Wheelchair for Basketball

List of group members

Albert Painter
Amber Butcher
Daniel Hardin
Kevin Cady
Laishka Bruno

Abstract

This project consists of designing a machine to shoot a basketball for a girl with limited mobility. Through this machine the girl will be able to shoot a basketball into a ten-foot-high basketball hoop.

Introduction

The girl has limited mobility, strength, and is in a powered wheelchair. She would like to be able to play basketball with her family.

Design Specifications

We met with the client who is interested in being able to shoot basketball with her little brother. She is confined to a wheelchair and has little mobility in her arms, She is left handed and is able to hold a game controller. She is only able to press buttons and move her wrists enough to play games such as Wii sport. This limitation led us to understand the constraints concerned with using a remote in our design. Her wheelchair is motorized and can lower completely to the ground if need be. I believe the meeting went very well she is very excited about what we are doing. The family had some great ideas and is willing to help make the wheelchair accessible to us.

1. Cannot require physical input beyond client’s capabilities
2. Cannot impact functionality of client’s wheelchair
3. Must be able to move around gravel basketball court at client’s home
4. Must be able to meet basketball goal height of 8-10 feet
5. Must shoot standard size 6 basketball (weight ~8lb)
6. Must be able to shoot from a distance of 3-15 feet

Design Concepts

flickr:6849825001

This shooting machine uses compressed air generated by a small compressor to produce the energy needed
to shoot the ball. Compressed air could also be used to control the aiming of the device. To shoot the basketball,
the piston assembly would be locked into firing position and pressurized to a desired pressure (depends on distance and height to the goal).
When the user is ready to shoot, the lock is released allowing the piston to push the ball down the tube. Pressure will then be released from the piston
allowing it to return to the firing position.

Concept Evaluation

% Spring Spring Adjusted Air Air Adjusted Wheel Wheel Adjusted
Safety 30 1 .3 4 1.2 3 .9
Durability 20 2 .4 2 .4 4 .8
Ease of Fabrication 15 3 .45 1 .15 3 .45
Ease of Use 15 2 .3 3 .45 4 .6
Cost 10 4 .4 2 .2 2 .2
Weight 10 4 .4 2 .2 2 .2
Total 2.25 2.6 3.15

Design Overview

Analysis

The aspects of the machine we are interested in analyzing are:
-the necessary exit angle of the ball given the maximum height and minimum distance from the goal;
-holding the previous angle, the required exit velocity of the ball from the maximum distance;
-from the previous velocity the exit angular velocity of the spinning wheels;
-from the exit angular velocity and a desired coefficient of fluctuation, the initial angular velocity of the wheels and the energy input of the engine over the duration of the launch.

MATLAB will be used for most of the computing.

Exit Angle

Using the kinematic equations:

xf = x0 + v0*t - 1/2*g*t2

and

vf2 = v02 - 2*g*(xf - x 0),

a ball shot 8 ft away from a 10 ft hoop with a max height of 14 ft will require a launch angle of 79.5o

Vmax

Using conservation of energy:

1/2*m*Vi2 + m*g*hi = 1/2*m*Vf2 + m*g*hf,

a ball shot from 20 ft away from the same hoop will require a velocity of 42.2 ft/s

wexit

Using the velocity to angular velocity equation:

v = D*pi*w,

the final angular velocity of the wheels will need to be wf = 1210 RPM

wi and E

Using the equation coefficient of fluctuation and an adjusted energy balance:

k = (wmax-wmin)/wavg

and

Emotor + 2*1/2*I*wi2 = 2*1/2*I*wf2 + 1/2*m*v2

From Autodesk drawings of the wheel we find the moment of inertia to be .005304 slug*ft2, the mass of a basketball is .02851 slugs and our desired coefficient of fluctuation as .05, we find wi = 1270 RPM and the energy required of both motors during the launch .0963 Btu.

Results from other initial distances

flickr:6986082263

Bill of Materials

Name Part Number Quantity Price/Unit Total
Op Amps Quad 595-LM2900NE4 50 $0.15 $7.50
MOSFET NMOS SINGLE N-CHANNL 30V 9A 621-DMN3030LSS-13 20 $0.42 $8.40
Carbon Film Resistors - Through Hole 1MOhm 1/3W 1200PPM 279-CFR25J1M0 20 $0.01 $0.20
Carbon Film Resistors - Through Hole 1KOhm 1/3W 1200PPM 279-CFR25J1K0 100 $0.01 $1.00
Encoders, Decoders, Multiplexers & Demultiplexers IC MULTIPLEXER 863-MC74HC259ADR2G 5 $0.16 $0.80
MOSFET SIPMOS PWR-TRANS 100V 47A 726-IPP47N10SL-26 10 $1.48 $14.80
High Power LEDs - Single Color Blue 0.5 Watt 828-OVS5MBBCR4 10 $0.58 $5.80
High Power LEDs - White White 18.1lm XLamp MLB LED 941-MLBAWTA1000VE8 20 $0.53 $10.60
High Power LEDs - Single Color Red 0.5 Watt 828-OVS5MRBCR4 10 $0.33 $3.30
High Power LEDs - Single Color Yellow 0.5 Watt 828-OVS5MYBCR4 10 $0.33 $3.30
High Power LEDs - Single Color Amber 0.5 Watt 828-OVS5MABCR4 15 $0.33 $4.95
PCBs / Circuit Boards DOUBLE SIDED 6X9 LEAD FREE 1/16 COP 590-533 2 $8.46 $16.92
Aluminum plate 12" x 6' x .25" 9246K45 2 $77.21 $154.42
Aluminum rod D1 3/4" x 1' 8974K681 1 $16.71 $16.71
Aluminum tube 2" x 2" x 1' 88875K751 2 $17.82 $35.64
Aluminum tube 2" x 3" x 1' 88935K121 2 $14.77 $29.54
Aluminum tube 1" x 1" x 1' 88875K541 1 $6.89 $6.89
Sports Tutor Wheel Pair N/A 1 $90.00 $90.00
Sports Tutor Motor N/A 2 $100.00 $200.00
Sports Tutor Battery Pair N/A 1 $75.00 $75.00
Caster 2877T31 4 $18.10 $72.40
Nuts and Bolts N/A 42 $1.20 $50.40
Total $808.57

Part Drawings

flickr:6986468279

Implemented Design

Include pictures of the final product.

Summary and Conclusions