Product Line Design Research Articles

Design of Heterogeneous Cyber-Physical Systems Employing Category Theory

Heterogeneous cyber-physical control systems based on digital twins are in demand by Industry 4.0. In accordance with the contemporary systems engineering methodology, such systems are designed at the level of digital models. The paper proposes approaches to formalization and subsequent automation of solving direct and inverse problems of their design. To unify descriptions of heterogeneous components, we follow a viewpoint-based approach to architecture design recommended by the international standard ISO/IEC/IEEE 42010. Following recent trends, we employ category theory as a mathematical framework for the formal description and solution of design problems. Indeed, category theory is a branch of higher algebra specifically aimed at a unified representation of objects of different nature and relationships between them. The design space of a heterogeneous cyber-physical system is constructed as a subcategory of the multicomma category, the objects of which describe possible system architectures with a fixed structural hierarchy represented from a certain viewpoint as diagrams, and morphisms denote actions associated with the parts selection and replacement during the system design. Direct design problems consist in evaluating the properties of the system as a whole by its architecture and are solved using a universal category-theoretic construction of the colimit of the diagram. The solution of inverse problems that require finding variants of the system architecture, which are (sub-, Pareto-) optimal according to the consumer quality criteria, consists in reconstructing diagrams by their colimit edges. For such reconstruction, optimization algorithms of gradient descent type are reasonable to employ, which navigate along the system design space morphisms calculating the path by means of computer algebra. Typical techniques of assembling cyber-physical systems, such as modular composition and aspect weaving, are described in the language of category theory and illustrated. As an example, we outline the design of energy-efficient robotic production lines represented from the behavior viewpoint as discrete-event simulation models.

Optimal product line design with reference price effects

A reference price is the price expectation of consumers for a product. When considering whether to buy a product, consumers usually compare its price with the reference price, which leads to psychological gain-loss utility affecting the consumers’ willingness to pay for the product. In this paper, we incorporate a reference price into the product line design problem and investigate the strategic implications of reference price effects for both the firm and consumers. We first study the optimal quality-price bundle design problem of a monopolistic firm and investigate the impact of reference price effects on the optimal quality and price decision when the number of products in the line is given. We show that as the importance of price comparison increases, the optimal range of qualities in the product line narrows. Specifically, the lowest quality in the product line is distorted upward, while the quality gap between adjacent products narrows. In particular, when consumers attach great importance to price comparison, the reference price effects may cause the firm to abandon discrimination among consumers and instead offer just a single product. We also investigate the optimal product variety setting problem considering a fixed setup cost incurred for each product in the choice set. Our numerical studies using synthetic and real-world data demonstrate that the demand model with reference price has better goodness of fit and prediction accuracy. The impact of neglecting reference price in the product line design problem is significant, potentially leading to substantial profit loss. Finally, we extend our work through general discussions of the model and through the dynamic pricing problem incorporating temporal reference price effects.

Multi-Robot Multi-Station Cooperative Spot Welding Task Allocation Based on Stepwise Optimization: An Industrial Case Study

The complicated task allocation, scheduling and planning problem with multiple stations and multiple robots commonly seen in spot welding production line design is studied in this paper. To deal with the highly coupled model combined with several task planning sub-problems, including robot cells design, robots allocation among cells, welding allocation among cells and robots, and welding scheduling for each robot, as well as numerous internal and external constraints, the traditional multi-robot task allocation (MRTA) framework is extended to a novel and uniform multi-station multi-robot (MS-MRTA) framework, and a sophisticated hierarchical optimization algorithm is proposed. Firstly, to establish the optimization model based on MS-MRTA framework as a whole, constraints such as reachability constraint, maximum speed and acceleration constraint, collision constraint and welding operation time constraint are considered, and the optimization objective is established based on the balance of welding tasks of each robot and each cell. Then, in order to solve the highly coupled model, a hierarchical optimization algorithm is proposed to divide the problem into three layers from top to bottom: the path planning of a single robot, welding task allocation among robots, and welding task allocation among cells. The path planning of a single robot is analogous to the Travelling Salesman Problem (TSP) solved by iterating the Lin-Kernighan-Helsgaun (LKH) solver with the trapezoidal acceleration and deceleration motion. To solve the welding task allocation among robots with numerous constraints, a regional assignment method was proposed which simplify the model and eliminate the accessibility constraint and collision constraint, and combined with genetic algorithm to solve the sub-problem iteratively. The welding task allocation among cells is solved based on the principle of balanced welding of each cell. Genetic algorithm is used to obtain the nested iterative solution of three sub-problems. The cases of actual door welding tasks are studied to verify the effectiveness of the proposed optimization algorithm. Compared with the method of long-term trial and error by experienced experts and two other more advanced algorithms, the proposed optimization algorithm results in a task assignment scheme with less welding time, less waiting time and an increase of welding operation productivity, which shows the effectiveness and feasibility of the multi-robot multi-station task allocation algorithm based on stepwise optimization.

FPGA programming using Quartus CAD

In any production — industrial, radio equipment, construction, or agricultural one, the design of various kinds of objects is carried out. Computer-aided design systems ensure the performance of functionally completed design tasks with the receipt of appropriate design solutions and design documents. Programs of this class solve the tasks of automating all stages of system design of varying degrees of complexity: from the production technology of a single part to the design of an entire production line. The article describes the FPGA programming algorithm. The practical significance of the work is the study of the basics of FPGA programming in the Verilog language and familiarity with the Quartus II compilation program, the main FPGA design environment by Intel FPGA, which is easily adaptable to the requirements of a specific project. The Quartus II package includes all the utilities needed to work with FPGA chips. The light version of CAD is free and is publicly available, which is very convenient for learning the basics. However, Quartus free version is often quite sufficient even for professional work. This paper will help beginners to get acquainted with the FPGA and its structure. The DE10-Lite Board with the MAX10 10M50DAF484C7G FPGA and other peripheral modules that allow doing quite complex projects is considered. Based on it, the article shows how to create an empty project for a specific FPGA and add new files to the project. A simple code is written in the Verilog language, using the basic concepts and commands of the language, to control the LEDs on the board when the corresponding buttons are pressed. It is demonstrated how to check the correctness of the written code, compile and download the firmware to the existing board through the built-in programmer. Familiarization and study of this programming language are conducted within the walls of one of the leading engineering universities of the Russian Federation, the Bauman Moscow State Technical University.

A product-process-resource based formal modelling framework for customized manufacturing in cyber-physical production systems

ABSTRACT The development of cyber-physical production systems (CPPSs) as the core of intelligent manufacturing systems facilitates frequent changes in product variants and batches, dynamic configurations of processing resources and relevant parameters during customized manufacturing. Production prediction, scheduling, and optimization in such a complex system require a consolidated theoretical foundation. Formal techniques, as one of the critical enablers toward this end, can be used to detect and analyse malfunctions in a CPPS based on product information before starting production. However, the inconsistency of information terminology during the interaction between heterogeneous production system components may lead to semantics-level ambiguities during the formal modelling process. This paper proposes a formal modelling framework for CPPS based on mathematical definitions of the unified ‘Product-Process-Resource’ concept. A factory formal model language (FFML) is defined and applied to the modelling of a real-world production scenario. The applicability and accuracy of the proposed framework are verified by transforming constructed formal models to coloured Petri-nets for simulations. The verification results have a certain guiding significance to the layout design and scheduling strategy decisions of production lines.

Robust Product Line Design by Protecting the Downside While Minding the Upside

Many decisions must be made before relevant uncertainties are revealed; hence robustness approaches to decision making are often considered. There are two major approaches to robustness in the literature: (i) maximizing the value of the worst outcome and (ii) minimizing the maximum ex post regret of the decision. While the first approach seeks the best worst‐case outcome, it may result in substantial opportunity losses relative to the ex post optimal decision; this is particularly critical in new product design decisions as it leaves the leading firm exposed to a late entrant who designs its products after uncertainties are resolved. The second approach seeks to minimize these ex post opportunity losses, but it may expose the decision maker to greater downside risk, that is, lower outcome in the worst case. Most studies have examined one of these approaches in isolation; in contrast, in this study, we explore the trade‐offs between protecting upside regret and downside risk with a focus on a product line design (PLD) problem, which relies greatly on conjoint analysis data. The PLD problem may suffer from significant uncertainty in the partworth utilities which define the attribute‐level consumer preferences on a product for different population segments. Our numerical experiments, based on a real conjoint data set, show that neither robustness approaches dominates the other and hence our proposed approach uses both. We construct a Min‐Value vs. Max‐Relative‐Regret efficient frontier to narrow down the PLD choice and propose a metric to quantify the trade‐offs and finalize the selection.

Multi-Objective Optimization of Energy-Efficient Buffer Allocation Problem for Non-Homogeneous Unreliable Production Lines

The current context of rising ecological awareness and high competitiveness, reveals a strong necessity to integrate the sustainability paradigm into the design of production systems. The buffer allocation problem is of particular interest since buffers absorb disruptions in the production line. However, despite the rich literature addressing the BAP, there are no studies that use a multi-objective framework to deal with energetic considerations. In this study, the energy-efficient buffer allocation problem (EE-BAP) is studied through a multi-objective resolution approach. The multi-objective problem is solved to optimize two conflicting objectives: maximizing production throughput and minimizing its energy consumption, under a total storage capacity available. The weighted sum and epsilon-constraint methods as well as the elitist non-dominated sorting genetic algorithm (NSGA- II) are adapted and implemented to solve the EE-BAP. The obtained solutions are analyzed and compared using different performance metrics. Numerical experiments show that epsilon-constraint outperforms the NSGA- II when considering comparable computational time. The Pareto solutions obtained are trade-offs between the two objectives, enabling decision making that balances productivity maximization with energy economics in the design of production lines.

이론적 열유동 및 랜덤 진동 해석을 적용한 EPS 보냉용기의 포장설계

Although it has recently been regulated for use as an eco-friendly policy in Korea, the use of EPS (Expanded Polystyrene) cooling boxes, which are used as cold chain delivery insulation boxes for fresh agricultural and livestock products, is also increasing rapidly as e-commerce logistics such as delivery have increased rapidly due to COVID-19. Studies were conducted to optimize the EPS cooling container through internal air heat flow of CFD (Computational Fluid Dynamics) analysis and FEM (Finite Element Method) random vibration analysis using domestic PSD (Power Spectral Density) profile of the EPS cooling box to which the refrigerant is applied in this study. In the analysis of the internal air heat flow by the refrigerant in the EPS cooling box, the application of vertical protrusions inside was excellent in volume heat flow and internal air temperature distribution. In addition, as a result of random vibration analysis, the internal vertical protrusion gives the rigid effect of the cooling box, so that displacement and stress generation due to vibration during transport are smaller than that of a general cooling container without protrusion. By utilizing the resonance point (frequency) of the EPS cooling box derived by the Model analysis of ANSYS Software, it can be applied to the insulation and cushion packaging design of the EPS product line, which is widely used as insulation and cushion materials.

How social communications affect product line design in the platform economy

The booming platform economy has made it very convenient for consumers to communicate with each other through social media whenever and wherever they want. As industry and academia have repeatedly confirmed, such social communications are now significantly changing firms' business and management practices. This paper studies how social communications affect an upstream firm's product line design in the platform economy when an online platform makes strategic contract choices. We show that for both wholesale and agency contracts, social communications increase the product line length while decreasing the product price and quality. We also identify the conditions under which social communications provide a firm with fewer incentives for product line extension under a wholesale contract than under an agency contract. On the platform side, we show that an agency contract can be preferred in the presence of social communications over a wholesale contract if and only if the commission rate is sufficiently high or both the commission rate and the product line extension fee are moderate.

A Model of Product Line Marketing

Firms offer a variety of products to meet different customer needs. In many horizontally differentiated markets, prices are stable, and firms make infrequent adjustments to their product lines. Although prior research focused on product line design, we investigate how firms should allocate their marketing effort when their product lines are fixed. We propose a simple model to analyze product line marketing. Our model exhibits a flagship product effect in which the firm’s optimal marketing effort is concentrated, provided that the ratio between consumer tastes dispersion and the convexity of the cost of marketing effort is below a threshold. The flagship product is selected according to a marketing effort allocation index that measures the trade-off between a product’s markup and its potential market share. This result is robust with or without competition and whether prices are exogenous or endogenous. Firms often experience shocks to their marketing cost because of technological improvement or externalities. If a monopolist’s cost of marketing effort declines, she should place more emphasis on a low-utility, high-markup product. Conversely, if the cost increases, the monopolist may find it beneficial to focus her marketing effort on a high-utility, low-markup product. When multiproduct firms compete against each other, we show that if the opponent’s cost of marketing effort decreases, there can be a spillover effect, in which the firm benefits from the opponent’s cost reduction, thereby leading to a win-win situation. This paper was accepted by Dmitri Kuksov, marketing.

Mechanical Design and Improvement of Computer Automatic Production Line

The mechanical design amelioration of automatic production line can intelligently adjust the production rhythm of the production line on demand, control the rhythm of production scheduling according to the production process requirements, and establish a modular design mode, so it has important research value. Based on this, this paper first analyses the mechanical design principle of the automatic production line, then studies the computer control system of the automatic production line, and finally gives the amelioration measures of the mechanical design of the automatic production line.

Posted price and name-your-own-price in a product line design problem

In this research, we address Name your own price (NYOP) as a mechanism to offer products with transparent, rather than opaque, quality levels. We compare posted price (PP) and NYOP in a product line design problem from a firm’s viewpoint. We first consider the firm offering two vertically differentiated products that each can be priced by NYOP or PP. The quality level of products is considered either as a decision variable or as a fixed predetermined value for the firm. A customer correspondingly decides which product to purchase and if applicable, the bid at NYOP. We characterize both the customer’s and the firm’s decisions under four possible pricing scenarios. The results show that, it is most profitable for the firm to use PP for both products. We then consider if each product is offered by a competitive firm, where quality levels might again be decision variables or fixed. Results show that both competitive firms prefer PP to NYOP when they can create quality differentiation. The firm that offers the product with a lower quality level prefers PP to NYOP for all combinations of fixed quality levels as well. The other firm, with a higher quality level, also usually prefers PP to NYOP; However, it can be better off using NYOP when fixed quality levels are large and close enough to each other. In this case, the preference of NYOP over PP increases as customers’ willingness to pay enhances.

Reconfigurable Production Line Design Method for Human Workers – Robotic Cell Collaborated Line Considering Worker’s Attitude Toward Work

In recent years, manufacturing companies have faced difficulties in securing sufficient production capabilities at factories because of many regional risks, such as natural calamities and epidemics. A production line should be designed to be reconfigured to adapt to various risks for satisfying its demands. This paper proposes a flexible and reconfigurable production line composed of a combination of line workers and multipurpose equipment called robotic cells. A robotic cell performs work (similar to a worker) using a programmable arm robot. The required tasks are allocated to workers or robots. However, it is difficult to design the line configuration and task allocation, because the number of combinations is large. Additionally, the production efficiency fluctuates depending on the correlations between the worker’s attitude, skill level, and allocated tasks. This paper describes a production-line design method using a genetic algorithm. The proposed method maximizes the availability ratio and minimizes the cost of the production line by considering the worker’s attitude toward the work.

Optimization of product line considering compatibility and reliability via discrete imperialist competitive algorithm

In the era of mass customization, designing optimal products is one of the most critical decision-making for a company to stay competitive. More and more customers like customized products, which will bring challenges to the product line design and the production. If a company adopts customers’ favorite levels, this may lead to lower product reliability, or incompatibility among the components that make up the product. Moreover, it is worth outsourcing certain attribute levels to reduce production cost, but customers may dislike these levels because of their delivery delay. If managers consider the compatibility issue, the quality issue, outsource determination, and the delivery due date in the product design and production stages, they will avoid unreasonable product configuration and many unnecessary expenses, thereby bringing benefits to the company. To solve this complicated problem, we establish a nonlinear program that maximizes Per-capita-contribution Margin considering Reliability Penalty. Since the integrated product line design and production problem is NP-hard, we propose an improved Discrete Imperialist Competitive Algorithm (DICA). The proposed DICA is compared with genetic algorithm (GA) and simulated annealing (SA) through extensive numerical experiment, and the results show that DICA displays 6%~17% and 5%~14% improvement over GA and SA in terms of solution quality, respectively.

Automatic Equipment Design of Intelligent Manufacturing Flexible Production Line Based on Industrial Motorized Spindle

Based on the previous research on the production line automation, this paper carries out further research and further design and development on the basis of the original production line automation equipment. In this paper, the overall design of the automatic production line is carried out, and the various systems in the automatic production line are optimized, and the backward instruments are eliminated, and then some more advanced and convenient instruments are applied. Then, the hardware and software of the automatic production line are studied respectively, and the human-computer interaction module and real-time main control circuit module are re developed, and the electric shaft is applied to the automatic production line. Finally, the fuzzy PID controller of the stepping motor is designed. The experiment shows that the fuzzy PID control scheme is better than the traditional PID control scheme. After the rationalization of the system, the quality robustness of proactive planning is improved obviously. Then, the temperature of motorized spindle was tested.

PRODUCT LINE DESIGNS with Dynamic Programming and Genetic Algorithms: A Comparison, Guide, and Caution

PRODUCT LINE DESIGNS with Dynamic Programming and Genetic Algorithms: A Comparison, Guide, and Caution

Optimization of Productivity and Worker Well-Being by Using a Multi-Objective Optimization Framework

OCCUPATIONAL APPLICATIONS Worker well-being and overall system performance are important elements in the design of production lines. However, studies of industry practice show that current design tools are unable to consider concurrently both productivity aspects (e.g., line balancing and cycle time) and worker well-being related aspects (e.g., the risk of musculoskeletal disorders). Current practice also fails to account for anthropometric diversity in the workforce and does not use the potential of multi-objective simulation-based optimization techniques. Accordingly, a framework consisting of a workflow and a digital tool was designed to assist in the proactive design of workstations to accommodate worker well-being and productivity. This framework uses state-of-the-art optimization techniques to make it easier and quicker for designers to find successful workplace design solutions. A case study to demonstrate the framework is provided.

SIMULATION MODELLING AND ANALYSIS FOR IMPROVING THE PERFORMANCE OF PRODUCTION CASE STUDY: JORDANIAN VEHICLES MANUFACTURING COMPANY

Modelling and analysing production lines are crucial for the research community and designers interested in increasing production utilisation and reducing costs. This paper aims to model and analyse a real production process of a Jordanian vehicles manufacturing company and improve production line resource utilisation using ARENA simulation software. The methodology used is simulation modelling to develop a new production line design. Performance measures are obtained from data given by the company management and direct observation of the production line. A suggested modified Arena simulation model is developed for the production line processes based on the collected data. Verification and validation analysis of the proposed model is done. Results show that the proposed model’s performance is better than the current one in terms of; overall total processing time, the overall waiting time, the overall work in process, and the overall utilisation.

Design of automatic spray monitoring and tele-operation system based on digital twin technology

To solve the problems of low degree of automation, difficulty in quality control and poor working environment during the process of spray-painting rotational parts, this paper designs an automatic spray monitoring and tele-operation system based on digital twin technology, which can realize real-time monitoring and tele-operation fault treatment during the spraying process to achieve the goal of “man-machine isolation”. First, an automatic production line for spraying operations is designed in which the spraying equipment can be remotely controlled. Then, multiple sensors are used to collect the environmental and equipment conditions. After that, multisource heterogeneous data are pretreated to construct a unified data template and interfaces. On this basis, a three-dimensional model of the environment and equipment is established. According to the fusion and mapping between sensor data and the geometric model, an augmented reality twin model of spray painting is obtained. Additionally, the relevant support database and knowledge base are established; a fault diagnosis method based on knowledge is proposed to provide support for fault treatment. Finally, an automatic spraying monitoring and tele-operation software platform is developed that can run under monitoring or tele-operation mode, and the related functions are tested and verified. The test results show that the system is more efficient than manual spraying method, and the coating surfaces is flatter, effectively reducing the probability of sagging, orange peel, missing spray and other problems. This research provides a reference for the design and construction of automatic spraying production lines.

Design of production lines and logistic flows in production

Abstract The study deals with the topic of the implementation of modern production methods with emphasis on the solution of a new production with the utilization of lean principles and respecting the limiting conditions of the production company. In the summary, an economic assessment of the designed concept using the Lean Method is presented. The outcomes of the researched problem are a performed analysis, its acceptance of the user and the acceptance of the designed concept of the new production line.