Direct Tire Pressure Monitoring System using Pressure and
Contents
1. Recalibration must be started manually when tires are changed or re inflated Forgetting to perform this initialization can lead to potentially dangerous false positive or false negative alerts Incorrect calibration by the user such as calibration when one or more tires are under inflated can also cause unreliable operation 7 re Inflation 2008 by Larry Carley The Conceptual Framework INPUT PROCESS OUTPUT Pressure Temperature Reading using PIC LEDs and Microcontroller 7 segment Tire Air Pressure Temperature Checks if the tires Display are under pressure or over pressure Independent Intervening Dependert Variable Variable Variable Figure 1 2 Conceptual Framework Figure 1 2 shows the flow of the direct tire pressure monitoring system The TPMS sensor transmitter module measures the temperature and pressure of the tire After the values are acquired it would be transmitted to the TPMS display receiver module The user would now determine if the tires are over pressured or under pressured Statement of the Problem The main problem of this study is the bond between the tire pressure gauge and the LED Specifically this study seeks to answer the following 1 How will the user recognize if the tire has proper pressure and temperature 2 Can the design acquire and display the tire pressure and temperature 3 What would the system look like for the driver to view the results easier 4 How will the system war2. and the audio loudspeaker which converts electrical voltage variations representing music or speech to mechanical cone vibration and hence vibrates air molecules creating acoustical energy A transducer is useful in transferring energy without using wires It is also helpful in receiving signal from moving object like wheel into another device Newtonian Physics 2005 by Benjamin Crowell Digital pressure gauge A tire pressure gauge is adapted to measure the air pressure of a tire while an extinguisher gauge is adapted to measure the internal pressure of a fire 12 extinguisher Regular pressure gauges include two types i e one without liquid and the other with liquid oil filled A pressure gauge generally consists of a spring element and a measuring or sensor device The primary sensing element of the gauge typically comprises a Bourdon tube that incurs a predictable displacement in response to pressure changes to which it is exposed Pressure gauges can generally be divided into two kinds The first kind is a pen type and the other type has pressure indicator on a scale board The value of pressures can be displayed in either digital or analogue form A digital pressure gauge shown in Figure 1 1 generally involves the application of a microprocessor and a pressure measurement device such as a pressure sensor or load cell coupled with a potentiometer Tire Inflation 2008 by Larry Carley Figure 1 1 Digital Pressu
3. Design The actual design has 6 modules the display module from the prototype design which was modified to accommodate new sensor readings and four new sensor modules one for each of the active tire Also 5 LEDs Tire 1 Tire 2 Tire 3 Tire 4 Spare tire were added to the Display module to indicate what tire is being monitored Tire position of the sensor in the vehicle is critical since the display module uses the tire id to enable the tire s designated LED The positioning of the tires is identified on Figure 2 5 FRONT TIRE 1 TIRE 2 TIRE 4 TIRE 3 Figure 2 5 The spare tire was used as a sample prototype before finalizing List of Components For a more detailed list of components for the Display module and Sensor Module see Table 2 1 and 2 2 33 Software Design for Actual Design The software of the actual design is the same as the prototype development The only distinction of the program is the ID generated by each of the sensor modules and how the display modules identify what tire is being observed Each tire sensor module has a unique tire ID This ID is used by the Display module to know what LED it should enable The sensor module also sends a preamble an 8 bit data to let the display module know that the one sending the data is a tire sensor module After sending the preamble the tire ID is sent and then the pressure reading and the temperature reading follow Th
4. Development For the software the group used C language to program the PIC16F877 and rfPIC12f675 microcontrollers MPLAB IDE v7 60 and the plug in PIC C were used to utilize the C language in our design For the pressure reading the display module multiplies the pressure data the sensor module sent by 14 5 since the MS5401 pressure sensor measures the pressure in bars and not in psi The conditions that were set in the display module sensor to determine if the tire is correctly inflated or is safe to use are the following Pressure difference is not more than ipsi If pressure difference is more then 1psi temperature difference should be at least 10 F If temperature difference is not more than 10 F it enables slow leaking If pressure difference is more than 2psi and temperature difference is not more than 10 F it enables fast leaking LED If pressure is more than 35psi and lower than 28psi it enables Pressure Alert LED Figure 2 4 shows the prototype s system flowchart and how the system operates 31 System Flowchart for Prototype Development Enable TPMS sensor module TPMS sensor module detects pressure of tire TPMS sensor module transmits data TPMS display module recieves and compares data to valid pressure range conditions met Enable LED for designated waming type Figure 2 4 Flowchart for Prototype Software Design Procedure for Actual Design Hardware Design for Actual
5. Since the components needed for the design have a high price the group carried out a prototyping design to ensure that the components will work fine and are compatible with each other Design Implementation Software 1 Brainstorming in how the system works 2 Producing the flow of the system 3 Creating the program to be embedded in the microcontrollers 4 Simulating the program using OshonSoft PICSimulator IDE 5 Verifying the output if it is accurate 6 Making the necessary changes on the program after simulating Design Implementation Hardware 1 Creating the circuit diagram of the system and its connection based on the components datasheet 2 Obtaining the components after verifying that the design of the hardware is running properly using Multisim IDE Some components were bought overseas mostly from Singapore because they are not available in the Philippine market 25 3 Creating the hardware of the system after burning the program in the microcontrollers To ensure that the driver will notice if there is a problem in the vehicle s tires the group decided to use 7 segment displays for the actual reading and LEDs for the parameters If a tire s pressure reading is out of the valid range the LED designated for the tire will blink and a beeping sound is made To determine the design s accuracy and reliability actual testing was done The design s reading was tested against a digital tire pressure gauge to get the percentag
6. alert ON 5 4 psi 26 3 psi 25 9 psi Pressure alert ON 6 5 psi 25 1 psi 24 9 psi Pressure alert ON Table 3 10 Decreasing Pressure For the last testing process decreasing the pressure of the test tire and observing its alerts are done in Table 3 10 Its initial pressure value is also 31 2 psi When the pressure decreases by 2 psi the slow leaking LED will turn on If the difference is more than 2 psi the fast leaking LED will turn on and if the pressure is out of range 28 psi 35 psi the Pressure Alert LED will turn on From these conditions the test conducted displays the expected status 49 Chapter 4 CONCLUSION AND RECOMMENDATION Conclusion Direct tire pressure monitoring system was accomplished with the design presented here The design is very helpful to every driver for it can monitor the pressure of each tire The measured pressure will be shown to the display module for the drivers convenience With this they don t need to stop in the nearest gasoline station just to check if their tires are doing well or stop by and check each tire with a pressure gauge Drivers would have no difficulty in using the system because it is very user friendly and proper labels are implemented for easier understanding The temperature sensors are also added to the design to give the drivers more information of the tire s temperature condition The design provides alerts for the drivers if tire problems occur The color LE
7. fulfillment of the design requirement for the degree in Bachelor of Science Computer Engineering Dr Felicito S Caluyo Dean School of EE ECE CoE ACKNOWLEDGMENT The design team would like to express their gratitude to all those who gave them the opportunity to complete this Design Project their family whose unconditional love and understanding have inspired them their friends who Supported and encouraged them through their advises their Panelists and Chairman Engr Meo Vincent Caya Engr Isagani Villamor Engr Mary Ann Joaquin and Engr Noel Linsangan who have shared their expertise time and guidance to improve the manuscript their Adviser Engr Jocelyn Villaverde who has given them professional advices for the success of this study Most especially the design team would like to express their sincere thanks to the Lord Almighty who has given them the strength to carry on Romnick B Alegonza Michelle Anne L Bocado Marvin Allan L Lu TABLE OF CONTENTS TITLE PAGE APPROVAL SHEET ACKNOWLEDGMENT TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES ABSTRACT Chapter 1 DESIGN BACKGROUND AND INTRODUCTION Research Setting Review of Related Literature and Studies Conceptual Framework Statement of the Problem Objective of the Study Significance of the Study Scope and Delimitation Definition of Terms Chapter 2 METHODOLOGY Research Design Design Procedure for Prototype Development Hardware Design for Proto
8. gauge and the design This is the first tire to be measured and this tire is the one located at the upper left side of the vehicle The result shows that the pressures from trials 1 to 4 are increasing but on trial 5 the pressure decreased Trial Distance Measurement Measurement Difference Percentage from a digital from the Error tire gauge design 1 0 km 31 5 psi 31 9 psi 0 4 1 27 2 8 3 km 34 5 psi 32 6 psi 1 9 5 50 3 11 2 km 33 0 psi 32 6 psi 0 4 1 21 4 13 5 km 32 5 psi 32 6 psi 0 1 0 31 5 14 2 km 32 0 psi 32 6 psi 0 6 1 90 Average 2 04 Table 3 2 Pressure of Tire 2 The next table Table 3 2 is for the second tire to be measured In this table the measurement of pressure was increasing from trial 1 to 4 but has a 44 minor decrease at the last trial Trial Distance Measurement Measurement Difference Percentage from a digital from the Error tire gauge design 1 0 km 33 5 psi 33 7 psi 0 2 0 60 2 8 3 km 34 5 psi 34 4 psi 0 1 0 29 3 11 2 km 35 0 psi 34 8 psi 0 2 0 57 4 13 5 km 35 0 psi 34 8 psi 0 2 0 57 5 14 2 km 34 5 psi 34 4 psi 0 1 0 29 Average 0 46 Table 3 3 Pressure of Tire 3 The pressure measured using a digital tire gauge and the design in Tire 3 corresponds to Table 3 3 This tire is positioned to the lower right side of the car Again the measurements are rising but when the meas
9. of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays Encarta Encyclopedia 2007 15 Placard is a sign or sign like device attached to or hung from a vehicle to indicate information about the operator of a vehicle or the contents of the vehicle or building Encarta Encyclopedia 2007 16 Pressure is the force over an area applied to an object in a direction perpendicular to the surface Encarta Encyclopedia 2007 17 Program is a series of computer instructions that are designed to accomplish a task or achieve a particular result Encarta Encyclopedia 2007 18 Psi Pounds per Square Inch is a unit of pressure or of stress based on avoirdupois units 1 psi 6 894757 kPa pascal Pa is the SI unit of pressure ewtonian Physics 2005 19 Temperature is a physical property of a system that underlies the 22 common notions of hot and cold something that is hotter generally has the greater temperature Encarta Encyclopedia 2007 20 Tire pressure gauge is a pressure gauge used to measure the pressure of tires on a vehicle Encarta Encyclopedia 2007 21 Traction is the power to grip or hold to a surface while moving without slipping Encarta Encyclopedia 2007 22 Transmitter is an electronic device which usually with the aid of an antenna propagates an electromagnetic signal such as radio television or other telecommunications Encarta Ency
10. Direct Tire Pressure Monitoring System using Pressure and Temperature Sensor By Romnick B Alegonza Michelle Anne L Bocado Marvin Allan L Lu A Design Report Submitted to the School of Electrical Engineering Electronics and Communications Engineering and Computer Engineering in Partial Fulfillment of the Requirements for the Degree Bachelor of Science in Computer Engineering Mapua Institute of Technology September 2008 Approval Sheet Mapua Institute of Technology School of EE ECE CoE This is to certify that we have supervised the preparation of and read the design report prepared by Romnick B Alegonza Michelle Anne L Bocado and Marvin Allan L Lu entitled Direct Tire Pressure Monitoring System and that the said report has been submitted for final examination by the Oral Examination Committee Aida Alfaro Jocelyn F Villaverde Reader Design Adviser As members of the Oral Examination Committee we certify that we have examined this design report presented before the committee on September 4 2008 and hereby recommended that it be accepted as fulfillment of the design requirement for the degree in Bachelor of Science in Computer Engineering Meo Vincent C Caya Isagani V Villamor Panel Member 1 Panel Member 2 Mary Ann P Joaquin Panel Member 3 This design report is hereby approved and accepted by the School of Electrical Engineering Electronics and Communications Engineering and Computer Engineering as
11. Ds provide the drivers with an instant visual summation of the entire systems condition If the tire begins to sway from normal parameters the LED color will change and allow the driver to know that a situation might be arising that needs attention If the colour of the LED was to go to red then the driver would be informed that an improper condition was developing that could cause a hazardous or even deadly situation if it isn t quickly taken care of Thus the Direct Tire Pressure Monitoring System can really be a big help to the drivers convenience and safety because of its features 50 Recommendations The design team would like to recommend the following 1 The system would be allied with a car manufacturer In this approach the system would be integrated to the product of the car manufacturer and this will produce income 2 The system would be implemented to any kind of vehicles like multiple wheeled trucks motorcycles and etc 3 The display would be more interactive by replacing the 7 segment screen with colored graphics 4 Additional features can also be added to the system like checking a specific tire s pressure 5 Additional studies can also be conducted if there would be an effect to the balance of the tire if a sensor will be installed 51 BIBLIOGRAPHY University Physics with Modern Physics with Mastering Physics 2004 9th Edition MasteringPhysics Series by Hugh D Young Roger A Freedman The Phys
12. clopedia 2007 23 Threshold is synonymous with entrance Encarta Encyclopedia 2007 23 Chapter 2 METHODOLOGY Research Design The design methodology provides instructions and procedures on how to develop a tire pressure monitoring system At first the group conducted a research on previous projects and designs that have a relation to the proposal From there supplementary information were then gathered from books and internet resources With the data on hand the group was able to conceptualize the system s flow and design of the hardware and software Through a research the group found out that the sensor module must be small enough so that the tire will not be unbalanced With this information available the group began searching for components that are light and compact but can deliver the need This was an essential procedure since the project s objective is to monitor each tire Data Gathering 1 The group read articles and studies regarding safety and maintenance of tires which involves the tire s pressure 2 After considering the factors that can affect the tire pressure and the stability of the wheel the group researched for components that are compact but can still deliver the project requirements 24 3 Selected components were then verified for usability and reliability through surveys done in the internet forums intended for technologically inclined people and through the manufacturers technical support
13. cuit Flowchart for Prototype Software Positioning of Tires Flowchart for whole system Flowchart for Check Tire 1 Flowchart for Check Tire 2 Flowchart for Check Tire 3 Flowchart for Check Tire 4 Flowchart for Check Spare Tire 20 20 37 37 38 38 39 39 40 41 42 ABSTRACT Incorrect tire inflation and high tire surface temperatures are hazards to the safety to all those traveling the highways To combat this problem the design team built a system that will monitor the pressure and temperature of an automobile tire All measurements will be taken by battery powered sensors attached directly to the tire and then transmitted by digital signal to a receiver a short distance away inside the wheel well This accommodates the use of four tires in the system The data will then be interpreted by a microcontroller and displayed on LEDs and 7 segment display in such a way the driver can easily identify problems with his or her tire system Ease of use and understanding will create a system that will minimize some of the possible dangers drivers face on the road each day regarding flat tires or over pressured tires Keywords Tire Pressure Safety Flat tire Over pressured tire Chapter 1 DIRECT TIRE PRESSURE MONITORING SYSTEM BACKGROUND AND INTRODUCTION Research Setting Tires are among the most important features on a vehicle However proper tire maintenance is an important safety function that is often neglected The importa
14. e error Design Testing 1 After creating implementing the design the group installed the system in a vehicle See Appendix E for Installation Guide 2 The design was then tested against a digital tire pressure gauge to check for system reliability and integrity Detailed discussion is included in Chapter 3 Design Procedure for Prototype Development Hardware Design for Prototype Development For the prototype development two modules we built the display module which shows the pressure reading and warning for the tire and the sensor module which was placed inside the tire s interior Both modules were packed 26 inside a small metal container so that the components will not be flattened when installed For the readings a 3 digit 7 segment was used LEDs are used to indicate the reading being displayed and for the warnings Components for the prototype are listed on Table 2 1 and Table 2 2 Table 2 1 registers what is used in the Display module while Table 2 2 shows the components for the Sensor module List of Components Quantity Component Description 1 PIC16F877 Microcontroller 5 LED Display 1 3 digit 7 segment display Display 1 RFRXD0420 I LQ RF receiver 1 TC4422 MOSFET Driver 1 RF Antenna Antenna 1 SF0434BA02507S SAW Filter Table 2 1 Display Module components Quantity Component Description 1 MS507 Pressure sensor 1 LM75 Temperature sensor 1 rfPIC12F675F M
15. e is available here in the country After collecting all the necessary components the group made the software for the design The group used MPLAB IDE to program the microcontrollers To test the program without having to embed the software in the microcontrollers the group used OshonSoft PICSimulator The frequency used for transmitting the data is 434 MHz ASK To get this frequency the crystal that was attached to the rfpic s pin 5 see Appendix D for pin configurations is 13 52 MHz which is available in the Philippine market For the prototype development the design was installed in a vehicle to test and to confirm that the prototype is working properly Since the prototype s 41 design consists of only one tire sensor module it was installed on the upper left wheel position and the display module tapped on the accessories jack of the vehicle The wiring for the RF receiver antenna was tied to the vehicles chassis to avoid tangling with the tires The antenna is positioned in the wheel chamber so that the RF signal will not go through many obstructions The power supply of the display module is connected on the vehicle s accessories connection Power is acquired from the vehicle s battery 42 Chapter 3 TESTING PRESENTATION AND INTERPRETATION OF DATA The testing of the design is composed of 2 parts the first part was done on August 28 2008 between 3 30 pm to 6 20 pm The design team started the route from Mapua Inst
16. e system s flowchart is presented in Figure 2 6 It shows how the actual design operates 34 System Flowchart for Actual Design START Vehicle Started Initialize Display Module Wake Up Sensor Modules Check Tire 3 Check Tire 4 Check Tire 1 Check Tire 2 Check Spare Tire Enable LED for designated tire and warning type Pressure values are valid and conditions met Figure 2 6 Flowchart for whole system 35 Set Preamble 0611100001 Tire ID 0b11110001 LEGEND TIRE SENSOR PROCESS Check pressure and temperature i DISPLAY MODULE PROCESS of tire Send Preamble Tire ID pressure reading and temperature reading Preamble 0b11100001 Save readings to designated variables Display temperature reading Enable LED for Tire 1 Display pressure reading Figure 2 7 Flowchart for Check tire 1 Figure 2 7 illustrates how Tire sensor 1 is operating within the tire and how it passes the data It also shows how Display module reads the data submitted and how it interprets it 36 Set Preamble 0611100001 Tire ID 0b11110010 LEGEND fy TIRE SENSOR PROCESS Check pressure and temperature fa DISPLAY MODULE PROCESS of tire Send Preamble Tire ID pressure reading and temperature reading Preamble 0b11100001 Save readings to designated variables Display temperature reading Enable LED for Tire 2 Display pressu
17. ed from electromagnetic forces between atoms and electrons and so it cannot be calculated from first principles but instead must be found empirically Mewtonian Physics 2005 Glycerine is a chemical compound also commonly called glycerin or glycerol It is a colorless odorless viscous liquid that is widely used in pharmaceutical formulations Encarta Encyclopedia 2007 Hardware is a general term that refers to the physical artifacts of a technology Encarta Encyclopedia 2007 Insinuation is synonymous with implication Encarta Encyclopedia 2007 10 LED Light Emitting Diode is a semiconductor diode that emits light when an electrical current is applied in the forward direction of the device as in the simple LED circuit Encarta Encyclopedia 2007 11 MHz MegaHertz is the basic unit of frequency in the International System of Units SI and is used worldwide in both general purpose and scientific contexts Encarta Encyclopedia 2007 12 Microcontroller is a functional computer system on a chip It contains a 21 processor core memory and programmable input output peripherals Encarta Encyclopedia 2007 13 Sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument Encarta Encyclopedia 2007 14 Seven segment_ display abbreviation 7 seg ment display less commonly known as a seven segment indicator is a form
18. erprets it 39 Set Preamble 0b11100001 Tire ID 0b11110101 LEGEND TIRE SENSOR PROCESS Check pressure and temperature i DISPLAY MODULE PROCESS of tire Send Preamble Tire ID pressure reading and temperature reading Preamble 0b11100001 Save readings to designated variables Display temperature reading Enable LED for Spare tire Display pressure reading Figure 2 11 Flowchart for Check Spare Tire Figure 2 11 exhibits how the spare tire sensor is working within the tire and how it passes the data It also shows how Display module reads the data submitted and how it interprets it 40 PROTOTYPE DEVELOPMENT Finding the components was the first thing the group did The rfpic12f675f and the RFRXD0420 I LQ were ordered online The group decided to use the RFPIC microcontroller for the tire sensor modules since it already has an attached RF transmitter Using this microcontroller will make the design compact since it does not need another device Second the rfPIC12F675 also has an internal comparator which plays a vital role in decoding the information from the LF link Lastly the rfPIC12F675 features a 10 bit Analog to Digital converter allowing the group to use analog output pressure sensors For the temperature and pressure sensor one of the group members went to Singapore because delivery of items will take a long time if bought online The microcontroller used for the display modul
19. fers to oscillations in electric circuits or electromagnetic radiation Low frequency is a type of radio frequency The name itself sounds disadvantageous because it can only transmit from a short distance One of the useful applications of low frequency is receiving signal from a certain area Low frequency signal can avoid interfering with other signals Vibration and Waves 2005 by Benjamin Crowell Thermistor A thermistor is a type of resistor with resistance varying according to its temperature The word is a portmanteau of thermal and resistor Thermistors are widely used as inrush current limiters temperature sensors self resetting over current protectors and self regulating heating elements Thermistor is also applicable in measuring the temperature of the tire of a car A small sized thermistor would be appropriate in the tire Electricity and Magnetism 2005 by Benjamin Crowell Review of Related Studies The design is about tire pressure monitoring using sensors to obtain data to be transmitted to the microcontroller The same technology is applied in the indirect tire pressure monitoring system but instead of detecting pressure of the tire by using pressure sensor the radius of the wheel is the basis if the tire is in 15 proper condition Indirect Tire Pressure Monitoring System Indirect acting TPMS measures the apparent air pressure indirectly by monitoring individual wheel rotational speeds and other si
20. gnals available outside the tire itself Most indirect TPMS use the fact that an under inflated tire has a slightly smaller diameter than a correctly inflated tire and therefore has to rotate at a higher angular velocity to cover the same distance as a correctly inflated tire Such TPMS cannot detect under inflation in all four tires simultaneously since if all four tires lose the same amount of air the relative change will be zero In the US the TREAD Act prevents the use of any TPM system which cannot simultaneously detect under inflation of any or all four tires Newer developments of indirect TPMS can also detect simultaneous under inflation in all four tires Thanks to vibration analysis of individual wheels or analysis of load shift effects during acceleration and or cornering however additional sensors add to the complexity and cost of this technology A hybrid method requires adding one direct TPMS sensor to a single tire on a vehicle thereby eliminating the four equally low tires scenario Indirect TPMS is cheap and easy to implement since most modern vehicles 16 already have wheel speed sensors for anti lock braking system and electronic stability control system Another advantage of this technology is that no maintenance of the TPMS is necessary A disadvantage of an indirect system compared to direct is also the periodic requirement for recalibration creating unsafe windows where low tire detection is unavailable
21. icrocontroller RF transmitter Table 2 2 Sensor Module components 27 Circuit Diagrams OLZEebsae aun seq QueuBes 4T TP E ano ManesTtIeu wouy EJEA WSEXD aly ansad bass be NNN WSEXOD Bumyesjqsey AL ZY A ae WSEXDD Bupyesjmojs AL ZY WSEXDO Bulpesy sinssaig AL Ze bos A a T WSEXDD Suipess anzesadwa L Hb zY 849T91Id e22vrvoL ee 70 o EA weexog weds LEH M S lL wSEXOI ban Wee Ea i el A ygexoaea tb ed cd NWA WSEXDI ZNL AL EY x gt AANT woexoo pen hEN Figure 2 1 Display Module Circuit User Interface Figure 2 1 illustrates the circuit for the prototype s Display module The components are listed on Table 2 1 28 RE tm aii w F2 pF R2 S900 10 7 MHz 1 cie RI 10n Cis 3 09F Fi SFO434BA02507S SAW Filter WOU ease GND Ouaput DEE 26 45125 MHz 4 u 7 Figure 2 2 Display Module Circuit RF Receiver Circuit Figure 2 2 is the illustration of the RF receiver module The antenna should be located in the wheel mounted to ensure data integrity 29 oa pand o pan A Ur door 13 Figure 2 3 Tire Sensor Module Circuit Figure 2 3 is the circuit for the Tire Sensor modules Detailed component list is found in Table 2 2 30 Software Design for Prototype
22. ics Factbook An Encyclopedia of Scientific Essays 2007 by Brian Marino Tire Inflation 2008 by Larry Carley Vibration and Waves 2005 by Benjamin Crowell Newtonian Physics 2005 by Benjamin Crowell Electricity and Magnetism 2005 by Benjamin Crowell 52
23. itute of Technology to Cavite and back to the Institute The second part was done when the vehicle is at rest and the design team observes the output of the design Testing Procedure for Part 1 1 Measure the pressure and temperature of each tire starting from Tire 1 Tire 2 Tire 3 and Tire 4 using the design 2 Measure the pressure of each tire using the digital tire gauge 3 Using the odometer measure the distance travelled by the vehicle and reset it for the next measurement 4 The vehicle will have a pit stop and steps 1 to 3 will be repeated until 5 pit stops have been completed Testing Process for Part 2 1 Measure the initial tire pressure using the design 2 Using a digital tire gauge measure the tire pressure for comparison 3 Inflate or deflate the tire with 1 psi up to 5 psi 4 Jot down the results and observe the output for each interval 43 Here are the following data gathered during the testing process Part 1 Pressure Trial Distance Measurement Measurement Difference Percentage from a digital from the Error tire gauge design 1 0 km 32 5 psi 32 6 psi 0 1 0 31 2 8 3 km 33 5 psi 33 0 psi 0 5 1 49 3 11 2 km 33 5 psi 33 4 psi 0 1 0 30 4 13 5 km 34 0 psi 33 4 psi 0 6 1 76 5 14 2 km 32 5 psi 33 0 psi 0 5 1 54 Average 1 08 Table 3 1 Pressure of Tire 1 Table 3 1 is the tabulated representation of the measurement of pressure using a digital tire
24. molecular size and intermolecular attractions the ideal gas law is most accurate for monoatomic gases at high temperatures and low pressures The neglect of molecular size becomes less important for larger volumes i e for lower pressures The relative importance of intermolecular attractions diminishes with increasing thermal kinetic energy i e with increasing temperatures More sophisticated equations of state such as the van der Waals equation allow deviations from ideality caused by molecular size and intermolecular forces to be taken into account Newtonian Physics 2005 by Benjamin Crowell Air Pressure Temperature Fluctuations The air pressure inside the tires supports the weight of the car Maintaining sufficient air pressure is required if tires are to provide all of the handling traction and durability of which they are capable The tire pressure recommended in a vehicle s owner s manual or tire information placard is the vehicle s recommended cold tire inflation pressure This means that it should be checked in the morning before driving it more than 10 a few miles or before rising ambient temperatures or the sun s radiant heat affects it Since air is a gas it expands when heated and contracts when cooled The rule of thumb is for every 10 Fahrenheit change in air temperature tire s inflation pressure will change by about 1 psi up with higher temperatures and down with lower Tire Inflation 2008 by Larr
25. n the user if there are some tire problems Objective of the Study The Direct Tire Monitoring System has the following objectives 1 Inform the driver on recognizing if his her vehicle has correct tire pressure and temperature 2 Acquire correct pressure and temperature of the tire to be displayed on the system 3 Create a user friendly display of pressure and temperature 4 Provide an alert which will inform the driver that he she has tire problems Significance of the Design The Direct Tire Pressure Monitoring System is a new innovation for improving vehicle safety particularly with tire pressure The system is very helpful in avoiding accidents caused by having a flat tire Drivers could easily determine their vehicle s tire pressures With this they don t need to stop in the nearest gasoline station just to check their tires or stop by and check each tire with a pressure gauge Properly maintained tires help with vehicle safety performance and economy Scope and Delimitation The Direct Tire Pressure Monitoring System has the following scopes 1 The design is composed of five modules which are the 4 TPMS sensor transmitter module and a TPMS display receiver module 2 LEDs are provided for easier reading and each LED corresponds to the tires and alerts 3 In order for the design to operate the vehicle must be on 4 The design will check the pressure and temperature of each tire every 30 seconds 5 The 7 segment display
26. nce of properly maintaining the tires cannot be overemphasized Tires are the only contact between the vehicle and the road The tire s pressure if not checked would be risky and dangerous but checking it every time would be a hassle With this insinuation the group comes to a decision of constructing a system inside a car which monitors the pressure of the tire whether it is in proper condition or not Review of Related Literature Ideal Gas Law The Ideal gas law is the equation of state of a hypothetical ideal gas first stated by Benoit Paul Emile Clapeyron in 1834 The state of an amount of gas is determined by its pressure volume and temperature according to the equation PV nRT where P is the absolute pressure of the gas V is the volume of the gas n is the number of moles of gas R is the universal gas constant T is the absolute temperature The value of the ideal gas constant amp is found to be as follows R 8 314472 J mol tK 8 314472 m Pa K tmol t 8 314472 kPa L mol Kt 0 08205746 L atm K mol 62 36367 L mmHg K mol 10 73159 ft psi R Ib mol 53 34 ftlbf R Ibm for air The ideal gas law mathematically follows a_ statistical mechanical treatment of primitive identical particles point particles without internal structure which do not interact but exchange momentum and hence kinetic energy in elastic collisions Since it neglects both
27. re reading Figure 2 8 Flowchart for Check tire 2 Figure 2 8 demonstrates how Tire sensor 2 is working within the tire and how it passes the data It also shows how Display module reads the data submitted and how it interprets it 37 Set Preamble 0611100001 Tire ID 0b11110011 LEGEND fy TIRE SENSOR PROCESS Check pressure and temperature fa DISPLAY MODULE PROCESS of tire Send Preamble Tire ID pressure reading and temperature reading Preamble 0b11100001 Save readings to designated variables Display temperature reading Enable LED for Tire 3 Display pressure reading Figure 2 9 Flowchart for Check tire 3 Figure 2 9 displays how Tire sensor 3 is working within the tire and how it passes the data It also shows how Display module reads the data submitted and how it interprets it 38 Set Preamble 0611100001 Tire ID 0b11110100 LEGEND TIRE SENSOR PROCESS Check pressure and temperature i DISPLAY MODULE PROCESS of tire Send Preamble Tire ID pressure reading and temperature reading Preamble 0b11100001 Save readings to designated variables Display temperature reading Enable LED for Tire 4 Display pressure reading Figure 2 10 Flowchart for Check tire 4 Figure 2 10 demonstrates how Tire sensor 4 is working within the tire and how it passes the data It also shows how Display module reads the data submitted and how it int
28. re Gauge Antenna An antenna is a transducer designed to transmit or receive electromagnetic waves In other words antennas convert electromagnetic waves into electrical currents and vice versa Antennas are used in systems such as radio and television broadcasting point to point radio communication wireless LAN radar and space exploration Antennas usually work in air or outer space but can also be operated under water or even through soil and rock at certain frequencies for short distances Physically an antenna is an arrangement of conductors that generate a radiating electromagnetic field in response to an applied alternating voltage and the associated alternating electric current or can be placed in an electromagnetic field so that the field will induce an alternating current in the antenna and a voltage between its terminals Antenna becomes popular because of its wireless receiving capabilities This technology is suitable in tire pressure monitoring because it can receive Signal even in a rotating wheel 7he Physics Factbook An Encyclopedia of Scientific Essays 2007 by Brian Marino Low Frequency Radio frequency RF is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz This range corresponds to frequency of alternating current electric signals used to produce and detect radio waves Since most of this range is beyond the vibration rate that most mechanical systems can respond to RF usually re
29. sult Actual Result x 100 Actual Result Average PError 1 PError 2 PError 3 PError 4 PError 5 5 Average Percentage Error 1 08 2 04 0 46 1 54 1 28 4 Percentage of Reliability 100 1 28 98 72 So we can conclude that the design is 98 72 reliable according to the data gathered and the testing done Part 2 Trial Applied Test tire using Test tire using Display Pressure the design at a digital tire 43 C gauge at 43 C 1 initial 31 2 psi 31 2 psi 31 4 psi Alerts OFF 2 1 psi 32 5 psi 32 3 psi Alerts OFF 3 2 psi 33 2 psi 33 4 psi Alerts OFF 4 3 psi 34 2 psi 34 5 psi Alerts OFF 5 4 psi 34 9 psi 35 0 psi Alerts OFF 6 5 psi 35 6 psi 35 8 psi Pressure alert ON Table 3 9 Increasing Pressure Table 3 9 represents the measured temperature on Tire 1 which serves as a test tire The initial pressure in it is 31 2 psi and it is inflated up to 5 trials to test if the alerts displayed are correct When the pressure reached 35 the Pressure Alert LED turned ON because the measured pressure is already out of range 48 Trial Applied Test tire using Test tire using Display Pressure the design at a digital tire 43 C gauge at 43 C 1 initial 31 2 psi 31 2 psi 31 4 psi Alerts OFF 2 1 psi 29 1 psi 29 3 psi Alerts OFF 3 2 psi 28 2 psi 28 0 psi Slow Leaking ON 4 3 psi 27 5 psi 27 2 psi Pressure
30. surement from the design 1 0 km 41 C 2 8 3 km 42 C 3 11 2 km 44 C 4 13 5 km 47 C 5 14 2 km 44 C Table 3 7 Temperature of Tire 3 Table 3 7 is provided for the temperature reading in Tire 3 and like in the other readings the temperature decreased in the last trial Trial Distance Measurement from the design 1 0 km 41 C 2 8 3 km 43 C 3 11 2 km 45 C 4 13 5 km 45 C 5 14 2 km 42 C Table 3 8 Temperature of Tire 4 The last tire to be measured is Tire 4 and its temperature measurement according to the design is on Table 3 8 From the data gathered it shows that the pressure and temperature increase from trial 1 to trial 4 but decrease on the last trial A reason for the decrease in pressure and temperature is because the pressure is directly proportional with the temperature according to the Ideal Law of Gasses and the design team arrived at the last pit stop at 6 20 PM so the environmental temperature is much colder compared to the last 4 pit stops A possibility for the slight fluctuation in the reading can be caused by the digital tire gauge As the tire is measured using the tire gauge a small amount of pressure comes out of the tire Then the design team also computes for the percentage error and the computation for the average percentage error resulted to a 1 28 47 Here is the computation for the percentage error and reliability Percentage Error Measured re
31. type Development Software Design for Prototype Development System Flowchart for Prototype Development Design Procedure for Actual Design Hardware Design for Actual Design Software Design for Actual Design System Flowchart for Actual Design Prototype Development vi vi vii 10 11 11 12 13 17 19 19 24 25 26 26 25 27 34 Chapter 3 TESTING PRESENTATION AND INTERPRETATION OF DATA Chapter 4 CONCLUSIONS AND RECOMMENDATIONS Conclusions Recommendations BIBLIOGRAPHY APPENDICES Appendix A Design Codes Appendix B Design Pictures Appendix C User Manual Appendix D Installation Guide Appendix E Project Cost Appendix F Datasheets 36 43 44 45 46 68 71 73 76 Table 2 1 Table 2 2 Table 3 1 Table 3 2 Table 3 3 Table 3 4 Table 3 5 Table 3 6 Table 3 7 Table 3 8 Table 3 9 Table 3 10 Figure 1 1 Figure 1 2 Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 2 5 Figure 2 6 Figure 2 7 Figure 2 8 Figure 2 9 Figure 2 10 Figure 2 11 LIST OF TABLES Display Module components Sensor Module components Pressure of Tire 1 Pressure of Tire 2 Pressure of Tire 3 Pressure of Tire 4 Temperature of Tire 1 Temperature of Tire 2 Temperature of Tire 3 Temperature of Tire 4 Increasing Pressure Decreasing Pressure LIST OF FIGURES Digital Pressure Gauge Conceptual Framework Display Module Circuit User Interface Display Module Circuit RF Receiver Circuit Tire Sensor Module Cir
32. urement for the last trial has been made the pressure was reduced Trial Distance Measurement Measurement Difference Percentage from a digital from the Error tire gauge design 1 0 km 32 5 psi 33 0 psi 0 5 1 53 2 8 3 km 33 0 psi 33 7 psi 0 7 2 12 3 11 2 km 35 0 psi 34 4 psi 0 6 1 71 4 13 5 km 34 5 psi 34 1 psi 0 4 1 15 5 14 2 km 33 0 psi 33 4 psi 0 4 1 21 Average 1 54 Table 3 4 Pressure of Tire 4 Lastly Table 3 4 is for the measurement of pressure for Tire 4 which is the last tire to be measured The outcome of this table is almost the same on Table 3 1 to 3 4 because the pressure on the first 4 trials was increasing but the last trial was decreased 45 Temperature Trial Distance Measurement from the design 1 0 km 46 C 2 8 3 km 45 C 3 11 2 km 47 C 4 13 5 km 49 C 5 14 2 km 47 C Table 3 5 Temperature of Tire 1 Table 3 5 shows the temperature measured by the design on the Tire 1 Its temperature will also be the first one to be measured Trial Distance Measurement from the design 1 0 km 44 C 2 8 3 km 45 C 3 11 2 km 47 C 4 13 5 km 50 C 5 14 2 km 48 C Table 3 6 Temperature of Tire 2 After that the temperature to be considered will be for Tire 2 and it is presented on Table 3 6 along with its corresponding distance Trial Distance Mea
33. will output the temperature and pressure 6 The reading will be considered as under inflated if the pressure is below 28 psi and over inflated if above 35 psi 7 After the reading the system will auto activate its sleep mode The following are the limitations of the design 1 The design is only applicable to 4 wheel vehicles weighing 4 500 kg 2 The design is not applicable to motorcycles and trucks 3 The design is not portable which can be easily transferred to other cars 4 The user cannot select the only tire he she wanted to check 5 The checking of the pressure of each tire is continuous and it cannot be stopped Definition of terms 1 Ambient is outside air temperature Encarta Encyclopedia 2007 2 Apparent is appearing real or true based on evidence that may not be valid Encarta Encyclopedia 2007 3 Bourdon tube is a pressure sensing element constructed from a flattened tube sealed at one end twisted or curved Newtonian Physics 2005 4 Cold inflation pressure is the inflation pressure of tires before the car is driven and the tires warmed up ewtonian Physics 2005 5 Frequency is a measure of the number of occurrences of a repeating event per unit time Encarta Encyclopedia 2007 20 Friction is the force resisting the relative motion of two surfaces in contact or a surface in contact with a fluid e g air on an aircraft or water in a pipe It is not a fundamental force as it is deriv
34. y Carley Environmental Factor In most parts of North America the difference between average summer and winter temperatures is about 50 Fahrenheit which results in a potential loss of about 5 psi as winter temperatures set in Meanwhile in normal weather the sun also affects the temperature of the tires If the vehicle is parked in the sun the sun s radiant heat will artificially and temporarily increase tire pressures Tire Inflation 2008 by Larry Carley Recommended Tire Pressure Many people neglect a very important aspects of the car its tires which are as important as cars are The tires on a car rotate on the ground without slipping creating a driving force due to the friction between the tire and the ground One thing that is important for proper driving conditions is proper tire inflation and pressure The ideal range of pressure in cars is between 193 234 in kPa kilopascal or 28 to 35 psi pounds per square inch Tire Inflation 2008 by Larry Carley Transducer A transducer is a device usually electrical electronic electro mechanical electromagnetic photonic or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer for example pressure sensors The term transducer is commonly used in two senses the sensor used to detect a parameter in one form and report it in another usually an electrical or digital signal
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