Manufacturing system

Definition of manufacturing system

1. A manufacturing system can be defined as the arrangement and operation of machines, tools, material, people and information to produce a value-added physical, informational or service product whose success and cost is characterized by measurable parameters.

2. A manufacturing system is an approach to making products that is based upon several factors. These include how much of the product is needed, how quickly the product must be produced and how unique the product must be to ensure sufficient sales. Manufacturing systems include custom, assembly, flexible, intermittent, reconfigurable, just-in-time and lean manufacturing systems.

Decision hierarchy of industrial information system

Level 1: Machine

CNC machine toolsRobotsProgrammable controllers

Level 2: Work cell/ Production line

Inspection/ SPCMaterials handlingPart sequencing

Level 3: Factory Floor

Materials managementMaintenance managementShop floor schedulingQuality management

Level 4: Plant Order processingPurchasingAggregate production planningAccounting

Level 5: Distribution

Transportation planningSupply chain inventory controlDemand forecasting

ERP

MES

CONTROLS

1. The machine control level is responsible for ensuring that the sequence of machine operations corresponds to the planned sequence necessary to fabricate the part. Typically, the sequence of operations is carried out as prescribed by the program resident in the machine controller, and there are few, if any, decisions to be made.

2. the production line or work cell level, the objective is to supervise the interactions between a group of related machines or processes. This level of decision making is not concerned with the operation of the machine or process. The emphasis here is on the release and delivery of materials to a machine in the work cell at the correct time.

3. the factory floor level, decisions are made that affect groups of production lines or work cells. For example, several production lines or work cells may be serviced by the same materials management system that requests the movement of raw materials from storage to production so that they can be manufactured into a finished product.

4. the plant level, decisions are less concerned with the daily operation of the factory and are more closely related to the business planning objectives of the fi rm. A typical plant-level production control decision is aggregate production planning, which refers to the process of planning the use of the plant’s production capacity to meet customer demands over a period of months or a year. The output of this plan is a master schedule of what products will be produced during each period of time going forward over the planning horizon of the plan.

5. the distribution system level the emphasis is on coordinating the supply of finished product to the end customer. Maintaining appropriate and cost-effective inventory levels, as well as managing the transportation of product between warehouse locations in the supply chain, is a problem addressed at this level.

Coordinating the layers of the system

Control LayerProcess set point control Process monitoringMachine tool control Cell controlIoT Senso

rControll

er

MESOperation scheduling Lot traceabilityProduction dispatching Quality controlWork in process status Maintenance managementData acquisition

CCsHiCs

HeCs

ERP

Forecasting Production planning Inventory controlCosting Purchasing Recipe managementTransportation Supply chain management

What was produced

Real time actual results

What to produce

How to manufacture

ERP: Enterprise resource planning (ERP) is business management software—usually a suite of integrated applications—that a company can use to collect, store, manage and interpret data from many business activities, ERP provides an integrated view of core business processes, often in real-time, using common databases maintained by a database management system. ERP systems track business resources—cash, raw materials, production capacity—and the status of business commitments: orders, purchase orders, and payroll.

MES: Manufacturing Execution Systems (MES) are computerized systems used in manufacturing. MES can provide the right information at the right time and show the manufacturing decision maker "how the current conditions on the plant floor can be optimized to improve production output." MES work in real time to enable the control of multiple elements of the production process (e.g. inputs, personnel, machines and support services).

Manufacturing Execution System

MRP/MRP II/ERP are generally thought of as “planning” systems. They are responsible for supporting the planning of production, but they are not very well integrated into the execution of production. This void in available software solutions on the shop floor has led to the development of the manufacturing execution system (MES). The MES is an attempt to manage resources, including materials, machines, and personnel, on a daily or even hourly basis. Typical MES functions include the following:

Dispatching and monitoring production

Detailed scheduling associated with specific production units in order to meet specific performance criteria.

Data collection from factory floor operation to provide a history of factory events.

Quality data analysis

Product history recording

Computer integrated Manufacturing

Computer-integrated manufacturing (CIM) is the manufacturing approach of using computers to control the entire production process. This integration allows individual processes to exchange information with each other and initiate actions. Through the integration of computers, manufacturing can be faster and less error-prone, although the main advantage is the ability to create automated manufacturing processes. Typically CIM relies on closed-loop control processes, based on real-time input from sensors. It is also known as flexible design and manufacturing

CIM

http://www.technologystudent.com/rmprp07/intman1.html

NETWORK ARCHITECTURE

The network architecture is a description of how the various layers of the decision hierarchy will communicate with one another. The network architecture is typically implemented with the use of local area networks. A local area network (LAN) is a communication network that is implemented over a limited area and is usually owned by one organization. It is a common medium that allows several computers or several machine controllers to be connected, and, as long as each computer uses the protocol convention of the LAN, communication can take place at high data rates.

Figure 1.4 shows a typical example for a modern industrial company. This architecture shows three distinct layers. At the bottom, the physical processes of manufacturing on the shop floor are arranged in stations along a production line or in manufacturing cells. Controllers that are dedicated to those physical processes control the operations at each station. These controllers may be computers, but they are more likely special-purpose computers, called programmable logic controllers (PLC), which have been specifi cally designed to control and collect formation from machinery.

Historically, manufacturers of machine controllers have implemented communication requirements using local area networks designed specifically for their own controllers. In Figure, we are assuming that the controllers have the capability of communicating with each other over a common local area network, sometimes called a shop floor data highway. Such communication capability allows individual machines to “talk” to one another as peers. This is known as “peer to-peer” communication capability. So, for example, if a machine at one station has a failure, the controller at that station can transmit that information to other stations or to the supervisory controller, which may respond by stopping the processes and signaling for assistance.

Another distinct layer of the architecture is the business layer, at which functional departments are connected to one another via computers and a local area network. The factory host computer is the repository of data for factory operation. The individual functions shown are the high-level business and planning functions of the factory. In Figure, these functions are interconnected Figure Typical network architecture. 8 Introduction with each other and the factory database over their own local area network. The distinction between the shop floor LAN and the business-level LAN is one that has developed in practice over time because of differences in the communication performance requirements at each level as well as available LAN options on the factory floor.

Manufacturing Control - Managing and controlling the physical activities in the factory aiming to execute the manufacturing plans. Normally, a manufacturing control comprises the short-term process plan and the shop floor activities.

Three indicators for testing a manufacturing execution system

Agility - Capability to react in a short period of time to the occurrence of unexpected disturbances (i.e. production environment changes).

Flexibility - Capability to adapt to new, different or changing environments. In manufacturing world, several flexibility classifications are presented in literature, like mix, changeover, volume, product and sequencing.

Re-configurability - Ability to support different manufacturing system configurations, i.e. different production systems scenarios, with a small customization task.

Traditional Manufacturing execution Approaches

Centralized Control Structures

is characterized by a single decision node, where all the planning and processing information functions are concentrated.

Advantage: a better management and control optimization

Disadvantage: low, speed of response, control complexity, tolerance to faults and expandability, specially for large systems.

Hierarchical Control Structures

Hierarchical Control Structures

In the hierarchical architecture, a complex problem is decomposed in several simpler and smaller problems, and distributed among multiple control layers. This architecture is characterized by the existence of some control levels, distributed in a tree structure, allowing the distribution of decision-making among these hierarchical levels. The relations between hierarchical levels are based on the master-slave concept.

Advantage: The main advantages of this architecture are the robustness, the predictability and the efficiency that are better than in centralized architectures.

Disadvantage: the appearance of disturbances in the system reduces significantly its performance.

Heterarchical Control Structures

The heterarchical architecture, also designated by autonomous agent approach in the agent domain, is characterized by the high level of autonomy and co-operation, being the client-server structure with fixed relations no more applied.

Advantage: allow a high performance against disturbances, The expandability of the system is an easier task, because it is enough to modify only the functioning of some modules or add new modules to the control system.

Disadvantage: is a novel technology, needs more research works, at the time the implementation of this control structure is not common

What is agent An agent is a computer system that is

capable of independent ( autonomous) action on behalf of its user or owner (figuring out what needs to be done to satisfy design objectives, rather than constantly being told).

An example: Spacecraft Control

When a space probe makes its long flight from Earth to the outer planets, aground crew is usually required to continually track its progress, and decide how to deal with unexpected eventualities. This is costly and,

robot soccer team

A team of robotic soccer players play a game against another robotic soccer team

Robots should cooperate with teammates, but should compete with adversaries to win the game

https://www.youtube.com/watch?v=YI9xnZ9msn8

The main characteristics of these agents are

Autonomy, because agents should be able to perform most of their tasks without the direct intervention of humans and should have a degree of control over their own actions and their own internal state.

Social ability, because agents should be able to interact with other software agents and humans

Responsiveness, agents should perceive their environment and respond in a timely fashion to changes occurring there

Pro activeness, agents do not simply act in response to their environment, they are able to exhibit goal-directed behavior by taking the initiative."

Adaptability, meaning that the agent should be able to modify its behavior over time in response to changing environmental conditions and to an enhanced knowledge about its problem-solving role

Mobility, because the agent should possess the ability to change its physical location to improve its problem-solving capacity

Rationality, because an agent should be expected to act in order to achieve its goals and not to prevent its goals from being achieved without good cause

Nwana gave yet another perspective on the agent paradigm. The main characteristics an agent should exhibit have been identified in a set of three attributes:

autonomy, cooperation, and learning.

Multi agent system A multi agent system is a system in which a number

of agents interact with each other. In the most general case, agents will be acting on

behalf of users with different goals and motivations. To successfully interact, they will require the ability to cooperate, coordinate, and negotiate with each other, much as people do.

Agent Models

1. Basic model of an agent

2. Reactive agents

3. Deliberative agent

4. Hybrid agent

5. ...

6. …

Multi Agent System Design Methodologies

1. Extensions of Knowledge-Oriented Methodologies

2. Extensions of Object-Oriented and Manufacturing Methodologies

3. Role-Based Methodologies

4. System-Oriented Methodologies

5. Interaction-Oriented Methodologies

6. Behavior-Oriented Methodologies

Extensions of Knowledge-Oriented Methodologies

The knowledge-oriented methodologies proposed for designing agent based systems are mostly extensions of the knowledge engineering methodology CommonKADS (Schreiber et al. 1994). These methodologies adopt the CommonKADS approach and add agent-oriented concepts to it. There are two examples of knowledge-oriented methodologies for agent based systems, CoMoMAS and MAS-CommonKADS.

Extensions of Object-Oriented and Manufacturing Methodologies

Burmeister (1996) extends the object oriented methodologies to agent oriented analysis by introducing mental and co-operation concepts. As in object-oriented analysis, she proposes three models which can be developed in parallel:

1. The agent model contains agents and their internal structure, described in terms of mental notions such as goals, plans and beliefs or similar concepts.

2. The organizational model specifies the relationships among agents and agent types. Organizational relationships can be inheritance or role based as in real organizations.

3. The co-operation model describes the interaction (or more specifically the co-operation) among agents.

Example PROSA Van Brussel et al. (1999) propose a methodology for identifying

manufacturing agents based on the object-oriented approach and the PROSA framework. The PROSA framework consists of product, resource and order agents, which may be supported by staff agents. These agents can be aggregated or specialized in the object-oriented sense in order to create a taxonomy of agents for a specific manufacturing application.

Step by step

1. Identification of the agents and their responsibilities in the specific manufacturing application.

2. The identification process is guided by the PROSA framework and starts with an object-oriented model of the manufacturing system.

3. The designer then selects the objects in this model which should become agents, even though the methodology does not provide any criteria for identifying suitable objects.

4. The agents are classified in the PROSA framework by aggregating and specializing agents.

Case study: workflow management system

1. Management agent: A management agent provides the user interface for the human workflow manager. It can:

– Create and delete role definitions and process definitions

– Instantiate a new process instance

– Create resource agents for new resources

– Simulate the execution of a process.

2. Storage agent: A storage agent manages the persistent data, for instance the definitions of tasks, roles and processes, and the monitored data. It also notifies all management agents if the data has changed

3. Process agent: A process agent is responsible for the execution of one particular case

4. Resource agent: A resource agent is the user interface for the human resource or the interface for some tool which can do tasks automatically (such as printers and scanners). Every resource has its own resource agent.

5. Resource broker agent: A resource broker is responsible for the resource management. Every resource agent is registered with at least one of the resource brokers and a process agent requests the resource broker to identify and allocate a suitable resource.

6. Monitor agent: A monitor agent gathers the data in the system that is necessary to analyze workflows, such as execution times and resource utilization.

7. Control agent: A control agent) provides the feedback mechanism required for process re-engineering. The control agent continuously senses the anomalies or violations of the criteria specified by the manager and sends warning messages to the manager agent and also logs those messages.

Simple example To illustrate the functionality of the system, we chose a simple

process of ordering a book. After the customer orders a book, the inventory has to be checked whether a copy of this book is there and the credit rating of the customer has to be checked. These checks are done in parallel to speed up the process and afterwards the results are evaluated. Based on the evaluation it is decided whether the order can be processed or should be rejected. Assuming that the processing of the request has been approved, the shipping of the book and the sending of the bill are done in parallel. Finally the results of shipping and billing activities are archived so that one can handle possible customer complaints.

The sequence diagram for starting a new work case

The sequence diagram for allocating a resource and executing a task

Home Work

MAS production control system for manufacturing umbrellas

For more information: An RF-ID driven holonic control scheme for production control systems

A Short Description of Umbrellas

a large piece of cloth with a single RFID tag is colored in the dyeing process, and then it is transported to the cutting process, where it is sliced into pieces and where an RFID tag is attached to each piece of cloth. All of the tags of cut cloth receive the lifetime information from the original cloth's tag but are assigned a sequential sub-ID under the same component ID. Wire props, each with one RFID tag and a piece of cloth with a matching RFID tag, are processed into the final umbrella product during the wire prop attachment process, which is a joined process. Although the final product still has two attached RFID tags, only one of them, marked as “representative” is used in later stages.

RFID tag readers/writers are attached to the front and rear of production facilities to read RFID tags attached to the components. The process ID read from the tag is used to instruct conveyors to deliver the corresponding component to the desired process.

When each process is completed, the RFID tag reader/writer in the rear side updates the current status in the tag. If the order changes, the RFID tag reader/writer in the front side modifies the status in the tag to indicate a cancellation or increase or decrease in the number of products.