Assembly Scheme Research Articles

Built On-orbit Robotically assembled Gigatruss (BORG): A mixed assembly architecture trade study.

This paper explores a mixed assembly architecture trade study for a Built On-orbit Robotically assembled Gigatruss (BORG). Robotic in-space assembly (ISA) and servicing is a crucial field to expand endeavors in space. Currently, large structures in space are commonly only deployable and must be efficiently folded and packed into a launch vehicle (LV) and then deployed perfectly for operational status to be achieved. To actualize being able to build increasingly large structures in space, this scheme becomes less feasible, being constrained by LV volume and mass requirements. ISA allows the use of multiple launches to create even larger structures. The common ISA proposals consist of either strut-by-strut or multiple deployable module construction methodologies. In this paper, a mixed assembly scheme is explored and a trade study is conducted on its possible advantages with respect to many phases of a mission: 1) manufacturing, 2) stowage and transport, 3) ISA, and 4) servicing. Finally, a weighted decision matrix was created to help compare the various advantages and disadvantages of different architectural schemes.

An assembly scheme of elastic bag components in a rigid shell

In this paper, the development and current situation of China's aerospace manufacturing field are summarized, and the assembly of a kind of elastic bag assembly is analyzed, and the assembly scheme is proposed, which solves the defects of difficult assembly and easy to cut the sealing ring in the assembly of elastic bag assembly. Then, the assembly process of the assembly scheme was introduced in detail, and the reliability analysis of the auxiliary tooling was carried out by using finite element software, and the feasibility of the assembly scheme was verified by digital calculation. Finally, the assembly scheme of the elastic bag assembly is summarized and prospected.

Development of Constructions for Friction Welding Devices Based on a Lathe with a Pneumatic Power Drive

The purpose of the study is to improve the design and expand the technological capabilities of special friction welding equipment based on a lathe. In order to eliminate the shortcomings identified during the laboratory test, the modernization of the structures of this device was carried out. Based on the conducted analytical studies, a power unit was selected and designed, which allows to provide the required forging pressure and thereby ensures the quality of the weld. Modeling was performed in the Siemens NX 12 application package and drawings were developed, the principle of operation was modeled and the assembly scheme was developed.

3D morphable systems via deterministic microfolding for vibrational sensing, robotic implants, and reconfigurable telecommunication.

DNA and proteins fold in three dimensions (3D) to enable functions that sustain life. Emulation of such folding schemes for functional materials can unleash enormous potential in advancing a wide range of technologies, especially in robotics, medicine, and telecommunication. Here, we report a microfolding strategy that enables formation of 3D morphable microelectronic systems integrated with various functional materials, including monocrystalline silicon, metallic nanomembranes, and polymers. By predesigning folding hosts and configuring folding pathways, 3D microelectronic systems in freestanding forms can transform across various complex configurations with modulated functionalities. Nearly all transitional states of 3D microelectronic systems achieved via the microfolding assembly can be easily accessed and modulated in situ, offering functional versatility and adaptability. Advanced morphable microelectronic systems including a reconfigurable microantenna for customizable telecommunication, a 3D vibration sensor for hand-tremor monitoring, and a bloomable robot for cardiac mapping demonstrate broad utility of these assembly schemes to realize advanced functionalities.

Assembly Strategy for Modular Components Using a Dual-Arm Space Robot with Flexible Appendages

Space robotic systems tend to be more flexible and equipped with some appendages, such as solar panels and communication antennas. The inevitable vibration in the flexible appendage will occur during space missions, and it in turn affects the attitude of the rigid base due to coupling dynamics. This study develops an assembly scheme for a dual-arm space robot with flexible appendages to assemble two modular components and to minimize the disturbance force caused by the manipulators to the base and flexible appendages. The assembly strategy consists of two stages, a preassembly stage which transports the two components to desired relative states, and a trajectory tracking stage to achieve the final assembly. In the first stage, based on a relative Jacobian matrix in the base frame, an optimal objective function is formulated in terms of the relative position and attitude errors between the two components. Thereby, more freedom of manipulators is released for minimizing disturbance forces. Notably, two virtual points are created to describe the relative position between the two components. In the second stage, two components are driven to follow a relative trajectory for the final assembly with an unchanged relative attitude. Finally, numerical simulations are conducted to demonstrate the efficiency of the proposed assembly strategy.

A Modified HODLR Solver Based on Higher Order Basis Functions for Solving Electromagnetic Scattering Problems

In this letter, we present a novel fast direct solver based on a modified hierarchically off-diagonal low-rank (M-HODLR) matrix format with higher order basis functions for analyzing electromagnetic scattering by electrically large objects. The M-HODLR matrix compresses the far-group submatrices by an extended admissibility condition, which enhances the efficiency and accuracy of the original HODLR. To further alleviate the burden of the fast direct solution of the conventional surface integral equation (SIE), the higher order hierarchical vector basis (HOHVB) functions defined over a curved surface are employed. To account for HOHVB, an efficient assembly scheme based on patch coupling is developed to accelerate the adaptive across approximation implementation in M-HODLR. The proposed method can significantly reduce the computational time and memory cost of a conventional SIE solver. Several numerical examples are presented to validate the accuracy and efficiency of the proposed method in solving electrically large objects. Owing to the characteristics of HOHVB, different patch sizes or basis functions with different orders can be chosen according to the local geometry of the object. Therefore, the proposed method is very appealing for large- and multiscale simulations.

Design and experiment of on-orbit assembly ground simulation robot

This paper proposes a space telescope assembly scheme and a ROS-based on-orbit assembly robot simulation system. First, the system fuses the hand-eye camera and the global camera ArUco marked image information to complete the identification and position and pose estimation of the structural parts to be assembled. Then, the pose information is transmitted to the ROS motion control node through Modbus-TCP communication, and the dual-arm robot system is controlled to complete motion planning and obstacle avoidance, arriving at the designated position for precise pick and place. After many simulation experiments of the designed space telescope model assembly scheme, it has been proved that the target object pose estimation algorithm is accurate, and the dual-arm collaborative robot has high position accuracy, which can realize the ground simulation autonomous assembly of large-scale space facilities. The system has certain practical application value with high integration, strong expansibility and good portability.

Analysis of a Triple-Stator Axial-Flux Spoke-Type Permanent Magnet Vernier Machine

In this article, an axial-flux permanent-magnet (PM) Vernier machine with the triple-stator, spoke-type PM rotor, and toroidal winding wound on the innerstator is proposed. Benefited from the flux focusing spoke-type PM rotor and short end length toroidal winding, the proposed machine has a high torque density and the improved power factor. Based on the air-gap permeance function, the analytical expression of the proposed machine is derived to qualitatively analyze the machine's performance. The quasi-three-dimensional (3-D) finite element analysis (FEA) is adopted to optimize the design parameters, such as innerstator diameter, PM thickness, and slot opening width. The quasi-3-D FEA results match well with the 3-D FEA. The 3-D FEA results show the torque densities of the proposed machine reach 49.4 Nm/L and 11.4 Nm/kg, respectively, under the 232 A/cm average electrical loading. The performances, such as overload capacity, PM demagnetization, and PM and core losses, are also analyzed by 3-D FEA. The comparison with the other axial-flux PM Vernier machine is conducted, and the results reveal that the proposed machine has the great advantages of the torque density and power factor. Since the prototype is not built, in this article, the assembly scheme and thermal behavior of the proposed machine are discussed.

Application of microsensors and support vector machines in the assessment of lower limb posture correction in adolescents

SummaryAutomatic monitoring of physical activity provides reliable data support for the maintenance of people's physical health and provides more scientific data for studying the relationship between physical activity and disease. In this article, a research on the evaluation of adolescent lower limb posture correction based on collaborative filtering and microsensors is carried out. Aiming at the problem that the human body posture monitoring system needs multiple nodes, this article simplifies the existing human body posture monitoring model and establishes a human body model with four degrees of freedom of the lower limbs. On this basis, the micro‐sensor assembly scheme and monitoring node layout scheme for obtaining model description parameters are determined. Methods such as collaborative filtering and support vector machines are used in the process of sensor data processing and correction effect evaluation. Finally, this article uses the constructed human body posture monitoring system to carry out the recognition test of the specific posture of the human body. The experimental results show that the evaluation scheme can effectively monitor and evaluate the effect of lower limb posture correction in adolescents.

Integrated, Transparent Silicon Carbide Electronics and Sensors for Radio Frequency Biomedical Therapy.

The integration of micro- and nanoelectronics into or onto biomedical devices can facilitate advanced diagnostics and treatments of digestive disorders, cardiovascular diseases, and cancers. Recent developments in gastrointestinal endoscopy and balloon catheter technologies introduce promising paths for minimally invasive surgeries to treat these diseases. However, current therapeutic endoscopy systems fail to meet requirements in multifunctionality, biocompatibility, and safety, particularly when integrated with bioelectronic devices. Here, we report materials, device designs, and assembly schemes for transparent and stable cubic silicon carbide (3C-SiC)-based bioelectronic systems that facilitate tissue ablation, with the capability for integration onto the tips of endoscopes. The excellent optical transparency of SiC-on-glass (SoG) allows for direct observation of areas of interest, with superior electronic functionalities that enable multiple biological sensing and stimulation capabilities to assist in electrical-based ablation procedures. Experimental studies on phantom, vegetable, and animal tissues demonstrated relatively short treatment times and low electric field required for effective lesion removal using our SoG bioelectronic system. In vivo experiments on an animal model were conducted to explore the versatility of SoG electrodes for peripheral nerve stimulation, showing an exciting possibility for the therapy of neural disorders through electrical excitation. The multifunctional features of SoG integrated devices indicate their high potential for minimally invasive, cost-effective, and outcome-enhanced surgical tools, across a wide range of biomedical applications.

Variation Analysis Considering the Partial Parallel Connection in Aero-Engine Rotor Assembly

The rotation precision of rotors determines the efficiency and quality of the overall aero-engine, as well as its long-term and reliable operation ability. As the terminal link of aero-engine manufacturing, the assembly is the last guarantee of precision control. Rotor assembly relates to the accurate expression of the connection form and design optimization of the assembly scheme. The existing variation model cannot adequately handle the partial parallel chain problem, ignoring the bayonet circular connector between the rotor parts, and it is still deficient in multistage gyration error control. In this paper, the partial parallel connection and multistage revolving characteristics of rotors were discussed, and a novel modeling and optimizing method for a partial parallel dimension chain was proposed. On the one hand, the variation expression of the connection features for the revolving components considering the partial parallel structure was researched. Contact point-based torsors were represented, and a system for locating points was regarded as an assembly to describe the partial parallel chain. On the other hand, the variation propagation modeling and control for the stacking of the multistage revolving components was researched. A revolution joint was introduced in the unified Jacobian–Torsor model, and a novel assembly technique for concentricity control was proposed. Therefore, a unified variation analysis and control method for rotor assembly has been developed. Experimental results show that through this method, the final concentricity variation is 0.0539 mm, far less than the 0.1595 mm of the traditional model, and is closer to the true value range of 0.030–0.040 mm. Moreover, the optimum installed angles can be calculated as 3.153 rad, 6.025 rad, and 2.590 rad, to obtain the highest concentricity of 0.040 mm, which has strong practical guiding significance.

Study on seismic performance of transverse frame of prefabricated elevated subway station

This paper presents an assembly scheme of double bridge column-elevated subway stations. The scheme can help to realize the assembly construction of urban elevated subway stations. A 1/6-scaled precast assembly transverse frame of elevated subway station was designed and fabricated to verify the scheme. The pseudo-static loading test was performed to investigate the bearing capacity, failure mode and hysteretic behavior of the precast assembly transverse frame. Test results showed no joint connection failure occurred during the test, and the test specimen had good ductility, indicating that the assembly scheme proposed in this paper was feasible. Finally, the finite element model was established by calling PQ-Fiber subroutine developed by Tsinghua University with ABAQUS to study the seismic performance of test specimen. And numerical simulation results were in good agreement with test results.

Experimental study of the hysteretic behavior of prefabricated frame-shear wall structures with grouting sleeve connections

In this study, a cast-in-place frame-shear wall specimen (CWS) and two prefabricated frame-shear wall specimens (PCWS1 and PCWS2) connected by grouting sleeves with different assembly schemes were tested under horizontal low-cycle reciprocating loading. The hysteretic curves, skeleton curves, ductilities, stiffness degradation, equivalent viscous damping coefficients, story drifts, crack development trends, and failure modes of the specimens were analyzed. The effects of different assembly schemes on the hysteretic behavior of prefabricated frame-shear wall structures connected by grouting sleeves were also studied. By analyzing the law of variation of reinforcement strain in the components, the interactions between the components and the overall stress mechanisms of the specimens were investigated. The results showed that the energy dissipation capacities of the prefabricated specimens PCWS1 and PCWS2 were 29.8% and 23.9% higher than that of the cast-in-place specimen, respectively; the peak bearing capacities of the prefabricated specimens were reduced by 3.1% and 5.3%, respectively, and the ultimate story drifts of the first floors were increased by 76.6% and 28.1%, respectively. The redistribution of internal forces between components caused by the separations of the interfaces between the cast-in-place regions and the prefabricated regions effectively prevented the brittle failure of the connecting beams. The introduction of additional prefabricated components in the assembly scheme facilitated local failure of the components. The stress process of a prefabricated specimen was divided into four stages. The method for calculating the lateral displacement of prefabricated specimens in the elastic range was described and suggest that the limit value of the story drift based on the elastic design method be set to the maximum value that the prefabricated frame-shear wall structures achieves in stage II.

A Carrier-free Miniaturized Ka-band T/R Module Design for Easy Automatic Assembly

A Ka-band four-channel T/R module for electronic scanning array radar is proposed in this paper, which is small in size, lightweight, easy to produce, and has good channel consistency. Adopting the open cavity design on both sides, the microwave signal and the power signal are completely isolated in space with good electromagnetic compatibility characteristics. Moreover, a “carrier-free” assembly scheme is proposed in this design, which removes the thermal matching carriers at the bottom of the MMIC chips used in traditional modules, simplifying the assembly process and achieving a high automation rate. The reliability of the scheme is verified by rigorous temperature shock and random vibration tests. The overall size of the module is 50 mm*84 mm*9.2 mm, and the weight of a single channel is only 17.5 g. The transmit saturated output power is greater than 21.5 dBm, and flatness is less than 0.8 dB. The receiving increase is greater than 7.5 dB, and flatness is less than 1 dB. The noise figure is better than 5.5 dB. The design ideas proposed in this paper have good generalization in the design of low-power T/R module.

Social governance for value creation: state-led land assembly, the property mind, and speculative urbanism in Taiwan

ABSTRACT Focusing on Taiwan's state-led, compulsory land assembly scheme (called Zonal Expropriation), we examine how the increasingly entrepreneurial state has deployed it to create land value while socially governing challenges to speculative urbanism. We argue that any development schemes that claim a priori creation of value must in fact socially construct that value in practice. Building on a case study called Central North, we show that zonal expropriation works to actively cultivate a calculating property mind(set) among affected landowners to institutionally entice participation in land taking. The article generates three important conclusions: (1) value creation is predicated on the state's taking and planning powers but not on market mechanisms alone, (2) state-led land assembly schemes, such as Central North, lock the city's urban economy in the real estate market's logic and trajectory, (3) land value creation and social governance of land conflicts have become more co-constitutive and should be relationally examined.

Anti-mutation load and error stability of a large aperture lens based on parallel collimation locking.

Based on the lens of spatial filter parallel auxiliary assembly and collimation method, aiming at the unloading and locking problem of the filter lens after collimating, a lens parallel adjustable axial locking structure was proposed. A special elastic chuck structure was designed to realize clamping axial friction locking; each branch realized interference fit, and the adjustable structure of "line-line-line" contact realized equivalent fixation through spring pre-tightening. Compared with radial locking, the abrupt error of the axial locking lens in the unloading process of a collimating auxiliary machine was small, and the posture state maintenance and structural response stability were strong. The established homogeneous transformation matrix (HTM) and lens global error showed that the pose torsion roll error of the radial locking structure was significantly suppressed. The relative stability experiment showed that the angular drift error of the lens axial locking structure was ± 0.2 µrad. The design effectively improved the unloading anti-mutation characteristics and stability of the filter lens, which provided an experimental basis for the application of intelligent collimation assisted assembly and adjustment scheme in the upgrading of a high-power laser device.

Research on the Preliminary Prediction of Nuclear Core Design Based on Machine Learning

The reactor core design involves the search for and detailed calculation of a large number of schemes. Four different machine learning algorithms were used in this technical note: the C4.5 algorithm (an algorithm of decision trees), Support Vector Machine, Random Forest, and Multi-layer Perceptron, respectively. Uranium enrichment, the number of fuel rods containing burnable poison, and the concentration of burnable poison were taken as independent variables in the calculation. The k-eff unevenness coefficient, the radial power nonuniformity coefficient, the radial flux nonuniformity coefficient, and the core life were taken as the number of core parameters fulfilled (CPF). Machine learning models were constructed through learning the training data set, which consisted of a large number of assembly and core schemes whose nuclear design parameters were already known. Using the models, the CPF values for the unknown core data set (the test data set) were quickly predicted. The results show that the cross-validation accuracy of each algorithm was above 94% and that the C4.5 algorithm had the highest accuracy for the overall prediction of the CPF values. For the CPF value prediction of the test data set, the time for the training data set was within 10s, while the Random Forest algorithm has the highest prediction accuracy for CPF = 4 or CPF ≠ 4.

Analysis and Design of a Large Diameter Shaft Assembly Scheme

Analysis and Design of a Large Diameter Shaft Assembly Scheme

Nanocomposite tectons as unifying systems for nanoparticle assembly.

Nanocomposite tectons (NCTs) are nanocomposite building blocks consisting of nanoparticle cores functionalized with a polymer brush, where each polymer chain terminates in a supramolecular recognition group capable of driving particle assembly. Like other ligand-driven nanoparticle assembly schemes (for example those using DNA-hybridization or solvent evaporation), NCTs are able to make colloidal crystal structures with precise particle organization in three dimensions. However, despite the similarity of NCT assembly to other methods of engineering ordered particle arrays, the crystallographic symmetries of assembled NCTs are significantly different. In this study, we provide a detailed characterization of the dynamics of hybridizations through universal (independent of microscopic details) parameters. We perform rigorous free energy calculations and identify the persistence length of the ligand as the critical parameter accounting for the differences in the phase diagrams of NCTs and other assembly methods driven by hydrogen bond hybridizations. We also report new experiments to provide direct verification for the predictions. We conclude by discussing the role of non-equilibrium effects and illustrating how NCTs provide a unification of the two most successful strategies for nanoparticle assembly: solvent evaporation and DNA programmable assembly.

Many-Objective Optimization and Decision-Making Method for Selective Assembly of Complex Mechanical Products Based on Improved NSGA-III and VIKOR

In Industry 4.0, data are sensed and merged to drive intelligent systems. This research focuses on the optimization of selective assembly of complex mechanical products (CMPs) under intelligent system environment conditions. For the batch assembly of CMPs, it is difficult to obtain the best combinations of components from combinations for simultaneous optimization of success rate and multiple assembly quality. Hence, the Taguchi quality loss function was used to quantitatively evaluate each assembly quality and the assembly success rate is combined to establish a many-objective optimization model. The crossover and mutation operators were improved to enhance the ability of NSGA-III to obtain high-quality solution set and jump out of a local optimal solution, and the Pareto optimal solution set was obtained accordingly. Finally, considering the production mode of Human–Machine Intelligent System interaction, the optimal compromise solution is obtained by using fuzzy theory, entropy theory and the VIKOR method. The results show that this work has obvious advantages in improving the quality of batch selective assembly of CMPs and assembly success rate and gives a sorting selection strategy for non-dominated selective assembly schemes while taking into account the group benefit and individual regret.