1. Project P12016 Magy Yasin | Dave Taubman | Curt Beard | Oliver Wing | Aalyia Shaukat | Stu Burgess | Jeff Chiappone | Multi-Disciplinary Senior Design 1 Project Manager Lead CE/EE Project Engineer Lead ME/IE Systems-Level Design Review | Oct. 7, 2011

2. Agenda Meeting Goals Project Background o Objectives o Customer Needs o Spec Overview o Team Overview Functional Analysis Concept Development Physical System Architecture o Arriving at this System Risk Assessment Schedule

3. Goals Gain Feedback: positive or negative specific feedback on design Identify Problem Areas: based on feedback, develop a road map of problem areas and how to solve them Discover Ways to Improve: our models, our assumptions, our methods Answer the Question: does our design do what our customer needs? Acknowledge Readiness: to move onto detail design

4. 10/6/11 "Design and Fabricate a Navigation Aid for the Visually Impaired/Blind" Navigates a person from any point on the second floor of the Gleason Building to any other point on the floor Map is based on RFID tags which define rooms and landmarks Utilizes Dijkstra's Routing Algorithm to determine optimal route Device does not rely on auditory cues Does not impair use of cane or guide dog Project Objective

5. Customer Needs Customer Need # ImportanceDescription CN11 Navigates blind person from any location to any other location on a single floor within a building, where destination has a room number. CN21 Navigates efficiently CN31 Operates successfully under conditions that the user is likely to encounter, such as: destination change while en-route, user goes "off the map," user stops using the device while en-route, device fails, ect. CN41 Portable and untethered CN51 Gives non-visual, non-Braille instructions/feedback CN61 Easy to use CN72 Easy to train user CN81 Comfortable and safe to use CN91 Operates for an entire day without recharging CN101 Battery is easy to replace CN112 Doesn't distract the user or others near the device CN122 Doesn’t draw attention to the user CN131 Hands are not needed to carry device CN141 Parts cost < 700 dollars CN152 Navigate blind person to drinking fountain, restroom, or other Important location that may not have a (known) room number CN163 Work independently of system of units (SI vs English)

6. Device Specifications SpecificationUnit of MeasurementIdeal Value SizeInches<= 4x2x1 WeightPounds<= 0.025 System CostDollars< 700 No. of 20-min Navigation Intervals per Charge #>= 10 Charge TimeHours<= 8 Battery Replacement TimeMinutes< 1 Map Read/Load TimeMinutes< 1 Wrong Command Provided to UserFrequency< 1/1000 Commands are Non-VisualY/NYes Distinct and Distinguishable Commands#>= 5 Distinct Inputs From User#>= 4 Verification of User Input ProvidedY/NYes Size of user inputDigits6 Duration Between CommandsSeconds<=2

7. Device Specifications SpecificationUnit of MeasurementIdeal Value Operating Conditions: TemperatureDegrees (Celsius)0-40 Operating Conditions: Relative HumidityPercentage0-100 Noise Generated By Device at 3 ftDecibels< 50 Impact Resistance: Fully Functional After Drop From Set Height Feet3 Hands Required to Carry System#0 Hands Required to Position/Use System#0,1 Attachment Time (by user)Minutes< 1 Removal Time (by user)Minutes< 1 Training Time (1st time)Hours< 1 Wear Time Without DiscomfortHours> 8 Device is UntetheredY/NYes Enclosure TemperatureDegrees (Celsius)< 48.8 Tag Interrogation FrequencySeconds< 1 Minimum Tag Read DistanceFeet4

8. Team Roles Magy YasinISE Project Manager, Ergonomics, Usability/Human Interface, Design of Experiments, Maintenance and Manufacturing Dave TaubmanEE Lead EE/CE, RFID Reader Characterization, RFID Reader Interface to MCU, RFID Antenna Interface Curt BeardEE Impedance matching, Analog-to-Digital and Digital-to-Analog Interface, Drive Circuitry, Device Characterization, Board Layout Oliver WingCE MCU Selection, Programming, Algorithm Implementation, Memory Allocation, MCU Development Board Interface and Usage Aalyia ShaukatEE Voltage and Current sense circuitry, Power Budget Analysis, Battery Selection, Regulation Circuitry, Sensor Interface Circuitry Stu BurgessME Analysis and Design of Enclosure: CAD, Heat Dissipation, Drop Test, Manufacturing Enclosure, Cables & Connectors, User Input Device Selection, Attachment Ergonomics Jeff ChiapponeME Lead ME/IE, Analysis and Design of Tactile Feedback: Dynamics, Power, User Perception of Feedback, Cable Routing

9. Functional Decomposition WhatHow

10. Input Alternatives Trackball-styleClick wheelTouch screen KeypadKnob

11. Input Alternatives – Pros/Cons ProsCons Trackball Less moving parts, higher reliablityToo many “positions”, less intuitive Click wheel Less moving parts, clicks become memorizable Complex design, may require rebuild or reverse engineering Touch screen Out-of-the-box functionality, can be made to order, re-programmable May rely too heavily on “visualization” of gestures,etc. Keypad Out-of-the-box functionality, can be made to order, waterproof, re-programmable Some limit on size Knob Simple to operate, higher reliabilityVery limited on size, less intuitive

12. Feedback Alternatives Electromagnetic Levitation Hobby Servo with Bracket Temperature Linear Actuator Vibrational Motor

13. Feedback Alternatives – Pros/Cons ProsCons Electromagnetic Levitation Incredibly precise feedback, one moving part Tech requires extensive research, parts not readily available, very expensive and labor-intensive Hobby Servo Precise, steady motionLarger, heavier, expensive Vibrational Motor Out-of-the-box functionality, inexpensive, tiny Requires damping to prevent housing from also vibrating Temperature A unique experience, no moving partsMay require steep learning curve Linear Actuator Precision Tend to come in larger sizes, higher weights, expensive

14. Power Supply/Charging What is the easiest way to charge the device? What is the most efficient way to power the device? Charging: o Wall adapter, Solar Cells, Kinetic Motion, USB Powering the Device: o Batteries, Other forms of stored energy

15. Charging – Wall Adapter Pros Dedicated port for charging Not direction specific Quick rate of charging Cons Additional Port needed to charge device. o More holes in casing Need external wall adapter o Easy to misplace, bulky

16. Charging – Solar Cells Pros Would not need any external power bricks Can charge in any location Cons Needs to be sunny outside o Unable to charge at night Expensive to implement Not enough current to power the microcontroller

17. Charging – Kinetic Motion Pros Charge while you move No external power brick needed Can charge in any location Cons Need to be moving to ensure a charge on the device o Difficult to charge Bulky components needed to implement

18. Charging – USB Pros Fast charging Uses existing port on device Simple to implement Can charge with computer or with additional adapter Universal, Inexpensive cable Cons Uni-Directional input Need to be plugged into the wall or computer

19. Powering the Device Must be easily rechargeable Batteries have a large advantage over other forms of power storage. o weight/size to storage density Several different types of batteries available

20. Batteries Available Li-Ion – Lithium Ion (80-90%) o Pros: Small, Light, No memory effect, low self discharge o Cons: High internal resistance, Cell rupture if mishandled Ni-Cd – Nickel Cadmium (70-90%) o Pros: Can be fully discharged, high # Charge cycles o Cons: Expensive, Low energy density, Use of cadmium Ni-MH – Nickel Metal Hydroxide (66%) o Pros: High current drain, low resistance o Cons: High output voltage, low capacity, long charge time

21. RFID Interfaces Skyetek-SkyeModule™ M9 RFID Reader Available Interfaces: o TTL (RS-232) – Requires Host Board o SPI o I²C o USB – Requires Host Board

22. SPI – Serial Peripheral Interface Pros Simple Can achieve high data rates Simpler and more efficient in point to point communication o Lack of device addressing = less overhead Well documented interface libraries Cons No flow control Supports only one master device No hardware slave acknowledgment http://www.eetimes.com/discussion/beginner-s-corner/4023908/Introduction-to-Serial-Peripheral-Interface

23. I²C - Inter-Integrated Circuit Pros Two wire connection Good for >1 Slave device Cons Previous team was unable to successfully implement design. Slaves need a unique address

24. Routing Algorithm

25. System Level Diagram

26. Sensor data The RFID reader can determine which tags are within range, but not their distances The RFID reader has a sleep mode that consumes less than 2% of the active power requirement Data from the compass and the accelerometer can be collected over time to determine a change in position Goal: use the accelerometers and the compass to provide most of the feedback, and use the RFID tags occasionally to verify the location

27. Map representation Major considerations include the size of the map file (limited memory space on the board), the ASCII character set requirement spec, and the 1000 maximum tags spec Maps consist of: o tags, each with an ID (12 bytes) and X and Y coordinates in inches or centimeters (range: 0~4000); o map vertices (e.g., rooms, water fountains, bathrooms, hall intersections), each with X and Y coordinates; o walking paths between vertices, which include the start and end vertices o assumption that the device is currently only being used to navigate one floor of one building

28. Map representation (continued) Possible solution: use base64 notation (ASCII-safe but still small) o Tags, with their large ID fields, will likely comprise the largest part of the file o With base64 notation, tag IDs require 16 'digits' and the coordinates will use 2+2 'digits' = total of 20 bytes per tag o The MCU memory must be able to accommodate up to 1000 tags = 20KB minimum per map (restricts MCU choice!) Store the graph underlying the map of destinations and paths densely (low connectedness)

29. Microcontroller selection Selection: Arduino Nano (weak in clock speed, but sufficient in memory and I/O options, and can start programming quickly) with TI MSP430F5529 as a backup choice

30. Figure 1. Flowchart representing the Dijkstra algorithm. To convert to A*, change the step that selects the vertex with the lowest distance value to instead pick the lowest distance value/heuristic combination.

31. Morph Chart FunctionsOptions Attach to user: location WaistNeckWristArmHandBackHeadLeg/ankle Attach to user: method VelcroBeltWatch bandSpandex/sleeveHeadbandBackpackGlove Send output to userLorentz Mag-LevVibrational motor Pressure wristband Servo spine Combo of vibration & touch Receive user inputKeypadKnob Retro-style telephone dial Touch screenScanner Power all components: charge method Wall adapterSolar cellsUSBKinetic motion Power all components: battery Lithium IonNiCadNiMH MicrocontrollerArduinoPICTI OMAP

32. Pugh Chart Specs and Customer needsSystem ISystem IISystem IIISystem IV Datum Charge time0-0- Non-visual commands0000 Verification of user input provided0000 Hands to carry system0000 Hands to position/use system0000 Attachment time0+++ Removal time0+++ Training time (input)0-++ Tag interrogation freq.0000 Distinct inputs from user---- Noise at 3 ft.-00- Training time (output)-00+ Size+++- Weight+++- Cost+--- Device is untethered++++ Number of 20' nav intervals on full charge+++- Time to read map from electronic source+0++ Wrong command (direction) provided++++ Distinct & distinguishable+00+ Time between commands+00+ Impact resistance++-- Wear time without discomfort+-+- Doesn't draw attention+-+- # of +'s128119N/A # of -'s3539N/A # of 0's81095N/A Total Score9380 N/A System ISystem IISytem IIISytem IVEnd configuration.: KeypadKnobTouchscreenScannerKeypad ArduinoPICTI OMAPArduino Vib. MotorPressure WristbandPressure PointsVib. Motor/Touch ComboVib. Motor Li-IonNiMHLi-IonNiMHLi-Ion AnklebandHeadbandGlove/armNecklaceGlove/Arm/Wrist USB PowerSolar CellWall AdapterKinetic MotionUSB Power

33. Input Decision: Keypad Size: LxWxD: 2” x 1.58” x.5” (smallest) Weight.016 lbs/7.5g (smallest) Manufacturer/Source: Sparkfun Electronics, adafruit.com, futurlec.com, Cost: $3.95 (cheapest) Material: aluminum, plastic, silicone Connection: 7 output pins Meets Requirements: can be programmed to suit, some models come with Arduino microcontroller support, requires only one hand to use Reliability: Low actuation force, waterproof, millions of actuations per life of unit

34. Pre-made vs. Build to Suit: Pre-made keypads: o May allow for design-specific layout, more intuitive to user o May be able to design a smaller keypad than most pre-made models, but: o They may also have long lead times for manufacturers to produce Built to suit keypads: o Require less time incorporating into team’s specific design o Have built-in Arduino support

35. Custom Keypads May Be: Radial Directional Functional and Ergonomic Slim and Compact

36. Custom Keypads Manufacturers: Top Bound USA Baran Miller Dial Gray Hill – *very thin rubber keypads (.2”), also sells individual keys with switches

37. Feedback Decision: Vibrating Motor Size: 0.5” long Weight.004 lbs/2 g (lightest) Manufacturer/Source: Amazon, TrueSupplier, futurlec.com, Cost: $2.99 (cheapest) Material: aluminum, copper, synthetic foam Connection: 2 copper leads Meets Requirements: provides distinguishable output to user, voltage allows for change in intensity, can be placed in multiple locations for diverse feedback communication Reliability: only one moving part, compact, suppliers guarantee millions of revolutions per life of unit

38. Decision - Charging Using USB The user will already have to be familiar with programming the device via USB Existing USB charging controllers are well documented and special IC’s already exist.

39. Decision - Li-ion Battery High capacity Best size to weight ratio Fast charging and long battery life Charge lasts a long time

40. Example USB Li+ Charger Uses existing IC’s to implement and control charge and output voltage o Source: http://www.maxim-ic.com/app-notes/index.mvp/id/3241

41. Decision - SPI Pre-made functions and well documented library by Arduino Simple and easy to use for single Master-Slave configuration Previous team unable to implement I²C successfully

42. Questions?

43. Heat Dissipation Assumptions Housing is a rectangular box with four equal sides Bottom surface is well insulated Uniform air temperature inside housing Uniform temperature gradient on walls Heat generated by all electrical components lumped in to a single Qsource QSide QTop QSide Qsource = 4*Qside + QTop Conduction: Q = (k*A*∆T) / t Convection: Q = (h*A*∆T) Basic Equations

44. Additional Assumption Qsource is floating within the box Heat Dissipation – Initial Analysis Calculations Using a known ambient temperature and known Qsource temperatures can be calculated by analyzing and summing up heat flow through each individual wall Heat transfer through each wall is a simple 2D analysis Convective coefficients will need to be estimated Equations can be put in MatLab to quickly recalculate for different geometry/materials Very conservative and simple analysis If calculated temperatures are excessive a secondary analysis will be done TcompTair,iTwall,iTwall,oTair,o Qsource

45. Heat Dissipation – Secondary Analysis Additional Assumption Qsource is attached to one of the walls Designate sections of wall to only conductive or convective heat transfer Calculations Similar to previous analysis with addition of direct conduction of heat from the components to the wall If temperatures are still found to be excessive will need to consider use of more conductive materials and/or incorporate heat sinks to reduce resistances in the thermal circuit TcompTair,iTwall,i Twall,o Tair,o QsourceQwalls Qcomponent conduction

46. Housing Material MaterialDensity (g/cm3) Elastic Modulus (GPa) Thermal Conductivity (W/(m*K)) Steel7.820052 Aluminum2.769210 Carbon / Epoxy1.6142, 10~1.5 E-Glass / Epoxy2.145, 12~1.5 Polyester1.43~0.2 Results of thermal analysis, drop tests and projected budget will help determine whether to use metals, polymers, composites or a mix of materials

47. Human Factors Interaction between user and product. Quick Response Constraints: to prevent mistakes being made – Input Different sizes and textures Input data twice – Output Feedback should be differentiable. – Device shape: should help determine placement Asymmetrical Shape

48. Adjustability Ensure product is secure – Position – Elastic material Spandex – Adjust product first time to user – Release button Ensure button is not easily pressed.

49. Testing - Types Drop Test (ME) Thermal (ME) Noise (ME) Usability (ISE) Comfort (ISE) Attachment/Detachment (ISE) Training Time (ISE) Software Functionality (CE) Battery (EE) Amount of power used (EE)

50. Testing - User Interface Feedback Capability: Determine distance between vibrational motors – Order feedback parts – Determine minimum distance needed to sense different feedbacks Input Error: Determine input error rate – Collect data on the number input error observed from sample

51. Testing - Methodology Drop Test Obtain sample sheets of possible materials Cut sample to approximate size of one side of housing Attach weight equal to projected weight of device to samples Perform drop tests Thermal Testing Obtain thermocouples and heater capable of outputting power equal to that of the device Place heater inside manufactured housing unit and monitor temperatures until steady state is achieved

52. Testing - Program Unit testing Self-testing (power-on self test) Algorithm correctness Application testing o Cooperation with sensor and feedback interfaces o Testing directional feedback on-site without mechanical parts  Use log files or USB communication to check results o Comprehensive error cases – user input, sensor input, map data

53. Risk Assessment

55. Schedule

56. Schedule Continued

57. Questions?