Multi-objective dimensional optimization of parallel kinematic manipulators(PKMs) remains a challenging and worthwhile research endeavor. This paper presents a straightforward and systematic methodology for implementi...
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Multi-objective dimensional optimization of parallel kinematic manipulators(PKMs) remains a challenging and worthwhile research endeavor. This paper presents a straightforward and systematic methodology for implementing the structure optimization analysis of a 3-prismatic-universal-universal(PUU) PKM when simultaneously considering motion transmission, velocity transmission and acceleration transmission. Firstly, inspired by a planar four-bar linkage mechanism, the motion transmission index of the spatial parallel manipulator is based on transmission angle which is defined as the pressure angle amongst limbs. Then, the velocity transmission index and acceleration transmission index are derived through the corresponding kinematics model. The multi-objective dimensional optimization under specific constraints is carried out by the improved non-dominated sorting genetic algorithm(NSGA Ⅱ), resulting in a set of Pareto optimal solutions. The final chosen solution shows that the manipulator with the optimized structure parameters can provide excellent motion, velocity and acceleration transmission properties.
A more rational characterization method for the strength of notched materials of heterogeneous brittle metals is desired than the present method without considering the real material behavior. This study aims to analy...
A more rational characterization method for the strength of notched materials of heterogeneous brittle metals is desired than the present method without considering the real material behavior. This study aims to analyze the role of local plastic strain in the fracture process in notched brittle metals. In this study, we therefore conducted a four-point bending fracture test on gray cast iron with a semi-circular notch and performed fractography analysis of the fractured surfaces using an electron microscope and plastic strain analysis near the fractured surfaces using Electron BackScatter Diffraction. Based on the results, a model was proposed for the crack initiation and stable crack propagation mechanisms those clarified the role of the material structure and plastic strain on the crack behavior. This model divided the crack behavior into three stages. The first and second stages corresponded to the normal fracture process zone, wherein strain from the structure was the main cause of the crack propagation; however, in the third stage, the main cause was the elastic energy, which expressed the material as a continuum.
Accurate identification and position of transmission lines is critical for robots to safely and effectively perform distribution network operations. However, such tasks are often challenged by complex lighting conditi...
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ISBN:
(数字)9798350368604
ISBN:
(纸本)9798350368611
Accurate identification and position of transmission lines is critical for robots to safely and effectively perform distribution network operations. However, such tasks are often challenged by complex lighting conditions, where depth information can be easily lost. Transmission lines have limited texture features and reflective surfaces, making it difficult to match image feature points. To address these challenges, this paper proposes a visual perception system for weak texture targets under complex lighting, based on an “eye-on-hand” configuration and a depth complementation algorithm. Furthermore, a high-precision identification and localization method for transmission line grasping points is developed, utilizing the fusion of binocular visual color maps and depth maps. The proposed method has been shown to effectively solve the problem of identifying and localizing the grasping points of transmission lines under complex lighting conditions. Experiments demonstrated that the method can improve the localization accuracy to within $\pm 4\text{mm}$ , outperforming other algorithms. The method is characterized as simple and efficient, and it enhances the environmental adaptability of distribution network robots.
In recent years, flexible electronic devices have attracted much attention. Accordingly, flexible transparent conductive films are being researched actively. The commonly used indium tin oxide (ITO) transparent conduc...
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In recent years, flexible electronic devices have attracted much attention. Accordingly, flexible transparent conductive films are being researched actively. The commonly used indium tin oxide (ITO) transparent conductive film has limited flexibility. Therefore, we focused on poly(3,4-ethylenedioxythio- phene)/poly(styrenesulfonate)(PEDOT:PSS) as a substitute material for ITO and are engaged in producing flexible transparent conductive film using inkjet printers. To improve the characteristics of the transparent conductive film produced by inkjet printing, based on prior research, we found that cleaning the film substrate with ultraviolet/ozone (UV/O3) and post-deposition annealing and treatment using polar solvents are effective for thin films. In this study, we examined the method of applying the polar solvent. As a result, we were able to improve the homogeneity of the thin film surface by applying the polar solvent to each thin film lamination layer. The resulting characteristics obtained for a three-layer printed PEDOT:PSS thin film with polar solvent coating were resistivity of 1.49 × 10-3 Ω·cm and transmittance of 84.6%. However, we found that the surface condition changed depending on the processing method, affecting the rate of visible light transmittance.
Many real-world optimization problems exhibit dynamic characteristics, posing significant challenges for traditional optimization techniques. Evolutionary Dynamic Optimization Algorithms (EDOAs) are designed to addres...
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Pavement cracks are caused by various factors such as aged deterioration, load and weather conditions, and so on. As these cracks reduce the safety of road traffic, regular inspections are necessary. In recent years, ...
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The workload of drivers increases rapidly after the critical events and the period of time for workload to stabilize is worthy to investigate due to the close relationship between the workload and driving performance ...
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A current trend in industries such as semiconductors and foundry is to shift their visual inspection processes to Automatic Visual Inspection (AVI) systems, to reduce their costs, mistakes, and dependency on human exp...
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As a rehabilitation aid,lower-limb rehabilitation robots help patients recover their walking *** paper presets a review of such a rehabilitation ***,we classify commercially available common types of lower-limb rehabi...
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As a rehabilitation aid,lower-limb rehabilitation robots help patients recover their walking *** paper presets a review of such a rehabilitation ***,we classify commercially available common types of lower-limb rehabilitation ***,we briefly describe the structure and characteristics of those robots,Then,we present the control methods used in those ***,we explain future research directions.
This paper considers online convex optimization with long term constraints, where constraints can be violated in intermediate rounds, but need to be satisfied in the long run. The cumulative constraint violation is us...
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