P14007: Wheelchair Assist

Final Presentation

Che-An Lee – Industrial and System Engineer

Dan Schuster – Mechanical Engineer

Phil Medalie – Mechanical Engineer

Tom Elliot – Electrical Engineer

Sponsor: Multidisciplinary Senior Design Program

Agenda

Project Description

Design Concept

System Architecture

Project Status

Test Results

Conclusion

Project Description

Design a low cost device that maintain the characteristic of a

manual wheelchair and prevent the wheelchair to roll back

Key Customer Needs and Engineering Metrics:

Design Concept

Pawl

Brake Disk

Bearing Block

Ratchet

Caliper

Design Concept Cont.

Pawl

Brake Disk

Bearing Block

Ratchet

Caliper

Design Concept Cont.

Left Wheel Generator

Right WheelGenerator

Bridge Rectifier

BridgeRectifier

Buck-Boost Regulator

Circuit Breaker

USB FemalePlug

ZenerDiode

Design Concept Cont.

1. Left Generator Input Banana Clips

2. Right Generator Input Banana Clips

3. Both Bridge Rectifiers

4. Circuit Breaker Switch

5. Zener Diode

6. Buck-Boost Regulator 5 Volts

7. USB out with USB Circuitry.

System Architecture

Project Status

Design meets all customer needs except:

Weight (0.5 lbs over)

Charging system is not on the chair

Unable to test:

Maximum weight at 10 degree incline

Completed BOM for working prototype

Completed all mechanical systems under budget

Test Results

Specification Tested Target Value Result

Max weight at 10 degree incline 400 lbf 260 lbf

Time to disengage 2 sec 3.56 sec

Time to engage 0.5 sec 0 sec

Max. incline angle 6 ° 13 °

Max. downhill speed 3 mph User Varied

Time to disengage 2 sec 0 sec

Time to engage 0.5 sec 0 sec

Turning radius 1 ft. 0 ft

Time to remove system 10 min 6 min

Current output at 1mph 0.25 amps 0 amps

Current output at 4mph 1 amps 1.04 amps

Rollback distance 1 inch 0.25 inches

Time (replacement) 15 min 9 min

Input force 10 lbf 1.32 lbf

System Weight 20 lb 20.5 lb

Torque with 5 ohms resistive load 1 lbf 2.72 lbf

Total System Cost (Purchased Parts) $500 $438

Wheelchair Width when folded 18 inches 17 inches

Wheelchair Width 29 inches 25.5 inches

Wheelchair Length 40 inches 38.5 inches

Conclusion

Current Results:

Demonstrated a cost

effective solution for

rolling backwards

Design maintains

important characteristics of

a manual wheelchair

Generator system

succeeded in charging a

battery

Future Work:

Weight reduction

Universally adaptable to

most manual wheelchairs

Incorporate movement

assist into design

More efficient generator

system to charge batteries

at lower speeds

Comments/Questions?