Jidoka - Automation and Mechanization - Process Engineering and Industrial Engineering in Toyota Production System
Jidoka, a pillar of Toyota Production Systems advocates automation with human touch in all operations of a process to increase productivity of operators as well as that of total systems.
Automation of Operations in Flow Process Chart
You need hardware for automation.
Based on Groover's Chapter on Sensors, Actuators, and Other Control System Components
CHAPTER CONTENTS
Sensors, Actuators, Analog-to-Digital Conversion, Digital-to-Analog Conversion, Input/Output Devices for Discrete Data
SENSORS
A wide variety of measuring devices is available for collecting data from the manufacturing process for use in feedback control. In general. a measuring device is composed of two components: a sensor and a transducer. The sensor detects the physical variable of interest (such as temperature. force. or pressure), The transducer converts the physical variable into an alternative form (commonly electrical voltage), quantifying the variable in the conversion.
Measuring Devices Used in Automation
Measuring Device Description
Accelerometer: It is an analog device used to measure vibration and shock. Various physical phenomena are used.
Ammeter: It is an analog device. It measures the strength of an electrical current.
Bimetallic switch: It is a switch. It uses bimetallic strip which due to a temperature change can deflect to open and close electrical contact. Bimetallic coil consists of two metal strips of different thermal expansion coefficients bonded together.
Bimetallic thermometer: It is an analog temperature measuring device. It consists of bimetallic coil that changes shape in response to temperature change. Shape change of coil can be calibrated to indicate temperature.
DC tachometer: Analog device. It consists of dc generator that produces electrical voltage proportional to rotational speed
Dynamometer: Analog device. It is used to measure force. power, or torque. Various physical phenomenon (e.g ., strain gage, piezoelectric effect) are used.
Float transducer: Float attached to lever arm. Pivoting movement of lever arm is measured first and it is used to measure liquid level in vessel (analog device) or to activate contact switch (binary device).
Fluid flow sensor: It provides analog measurement of liquid flow. It is usually based on pressure difference between flow in two pipes of different diameter.
Fluid flow switch Binary switch similar to limit switch but activated by increase in fluid pressure rather than by contacting object.
Linear variable differential transformer: Analog position sensor consisting of primary coil opposite two secondary coils separated by a magnetic core. When primary coil is energized, induced voltage in secondary coil is function of core position. Can also be adapted to measure force or pressure.
Limit switch [mechanical]: Binary contact sensor in which lever arm or pushbutton closes (or opens) an electrical contact.
Manometer: Analog device used to measure pressure of gas or liquid. Based on comparison of known and unknown pressure forces. A barometer is a specific type of manometer used to measure atmospheric pressure.
Ohmmeter Analog device that measures electrical resistance.
Optical encoder: Digital device used to measure position and/or speed, consisting of a slotted disk separating a light source from a photocell. As disc rotates, photocell senses light through slots as a series of pulses. Number and frequency of pulses are proportional (respectively) to position and speed of shaft connected to disk. Can be adapted for linear as well as rotational measurements.
Photoelectric sensor Binary noncontact sensor (switch) consisting of emitter (light source) and receiver (photocell) triggered by interruption of light beam. Two common types: (1 ~ transmitted type, in which object blocks light beam between emitter and receiver; and 12~ retrorettecttve type, in which emitter and receiver am located in one device and beam is reflected off remote reflector except when object breaks the reflected light beam.
Photoelectric sensor array Digital sensor consisting of linear series of photoelectric sensors. Array isdesigned to indicate height or size of object interrupting some but not all of the light beams.
Photometer Analog sensor that measures illumination and light intensity.
Piezoelectrictransducer Analog device based on piezoelectric effect of certain materials (e.g" quartz) In which an electrical charge is produced when the material is deformed. Charge can be measured and is proportional to deformation. Can be used to measure force, pressure,and acceleration.
Potentiometer Analog position sensor consisting of resistor and contact slider. Position of slider on resistor determines measured resistance. Available for both linear and rotational (angular) measurements.
Proximity switch: Binary noncontact sensor is triggered when nearby object induces changes in electromagnetic field. Two types: (1~ inductive and (2) capacitive.
Radiation pyrometer Analog temperature-measuring device that senses electromagnetic radiation in the visible and infrared range of spectrum.
Resistance-temperature detector Analog temperature-measuring device based on increase in electrical resistance of a metallic material as temperature is increased.
Strain gage Widely used analog sensor to measure force, torque, or pressure. Based on change in electrical resistance resulting from strain of a conducting material.
Thermistor Analog temperature-measuring device based on decrease in electrical resistance of a semiconductor material as temperature is increased.
Thermocouple: Analog temperature-measuring device based on thermoelectric affect, in which the junction of two dissimilar metal wires emits a small voltage that is a function of the temperature of the junction. Common standard thermocouples include: chromel-alumel, iron-constantan, and chrornet-constantan.
Ultrasonic range sensor Time lapse between emission and refieetton (from object) of high-frequency sound pluses is measured. Can be used to measure distance or simply to indicate presence of object
Course Notes:
http://www.just.edu.jo/~haalshraideh/Courses/IE431/Lecture_slides/ch6%20sensors_and_actuators.pdf
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