P 15044 DETAILED DESIGN REVIEW ALLAN ANDREW BEN

P 15044 DETAILED DESIGN REVIEW ALLAN, ANDREW, BEN, DAN, JUSTINE, &MARISA

ENGINEERING SPECIFICATIONS rqmt. # S 1 S 2 S 3 S 4 S 5 S 6 S 7 S 8 S 9 S 10 S 11 S 12 S 13 S 14 S 15 S 16 S 17 S 18 S 19 S 20 S 21 S 22 S 23 S 24 S 25 Importance Source 3 3 3 3 2 2 2 1 1 1 3 3 3 2 C 1 C 1 C 2 C 3 C 4 C 5 C 6 C 7 C 8 C 9 C 10 C 11 C 2 C 2 C 1/C 2 C 9 C 4 C 8 Function Detection Detection Feedback Fabrication Use Fabrication Battery Dimensions Battery Storage Detection Detection Use Use Detection Engr. Requirement (metric) Differentiates between obstacles, overhangs, and walls Response time Percentage of false negatives/positives (accuracy of detection) Detects drop offs in front of the cane through a swept arc Start of detection range (distance from the tip of the cane) Detection angle/arc (at maximum length) Percentage of feedback correctly interpreted by user Materials cost User assembly time Maximum weight of feedback and detection components Battery life Cane length (when in use) Cane handle circumference Battery recharge cycle Cane length (when collapsed) Cane width (when collapsed) Dropoff Height Dropoff Length Dropoff Range Compensate for user sweep heights Compensate for user sweep angles Operating Temperature Feedback Intensity Feedback Frequency Detect Battery Life Unit of Measure yes/no seconds % yes/no feet degrees (°) % $ seconds ounces hours centimeters hours inches height size(") range height angle (°C) intensity(g) frequency (Hz) tolerance (hr) Minimum Value 0 0 6 2 80 0 30 4 8 129 10. 8 2 0 0 1 12 6 0 30 25 0. 2 20 0. 25 Target Maximum Value yes 0. 25 5 yes 7 3 90 125 60 4 8 134 11. 4 2 13 8 6 12 7 6 60 30 ? ? 200 0. 25 1 10 13 3 100 125 90 16 / 139 12 3 15 8 7 14 13 12 120 35 3 500 0. 5

SUB-FUNCTION REQUIREMENT MAPPING Rqmt Engineering Requirement # S 1 Differentiates between obstacles, overhangs, and walls S 2 Response time Percentage of false negatives/positives (accuracy of S 3 detection) Detects drop offs in front of the cane through a swept S 4 arc S 5 Detection range (length) S 6 Detection angle/arc (at maximum length) S 7 Percentage of feedback correctly interpreted by user S 8 Materials cost S 9 User assembly time Maximum weight of feedback and detection S 10 components S 11 Battery life S 12 Cane length (when in use) S 13 Cane handle circumference S 14 Battery recharge cycle S 15 Cane length (when collapsed) S 16 Cane width (when collapsed) S 17 Dropoff Height S 18 Dropoff Length S 19 Dropoff Range S 20 Compensate for user sweep heights S 21 Compensate for user sweep angles S 22 Operating Temperature S 23 Feedback Intensity S 24 Feedback Frequency S 25 Detect Battery Life Provide Feedback X Detect Overhangs X X Subfunction Detects Detect Objects Dropoffs X X Process Detection X X Power Cane Assemble Cane X X X X X X X X X X X X X X X X X X

SUBSYSTEM DECOMPOSITION

FEEDBACK DECOMPOSITION

DETECTION DECOMPOSITION

ULTRASONIC TRANSDUCER TEST RESULTS Risk Mitigation Maximum sensor distance too low. Perform compliance testing to verify the maximum sensor distance. HC-SR 04 did not meet specifications after compliance testing, MB 1010 exceeded specifications. MB 1010 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. 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. Too wide sensor beam angle Results

ULTRASONIC TRANSDUCER TEST PLAN Risk # Risk Description 1 2 Maximum sensor distance too low. Sensor deadzone is too large 3 Likelihood Severit y 2 3 Weight Mitigation Plan 5 Test each sensor for max distance, change sensor if specs aren't met Test each sensor for deadzone, change sensor if specs aren't met Test each sensor for accuracy, change sensor if specs aren't met Review customer requirements with customer. Either the prototype cost threshold will increase or detection requirements will be loosened. Check datasheets of each sensor Test each sensor for beam angle, change sensor if specs aren't met Check datasheets, reduce amount of pinging/PWM the transmitter, or change sensor. 1 1 1 Low sensor accuracy 2 2 5 4 Sensors are too expensive 3 2 9 5 6 Slow sensor response time Too wide sensor beam angle 1 2 2 2 4 6 7 Sensor draws too much power 1 2 3 Test Function Test Procedure Dowel/Pipe Detection 1. 2. 3. 4. 5. 6. On a level floor, mark off a line that is 16. 5’ long, with 6” markers along the line. At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. Place dowel/pipe 6 ft from front of sensor; making sure the object is directly in front of the sensor. Probe the voltage output of the sensor (AN), and record the measurement. Move the dowel/pipe to the next marker, and record the measurement. Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1, 2, 3

ULTRASONIC TRANSDUCER TEST PLAN Test Function Sheet Detection Test Function Test Procedure 1. 2. 3. 4. 5. 6. On a level floor, mark off a line that is 16. 5’ long, with 6” markers along the line. At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. Place sheet 6 ft from front of sensor; making sure the object is directly in front of the sensor. Probe the voltage output of the sensor (AN), and record the measurement. Move the dowel/pipe to the next marker, and record the measurement. Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1, 2, 3 Test Procedure Sheet Detection 1. 2. 3. 4. 5. 6. 7. 8. 9. Place the sensor on a lazy susan like device that is marked at minimum every 5°. On a level floor, mark off a line that is 16. 5’ long, with 6” markers along the line. At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. Place dowel/pipe 2 ft from front of sensor; making sure the object is directly in front of the sensor. Probe the voltage output of the sensor (AN), and record the measurement. Rotate the sensor 5° counterclockwise from the point at which sensor is mounted, and record the measurement. Repeat Step 6 until measurements have been recorded from 0° to 60°. Repeat Steps 6 -7, however rotate the sensor 5° clockwise. Repeat the whole test with the dowel/pipe 4 ft, 6 ft, 8 ft, and 10 ft from the front of the sensor. Risks Addressed 3, 6

ULTRASONIC TESTING Detecting Pipe-Like Objects HC-SR 04 MB 1010 Summary: • MB 1010 Analog output matches expected outcome (from datasheet) with little error. • HC-SR 04 output does not correlate to the expected outcome from the datasheet.

ADDITIONAL MB 1010 TESTING Beam Angle Measurements Trial Number: 1 Distance(ft): 2 Angle of Sensor (°) 0 5 10 15 20 25 30 35 40 45 50 55 60 Maximum Detection Angle Beam Angle Sweep Sensor Readings (V) Left 0. 22 0. 23 2. 44 Right 0. 22 0. 23 2. 44 30 30 60

SENSOR BEAM PATTERN Case C Distance from Sensor spread length at Length of the Resolution beam sensor (in) distance (in) hypotenuse (in) angle (°) 12 6 13. 41640786 53. 13010235 24 42 48 72 96 120 12 21 24 27 36 27 26. 83281573 46. 95742753 53. 66563146 76. 89603371 102. 5280449 123 53. 13010235 41. 11209044 25. 36076698 144 6 144. 1249458 4. 771888061

ULTRASONIC POSITIONING

ULTRASONIC POSITIONING Parameters Cane Length (in) Handle Length (in) Enclosure Length (in) Height Above Ground (in) Bottom Sensor (Distance from lowest edge of enclosure) [in] Top Sensor (Distance from lowest edge of enclosure) [in] Case (Ideal) Case (Worst Case Positive) Case (Worst Case Negative) 53. 15 7 4 34. 5 55. 15 7 4 37. 5 51. 15 4 4 31. 5 1 2 3 1 9. 55 42. 79 10. 98 39. 46 Results Angle of the Bottom Sensor (°) Angle of the Top Sensor (°) 10. 05 40. 80

INFRARED TRANSDUCER TESTING Summary of Risks • • • 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 Summary of Testing • Two ultrasonic sensors were checked for appropriate specifications and tested for requirement compliance. • The GP 2 Y 0 A 02 YK 0 F and GP 2 Y 0 A 710 YK 0 F are comparable in price and other datasheet specifications • The GP 2 Y 0 A 02 YK 0 F did not provide a suitable range for our requirements, however the GP 2 Y 0 A 710 YK 0 F did meet the specification.

INFRARED ULTRASONIC TRANSDUCER TEST RESULTS Risk Mitigation Results Maximum sensor distance too low. Perform compliance testing to verify the maximum sensor distance. GP 2 Y 0 A 02 YK 0 F did not meet specifications after compliance testing, GP 2 Y 0 A 710 YK 0 F exceeded specifications. GP 2 Y 0 A 710 YK 0 F 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. 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. Too narrow sensor beam angle

INFRARED TRANSDUCER TEST PLAN Risk # Risk Description 1 2 Maximum sensor distance too low. Sensor deadzone is too large 3 Likelihood Severit y 2 3 Weight Mitigation Plan 5 Test each sensor for max distance, change sensor if specs aren't met Test each sensor for deadzone, change sensor if specs aren't met Test each sensor for accuracy, change sensor if specs aren't met Review customer requirements with customer. Either the prototype cost threshold will increase or detection requirements will be loosened. Check datasheets of each sensor Test each sensor for beam angle, change sensor if specs aren't met Check datasheets, reduce amount of pinging/PWM the transmitter, or change sensor. 1 1 1 Low sensor accuracy 2 2 5 4 Sensors are too expensive 3 2 9 5 6 Slow sensor response time Too narrow sensor beam angle 1 2 2 2 4 6 7 Sensor draws too much power 1 2 3 Test Function Test Procedure Dowel/Pipe Detection 1. 2. 3. 4. 5. 6. On a level floor, mark off a line that is 16. 5’ long, with 6” markers along the line. At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. Place dowel/pipe 6 ft from front of sensor; making sure the object is directly in front of the sensor. Probe the voltage output of the sensor (AN), and record the measurement. Move the dowel/pipe to the next marker, and record the measurement. Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1, 2, 3

INFRARED TRANSDUCER TEST PLAN Test Function Sheet Detection Test Function Test Procedure 1. 2. 3. 4. 5. 6. On a level floor, mark off a line that is 16. 5’ long, with 6” markers along the line. At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. Place sheet 6 ft from front of sensor; making sure the object is directly in front of the sensor. Probe the voltage output of the sensor (AN), and record the measurement. Move the dowel/pipe to the next marker, and record the measurement. Repeat Step 5 until measurements have been recorded at all markers. Risks Addressed 1, 2, 3 Test Procedure Sheet Detection 1. 2. 3. 4. 5. 6. 7. 8. 9. Place the sensor on a lazy susan like device that is marked at minimum every 5°. On a level floor, mark off a line that is 16. 5’ long, with 6” markers along the line. At one end of the line, place the fixture the sensor is mounted to either on the floor, or a level table. Place dowel/pipe 2 ft from front of sensor; making sure the object is directly in front of the sensor. Probe the voltage output of the sensor (AN), and record the measurement. Rotate the sensor 5° counterclockwise from the point at which sensor is mounted, and record the measurement. Repeat Step 6 until measurements have been recorded from 0° to 60°. Repeat Steps 6 -7, however rotate the sensor 5° clockwise. Repeat the whole test with the dowel/pipe 4 ft, 6 ft, 8 ft, and 10 ft from the front of the sensor. Risks Addressed 3, 6

INFRARED TRANSDUCER TESTING Distance For Sheet and Pipe-Like Objects GP 2 Y 0 A 02 YK 0 F GP 2 Y 0 A 710 YK 0 F Takeaways: • Range of GP 2 Y 0 A 02 YK 0 F is not sufficient. • Range of GP 2 Y 0 A 710 YK 0 F • is sufficient. • Both sets of results show that IR sensors are not as desirable for object detection due to the nonlinear response.

INFRARED DROPOFF TESTING Summary: • Using the GP 2 Y 0 A 710 YK 0 F 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).

IR SENSOR POSITIONING Parameters Cane Length (in) Sensor Height (ft) Handle Length (in) Sensor Mount Length (ft) Enclosure Length (in) Height Above Ground (in) IR Sensor (Distance from lowest edge of enclosure) [in] Dist B 1 [ft] Dropoff height (in) Case (Ideal) Case (Worst Case Positive) Case (Worst Case Negative) 53. 15 2. 44 7 4. 10 4 34. 5 55. 15 2. 27 7 4. 26 4 37. 5 51. 15 2. 61 4 3. 93 4 31. 5 0 7 6 14. 2109 5. 7480 21. 1775 5. 5440 Results Angle of the IR Sensor (°) Maximum Sweep Height (in) 17. 3474 5. 7120 ***Angle is with respect to the cane. Dist B 1 [ft] Maximum Sweep Height (in) Worst Case Positive with Ideal Angle 8. 57 3. 24 Worst Case Negative with Ideal Angle 5. 79 8. 244

BATTERY LONGEVITY TESTING Summary of Risks • 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. Summary of Testing • Calculations were completed to determine the required number of batteries to power our system. • Two test runs were performed determine the actual m. Ah of the chosen batteries in comparison to the value specified on the datasheet.

BATTERY LONGEVITY TEST PLAN Battery Testing Circuit Battery Testing Arduino Code Test Function Test Procedure Battery Longevity 1. 2. 3. 4. 5. 6. Charge the test battery to 4. 2 V. Program an Arduino Mega using the provided code (Battery Testing Arduino Code). Using the provided schematic (Battery Testing Circuit), wire the components. Use a terminal emulator (such as Pu. TTY 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. 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. Graph the logged values as a function of time to view the voltage characteristic curve.

PROCESSING TEST PLAN

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

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

DETECTION ISR’S

MCU RESOURCE ALLOCATIONS

BATTERY CHARGING

POWER DISTRIBUTION

PROCESSING

SENSORS

VIBRATION

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 =. 25 s • Motor Delay =. 1 s • Response Distance =. 35 s*1 m/s =. 35 m ≈ 1

GENERATED DATA

COLLECTED DATA

WEIGHT FEASIBILITY Component System Li+ 18650 GP 2 Y 0 A 710 K 0 F MAX EZ Sonar Circuit Components Wires+Connectors Feedback Motor Enclosure Electronics Sensor Electronics Feedback Enclosure Maximum Weight Desired Weight Used Weight Left (Desired State) Weight Left (Maximum State) Ext. Qty Weight 1 1 2 1 1 3 1 450 g 140 g 155. 1 g -15. 1 g 294. 9 g 45 9 4. 3 28 10 1. 5 50 45 9 8. 6 28 10 4. 5 50

PRODUCT MODEL

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

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.

MAIN HANDLE COMPONENTS

ENCLOSURE/CANE MOUNT

ENCLOSURE DESIGN

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

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

PROTOTYPE TEST PLAN

PROJECT BOM/BUDGET

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.

CANE PROTOTYPE COST: INDIVIDUAL

CANE PROTOTYPE COST: FULL SCALE MANUFACTURING

PREDICTED BUDGET: MSD 2

PROJECT PLAN: FINAL WEEKS OF MSD 1

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

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.

LOOKING FORWARD: MSD 2

QUESTIONS

ASSEMBLY DRAWING

ENCLOSURE BASE

ENCLOSURE COVER

ENCLOSURE LID