Smart Cane – P14043 Sub Systems Design Review Lauren Bell, Jessica Davila, Jake Luckman, William McIntyre, Aaron Vogel

Agenda Project Scope Concept Selection Engineering Requirements Component Breakdown Engineering Analysis Test Plan Risk Analysis Project Plan Audience Feedback Please

Project Scope Project Deliverables -Handle that provides directional signals to the user Objects to left or right of userBattery Life for 4-5 hours Comfortable HandleReasonable Cost - Simulation testing device

Concept Selection Final Concept Ideas Finger Scroll Palm Roller Palm Roller and Finger Scroll Final Concept Selection Palm Roller without Finger Scroll

Engineering Requirements

Estimated Power Consumption

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 Our measurements matched the study, therefore: Marginal Grip Pressure: 3 psi Maximum (Design) Pressure: 5 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, Aug. 201

Required Motor Torque Worst Case – Excessive grip stalls motor Maximum moment caused by design pressure 50.1 oz-in

Motor Type Selection Design Factors to meet Engineering Requirements Rotational speeds of 50 to 70 RPM Commonly available at 50 oz-in DC MotorStepper MotorServomotor Smooth rotationYesNoYes Won’t stall at slow shaft speed NoYes Generally maintains speed under varying grips NoYes Dimensions < 2”No (Gears needed)NoYes Cost < $30Yes Totals2 Yes3 Yes5 Yes

Engineering Analysis: Bump Rotation Characteristics Effective haptic zone – lower palm Effective Bump Height Bump Frequency

Component Breakdown

Bump Rotation/Roller Analysis Bumps per rotation Servo to Roller Spacing Effectiveness of our model – Audience?

Roller Force/Stress Analysis

Force/Stress Cont’d

Roller Assembly Support Elastic Materials Supports Support for Roller Assembly Audience Feedback please

Handle Material Selection Desirable Qualities Moisture wicking Higher Coefficient of Friction Possible Options Softex Neoprene Tennis Racquet Handle Cover Top Choice Synthetic Cloth - Nylon Tennis Racquet Handle Cover

Handle Weight Estimate ComponentQuantityWeight (grams)Weight (lbs) SpringRC SM-S4303R Servo Motor WhataGrip Handle Cover AA Batteries Cross-Bar/Plate for Servo /16" Ball Bearings MSP430 Microcontroller Total

Cost Estimate ComponentQuantityPrice per Item (US Dollars)Total Cost (US Dollars) SpringRC SM-S4303R Servo Motor Handle Cover Set of Batteries18.00 Cross-Bar/Plate for Servo (Cost of Aluminum) 2"x2"x1' Block /16" Ball Bearings MSP430 Microcontroller Rocker Switches Ultrasonic Sensors Handle Material* White Aluminum Cane Shipping Costs15.00 Total *Handle Material has not yet been decided

Test Plan

Simulation and Detection System

Micro Family Selection

Risk Assessment IDRisk ItemLikelihoodSeverityImportance 1Burning out micro controller326 2Software is ineffective236 3Haptic handle and testing systems integration issues236 4Not meeting customer expectations236 5Not obtaining parts on time224 6Battery malfunction224 7Over budget volunteers for user test are not established in time224 9Cane does not stay together, durability failure133 10Not completing software component133 11Haptic forces not being strong enough133 12Hardware and software integration133 13Detection is ineffective133 14Team Member leaves team133 15Cane gets dropped repeatedly on the ground133 16Excessive tapping133 17Handle material is not effective (Tears with consistent wear)133 18Uncoordinated team schedules122 19Selected power and components produce excessive heat122 20Necessary facilities and personnel are not available when needed122 21System is too heavy for desired cane weight111

Risk Growth Curve

Project Plan

Network Diagram

Immediate Next Steps Engineering Analysis [ 10/28] Power Requirement Electrical Subsystem [10/31 ] Design power supply Layout sensor, micro and power supply location Estimate weight distribution Pseudo code Mechanical Subsystem [ 10/31] CAD drawings Assembly drawings Select shelf parts Test Plan [ 10/28] Establish and draft test plans Risk Management [Weekly]