Complex Electromechanical Products Research Articles

A Novel Polynomial-Time Algorithm for Automatic Layout of Branching Cables in a Fixed Topology

Designing the layout for complex electromechanical products involves the challenging task of automatically laying out cables. This challenge is particularly pronounced in the case of branch cables, which are more intricate due to their multiple connection terminals and branches. This paper presents a polynomial-time wiring algorithm based on dynamic programming to determine branching point locations in the layout design of cables, given the electrical definition of the wire harness. The method considers various engineering constraints, including obstacle avoidance, wall adherence, minimum bend radius, and gray areas. To validate our method, we implemented a branch cable auto-layout system through secondary development based on the UG platform. The experimental results indicate the effectiveness of our approach, demonstrating promising performance in terms of time and high-quality layouts. This showcases its potential for practical application in cable layout design for complex electromechanical systems.

Research on kitting evaluation method of complex electromechanical products

Precise and efficient product kitting evaluations are vital for boosting assembly performance and customer contentment for varied, small-batch, and intricate electromechanical products. However, current enterprise resource planning systems (ERP) provide inadequate support for analyzing the kitting of products. How to evaluate the degree to which customers' demands for a complete set of multiple products can be met when adjusting the importance level of customer demands without changing the customer demand date in the production system and affecting the scheduled customer orders has become one of the urgent problems that enterprises need to solve. In response to the above issues, this article presents a method for evaluating product kitting, which takes the maximum quantity of complete sets of products as the optimization objective, considers multiple constraints such as material inventory data and in process business data, and designs a multi-level BOM decomposition algorithm. Finally, a case study of a company producing core components for standard high-speed trains demonstrates the practicality and efficacy of the proposed method.

A reliability evaluation method of complex electromechanical products based on the multi-stress coupling acceleration model

This paper proposes a reliability evaluation method based on a multi-stress coupling acceleration model. It can be used for testing complex electromechanical products that have high reliability, long lifetimes and small samples. Considering complex and diverse failure modes, as well as the coupled competitive characteristics of electromechanical products, a coupling competition physics of failure (PoF) model based on a Copula function was constructed, together with a proposed solution. Regarding the complex stress types and coupling relations that occur during the service of electromechanical products, a multi-stress coupling quantitative method based on a coupling matrix is proposed to analyse multi-stress coupling failure mechanisms. Moreover, the developed model is a multi-stress coupling acceleration model, which is solved using a maximum-likelihood function and covariance matrix. Finally, the reliability of a servo system was evaluated and the results compared with those of a traditional method without consideration of coupling competition of failure modes and multi-stress coupling. The proposed method is superior in terms of evaluation accuracy and application range.

Screening Critical Design Parameters for Electromechanical Products Performance Matching Based on Energy and Causal Model

The design parameters are the most momentous factors in carrying out performance matching. For complex electromechanical products with a large number of design parameters, determining a set of critical design parameters which have a great influence on the performance is the premise of performance matching. In this paper, from a systematic perspective, a screening method of critical design parameters based on energy and a causal model is proposed. Since energy is the driving force of the product operation to achieve performance, the design parameters affect the performance through energy flow in the product. Therefore, the causal model among design parameters, characteristic energy, and performance is established, where its path coefficients are determined based on the quantitative calculation of the energy flow simulation model. Then, the performance pertinence is defined and calculated to describe the comprehensive influence of the design parameters on performance and to screen the critical parameters. Finally, the performance matching process is presented to support the performance matching. With a refrigerator as an example, 5 parameters were screened from 11 variable design parameters, and day power consumption decreased by 6.85%, which verifies the effectiveness of the method.

Multi-Objective Surrogate Modeling Through Transfer Learning for Telescopic Boom Forklift

Simulation and optimization methods have been widely used in forklift design due to their cost-effectiveness. However, this type of method involves challenges such as the accuracy of the simulation model and the simulation solution time. These challenges reduce the stability and precision of the surrogate model and hence generate further optimization errors. In this paper, a multi-objective surrogate modeling (MSM) method for telescopic boom forklifts based on closed-loop transfer learning is proposed in order to solve these challenges. The MSM consists of the following two steps: to pre-train an initial deep neural network model (deep model) with a large amount of existing simulation data from the same type of forklift and to transfer the model with a small amount of measurement data collected on the current forklift. A general framework for deep neural network (DNN) training is introduced to improve the approximation ability of the initial model. Moreover, a novel uncertainty-analysis-based sampling method is suggested for measurement data development, and combined with transfer learning to form a closed-loop mode to improve the stability of the final model. The superiority of MSM is demonstrated through comparative studies with the fine-tuning method on a telescopic boom forklift with two objectives. The experimental results show that the Correlation coefficient (R) of the deep model can reach 0.9971 by using only 80 sets of training data. In addition, it can also achieve an improvement of at least a 13.25% reduction in Root Mean Squared Error (RMSE) and a 9.19% reduction on average in Maximum Absolute Error (MAE), as well as stronger robustness compared to the benchmarks. Furthermore, it will provide a valuable reference for the simulation optimization of complex electromechanical products.

Research on Preload and Stress Distribution of Small-Size Precision Threaded Connection Considering Geometric Deviation

The small-size threaded connection is one of the main connection methods for complex and precision electromechanical products such as aerospace equipment. The geometric deviation is unavoidable in the thread manufacturing process, which will lead to the problem of excessive dispersion of the connection preload and uneven stress distribution, resulting in a low product qualification rate and a short stability period. In this paper, the influence of thread geometric deviation on preload and stress distribution is studied by taking the small-size M2 thread commonly used in high-end aerospace precision products. Firstly, the thread engagement model with geometric parameters is established, and the influence of different types of geometric deviations on the preload is analyzed. Secondly, the mechanism of non-uniform stress distribution on the connector in the process of thread engagement is analyzed. Finally, the accuracy of the simulation model and the analysis results are verified by the small-size thread-tightening experiment. The results show that the pitch diameter deviation, profile angle deviation, and pitch deviation of precision thread affect the preload and stress distribution, among which the profile angle deviation has a significant influence on the preload and stress distribution.

Research on Assembly Scheduling of Complex Electromechanical Products Based on Improved Particle Swarm Optimization

The assembly shop production scheduling of complex electromechanical products is a typical discrete variable NP-hard problem. In order to solve the assembly job scheduling problem of a large transformer assembly shop, an improved particle swarm algorithm is used to solve the optimal assembly task scheduling result. In order to minimize the maximum completion time, the traditional particle swarm optimization (PSO) algorithm was improved according to the characteristics of large transformer assembly process. First, the two-stage coding method of process and assembly team is adopted. Then, in order to improve the quality of the initial solution, the initialization method that minimizes the completion time is selected, and the adaptive inertia weight optimization speed update formula is adopted. Finally, the simulation study is carried out with relevant example data. Compared with the traditional PSO, the maximum completion time and convergence speed are significantly improved, which verifies the effectiveness of the improved PSO, and obtains the production scheduling Gantt chart of the workshop.

Weakness Ranking Method for Subsystems of Heavy-Duty Machine Tools Based on FMECA Information

Heavy-duty machine tools are composed of many subsystems with different functions, and their reliability is governed by the reliabilities of these subsystems. It is important to rank the weaknesses of subsystems and identify the weakest subsystem to optimize products and improve their reliabilities. However, traditional ranking methods based on failure mode effect and critical analysis (FMECA) does not consider the complex maintenance of products. Herein, a weakness ranking method for the subsystems of heavy-duty machine tools is proposed based on generalized FMECA information. In this method, eight reliability indexes, including maintainability and maintenance cost, are considered in the generalized FMECA information. Subsequently, the cognition best worst method is used to calculate the weight of each screened index, and the weaknesses of the subsystems are ranked using a technique for order preference by similarity to an ideal solution. Finally, based on the failure data collected from certain domestic heavy-duty horizontal lathes, the weakness ranking result of the subsystems is obtained to verify the effectiveness of the proposed method. An improved weakness ranking method that can comprehensively analyze and identify weak subsystems is proposed herein for designing and improving the reliability of complex electromechanical products.

Vibration load and transfer path identification of vehicle using inverse matrix method based on singular value decomposition

Based on the theory of inverse transfer matrix, a novel method for simultaneous load identification of vehicle vibration is presented in this paper. Some response, excitation, reference points (called key points) and their transfer paths, which have severe effects on the vibration of a whole vehicle, are defined. The transfer functions among the key points are measured by experiments, and thereby a transfer function matrix of vehicle vibration is established. To solve ill-conditioning problem in the transfer function matrix, the methodology of singular value decomposition is introduced into matrix inversion in the excitation load identification. To reduce the identification error, four transfer function matrices with different reference points and condition numbers are selected and discussed. The results show that the more the reference points are, the smaller the condition number of transfer function matrix is, the higher the accuracy of excitation load identification. The transfer function matrix with minimum condition number is used to identify the excitation loads at the vehicle key points. Experimental verifications suggest that the newly proposed method is effective and feasible for excitation load identification of vehicle vibration. Using the identified excitation loads, furthermore, the vibration causes of the steering wheel and seat rail are obtained, which is helpful for improving vibration performance of the sample vehicle. In applications, the excitation load identification method proposed in this paper may be applied not only to other types of vehicle, but also to other complex electromechanical products for load identification in engineering.

A review: virtual assembly of flexible cables based on physical modeling

PurposeCables are widely used, and they play a key role in complex electromechanical products such as vehicles, ships, aircraft and satellites. Cable design and assembly significantly impact the development cycle and assembly quality, which is be-coming a key element affecting the function of a product. However, there are various kinds of cables, with complex geo-metric configurations and a narrow assembly space, which can easily result in improper or missed assembly, an unreasonable layout or interference. Traditional serial design methods are inefficient and costly, and they cannot predict problems in installation and use. Based on physical modeling, computer-aided cable design and assembly can effectively solve these problems. This paper aims to address virtual assembly (VA) of flexible cables based on physical modeling.Design/methodology/approachMuch research has focused recently on virtual design and assembly-process planning for cables. This paper systematically reviews the research progress and the current state of mechanical models, virtual design, assembly-process planning, collision detection and geometric configuration and proposes areas for further research.FindingsIn the first instance, the main research groups and typical systems are investigated, followed by extensive exploration of the major research issues. The latter can be reviewed from five perspectives: the current state of mechanical models, virtual design, assembly-process planning, collision detection and geometric configuration. Finally, the barriers that prevent successful application of VA are also discussed, and the future research directions are summarized.Originality/valueThis paper presents a comprehensive survey of the topics of VA of flexible cables based on physical modeling and investigates some new ideas and recent advances in the area.

Collection and Storage of Assembly Quality Data of Complex Electromechanical Products

In the context of made in China 2025 and intelligent manufacturing, “data-based decision” is one of the important concepts for quality management promotion, and data integrity and availability is an important aspect of data collection and data management. Combined with the characteristics of complex electromechanical products with complex structure, multiple development links and high quality requirements, this paper discusses the management category of quality big data from the perspective of manufacturing process operation management and product life cycle, studies the acquisition strategy by manual and automatic methods, acquisition process, the quality data modeling and expression specifications based on unified coding specifications and business flow and data flow framework and provides references for enterprises to carry out quality big data construction.

Overview of Key Quality Characteristics Identification of Complex Electromechanical Products

Overview of Key Quality Characteristics Identification of Complex Electromechanical Products

A Mapping Network Model Integrating Service to Warrant Function Availability of Complex Electro-mechanical Products

In recent years, in order to obtain value increment of enterprises, product service system (PSS) that integrates products and services is attracting more and more attentions in life cycle. Meanwhile, in the product usage phase, the maintenance actions undertaken in-house by customers haven’t fully warranted products’ availability for increasingly complex electro-mechanical products. So, for the purpose of warranting function availability (i.e. the availability of a function for operation) and improving equipment's operation performance by integrating services, it is necessary to allow for the complex interactive relationships among functions, structures and services to implement service's integration. According to the research on PSS, to further discuss the integrating and mapping process from the standpoint of network modeling, the mapping network model integrating service is proposed. Concretely, this model includes function layer, structure layer, service layer and their mapping network relationships. In function layer, a multi-view function decomposition model with hierarchical design structure matrix (HDSM) is introduced to present function nodes and their inherent correlations, comprehensively. In structure layer, the structure nodes are mapped from normalized mapping process and their interdependence relationships are also quantified to fulfill the integration of structure network. In service layer, the concept of service activity chain (SAC) is presented to fulfill the mapping from structure nodes to service nodes with the advantage of failure tree analysis (FTA). What's more, the provider nodes are also integrated in it. Thereby, once the network is built, the functions of equipment could be warranted effectively by corresponding structures and service execution processes. In the end, a simple case of honing head subassembly of CNC honing machine 2MK2263×200 is studied to verify the feasibility of the proposed method.

Configuration Modeling and Experimental Verification with 3D Laser Scanning Technology for a Constrained Elastica Cable

For large complex electromechanical products, cable digital design has a problem of low accuracy because of its large deformable characteristics. To solve the problem, an efficacious method is proposed to do cable geometry physical modeling, simulation and test for two-end constrained spatial flexible cables. Euler angles are used as generalized parametric variables to describe cable configuration on the base of Kirchhoff elastic rod theory. Via establishment of a cylindrical coordinate system according to Saint-Venant principle using end constraint, Euler angles’ Analytical solutions of the Kirchhoff equations are gained. Based on an open source geometry kernel system and using numerical integration ideas, a cable configuration simulation platform is developed in C++ environments. Then, a cable geometry measurement bench is founded with the use of 3D laser scan technology. Finally, a cable configuration simulation and experimental example is given to verify the accuracy of the proposed model and relative algorithm, through 3D positional deviation analysis.

Assembly Process Planning Method for Complex Electromechanical Products

Currently, neither the efficiency nor the effectiveness is sufficient in the area of the assemble optimization that commonly involves the genetic algorithm. A novel method to solve the cumbersome problem in the optimization of assembly sequences was proposed. On the basis of the assembly constraint matrix, the optimized assembly sequence is obtained with the proposed evaluating factors of the process requirement. That is the evolution of the original genetic algorithm to a certain extent. The effectiveness of the proposed method was proved by the comparison with the ant colony algorithm.

Assembly Planning Method Based on Design Structure Matrix

Aiming at the existent resource constraints problems during the assembly process of complex electromechanical products, mission planning method based on design structure matrix is put forward. Utlizing the divding and uniting calculation in the design structure matrix, the assembly missions are divided into several different layers. By constantly adjusting the planning method, the shortest excutive construction period under the resource constraints is obtained, with features as simplicity, intuition, easiness for computer realizing and so on. The feasibility of the method is proved by solving the assembly mission planning problems of NC machine.