10/21/2015SME3252: Mechatronics Lecture 2 1 Introduction to Mechatronics (cont.) Lecture 2

04/20/23 SME3252: Mechatronics Lecture 2

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Introduction to Mechatronics

(cont.)

Lecture 2

1.5.5: Sequential controllers

• Situation – switched on and off at particular preset times

• After Step 1 completes, Step 2 starts. After Step 2 completes, starts Step 3, etc.

• Sequential control – when control is done in such that actions are ordered in a time- or event-driven sequence

• By electric circuit with sets of relays or cam-operated switches

• Now – hard-wires circuit is replaced with microprocessor control


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• As an illustration – domestic washing machine

• Operations must be in correct sequence:

1.Pre-wash cycle

2.Main wash cycle

3.Rinse cycle

4.Spin cycle

• Discuss in class for each cycle


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Examples of mechatronics systems

• Domestic appliances – fridge, freezers, microwave ovens, washing machines, vacuum cleaners, digital cameras, videos, DVD player, camcorder, etc.


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iRobot® Roomba® Scheduler Vacuuming Robot

Our top-of-the-line vacuuming robot features a built-in scheduling system that adds ultimate convenience. Program up to seven cleaning times to clean automatically as often as you like--even when you're out. Includes filters, brushes, Cleaning Tool and 2 Scheduling Virtual Walls.


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iRobot® Scooba™ Floor Washing Robot

The first floor washing robot for the home that preps, washes, scrubs and dries your floor. Uses fresh Clorox® Scooba™ cleaning solution from start to finish, leaving floors clean, dry and ready to walk on. Safe to use on all sealed hardwood, tile and linoleum flooring.


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• Domestic systems – air conditioning units, security systems, automatic gate control


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Hand recognition

Finger print

Iris recognition

DNA

Signature

Voice recognition

Keystroke recognition Face recognition

SECURITY SYSTEM


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• Office equipment – laser printers, liquid crystal display (LCD), scanners, photocopier, fax machines, computer peripherals


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• Retail equipment – automatic labeling system, bar coding machines,


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• Banking system – cash registers, automatic teller machine


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• Manufacturing equipment – NC tools, pick-and-place robot, AGV, robotic systems


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• Aviation system – cockpit controls and instrumentation, landing gear systems

• Latest – unguided aerial vehicle (UAV) with micro turbine


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Airbus 380- Europe

Size 800 passengers double

Boeing 787 Dreamliner- USA

25% fuel saving


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• Automotive:• - braking system, ABS• - security system, door lock• - driverless• -


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• Military – bomb disposal unit, surveillance system, vehicle

• Hospital facilities for casualties


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• Agriculture • – wireless monitoring system• - precision agriculture


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Benefits (1)

• More featuresA mechanical design - only one

functionE.g. using PIC microcontroller -

expanded features and functionalityFlexibility of adding features - LCD

displays, LEDs, motors,


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Benefits (2)

• More user friendlyFurther improvement leads more

user-friendly productE.g. in automotive system - power

windows, power door locks, keyless entry, and numerous other conveniences


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Mercedes S-Class


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Benefits (3)• Precision controlPurely mechanical solutions are not as

efficientCruise control in an automobile - allows for

precise controlA microcontroller based - controls many

different variables (i.e. velocity, acceleration, cumulative changes in velocity) to give the car a smooth acceleration to the desired speed as well as maintaining a constant velocity over varying load conditions.


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Benefits (4)

• More efficientMore efficiency by adding intelligence to

the designMicrocontroller can make better use of the

energy available by offering the precision control

Pulse Width Modulation (PWM) can be used instead of resistive elements to vary the voltage and current to a load, thereby increasing the efficiency of the system.


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Benefits (5)

• Lower cost In some cases, a mechatronics system

costs less than the alternative mechanical solution

A complex mechanical solution is simplified using a microcontroller-based approach

Design time, product size, and reliability can all be improved

These factors impact the cost over the lifetime of a product.


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Benefits (6)

• Flexible designThe specifications of a product can change

during the course of its designAny software controlled parameters can be

changed quickly without the need for a product redesign

This flexibility also allows the same hardware to be used in different products

The software is simply changed to meet the needs of each product.


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Benefits (7)

• Increased reliabilityMechanical designs - prone to wear and

tear over time e.g. mechanical odometer in car

Consists of a flexible cable running from the transmission to the odometer gage – unreliable, prone to failure

Mechatronic design - an optical encoder and digital display, which increases system reliability.


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Old mechanical odometer


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Benefits (8)

• Smaller size• Motor drive circuits - over-sized drive

stages to handle in-rush current• Can be reduced by implementing soft-

startup using a microcontroller.


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Blackberry PDA phone

iphone by Apple

http://images.google.com.my/imgres?imgurl=http://techdigest.tv/apple-iphone-in-hand-thumb.jpg&imgrefurl=http://www.techdigest.tv/2007/01/apple_iphone_th_1.html&usg=__h0qJTeKspYIhMcIQmmvcBVcal2k=&h=509&w=449&sz=54&hl=en&start=2&tbnid=Wqd6YEDTsLnRrM:&tbnh=131&tbnw=116&prev=/images%3Fq%3Diphone%26as_st%3Dy%26gbv%3D2%26hl%3Den


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Benefits (9)

• Safer• Adding intelligence - system is safe• E.g. Automatic shutdown to a coffee pot or

sense when a system is overheating• Safety checks added to a system with

microcontroller controlling the system.


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Automatic shut off coffee pot


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Exercises• Definition of “Mechatronics System”• Examples of applications• Benefits and comparisons of

mechatronic system with mechanical system or electromechanical system by giving a practical example

• What is sequential controller and give examples

• Explain sequential control in a dishwater


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End of Lecture 2

Documents

10/21/2015SME3252: Mechatronics Lecture 2 1 Introduction to Mechatronics (cont.) Lecture 2