Sivaram Balasubramanian

Bidding-based process planning and scheduling in a multi-agent system

Abstract Effective and efficient implementation of intelligent and/or agile manufacturing systems requires an enterprise level integration. The first step in this direction is to integrate design, process planning and and scheduling. This paper describes a bidding-based approach to the integration of computer-aided design, process planning and real time scheduling. The product is represented in a STEP model with detailed design and administrative information including design specifications, batch size, and due dates. Upon arrival at the manufacturing facility, the product is registered in the shop floor manager which is essentially a coordinating agent. The shop floor manager broadcasts the products requirements to the machines. The shop contains autonomous machines that have knowledge about their functionality, capabilities, tooling and schedules. Each machine has its own process planner and responds to the products request in a way that is consistent with its capabilities and capacities. When more than one machine offers certain process(es) for the same requirements, they enter into negotiation. Based on processing time, due date and cost, one of the machines wins the contract. The successful machine updates its schedule and advises the product to request raw material for processing. The concept was implemented using a multi-agent system in an object-oriented programming language. The task decomposition and planning are achieved through contract nets. Examples are included to illustrate the approach.

MULTI-AGENT PLANNING AND COORDINATION FOR DISTRIBUTED CONCURRENT ENGINEERING

The centralized planning and control that has defined the traditional information processing structure of manufacturing systems is no longer suited to the current rapidly changing manufacturing environment. For efficient use of manufacturing resources and increased flexibility, it is necessary to migrate to a distributed information processing system in which individual entities can work cooperatively towards overall system goals. The next generation of manufacturing systems requires such an information technology framework to integrate the system components and activities into a larger collaborative enterprise. This paper describes a multi-agent approach to concurrent design, manufacturability analysis, process planning, routing and scheduling. A heterogeneous multi-agent concurrent engineering system consisting of multiple feature-based design sub-systems, multiple simulated shop-floor resource groups, a supervisory control interface and the coordination mechanisms for multi-agent cooperation, has been developed. The architecture of this distributed system and the associated implementation issues are discussed.

Design and implementation of a real-time holonic control system for manufacturing

Abstract This paper describes a new approach to low-level process/machine control for manufacturing that is based on the holonic manufacturing systems (HMSs) paradigm. The primary motivation for this work is the requirement for manufacturing systems that can automatically and intelligently adapt to changes in the manufacturing environment while still achieving overall system goals. To meet this requirement, a low-level architecture for distributed process/machine control is described that is dynamically reconfigurable and supports distributed applications based on the IEC-1499 function block (FB) standard. To evaluate the feasibility of this new approach, a prototype system based on this architecture is described and performance results are reported.

Agent-based control system for next generation manufacturing

Future manufacturing systems will be required to be agile, flexible and fault-tolerant. The next-generation intelligent manufacturing systems will be multi-agent systems containing distributed control and application entities that dynamically collaborate to satisfy both local and global objectives. This paper focuses on the development of a generic control system design based on IEC-1499 function block standards, for real-time distributed manufacturing environments. The paper first describes the related research into the control system architecture using multi-agent cooperation, then reports on the intelligent controller design interface and automatic control code generation.

Dynamic control architecture for metamorphic control of advanced manufacturing systems

While current research into decentralized control architectures for advanced manufacturing systems has proven the concept of architectures ranging from hierarchical to heterarchical control, neither extreme of the control architecture spectrum has proven to be the most appropriate choice for given manufacturing systems. This paper reports on research into a control architecture that does show promise in this area: a hybrid control architecture consisting of elements of both hierarchical and heterarchical control architectures. First control architectural issues are considered. Next, the concepts of virtual control organizations and partial dynamic hierarchies are presented. The paper then concludes with a discussion of recent work on implementing partial dynamic hierarchies within real-time control constraints, using an agent-based architecture.

A Multiagent Architecture for Concurrent Design, Process Planning, Routing, and Scheduling

A concurrent engineering system has been developed using a multiagent architecture to address the issues of design, manufactur ability analysis, incremental process planning, dynamic routing, and scheduling simultaneously The system includes a feature-based intelligent design subsystem for prismatic components, a shop-floor subsystem to represent available resources, and a supervisory control interface to manage the shop-floor resources The evaluation of the system used a simulated shop-floor environment with four production machines for the design of a prismatic component. As the design progressed, manufacturability was evaluated and shop-floor planning was carried out concur rently Valid process plans, routing, and scheduling were generated The system is now being extended to incorporate additional design systems and shop-floor environments

Requirements for holonic manufacturing systems control

Real time control of holonic manufacturing systems requires a radically different approach from that of traditional unit level regulatory control. Because they need to automatically adapt and reconfigure based on the ever changing requirements of the manufacturing system, control systems based on this approach are termed metamorphic control systems. The engineering of such software centric metamorphic control systems for dynamically reconfigurable distributed multi sensor based holonic systems is addressed. An integrated and uniform event driven control architecture is specified for various functional levels of metamorphic control system. This architecture utilizes the emerging International Electrotechnical Commission function block standard (IEC 1499) for industrial process measurement and control systems to specify the requisite behavior of distributed control software components (agents).

Intelligent multi-agent coordination system for advanced manufacturing

Global competition and rapidly changing customer requirements are forcing major changes in the production styles and configuration of manufacturing organizations. Agent-based systems are showing considerable potential as a new paradigm for agile manufacturing systems. With this approach, centralized and sequential manufacturing planning, scheduling, and control systems may be replaced by distributed intelligent systems to facilitate flexible and rapid response to changing production styles and variations in product requirements. In this paper, the characteristics and components of such a multi-agent architecture for advanced manufacturing are described. This architecture addresses agility in terms of the ability of the manufacturing system to solve manufacturing tasks using virtual enterprise mechanisms while maintaining concurrent information processing and control.

Bidding-based autonomous process planning and scheduling

Improving productivity through computer integrated manufacturing systems (CIMS) and concurrent engineering requires that the islands of automation in an enterprise be completely integrated. The first step in this direction is to integrate design, process planning, and scheduling. This can be achieved through a bidding-based process planning approach. The product is represented in a STEP model with detailed design and administrative information including design specifications, batch size, and due dates. Upon arrival at the manufacturing facility, the product registered in the shop floor manager which is essentially a coordinating agent. The shop floor manager broadcasts the products requirements to the machines. The shop contains autonomous machines that have knowledge about their functionality, capabilities, tooling, and schedule. Each machine has its own process planner and responds to the products request in a different way that is consistent with its capabilities and capacities. When more than one machine offers certain process(es) for the same requirements, they enter into negotiation. Based on processing time, due date, and cost, one of the machines wins the contract. The successful machine updates its schedule and advises the product to request raw material for processing. The concept was implemented using a multi-agent system with the task decomposition and planning achieved through contract nets. The examples are included to illustrate the approach.