Autonomous Behaviour in Automated Manufacturing Systems

In this paper, a decision-theoretic approach is provided to model the autonomous behaviour among intelligent agents, e.g. machines, in automated manufacturing systems (AMS). The automated manufacturing systems make available agile manu-facturing systems with the characteristic of quick response to the customers’ needs. An autonomous agent can use the decision method to model multi-agent situations and behave rationally based on this decision-theoretic approach. The AMS is constructed in a matrix framework for rule-based controller design. The controller is comprised of inner and outer loops, where the inner loops are decision-free with no shared-resource problems. The outer loops involve shared-resources, parts dispatching, and route selection, and so require a conflict resolution command input, uc. The decision-making input uc is selected based on an agent-oriented paradigm. This paradigm views the production process in an automated manufacturing facility as distributed among autonomous manufacturing agents. The payoff matrix representation and operations research techniques are used to facilitate the agents’ decision making. This paper shows how the matrices depicting the decision-making situations of manufacturing agents can be arrived at. An example with a reentrant flow system characteristic for semiconductor manufacturing plants is provided.     

DCOM and MMS–based control software architecture for automated manufacturing system

In this paper, we introduce the manufacturing message specification (MMS) and compare two distributed object approaches–distributed component object model (DCOM) and common object request broker architecture (CORBA), suggest characteristics that DCOM is more suitable for automated manufacturing system (AMS) control software integration. In order to make a control system provided with interoperability and reconfigurability etc., a hybrid control system is built for AMS, then a control software architecture is presented for AMS based on distributed object DCOM middleware and MMS standard. The object-oriented DCOM communication protocol is used to implement the MMS in a distributed object mode. DCOM and MMS combination brings the operating system independent communication capabilities to manufacturing devices such as CNC machine tools and industrial robots in AMS. Control software implementation of MMS concepts in the DCOM environment is particularly discussed. Finally, to verify the control software architecture for AMS, prototype development has been implemented in VC++ 6.0 developer environments.     

Efficient deadlock prevention policy in automated manufacturing systems using exhausted resources

To design supervisors enforcing liveness of automated manufacturing systems (AMS), an efficient deadlock prevention policy based on the exhausted resources is proposed. This policy exploits a special structure of Petri nets in the sense that the liveness of a specific system can be guaranteed if no shared resource can be emptied. In contrast to the typical conventional policies, the explicit enumeration of either the reachable states or the siphons can be avoided. Experimental results verify the efficient implementation of the proposed policy.     

On an iterative deadlock prevention approach for automated manufacturing systems

In Hu (Transactions of the Institute of Measurement and Control 33:59–76, 2011), Petri nets are utilized to describe, analyse and control automated manufacturing systems (AMS). In order to suppress deadlock occurrences in AMS, a method to derive the bad markings iteratively using a mixed integer programming-based algorithm is proposed. To validate the effectiveness and efficiency of the proposed approach, two examples were demonstrated in Hu (Transactions of the Institute of Measurement and Control 33:59–76, 2011). This paper shows that the uncontrolled Petri net model in one of the examples is incorrect. It is also shown that the structural complexity of the computed monitors for both examples can be reduced with the same or more permissive system behaviours.     

A functional-to-behavioural transformation framework for specification and design of manufacturing systems

To maximize the productivity, quality and safety of operators, design and dependability analysis tools must be integrated as soon as possible in the lifecycle of automated manufacturing systems (AMS). As a concurrent approach, the structured analysis and design technique (SADT) can be efficiently used for such integration. SADT is a graphic notation for system specification and requirement analysis that is well adapted to describe the functions and their interconnection in a manufacturing systems. In spite of its advantages, SADT is limited by the lack of a formal foundation, which makes it necessary to extend it by a mathematical behavioural model such as the Petri net. This article first proposes an approach for the automatic generation of the Petri net model corresponding to SADT specifications, thus allowing a direct simulation of the SADT model to validate its behaviour. The complexity and non user-friendly interface of such a Petri net have led us to propose a temporal SADT whose primitives represent abstract types for the underlying Petri net model. This temporal SADT has the merits of both the SADT and Petri nets, since it adds to the user friendliness of SADT, the foundation of Petri nets.     

Comments on “Efficient deadlock prevention policy in automated manufacturing systems using exhausted resources”

As reported by Hu and Li (International Journal of Advanced Manufacturing Technology 40:566-571, 2009), in order to design liveness-enforcing supervisors for automated manufacturing systems (AMS), a deadlock prevention policy was proposed based on the exhausted resources. The proposed policy exploits a special structure of Petri nets for the liveness of a specific system. In order to show the applicability of this method, two examples were considered. One of the examples involves an AMS with a large-state space. Unfortunately, the liveness-enforcing supervisor containing seven monitors (control places) computed as reported by Hu and Li (International Journal of Advanced Manufacturing Technology 40:566-571, 2009) to enforce liveness on this system does not provide a live behaviour. This paper reports this fact.     

基于多色集合的敏捷制造系统重构方法

为了在满足客户需求的同时降低制造系统的生产成本,以敏捷制造系统的资源重构为研究对象,提出了基于多色集合理论的系统重构建模与重构方案评价方法。利用元素、个人颜色、统一颜色等概念,建立制造资源与系统功能的映射关系,通过搜索围道布尔矩阵获得系统重构方案。以此为基础,给出了基于系统功能冗余度的重构方案评价指标计算方法。实例验证结果表明,该建模方法简便易行,便于形式化表述和软件实现。     

A Classification for Hoist Scheduling Problems

Electroplating lines are totally automated manufacturing systems that are used to cover parts with a coat of metal. They consist of a set of tanks between which the parts to be treated are transported by one or several hoists. Scheduling the movements of these hoists is commonly called a hoist scheduling problem (HSP) in the literature. But the assumptions and constraints that must be taken into account greatly depend on the production environment (physical system, manufacturing specifications, and management policies). Consequently, there exist several classes of HSPs. The systematic frameworks usually used to classify deterministic scheduling problems do not allow distinguishing between these various kinds of HSPs. Therefore, identifying the scope of each published work and comparing the various proposed scheduling methods turn out to be difficult. Thus, this article presents notation for scheduling problems in electroplating systems, to make the specification of problem types and the identification of studied problem instances easier. An associated typology gives a survey of the literature and demonstrates the usefulness of the proposed classification scheme.     

AGV schedule integrated with production in flexible manufacturing systems

Flexible manufacturing systems (FMS) comprise, automated machine tools, automated material handling, and automated storage and automated retrieval systems (AS/RS) as essential components. Effective sequencing and scheduling of the material handling systems (MHS) can have a major impact on the productivity of the manufacturing system. The material handling cannot be neglected while scheduling the production tasks. It is necessary to take into account the interaction between machines, material handling systems and computer. In this context, this paper attempts to link the operation of automated guided vehicles (AGV) with the production schedule and suggests a heuristic algorithm that employs vehicle dispatching rules (vdr) for conflict resolution. The vdrs considered in this paper are: shortest operation time (SPT), longest operation time (LPT), longest travel time (LTT) and shortest travel time (STT). The performance of the vdrs in the proposed heuristic is compared with makespan criteria. The results show that the STT provides the best solutions compared to other vdrs.     

Producer’s behavior analysis in an uncertain bicriteria AGV-based flexible jobshop manufacturing system with expert system

Here, an approach for finding an optimal path in a flexible jobshop manufacturing system considering two criteria of time and cost is proposed. A network is configured in which the nodes are considered to be the shops with arcs representing the paths among the shops. An automated guided vehicle functions as a material handling device through the manufacturing network. To account for uncertainty, time is considered to be a triangular fuzzy number and apply an expert system to infer the cost. The expert system based on fuzzy rule backpropagation network to configure the rules for estimating the cost under uncertainty is proposed. A multiple linear regression model is applied to analyze the rules and find the effective rules for cost estimation. The objective is to find a path minimizing an aggregate weighted unscaled time and cost criteria. A fuzzy dynamic programming approach is presented for computing a shortest path in the network. Then, a comprehensive economic and reliability analysis is worked out on the obtained paths to find the optimal producer’s behavior. Finally, an application of the model is illustrated by a numerical example. The results show the effectiveness of our approach for finding an optimal path in a manufacturing system under uncertainty.     

Real-Time Deadlock Detection and Recovery for Automated Manufacturing Systems

The deadlock problems of automated manufacturing systems (AMS) are discussed in this paper. A dynamic-edge graph (DEG) with double labels was designed to model the AMS, to identify distinct part flows, to represent the states and capture the concurrent behaviour of the AMS. In the AMS, we assume that each resource has its own unit-capacity buffer to which it can be transferred when a deadlock situation occurs. The motivation of this research was to define the state of each part and propose a simple, dynamic and adaptable approach, based on double labels and some basic concepts in graph theory, for detecting a deadlock in real time and resolving deadlocks in the AMS. Through this approach both the utilisation of resources and the overall throughput can be improved. The proposed algorithmic procedure, in accordance with the states arrived at and generated from the model, can serve as a functional module for the operation of an AMS without the need to revise the original control extensively. In addition, the proposed procedure can be used cooperatively with a dispatching controller and expanded with little modification. ID="A1"Correspondance and offprint requests to: Dr W.-C. Yeh, Department of Industrial Engineering, Feng Chia University, PO Box 67-100, Taichung, Taiwan 407. E-mail: wcyeh@fcu.edu.tw     

On a maximally permissive deadlock prevention policy for automated manufacturing systems by using resource-oriented Petri nets

It is theoretically and practically significant to synthesize a maximally permissive (optimal) controller to prevent deadlocks in an automated manufacturing system (AMS). With an AMS being modeled with Petri nets, by the existing methods, integer linear programming (ILP) problems are usually formulated and solved to obtain optimal policies by forbidding illegal markings at the same time no legal marking is excluded. Without an efficient technique for solving an ILP, such a method is usually computationally prohibitive. A resource-oriented Petri net (ROPN) is employed to model a class of AMS for resolving the deadlock control problem with maximal permissiveness in this paper. Efficient methods are developed to figure out the key structures in an ROPN model for deadlock prevention. Based on the structural properties of ROPN models, this work explores several types of illegal markings that can be prohibited optimally by structural analysis. For these markings, a deadlock prevention policy can be derived in an algebraic way without solving a notorious ILP problem. For the other markings, linear programming (LP), instead of ILP, approaches are developed to forbid them optimally. Thus, a maximally permissive controller can be developed while the computational cost is reduced greatly. The proposed methods are verified by typical examples in the literature.     

An operational measure of routing flexibility in a multi-stage multi-product production system

The high degree of variety in customer demands causes mass production to become outdated and flexible production to be favored. Routing flexibility can be found in systems that implement general-purpose machines, alternative or identical machines, redundant machine tools, or the versatility of material handling systems. It is recognized that routing flexibility can be treated as a tool for enhancing system performance, such as lead time and inventory reduction. However, its implementation entails a huge cost of installation of flexible machines, automated tool changers and fixtures, and machine operators possessing multiple skills. Therefore, system managers must determine the appropriate level of routing flexibility for a specific system configuration in order to balance benefits and costs incurred. This paper presents a background to and a rational for a routing flexibility measure for a multi-stage flow shop. Instead of merely counting the number of available routes, this measure takes into account the loading balance between machines. Therefore, a manufacturing system with overloaded machines will have less routing flexibility as compared with one that is not overloaded, when both systems have the same number of available routes. An example for demonstrating the applicability of the proposed measure is also illustrated.     

Intelligent scheduling of automated machining systems

An automated machining system involves concurrent use of manufacturing resources, alternative process plans and flexible routings. High investment in the installation of automated facilities requires an efficient scheduling system that is able to allocate the resources specified for operations over a scheduling horizon. The primary emphasis of this paper is to generate schedules that accurately reflect details of the automated environment and the objectives stated for the system. In this paper, a rule for dispatching operations, named the Most Dissimilar Resources (MDR) dispatching rule, is introduced. A scheduling algorithm for automated machining is presented. Using the previous simulation research for this topic, a rule-based scheduling system is constructed. An architecture for an intelligent scheduling system is proposed, and the system has a high potential to provide efficient schedules based on the task-specific knowledge for the dynamic scheduling environment.     

Cyber-enabled concurrent material and process selection in a flexible design for manufacture paradigm

This paper presents a cyber design for manufacturing (DFM) framework for concurrent material and process selections. An internet-of-things (IoT) interface is developed wherein design, material, and process databases are accessed in a cloud-based environment. Digital designs are processed to extract dimensional features and functional requirements. A Node-RED IoT simulator is developed to provide seamless interconnectivity to translate design specifications with material and process databases via web sockets. The output from the cloud system is incorporated within a decision-making algorithm. The analytical hierarchy process (AHP) is implemented where alternatives are hierarchically compared to generate weights based on combinatorial order ranking of the designer preferences. A material-process index (MPI) is developed that integrates the material and process generated weights with material-process compatibility for selecting the optimal material and process combination. The proposed methodology is applied to an electrical power distribution interchangeable fuse cutout system to validate the approach. Material and processes are selected on a standalone basis without considering their compatibilities. Further, the MPI function is implemented that integrates functional preferences for material, process, and their compatibilities to contrast against standalone material and process selections. The material-process combination with the highest MPI was chosen as the optimal solution for a product design. The cyber DFM methodology developed in this research can be extended to different application domains based on flexible user chosen criteria.     

KBSES: A knowledge-based system for equipment selection

In this paper, a knowledge-based system KBSES for the selection of production equipment, i.e. machine tools and material handling carriers in an automated manufacturing system, is presented. Existing expert systems which have been applied to the selection of material handling carriers are briefly reviewed. A new model for the selection of production equipment is presented. The knowledge-based system developed has a tandem architecture and closely interacts with a set of models and algorithms. The components of the system are discussed. An illustrative example is included. Directions for further research are also provided.     

Dispatching and Conflict-Free Routing of Automated Guided Vehicles: An Exact Approach

This article presents an exact solution approach for the problem of the simultaneous dispatching and conflict-free routing of automated guided vehicles. The vehicles carry out material handling tasks in a flexible manufacturing system (FMS). The objective is to minimize the costs related to the production delays. The approach is based on a set partitioning formulation. The proposed model is solved to optimality by a column generation method, which is embedded in a branch-and-cut exploration tree. The proposed model and solution methodology are tested on several scenarios with up to four vehicles in the manufacturing system. The results show that most of these scenarios can be solved to optimality in less than three minutes of computational time.     

Development of a generative CAPP system for axisymmetric components for a job shop environment

Process planning is a function in a manufacturing organization that selects the manufacturing processes and parameters to be used to transform a part from its initial state to the final form according to the design specifications. It is a bridge between product design and product manufacturing. The activities of process planning include understanding the part specifications or product design data, selection of job material and tool, setup planning, sequencing the operations within a setup, determination of process parameters for each operation, and generation of process sheets. This paper outlines a method to develop a generative computer-aided process planning system for axisymmetric components for a job shop environment. A decision support system is used to perform semi-structured tasks such as setup planning and establishing precedence relationship among various operations.     

现代制造科学的新发展

２１世纪的制造面临着市场,信息,环境和资源的严峻挑战,先进制造技术必须面对这种挑战。现代制造是先进制造技术的理论基础,它的灵魂和生命在于创新,现代科学创新往往产生在学科交叉中,因此,开展多学科交叉研究是现代制造科学发展的源泉。现代制造科学是微电子,计算机,自动化,网络通信等信息科学,管理科学,生命科学与机械工程和制造科学的交叉,中国国家自然科学基金的任务是鼓励和晕种交叉研究,发展和完善现代制造科学     

敏捷制造系统中产品信息和访问控制模型研究

研究了敏捷制造系统中产品信息建模和访问控制建模的理论和方法,提出了面 向对象的分解准则。并阐述了本文所提出的产品信息模型和访问控制模型具备可重 构性和可重用性,能够满足制造系统敏捷性要求。