authors.
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering

Control components of the aircraft environmental control system (AECS), which is fast becoming an increasingly complex system, are of significant importance from the viewpoint of safety. However, few studies have focused on fault diagnosis of the AECS. This study proposes a method based on adaptive threshold and parameter extraction (ATPE) to realize fault detection and isolation for control components in the AECS. To overcome the drawback of a fixed threshold for fault detection, a practical approach is employed by combining a radial basis function (RBF)-based observer with an RBF-based adaptive threshold producer. The RBF neural network observer is used to generate a residual error signal. By comparing the residual error signal with the adaptive threshold, fault occurrence can be detected. To improve the fault isolation accuracy, an RBF fault tracker is used; the parameters of this tracker are extracted for fault isolation along with the residual error, unlike in the case of conventional fault diagnosis methods that are based on a single residual error signal. Finally, an RBF-based fault isolator is adopted to realize fault isolation and classification. Two commonly occurring faults in the control components of the AECS are simulated to verify the performance and effectiveness of the proposed method. The experimental results demonstrate that the proposed method based on ATPE is effective for fault detection and isolation for the control components in the AECS. © IMechE 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav. Source

Bai X.,Beihang University | Bai X.,State Key Laboratory of Virtual Reality Technology and Systems
Journal of Microscopy

To enhance unclear microscopy mineral images, an algorithm based on toggle operator using opening and closing is proposed in this paper. Firstly, the specified toggle operator using opening and closing through designing the selection rules is analysed. Secondly, after importing the multiscale theory into the specified toggle operator, useful mineral image features, especially the mineral details, are extracted using the multiscale theory-based toggle operator. Finally, the mineral image is enhanced through the strategy of enlarging the contrast between the extracted bright and dark image features. Experimental results on different types of mineral images verified that the proposed algorithm could effectively enhance mineral images and performed better than some other algorithms. The enhanced mineral image is clear and contains rich mineral details, whereas the grey scale distribution of the original mineral image is appropriately maintained. This would be useful for the further mineral analysis. Therefore, the proposed algorithm could be widely used for image-based mineral applications. © 2013 Royal Microscopical Society. Source

Xu X.,State Key Laboratory of Virtual Reality Technology and Systems | Xu X.,Beihang University | Yang F.,Beihang University | Zhang P.,Beihang University
Proceedings of the 2011 Chinese Control and Decision Conference, CCDC 2011

This article designs a cooperative mission management system (CMMS) architecture for a multi-agent team using the integrated method, which units the control center subsystem for the team mission assignment and the onboard management subsystem for the sole autonomous management in an effective way. The proposed distributed architecture under the distributed center-control distributes the control center subsystem on the ground station and the leading agent, whereas the onboard management subsystem on team members, assigning the system workload among the ground station and the agents logically. In this way, this architecture ensures the team's flexibility and the system's reliability. The designed onboard management subsystem, based on the concept of operating system, offers high level of autonomy and separates the specific dynamic characteristics of agents from the users by the way of hierarchism control so that the system can be used generally for a heterogeneous group of agents. The system's modularization makes the system easier for function expansion and upgrading in the near future. The system is simulated on the test bed consisting of the Labview and the C language. And the results show that the designed system can satisfy the requirements of a multi-agent team cooperative mission management fully. © 2011 IEEE. Source

Lu C.,State Key Laboratory of Virtual Reality Technology and Systems | Lu C.,Beihang University | Ma N.,Beihang University | Ma N.,First Aeronautical Institute of Air Force | And 2 more authors.
Eurasip Journal on Advances in Signal Processing

In this article, a parallel radial basis function network in conjunction with chaos theory (CPRBF network) is presented, and applied to practical fault detection for hydraulic pump, which is a critical component in aircraft. The CPRBF network consists of a number of radial basis function (RBF) subnets connected in parallel. The number of input nodes for each RBF subnet is determined by different embedding dimension based on chaotic phase-space reconstruction. The output of CPRBF is a weighted sum of all RBF subnets. It was first trained using the dataset from normal state without fault, and then a residual error generator was designed to detect failures based on the trained CPRBF network. Then, failure detection can be achieved by the analysis of the residual error. Finally, two case studies are introduced to compare the proposed CPRBF network with traditional RBF networks, in terms of prediction and detection accuracy. © 2011 Lu et al; licensee Springer. Source

Discover hidden collaborations