1. ALLAN, ANDREW,BEN, DAN, JUSTINE, &MARISA P15044 DETAILED DESIGN REVIEW

2. ENGINEERING SPECIFICATIONS rqmt. #ImportanceSourceFunction Engr. Requirement (metric)Unit of Measure Minimum Value Target Value Maximum Value S13C1DetectionDifferentiates between obstacles, overhangs, and wallsyes/noyes S23C1DetectionResponse timeseconds00.251 S33C1DetectionPercentage of false negatives/positives (accuracy of detection)%0510 S43C2DetectionDetects drop offs in front of the cane through a swept arcyes/noyes S53C3DetectionStart of detection range (distance from the tip of the cane)feet6713 S63C3DetectionDetection angle/arc (at maximum length) degrees ( ° ) 233 S73C4FeedbackPercentage of feedback correctly interpreted by user%8090100 S83C5FabricationMaterials cost$0125 S92C6UseUser assembly timeseconds306090 S102C7FabricationMaximum weight of feedback and detection componentsounces4416 S112C8BatteryBattery lifehours88/ S122C9DimensionsCane length (when in use)centimeters129134139 S132C9DimensionsCane handle circumferencecentimeters10.811.412 S141C10BatteryBattery recharge cyclehours223 S151C11StorageCane length (when collapsed)inches01315 S161C11StorageCane width (when collapsed)inches088 S173C2DetectionDropoff Heightheight167 S183C2DetectionDropoff Lengthsize(")12 14 S193C2DetectionDropoff Rangerange6713 S203C1/C2DetectionCompensate for user sweep heightsheight0612 S213C1/C2DetectionCompensate for user sweep anglesangle3060120 S222C9UseOperating Temperature ( ° C) 253035 S233C4UseFeedback Intensityintensity(g)0.2??3 S243C4UseFeedback Frequencyfrequency (Hz)20200500 S252C8DetectionDetect Battery Lifetolerance (hr)0.25 0.5

3. SUB-FUNCTION REQUIREMENT MAPPING Subfunction Rqmt # Engineering Requirement Provide Feedback Detect Overhangs Detect Objects Detects Dropoffs Process Detection Power Cane Assemble Cane S1Differentiates between obstacles, overhangs, and walls XXXX S2Response time XXXXX S3 Percentage of false negatives/positives (accuracy of detection) X S4 Detects drop offs in front of the cane through a swept arc X S5Detection range (length) XXX S6Detection angle/arc (at maximum length) XX S7Percentage of feedback correctly interpreted by user X S8Materials cost XXXXXX S9User assembly time X S10 Maximum weight of feedback and detection components XXXXXXX S11Battery life X S12Cane length (when in use) X S13Cane handle circumference X S14Battery recharge cycle X S15Cane length (when collapsed) X S16Cane width (when collapsed) X S17Dropoff Height XX S18Dropoff Length X S19Dropoff Range X S20Compensate for user sweep heights XX S21Compensate for user sweep angles XX S22Operating Temperature X XX S23Feedback Intensity X S24Feedback Frequency X S25Detect Battery Life X XX

4. SUBSYSTEM DECOMPOSITION

5. FEEDBACK DECOMPOSITION

6. DETECTION DECOMPOSITION

7. ULTRASONIC TRANSDUCER TEST RESULTS RiskRisk MitigationResults Maximum sensor distance too low. Perform compliance testing to verify the maximum sensor distance. HC-SR04 did not meet specifications after compliance testing, MB1010 exceeded specifications. MB1010 selected. Sensor deadzone is too large Analytically determine minimum deadzone for sensors to perform under desired conditions. Determined that the deadzone was acceptable (matches the Engineering Requirement for the start of the detection range). Low sensor accuracy Perform multiple test trials and verify results with datasheet specifications. Measure the variances of the data. Average variance for dowel detection is 0.9997 (in comparison to 1 ), and average variance for sheet detection is 0.9988 ( in comparison to 1 ). Slow sensor response time Determine analytically maximum time between sensor detection and haptic feedback. Maximum time between detection and feedback was determined to be insignificant in comparison to average human reaction time of 250 milliseconds. Too wide sensor beam angle Perform compliance testing to verify the sensor beam angle. Determine analytically if the angle satisfies the deadzone requirement. Verified that the sensor beam angle was appropriate for use with the deadzone specified by the Engineering Requirements.

8. ULTRASONIC TRANSDUCER TEST PLAN Risk # Risk DescriptionLikelihoodSeverityWeightMitigation Plan 1 Maximum sensor distance too low. 235 Test each sensor for max distance, change sensor if specs aren't met 2 Sensor deadzone is too large111 Test each sensor for deadzone, change sensor if specs aren't met 3 Low sensor accuracy225 Test each sensor for accuracy, change sensor if specs aren't met 4 Sensors are too expensive329 Review customer requirements with customer. Either the prototype cost threshold will increase or detection requirements will be loosened. 5 Slow sensor response time124Check datasheets of each sensor 6 Too wide sensor beam angle226 Test each sensor for beam angle, change sensor if specs aren't met 7Sensor draws too much power123Check datasheets, reduce amount of pinging/PWM the transmitter, or change sensor. Test Function Test Procedure Dowel/Pipe Detection 1.On a level floor, mark off a line that is 16.5’ long, with 6” markers along the line. 2.At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. 3.Place dowel/pipe 6ft from front of sensor; making sure the object is directly in front of the sensor. 4.Probe the voltage output of the sensor (AN), and record the measurement. 5.Move the dowel/pipe to the next marker, and record the measurement. 6.Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1,2,3

9. ULTRASONIC TRANSDUCER TEST PLAN Test Function Test Procedure Sheet Detection 1.On a level floor, mark off a line that is 16.5’ long, with 6” markers along the line. 2.At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. 3.Place sheet 6ft from front of sensor; making sure the object is directly in front of the sensor. 4.Probe the voltage output of the sensor (AN), and record the measurement. 5.Move the dowel/pipe to the next marker, and record the measurement. 6.Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1,2,3 Test FunctionTest Procedure Sheet Detection 1.Place the sensor on a lazy susan like device that is marked at minimum every 5°. 2.On a level floor, mark off a line that is 16.5’ long, with 6” markers along the line. 3.At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. 4.Place dowel/pipe 2ft from front of sensor; making sure the object is directly in front of the sensor. 5.Probe the voltage output of the sensor (AN), and record the measurement. 6.Rotate the sensor 5° counterclockwise from the point at which sensor is mounted, and record the measurement. 7.Repeat Step 6 until measurements have been recorded from 0° to 60°. 8.Repeat Steps 6-7, however rotate the sensor 5° clockwise. 9.Repeat the whole test with the dowel/pipe 4ft, 6ft, 8ft, and 10ft from the front of the sensor. Risks Addressed 3,6

10. ULTRASONIC TESTING Detecting Pipe-Like Objects HC-SR04 MB1010 Summary: MB1010 Analog output matches expected outcome (from datasheet) with little error. HC-SR04 output does not correlate to the expected outcome from the datasheet.

11. ADDITIONAL MB1010 TESTING Beam Angle Measurements Trial Number:1 Distance(ft):2 Angle of Sensor ( ° ) Sensor Readings (V) LeftRight 00.22 5 100.22 150.22 200.22 250.23 300.23 352.44 402.44 452.44 502.44 552.44 602.44 Maximum Detection Angle 30 Beam Angle Sweep60

12. SENSOR BEAM PATTERN Case C Distance from sensor (in) Sensor spread length at distance (in) Length of the hypotenuse (in) Resolution beam angle (°) 12613.4164078653.13010235 241226.8328157353.13010235 422146.9574275353.13010235 482453.6656314653.13010235 722776.8960337141.11209044 9636102.528044941.11209044 1202712325.36076698 1446144.12494584.771888061

13. ULTRASONIC POSITIONING

14. Results Angle of the Bottom Sensor (°) 10.059.5510.98 Angle of the Top Sensor (°) 40.8042.7939.46 Parameters Case (Ideal) Case (Worst Case Positive) Case (Worst Case Negative) Cane Length (in) 53.1555.1551.15 Handle Length (in) 774 Enclosure Length (in) 444 Height Above Ground (in) 34.537.531.5 Bottom Sensor (Distance from lowest edge of enclosure) [in] 121 Top Sensor (Distance from lowest edge of enclosure) [in] 231

15. INFRARED TRANSDUCER TESTING Summary of RisksSummary of Testing Risks can be categorized in two ways: risks that can be addressed through transducer specifications, and risks that can be addressed through compliance testing. Specification Risks: Sensor draws too much power Sensors are too expensive Sensor response time is too slow Testing Risks: Maximum distance of object is not far enough from sensor Sensor deadzone is too large Sensor is not accurate Sensor beam angle is not appropriate Two ultrasonic sensors were checked for appropriate specifications and tested for requirement compliance. The GP2Y0A02YK0F and GP2Y0A710YK0F are comparable in price and other datasheet specifications The GP2Y0A02YK0F did not provide a suitable range for our requirements, however the GP2Y0A710YK0F did meet the specification.

16. INFRARED ULTRASONIC TRANSDUCER TEST RESULTS RiskRisk MitigationResults Maximum sensor distance too low. Perform compliance testing to verify the maximum sensor distance. GP2Y0A02YK0F did not meet specifications after compliance testing, GP2Y0A710YK0F exceeded specifications. GP2Y0A710YK0F selected. Sensor deadzone is too large Analytically determine minimum deadzone for sensors to perform under desired conditions. Determined that the deadzone was acceptable (matches the Engineering Requirement for the start of the detection range). Low sensor accuracy Perform multiple test trials and verify results with datasheet specifications. Measure the variances of the data. Average variance for dowel detection is 0.9997 (in comparison to 1 ), and average variance for sheet detection is 0.8659 ( in comparison to 1 ). Slow sensor response time Determine analytically maximum time between sensor detection and haptic feedback. Maximum time between detection and feedback was determined to be insignificant in comparison to human reaction time. Too narrow sensor beam angle Perform compliance testing to verify the sensor beam angle. Determine analytically if the angle satisfies the deadzone requirement. Verified that the sensor beam angle was appropriate for use with the deadzone specified by the Engineering Requirements.

17. INFRARED TRANSDUCER TEST PLAN Risk # Risk DescriptionLikelihoodSeverityWeightMitigation Plan 1 Maximum sensor distance too low. 235 Test each sensor for max distance, change sensor if specs aren't met 2 Sensor deadzone is too large111 Test each sensor for deadzone, change sensor if specs aren't met 3 Low sensor accuracy225 Test each sensor for accuracy, change sensor if specs aren't met 4 Sensors are too expensive329 Review customer requirements with customer. Either the prototype cost threshold will increase or detection requirements will be loosened. 5 Slow sensor response time124Check datasheets of each sensor 6 Too narrow sensor beam angle 226 Test each sensor for beam angle, change sensor if specs aren't met 7Sensor draws too much power123Check datasheets, reduce amount of pinging/PWM the transmitter, or change sensor. Test Function Test Procedure Dowel/Pipe Detection 1.On a level floor, mark off a line that is 16.5’ long, with 6” markers along the line. 2.At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. 3.Place dowel/pipe 6ft from front of sensor; making sure the object is directly in front of the sensor. 4.Probe the voltage output of the sensor (AN), and record the measurement. 5.Move the dowel/pipe to the next marker, and record the measurement. 6.Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1,2,3

18. INFRARED TRANSDUCER TEST PLAN Test Function Test Procedure Sheet Detection 1.On a level floor, mark off a line that is 16.5’ long, with 6” markers along the line. 2.At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. 3.Place sheet 6ft from front of sensor; making sure the object is directly in front of the sensor. 4.Probe the voltage output of the sensor (AN), and record the measurement. 5.Move the dowel/pipe to the next marker, and record the measurement. 6.Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1,2,3 Test FunctionTest Procedure Sheet Detection 1.Place the sensor on a lazy susan like device that is marked at minimum every 5°. 2.On a level floor, mark off a line that is 16.5’ long, with 6” markers along the line. 3.At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. 4.Place dowel/pipe 2ft from front of sensor; making sure the object is directly in front of the sensor. 5.Probe the voltage output of the sensor (AN), and record the measurement. 6.Rotate the sensor 5° counterclockwise from the point at which sensor is mounted, and record the measurement. 7.Repeat Step 6 until measurements have been recorded from 0° to 60°. 8.Repeat Steps 6-7, however rotate the sensor 5° clockwise. 9.Repeat the whole test with the dowel/pipe 4ft, 6ft, 8ft, and 10ft from the front of the sensor. Risks Addressed 3,6

19. INFRARED TRANSDUCER TESTING Distance For Sheet and Pipe-Like Objects GP2Y0A02YK0F GP2Y0A710YK0F Takeaways: Range of GP2Y0A02YK0F is not sufficient. Range of GP2Y0A710YK0F is sufficient. Both sets of results show that IR sensors are not as desirable for object detection due to the non-linear response.

20. INFRARED DROPOFF TESTING Summary: Using the GP2Y0A710YK0F sensor, dropoffs can be detected by a microprocessor as a sharp decrease in voltage (as seen by the nulls in the data on the right).

21. IR SENSOR POSITIONING Results Angle of the IR Sensor (°) 17.3474 14.210921.1775 Maximum Sweep Height (in) 5.7120 5.74805.5440 ***Angle is with respect to the cane. Worst Case Positive with Ideal Angle Worst Case Negative with Ideal Angle Dist B1 [ft] 8.575.79 Maximum Sweep Height (in) 3.248.244 Parameters Case (Ideal) Case (Worst Case Positive) Case (Worst Case Negative) Cane Length (in) 53.1555.1551.15 Sensor Height (ft) 2.442.272.61 Handle Length (in) 774 Sensor Mount Length (ft) 4.104.263.93 Enclosure Length (in) 444 Height Above Ground (in) 34.537.531.5 IR Sensor (Distance from lowest edge of enclosure) [in] 000 Dist B1 [ft] 777 Dropoff height (in) 666

22. BATTERY LONGEVITY TESTING Summary of RisksSummary of Testing The only risk associated with batteries is that the batteries chosen do not provide enough power to run the system for the required maximum operation time. Calculations were completed to determine the required number of batteries to power our system. Two test runs were performed determine the actual mAh of the chosen batteries in comparison to the value specified on the datasheet.

23. BATTERY LONGEVITY TEST PLAN Battery Testing Circuit Battery Testing Arduino Code Test Function Test Procedure Battery Longevity 1.Charge the test battery to 4.2V. 2.Program an Arduino Mega using the provided code (Battery Testing Arduino Code). 3.Using the provided schematic (Battery Testing Circuit), wire the components. 4.Use a terminal emulator (such as PuTTY or Tera Term) to monitor the COM port of the Arduino, which will TX the ADC readings on digital pin 1. Setup a log file to keep the results in, and timestamp them. 5.Keep track of the battery starting voltage, ending voltage, start time, and end time. When the COM port first starts reading 613, the battery has reached the minimum voltage, and the test is concluded. 6.Graph the logged values as a function of time to view the voltage characteristic curve.

24. PROCESSING TEST PLAN

25. MAIN PROGRAM LOGIC Setup: Initializes The Interrupt Services Sets default settings values Loop: Checks the various program state flags Handles outputs accordingly

26. FUNCTIONS Low Power Handler: Indicates Low Power to User Goes into deep sleep mode Detection Handler: Turns the corresponding indication motor on or off Settings Handler: Indicates new vibration intensity Returns to previous state

27. DETECTION ISR’S

28. MCU RESOURCE ALLOCATIONS

29. BATTERY CHARGING

30. POWER DISTRIBUTION

31. PROCESSING

32. SENSORS

33. VIBRATION

34. DROP OFF DETECTION Algorithm testing via Matlab Simulation Two Stages: Data Created based off assumptions Data Collected from actual use Collected Data was not as noisy as expected which makes filtering considerably easier Alleviates processing power risks Detection Delay =.25s Motor Delay =.1s Response Distance =.35s*1m/s =.35m ≈ 1

35. GENERATED DATA

36. COLLECTED DATA

40. WEIGHT FEASIBILITY Component SystemQtyWeightExt. Weight Li+ 18650 Electronics145 GP2Y0A710K0F Sensor199 MAX EZ Sonar Sensor24.38.6 Circuit Components Electronics128 Wires+Connectors Electronics110 Feedback Motor Feedback31.54.5 Enclosure 150 Maximum Weight 450g Desired Weight 140g Used Weight 155.1g Weight Left (Desired State) -15.1g Weight Left (Maximum State) 294.9g

41. PRODUCT MODEL

43. HANDLE DESIGN The handle will be 3D printed in four individual parts, which will be shown in detail, and assembled to create the final system.

44. MAIN HANDLE COMPONENTS The main handle contains the motors (hidden in this view), the battery (light blue), and the USB interface (purple) which will allow the user to charge the cane.

45. MAIN HANDLE COMPONENTS

46. ENCLOSURE/CANE MOUNT

47. ENCLOSURE DESIGN

50. HANDLE TEST RESULTS Prototype handles revealed that proposed motor mounting system is valid. Longevity testing revealed that motors can run for extended periods with negligible changes in heat, and no changes in power requirements. Motor response time confirmed to be 50 ms (average). To be addressed on Friday, November 21 st : Ability to differentiate between motor locations Ability to differentiate between vibrational intensity

51. PROTOTYPE TEST PLAN 3 prototype handles will be created, each with different motor locations, as shown in the diagrams below: Users will be asked to indicate which motor configuration is more clear in terms of response, as well as to indicate the ability to differentiate between intensity levels

52. PROTOTYPE TEST PLAN

53. PROJECT BOM/BUDGET

54. PROJECT BOM/BUDGET CON’T Based on the Updated Risk Plan going forward into MSD 2, it was determined that 60% of the budget needs to be saved for use in MSD 2.

55. CANE PROTOTYPE COST: INDIVIDUAL

56. CANE PROTOTYPE COST: FULL SCALE MANUFACTURING

57. PREDICTED BUDGET: MSD 2

58. PROJECT PLAN: FINAL WEEKS OF MSD 1

60. MANAGERIAL LESSONS LEARNED Ensure that entire team is involved with developing potential risk scenarios Involve guide more throughout the design process in order to save time when it comes closer to presentation time Base budgeting decisions on possible material replacements, rather than allocating entire budget to separate portions of the design

61. ENGINEERING LESSONS LEARNED Verify concept analytically before component selection. Initial IR sensor range was not adequate for dropoff detection. Test multiple solutions to engineering problems to verify which is the most effective. Often, initial assumptions are not the most effective. Don’t overlook tools required to perform tests. Second IR sensor did not come with a cable.

62. LOOKING FORWARD: MSD 2

63. QUESTIONS

64. ASSEMBLY DRAWING

67. ENCLOSURE BASE

70. ENCLOSURE COVER

71. ENCLOSURE LID