Robotic Systems and Applications
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Influence of wheelset structural flexibility on dynamic properties of a wide-gauge six-axle heavy-haul locomotive
Get PDFWheelset structural flexibility, that is the elastic deformation of the wheelset as a structure, has an important influence on the dynamic properties of railway locomotive vehicles at medium and high frequencies. Based on the practical structural parameters, this paper proposes a multi-degree of freedom rigid-flexible coupling dynamic model of a wide-gauge freight electric locomotive with C0-C0 bogies with an axle suspension driving system. The wheelset with the interference-fit large gear is made flexible using the finite element method, and then the rigid-flexible coupling vehicle model with elastic wheelsets is established in the software SIMPACK 2020. A short-wave irregularity superposed on the American fifth-grade track irregularity is used as the track excitation to study the performance at higher frequencies. From the modal analysis of the vehicle, it is obtained that the lowest frequency at which the elastic deformation of the wheelset occurs is 24.631 Hz. The lateral vibration responses of the vehicle with elastic wheelsets are reduced mainly in the frequency range of 30-150 Hz. There are two resonances in the lateral vibration responses at the mode frequencies of the vehicle over 50 Hz, which are close to the wheelset’s first mode frequency. Taking the ГОСТ standard of wide-gauge countries as the main reference, simulations are separately taken in straight-line and curved-line cases. Results show that the wheelset structural flexibility mainly influences the vehicle lateral stability and safety
Research on road damage recognition and classification based on improved VGG-19
Get PDFIn recent years, methods of road damage detection, recognition and classification have achieved remarkable results, but there are still problems of efficient and accurate damage detection, recognition and classification. In order to solve this problem, this paper proposes a road damage VGG-19 model construction method that can be used for road damage detection. The road damage image is processed by digital image processing technology (DIP), and then combined with the improved VGG-19 network model to study the method of improving the recognition speed and accuracy of VGG-19 road damage model. Based on the performance evaluation index of neural network model, the feasibility of the improved VGG-19 method is verified. The results show that compared with the traditional VGG-19 model, the road damage VGG-19 road damage recognition model proposed in this paper shortens the training time by 79 % and the average test time by 68 %. In the performance evaluation of the neural network model, the comprehensive performance index is improved by 2.4 % compared with the traditional VGG-19 network model. The research is helpful to improve the model performance of VGG-19 road damage identification network model and its fit to road damages
Development of a method for online control of plastic deformations of a tank wall and assessment of its residual life
Get PDFA method of operational control of the residual resource of the tank is proposed. As a tool, the measurement of deformations of the tank wall, the assessment of plastic deformations are used. To determine the deformation, it is proposed to use a light guide installed on the wall, with the help of which the change in the curvature of the wall is measured. A device prototype containing a light guide and the necessary electronics has been developed, and the dependence of the device readings on the curvature of the light guide has been experimentally determined. The simulation of the tank in the computer simulation program was carried out in order to compare the integral of the relative deformation over the height of the tank with the readings of the device. An algorithm for processing measurements of device readings and estimating the residual life of the tank is proposed
Automatic vibration control method for grasping end of flexible joint robot
Get PDFBecause flexible robots have flexible components such as reducers, there are problems of accuracy deviation and end vibration in the process of external interference and trajectory tracking. This leads to the proposal of a Sliding Mode Control Approach Based on RBF Neural Network (SMC-RBF) parameter optimization. This method is mainly applied to reduce the end vibration and running position error of flexible robot. Firstly, the Newton-Euler method is used to establish the dynamic model of robot considering joint flexibility. At the same time, the experiment optimizes the Sliding Mode Control (SMC) method through RBF neural network. The experiments verify the control methods of the two-joint flexible robot and the six-joint flexible robot respectively. In the control of two-joint robot, the maximum tracking curve error of SMC is only about 0.25 rad under the interference of pulse signal; And the recovery time is only about 1 s. In the control of 6-joint robot, the maximum error of RBF-sliding mode control method on XYZ axis is 0.7 mm, 0.25 mm and 1.25 mm respectively; The error on three axes is smaller than that of traditional PD control method. The results demonstrate that the tracking error of the improved mode control is small, the chattering phenomenon of the robot system is weakened as well
Vibration characteristics and seismic performance of historical buildings with brick-wood structures
Get PDFTo explore the vibration characteristics and seismic performance of historical buildings in Tianjin, we conducted on-site vibration testing under ambient vibration on three historical buildings with brick-wood structures in Tianjin. Specifically, we delved into the vibration characteristics and seismic performance of historic buildings with brick-wood structures by establishing the vibration analysis model, performing the theoretical calculations, and conducting seismic performance analysis. The results reveal that 1) the vibration frequencies of historical buildings with brick-wood structures are low, mainly concentrated in 2.0-8.0 Hz, which conforms to the vibration range of general buildings; 2) based on vibration analysis, it is concluded that the structural integrity of these buildings is good and there are no obvious structural defects; 3) the layout and storey height of historical buildings have great impacts on the vibration characteristics and seismic performance. 4) the comprehensive seismic capacity index of three buildings ranges from 0.91 to 1.75. The results of dynamic analysis under ambient vibration are consistent with those of theoretical analysis, providing a basis for preserving and reinforcing historical buildings
Cross domain fault diagnosis method based on MLP-mixer network
Get PDFThe quality of rolling bearings determines the safety of mechanical equipment operation, and bearings with more precise structures are prone to damage due to excessive operation. Therefore, cross domain fault diagnosis of bearings has become a research hotspot. To better improve the accuracy of bearing cross domain fault diagnosis, this study proposes two models. One is a cross domain feature extraction model constructed using a mixed attention mechanism, which recognizes and extracts high-level features of bearing faults through channel attention and spatial attention mechanisms. The other is a bearing cross domain fault diagnosis model based on multi-layer perception mechanism. This model takes the feature signals collected by the attention mechanism model as input to identify and align the differences between the source and target domain features, facilitating cross domain transfer of features. The experimental results show that the mixed attention mechanism model has a maximum accuracy of 97.3 % for feature recognition of different faults, and can successfully recognize corresponding signal values. The multi-layer perception model can achieve the highest recognition accuracy of 99.5 % in bearing fault diagnosis, and it can reach a stable state when it iterates to 26, and the final stable loss value is 0.28. Therefore, the two models proposed in this study have good application value
Design of highly reflective film for smart radiation device
Get PDFSmart radiation device (SRD) based on the asymmetrical Fabry-Perot cavity automatically tune its IR emittance depending on the ambient temperature, making it an ideal choice for thermal control system of spacecrafts. The low solar absorption is desirable for SRD to prevent the spacecraft from overheating by sun light. In this paper, a multilayer highly reflective film with LHk stacking layers is designed to reduce the solar absorptance (As) of the Ag/Al2O3/VO2 structured SRD. The reflective film achieves a high reflection band in ~220 nm bandwidth from 460 nm to 680 nm, which results in a reduction of the solar absorptance by 25.56 % for SRD working at low temperature and 24.27 % at high temperature as the stacking factor k= 5. The simulation results indicate that an economic reflective film with k= 3 can achieve effective suppression of As of SRD, demonstrating the promising potential of the proposed reflective film in thermal control application of spacecrafts
Rehabilitation coatings-current challenges and opportunities for the future
Get PDFUnderground pipelines used for oil, gas and water distribution in Saudi Arabia and gulf region are estimated more than 33000 km in length with a range of diameters from 8 and 80 inch. Most of these pipelines are buried in different types of corrosive soil conditions and in most cases an external coating is employed along with cathodic protection (CP). Most of the existing pipelines are over 30 years old now and this is the stage to carry out rehabilitation projects for life extension of this aging infrastructure. The selection of the suitable coating systems for the rehabilitation projects is a very complicated process as it requires in depth understanding the coating/environments interactions in that particular environment along with application challenges. This paper discusses in detail the different types of external underground pipeline coating types and their selection criteria for rehabilitation projects along with recent trends and future recommendations
Use of gas reduction energy at a gas distribution station
Get PDFThe issue of utilization of excess energy of throttled natural gas is still relevant today. To solve it, various devices are used, based on such principles as on the Ranque-Hilsch vortex effect, temperature stratification using the Leontief tube, expander-generator sets and devices based on the Hartmann-Sprenger effect. One of the most common devices at gas distribution stations (gas gate station) is the turboexpander. The principle of its operation is based on the expansion of the gas flow with the performance of external mechanical work. Taking into account the increased interest in hydrogen fuel in connection with the course announced by the UN for decarbonization of production by 2050, the modern gas transmission system can become a secondary source of electricity for hydrogen production, thereby solving the problem of excess pressure energy utilization at gas distribution stations. The technological solution for using this energy is the installation of turboexpanders and electrolysis of water at gate stations in order to produce hydrogen
History of technical diagnostics and repair organization systems in industry
Get PDFThe article discusses history of technical diagnostics and repair organization in industry in Russia. The history of formation of the principles of repair, which were further formed into a system of preventive and planned repairs, is considered. At one of the stages of industrial development and the formation of repair organization systems, it became necessary to develop technical diagnostics of machines and equipment that can be carried out on working equipment. The main reasons and key points at various stages of the formation of technical diagnostics and repair organization are considered