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Design and Applied Technology (Secondary 4

1. Figure 3 13 13 Fail safe Design Fail safe design is an important part in PLC controlled systems The effect of failed open wiring on the device being controlled is brought to an attention In this motor control circuit the problem is if the input wiring for the contact X2 the stop switch was fail open there would be no way to stop the motor The solution to this problem can be a reversal of logic between the X2 contact inside the PLC program and the actual Stop push button switch Design and Applied Technology Secondary 4 6 L1 L2 Motor M1 start e A a Motor contactor Motor stop released Figure 3 14 When the normally closed Stop push button is unactuated not pressed the PLC s X2 input will be energized thus closing the X2 contact inside the program This allows the motor to be started when input X1 is again energized and continue to run even the Start pushbutton is no longer pressed When the Stop pushbutton is actuated the input coil X2 will de energize thus opening the X2 contact inside the PLC program and shutting off the motor 14 Function of Control Relays In addition to input X and output Y program elements PLCs provide internal coils and contacts with no intrinsic connection to the outside world These are used much the same as control r
2. Figure 3 10 11 Latching function in PLC When releasing the Start pushbutton the normally open X1 contact will return to its open state electrical non conducting and the motor will continue to run It is because the Y1 detent contact continues to provide a path to power the coil X1 and Y1 thus keeping the Y1 output energized Design and Applied Technology Secondary 4 6 eee ee L1 L2 M1 C Motor contactor energized a Figure 3 11 12 Stopping the motor To stop the motor press the Stop pushbutton this will energize the X2 input and open the normally closed contact breaking continuity to the Y1 coil Design and Applied Technology Secondary 4 6 L1 L2 M1 2 Motor contactor stop actuated X1 X2 Y1 Figure 3 12 When the Stop push button is released input X2 will be de energized returning contact X2 to its normal closed state The motor however will not start again until the Start pushbutton X1 is actuated It is because the detent of Y1 has been de energized and returns to normal open Design and Applied Technology Secondary 4 6 Ll L2 1 Motor i start 1 eee N z Motor Motor contactor stop released
3. Ll L2 mie VV e PA Personal pan Programming computer C cable display Figure 3 4 5 Inactivating a push button When the pushbutton switch is unactuated unpressed no power is sent to the X1 input of the PLC According to the program which shows a normally open X1 contact in series with a Y1 coil no power will be sent to the Y1 coil Thus the PLC s Y1 output remains de energized The indicator lamp remains dark Design and Applied Technology Secondary 4 6 6 Activating a push button If the pushbutton switch is pressed power will be sent to the PLC s input X1 The contact X1 in the program will assume the actuated non normal state It is a relay contact actuated by energizing the relay coil named X1 In this case energizing the input X1 will cause the normally open contact X1 to close sending power to the coil Y1 When the coil Y1 of the program energizes the real output Y1 will become energized lighting up the lamp that is connected to it L1 L2 switch actuated x g RK lamp lights Lf _ Personal Y1 Programming computer cable display contact and coil symbols turn color indicating power conducted through circuit Figure 3 5 7 Role of Personal Computer The personal computer is used to display and edit the PLC s program There is no need of PLC for the con
4. No Topic Hrs Type of delivery Remarks T C 1 Topic 3 1 What is Programmable 1 0 RM in classroom logic controller PLC 2 Topic 3 2 Programming the PLC 2 0 RM in classroom 3 Topic 3 3 Application of ladder 3 0 RM in classroom Logic Diagram 4 Topic 3 4 Programmable Interface 3 0 RM HO in Controller special room 5 Topic 3 5 Stepper Motor and 1 0 RM in classroom Servomotor 6 TLT 2 Hands on Activity 0 3 RM HO DM in Graded assignment Controlling an automated traffic special room lights using programmable logic controller 7 Quizzes 0 4 RM HO DM in Graded assignment Assessment Tasks 8 10 special room Electro pneumatic PLC Total Hours 10 9 Table 5 Detailed Plan for delivery of Chapter 3 Chapter 4 Robotics No Topic Hrs Type of delivery Remarks T C 1 Topic 4 1 Definition of Robots 1 0 RM in classroom 2 Topic 4 2 Mechanical structure of 1 0 RM in classroom Industrial Robotic Arms 3 Topic 4 3 Robot Anatomy 1 0 RM in classroom 4 Topic 4 4 Robot Control Systems 1 0 RM in classroom 5 Topic 4 5 Application of Robots 1 0 RM in classroom 6 Quizzes 0 13 RM HO DM in Graded assignment Theme based learning Task 3 special room Design and Make Project Pipe Cleaning Inspection Robot Theme based learning Task 4 Mars Exploration Design an innovative End effector for Mars Lander Total Hours 5 14 Table 6 Detailed Plan for delivery of Chapter 4 E
5. Design and Applied Technology Secondary 4 6 Legends T Teaching DM Demonstration C Coursework HO Hands on Activity Q Quiz CS Case Study TLT Theme based Learning Task EX Exercises Practical Task RM Resource Materials DP Design Project Design and Applied Technology Secondary 4 6 SECTION 5 SAMPLE LESSON PLANS TEACHING SCHEME SAMPLE 1 Design and make Project 1 Pipe Cleaning Robot or 2 Pipe Inspection Robot Aims and Objectives Students will become an expert in design and development process micro controller application interfacing techniques and mechanical design through this design project Students can also gain other learning experiences and develop generic skills by the end of this learning task Learning Task Planning Philosophy 1 Adopt Life Wide Learning LWL approach to provide students with real life scenario and authentic learning experience in developing their dedicated robots 2 Students can develop their dedicated robots by system integration approach and based on the school resources It eliminates the chance of failing the project for the low achieving students 3 Adopt the Design project approach and promote collaborative learning throughout the whole robot development process Teaching Strategies 1 Teacher plays the role as a consultant facilitator information and resources provider throughout the teaching and learning process 2 Teacher is responsible for the proje
6. 1 Students should carry out group discussion to clarify and consolidate the concepts taught in this chapter It is important to have clear concepts before proceeding further to the subsequent chapters 2 Students should take the Stop and Think and the assessment activities to gain some hands on activities in studying the control systems Period Allocation No of 6 periods No of Periods 2 double Teacher to 1 40 periods per cycle periods students ratio No of 8 hours Duration of 80 mins Place Classroom hours each period Level NSS 2 Theme Basics of Topics Control Theory Control Systems Design and Applied Technology Secondary 4 6 TEACHING SCHEME Period Teaching Activities Learning Activities Teaching and Resources learning Assessment Competency Level Lecture and Demonstration Worksheet Daily examples found in the Students can clearly define the 1 Explain the concepts of open loop Q amp A campus such as concepts and closed loop control systems Small group air conditioner Students give examples to Topic 1 1 discussion can dispenser these concepts 2 Explain the concepts of system and Homework Study of a washing machine Complete the assessment task 01 subsystem Topic 1 2 in Technology and Living Question 1 3 Explain the concepts of DSP as room or supplementary notes optional A video clip showing a 4 Expl
7. Video taking of process Students can write 1 Students assemble the 1 Test their robots in the test rig Networked PC with group blog in school application device onto the 2 Prepare their final presentation Bloggers in school intranet for sharing 10 mobile platform and perform the Intranet final testing 2 Students fine tune their robots E Design and Applied Technology Secondary 4 6 Teaching and learning Assessment Resources Competency Level Teaching Activities Learning Activities 3 Teacher assesses the robots performance and provide feedback Final Presentation and Open Students should Video recorder Submit all Competition 1 Prepare a 15 20 minutes presentation by Networked computer presentation 1 Teacher arranges an open event webpage blog or Powerpoint Wireless microphone materials 11 and invites principal teachers demonstration Assessment and Scores Teachers assess and parents and students to form the 2 Conduct rehearsal before final presentation sheets for judge panel evaluate final judge panel to assess group submission presentation and demonstration Exhibition Students should Networked computer Complete a 1 Teacher organizes a 1 Form an editorial committee for publishing Video recorder reflection journal 12 mini exhibition in school the exhibition brochure Bench and booths Prepare and publish campus and asks students to be 2 Form an organizing committe
8. A flow control valve is fitted at the outlet of the single acting cylinder to slow down the retracting action of the single acting cylinder In practice the delay time needs to be adjusted and tested by trial and error Design and Applied Technology Secondary 4 6 Suggested solution to Question 7 When the push button is pressed the double acting cylinder will extend and hold the position until another push button is pressed to make it retract It is because the conveyor needs to be held in the last moved position and only the double acting cylinder can meet this requirement Ajk lL Suggested solution to Question 8 Electro pneumatic START ZZ 4mins LAMP Rung 1 Timers 1 and 2 are set on when the timer 3 is being off and the interrupt button is triggered Rung 2 Motor 1 runs as long as the timer 1 is off after 4 minutes timer 1 turns on but motor 1 stops Design and Applied Technology Secondary 4 6 Rung 3 Motor 2 runs as long as timer 2 is off After 6 minutes the timer 2 becomes on and motor 2 stops Rung 4 The lamp is on only if timer 2 is on and timer 3 is off The lamp turns on as soon as motor 2 stops The lamp will turn off when timer 3 turns on after 90 seconds Interrupt Suggested solution to Question 9 Programmable Logic Controller Start COUNTER CYLINDER Rung 1 The counter will be decremented by 1 whenever the photo sensor is inte
9. Students should Video signal transfer kits Complete a reflection transmission and interfacing with 1 Understand the theory of signal transfer for demonstration journal computer 2 Apply the signal transfer technologies to their Self directed 1 Teacher demonstrates the wired designed robots readings of data ve and wireless transmission of sheets websites video signal to the computer reference materials 2 Teacher explains the basic principle of signal transfer Demonstration of Interfacing Students should Demonstration kits of Complete a reflection Sensors 1 Understand the interfacing photo resistors journal 1 Teacher uses teaching kits to 2 Transfer the sensors interfacing technologies near infrared proximity Self directed demonstrate the interfacing of to their designed robots sensors micro switches readings of data different sensors that include mercury tilt sensors and sheets websites 07 photo resistors near infrared sonar transducers reference materials proximity sensors micro switches mercury tilt sensors and sonar transducers Teacher explains the basic principles of different sensors Design and Applied Technology Secondary 4 6 Teaching and learning Assessment Teaching Activities Learning Activities Resources Competency Level Making of Mobile Platform Students should Basic workshop tools Submit paper 1 Teacher demonstrates the 1 Use
10. 4 Pneumatic Circuitry Chapter 2 Pneumatics OOE 1 2 Module 4 nee System 2 5 Electro pneumatic and Sub system Module 1 Systems 2 1System Electronics Automation Modules f i 1 4 Logic Circuits i Module 4 1 5 Control of fluid level in a tank Chapter 3 Programmable control systems 3 1 Whatis Programmable logic controller PLC i Module 4 H i 2 4 Memory and Counter Chapter 4 4 1 Robotics Definition a 3 2 Programming iad 3 4 Programmable the PLC ss nn Interface fF i Module 3 H Controller i 3 2 Basic concepts i ofCiMandFMS Structure of aaa Industrial Robotic Arms Module 3 ji Module 4 i 2 3 Latch Circuit 4 2 Mechanical H at Tresc 4 4 Robot Control Sane q p eae Systems 3 5 Stepper Ladder Logic Diagram Motor and 4 3 Servomotor POROLAOMIOMY 4 5 Applications TA of Robots 3 gio cosbuer Basi 3 1 Computer Numerical Control and CAM Design and Applied Technology Secondary 4 6 SECTION 3 KEY CONCEPTS CHAPTER1 BASIC OF CONTROL SYSTEM The key concepts of this chapter employ daily household electrical appliances as examples for learning fundamental control theory such as the temperature control in oven the fluid level control in water tank the temperature and humidity control in air conditioner the traffic control in traffic light and the sequential logic control in washing mach
11. Topic 3 3 and circuit Lecture 1 Q amp A Real motors and control circuits for Students can describe the 1 Explanation of stepping motors theory and 2 Demo board explanation working principle 04 H bridge control of DC motors Topic 3 5 Theme based Learning Task 2 1 Hands on PLC kits should be available for Students can complete the Hands on activity Controlling an automated activities hands on practice design on their own 05 06 ier traffic lights using PLC Assessment Tasks 1 Hands on PLC kits should be available for Students can complete the 07 08 1 Question 8 10 Programmable Logic activities hands on practice design on their own Controller E Design and Applied Technology Secondary 4 6 SECTION 6 TEACHING NOTES Chapters refer to the chapters in the Learning Resource Materials of this Module Introduction This module aims at providing students with broader sense of integrated knowledge to understand automated control systems This module is composed of four chapters that include the concepts of Control System Basics the know how of Pneumatics cum Electro pneumatics the application of Programmable Control Systems and Robotics The resources packages consist of student s notes STOP and THINK exercise examples quizzes four thematic learning tasks and assessments The students notes provide the theoretical background for the concept building whilst the four thematic learni
12. a more stable controlled condition 3 Give one daily example on Open Loop control system and Closed Loop control system Draw the block diagrams for the examples Washing machine is a daily example of open Loop control Though nowadays the washing machines have many programmed washing cycle according to the nature of fabrics weight of laundry and the level of cleanliness and after the cleaning cycle there is no guarantee of the laundry has been cleaned properly or not Human intervention is needed The laundry needs to be checked by visual inspection If it is not cleaned thoroughly the laundry needs to be washed again Obviously the block diagram below is a simplified situation The washing machine also has a closed Loop control sub system inside such as the water temperature control system and the water level detection system Control value Controlled value time sequence Controller AC Motor washing cycle Timer Laundry drum An electric kettle is an example of closed Loop control system When it is set to 98 C the heating element is switched on to boil the water Once the temperature is reached the heating element will be switched off The temperature is continuously monitored to provide a feedback signal to the controller Once the measured temperature drops below the desired temperature the heating element will be switched again to increase the temperature to the desired value Design and Applied Technology Secondary 4
13. altered system in the state that the pushbutton is not actuated not being pressed L1 L2 mA lamp lights Personal x1 pany E computer cable display colored components show power conducted through the circuit with contact X1 in its normal status Figure 3 6 Design and Applied Technology Secondary 4 6 Ll L2 switch actuated A lamp is dark Personal X1 Y1 Programming computer man cable display un colored components show no continuity in the circuit Figure 3 7 One of the advantages of implementing logical control in software rather than in hardware is that input signals can be re wired virtually in the program as many times as necessary Take the following circuit and program as example changing the input signal condition of the circuit to energize the lamp when at least two of the three pushbutton switches are simultaneously actuated Design and Applied Technology Secondary 4 6 L1 L2 T aS AA X1 X2 Y1 X2 X3 X1 X3 Figure 3 8 9 Flexibility of using virtual contacts Using a PLC to program as many contacts as needed for each X input Each input and output is just a single bit in the PLC s digital memory either 0 or 1 and can be recall
14. daily example such as an electric toothbrush that is composed of a power and charging sub system cleaning sub system drive sub system and the control sub system The cleaning sub system can be as simple as the mechanism of changing the brush head the drive sub system can be as simple as a DC motor whilst the control sub system may be just a push button Design and Applied Technology Secondary 4 6 How do Temperature Controllers work The example of air conditioner is only a simplified system used to illustrate the concept of temperature control However in practice the situation is a bit more complicated Here is an example of industrial application A temperature control system relies upon a controller which accepts a temperature sensor such as a thermocouple or RTD as input It compares the actual temperature to the desired control temperature or setpoint and provides an output to a control element The controller is one part of the entire control system and the whole system should be analyzed in selecting the proper controller The following items should be considered when selecting a controller Type of input sensor such as thermocouple RTD and temperature range Type of output required electromechanical relay SSR analog output Control algorithm needed on off proportional PID Number and type of outputs heat cool alarm limit Po tS There are three basic types of controllers on off proportional and PID On Of
15. innovation we require our students to think of other ways or alternative to complete the task B The innovative design can be assessed and measured against the traditional design to see how fast and how good the innovative design can be If not why should I need to be innovative What are the points for this Bear in mind to make allowance for the user training and practice to any innovative design SUGGESTED ASSESSMENT SHEET Objective Innovative Student Name Class design of End effector Peer Assessor Date Assessment Criteria Self Peer Teacher 1 Innovativeness design O 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 2 Efficiency function O 1 2 3 4 57 0 1 2 3 4 57 0 1 2 3 4 5 3 Effectiveness function O 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 4 Production Technique O 1 2 3 4 57 0 1 2 3 4 5 0 1 2 3 4 5 5 Choice of materials O 1 2 3 4 57 0 1 2 3 4 570 1 2 3 4 5 6 Demo and Presentation 0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 Teacher remarks Design and Applied Technology Secondary 4 6 SECTION 8 TEACHERS NOTES FOR ASSESSMENT TASKS Suggested Solution To Question 1 A Complete the Record Form and study the sequential operations of the washing cycle Students are expected to conduct a simple study of the washing machine at home The washing cycle may not be short so students
16. likes a water curtain around the area of fire happening Its function can cool down the ambient temperature and extinguish the fire within the protected area 1 Follow up Activities Form groups and carry out a field study of fire safety measures taken in the school premises Appraise the level of automation for this fire safety measure Most often the fire safety measure in school belongs to low level as the premise is open design and does not like an enclosed commercial building Usually extinguishers fire sand fire blanket escape signage and fire hose can be seen in a school campus For a laboratory there must be two entrances for fire escape and has a pair of smoke prevention doors Also other groups of students can take a look at the shopping mall nearby Study what fire safety devices and systems are being adopted A comparison can be made with those used in the school campus A brief verbal report to state the differences and give appropriate reasons Usually for an enclosed commercial building and a shopping mall the fire safety measure level will be stringent It is assumed that the patrons are not familiar with the area In addition to the fire safety measure that can be found in school there are usually sprinkler system smoke detectors PA systems and pump room Also for a more stringent requirement all the electric cables used must be the LSOF type means low smoke and halogen free to avoid heavy smoke and poisonous gases
17. need to be patient and try to be accurate in recording the sequence and the timing B Draw a flow chart block diagram to present the sequence of the washing cycle Students need to observe the operation of washing machine Take a typical case as an example the common sequences are as follows Door closed YES or NO Water in YES or NO If Yes washing cycle starts Temperature reached if any YES or NO If NO heating element turns on Water drained YES or NO C Draw a timing diagram to represent the washing cycle The Y axis represents the rotating speed The positive and negative axis represent the drum rotating clockwise and anti clockwise respectively The amplitude represents how fast the drum rotates The X axis is the time period and represents the sequence Students need to observe the cycle of washing machine and record the time for the drum operation The time phase diagram in the resources package can be used as an example D List any state variables for the washing cycle Water level Temperature level Time for rotating drum Direction of rotating drum Suggested Solution To Question 2 For simplicity a single acting cylinder can fulfil the requirement In practice the engineer needs to designing the timing force and the design of pushing head A push actuated is used to trigger the 3 2 directional control valve If flow amplification is needed for more power rating operation anot
18. network synd 200 3 08 05 closed_loop html Closed loop control Delphion Integrated View http www delphion com details pn10 US0326454 4 Washing machine patent article LG Washing Machine User Manual http www lgwasherdryer com pdf 3431_manual pdf LG Washing Machine User Manual Fuzzynet Online http www aptronix com fuzzynet applnote air htm Air Conditioning Temperature Control Application Note Control Weekly Review _ http controlsweekly com pneumatics htm Tool Pneumatics KINEQUIP INC http www kinequip com basic_advantages asp Basic advantage of Pneumatics Fluid Power Education Foundation http www clippard com downloads general PDF Documents Intro_to_Pneumatics pdf Introduction to pneumatics and Pneumatics Circuit problem for FPEF tainer 101 Basic Series Electrical http www eatonelectrical com html 101basics Mo dules Module24 pdf Module 24 Programmable Logic Controller Introduction to PLC programming and implementation from Relay logic to PLC logic http www idc online com technical_references pdf s instrumentation Intro_to_PLC_20Pro pdf Pneumatic Application and Reference Handbook http www allair com pdf mead_pneumatic_handb ook pdf Loop Technology UK http www looptechnology com index asp Industrial Automation Technology Machine Vision System Design and Applied Tech
19. robotic basics and their applications The classification of robots the drive systems control systems and the end effectors designs are the topics to be addressed After taking this chapter students are expected to appraise a robotic system Besides the classroom teaching it is highly recommended to arrange a field trip to local industry or tertiary education laboratory to let students have a look at an industrial robotic arm B Design and Applied Technology Secondary 4 6 SECTION 4 TEACHING SCHEMES OVERALL ARRANGEMENT A total of 70 hours are allocated to cover this module Out of these 70 hours and 35 hours are recommended for coursework Teachers can fully utilize the schedule for coursework to conduct learning activities such as cross curricular or integrated design project s An estimation of number of hours required for each chapter in this module is as follows 1 Term 2 Term S4 Compulsory Core Module Chapter 1 Basics of Control System Chapter 2 Pneumatics Topic 1 1 Open Loop Closed Loop and Sequential Topic 2 1 Pressure control systems Topic 2 2 Pneumatics Components and Symbols Topic 1 2 System and Sub systems Topic 2 3 Understanding Pneumatic Components Topic 1 3 Operation of washing machine Topic 2 4 Pneumatic Circuitry Topic 1 4 Operation of traffic lights Topic 2 5 Electro pneumatic Systems Topic 1 5 Control of fluid level in a tank Assessment Tasks Question 2 7 Pneumatics 55 Topic 1 6 Ap
20. size of workpiece to be processed is limited by the size of the gantry The larger the workpiece the larger the robot 2 What are the differences of DOM and DOF DOM is the Degree of Mobility and is defined as the number of link joint pair in a robot DOF is the Degree of Freedom and is defined as the number of orientations that a robot can make 3 List the five types of joints used in robots 5 joints types can be labelled with L O R T and V for the linear orthogonal rotational twisting and revolving joints respectively 4 Suggest any specific applications of electric pneumatics and hydraulic drive systems of robots State your reasons Electric drive system can be used for pick and place of material transfer in production line as the action is simple and quick Pneumatics drive system can be used for surgery robot as clean and electrostatic free environment is required Hydraulic drive system can be used for articulated robot in automobile industry as the loading requirement is very high 5 What are regarded as Intelligent Robot Robots can have advanced sensory systems such as vision sensors and face recognition technology that process information and function like a human brain Artificial Intelligence AI allows a robot to perceive conditions and make decision based on the perceived condition An intelligent robot can make decisions when things go wrong during the work cycle communicate with human beings and make computat
21. symbols for explanation Students can understand 1 Explanation of solenoid valves and 2 Demo board Authentic demonstration if the operation of solenoid Electro pneumatics 3 Classroom Pneumatics kit available valve discussion 08 09 Lecture 1 Introduce 3 cases of industrial applications Topic 2 5 1 Classroom discussion Magnetic symbols for explanation Field trip to local industry or tertiary laboratory can be arranged Students can understand the industrial application of Pneumatics and Electro pneumatics Design and Applied Technology Secondary 4 6 MODULE 1 AUTOMATION TEACHING SCHEME SAMPLE 4 Chapters 3 Programmable Control Systems Aims and Objectives Students should gain fundamental knowledge of Programmable Control System in this chapter Students should acquire the concepts and working principle of Programmable Logic Controller Ladder logics and motor control systems are also introduced in this chapter Students should have some practical activities of tackling control design problems after completion of this chapter Teaching Strategies 1 Teacher plays the role as an instructor if there are PLC kits available for practical activities 2 Teacher can provide some worksheets to assess students understanding of ladder logic and PLC programming Learning Strategies 1 Small group discussion quiz and verbal presentation will be very effective ways of collaborative lea
22. 6 Control value Preset temperature Controlled value temperature Controller Heating Coil Temperature Sensor 4 Suggest and name the types of sensors used in a washing machine Tachometer is used to measure the speed of the laundry drum limit switch can be used to detect the closure of door Thermocouples or Thermistors can be used to measure the water temperature Thermocouple is a temperature transducer in which two dissimilar metals are connected together as a hot junction to measure the temperature Their electrical properties change and generate an open circuit voltage in related to the temperature difference The thermistor is a resistance thermometer and its resistance changes as a function of time Water level sensor with two measuring probes can be used to detect the water level and control the water inlet and drainage 5 What is the meaning of setpoint The setpoint is the desired controlled value that the controlled element need to be maintained during the control process such as the preset temperature in oven or refrigerator or the water level in water storage tank 6 What is the meaning of proportional band Mathematically the controlled value output is proportional to the error or a change in measurement by feedback device divided by the Proportional Band Controlled value Error 100 Proportional band Physically the proportional band is a range of output value which varies in proportion
23. CAD to prepare paper template with machinery and template prepared by techniques of marking out and markings that indicate all cuts holes and equipment CAD fabrication of sheet metal and bends to be made Computer with 2D or 3D Complete a reflection 08 acrylics 2 Be able to use marking out tools and CAD program journal 2 Teacher encourages students to techniques Wheels tank drive belts perform testing 3 Be able to use basic hand tools and sheet spokes shafts rollers 3 Teacher allows students evaluate metalworking techniques and bearings and redesign their idea Making of Application Devices Students should Provide electronic and Build a workable Prototypes Pipe Cleaning or Pipe 1 Apply their knowledge to build their electrical components application devices Inspection Device application devices to meet the designated such as motor control prototype 1 Students use exploratory purpose boards DC and servo Prepare a Bill of approach to build their 2 Decide what sensors to be included in their motors battery supplies Materials BOM n application devices application devices DC supplies gearboxes Complete a 2 Teacher provides consultation to 3 Prepare a Bill of Materials BOM electric wires signaling reflection journal students 4 Conduct Functionality Test and record the wires and soldering kits results Provide basic workshop consumables tools machineries and equipment Final Assembly Students should
24. Design and Applied Technology Secondary 4 6 4 a A Automation Design and Applied Technology Secondary 4 6 Elective Module 1 Automation Teacher s Guide Resource Materials Series In Support of the Design and Applied Technology Curriculum S4 6 Technology Education Section Developed by Curriculum Development Institute Institute of Professional Education Education Bureau And Knowledge PEAK The Government of the HKSAR Vocational Training Council Technology Education Section Curriculum Development Institute Education Bureau The Government of the Hong Kong Special Administrative Region Room W101 1 F West Block Kowloon Tong Education Service Centre 19 Suffolk Road Kowloon Tong Hong Kong Reprinted with minor amendments 2010 Project Advisor Mr Eric Liu Head Department of Multimedia and Internet Technology IVE Tsing Yi Author Mr Li Yu Wai Design and Technology Teacher Project Coordinators Mr Li Yat Chuen Senior Training Consultant PEAK VTC Mr Tsang Siu Wah Training Consultant PEAK VTC The copyright of the materials in this package other than those listed in the Acknowledgments section and the photographs mentioned there belongs to the Education Bureau of the Government of the Hong Kong Special Administrative Region Copyright 2009 Duplication of materials in this package other than those listed in the Acknowledgements section may be used freely for non profit m
25. PLC gives visual indication of an energized input Design and Applied Technology Secondary 4 6 a oe Li L2 Figure 3 2 3 Output circuitry of PLC Output signals are generated by the PLC s circuitry to activate a switching device transistor TRIAC or even an electromechanical relay connecting the Source terminal to any of the Y labelled output terminals The Source terminal is usually connected to the L1 side of the 120 VAC power source An indicating LED on the front panel of the PLC gives visual indication of an energized output L1 L2 Figure 3 3 Design and Applied Technology Secondary 4 6 4 Interfacing with PLC Once connected the PLC is able to interface with real world devices such as switches and solenoids The actual logic of the control system inside the PLC is established by a computer program This program dedicates which output gets energized under which input condition or status Although the program itself appears to be a ladder logic diagram with switch and relay symbols there are NO actual switch contacts or relay coils operating inside the PLC to create the logical relationships between input and output All these are imaginary contacts and coils The program can be entered and viewed through a personal computer which is connected to the PLC programming port
26. ain the washing machine typical operation of washing operation Topic 1 3 machine 5 Introduce the Assessment Task Question Lecture Classroom discussion Suggested answer in the Students understand the 02 1 Provide answer and conclusion to teacher guide assessment the assessment Do the correction Lecture and Demonstration Q amp A Take toilet bowl water tank Students understand the 03 1 Level control in fluid tank Topic Classroom discussion as an analogue example concepts of setpoint 1 5 proportional band and offset in control theory Lecture and Demonstration Hands on activities Electromechanical buggy if Students understand the 04 1 Control system in buggy if hardware any control logic of buggy control Topic 1 6 available and the use of electrical time delay in control oa Design and Applied Technology Secondary 4 6 Teaching and learning Assessment Period Teaching Activities Learning Activities Resources Competency Level Lecture 1 Q amp A Take an air conditioner in Student should understand the 05 1 Temperature and humidity control in 2 Classroom discussion classroom as an example concepts of control variables air conditioner and state output Topic 1 7 Lecture 1 Q amp A Supplementary notes in Student should understand the 06 1 1 Control systems types ON OFF 2 Classroom and Small Teacher guide level and characteristics of Proportional PID control group d
27. aking educational purposes only In all cases proper acknowledgements should be made Otherwise all rights are reserved and no part of these materials may be reproduced stored in a retrieval system or transmitted in any form or by any means without the prior permission of the Education Bureau of the Government of the Hong Kong Special Administrative Region A set of curriculum resource materials is developed by the Technology Education Section of Curriculum Development Institute Education Bureau for the implementation of the Design and Applied Technology Secondary 4 6 curriculum in schools The aim of the resource materials is to provide information on the Compulsory and Elective Part of the DAT Secondary 4 6 to support the implementation of the curriculum The resource materials consist of teacher s guides and student s learning resource materials of each Strand and Module of the DAT Secondary 4 6 arranged in eight folders All comments and suggestions related to the resource materials may be sent to Chief Curriculum Development Officer Technology Education Technology Education Section Curriculum Development Institute Education Bureau Room W101 West Block 19 Suffolk Road Kowloon Tong Hong Kong Sections 1 Principles 1 2 Concept Map 3 3 Key Concepts 4 4 Teaching Schemes 5 5 Sample Lesson Plans 9 6 Teaching Notes 23 EE EE O a a a ee REO ES Ge ae SHG PRESS SE GY OE S T ETE EE EEE CESSES ELS 7 Teacher
28. al to the feedback signal Within the proportional band the system is still under control and in a state of equilibrium around the setpoint 7 What is the meaning of error signal The error signal is the measured value from the feedback sensor in a closed Loop control system It is used to adjust the input value so as to keep the control system under control If the error signal is subtracted from the control value it becomes the negative feedback It means that if the controlled value goes beyond the setpoint the feedback signal will reduce the input value and make the output return to its desired value If the error signal is added to the control value it is known as the positive feedback It will make the system go unstable and uncontrollable from the setpoint It is rare in application Design and Applied Technology Secondary 4 6 8 What is the meaning of offset Offset is the magnitude of controlled output value from the setpoint 9 Describe how a Resistor and Capacity RC circuit can function as a timer An analogue RC electric circuit can be used as a delay timer A charged up capacitor will release electricity through a parallel connected resistor when the power is off The larger the resistance the longer will the capacitor take to discharge its electricity and thus can produce a time delay effect Vo Limit Switch D A Cc R Voltage at A Vo Limit Switch Limit Switch Time pressed released 10 Wh
29. at sensors can be used as a bump switch for an obstacle avoiding buggy Limit switch as an electrical on off switch can be used as a touch sensor to detect the presence of object It can be triggered by depressing a button or lever to make a contact Proximity sensors can also be used to detect an object which is close to the sensor Design and Applied Technology Secondary 4 6 TEACHER NOTES CHAPTER2 PNEUMATICS Why the output pressure will increase when the consumption flow rate drops and vise versa Can you account for this phenomenon Suggested Answers It is a scientific phenomenon and explained by the Bernoulli Theorem Itis stated that when there is a fluid flow in a closed or open channel the higher the velocity the lower becomes the pressure It is usually applied to explain the lifting force made by the aerofoil For a daily example when you are standing close to the yellow line in the MTR platform when a train is by passing you at a high speed you will feel a force attracting you towards to the train Why Due to the Bernoulli Theorem there is a pressure drop caused by the high speed train and the pressure drop generates a suction force to the people nearby What will be the advantages of a combined APU Suggested Answers A combined Air Handling Unit APU is a modular design which is composed of separate units of Filter Regulator and Lubricator It has the advantages of compact in size and ease of
30. attention Cruise control in a car and a house thermostat are common examples The controllers are used to automatically adjust some variable to hold the measurement or process variable such as water level temperature at the setpoint The setpoint is where you would like the measurement to be Error is defined as the difference between setpoint and measurement error setpoint measurement The variable being controlled is called the manipulated variable which is usually equal to the output of the controller The output of PID controllers will change in response to a change in measurement from the setpoint Manufacturers of PID controllers use different names to identify the three modes These equations show the relationships Proportional Band With proportional band the controller output is proportional to the error or a change in measurement from the setpoint controller output error 100 proportional band With a proportional controller offset deviation from setpoint is present increasing the controller gain will make the loop go unstable Integral action was included in controllers to eliminate this offset Integral With integral action the controller output is proportional to the amount of time the error is present Integral action eliminates offset Controller Output 1 Integral Integral of e t d t Design and Applied Technology Secondary 4 6 Integral action can eliminate the offset The resp
31. control of fluid level in a tank Use block diagrams to show the sub systems in a car e g the links between sub systems in a large system Explain the applications of control systems e g in a buggy air conditioner and production line and describe their control variables Pneumatics e Pneumatic components and symbols e Pneumatic circuits and systems e Electro pneumati c systems e Applications of pneumatic electro pneumatic systems Describe and illustrate examples of the use of pneumatics in daily life and industry Draw simple pneumatic circuit diagrams Design and use simple pneumatic electro pneumatic systems to solve control problems Understand the basic functions of different components in pneumatic systems e g valves cylinders filters regulators pumps sensors and solenoid Apply different components in pneumatic circuits Explore the control of cylinder motions e g speed regulation logic control and sequential control Design simple pneumatic circuits for solving control problems Discuss how pneumatic systems are applied e g automatic doors automated production lines and punching machines Discuss the advantages limitations and safety considerations of pneumatic control systems Design and Applied Technology Secondary 4 6 Topics Students should learn Outcomes Students should be able to Explanatory notes Programmable contr
32. ct management and provides appropriate technologies and knowledge for students to tackle the design challenge Learning Strategies Diversified learning strategies such as writing journals online blogs presentations group presentation demonstrations open competition reading to learn self directed reading and enterprise activities mini exhibition in campus are interweaved throughout the whole learning tasks Students are provided chances to develop their generic skills and solve real life problem They are expected to pursuit their learning outside the classroom B Design and Applied Technology Secondary 4 6 Period Allocation i 1 singl iod 2 doubl bes be 12 periods eno i sai as OUD e Teacher to students ratio 1 40 periods cycle periods Duration of each No of hours 22 hours period 40 mins Place ITLC and or DAT room iod Level NSS 2 Theme Design and Make Project Topics Robotics Teaching Scheme Period Teaching Activities Learning Activities Teaching and learning ney Resources Competency Level Project Briefing Students should A pipe test rig for Compare the 1 Teacher explains the project 1 Write a Design Brief demonstration advantages and requirements and overall 2 Compare the advantages and disadvantage of Some locomotive devices disadvantages of schedule different locomotive types and their fitness for the such as wheel drive and different loc
33. d provides a linear movement which can be used for direct drive for application of light loading OR used for controlling the movement of directional valve for cylinder control Electromechanical relay is a contact of either normally open or normally closed to provide an on an off switching for other devices of different power ratings 7 Why some applications prefer to use non lubricated pneumatic system For a clean and hygienic environment such as food pharmacy and electronic manufacturing of VLSI industry we need a lubrication free pneumatic system 8 Why cannot use two 3 2 NC spring return valve to directly control the double acting cylinder For a pneumatic training kit a double acting cylinder can be operated by two separate 3 2 NC signal valves However in real application it will not be the case as for safety considerations the compressed air to drive a double acting cylinder should not be directly operated by an operator 9 Why a shuttle valve must be present to perform an OR logic function If there is no shuttle valve connected between two 3 2 signal valves for OR operation the compressed air from one valve may go to the exhaust port of another valve through the crossed air line therefore no response from the cylinder TEACHER NOTES ON CHAPTER 3 PROGRAMMABLE CONTROL SYSTEMS What will happen if the value of input changes immediately after it has sampled during a scan cycle Suggested Answer In normal c
34. e the mechanical parts such as the pump to wear out or damage quickly and the frequent switching of electrical power will impose electrical and thermal stress to the electrical components b the response is so often and sensitive that it will cause overshooting and difficulties to maintain the state of equilibrium 2 Adopt the fuzzy logic so that the control will no longer be just an on and off action or use Proportional Integral and Derivative controller PID so that the overshooting can be minimized Teacher should remind their students that the System and Sub systems in section are introduced by a system engineering approach This means that it is interpreted macroscopically in a boarder sense Take the China Manned Spacecraft Shenzhou 7 as an example the whole project is regarded as a Manned Aerospace System however it is composed of 7 major sub systems such as Landing Ground Sub system Astronauts Sub system and Manned Spacecraft Sub systems etc Each Sub system are further decomposed into a number of sub systems in different level of scale and finally down to a component level AC power supply DC converter Power Sub system Charging dock Protection circuit Regulator Charging Sub system Detachable brush head Coupling mechanism Electric Toothbrush Cleaning Sub system Drive Sub system DC motor Power OMIOFF Speed Control Control Subsystem In another sense sub system can be explained in a
35. e to coordinate exhibition the interpreters for their own all the logistics and exhibition matters brochures robots 3 Bethe interpreters for their exhibition booths Suggested Follow Up Activities and Assignments This learning task has adopted the Wide Life Learning approach the final learning outcomes the pipe cleaning robots or the pipe inspection robots will be deployed in the events of presentation competition and exhibition Students have a lot of opportunities to develop their generic skills and work in an authentic learning environment They will gain experience through organizing competition and exhibition that will involve a lot of logistics and liaison works Students have the opportunities to train their interpersonal and communication skills They also have to commercialize their robotics through the Web and blogs In all these senses DAT teachers have a lot of opportunities to invite cross curricula projects with other subjects such as ICT languages Visual Arts BAFS Travel and Tourism etc Design and Applied Technology Secondary 4 6 Suggested Cross Curricula Teaching and Learning Activities DAT DAT DAT DAT DAT Design a Website with How to use Blogger enquiry and shopping cart function ities Verbal Presentation How to write press How to write exhibition How to write journal How to write blog release brochure VA Design and decorate Graphical design of the Design the e
36. ed as many times as necessary Each output in the PLC is also a bit in its memory An output Y status is actuated by assigning a contact in the PLC program The output contact can be used for a motor start stop control application Design and Applied Technology Secondary 4 6 L1 L2 j Motor start M1 oe J J t Motor Motor contactor stop X1 Figure 3 9 10 Motor control in PLC The pushbutton switch connected to input X1 as the Start switch while the pushbutton connected to input X2 as the Stop switch Another contact in the program is Y1 It uses the output coil status as a detent contact directly Thus the motor contactor will continue to be energized even after the Start pushbutton switch is released It can be shown by the normally closed contact X2 that appears in a coloured block showing that it is in a closed electrically conducting state When pressing the Start button input X1 would energize thus closing the X1 contact in the program sending power to the Y1 coil energizing the Y1 output and applying 120 volt AC power to the real motor contactor coil The parallel Y1 contact will also close thus latching the circuit in an energized state Design and Applied Technology Secondary 4 6 LI L2 Motor if start actuated M1 O Motor contactor energized
37. elays used in electromechanical relay circuits to provide logic signal inversion when necessary To demonstrate how one of these internal relays might be used the following example circuit and program can be considered to emulate the function of a three input NAND gate The internal control relay used is C1 E Design and Applied Technology Secondary 4 6 a ee oo L1 L2 s iS s Q Figure 3 15 In this circuit the lamp will remain lit as long as any of the pushbuttons remain unactuated unpressed To make the lamp turn off we will have to actuate press all three switches Design and Applied Technology Secondary 4 6 L1 All three switches 12 actuated lamp is dark Figure 3 16 The above examples just illustrate some basic capabilities of PLCs in general application Being functioned as a dedicated industrial computer PLCs can perform timing functions like time delay relays sequencing and any other advanced functions of greater accuracy and reliability than what are made using electromechanical logic devices Generally most PLCs have the capacity of more than six inputs and six outputs Design and Applied Technology Secondary 4 6 TEACHER NOTES ON CHAPTER 4 ROBOTICS STOP A N D T HINK Please state your reasons for the followin
38. emitted during the fire which will endanger the life of people Suggest any improvement plan to upgrade the fire safety system for your school There is no need to upgrade the fire safety system as high as those in the commercial building as the students are familiarized with the premises the storey of school building is not high and the building is not enclosed For more practical approach fire drill and the fire prevention education are more appropriate Design and Applied Technology Secondary 4 6 SUGGESTED SOLUTIONS TO THEME BASED LEARNING TASK 2 Learning tasks Part A 1 Construct the timing diagram 2 Construct the ladder diagram Cues my Heard Road Get R Red YO R Red Y3 Y Yellow Yte Y Yellow Y4 G Green Y2 gt G Green Y5 Output oc Xo m RO TY2 1Y3 oy Ro gt 70s gt R1 1Y2 TY1 AR R1 25s gt R2 1Y1 TYO HG R2 gt 2S gt R3 1Y3 TY5 HY R3 gt 10s gt R4 1Y5 TY4 AR R4 gt 5s gt R5 1Y4 tY3 VO assignment table Design and Applied Technology Secondary 4 6 Q MR 10s F O MR 5 I TMR Q o gt TMR 10s H a Os Part B 2 Tasks Choose a one way road with zebra crossing for this simple field study Reminded for the safety issues that students should be sta
39. eriods per cycle students ratio No of 12 hours Duration of 80 mins Place ITLC and or hours each period DAT room Level NSS 2 Theme Pneumatics Topics Theory and practical Design and Applied Technology Secondary 4 6 Teaching Scheme Period Teaching Activities Learning Activities Teaching and learning Resources Assessment Competency Level 01 Lecture 1 Introduction of air pressure and air preparation of Pneumatics Topic 2 1 1 Q amp A 2 Demo board Real objects and chart can be used for explanation Students can clearly define the various systems of pressure 02 Lecture 1 Explanation of Pneumatics circuit symbols Topic 2 2 amp 2 3 1 Q amp A 2 Worksheets Magnetic symbols for explanation Students can identify different types of symbols 03 Lecture and Demonstration 1 Explanation of basic Pneumatics circuitry Topic 2 4 1 Q amp A 2 Practical Magnetic symbols for explanation Authentic demonstration if Pneumatics kit available Students can design and draw simple Pneumatics circuits Topic 2 4 04 05 Assessment 1 Classroom and Magnetic symbols for explanation Students can design and 1 Explain the Assessment questions 2 small group Authentic demonstration if complete the tasks on their from 2 to 7 discussion Pneumatics kit available own 2 Feedback and suggested answers 06 07 Lecture 1 Q amp A Magnetic
40. f Control An on off controller is the simplest form of temperature control device The output from the device is either on or off with no middle state The air conditioner example in this chapter is this type An on off controller will switch the output only when the temperature crosses the setpoint For heating control the output is on when the temperature is below the setpoint and off when above the setpoint Since the temperature crosses the setpoint to change the output state the process temperature will be cycling continually going from below setpoint to above and back below In cases where this cycling occurs rapidly and to prevent damage to contactors and valves an on off differential or hysteresis is added to the controller operations This differential requires that the temperature exceeds setpoint by a certain amount before the output will turn off or on again On off differential prevents the output from making fast continual switching if the cycling above and below the setpoint occurs frequently On off control is usually used where a precise control is not necessary One special type of on off control is used for alarm This controller uses a latching relay which must be manually reset It is also used to shut down a process when a certain temperature is reached or danger happened Proportional Control Proportional controls are designed to eliminate the cycling associated with on off control A proportional control
41. f time even no leakage occurs and the power rating cannot support the loadings including the weight of the caged platform fire fighters and the victims 3 What are the limitations of using single acting cylinder The cylinder will retract automatically by the spring returning force when there is no signal held It will cause damage or error to an automatic production line in case of power failure Also the returning stroke cannot bear much loading because of the nature of spring force that also has limitation in heavy duty application 4 Suggest any methods to detect the leakage of compressed air in a manufacturing plant 1 Revealed by the pressure drop in pressure gauge A number of pressure gauges can be installed along the pipeline as the checkpoints Leakage can be revealed by soaking soap water along the suspended pipeline 3 Sometimes leakage can be found by hearing However it does not work in a factory environment 5 What is the major reason of using Electro pneumatics The reason of using electro pneumatics is mainly for the interfacing with the digital world Most of the industrial automatic control system adopts Programmable Logic Controller PLC which can energize a control relay and signal to solenoid to control the movement of valve position Design and Applied Technology Secondary 4 6 6 Describe the differences of Solenoid and Electromechanical relay Both of them are electromechanical device Solenoi
42. g questions 1 Are movable machines such as cars Robot 2 Are computers Robot Suggested Answer 1 Nowadays most of the cars have a computer inside and preprogrammed to facilitate the driver for better controllability and comfort Most of the times the decision making is still made by the driver Thus cars have mobility but cannot be regarded as robot 2 Computers are not regarded as robot as it does not have the locomotion on their own Referring to the Robot Control System no matter what drive systems such as Electric Pneumatic and Hydraulics to be adopted for the robotic joint control it can be typically depicted in the following block diagram Reference Angle R Setpoint Error Signal e Actual Joint Position Measured Joint Position The actuators can be stepping AC servo solenoid pneumatic or hydraulic cylinder Referring to the type of robot control teacher should explain to the students that the Limited Sequence Robot may not be regarded as robotic control in accordance to the strict definition of Industrial Robot It is now rarely be used in today industrial application as it is lack of programming and reprogramming It is just an application of hard wired automatic control in some simple industrial application Definition of Industrial Robot A computer controlled re programmable mechanical manipulator with several degrees of freedom capable of being program
43. h as PLCs pneumatics and electro pneumatic We have no preferences or implications to use any specific hardware kits and equipments available in the market DAT teachers are free to adopt any teaching aids to deploy their lessons in accordance to their professional knowledge and their students needs as long as the key concepts and the learning objectives are met Examples of local contexts which are supposed to be more familiar to our students are recommended to our daily classroom teaching At the same time students are encouraged to keep their eyes open to the emerging of state of art technology in global sense CURRICULUM PLANNING The arrangement of four chapters does not imply the teaching sequences except chapter 1 Basics of Control System is recommended to be taught first as a foundation to build up concepts of control theory Students are recommended to complete one chapter fully before going to the next It includes the completion of all after chapter quizzes the relevant theme based learning tasks and assessment tasks The availability of teaching aids and the readiness of teachers students can be the factors affecting the teaching sequences and schedules E Design and Applied Technology Secondary 4 6 S4 Compulsory part S5 Automation Topic 1 Topic 2 Coursework 4 S6 Automation Topic 3 Topic 4 Table 1 Suggested Teaching schedule for the Automation module LEARNING AND TEACHING DAT i
44. her air piloted 3 2 valve with separate air flow of higher pressure can be connected Design and Applied Technology Secondary 4 6 db Suggested Solution To Question 3 This case can be simplified by just considering the clamping operation of the workpiece Only a control of extend and retract of double acting cylinder is needed The drilling action is still operated manually Suggested solution to Question 4 The task is to make sure that both the workpiece is firmly clamped and the safety guard is properly closed This can be represented by a logic AND in the circuit Then the operator will press the Start button to trigger the single acting cylinder to start the press operation The two 3 2 valves on the left represent the closing of safety guard and the clamps The 3 2 valve on the right represents the Manual start switch The lower AND can be omitted by connecting the two 3 2 valves in series Design and Applied Technology Secondary 4 6 Suggested solution to Question 5 The operation can be considered as logic OR It is because either the conveyor is accumulated with work pieces or the gate is closed the technician will press the button to trigger the double acting cylinder to open the gate The closing of two 3 2 valves on the left represents the conditions of full of accumulated parts and the gate is already closed are met stp Suggested solution to Question 6
45. in classroom 3 Topic 1 3 Operation of washing 1 0 RM in classroom machine 4 Topic 1 4 Operation of traffic lights 1 0 RM in classroom 5 Topic 1 5 Control of fluid level in a 1 0 RM in classroom tank 6 Topic 1 6 Application of control 1 0 RM in classroom systems in a buggy 7 Topic 1 7 Application of control 2 0 RM in classroom systems in an air conditioner 8 TLT 1 Practical Design 0 6 RM in classroom Graded appreciation Case Study of assignment Intelligent Fire Alarm System 9 Assessment Tasks Question 1 0 2 RM HO DM in special Graded Basics of Control Systems room assignment Total Hours 8 8 Table 3 Detailed Plan for delivery of Chapter 1 Chapter 2 Pneumatics No Topic Hrs Type of delivery Remarks T C 1 Topic 2 1 Pressure 2 0 RM in classroom 2 Topic 2 2 Pneumatics Components and 2 0 RM in classroom Symbols 3 Topic 2 3 Understanding Pneumatic 2 0 RM in classroom Components 4 Topic 2 4 Pneumatic Circuitry 3 0 RM in classroom 5 Topic 2 5 Electro pneumatic Systems 3 0 RM in classroom 6 Quizzes 0 4 RM HO DM in Graded Assessment Tasks Question 2 7 special room assignment Total Hours 12 4 Table 4 Detailed Plan for delivery of Chapter 2 B Design and Applied Technology Secondary 4 6 Chapter 3 Programmable Control Systems
46. ine etc These examples are used to illustrate the concepts of open loop closed loop sequential and logical control etc Students are expected to understand some terminology in the discipline of Automation such as open loop closed loop proportional band offset equilibrium feedback error and so on After completing this chapter students should become confident in appraising basic control systems CHAPTER2 PNEUMATICS The key concepts of this topic range from understanding pneumatic basics and components to the application of pneumatics and electro pneumatic circuits in industrial settings Practicing DAT teachers should have been familiarized with the topic of pneumatics therefore attention should be given to solenoid valve and the hands on activities of electro pneumatics circuitry More practical industrial applications are included for senior secondary students CHAPTER3 PROGRAMMABLE CONTROL SYSTEMS The key concepts of this chapter are the application of Programmable Logic Controller PLC ladder logic diagram Programmable Interfacing Controller PIC and some electrical actuators Focus should be given to the understanding of ladder logic and the programming of PLCs The introduction of PIC in this chapter is to provide students with the basics of interfacing with other electric components which will be very useful for preparing their final year project CHAPTER4 ROBOTICS The key concepts of this topic are the understanding of
47. ineers and maintenance personnel The PLC has the advantage over the computer that it is designed to operate in an industrial environment with vibration and unstable ambient temperature and humidity PLCs are also immune to electrical noise that is present in most industrial applications Though PLCs and computers are alike but differ in many ways the computers besides handheld programmer are often used for programming the PLC 8 Convert the logic diagram into a ladder diagram and write a Boolean expression for it Design and Applied Technology Secondary 4 6 A B Z Z A B C D 9 What are the usage of tilt switch and Reed switch Tilt switch is used to detect the orientation of the controlled element Two contact points are immersed inside liquid mercury inside a capsule If the capsule is not in an upright position the contact will become open circuit It gives a signal of 0 for a tilted situation The reed switch is either a pair of closed or open contact point once the magnetic force is near the contact will be either pulled apart or drawn close by the attractive force the switch is then open or close relative to its original position It is usually used in security application such as install in window frame 10 List three advantages for stepping motors and servomotors Any 3 of them for the advantages of stepping motors Moves in discrete step angle by an electrical pulse train No brush in constructio
48. ion and correction during the motion cycle 6 What will be the possible limitations of using surgery robot through Internet An inevitable time delay in video signal transmission is very critical in real time remote control operation through internet Ee EEEE S ciao ree Design and Applied Technology Secondary 4 6 m ir Se 7 Which of the followings are regarded as robots State your reasons a b c d Figure a above is not a robot and it is just an walking machine by mechanical means Figure b c and d are robots as they are all programmable They have an end effector to execute the control program and have their own means of locomotion Design and Applied Technology Secondary 4 6 SECTION 7 TEACHERS NOTES FOR THEME BASED LEARNING TASKS Suggested solutions to Theme based learning Task 1 1 Investigative Questions Students are expected to form groups by conducting information search through Internet and small group discussion to answer the following questions A Explain why the Intelligent Fire Alarm system does not use the pre pressurized sprinkle system but use the dry pipe To avoid damage caused by the false alarm especially in the area of containing dedicated equipment such as the server room or computer room No matter how advanced the technology it is inevitable that there is a chance of false alarm such as intruders or high h
49. ircumstances the period of scan cycle is so short that any significant physical changes in input value that will cause damages to the controlled element is less likely to happen However if this extreme situation really happens PLC will keep on reading the input status several times during a scan cycle and update the input valve whenever there is change detected Increasing the speed of scan cycle can also minimize the risk of input value changes during the scan cycle Design and Applied Technology Secondary 4 6 Se ME Os A N D T H IN K What will happen to the above solenoid design in case of power failure during the course of control Would you suggest any modification to alleviate this problem Suggested Answer In case of power failure the solenoid is de energized The spring will extract the core out of the coil This may result in damage to the process being controlled A double acting solenoid can be used to avoid this problem The core can be driven in either direction by just reversing the polarity of the coil In case of power failure the core will remain in the last position until the power resumes but not extracted by the spring force EXERCISE SEQUENTIAL CONTROL OF DRILL AUTOMATION Suggested Answer It should be reminded that there might be more than one solution to this type of problem Usually the solution that can fulfil the task and with minimum number of components will be regarded as the best one The f
50. iscussion these control types optional Design and Applied Technology Secondary 4 6 MODULE 1 AUTOMATION TEACHING SCHEME SAMPLE 3 Chapters 2 Pneumatics Aims and Objectives Students should have an understanding of Pneumatics symbols components and circuitry after taking this chapter A scientific definition of air pressure will be included at the early section Electro pneumatics will be taught in this chapter that will also be the fundamental knowledge for the PLC in chapter 3 Students can gain some practical and engineering know how in the application of Pneumatics to tackle some industrial problems Teaching Strategies 1 Teacher plays the role as an instructor if there are pneumatics kits available for practical activities 2 Teacher can provide worksheets to assess students understanding of theory and practical tasks 3 Teacher can explain the mechanical structure and principle of valves as supplementary information to arouse the interests of students Learning Strategies 1 Small group discussion quiz and verbal presentation will be effective ways of collaborative learning and consolidation of knowledge 2 Students should spend times to conduct extensive readings of magazines books and articles relevant to this topic to build up a strong foundation for their further studying Period Allocation No of 9 periods No of Periods 1 double periods Teacher to 1 40 p
51. ler decreases the average power supplied to the heater as the temperature approaches setpoint This has the effect of slowing down the heater temperature rise so that it will not overshoot the setpoint but will approach the setpoint and maintain a stable temperature E Design and Applied Technology Secondary 4 6 This proportioning action can be accomplished by turning the output on and off for short time intervals This time proportioning varies with the ratio of on time to off time to control the temperature The proportioning action occurs within a proportional band around the setpoint temperature Outside this band the controller functions the same as an on off control unit and the output will either be fully on below the band or fully off above the band However within the band the output is turned on and off in the ratio of the measurement difference from the setpoint At the setpoint the midpoint of the proportional band the output on off ratio is 1 1 that is the on time and off time are equal If the temperature is further from the setpoint the on and off times vary in proportion to the temperature difference If the temperature is below setpoint the output heater will be ON longer if the temperature is too high the output heater will be OFF longer PID Control PID stands for Proportional Integral and Derivative It is the controller designed to eliminate the need for continuous operator
52. lication however the slide unit has a built in double cylinder rod which has a higher rigidity without the risk of buckling and has a higher output force A single acting cylinder seems not suitable for this application STOP AND THINK One of the advantages of pneumatic system is theoretically no cost at all as the supply of air is free in the atmosphere Therefore in the above case why engineers design an automatic system to reduce the wastage of compressed air Design and Applied Technology Secondary 4 6 Suggested Answer Yes the air is free supply from the atmosphere However once the compressed air is released from the nozzle the pressure in the pipeline will drop The air compressor will automatically be switched on to compensate for the pressure loss Therefore the design can cut the electricity cost by 50 SUGGESTED ANSWERS TO THE QUIZZES CHAPTER 2 1 What are the limitations of using Pneumatics Compressible air is the major limitation of Pneumatic especially in the application requiring high precision and heavy loading Therefore you can easily find that the applications used for critical situation will adopt hydraulic instead of Pneumatics such as the canon turret in tank or the sky lift ladder in fire engine 2 Why the elevator in fire engine cannot be driven by Pneumatics The air is compressible If the sky lifts use pneumatic it cannot be held in the required position for a prolonged period o
53. lows smooth integration with Flexible Manufacturing System and CNC machine such as in automotive industry Today s production lines require accurate reliable high speed and highly repetitive processes that the manual operation seems not capable of meeting this requirement Automated manufacturing operation has higher production rates than the manual operations Automated production has a lower price and better products The benefits of automation also come with better company images and maintain a competitive advantage with their customers and general public in additional to improved quality higher sales and better labour relation 2 State the differences between Open Loop and Closed Loop control system Open Loop control is a direct and simple control system The controller is used to send signal to the controlled element for the desired value or setpoint i e certain temperature in a room or in an oven However there is no feedback to tell the controller that the setpoint or desired value has been reached or not For a closed Loop control system a feedback signal is returned back to the controller to tell that the controlled value has reached the setpoint or not The discrepancies between the desired value and the actual value are compared to give an error signal The feedback signal serves a self regulating function with a view to minimize the range of error and get close to the setpoint The closed Loop control system is complex but in
54. med to carry out one or more industrial tasks Design and Applied Technology Secondary 4 6 STOP AND T H IN K Please state your reasons for the following questions 1 Why articulated robots are commonly used in welding process in industrial application Please state your reasons 2 What are the limitations of Cartesian robots used in this application Suggested Answer 1 An articulated robot is the one alike a human arm with greatest flexibility The welding process is very complex and skilful The whole process is programmed to the robot by the method of Leadthrough This means the welder physical leads the end effector of robot to the exact location throughout the welding process The location of each point is stored and programmed to the robot Articulated robot is the only one which can reach the workpiece underneath and overhead 2 If Cartesian robot is used for welding it cannot reach the workpiece underneath and the size of the robot will be very huge and sometimes a gantry one will be used Nee M Oe A N D T H IN K 1 What will be the number of mobility DOM and number of freedom DOF for a telescopic arm which has 4 steps of extension DOM DOF Suggested Answer DOM is 4 as the link joint pair but the DOF is only one as it just extends outwards Design and Applied Technology Secondary 4 6 Se ME Om ia A N D T HIN K Can you use the Joint Notation Scheme to describe
55. n low maintenance cost High holding torque at standstill No need for brake or clutch in application Usually used in open Loop control system application low cost because of no sensors are needed Any 3 of them for the advantages of servomotors fast positioning high peak torques wide speed ranges high controllability Design and Applied Technology Secondary 4 6 aa a r FURTHER EXPLANATORY NOTES Examples of using Typical Programmable Logic Controller Signal connection and programming protocol may vary between PLCs of different brands and models The principle is basically more or less the same therefore generic introduction of PLC programming are still worthiness The following illustration shows a simple PLC connection 1 Configuration of a typical PLC Two screw terminals labelled L1 and L2 provide connection to 120 volts AC for powering the PLC s internal circuitry Six screw terminals on the left hand side provide connection to input devices and each terminal represents a different input channel The Common connection is generally connected to L2 neutral of the 120 VAC power source Figure 3 1 2 Input circuitry of PLC An opto isolator device Light Emitting Diode is connected between each input terminal and the common terminal inside the PLC housing LED provides an electrically isolated high logic signal to the circuitry An indicating LED on the front panel of the
56. nding in a safe area to conduct this study Students should record the sequence of the pedestrian and vehicle lights and then measure the corresponding time period Observe the changes in timing after the walk button is pressed Make reference to the previous question for drawing the timing diagram and ladder diagram but use the real field data SUGGESTED SOLUTIONS TO THEME BASED LEARNING TASK 3 In order to cater for learners diversity students can feel free to adopt any level of technology that he she may feel comfortable and as long as the task can be accomplished For those who are familiarized with IC electronics micro controller and programming they can design and make their autonomous robot However for general students a real time cabled remote control of DC motors is also acceptable This can simply be done by manually switching a DTDP switch to change the polarity direction of the motors Bear in mind that arousing students interest and creativity come first in this learning task The challenge can leave to the innovative design of end effectors Design and Applied Technology Secondary 4 6 To DC Supply V DTDP Switching Circuit To DC Supply V To DC Motor 2 To DC Motor 1 A real time transmission of video signal by cable or wireless can easily be made by the kit available in local electronic shacks that will be more fun to this project Teacher can arrange students in form of g
57. ng tasks are used for the practicality and cater for the learning diversities The four chapters are complementary and supplementary to one another Chapter 1 underlies the principle of sequential control closed loop systems and sub systems This chapter will use the operation of washing machine buggy air conditioner and production line as an elaboration Chapter 2 will illustrate the application of pneumatics and electro pneumatics systems It somehow involves the PLCs which will be discussed in chapter 3 for the control of electro pneumatic system In chapter 4 it deals with the basic of robotics in a qualitative approach The examples of using Programmable Interface Controller are also introduced in chapter 4 After completing this module students should have confidence and competence to solve technical problems or carry out design projects with demand of automatic control and be able to solve problems in a system approach TEACHER NOTES CHAPTER 1 BASICS OF CONTROL SYSTEM 1 Suggest any disadvantage of this type of temperature and humidity control 2 Suggest any method that can improve this overall control system Design and Applied Technology Secondary 4 6 Suggested Answers 1 When the control value is derivated over or lower from the set point the actuator such as the heating coil and the humidifier will be turned on and off frequently The problem will be in two folds a the frequent switching will caus
58. nology Secondary 4 6 9 2 Reference Books A TRE Ea 2007 E BIZE Ea RREO TT AR TRA HK E Groover M 2000 Automation Production Systems and Computer Integrated manufacturing NJ Prentice Hall Jones J L Flynn A M 1998 Mobile robots inspiration to implementation AK Peters Ltd Mitchell F H 1991 CIM Systems An Introduction to Computer Integrated Manufacturing Englewood Cliffs Prentice Hall Design and Applied Technology Secondary 4 6 9 3 Learning Objectives of Automation Module I Automation Extracted from the Design and Applied Technology Curriculum and Assessment Guide S4 6 This module enables students to explore the design of control systems It focuses on the basics of systems pneumatic control programmable control and robotics Topics Students should learn Outcomes Students should be able to Explanatory notes Basics of control systems e Sequential control systems e Closed loop systems e Sub systems Interpret sequential control systems Interpret closed loop control systems Interpret the stages and functions of sub systems in a system Evaluate products with control functions Examples of sequential control system e g operation of a washing machine and traffic lights Illustrate the key components in a closed loop system e g investigate the
59. ol systems e Basic working principles of programmable control systems e Use of programmable control systems e Problem solving 8 9 10 11 Understand the basic working principles of programmable control systems Use programmable control boards and kits Select input and output devices in programmable control systems Construct simple architecture of a programmable control system Explore the basic Interpret the use of interfaces and I O ports digital and analogue ports Use of sensors and output devices e g stepper and servo motors Use of various programmable control tools such as programmable logic controllers PLCs micro controller boards or learning kits and personal computers using Explain how programmable control programmable programmable control systems are driven by the following control systems to solve Personal computers technology control problems Micro controllers 12 Understand the PLCs mdusthalappheatiuns Use of application software for data pipo irmmable capturing logging process controlling and control systems power driving e g the design of a computer controlled fire alarm system Discuss the applications of programmable control and their advantages and limitations Robotics 13 Understand the basic Explain the components of a simple robot e Basic structure of configuration of robot arm e g programmable mechanical robot arms arms manipulator end effector structure join
60. ollowing two solutions are of reference only You and your students may try to get a better answer The solution can be verified by a PLC simulation program or tested by hardware setting if either of them is available START Input Output Assignment Table For the above application students should be able to construct an input output assignment table for any PLC programming so as to indicate how it will be connected and what control variables I O to be controlled Design and Applied Technology Secondary 4 6 M1 Drill Motor M2 Feed Motor LI Upper Limit Switch L2 Lower Limit Switch C1 Internal Control Relay 1 C2 Internal Control Relay 2 Exercise Control of traffic light Suggested Answer R4 RO RO 2s R2 R4 R2 TMR C R2 oO wi R3 R4 oq QO 05 R3 Fa RO R1 R1 R2 R2 R3 Why use EEPROM memory for PIC Design and Applied Technology Secondary 4 6 Suggested Answer It is almost impossible to write an absolute correct program at once It needs to be trial and error to get an ultimate possible solution EEPROM provides convenience for the programmers to modify and update the program during the design stage Ne ME Om oa A N D THINK Can you suggest one application of i servomotor and ii stepping motor with an appropriate reason Suggested Answer i RC models almost adopt DC servo for their applications Fast
61. omotion 01 2 A pipe test rig is provided for design purpose belt drive for Complete a reflection demonstration Different types of 3 Form a group of 3 for the design project demonstration journal in the locomotion and cleaning devices Interactive Learning are provided for promoting ePlatform students creativity Write a Design Brief Concepts Building and Group Students should Large colored drawing Submission of Presentation 1 Prepare comprehensive Mindmap papers sign pens and Mindmap 1 Teacher illustrates Mindmap 2 Understand design factors and considerations color pens Peer Evaluation 02 formulation and requirement of 3 Understand assessment criteria for the peer Prepare r group group presentation evaluation presentation 2 Teacher explains the method of 4 Prepare group verbal presentation evaluation and assessment 3 Teacher takes a facilitator role for Design and Applied Technology Secondary 4 6 Teaching Activities Learning Activities Teaching and learning Resources Assessment Competency Level the group discussion Group Verbal Presentation Students should Microphone and Conduct group 1 Teacher conducts the student 1 Conduct 10 minutes group presentation networked computer may presentation group presentation 2 Deploy a well organized and good allocation be required assess the 03 of work Video taking of presentations presentations P
62. ompletely Most of the times it doesn t This phenomena is called hysteresis If you put a large force on your fork while cutting a tough piece of meat it doesn t always return to its original shape The term is usually applied to magnetic materials Suggested answer to Quizzes of chapter 1 1 Why automated control systems are so important in industry From the economical point of view automation reduces the need for skilled labour which usually involves higher salary The manual works left in an automated production line only require labour skills of lower level such as loading and loading of parts changing tools and removing materials chips This gives rise to a reduction in the labuor force in an automated industry because fewer workers are needed for these menial tasks The industry shifts from the labour intensive operation to an automated machine operation the cost for higher labuor salary are reduced As a result the cost per unit of product is lower Also the 7 x 24 hours non stop operation by automated machines has maximized the throughput of the production line thus the output per hour per labour input can be achieved Also the shortage of appropriate skill level labour is the reason for manufacturers to adopt automation to substitute Design and Applied Technology Secondary 4 6 labour From the technical point of view automation has no allowance for human error such as tiredness and absent mindedness It al
63. onse is oscillatory and can be stabilized by adding derivative action Integral action gives the controller a large gain at low frequencies that results in eliminating offset and beating down load disturbances Derivative With derivative action the controller output is proportional to the rate of change of the measurement or error The controller output is calculated by the rate of change of the measurement with time dm CONTROLLER OUTPUT DERIVATIVE dt Where m is the measurement at time f Derivative action can compensate for a changing measurement Thus derivative takes action to inhibit more rapid changes of the measurement than proportional action Derivative is often used to avoid overshoot How to construct state diagram 1 1 Input 1 0 S1 S1 S2 S2 S2 S1 OAA State Transition Table an State 0 In sequential control logic a state transition table is usually employed to indicate the state change It is actually a truth table showing what will be the output state which is based on the current state and other inputs In the above state transition table the vertical dimension first column indicates current states which are regarded as one of the inputs The horizontal dimension second and third row indicates the next state first row S and Sz represent the single bits 0 and 1 two states If the current state of the system is in S1 the first row and the next input is 1 the out
64. osted on web for sharing Formulation of Possible Preliminary Students should A3 drawing papers Submit 3 annotated Designs 1 Propose 3 possible design solutions pencils and colored design sketches 3 Teacher clearly states the 2 Prepare at least 3 annotated sketches for pencils Conduct selection of requirement of the design demonstration Demonstrate drawing design process drawings techniques Provides feedback 04 4 Teacher demonstrates some Digitalize the design essential drawing and rendering sketches for portfolios techniques 5 Teacher provides consultation to students during the brainstorming stage Computer Control of Locomotive Students should Apply different types of Complete a Drive 1 Understand the differences of DC and servo motor circuit boards reflection journal in 1 Teacher demonstrates motor motors gearbox and mobile the e Learning directional and speed control 2 Transfer the control technologies of DC platform Platform 05 2 Teacher explains underlying motors and servo motors to designed robots Self directed principle advantages and readings of data disadvantage of motor controls sheets websites reference materials E Design and Applied Technology Secondary 4 6 Period Teaching Activities Learning Activities Teaching and learning Assessment 3 Teacher demonstrates DC motor and servomotor control Resources Competency Level Demonstration of Video
65. ove circuit if the valve 1 is still pressed even when the valve 2 is tripped at the end of the outstroke 2 Would you suggest any modification to the circuit to improve this situation ea Design and Applied Technology Secondary 4 6 Suggested Answers 1 It is known as overlapping of commands the cylinder rod will not retract until the valve 1 is released 2 Use a momentarily press button instead of a press button with latch function For the cases above would you suggest the reason for a what types of cylinders should be used b Air piloted or solenoid control valves will be used in this application Suggested Answers a For the left case in Figure 2 44 a slide unit is recommended for use Slide unit has two parallel rods and it is suitable for carrying loads because of better rigidity The slide can detent in position until the next signal arrives For the right case a single acting cylinder is recommended for use There is a need for quick action and the actuator needs to be returned and ready for the next action b Actually either air piloted or solenoid control valve can be used However the production line is usually controlled by PLC the solenoid valves seem to have better interfacing with the control system List the reasons why the slide unit is used for the above application but not the cylinder Suggested Answer Actually a double acting cylinder can also be used for this app
66. pace and complicated 4 Give a brief description of what a PLC is By the definition of PLC from National Electrical Manufacturing Association NEMA PLC is a digitally operating electronic apparatus which uses a programmable memory for the internal storage of instructions for implementing specific functions such as logics sequencing timing counting and arithmetic to control through digital or analog input output modules various types of machines or processes A Programmable Logic Controller PLC is a solid state system designed to perform the logic functions which are previously conducted by components such as electro mechanical relays limit switches mechanical timers counters etc for the control and operation of manufacturing process equipment and machinery They are a specific form of computer that is dedicated to be used mostly in industrial applications to read inputs make decisions based on a control program and control outputs to automate a process or machine 5 Can PLC be regarded as a computer If not Why PLC consists of some of the computer hardware but is not regarded as a computer A PLC is used to be programmed for the operation of individual logic and sequence elements that might be contained in a bank of relays counters and other hard wired components Computer is more than a PLC in the hardware configuration Design and Applied Technology Secondary 4 6 6 What is the history of PLCs Richard E Mo
67. plication of control systems in a buggy Topic 1 7 Application of control systems in an air conditioner Theme based Learning Task TLT 1 Practical Design appreciation Case Study of Intelligent Fire Alarm System Assessment Tasks Question 1 Basics of Control Systems Chapter 3 Programmable control systems Chapter 4 Robotics Topic 3 1 What is Programmable Logic Controller Topic 4 1 Definition of Robots PLC Topic 4 2 Mechanical structure of Industrial Topic 3 2 Programming the PLC Robotic Arms Topic 3 3 Application of ladder Logic Diagram Topic 4 3 Robot Anatomy Topic 3 4 Programmable Interface Controller Topic 4 4 Robot Control Systems S6 Topic 3 5 Stepper Motor and Servomotor Topic 4 5 Application of Robots Theme based Learning Task 2 Hands on Activity Controlling an automated traffic lights using programmable logic controller Assessment Tasks 8 10 PLC Theme based Learning Task 3 Design and Make Project Pipe Cleaning Inspection Robot Theme based Learning Task 4 Mars Exploration Design an innovative End effector for Mars Lander Table 2 Teaching scheme in senior secondary level 5 to 6 oe Design and Applied Technology Secondary 4 6 DETAILED SCHEMES Chapter 1 Basics of Control System No Topic Hrs Type of delivery Remarks 1 Topic 1 1 Open Loop Closed Loop 1 0 RM in classroom and Sequential control systems 2 Topic 1 2 System and Sub systems 1 0 RM
68. put state will stay in S1 If the next state is 0 the output state will transit to S2 in the third column If the system is in S2 as the current state and the next state is S1 the output state will remain in S2 If the next state is in S1 the output state will transit to S1 oe Design and Applied Technology Secondary 4 6 ae T ena FURTHER EXPLANATORY NOTES What is SSR SSR is the short form of Solid State Relay It is actually not a relay at all There is no relay present just the electronics which does the switching A Solid State Relay SSR is an electronic switch which unlike an electromechanical relay contains no moving parts The types of SSR are photo coupled SSR transformer coupled SSR and hybrid SSR It works the same way as a relay It can be used for a low voltage to switch to a higher voltage What is RTD Resistance thermometers also called Resistance Temperature Detectors RTDs are temperature sensors Their working principle is depending on the calibrated change in electrical resistance of some materials with the changing temperature The material is commonly made of platinum and they are often called Platinum Resistance Thermometers PRTs They are going to replace termocouples in many industrial applications below 600 C What is hysteresis Hysteresis can be explained by the following daily examples If you push on something it will yield when you release does it spring back c
69. rely who founded the Modicon Corporation invented the first PLC in 1969 and was the result of specifications initiated by the General Motors Corporation GM The automotive industry had traditionally been a large buyer and user of electromechanical relays to control transfer lines mechanized production lines and other automated systems GM prepared the specifications for a Programmable Logic Controller in 1968 in an effort to reduce the cost of new relays purchased each year Several companies saw a commercial opportunity in the GM initiative and developed various versions of a special purpose computer which were now referred as PLC 7 Why PLCs are more commonly used for industrial applications than computers PLCs are dedicated design for industrial use in terms of compatibility and reliability They are free from hang and virus that computers must come across in operation Computers may be used to program the PLC in the early stage A computer can store hundreds of application and utility programs and run many different types of software each one with the ability to crash the system without warning This will result in usual system breakdown This is unacceptable in industrial applications Today PLCs have been widely adopted in industrial automation One of the main reasons for their success is that they can be programmed and operated by individuals who do not have strong backgrounds in computer programming such as plant eng
70. replacement and maintenance Some pneumatic system will omit the lubricator to provide a clean air for some application such as food electronic or pharmacy industry The lubricator can easily be attached from the combined APU without too much system configuration See M Os A N D T HIN K Would you describe briefly the following two valves to see how much you understand at this stage a b B Design and Applied Technology Secondary 4 6 Suggested Answer a It is a 3 2 3 ports and 2 positions directional valve It is mainly used as a signalling valve or control valve for direct control of single acting cylinder without flow amplification in case of manual control b It is a 5 2 5 ports and 2 positions directional valve It is usually either air piloted or solenoid driven for controlling double acting cylinder The exhaust ports are represented as T in the symbol but physically it has no port the exhaust air with low pressure will release directly to atmosphere STOP AND THINK Why the air pressure fluctuates within the plants Please list any 4 points 1 2 3 4 Suggested Answers Here are the possibilities Maybe the problem of pressure gauge Leakage in working pipeline The pressure supply capacity cannot cope with the requirements from the system The malfunction of the air compressor Pee ee See We Oe A N D T H IN K 1 What will happen in the ab
71. response and the use of closed Loop control system are the major advantage of using DC servo for this application ii Stepping motor can be used for the volume control in Hi fi Usually the volume control knob can be remote controlled The characteristics of stepping motors for low acceleration of static load high precision positioning and high holding torque at a standstill position can suit for this application Design and Applied Technology Secondary 4 6 SUGGESTED ANSWERS TO THE QUIZZES CHAPTER 3 1 Name the 6 major components of a typical PLC Input module Output module Processor Memory Power supply and Programming device 2 What are the three main steps of each scan cycle performed by a PLC Step 1 Check Input Status Step 2 Execute Program Step 3 Update Output Status 3 What are the drawbacks of using electromechanical relays in automated control Electromechanical relay is large in size and complicated in structure compared with PLC It takes up a lot of space especially for relays of high voltage and power ratings They are hard wired to perform designed logic functions so they are difficult to modify or update a system Electromechanical relay has inherited a limited service of life as they have many moving mechanical parts inside the devices i e springs and contacts They require separate hard wired timers and counters for performing delay and timed logic functions which make the system take up more s
72. rning and consolidation of knowledge 2 Students should have hands on activities in PLC programming and control if hardware kits are available for better understanding of this topic 3 Students are encouraged to tackle the Thematic Learning Task 4 after taking this chapter Period Allocation No of 8 periods No of Periods 1 double periods Teacher to 1 40 periods per cycle students ratio No of 10 hours Duration of 80 mins Place ITLC and or hours each period DAT room Level NSS 3 Theme Programmable Topics PLCs and Logic Controller Ladder Logics Design and Applied Technology Secondary 4 6 TEACHING SCHEME Period Teaching Activities Learning Activities Teaching and learning Resources Assessment Competency Level Lecture 1 Q amp A Resources package Students can clearly define 01 1 Introduction of PLC theory and working 2 Stop and Think the various parts of PLCs principles Topic 3 1 Lecture and demonstration 1 Q amp A PLC simulation software should be Students should fully 02 1 Explanation of PLC control theory and 2 Classroom used for demonstration Freeware understand the PLC logic and programming Topic 3 2 discussion may be available programming Lecture and demonstration 1 Classroom Magnetic symbols or simulation Students should fully 1 Explanation of ladder logic discussion program should be used understand the ladder logic 03
73. roups and work in pairs The tasks can be divided into several subtasks for the students to tackle and overcome 1 Students try to control the DC motors and make the chassis move Students can determine the locomotive method by wheels terrace or mixed mode Students design the motor control to make the chassis move under control Students can test the video signal transmission and design the mounting device Students design the end effector for cleaning or inspection purpose Pe le Finally students can have a demonstration and presentation for the completion of project Suggested solutions to Theme based learning Task 4 Notes to teachers Students are expected to conduct information search from Internet or books about the tasks needed to be done in MARS Exploration Program and study some basic information about the MARS environment Students are required to present the design sketches before making the models or prototype for realization and testing This learning task can be conducted in form of competition and let students learn with fun and motivation Design and Applied Technology Secondary 4 6 A Efficiency is referring to how fast the end effector can do the job in the Mars exploration scenario such as picking up the samples and clearing of obstacle Effectiveness is referring to how good the end effector can do the job Actually a two finger picking up end effector can manage to do the job However for the sake of
74. rrupted Rung 2 When the counter reaches 0 the counter contact will close and energize the control relay which is used to actuate the eject mechanism i e a single acting cylinder Rung 3 The eject mechanism output is used as an input to reset the counter for the next cycle Design and Applied Technology Secondary 4 6 Suggested solution to Question 10 Programmable Logic Controller Jai Ladder diagram Boolean Expression Z A B C D Truth Table A B C D Z 0 0 0 0 0 0 1 0 0 0 1 0 2 0 0 1 0 0 3 0 0 1 1 0 4 0 1 0 0 0 5 0 1 0 1 1 6 0 1 1 0 0 7 0 1 1 1 0 8 1 0 0 0 0 9 1 0 0 1 1 10 1 0 1 0 0 11 1 0 1 1 0 12 1 1 0 0 0 13 1 1 0 1 1 14 1 1 1 0 0 15 1 1 1 1 0 g Design and Applied Technology Secondary 4 6 SECTION 9 REFERENCES 9 1 USEFUL WEB SITES Topics Traffic light control circuit Weblinks http home cogeco ca rpaisley4 20step html Traff 1C Remarks 20 sequential circuits Information and Computer Science http www ics uci edu mghodrat ics151 hw5 prob 8 final html Traffic light Lab Sheet Sequential Circuit Design http www cs swarthmore edu mstone school cs c s24 web lab3 Dynamic Traffic Controller Electrical Training Series http www tpub com content neets 14187 css 1418 7_92 htm Open Loop control O Reilly Network http www oreillynet com pub a
75. s Notes for Theme based Learning Tasks 64 8 Teachers Notes for Assessment Tasks 70 9 References 76 10 Acknowledgements 80 Chapters refer to the Chapters in the Learning Resource Materials of this Module Design and Applied Technology Secondary 4 6 SECTION 1 PRINCIPLES DEVELOPMENT OF LEARNING AND TEACHING MATERIALS This module is composed of four major chapters which include Basics of Control System Pneumatics Programmable Control Systems and Robotics according to the Design and Applied Technology Curriculum and Assessment Guide Secondary 4 6 Based on the total allocated lesson time to DAT is 270 hours not less than 80 hours of which will be dedicated to coursework A rough estimation of time allocated for an optional module such as Automation is about 70 hours Coursework refers to the recommended learning activities included in the Theme based Learning Tasks and Assessment Tasks of the Students Resource Materials The coursework is the essential constituent in the module for students to apply their acquired scientific and technological knowledge to solve authentic problems It involves extensive readings of relevant information and a number of self directed learning outside the classroom Therefore students are expected to have independent learning in addition to the scheduled hours of coursework It is recommended to adopt teaching aids or learning kits to demonstrate concepts in some of the topics suc
76. s one of the subjects in the Key Learning Area of Technology Education therefore hands on and experiential learning activities are the essentials of this subject The theme based learning tasks are the main features of this subject They are also the strategies for catering learners diversity as the learning outcomes of these activities are open to the students ability Talented students can innovate or even invent a new product whilst mediocre or less able students can also make their own technological artifacts under the guidance of teachers and the availability of resources The Stop and Think in the students resources packages can serve as a tool to assess how well students are learning during the lessons formative assessment and as a basis to provoke classroom interaction The Stop and Think is recommended for probing questions to promote learning atmosphere Design and Applied Technology Secondary 4 6 SECTION 2 CONCEPT MAP 1 4 Operation 2 2 Pneumatics Components of traffic lights ey g 1 6 Application and Symbols of control pamena 1 3 Sequential systems Module 3 operation of in a buggy 1 3 sora ah a washing machine 1 7 Application a neee N of control systems in air conditioner Module 4 i 1 4 Logic Circuits 2 3 Understanding Pneumatic Components Module 4 2 1System Electronic 1 10pen loop eseeenon Chapter control systems c sche pice ms 2
77. the following robots a 6 DOF Articulated robot b 6 SCARA i Body and Arm assembly 1 2 ii Wrist assembly 1 2 iii Joint notation scheme 1 2 Figure 4 27 a Articulated robot b SCARA robot Suggested Answer i 1 TRR 2 TTL ji 1 TRR 2 LTR Gii 1 TRR TRR 2 TTL LTR STOP AND THINK 1 What will be the number of mobility DOM and number of freedom DOF for a telescopic arm which has 4 steps of extension DOM DOF What is are the use s of knowing the work envelope for a robot Design and Applied Technology Secondary 4 6 Suggested Answer The study of working envelope is very important to design the safety fence of the work cell and the configuration of the floorplan 1 Why solenoid actuator can only perform duty of light loading 2 Why pneumatic drive system has difficulty of controlling with high accuracy Suggested Answer 1 The core is extracted and retracted by the magnetic force and spring force respectively which in nature will not produce large force Also the longer the core the greater the cantilever effect as the loading is usually acting perpendicular to the axis of the core 2 The compressibility of air makes the pneumatic system not very precise in nature Design and Applied Technology Secondary 4 6 SUGGESTED ANSWERS TO QUIZZES CHAPTER 4 1 What is the limitation of Gantry Robot The
78. tinued operation Once a program has been downloaded to the PLC from the personal computer the personal computer can be disconnected from the PLC The PLC can continue to execute the programmed commands in standalone mode Design and Applied Technology Secondary 4 6 Keeping in mind that the contact X1 the coil Y1 connecting wires and power appearing in the personal computer s display are all virtual They do not physically exist as real electrical components They are just the commands in a computer program It just resembles a real relay schematic diagram that electrical engineers are familiarized with Only the switch closure and lamp status are the real devices The program status is used to command the power to different virtual contacts and coils 8 Modifying the Program Since the PLC is a programmable device we can alter its function by changing the commands in the program without the need to reconfigure the electrical components connected to it For example suppose we wanted to make this switch and lamp circuit function in an inverted fashion We push the button to make the lamp turn off and release it to make it turn on The hardware solution requires a normally closed pushbutton switch to substitute for the normally open switch The software solution becomes relatively easy It just alters the program so that contact X1 is normally closed instead of normally open In the following illustration we have the
79. ts e Applications of robots 14 Understand the use of robots in daily life and industry axes of motion actuator and feedback device and methods of teaching the arm movement and position e g lead by nose teach pendant and off line programming Describe different types of robot arms grouped by their movements and functions e g mechanical movements pick and place welding and spray painting Discuss the advantages and limitations of robots e g social impact accuracy safety repeatability economy and applications Design and Applied Technology Secondary 4 6 SECTION 10 ACKNOWLEDGEMENTS The authors wish to thank the following persons organizations for permission to use their photographs and images Under the GNU Free Documentation License P 73 right upper corner Every effort has been made to trace the copyright for the photographs and images as needed We apologize for any accidental infringement and shall be pleased to come to a suitable arrangement with the rightful owner if such accidental infringement occurs Technology Education Section Developed by Curriculum Development Institute Institute of Professional Education And Education Bureau Knowledge PEAK VTC The Government of the HKSAR
80. umidity When there is fire alarm triggered in practical the security guard will go to the area to make sure the fire is happening and then trigger the break glass B Explain why each sensor has its own IP address In the digital world over thousands of sensors can be connected by a twisted pair cables For the central processing unit to identify the location of specific sensor a unique IP address of each sensor become necessary In practice the IP is manually set by the dip switch in accordance to the system configuration designed by the engineer C Investigate how the intelligent sensors confirm the fire happen The sensor can confirm the fire happening by two parameters one is smoke and the other is temperature rise Smoke is detectable and the temperature rise is also measurable Two measurable parameters function as a logic input to an integrated sensor Integrated sensor means one sensor device can detect both smoke and temperature rise When two inputs are both 1 to the sensor it will function as a decision making logic AND and output an alarm signal Design and Applied Technology Secondary 4 6 D Investigate what other fire extinguish methods to be used besides the sprinkle system Fire shutter and curtain are alternative methods of fire extinguish Fire shutter confine the fire within a closed area until all the oxygen is burnt out and then the fire extinguish naturally Fire curtain
81. xhibition the exhibition venue Website brochure Marketing strategy budgeting and pricing Organize field trip to Promotion and Co organizer of exhibition centre and advertising exhibition and train design office the promoters Design and Applied Technology Secondary 4 6 MODULE 1 AUTOMATION TEACHING SCHEME SAMPLE 2 Chapter 1 Basics Of Control System Aims and Objectives Students will be given an introduction of what is are control or control systems about Students should have the necessary terminology and knowledge in analysis control systems after completion of this chapter Students should be able to understand the following concepts open Loop and closed Loop control timing diagram state output table equilibrium and proportional band With the supplementary notes from the teachers guide more able students can be exposed to the concepts of digital signal processing and PID control which seem to be the fundamental for pursuing further study of control engineering Teaching Strategies 1 Teacher can conduct lecture and provide demonstration to deliver the concepts of control systems as students need to have fundamental knowledge of control theory 2 Teacher should take real life example or artifacts to explain the concepts of control theory For example washing machine air conditioner and buggy can be adopted for demonstration and interactive learning activities Learning Strategies

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