Project Management Institute Automation Systems Specific Interest Group

Basic Building Blocks in Automation at the Work Station Level

We can talk about components as primarily belonging to one of the following classes:

1. Sensors
2. Analyzers
3. Actuators
4. Drives

Sensors
Sensors are the first link between the typical automated system and the conventional process. Sensors convey information from the manufacturing process equipment, the piece part being manufactured, and from the human operator, if any. It may seem strange that the automated system senses the human operator, but this is without doubt the most important link between the automated system and the real world. Sensors can be as follows:

• Manual Switches
• Limit Switches
• Proximity Switches
• Photoelectric Sensors
• Infrared Sensors
• Fiber Optics
• Lasers

Analyzers
Once information is sensed by an automated system, it must be registered and analyzed for content, and then a decision must be made by the system as to what action should be taken. This function can be quite complex, and the system components that perform it are generally too complicated to discuss in detail here. But some of the components deserve mention here to enable you to understand the components of NC machines, robots, programmable controllers, and other manufacturing automation devices discussed.

• Computers
• Counters
• Timers
• Bar Code Readers
• Optical Encoders

Actuators
Once a real-world condition is sensed and analyzed, something may need to be done about it. It is at this point that the automation of many systems ceases because it is believed that a human operator must intervene and apply judgment for taking some kind of physical action. Such systems may be called "process monitoring" if they merely sense and display or record data or "on-line assist" if they also analyze data and give advice or prompts to the operator suggesting specific actions to be taken. However, more and more automated systems are closing the loop by taking physical action automatically without operator intervention.

Actuation may be a direct physical action upon the process, such as a sweep bar that sweeps items off a conveyor belt at the command of a computer or other analyzer. In other cases, an actuator is simply a physical making of an electrical circuit, which in turn has a direct effect upon the process. An example would be an actuator (relay) that turns on power to an electric furnace heating circuit. Examples are:

• Cylinders
• Solenoids
• Relays

Drives
Like actuators, drives take some action upon the process at the command of a computer or other analyzer. For purposes of classification, the distinction being made here between actuators and drives is that actuators are used to effect a short, complete, discrete motion - usually linear - and drives execute more continuous movements typified by, but not limited to, rotation. Actuators may turn drives on and off, and drives may provide the energy for the movement of actuators. Some automation devices, such as genevas and walking beams, seem to belong to both categories. Examples of drives are:

• Motors
• Stepper Motors
• DC Servo Motors
• Kinematic Linkages
• Genevas
• Walking Beams

In summary, the above has provided the "nuts and bolts" of mechanization and automation. Automation begins with a simple and sometimes not so simple mechanization of portions of the operation of individual work stations. Although it is wise to keep the systems approach in mind for total automation of a factory, plant or enterprise, in reality most factories are automated a piece at a time.

It is difficult to classify the components of mechanization and automation, but broad categories have been offered up. By describing types of integrated automation systems and their utility in manufacturing/processing, we have at least begun the educational process.

The purpose for this SIG is to help non-automation industry folks and project managers understand more and in turn, help automation systems industry folks to understand the demands of project management in automation systems projects. Since we generally accept the premise that 95% (or more?) of all failures (and successes) in projects are people-related, and not technology-related, the goal here is excellence in the project management of automation projects.