Final Presentation

ME 4182Team 5 Guys Engineering + 1

Nathan Bessette Rahul BhatiaAndrew Cass

Zeeshan SaiyedGlen Stewart

YJ Chok

Agenda

• Midterm Recap

• Engineering Analysis

• Final Design

• Prototype• Prototype

• Prototype Subsystem Overview

• Video Demonstration

• Suggestions for Improvement

• Questions

Automated Whiteboard Wiper

• Recall: Problem Statement – Regular

whiteboards take a relatively long time to

erase, a task that may be difficult for older or

disabled users.

• Recall: Objective – To create an electro-• Recall: Objective – To create an electro-

mechanical system that automates the eraser

function for the whiteboard, saving time and

effort in class

– Especially useful to older or disabled users

– Useful in education and corporate environments

Recall: Midterm Presentation

Selected Design: Dual Swipe Cleaning System

Engineering Analysis

• Important Considerations:

– Overcome friction forces between eraser and dry

erase board

– Select motors to provide sufficient power for – Select motors to provide sufficient power for

horizontal and vertical motion

Supplier

Motor

Number Motor Name Description

Ref.

Voltage

Gear

Ratio

Stall

Torque

(lb-ft)

Free

Speed

(rpm)

Free

Speed

(rad/s)

Fisher-

Price

74550-0642 Power Wheels Motor and

gearbox 12 181 56.8 133 13.9

Globe 409A587 2WD/4WD

transfer mtr.

Planetary

Gearmotor 12 117 9.59 80 8.4

• Horizontal Torque Required: • Vertical Torque Required:

Torque Requirements and Motors

• Horizontal Torque Required:

T = Fmax tension due to friction·rpulley

= (7 lbs.)(2.25 in.)

= 15.75 lb-in

= 1.3 lb-ft

Treq = 1.3 lb-ft minimum

• Vertical Torque Required:

T = Fmax(friction+weight)·rgear

= (12 lbs.)(1.875 in.)

= 22.5 lb-in

= 1.875 lb-ft

Treq = 1.875 lb-ft minimum

Fweight = Weight of Motor Assembly (3 lb est.) plus Eraser Backing (2 lb est.)

Final Design

Prototype

Subsystem: Vertical Motion

• Vertical motion comes from 12V Globe motor

attached to a rack and pinion and guided by

controller input

• Rack and pinion allows for full 48’’ vertical range

from 24” eraser (pinion attached to motor with set

screws & rack fastened to industrial drawer slider)

Subsystem: Horizontal Motion

• Horizontal motion comes

from 12V Fisher Price motor

attached to a double pulley.

• Ropes connect to top and

bottom set of double pulleys to

transfer motion.

•Rubber bands inside pulleys

allow for sufficient friction for

rope to move eraser arm

against friction from

board/eraser contact

• Wheels designed for exact fit

into aluminum rail tracks allow

for smooth movement

Subsystem: Eraser

• Normal force to board provided by

felt and sponge eraser.

• Compressed sponge used to provide

equal distribution of force across eraser.

• Phidgets control board with 2 motor

control outputs provides horizontal

and vertical movement.

Subsystem: Controller Board

• Programming completed in MATLAB.

• Mounting of controller and wire

hidden behind the board for safety.

Automatic Whiteboard Wiper

• Prototype Demonstration Video!

Difficulties Encountered

• Horizontal motion with ropes

• Eraser backing material

• Motor and pulley physical meshing

implementationimplementation

• Mounting of vertical motor and rack

• Harsh dry erase board surface

Future Improvements• Implementation of safety covers over mechanical

parts

• Sourcing of AC power integration for motors

• More easily accessible eraser replacement/rail

maintenance

• Sourcing/design of cheaper rail-running wheels• Sourcing/design of cheaper rail-running wheels

• More precise control of motor path (grid/indexed

system with physical or electrical stop sensors

• For extra harsh board surfaces, implementation of

cleaning solution spray nozzle or vibrating eraser

through controller implementation of harmonic

excitation.

Questions?