Smart CaneIEEE Design Presentation

Lauren Bell, Jessica Davila, Jake Luckman, William McIntyre, Aaron Vogel

Introductions

• Lauren Bell – Mechanical Engineer• Jessica Davila – Industrial Engineer• Jake Luckman – Mechanical Engineer• William McIntyre – Electrical Engineer• Aaron Vogel – Mechanical Engineer

Agenda• Problem Description• Design Challenge• Potential Concepts• Critical Design Decisions• Final Concept• System Operation• Testing and Traceability• Project Management• Conclusion• Acknowledgements

Problem DescriptionSafe and easy navigation in the world is difficult for the blind and

deaf/blind

InexpensiveIntuitive

ExpensiveTraining Required

Limited Situation Feedback

Excellent Situation Feedback

COMMON SOLUTIONS

Project Goal

Design Challenge……To design, fabricate, assemble and validate a ‘haptic handle’

• To be attached to a traditional cane• Provide directional feedback to blind and deaf/blind users

Process Overview

Concept Selection

• Many ideas to one

Design Considerations

• Defining the engineering requirements & constraints

Generation of Final Design

• Integration of all subsystems

Testing of Prototype

• Trace back to engineering requirements

Potential Concepts

• Track Ball• Piston Push Feedback• Torque ‘Jerk’• Scroll Navigation• Magnetic Force Feedback

Brainstorming and benchmarking yielded the following likely candidates…

Narrowing Our SelectionCustomer

requirementsVibration

MotorsTrack Ball

NavigationPiston Push Feedback Torque ‘Jerk’ Scroll Navigation Magnetic Force

Feedback

Easy to Feel Direction Datum + + + + +

Provides Directional Feedback

Datum + + + + S

Safe to use Datum S S S S S

Compact Design Datum - S S S S

Lightweight Datum - - - S S

Affordable within our

budgetDatum S S S S S

Fast Response time Datum S S S S S

Easy for users to learn within our

time frameDatum S S S S S

Able to be used with gloves Datum + + + + +

Scroll Navigation

Pros• Easier to feel direction• Better directional feedback• Can be used with gloves

Cons• May inhibit index finger

haptic ability

Screw-in cap

Battery Housing

Microcontroller

Continuous servo

Scroll Transmission

Mock Ups• Final Concept Ideas• Finger Bump Scroll• Palm Bump Roller

• Final Concept Selection• Palm Roller

Design Considerations

Customer desire Technical Requirement

Light weight < 1 lbs.

Customer desires needed to be transformed into technical requirements…

Design Considerations

• Pressure on System• Bump Characteristics• Stress• Motor • Power Management• Microcontroller

Design Grip Pressure Spec • Ensure handle functions under excessive grip• Measure pressure of displaced air for rough idea• Median pressure ~3 psi

• Compare to Grip Pressure Study*• FSR sensors on glove• “Crush grip” measured on 50mm diameter handle• 5 male and 5 female adults• Maximum pressure ~3.1 psi

Tao Guo qiang; Li Jun yuan; Jiang Xian feng, "Research on virtual testing of hand pressure distribution for handle grasp," Mechatronic Science, Electric Engineering and Computer (MEC), 2011 International Conference on, pp.1610,1613, 19-22 Aug. 201

Design made to withstand at least 3 psi.

Bump Characteristics Analysis

ComfortSensitivity

Through testing, effective bump height and speed was determined.

Motor Requirements

• Maximum moment occurs when:• Grip reaches maximum design pressure• Pressure force is perpendicular to contact point• Palm contact area is maximum on roller• Two rollers contact the palm

• Maximum moment caused by worst case scenario design pressure• 50.1 oz-in

Selected motor met all design requirements.

Roller Analysis• Bumps per rotation• Servo to Roller Spacing• Effectiveness of our

model – Audience?

Roller and Pins Force/Stress Analysis

Rollers and pins withstand force and stress under worst case

scenarios.

Signal Flow Diagram

Micro Family SelectionArduino MSP430

Price $20-100 $3-15

Architecture 8 Bit RISC 16 Bit RISC

Clock Speed 8-16 MHz 8-25 MHz

Stand Alone Capability No Yes

Maskable Interrupt Lines 2 2

Power 165mW .5mW

Simulation and Detection System

Final Concept

System Operation

Micro controller sends information to PCB

PCB controls motor

Motor turns roller sub assembly• Battery supports total system

Rollers rotate beneath user’s palm indicating the direction to move in

System has passed all tests

Testing and Traceability

Prototype meets all non-technical requirements

Testing and Traceability

Risk Assessment ID Risk Item Likelihood Severity Importance

1 Burning out micro controller 3 2 6

2 Software is ineffective 2 3 6

3 Haptic handle and testing systems integration issues 2 3 6

4 Not meeting customer expectations 2 3 6

5 Not obtaining parts on time 2 2 4

6 Battery malfunction 2 2 4

7 Over budget 2 2 4

8 5 volunteers for user test are not established in time 2 2 4

9 Cane does not stay together, durability failure 1 3 3

10 Not completing software component 1 3 3

11 Haptic forces not being strong enough 1 3 3

12 Hardware and software integration 1 3 3

13 Detection is ineffective 1 3 3

14 Team Member leaves team 1 3 3

15 Cane gets dropped repeatedly on the ground 1 3 3

16 Excessive tapping 1 3 3

17 Handle material is not effective (Tears with consistent wear) 1 3 3

18 Uncoordinated team schedules 1 2 2

19 Selected power and components produce excessive heat 1 2 2

20 Necessary facilities and personnel are not available when needed 1 2 2

21 System is too heavy for desired cane weight 1 1 1

Risk Curve

All risks were tracked and managed.

20-Aug 9-Sep 29-Sep 19-Oct 8-Nov 28-Nov 18-Dec 7-Jan 27-Jan 16-Feb 8-Mar 28-Mar 17-Apr 7-May0

10

20

30

40

50

60

70

80

90

Actual Planned

Sum

of R

isks'

Impo

rtan

ce

Project Plan/Work Dispersion

Project plan was tracked and work was properly distributed .

Conclusion• Desired cane handle objective was met

Recommendations

• Complete cane with integration to sensors

• Improve handle to provide feedback on changes in elevation and proximity of obstacles.

Acknowledgements• Guides• Gary Werth• Gerry Garavuso

• Customers• Dr. Patricia Iglesias• Gary Behm• Tom Oh

• Professor Mark Indovina• Jeff Lonneville

Attractive/Repulsive Magnetism Navigation

Pros• Easier to feel direction• Better directional

feedback• Can be used with gloves

Cons• Possible power limitations• No indication of proximity

(acting alone)

Wire windings with ferrous cores

Microcontroller

Battery housing

Screw-in cap

Piston Navigation

Pros• Easier to feel direction• Better directional feedback• Can be used with gloves

Cons• Heavier• No indication of proximity

(acting alone)• May inhibit index finger

haptic ability

Standard servo

Push piston

Drive shaft

Battery Housing

Microcontroller

Screw-in cap

Track Ball Navigation

Pros• Easier to feel direction• Better directional feedback• Can be used with gloves

Cons• Heavier• Less compact• May inhibit index finger

haptic ability

Screw-in cap

Microcontroller

Battery Housing

Continuous servos & transmission shafts

Track ball

Torque Handle Navigation

Pros• Easier to feel direction• Better directional feedback• Can be used with gloves

Cons• Heavier• Moment of inertia/torque

concern

Screw-in cap

Standard servo

Transmission

Microcontroller

Battery housing

Roller Force/Stress Analysis

Force/Stress Cont’d