Design for EngineeringUnit 4 Instrumentation and Control SystemsAnnette BeattieJune 9, 2006

Instrumentation and Control SystemsETP 2006 – Annette BeattieThis material is based upon work supported by the National Science Foundation under Grant No. 0402616. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the view of the National Science Foundation (NSF).

Engineering

The engineering profession is based upon mathematics and data.

Design decisions and changes are ALWAYS based upon data that has been gathered.

Data is gathered through instrumentation and control systems.

Instrumentation and Control Systems

Instrumentation - the act of using instruments for a particular purpose

Ex. - instrumentation on a car dashboard - speedometer, odometer, oil gauge, temperature, etc.

(ITEA/CATTS, 2003)

Instrumentation and Control Systems

Control - to keep within limits or to have power over

System - a means of achieving a desired result. It has: Input Process Output Feedback

(ITEA/CATTS, 2003)

Instrumentation and Control Systems

System example - CarInput - driver puts it in drive, pressure on the

pedal Process - transmission is activated, gas is

sent to engineOutput - car is ready to move forward, car

moves according to pressure on pedalFeedback - PRND12 - the D is highlighted,

the speedometer gives speed read out. We also receive feedback from warning lights on the dash to tell us if something is wrong with the car or if we need fuel.

Instrumentation and Control Systems

Control system - a system for controlling the operation of another system (dictionary.net, n.d.)

Example - the dashboard in your carExample - the stereo in your car

What is the control system? What is the system it’s controlling? What is the instrumentation?

Closed-Loop Control One that involves feedback to ensure set

conditions are met (school-resources.co, n.d.)

Example - you turn on the radio, pick a station (input), listen to the song (process), you don’t care for it (feedback), and decide to change stations (output) the loop continues picking another station until

the feedback says to stay on that station. Or everyone else in the car is yelling at you, which is another kind of feedback.

Open-Loop Control

The system of commands are carried out regardless of the consequences. (school-resources.co, n.d.)

Example - Sprinklers for a golf course programmed to come on at 6:00 am even if it’s raining.

Binary The binary number system (aka base 2)

represents values using two symbols, typically 0 and 1.Computers call these bits.

A bit is either off (0) or on (1). When arranged in sets of 8 bits (or 2 bytes)

256 values can be represented (0-255). Using an ASCII chart, these values can be

mapped to characters and text can be stored.It's not magic, it's just math! (Ciske, n.d.)

Binary

Example - the word “Tech Ed” is written in binary code as: 01010100011001010110001101101000001000000100010101100100 (Ciske, n.d.)

Digital

Conversion of information into binary bits of data for transmission through wire, fiber optic cable, satellite, or over air techniques. Method allows simultaneous transmission of voice, data or video. (Remote Satellite Communications, 2006)

Examples - a computer, a digital clock

Analog Also spelled analogue, describes a device

or system that represents changing values as continuously variable physical quantities.

A typical analog device is a clock in which the hands move continuously around the face. Such a clock is capable of indicating every possible time of day. In contrast, a digital clock is capable of representing only a finite number of times (every tenth of a second, for example). (webopedia.com, n.d.)

Analog vs. DigitalIn general, humans experience the

world analogically. Vision, for example, is an analog experience because we perceive infinitely smooth gradations of shapes and colors.

Computers are digital machines because at their most basic level they can distinguish between just two values, 0 and 1, or off and on. (webopedia.com, n.d.)

Analog vs. Digital

A converter is used to change analog information into digital information that a computer can understand.

In turn, a different converter is used to convert digital information put out by a computer into analog data.

Microprocessor A microprocessor --

also known as a CPU or central processing unit -- is a complete computation engine that is fabricated on a single chip.

This is the first microprocessor ever invented - the Intel 4004. (Howstuffworks.com, n.d.)

Microprocessors The first PC

microprocessor was the Intel 8080. It had 6000 transistors.

Today’s processor for PC’s is the Pentium 4. It has 42 million transistors. (Howstuffworks.com, 2000)

Fuzzy LogicA problem-solving control system method It provides a simple way to arrive at a

definite conclusion based upon vague, ambiguous, imprecise, noisy, or missing input information.

It mimics how a person would make decisions, only much faster. (Seattle Robotics Society, n.d.)

Deals with reason that is approximate instead of precise. (wikipedia.org, n.d.)

Fuzzy Logic For example, rather than dealing with

temperature control in terms such as "SP =500F” and "T <1000F", terms like "IF (process is too cool) AND (process is getting colder) THEN (add heat to the process)" or "IF (process is too hot) AND (process is heating rapidly) THEN (cool the process quickly)" are used.

These terms are imprecise and yet very descriptive of what must actually happen. Similar to how you would think and react in the shower if the temperature changed. (Seattle Robotics Society, n.d.)

Fuzzy Logic

Fuzzy truth represents membership in vaguely defined sets, not likelihood of some event or condition. To illustrate the difference, consider this scenario: Bob is in a house with two adjacent rooms: the kitchen and the dining room. In many cases, Bob's status is "in the kitchen" which is completely plain: he's either "in the kitchen" or "not in the kitchen". (wikipedia.org, n.d.)

Fuzzy Logic What about when Bob stands in the

doorway? He may be considered "partially in the kitchen". Quantifying this partial state yields a fuzzy set membership. With only his little toe in the dining room, we might say Bob is 99% "in the kitchen" and 1% "in the dining room", for instance. No event (like a coin toss) will resolve Bob to being completely "in the kitchen" or "not in the kitchen", as long as he's standing in that doorway. Reasoning that is approximate rather than precisely deduced. (wikipedia.org, n.d.)

Fuzzy Logic Fuzzy logic allows for values between and

including 0 and 1, shades of gray as well as black and white.

Fuzzy logic is used in air conditioners, dishwashers, elevators, video games, etc.

It was also used to create MASSIVE (Multiple Agent Simulation System in Virtual Environment). It is computer animation and artificial intelligence software that was developed for the Lord of the Rings trilogy. (wikipedia.org, n.d.)

Fuzzy Logic Fuzzy logic

software was used to create award winning visual affects, particularly the battle scenes of Lord of the Rings.

The software was also used in The Lion, the Witch, and the Wardrobe. (wikipedia.org, n.d.)

Neural Systems A type of artificial intelligence that attempts

to imitate how a human brain works. Rather than using a digital model, in which

all computations manipulate 0’s and 1’s, a neural network works by creating connections between processing elements, as if computer neurons.

The organization and weights of the connections determine the output. (Pcwebopidia.com, n.d.)

Neural SystemsNeural network systems are

particularly effective for predicting events when the networks have a large database of prior examples to draw on.

Strictly speaking, a neural network system implies a non-digital computer, but neural network systems can be simulated on digital computers. (Pcwebopidia.com, n.d.)

Neural Systems Neural networks

are currently used prominently in voice recognition systems, image recognition systems, industrial robotics, medical imaging, and aerospace applications. (Pcwebopidia.com, n.d.)

Sensors

A device that responds to a stimulus, such as heat, light, or pressure, and generates a signal that can be measured or interpreted. (St. Jude, 2006)

A significant change involves an exchange of energy, so sensors can be classified according to the type of energy transfer they detect. (Wikipedia.org, n.d.)

Sensor Examples

Thermal sensors Thermometers, thermostats,

thermocouplesElectromagnetic sensors

Ohmmeter, voltmeter, metal detectorsMechanical sensors

Altimeter, pressure gaugeMotion sensors

Radar gun, speedometer, odometer (Wikipedia.org, n.d.)

ActuatorA mechanism that puts something into

automatic action.Examples -

A mail delivery system that delivers email into the user’s mailbox

A human - moving arms, legs, fingers A robot - that grasps parts and moves

them Motors - used when circular motions are

needed or a rack and pinion is used in conjunction to make a linear motion (Howstuffworks.com, 2000)

Actuator example A model of an

actuator (IX SCARA Applications, n.d.)

http://www.intelligentactuator.com/media/m-ap-ix-0001_01.swf

Actuator example Actuator used to open power door locks The hook at the end of the actuator rod

moves up or down which mimics a person moving the knob up or down. (Howstuffworks.com, 2000)

Actuator example Inside of the actuator The small electric motor turns the gears

which move the rack and pinion which moves the actuator rod up or down. (Howstuffworks.com, 2000)

Stepper Motor These are small electric

motors that can spin quite quickly and can be started and stopped “on a dime”. Instead of moving continuously, they move is small, precise increments.

Stepper motors are used to spin floppy disks.

They are also used to move an ink jet printer head assembly back and forth. (Howstuffworks.com, 2000)

Synchro Motor

A system consisting of a generator and a motor so connected that the motor will assume the same relative position as the generator; the generator and the motor are synchronized (Thefreedictionary.com, n.d.)

A synchro motor resembles a small electric motor in size and appearance and operates like a variable transformer.

Synchro Motor Synchros are used

primarily for the rapid and accurate transmission of data.

They are used to move small dials to give read-outs. (Concord University, n.d.)

Putting it all together

Most manufactured cars today have around 50 microprocessors.

The following is a picture of the most important computer in a car which uses many microprocessors - the engine control unit (ECU). (Howstuffworks.com, 2000)

Putting it all together

Putting it all together It gathers data from many different sensors It uses closed-loop control to monitor the

outputs of a system to control the new inputs of that system.

It knows everything about: Coolant temperature Amount of oxygen in the exhaust, etc.

With this information it performs millions of calculations each second.

This determines the best spark timing and how long the fuel injector is open, for instance. (Howstuffworks.com, 2000)

Putting it all together The pins on this ECU’s connector interface

with sensors and control systems all over the car. (Howstuffworks.com, 2000)

Other components in the ECU are:

An analog-to-digital converter is used to read the outputs of some of the sensors in the car, such as the oxygen sensor. The output of an oxygen sensor is an analog voltage, usually between 0 and 1.1 volts (V). The processor only understands digital numbers, so the analog-to-digital converter changes this voltage into a 10-bit digital number. (Howstuffworks.com, 2000)

Other components in the ECU are:

Digital-to-analog converters - Sometimes the ECU has to provide an analog voltage output to drive some engine components. Since the processor on the ECU is a digital device( a computer), it needs a component that can convert the digital number into an analog voltage. (Howstuffworks.com, 2000)

Sources Ciske. (n.d.). Retrieved June 9, 2006 from the website: Nickciske.com Concord University (n.d.). Retrieved June 9, 2006 from the website:

students.concord. edu Dictionary.net. (n.d.). Retrieved June 9, 2006 from the website:

http://www.dictionary.net/control+system Howstuffworks.com. (2000). Retrieved June 9, 2006 from the website:

Howstuffworks.com ITEA/CATTS. (2003). Introduction to engineering: units of instruction. Retrieved

June 9, 2006 from the website: http://www.vcsu.edu IX SCARA Applications. (n.d.). Retrieved June 9, 2006 from the website:

intelligentactuator.com Pcwebopidia.com. (n.d.). Retrieved June 9, 2006 from the website:

Pcwebopidia.com Remote Satellite Communications. (2006). Retrieved June 9, 2006 from the

website: Spidersat.net School-resources. (n.d.). Retrieved June 9, 2006 from the website: school-

resources.co Seattle Robotics Society. (n.d.). Retrieved June 9, 2006 from the website:

seattlerobotics.org St. Jude. (2006). Retrieved June 9, 2006 from the website: stjude.org Webopedia.com. (n.d.). Retrieved June 9, 2006 from the website: webopedia.com Wikipedia.org, (n.d.). Retrieved June 9, 2006 from the website: Wikipedia.org

Standards

Standard #2: Students will develop an understanding of the core concepts of technology [2.Y] The stability of a technological

system is influenced by all of the components in the system, especially those in the feedback loop.

[2.FF] Complex systems have many layers of controls and feedback loops to provide information.

Standards Standard #17: Students will develop an

understanding of and be able to select and use information and communication technologies. [17.M] Information and communication systems

allow information to be transferred from human to human, human to machine, machine to human, and machine to machine.

[17.Q] Technological knowledge and processes are communicated using symbols, measurement, conventions, icons, graphic images, and languages that incorporate a variety of visual, auditory, and tactile stimuli.