A L L A N , A N D R E W , B E N , D A N , J U S T I N E , & M A R I S A

P15044DETAILED DESIGN REVIEW

ENGINEERING SPECIFICATIONS

rqmt. # Importance Source Function Engr. Requirement (metric) Unit of MeasureMinimum

ValueTarget Value

Maximum Value

S1 3 C1 Detection Differentiates between obstacles, overhangs, and walls yes/no yes

S2 3 C1 Detection Response time seconds 0 0.25 1

S3 3 C1 Detection Percentage of false negatives/positives (accuracy of detection) % 0 5 10

S4 3 C2 Detection Detects drop offs in front of the cane through a swept arc yes/no yesS5 3 C3 Detection Start of detection range (distance from the tip of the cane) feet 6 7 13

S6 3 C3 Detection Detection angle/arc (at maximum length) degrees (°) 2 3 3

S7 3 C4 Feedback Percentage of feedback correctly interpreted by user % 80 90 100

S8 3 C5 Fabrication Materials cost $ 0 125 125

S9 2 C6 Use User assembly time seconds 30 60 90

S10 2 C7 Fabrication Maximum weight of feedback and detection components ounces 4 4 16

S11 2 C8 Battery Battery life hours 8 8 /

S12 2 C9 Dimensions Cane length (when in use) centimeters 129 134 139

S13 2 C9 Dimensions Cane handle circumference centimeters 10.8 11.4 12

S14 1 C10 Battery Battery recharge cycle hours 2 2 3

S15 1 C11 Storage Cane length (when collapsed) inches 0 13 15

S16 1 C11 Storage Cane width (when collapsed) inches 0 8 8

S17 3 C2 Detection Dropoff Height height 1 6 7

S18 3 C2 Detection Dropoff Length size(") 12 12 14

S19 3 C2 Detection Dropoff Range range 6 7 13

S20 3 C1/C2 Detection Compensate for user sweep heights height 0 6 12

S21 3 C1/C2 Detection Compensate for user sweep angles angle 30 60 120

S22 2 C9 Use Operating Temperature (°C) 25 30 35

S23 3 C4 Use Feedback Intensity intensity(g) 0.2 ?? 3

S24 3 C4 Use Feedback Frequency frequency (Hz) 20 200 500

S25 2 C8 Detection Detect Battery Life tolerance (hr) 0.25 0.25 0.5

SUB-FUNCTION REQUIREMENT MAPPING

SubfunctionRqmt

# Engineering Requirement Provide Feedback

Detect Overhangs Detect Objects Detects

DropoffsProcess

DetectionPower Cane

Assemble Cane

S1 Differentiates between obstacles, overhangs, and walls   X X X X    S2 Response time X X X X X    

S3Percentage of false negatives/positives (accuracy of detection)   X    

S4Detects drop offs in front of the cane through a swept arc   X      

S5 Detection range (length)   X X X      S6 Detection angle/arc (at maximum length)   X X      S7 Percentage of feedback correctly interpreted by user X        S8 Materials cost X X X X X X  S9 User assembly time             X

S10Maximum weight of feedback and detection components X X X X X X X

S11 Battery life       X  S12 Cane length (when in use)         XS13 Cane handle circumference         XS14 Battery recharge cycle       X  S15 Cane length (when collapsed)         XS16 Cane width (when collapsed)         XS17 Dropoff Height   X X    S18 Dropoff Length   X      S19 Dropoff Range   X      S20 Compensate for user sweep heights   X X    S21 Compensate for user sweep angles   X X    S22 Operating Temperature X   X XS23 Feedback Intensity X        S24 Feedback Frequency X        S25 Detect Battery Life X   X X  

SUBSYSTEM DECOMPOSITION

FEEDBACK DECOMPOSITION

DETECTION DECOMPOSITION

ULTRASONIC TRANSDUCER TEST RESULTS

Risk Risk Mitigation ResultsMaximum 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.

ULTRASONIC TRANSDUCER TEST PLAN

Risk # Risk Description Likelihood

Severity

Weight Mitigation Plan

1 Maximum sensor distance too low.

2 3 5 Test each sensor for max distance, change sensor if specs aren't met

2 Sensor deadzone is too large 1 1 1 Test each sensor for deadzone, change sensor if specs aren't met

3 Low sensor accuracy 2 2 5 Test each sensor for accuracy, change sensor if specs aren't met

4 Sensors are too expensive 3 2 9 Review customer requirements with customer. Either the prototype cost threshold will increase or detection

requirements will be loosened.5 Slow sensor response time 1 2 4 Check datasheets of each sensor6 Too wide sensor beam angle 2 2 6 Test each sensor for beam angle, change sensor if

specs aren't met7 Sensor draws too much

power1 2 3 Check 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 Addressed1,2,3

ULTRASONIC TRANSDUCER TEST PLAN

Test Function

Test Procedure

Sheet Detecti

on

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 Addressed1,2,3

Test Function

Test Procedure

Sheet Detectio

n

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 Addressed3,6

ULTRASONIC TESTINGDetecting 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.

ADDITIONAL MB1010 TESTING

Beam Angle Measurements

Trial Number: 1Distance(ft): 2

Angle of Sensor (°) Sensor Readings (V)

Left Right0 0.22 0.225 0.22 0.22

10 0.22 0.2215 0.22 0.2220 0.22 0.2225 0.23 0.2330 0.23 0.2335 2.44 2.4440 2.44 2.4445 2.44 2.4450 2.44 2.4455 2.44 2.4460 2.44 2.44

Maximum Detection Angle

30 30

Beam Angle Sweep 60

SENSOR BEAM PATTERN

Case C

Distance from sensor (in)

Sensor spread length at distance (in)

Length of the hypotenuse (in)

Resolution beam angle (°)

12 6 13.41640786 53.13010235

24 12 26.83281573 53.13010235

42 21 46.95742753 53.13010235

48 24 53.66563146 53.13010235

72 27 76.89603371 41.11209044

96 36 102.5280449 41.11209044

120 27 123 25.36076698

144 6 144.1249458 4.771888061

ULTRASONIC POSITIONING

ULTRASONIC POSITIONING

ResultsAngle of the Bottom Sensor (°)

10.05 9.55 10.98

Angle of the Top Sensor (°)

40.80 42.79 39.46

Parameters

Case (Ideal)

Case (Worst Case

Positive)

Case (Worst Case Negative)

Cane Length (in) 53.15 55.15 51.15Handle Length (in) 7 7 4Enclosure Length (in) 4 4 4Height Above Ground (in) 34.5 37.5 31.5Bottom Sensor (Distance from lowest edge of enclosure) [in] 1 2 1Top Sensor (Distance from lowest edge of enclosure) [in] 2 3 1

INFRARED TRANSDUCER TESTING

Summary of Risks Summary 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.

INFRARED ULTRASONIC TRANSDUCER TEST RESULTS

Risk Risk Mitigation ResultsMaximum 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.

INFRARED TRANSDUCER TEST PLAN

Risk # Risk Description Likelihood

Severity

Weight Mitigation Plan

1 Maximum sensor distance too low.

2 3 5 Test each sensor for max distance, change sensor if specs aren't met

2 Sensor deadzone is too large 1 1 1 Test each sensor for deadzone, change sensor if specs aren't met

3 Low sensor accuracy 2 2 5 Test each sensor for accuracy, change sensor if specs aren't met

4 Sensors are too expensive 3 2 9 Review customer requirements with customer. Either the prototype cost threshold will increase or detection

requirements will be loosened.5 Slow sensor response time 1 2 4 Check datasheets of each sensor6 Too narrow sensor beam

angle2 2 6 Test each sensor for beam angle, change sensor if

specs aren't met7 Sensor draws too much

power1 2 3 Check 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 Addressed1,2,3

INFRARED TRANSDUCER TEST PLAN

Test Function

Test Procedure

Sheet Detecti

on

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 Addressed1,2,3

Test Function

Test Procedure

Sheet Detectio

n

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 Addressed3,6

INFRARED TRANSDUCER TESTINGDistance 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.

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).

IR SENSOR POSITIONING

ResultsAngle of the IR Sensor (°) 17.3474 14.2109 21.1775Maximum Sweep Height (in) 5.7120

5.7480 5.5440

***Angle is with respect to the cane.Worst Case Positive with Ideal Angle

Worst Case Negative with Ideal Angle

Dist B1 [ft] 8.57 5.79Maximum Sweep Height (in) 3.24 8.244

ParametersCase

(Ideal)

Case (Worst Case

Positive)

Case (Worst Case Negative)

Cane Length (in) 53.15 55.15 51.15Sensor Height (ft) 2.44 2.27 2.61Handle Length (in) 7 7 4Sensor Mount Length (ft) 4.10 4.26 3.93Enclosure Length (in) 4 4 4Height Above Ground (in) 34.5 37.5 31.5IR Sensor (Distance from lowest edge of enclosure) [in] 0 0 0Dist B1 [ft] 7 7 7Dropoff height (in) 6 6 6

BATTERY LONGEVITY TESTING

Summary of Risks Summary 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.

BATTERY LONGEVITY TEST PLAN

Battery Testing Circuit

Battery Testing Arduino CodeTest

FunctionTest Procedure

Battery Longevi

ty

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.

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

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

GENERATED DATA

COLLECTED DATA

COLLECTED DATA

COLLECTED DATA

COLLECTED DATA

WEIGHT FEASIBILITY

Component SystemQty

Weight

Ext. Weight

Li+ 18650 Electronics 1 45 45GP2Y0A710K0F Sensor 1 9 9MAX EZ Sonar Sensor 2 4.3 8.6Circuit Components Electronics 1 28 28Wires+Connectors Electronics 1 10 10Feedback Motor Feedback 3 1.5 4.5Enclosure Enclosure 1 50 50

Maximum Weight 450gDesired Weight 140gUsed Weight 155.1gWeight Left (Desired State) -15.1gWeight Left (Maximum State) 294.9g

PRODUCT MODEL

PRODUCT MODEL

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.

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

ENCLOSURE DESIGN

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 21st:• 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

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

ASSEMBLY DRAWING

ASSEMBLY DRAWING

ENCLOSURE BASE

ENCLOSURE BASE

ENCLOSURE BASE

ENCLOSURE COVER

ENCLOSURE LID