12/7/2004 AME470 Ltd. - Team Pratham 1Open-Aid TEAM PRATHAM Team Leader: Matt Ryan Chief Engineer: Nick Martin Fabrication: Reed Langton CADCAM: Fraterno

12/7/2004 AME470 Ltd. - Team Pratham 1

Open-AidOpen-Aid

TEAM PRATHAMTEAM PRATHAMTeam Leader: Matt RyanTeam Leader: Matt Ryan

Chief Engineer: Nick MartinChief Engineer: Nick MartinFabrication: Reed LangtonFabrication: Reed Langton

CADCAM: Fraterno VilaCADCAM: Fraterno VilaElectronics/Control Engineer: Electronics/Control Engineer:

Gabriel LetonaGabriel Letona

12/7/2004 2AME470 Ltd. - Team Pratham

OutlineOutline Problem DefinitionProblem Definition Product RequirementsProduct Requirements OperationOperation Prototype Prototype Design IssuesDesign Issues Strengths and WeaknessesStrengths and Weaknesses Budget SummaryBudget Summary


Problem DefinitionProblem Definition

Break the seal on jars and bottles Break the seal on jars and bottles without requiring the user to apply the without requiring the user to apply the torque necessary to open themtorque necessary to open them


Product RequirementsProduct Requirements

Container Specifications

Twist off cap/lid

Total Height 2 - 10 in.

Body Diameter 1.5 - 5 in.

Lid Height 0.3 - 1.0 in.

Lid Diameter 1 - 5 in.


Open-AidOpen-Aid

Ability to open a glass or plastic Ability to open a glass or plastic containercontainer

Uses a microprocessor with Uses a microprocessor with feedback from sensors to control the feedback from sensors to control the driving motorsdriving motors


Prototype vs. ConceptPrototype vs. Concept• Housing - Box vs. Cylinder

• Height Adjustment

• Fabricated bottom half


OperationOperation


Programming (Opening Programming (Opening Container)Container)

Yes

No

Stop bottom assembly motor

Does Hall effect sensor 1 still sense

magnet?

Hall effect sensor 2 senses magnet

Count to 1

second

Stop turning top assembly motor

Start turning bottom assembly motor

Sense top assembly

contact switch

Has bottom assembly contact

switch been pressed?

No

Turn top assembly motor

on

Plug in

appliance

Press ‘start’ button

Yes

Stop bottom assembly motor and

go to release operation


Programming (Releasing Programming (Releasing Container)Container)Reverse top assembly motor

Sense top assembly hall effect sensor

Stop top assembly motor

Reverse bottom assembly motor

Hall effect sensor 1 senses magnet

Stop bottom assembly motor


The PrototypeThe Prototype


The PrototypeThe Prototype• Sensors - Contact switches moved to breadboard

Prototype

Concept


Design IssuesDesign Issues

Torque Requirements Torque Requirements Motor SelectionMotor Selection Plate DesignPlate Design Gripping ComponentsGripping Components ElectronicsElectronics


Torque RequirementsTorque RequirementsREQUIRED TORQUE EXPERIMENTAL DATA

Container Weight Force Lever Arm Torque Torque

(kg) (N) (m) (N-m) (oz-in)

Glass Applesauce Jar** 1.275 12.51 0.26 3.25 460.52

Glass Salsa Jar 3 29.43 0.243 7.15 1012.72

Plastic Powerade Bottle 0.75 7.36 0.262 1.93 272.98

Glass Snapple Bottle 1.2 11.77 0.253 2.98 421.76

**For this first experiment, the jar was laid horizontal. The equivalent mass of the lever arm is factored into the weight shown here


Motor SelectionMotor Selection

Buehler 12V DC Gearmotor w/ 6:1 Gear Train

Output Power 0.015 hp

Torque 1944 oz-in

Angular Velocity 6.25 rpm

Weight 1.5 lbs

Diameter 1.2 inches

Length 3.3 inches

Shaft Length 0.4 inches

Motor Selection:


Gear TrainGear Train

6:1 gear ratio 6:1 gear ratio required to transmit required to transmit operating torque with operating torque with the Buehler DC motorthe Buehler DC motor

Stainless steel clamp Stainless steel clamp hub gears from Berghub gears from Berg

Clamps secure gear Clamps secure gear and pinionand pinion


Plate DesignPlate Design

Resulting Force on Grips from Spiral Groove

Grip rests at intersection of linear and spiral grooves

Motor output results in the spinning of the Plate w/ Spiral Grooves, causing the Grip to move towards the center of the plates along the linear groove

Grip

Plate w/ Linear Grooves

Plate w/ Spiral Grooves

Linear Groove

Spiral Groove

Convergence Angle


Plate DesignPlate Design

Torque Key

Torque Key

Motor

Gears

• Torque Key is fastened to the central shaft with a spring pin

• Torque Key interlocks with Plate w/ Spiral Grooves


Gripping ComponentsGripping Components

Concept – three Concept – three gripping gripping components components consisting of a consisting of a gripping arm riding gripping arm riding in a slotted bracket, in a slotted bracket, with a spring and with a spring and contact switchcontact switch

Inserts into spiral Inserts into spiral and radial platesand radial plates

Spiral

Radial


Gripping ComponentsGripping Components Prototype – single unit with high-friction Prototype – single unit with high-friction

synthetic polymer padssynthetic polymer pads Problem – prototype slips on glass containersProblem – prototype slips on glass containers

Radial Plate

Spiral Plate


Electronic SchematicElectronic Schematic


Microcontroller System Microcontroller System and and

Power SourcePower Source Minimax Minimax MicrocontrollerMicrocontroller Microprocessor Microprocessor

PIC16F877APIC16F877A Demands 6 to 12V DCDemands 6 to 12V DC 100mA minimum 100mA minimum

currentcurrent Provides 5VProvides 5V

External Power External Power SourceSource 120V AC from outlet120V AC from outlet Use of an AC-DC Use of an AC-DC

adapter power source adapter power source converterconverter


SensorsSensors Magnetic Hall Effect sensors are used to control Magnetic Hall Effect sensors are used to control

the rotation of the plates during the opening of the rotation of the plates during the opening of the containerthe container

Magnet 1

Housing

Hall Effect Sensor

Container to Open

Lower Plate Assembly


SensorsSensors

Contact Switches

Hall Effect Sensor & Magnet


H-BridgeH-Bridge 2 NMIH-0030 H-bridges DC motor applications from 6 to 18 V up DC motor applications from 6 to 18 V up

to 5 A currentto 5 A current Provides forward, reverse, and brake

modes of operation.


Strengths and Strengths and WeaknessesWeaknesses

Component Strength Weakness Importance

Spiral Plateunlimited number of

potential grippers; one motor per plate assembly

Carefully selected geometry

high - the basis of design for the entire product

Magnet Sensorsonly sensors require

power, magnet does not

Requires close proximity to moving

plates

medium - sense position of container; there are no wires

to tangle

Grippersspring loaded for more

uniform grasping

increases part count, only a fixed force reaches contact

switch

medium - ensures that all grippers grip with even force

Contact Switches Small wires can get twisted

if not controlled

medium - wires twist, which must be accounted for in the

design

Gearspositive contact/force

transmission

may be loud, small pitch requires

precision

high - gears transmit the torque to the container applied by the motors

Height adjustment

automatically moves up with lid displacement

requires user to initially adjust it

manually

low – automated system not necessary; user able to lift

top assembly manually


Budget SummaryBudget Summary

Most expensive components:Most expensive components:

- Large Gear - Large Gear $43.00$43.00

- H-Bridge - H-Bridge $30.00 $30.00

Budget Available:Budget Available: $400.00$400.00 Total Budget used: Total Budget used: $338.00$338.00 Budget Left: $62.00Budget Left: $62.00

Documents

12/7/2004 AME470 Ltd. - Team Pratham 1Open-Aid TEAM PRATHAM Team Leader: Matt Ryan Chief Engineer: Nick Martin Fabrication: Reed Langton CADCAM: Fraterno