Automobile Assembly Processes Research Articles

Optimization of the automobile engine assembly process using simulation modeling

In today’s world, internal combustion engines (ICEs) continue to play a key role in mobility and economic development. With the growing demand for vehicles and equipment with internal combustion engines, the urgency of developing new, more efficient methods for their production also increases. The purpose of this work is to increase the efficiency of the internal combustion engine assembly process by analyzing bottlenecks at the production site using a simulation model. A simulation model of internal combustion engine assembly using modern methods and tools of the AnyLogic environment is presented.

Research on the Application of Digital Manufacturing Technology in Automobile Assembly Process

Research on the Application of Digital Manufacturing Technology in Automobile Assembly Process

Sensor Optimization for Variation Diagnosis in Multistation Assembly Processes

Appropriate sensor deployment is the key to the efficient diagnosis of product variation. Yet, optimizing sensor placement in complex manufacturing systems remains challenging. We propose a variation propagation analysis (VPA)-based sensor deployment strategy for variation diagnosis in multistation assembly processes. A state-space model is employed to analyze the influences of fixture faults and workpiece dimensional deviations on assembly variation. Based on matrix transformation, the assembly variation propagation characteristics are quantified and a VPN-based causal graph is constructed to represent the causality between assembly variation and sensor measurement. To ensure the diagnosability of over-tolerance of assembly variation (OAV) and the economics of the sensor system, an optimal sensor deployment scheme is presented. It uses the enhanced shuffled frog-leaping algorithm to minimize the OAV unobservability per unit cost and the sensor cost under the constraint of detectability. Finally, the effectiveness of the proposed approach is illustrated by a case study of sensor deployment for variation diagnosis in a multistation automobile differential assembly process.

Irregularities recognition system for automotive pieces

The automotive industry is a growing sector in Mexico that requires many production processes. One of the most important is auto parts manufacturing with high-quality standards to avoid economic losses. Hence, the failure detection of pieces must be carried out in the early process, discarding those that do not reach the desired quality. This paper deals with an object recognition system to automatically find failures in circular automotive pieces. This is an open problem in the automobile assembly process to guarantee product quality. We detect imperfections (above 3.5 mm) on small pieces, such as scratches and dents on edges, by using an image processing stage, where no training is included, with a low-cost camera. The average processing time to detect failures is 2.7 seconds, which allows us to examine more pieces in a short time compared with other works and with manual inspections carried out by human experts. The proposed system reaches an accuracy of 98% and is implemented in the LabVIEW tool.

High-productivity and high-strength Fe/Al dissimilar metal joining by spot forge welding

To develop a high-productivity dissimilar joining technique, which is highly sought after in the automobile assembly process, I developed a new method based on spot forge-welding. In the lap joint of 1-mm-thick SPCC steel and A5083 aluminum plates, within the 10-mm forge diameter, a base metal fracture occurred at a reduction ratio R of 1.8. The maximum tensile-shear load reached 3.8 kN during the approximately 80-ms forge welding process. The newly formed surface at the bonded interface exhibited a mesoscopic reaction layer, in which the brittleness was minimal given the short diffusion time. Thus, this approach shows great potential to replace conventional resistance spot welding for next-generation solid-state spot welding of dissimilar joints, for high-throughput welding applications and high-strength joints.

Hybrid Nonlinear Variation Modeling of Compliant Metal Plate Assemblies Considering Welding Shrinkage and Angular Distortion

AbstractShip assembly involves thousands of large dimensional compliant metal plates. These compliant metal plates are fully welded together by seam welding in the assembly process. Different from the automobile and aerospace assembly process, the final variation of ship assembly is significantly influenced by the geometric nonlinearity and welding deformation generated during the seam welding process. This paper develops a nonlinear variation model (NVM) to consider the geometric nonlinearity, welding shrinkage, and angular distortion based on elastic mechanics. Furthermore, the nonlinear variation model is calibrated by the composite Gaussian process (CGP) to compensate for other factors that are not considered in the nonlinear variation model. The proposed model is validated by a case study on the deviation prediction of an assembly of two compliant metal plates and compared with the existing methods. The results show that the proposed model has a significant improvement in prediction accuracy of assembly deviation.

The reduction of production lead time using holonic manufacturing: experiment and analysis

PurposeIn modern industrial processes, the need of reducing lead time is imperious. This goal is pursued by “Holonic” structures, which are systems based on a network of collaboration. The purpose of this paper is to appraise the possible benefits, in terms of production duration, of such organizations compared to non-holonic arrangements. In addition, this analysis represents virtual teams, which are a significant and strategic attribute of holonic manufacturing systems.Design/methodology/approachThe experiment performed in this paper is a simulation of an automobile assembly process under both a holonic and a non-holonic structure to observe lead times and the distinctive characteristics of each organization. Other targets of this research are to monitor the advantages that either strategy may offer in terms of efficiency and to examine a possible model of how virtual teams can be used in holonic networks.FindingsThe findings are unexpected. An initial expectation might lead to the belief that, given the better coordination and communication of holonic networks, lead times would be diminished. This experiment, utilizing virtual teams of university students, indicated otherwise.Research limitations/implicationsIt should be noticed, however, that future experiments in real manufacturing assembly processes are recommended to complement the findings of this study.Originality/valueThe management of lead times is indeed a complex task that includes a diversity of variables. Holonic structures should balance several factors that might play a role in lead times and ultimately in the success of a project. An original experiment with the participation of many universities in different countries is presented in this study. The exposure of global characteristics of modern manufacturing structures constitutes the main value of this research.

Feasibility Research on Development of Product-Independent Assembly Complexity Model : A Case Study of a Refrigerator

The earlier studies about product assembly-complexity are validated in the specific product category. Therefore, product assembly-complexity model can be developed for specific product category and applied to validated product category. One of the earlier research on product assembly complexity model, which is developed by ElMaraghy, is validated only in the automobile engine assembly process. This paper applies the ACM to the process of assembling a refrigerator. For this purpose, the ACM is updated to represent the characteristics of this process. The assembly complexity calculated for a refrigerator is significantly correlated with assembly time. This result implies that the ACM can be made generic by updating or modifying it to represent the characteristic of a specific product-assembly process, and can be used for a wide range of product categories.

Optimization of Automobile Assembly Process to Reduce Assembly Time

ABSTRACTThe automobile manufacturing industry is undergoing a significant restructuring. Every automaker is investing heavily for adapting new manufacturing processes as well as assembly techniques which will reduce the overall operating costs while consistently maintaining the quality of the product. In general, assembly lines are being designed and developed with a goal to synchronize workers, machines, tools and components. It is important to have an optimized assembly operation sequence in order to facilitate the smooth functioning of an assembly line. This research paper will focus on developing an optimal vehicle assembly sequence based on the liaisons and precedence graphs concepts [3, 5]. In general, a liaison establishes the connectivity between different components in an assembly based on their connectivity with respect to each other. Using the existing liaisons, multiple feasible precedence graphs can be generated which in turn lead to the development of multiple feasible assembly sequences. Th...

Online User Identification for Power-Assist Devices about Mounting Operations in Automobile Assembly Processes

Power assist devices are broadening their range of application remarkably. According to that, these devices will expand the number of users, and will be casually used tools, which are sometimes shared in a group. In such a situation users must require a function of switching personal settings. Fortunately the power assist devices are able to observe difference of users' way of maneuvering, and it may enable to distinguish users. On these premises, this paper propose online personal identification through power assist operation behaviors. This paper examined the proposal on a setup with Skill Assist, a power assist device designed for car-production industries. The online identification method could identify the users at available short time in this experiment. By using the identification method, users can immediately obtain personalized maneuverability without performing any special authentication procedures.

Research on Optimization and Emulate Planning of Automobile Assembly Process

Assembly process planning automobile production line is the bridge between the design and large-scale production. It is extremely important. Not only it affects directly the assembly efficiency and the quality, moreover has decided the workshop building, the equipment investment, quantity of production personnel, goods in process quantity and so on. Whole optimization and the partial purification of the assembly craft will all have the huge economic efficiency, and obviously strengthen the emulative power of automobile production enterprise in the market. In order to optimize the result of craft planning, enhance the quality and efficiency of computer aided assembly process planning and reach expected output and efficiency, the optimizing of automobile ALB (Assembly Line Balancing) problem is deeply analyzed with linear programming theory. Besides, linear programming mathematical model of ALB problem is established. Based on the mathematical process modeling and the generation of assembly sequence and considered the relative factors between production line and process planning, basing chart of process for assembly line (PAL Chart) a modeling method is put forward. It includes the main parameters of the assembly process planning and displays the planning result directly.

A Smooth Switching From Power-Assist Control to Automatic Transfer Control and Its Application to a Transfer Machine

Power-assist system technology and its application to manufacturing systems have attracted special interest recently. For example, automobile assembly processes utilizing power-assist systems exist. Many power-assist systems for industrial uses possess simple power-assisting functions only. The transfer of controlled objects is generally processed by another system. This paper proposes a transfer control method for a cart with motor by means of a smooth switching from the impedance control realizing the power-assist to the servo control for automatic transfer. To obtain the smooth switching, this paper utilizes a nonstationary impedance control method whose impedance parameters are time varying. A linear quadratic integral control method based on time-varying feedback gains is also introduced. By considering the setting of the time-varying parameters, the control characteristic is smoothly varied without control input saturation. This method increases the efficiency of control processes and realizes comfortable work for operators. The effectiveness of the method is verified by experiments and simulations

Positioning Control Method Switching from Adaptive Nonstationary Servo Control to Nonstationary Impedance Control

Power-assist system technology and its applications to manufacturing systems have attracted special interest recently. For example, an automobile assembly process utilizing a power-assist system has been proposed by Yamada, et al. Many power-assist systems for industrial uses possess simple power-assisting function only. Conveyance of controlled objects is generally processed by another system. Then, the author has studied on the positioning method of a cart with motor by means of a smooth switching from the servo access control for the conveyance function to the impedance control for the power-assisting function. The nonstationary optimal control method and the nonstationary impedance control law are applied to obtain the smooth switching. However, the optimal control method requires the offline calculations for generating time-varying feedback gains. If we take parameter variations in real problems into account, this characteristic is inconvenient. To realize adaptive control for the variations, this study introduces the adaptive nonstationary control (ANSC) technique proposed by the author instead of the optimal control method.

Positioning of a Cart by Means of a Smooth Switching from Servo Access Control to Impedance Control (Realization of Force Sensorless Control)

Power-assist system technology and its applications to manufacturing systems have attracted special interest recently. For example, automobile assembly processes utilizing power-assist systems have existed. Many power-assist systems for industrial uses possess simple power-assisting function only. Conveyance of controlled objects is generally processed by another system. Then, one of the authors has studied on the positioning method of a cart with motor by means of a smooth switching from the servo access control for the conveyance function to the impedance control for the power-assisting function. The nonstationary optimal control method and the nonstationary impedance control law are applied to obtain the smooth switching. However, this method requires a force sensor for detecting the operator's force. To improve the usefulness and safety of the system, a force sensorless control method for the system is studied in this paper. Instead of the force signal, this study utilizes the acceleration signal of the cart. The method shows its effectiveness by experiments.

A Multivariate CUSUM Procedure and a Most Active Bivariate Chart

We propose a new multivariate cumulative sum (CUSUM) scheme whose components are the difference between the Page [10] univariate CUSUM statistic for detecting an increase and that for detecting a decrease. Our procedure also applies when monitoring principal components. We then suggest a new quality chart procedure where, at each new observation, the results for the two most active components are graphed. These two components are selected to have the largest value of the appropriate bivariate CUSUM statistic. This novel graphical approach, intended to augment the information in the chart based on all of the variables, is illustrated with an application to data from an automobile assembly process. We compare our new scheme with the classic T2 charts and a number of other existing multivariate CUSUM schemes, including the scheme proposed in Crosier[2]. In our simulations, among existing procedures, Crosier[2] has the best overall average run length (ARL) performance. Our new multivariate scheme has ARL performance that is usually comparable with that of Crosier’s scheme.

Optimal Design of Fixture Layout in Multistation Assembly Processes

This paper presents a methodology for the optimal design of fixture layouts in multistation assembly processes. An optimal fixture layout improves the robustness of a fixture system against environmental noises, reduces product variability, and leads to manufacturing cost reduction. Three key aspects of the multistation fixture layout design are addressed: a multistation variation propagation model, a quantitative measure of fixture design, and an effective and efficient optimization algorithm. One of the challenges raised by this multistation design is that a high-dimension design space, which usually embeds a lot of local optimums, will have to be explored. Consequently, it makes a global optimality more difficult and, if an inefficient algorithm is used, may require prohibitive computing time. In this paper, exchange algorithms, originally developed in the research of optimal experimental design, are adopted and further revised to optimize fixture layouts in a multistation process. The revised exchange algorithm provides a good tradeoff between optimality and efficiency: it remarkably reduces the computing time without sacrificing the optimal value. A four-station assembly process for a sports utility vehicle sideframe is used throughout the paper to illustrate the relevant concepts and the resulting methodology. Note to practitioners-This paper was motivated by the problem of planning a fixture locator layout in a multistation assembly process. Existing approaches generally focused on planning fixture locator layouts on a single workstation. In a multistation production process, such as an automobile body assembly process, the fixture locating holes used on one station will be reused on different stations, which could cause a station-to-station coupling in variation propagation. In other words, dimensional variation could originate from fixture elements on every station, propagate along the production line, and accumulate on the final assembly. Station-wise fixture layout design may not necessarily lead to a good solution because it overlooks the variation coupling and propagation effect. In this paper, we modeled the variation propagation across multiple stations and provided a quantitative characterization of the performance of fixture layout with the presence of environmental noises. Then, we recommended an efficient computation algorithm to solve for the optimal fixture layout. Our results showed that the multistation layout design is different from a single station one; some intuitions gained from single-station design work may not be still valid. The current work is based on a two-dimensional, rigid panel assembly model. The extension to accommodate more sophisticated two-dimensional, complaint-part assembly processes is much needed in the future research.

Warning: to err is human

In this article we describe current and future technologies for ensuring the safety of the operators maneuvering a Skill-Assist working in an automobile final assembly process. It proposes a method that allows a Skill-Assist to detect operation slip from a sequence of an operator's hand motion trajectory data represented using hidden Markov models (HMM). The method can also determine either safety- or productivity-oriented control policy throughout two-way interpretation of the belief structure. A workability improvement process that comprises a fault-warning (FW) safety-preservation (SP) space policy and teaching data renewal subprocesses allows for optimal reconstruction of the policy determinant observation space and HMMs. Some experimental results are shown to demonstrate the effectiveness of both the control policy determination and the workability improvement process.

Transfer Control Method by Means of a Switching from Impedance Control to Servo Control

Power-assist system technology and its application to manufacturing systems have attracted special interest recently. For example, automobile assembly processes utilizing power-assist systems exist. Many power-assist systems for industrial uses possess simple power-assisting function only. Transfer of controlled objects is generally processed by another system. This fundamental study proposes a transfer control method of a cart with motor by means of a switching from the impedance control realizing the power-assist to the servo control for automatic transfer. To obtain smooth switching, this study utilizes a nonstationary impedance control method whose impedance parameters are time-varying. LQI (Linear Quadratic Integral) control method based on time-varying feedback gains is also introduced. By the consideration on setting of the time-varying parameters, control characteristic is smoothly varied without control input saturation. This method increases efficiency of control processes and realizes comfortable work for operators.

Controller Design Method for Robustness Improvement of Power-Assist Control

Power-assist system technology and its applications to manufacturing systems, constructing systems, rehabilitation and welfare services have attracted special interest recently. For example, automobile assembly processes utilizing power-assist systems exist. However, the effect of such uncertainties as Coulomb friction on the power-assist systems has not been fully addressed. This study proposes a controller design method for the robustness improvement of power-assist control. Especially, we pay attention to the influence of uncertain Coulomb friction and design the servo control system consisting of two parts. The first part is an on-line impedance control simulator which works as the reference generator. The other one is a sliding mode controller to suppress the errors between the references and corresponding responses. By applying the method to the positioning problem of a cart, the effectiveness of the method is verified by experiments.

インピーダンス制御からサーボ制御に切り換わる搬送制御手法(人間機械協調1)

Power-assist system technology and its application to manufacturing systems have attracted special interest recently. For example, automobile assembly processes utilizing power-assist systems exist. Many power-assist systems for industrial uses possess simple power-assisting function only. Transfer of controlled objects is generally processed by another system. This fundamental study proposes a transfer control method of a cart with motor by means of a switching from the impedance control realizing the power-assist to the servo control for automatic transfer. To obtain smooth switching, this study utilizes a nonstationary impedance control method whose impedance parameters are time-varying. LQI (Linear Quadratic Integral) control method based on time-varying feedback gains is also introduced. By the consideration on setting of the time-varying parameters, control characteristic is smoothly varied without control input saturation. This method increases efficiency of control processes and realizes comfortable work for operators.