P14007: Wheelchair Assist Che-An Lee – Industrial and System Engineer Dan Schuster – Mechanical Engineer Phil Medalie – Mechanical Engineer Tom Elliot – Electrical Engineer

Agenda Functional Decomposition System Architecture Morphological Table Alternatives Considered Selected Concept Engineering Analysis Risk Assessment Test Plan Project Schedule

Functional Decomposition

System Architecture

Morphological Table Sense InclineAdjust Speed (Uphill)Apply Energy (uphill)Hold the wheelchair (uphill)Brake the Chair User InputGPSMotor (Electrical)Brakes Sensor (Electrical) Sensor on Wheels (Bike Computer) Any MotorRatchetMagnets MassUser Control (trottle)SpringElectrical Motor Sensor (Mechanical)Motor with clutchGear SystemsMagnetsSpring Measure Angle between frame and trailer Wheel MagnetsCable with counterweightAnchor Pneumatic/ hydraulics CameraGearsFlywheelSpringAnchor IR excess energy absorbed by springRocket EngineLocking Gearbox/Differ.Parachute LIDARBrakesCompress AirLocking Cable SystemAir Resistance Tank with water"Cruise Control"Pneumatic/ hydraulicsSpring/Rachet SystemCompressed Air/Water Handcranked Gear Wind up Windpower Infeasible Solution

Alternatives Considered ABCEFGHIJKLFunctions Selection Criteria Motor Gear System Spring Hand Crank Motor Gear System Motor Gear Systems Apply Energy (uphill) Locking Gearbo x Ratchet BrakesRatchetAnchor Cable System BrakesRatchet Hold the wheelchair (uphill) Gears BrakesGearsBrakesMagnetsGearsBrakesGearsBrakes Brake the Chair Elec. Sensor User Input Elec. Sensor User Input IR User Input Sense Incline Cruise Control User Control Motor with Clutch Cruise Control Gears Motor with Clutch User Control Adjust Speed (uphill) Material Cost Labor Cost Detachable Design Disengageable (time) Engageable (time) Turning Radius Overall Size Can be done in 2 Semesters Power Provided to chair by Device (movement assist) Complexity of Device Ease of Integration Reliability Safety Comfort Weight Sum + 's Sum 0's Sum -'s

Alternatives Considered Cont’d ABCEFGHIJKLFunctions Selection Criteria Motor Gear System Spring Hand Crank Motor Gear System Motor Gear Systems Apply Energy (uphill) Locking Gearbox Ratchet BrakesRatchetAnchor Cable System BrakesRatchet Hold the wheelchair (uphill) Gears BrakesGearsBrakesMagnetsGearsBrakesGearsBrakes Brake the Chair Elec. Sensor User Input Elec. Sensor User Input IR User Input Sense Incline Cruise Control User Control Motor with Clutch Cruise Control Gears Motor with Clutch User Control Adjust Speed (uphill) Material Cost Labor Cost Detachable Design Disengageable (time) Engageable (time) Turning Radius Overall Size Can be done in 2 Semesters Power Provided to chair by Device (movement assist) Complexity of Device Ease of Integration Reliability Safety Comfort Weight Sum + 's Sum 0's Sum -'s

Alternatives Considered Cont’d BCJKLMFunctions Selection Criteria Gear SystemSpringGear Systems MotorApply Energy (uphill) Ratchet Cable SystemBrakesRatchet Hold the wheelchair (uphill) GearsBrakesGearsBrakes Brake the Chair User Input Sense Incline User Control Adjust Speed (uphill) Material Cost Labor Cost Detachable Design Disengageable (time) Engageable (time) Turning Radius Overall Size Can be done in 2 Semesters Power Provided to chair by Device (movement assist) Complexity of Device Ease of Integration Reliability Safety Comfort Weight Sum + 's Sum 0's Sum -'s Continue? No Yes No

Selected Concept Sense Incline- User Input Adjust Speed (Uphill)- User Control Apply Energy (Uphill)- Gear System Hold the Wheelchair (Uphill)- Ratchet Brake the Chair- Brakes

System Integration Gear & lever and braking systems would be placed between wheel and chair frame Planetary gearbox would be placed on outside of wheel Secondary gear and levers would be placed either on side plate or where current wheel locks are

Engineering Analysis Torque Analysis Motor Analysis Spring Analysis Ratchet Benchmarking IR Benchmarking

Free Body Diagram and Coordinates

Equations of Motion and System Parameters

MATLAB Results T = 42 Nm, = 21Nm per wheel

Test Plan rqmt. #Engr. Requirement (metric)Test Procedure # of Tests Required Equipment Required Test Comments S1 Maximum weight at incline of 10 degrees where the wheel chair does not roll backwards Build structure that can increase in angle up to 15 degrees, place chair on structure with cables attached to frame to prevent tip over but not rollback. Incrementally place weights on chair until chair rolls/slides backwards. Refine weight increments as test continues for better fidelity. 10 Plywood base, car jack, cables Chair should not tip, coefficient of friction should be similar to asphalt S2User/Assistor disengageable Hill Holder Sit in chair, turn off devices, measure time to disengage 5None S3User/Assistor engageable Hill Holder Time study for how long the device takes to engage 10None S4 Maximum incline angle, before tipping over backwards with user weight of 300lbf Use structure from S1 test, place 300 lbs in chair, incrementally increase angle until chair tips over. 10S1 Fixture Test is for center of gravity check, should compare to baseline wheelchair S5 Maximum downhill speed at decline of 10 degrees at 300lbf user weight Pick slope on campus with similar slope to 1/12 grade, mark off distance, time user from start to finish with Gradual Grade activated 5None S6User/Assistor disengagable Gradual Grade Sit in chair, turn off devices, measure time to disengage 5None S7User/Assistor engagable Gradual Grade Time study for how long the device takes to engage 10None S8Desired Movement Assist Input Force Ratio Measure distance chair moves with a designated crank angle and compare it to original system S9 User/Assistor Disengagable movement assist Sit in chair, turn off devices, measure time to disengage 5None S10User/Assistor engagable movement assist Time study for how long the device takes to engage 10None

Test Plan Cont’d rqmt. #Engr. Requirement (metric)Test Procedure # of Tests Required Equipment Required Test Comments S11Total System Weight(Chair Plus Assist)Weigh chair with system attached3Scale S12Cost of Wheel Chair Assist System S13Wheel chair width when folded Measure chair's width when folded, compare to original 3 Tape Measure S14Wheel chair turning radiusSpin chair and measure turning radius3 Tape Measure S15Time to remove wheel chair assist system Measure the amount of time it takes for the user to completely detach the system None S16 Length of Wheel Chair + Movement System Measure the length of the chair Tape Measure S17Width of Wheel Chair + Movement SystemMeasure the width of the chair Tape Measure S18 Critical mechanical components have X number of use cycles Analytical and FEA package TBD

Risk Assessment IDRisk ItemEffectCause Likelihood Severity Importance Action to Minimize RiskOwner 1 Project Scope too large Team not able to deliver all deliverables Project Improperly scoped 236 Contact customer to prioritize the deliverables Team 2 Parts are ordered too late Prototype can’t be build and tested on schedule Uncertainty in lead time for parts 133 Order parts before winter break, Assign team member to order the parts during winter break Team 3 Parts needs to send out for machining Unexpected lead time and increased costs Part design is not producible by in house process 122 The design has the least specialized tooling and if required, incorporate into the project schedule, make sure the machine shop stay on the schedule with promised delivery time Team 4Expensive prototype Unsatisfied Customer, no funds for prototype Too many features, improper estimates 339 Include a range for all the parts estimates Team 5 Chair rolls backwards down slope Project failure, unsafe for use Unreliable stopping system 133Multiple failsafes for systemTeam 6System does not disengage Chair made unfit for normal use Improperly designed system 122Include multiple methods of disengaging Team

Risk Assessment Cont’d IDRisk ItemEffectCause Likelihood Severity Importance Action to Minimize RiskOwner 7 System does not engage Project failure, system does not provide assistance Improperly designed sensing system 122 Reliable device for activating system with failsafes (including manual activation) Team 8 System does not slow down chair on a decline Project failure, User moves faster than is safe Improperly designed system 133 Reliable device for activating system with failsafes (including manual activation) Team 9 System breaks/yields earlier than expected Chair is unusable improper analysis/ improper manufacturing techniques 224 Inspection of parts and installation, Perform durability tests to match with the desire durability, if system breaks it remains functional Team 10 Turning radius is too large System is not a good alternative to existing solutions Drive Wheels only turn one direction 111 Make sure the wheels can rotate independently. Team 11Expensive Manufacturing Cost Unsatisfied Customer, no funds for prototype Complicated Design, High Labor Cost 339Streamline Design, Design for ease of manufacturing, design of manufacturing analysis Team

Project Schedule

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