ECE 477 Final Presentation Group 7  Fall 2005 Tarun Siripurapu Nichole Mattson Colleen Shea Siddharth Sen

Outline Project overviewProject overview Block diagramBlock diagram Professional componentsProfessional components Design componentsDesign components Success criteria demonstrationsSuccess criteria demonstrations Individual contributionsIndividual contributions Project summaryProject summary Questions / discussionQuestions / discussion

Project Overview Pan and tilt camera platformPan and tilt camera platform –2 ° accuracy –+/-180 ° pan and +/- 45° tilt –Absolute and relative motion –Controllable through either a cell phone or keypad –Voice feedback –Image visible via local monitor

Block Diagram

Professional Components Constraint analysis and component selection rationaleConstraint analysis and component selection rationale Patent liability analysisPatent liability analysis Reliability and safety analysisReliability and safety analysis Ethical and environmental impact analysisEthical and environmental impact analysis

Constraint Analysis Microcontroller Motor Selection – –Brushless DC, DC, Stepper – –Stepper chosen for price, accuracy, fixed step size, speed flexibility Position Encoder Options – –Absolute, Relative, Potentiometers User Interface

Constraint Analysis Microcontroller Constraints (initial estimate) – –Motor Control 2 x Pulse Width Modulators (speed) 2 x GPIO (direction) – –Position Feedback 2 x Pulse Accumulators (position) 2 x GPIO (direction) – –Text to Speech Feedback Serial Communications Interface – –User Input 4 x GPIO (12 key, hex encoded) 1 x IRQ

Selection Rationale (9S12C) – –5 x PWM – –8 x TIM / PA – –SCI – –6 x GPIO (8 required) unused module pins can be repurposed as GPIO – –8 x ADC not required in the initial estimate but useful for a backup position feedback system Constraint Analysis Microcontroller Final Usage – –PWM (2) motor speed (2) – –GPIO (6) motor direction (2) user input (4) – –IRQ (1) user input (1) – –ADC (2) motor position (2) – –SCI text to speech (Tx)

Constraint Analysis Motors Constraints – –Must be unipolar – –Run off a 5V (preferred) or 12V power supply – –Small physical dimensions – –High internal resistance to prevent limit current draw – –Between 1º to 5º step size – –Price Selection Rationale (Danaher 12V DC Unipolar Stepper) – –3.6º step size – –Half stepping capability – –Small physical dimensions – –Importance of fine step size – –Added current limiting resistors – –$17/each

Constraint Analysis Position Encoding Constraints – –2º accuracy – –GPIO pins – –Pulse Accumulators – –Speed – –Absolute position detection Selection Rationale (Potentiometers) – –ADC availability – –Ability to detect absolute position – –Linearity – –Faster when compared to pulse accumulation – –Lower I/O pin requirement when compared to 8 bit (required for 2º accuracy) position encoders.

Constraint Analysis User Interface Constraints – –Audio Feedback – –Communication over cell phone network – –Enable the user to input numbers and direction – –Local and Remote control – –Simplicity Selection Rationale – –Audio feedback (text to speech) Dynamic SCI DIP form factor for early testing and debugging. – –DTMF decoder for cell phone communication Maps cell phone keypad to user interface Generic DTMF decoder will suffice – –Keypad encoder for local control Keypad to mimic cell phone keypad

Patent Liability Analysis Potential Patent InfringementsPotential Patent Infringements –Patent 5,633,681: Electrically controlled camera positioning system Claims capacitive sensor assembly and specific packagingClaims capacitive sensor assembly and specific packaging –Patent 6,913,403: Integrated enclosure and controller for video surveillance camera Claims a heating elementClaims a heating element –Patent 6,880,987: Pan and tilt positioning unit (Quickset International) Claims housing, platform, and unique drive systemClaims housing, platform, and unique drive system Most similar to present designMost similar to present design

Reliability/Safety Analysis Acceptable level of failures per hour: less than 10^-5Acceptable level of failures per hour: less than 10^-5 Predicted number of failures per hour: 2.47 X 10^-6Predicted number of failures per hour: 2.47 X 10^-6 Three components analyzedThree components analyzed –Microcontroller MTTF = X 10^6 hoursMTTF = X 10^6 hours –Voltage Regulator MTTF = 8.96 X 10^6 hoursMTTF = 8.96 X 10^6 hours –Motors MTTF = X 10^6 hoursMTTF = X 10^6 hours

Reliability/Safety Analysis FMECAFMECA High CriticalityHigh Criticality –Motor circuit failure (motor, transistor, PLD) –Voltage regulator failure –Micro failure Low CriticalityLow Criticality –DTMF, Keypad failure –TTS failure

Ethical/Environmental Analysis EthicalEthical – Safety Warning labelsWarning labels –Prominent placement –“Do not open or tamper with device.” –“Motors may heat up.” –“Do not touch the gears while they are spinning.” – “In case of emergency call 911 NOT manufacturer!” – Privacy Voice heard both over cell phone and locallyVoice heard both over cell phone and locally

EnvironmentalEnvironmental –Ferric Chloride used to etch PCB’s Alternative: Cut PCB traces mechanicallyAlternative: Cut PCB traces mechanically –Lead Solder –End of Lifetime Disposal: Reuse components if possibleReuse components if possible Incentive provided for returning the device to the manufacturerIncentive provided for returning the device to the manufacturer Ethical/Environmental Analysis

Design Components Packaging design considerationsPackaging design considerations Schematic design considerationsSchematic design considerations PCB layout design considerationsPCB layout design considerations Software design considerationsSoftware design considerations

Packaging Design ConstraintsConstraints –Compact –Sturdy –Range of motion –Easy access of UI devices –Should not block the field of view of the camera or any mounted device.

Packaging Design Platform motion designPlatform motion design Allows ±180° range of motion for panningAllows ±180° range of motion for panning Allows 360Allows 360° range of motion for tilting. Brackets to hold potentiometers stationary during motor motion (not shown).Brackets to hold potentiometers stationary during motor motion (not shown).

Packaging Design 1.Easy keypad access for user input. 2.Easy addition of cell phone to platform. 3.Local and Remote control switch. 4.Attached speaker for local voice feedback.

Schematic Design Power CircuitPower Circuit

Schematic Design Motor CircuitMotor Circuit

Schematic Design Microcontroller CircuitMicrocontroller Circuit

Schematic Design Text to Speech CircuitText to Speech Circuit

Schematic Design User Interface CircuitUser Interface Circuit

PCB Layout Design Design ConsiderationsDesign Considerations Reduce Electromechanical Interference (EMI)Reduce Electromechanical Interference (EMI) –Physically separate analog and digital circuitry –Tie analog and digital grounds together at a single point Trace length, width, and placementTrace length, width, and placement –Length from ICs to decoupling capacitors –40 mils for motor current, VCC, and GND Number of viasNumber of vias Header placementHeader placement –Incorporate debug headers when possible –Place close to side of board

PCB Layout Design

Software Design Mixture of Polling and InterruptMixture of Polling and Interrupt Written in AssemblyWritten in Assembly Modules Used:Modules Used: –ATD –PWM –TIM –SCI

START Infinite Loop to wait for Interrupt Check Validity If Key pressed is “#”, Execute Command Determine which Key has been pressed Interrupt Received Software Design: Program Flow

Start Add 100 values of ATD Readings Compare Current Value with Value Desired If Value is Close Enough, Slow Down If Value is Extremely Close, Stop Motors and wait for next Interrupt Software Design (Execute Command)

main Startup_CodeButton_Pressed PWM_Init TIM_Init SCI_Init ATD_Init Port_Init outchar Execute_Command pmsgx Software Design (Function Hierarchy)

Success Criteria Demonstrations 1.Ability to position the camera platform at a rotation angle ranging from -180 ° to +180 ° and at an elevation angle ranging from -45 ° to +45 °, both within an accuracy of ± 2 ° 2.Ability to position the platform at absolute rotation and elevation angles via a local keypad 3.Ability to control relative movement of the platform via a local keypad 4.Ability to control absolute or relative movement of the platform via a cell phone 5.Ability to provide audio feedback both locally as well as through a cell phone concerning the platform’s status. Video 1 Video 1 Video 2 Video 2

Individual Contributions Team Leader – Tarun SiripurapuTeam Leader – Tarun Siripurapu Team Member 2 – Nichole MattsonTeam Member 2 – Nichole Mattson Team Member 3 – Siddharth SenTeam Member 3 – Siddharth Sen Team Member 4 – Colleen SheaTeam Member 4 – Colleen Shea

Team Leader – Tarun Siripurapu Software DevelopmentSoftware Development Worked on DTMF DecoderWorked on DTMF Decoder Helped with Text to Speech EncoderHelped with Text to Speech Encoder Design Constraints AnalysisDesign Constraints Analysis Packaging DesignPackaging Design PackagingPackaging Feedback CalibrationFeedback Calibration

Member 2 – Nichole Mattson Helped select motors and design motor driverHelped select motors and design motor driver Researched encoder optionsResearched encoder options Schematic DesignSchematic Design Helped with PCB layoutHelped with PCB layout Reliability and Safety AnalysisReliability and Safety Analysis Selected and ordered various componentsSelected and ordered various components Helped with Patent LiabilityHelped with Patent Liability Populated PCBPopulated PCB CAD drawingCAD drawing

Member 3 – Siddharth Sen Software DevelopmentSoftware Development PackagingPackaging Worked on Text to Speech EncoderWorked on Text to Speech Encoder Helped with DTMF DecoderHelped with DTMF Decoder Software DebuggingSoftware Debugging Ethical / Environmental AnalysisEthical / Environmental Analysis Software DesignSoftware Design Feedback CalibrationFeedback Calibration

Member 4 – Colleen Shea PCB component placement and layoutPCB component placement and layout Helped with ORCAD schematic designHelped with ORCAD schematic design Populated PCBPopulated PCB Developed motor driver and associated circuitryDeveloped motor driver and associated circuitry Motor circuit debuggingMotor circuit debugging Selected and ordered componentsSelected and ordered components Patent Liability AnalysisPatent Liability Analysis

Project Summary Important lessons learnedImportant lessons learned –Component selection Thorough documentationThorough documentation There are some things they don’t teach you to look for (DC resistance of inductor)There are some things they don’t teach you to look for (DC resistance of inductor) Notice specific part numbers and packageNotice specific part numbers and package –Hire an ME to do packaging –You can never have enough headers –Specialize

Project Summary Second iteration enhancementsSecond iteration enhancements –Higher torque motors –Cover exposed gears –Battery powered –Add a microphone to enable two-way communication –Remotely switch between cell phone and keypad

Questions / Discussion