AUTOMATION TECHNOLOGIES FOR MANUFACTURING SYSTEMS Flashcards
Define the term manufacturing system.
The text defines manufacturing system as a collection of integrated equipment and human resources that performs processing and/or assembly operations on a starting work material, part, or set of parts. The integrated equipment consists of one or more production machines, material handling and positioning devices, and computer systems.
What are the three basic components of an automated system?
The three basic components of an automated system, according to the text, are (1) power, (2) a program of instructions, and (3) a control system to carry out the instructions.
What are some of the advantages of using electrical power in an automated system?
Advantages listed in the text are (1) it is widely available, (2) it can be readily converted to other forms of power such as mechanical, (3) it can be used at lower power levels for signal processing, communication, and data storage, and (4) it can be stored in long-life batteries.
What is the difference between a closed-loop control system and an open-loop control system?
The difference is that a closed-loop control system includes feedback of data related to the output of the process that is used to make control adjustments. An open-loop system does not have this feedback loop.
What is the difference between fixed automation and programmable automation?
In fixed automation, the processing or assembly steps and their sequence are fixed by the equipment configuration. The program of instructions is determined by the equipment design and cannot be easily changed. In programmable automation, the equipment is designed with the capability to change the program of instructions to allow production of different parts or products.
What is a sensor?
A sensor is a device that converts a physical stimulus or variable of interest (e.g., temperature, force, pressure, or other characteristic of the process) into a more convenient physical form (e.g., electrical voltage) for the purpose of measuring the variable. The conversion allows the variable to be interpreted as a quantitative value.
What is an actuator in an automated system?
In automated systems, an actuator is a device that converts a control signal into a physical action, which usually refers to a change in a process input parameter. The action is typically mechanical, such as a change in position of a worktable or rotational speed of a motor.
What is a contact input interface?
As defined in the text, a contact input interface is a device that reads binary data into the computer from an external source.
What is a programmable logic controller?
As defined in the text, a programmable logic controller (PLC) is a microcomputer-based
controller that uses stored instructions in programmable memory to implement logic, sequencing, timing, counting, and arithmetic control functions, through digital or analog input/output modules, for controlling various machines and processes.
Identify and briefly describe the three basic components of a numerical control system.
The three basic components are: (1) part program, (2) machine control unit, and (3)
processing equipment. The part program is the detailed set of commands to be followed by the
processing equipment. The machine control unit in modern NC technology is a microcomputer that
stores the program and executes it by converting each command into actions by the processing
equipment, one command at a time. The processing equipment accomplishes the sequence of
processing steps to transform the starting workpart into a completed part.
What is the difference between point-to-point and continuous path in a motion control system?
In point-to-point, the motion is from one location in space to the next with no regard for
the path taken between starting and final locations. In continuous path, the trajectory of the
movement is controlled.
What is the difference between absolute positioning and incremental positioning?
In absolute positioning, the locations are defined relative to the origin of the axis system.
In incremental positioning, each succeeding location is defined relative to the previous location.
What is the difference between an open-loop positioning system and a closed-loop positioning
system?
In a closed loop system, measurements of the output (position) are fed back to verify that
it corresponds to the desired input value. In an open loop system, there is no feedback of the output
value.
Under what circumstances is a closed-loop positioning system preferable to an open-loop system?
When there is a significant reaction force resisting the motion of the positioning system, a
closed loop system is preferred.
Explain the operation of an optical encoder.
An optical encoder is a sensor for measuring angular position and rotational velocity. It
consists of a light source, a photodetector, and a disk containing a series of slots through which the
light source can shine to energize the photodetector. The disk is connected, either directly or
through a gear train, to a rotating shaft whose angular position and velocity are to be measured. As
the shaft rotates, the slots cause the light source to be seen by the photocell as a series of flashes,
which are converted into an equivalent series of electrical pulses. By counting the pulses and
computing the frequency of the pulse train, angular position and rotational speed can be determined.
