Module 4 Introduction to Automation.docx

Module 4 Introduction to Automation Module Content 1. Introduction 2. Learning Objectives 3. Discussion a. Basic Elements of an Automated System i. Power to Accomplish the Automated Process ii. Program of Instructions iii. Control System b. Advanced Au...

Module 4 Introduction to Automation Module Content 1. Introduction 2. Learning Objectives 3. Discussion a. Basic Elements of an Automated System i. Power to Accomplish the Automated Process ii. Program of Instructions iii. Control System b. Advanced Automation Functions iv. Safety Monitoring v. Maintenance and Repair Diagnostics vi. Error Detection and Recovery c. Levels of Automation 5. Review Questions 6. Task Assessment/ Problem Solving 7. Reference Automation can be defined as the technology by which a process or procedure is accomplished without human assistance. It is implemented using a program of instructions combined with a control system that executes the instructions. To automate a process, power is required, both to drive the process itself and to operate the program and control system. Although automation is applied in a wide variety of areas, it is most closely associated with the manufacturing industries. It was in the context of manufacturing that the term was originally coined by an engineering manager at Ford Motor Company in 1946 to describe the variety of automatic transfer devices and feed mechanisms that had been installed in Ford's production plants. It is ironic that nearly all modern applications of automation are controlled by computer technologies that were not available in 1946. The terms automation and mechanization are often compared and sometimes confused. Mechanization refers to the use of machinery (usually powered) to assist or replace human workers in performing physical tasks, but human workers are still required to accomplish the cognitive and sensory elements of the tasks. By contrast, automation refers to the use of mechanized equipment that performs the physical tasks without the need for oversight by a human worker. After completing this module, the students will be able to: 1. Discuss the basic elements of an automated system; 2. Explain the advance automation functions; and 3. Identify the level of automation. 1. Basic Elements of an Automated System An automated system consists of three basic elements: (1) power to accomplish the process and operate the system, (2) a program of instructions to direct the process, and (3) a control system to actuate the instructions. The relationship among these elements is illustrated in Figure 1. All systems that qualify as being automated include these three basic elements in one form or another. They are present in the three basic types of automated manufacturing systems: fixed automation, programmable automation, and flexible automation. a. Power to Accomplish Automated Process - Electric power is widely available at moderate cost. It is an important part of the industrial infrastructure. - Electric power can be readily converted to alternative energy forms: mechanical, thermal, light, acoustic, hydraulic, and pneumatic. - Electric power at low levels can be used to accomplish functions such as signal transmission, information processing, and data storage and communication. - Electric energy can be stored in long-life batteries for use in locations where an external source of electrical power is not conveniently available. b. Program of Instructions The actions performed by an automated process are defined by a program of instructions. Whether the manufacturing operation involves low, medium, or high production, each part or product requires one or more processing steps that are unique to that part or product. These processing steps are performed during a work cycle. A new part is completed at the end of each work cycle (in some manufacturing operations, more than one part is produced during the work cycle: for example, a plastic injection molding operation may produce multiple parts each cycle using a multiple cavity mold). The particular processing steps for the work cycle are specified in a work cycle program, called part programs in numerical control. Other process control applications use different names for this type of program. - Work Cycle program. In the simplest automated processes, the work cycle consists of essentially one step, which is to maintain a single process parameter at a defined level. - Decision Making in the Programmed Work Cycle. Each work cycle consisted of the same steps and associated process parameter changes with no variation from one cycle to the next. The program of instructions is repeated each work cycle without deviation. - Control Systems. The control element of the automated system executes the program of instructions. The control system causes the process to accomplish its defined function, which is to perform some manufacturing operation. 2. Advance Automation Function In addition to executing work cycle programs, an automated system may be capable of executing advanced functions that are not specific to a particular work unit. In general, the functions are concerned with enhancing the safety and performance of the equipment. Advanced automation functions include the following: (1) safety monitoring, (2) maintenance and repair diagnostics, and (3) error detection and recovery. a. Safety Monitoring One of the significant reasons for automating a manufacturing operation is to remove workers from a hazardous working environment. An automated system is often installed to perform a potentially dangerous operation that would otherwise be accomplished manually by human workers. However, even in automated systems, workers are still needed to service the system, at periodic intervals if not full time. Accordingly, it is important that the automated system be designed to operate safely when workers are in attendance. In addition, it is essential that the automated system carry out its process in a way that is not self-destructive. Thus, there are two reasons for providing an automated system with a safety monitoring capability: (1) to protect human workers in the vicinity of the system, and (2) to protect the equipment comprising the system. b. Maintenance and Repair Diagnostics Modern automated production systems are becoming increasingly complex and sophisticated, complicating the problem of maintaining and repairing them. Maintenance and repair diagnostics refer to the capabilities of an automated system to assist in identifying the source of potential or actual malfunctions and failures of the system. Three modes of operation are typical of a modern maintenance and repair diagnostics subsystem: - Status Monitoring - Failure Diagnostics - Recommendation of Repair Procedures c. Error Detection and Recovery In the operation of any automated system, there are hardware malfunctions and unexpected events. These events can result in costly delays and loss of production until the problem has been corrected and regular operation is restored. Traditionally, equipment malfunctions are corrected by human workers, perhaps with the aid of a maintenance and repair diagnostics subroutine. With the increased use of computer control for manufacturing processes, there is a trend toward using the control computer not only to diagnose the malfunctions but also to automatically take the necessary corrective action to restore the system to normal operation. The term error detection and recovery is used when the computer performs these functions. - Error Detection. The error detection step uses the automated system's available sensors to determine when a deviation or malfunction has occurred, interpret the sensor signal(s), and classify the error. Design of the error detection subsystem must begin with a systematic enumeration of all possible errors that can occur during system operation. The errors in a manufacturing process tend to be very application-specific. They must be anticipated in advance in order to select sensors that will enable their detection. - Error Recovery. Error recovery is concerned with applying the necessary corrective action to overcome the error and bring the system back to normal operation. The problem of designing an error recovery system focuses on devising appropriate strategies and procedures that will either correct or compensate for the errors that can occur in the process. Generally, a specific recovery strategy and procedure must be designed for each different error. 3. Levels of Automation Automated systems can be applied to various levels of factory operations (Figure 2). One normally associates automation with the individual production machines. However, the production machine itself is made up of subsystems that may themselves be automated. *Figure 2 Five levels of automation and control in manufacturing* 1. What is automation? 2. Name the three basic elements of an automated system. 3. What is the difference between a process parameter and a process variable? 4. What are the five categories of work cycle programs, as listed in the text? Briefly describe each. 5. What are three reasons why decision making is required in a programmed work cycle? 6. What is the difference between a closed-loop control system and an open-loop control system? 7. What is safety monitoring in an automated system? 8. What is error detection and recovery in an automated system? 9. Name three of the four possible strategies in error recovery. 10. Identify the five levels of automation in a production plant. Groover, M.P. (2015). *Automation, Production Systems, and Computer-Integrated Manufacturing* (4^th^ Edition): Pearson Higher Education, Inc\... Upper Saddle River, New Jersey.