Watermelon Ripeness Sensor

Melon Inc.In Search of Perfect Melons.

Jason L. Firko

Allan Cohen

Matt Behr

Dave Bartoski

Watermelon Ripeness SensorMelon Inc. “In search of perfect melons”

Jason L. Firko

Allan Cohen

Matt Behr

Dave Bartoski

Customer: Ed Kee Advisor: Dr.James GlanceyMission: Develop a non-destructive method and apparatus for accurately measuring the

properties of watermelons which could correlate to ripeness.

Approach: Use customer wants to research and develop the most useful solution to the problem of determining the properties of watermelons which could be used in the development of non-destructive watermelon ripeness testing. Design a prototype and test it in an actual working environment.

Presentation Overview

• Introduction– Mission, background, wants, constraints

• Benchmarking

• Metrics

• Concept generation & selection

• Concept development

• Prototype – testing, budget, hours

• Conclusion

Background Watermelon market is a large

Grown on 5 Continents Grown in 90 countries Annual production 50 billion lbs./year 75% of the melons bought whole Large domestic and international market

Problem with a long history - 1905 University of Georgia Study

There are currently no accurate non-destructive testing methods commercially available

Initial Systems Benchmarking

Current Methods Of Watermelon Testing Traditional - Thumping, stem color, skin color,

other traditional methods Destructive Testing - Sucrometer readings Near Infrared Testing - Experimental technique of

sensing sugar content• Acoustic Testing - University of Oklahoma

Systems Benchmarking Cont.

Related Procedures (Fruits and others)Thumping/Resonance Tires, FruitsAcoustic testing Acoustic emission

testingUltrasonic testing Materials, MedicalOptoelectrics ApplesIntrusive testing Medical(syringes)Nuclear magnetic resonance Fruits, MedicalElectronic sniffing Strawberries

Customers & Wants

10 0.45 0.25 0.15 0.1 0.05Name Organization Rank 1st Want 2nd Want 3rd Want 4th Want 5th Want

Mr. Ed Kee Sponsor 10 Accurate Portable Durable Cheap FastJ ohn Hastings Farmer 8 Portable Accurate Durable Easy to Use Food QualityJ eff Wooden Farmer 8 Portable Accurate Durable Easy to Use FastMark Collins Farmer 8 Accurate Durable Portable Fast Food QualityMack Farms Broker 7 Accurate Fast Easy to Use Durable Food QualityOdanna Mathews Giant Foods 6 Accurate Cheap Easy to Use Food Quality DurableBill Roberts Acme 6 Accurate Cheap Food Quality Durable Easy to UseDavid Thorp FDA 6 Food Quality

USDA 6 Food QualityKaren Clark Produce Stand 6 Cheap Accurate Easy to Use Portable Food QualityJ oe Meloneater Consumer 3 Cheap Accurate Food Quality

Top Wants and Constraints

1. Accuracy 2. Portability 3. Food Quality 4. Cost 5. Durable 6. Easy to Use 7. Fast 8. Versatility 9. Maintenance 10. Service Life

1. Maximum - $3000 budget

2. Abide by all FDA regulations Food quality

3. Abide by all OSHA regulations Safety standards

Metrics/Target Values Metrics

Provide a means of objective measurement Eliminate ambiguity

Target Values Derived from customer wants, functional benchmarking,

continued customer dialogue Contact regulatory agencies Listed with related wants (ranked)

Metrics and target values have been evolving with the project throughout the year

Metrics & Target Values Accuracy Target Value

Correlation coefficient 0.5 Dimensional measurement < 0.5in Sound wave deviation /max signal <.05

Portability Weight 51 lbs. Size (dimensions) 3’ Sides # People - transport/operation 1

Durability

Hours of continuous operation 12 hrs. Impact resistance 30 lb static load

Ease of Use / Speed Level of education required Some college

Time to train 4 hr. Number of steps 5 Time/cycle 10 sec. Time per shipment 2 hrs.

Food quality Size of intrusion 1 mm. Bacteria introduced 0 Visual quality inspection rating 9 (out of 10) Service life/Maintenance Estimated years of service 5 yrs Cost/cycle (parts, upkeep, etc) $.01/cycle

Versatility Additional sensor adaptable Yes # of uses (melon types, sizes, etc.) 4

Cost Production cost (materials) $1500

Concept Generation

ACOUSTIC RESONANCE

ELECTRICAL PROPERTIES

ULTRASOUND NUCLEAR MAGNETIC

RESONANCE (NMR)

SONIC TESTING - SINGLE FREQUENCY

SONIC TESTING - WHITE NOISE

INFARED ENERGY IMPACT STRAIN GAUGE FLUID EXTRACTION

Concept Evaluation/ Selection Process

Is this a viable solution?Evaluate in terms of ranked metricsPresentation - Time Constraints

Method - Comparison with metrics(related wants) Strong in metricsWeak in metrics Notes on concept

SSD and Testing results lead to selection

Concept Evaluation

Nuclear Magnetic Resonance *Out of Budget - $60,000 - $1,000,000

Sonic Testing- Single Frequency Food quality, Speed *Need Proper Environment Easy to use, Accuracy, Maintenance, Cost, Environment

Sonic Testing- White Noise Food quality *Need Controlled Conditions Speed, Cost, Accuracy, Portability, Easy to use

Infrared Accuracy, Speed, Food quality *Auxiliary Power Expensive, Easy to use, Portability Equiptment Needed

Concept Evaluation (Cont’d)

Energy Impact Quick, Easy, Food quality, Portability, Durability Accuracy *Not Internal

Strain Gauge Portable, Food quality *Rind Properties Easy to use, Speed, Accuracy

Fluid Extraction With Syringe Accuracy, Portability, Easy to use *Intrusive Food quality, Maintenance

Ultrasound

Testing - CCMCatch 22

High frequency - Cannot penetrate rind Low frequency - Cannot sense density changes

Other problems - Air pockets, Seeds Food quality, Service life, Versatility Accuracy, Portability, Cost, Speed

Not a viable sensing mechanism

Electrical Properties

Resistance testingRC modeling Data normalized for physical parameters &

sugar content Portability, Cost, Maintenance, Service life Accuracy, Food quality, Speed

No correlation found - not a viable sensing mechanism

Acoustic Resonance Testing Based on traditional method -

acoustic properties have been used to determine ripeness

Resonance traditionally indicates ripeness

Ripening of melons changes physical structure which should alter acoustic response

Accuracy, Portability, Food quality, Cost, Easy to use, Fast

Maintenance, speed

General Setup

Main parts Sensory Signal conversion Peripheral equipment Measurement equipment Data Analysis/Interface Thumper

Feasibility of concept

• Must determine:– Repeatability and reliability– Determination of relevant variables– Required prototype components– Possible signal characteristics which may relate

to ripeness

• Testing of concept aids in design evolution

• Performed testing - 18 melons -All melons were in ripe range (8 - 12% sugar)

• Determined repeatability and reliability-Stationary repeated testing -Impact height

-Background noise -Turning

• Background noise - crucial for feasibility -Tested with working environment noise

-voices, background equipment, etc. (65db)

Concept Feasibility - Testing

• Varying Height of Thumper– Repeatable at each height– See clear shift in signal amplitude– Amplitude could indicate physical properties

if impact is kept constant

0 50 100 150 200 250 300 350 400 450 50010-15

10-10

10-5Varying height

Melon 1

abc

0 50 100 150 200 250 300 350 400 450 50010-15

10-10

10-5

Melon 2

0 50 100 150 200 250 300 350 400 450 50010-15

10-10

10-5

Melon 3

Frequency (Hz)

• Rotation of watermelon– Indicates uniform internal structure– One possible source of error during

operation is eliminated

0 50 100 150 200 250 300 350 400 450 50010-14

10-12

10-10

10-8

10-6

10-4Turning Melon

Melon 2

Frequency (Hz)

abc

Prototype Components

• Developed through wants and concept testing– System Elements

• Sensory: Standard microphone elements

• Signal conversion: PCMCIA Card

• Peripheral equipment: power source, connecting board/cable

• Measurement equipment: potentiometers

– Data Analysis/Interface

• Laptop with Labview interface

• Program components: continuous scanning, system voltage monitoring/warning, required displays/analysis

Prototype Evolution

[i] - Experimental set up - Dr. Sun’s Lab

[ii] - Initial prototype

[iii] - Final testing apparatus

Prototype Evolution

Lab Setup:- Had the basic elements- Large separate units- AC powered

Initial Prototype:- Basic layout determined- Portable- DC Powered

Final Prototype:- Easier to use- More durable- Even more portable- Faster- Lower maintenance

Final Prototype

Prototype: Physical Features• Easy adjustments

• Sealed electronics

• Portable

• Easy to inspect

• Low maintenance

• Durable construction

Final Prototype General Electrical LayoutLaptop Computer Microphone

Connector

Microphone

Potentiometer

Potentiometer

Battery3.0 V

Battery 1.5V

Battery 1.5V

Prototype Display/Interface

Repeatability of Signal Acquisition

Seven repeated signals

Average standard deviation:

= 6.70 binary data points max signal = 150 binary data

points / max signal = 0.0447

Steady State Frequency Calculation

6 cycles616 840

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6cycles#

840x

616x

cycles)(5000)(#

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ëfrequency

2

1

1

12

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√√↵

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* Ten waveforms analyzed for characteristic frequency

Results/CorrelationRaw Data

Correlation found between dominant frequency and sugar content

Promising correlation coefficient found (R^2=.4436)

Normalization

Normalized using volume approximation as multiplier.

Significantly improves correlation coefficient (R^2=.8086)

lengthwidthnorm ??= 2λλ

Metrics with Target Values and Test Results

Accuracy Target Value Test Result Correlation coefficient 0.5 0.81 Dimensional measurement < 0.5in 0.25in Sound wave deviation /max signal <.05 0.045

Portability Weight 51 lbs. 18.2 lbs Size (dimensions) 36 in Sides 17 x 17.5 x 11 in # People - transport/operation 1 1

Durability Hours of continuous operation 12 hrs. 4 hrs./336 hrs. Impact resistance 30 lb static load 30 lb static load

Ease of Use / Speed Level of education required Some college Some college

Time to train 4 hr. 3 hr. Number of steps 5 6 Time/cycle 10 sec. 12 sec. Time per shipment 2 hrs. 2.1 hrs.

Food Quality Size of intrusion 1 mm. 0 mm. Bacteria introduced 0 0 Visual quality inspection rating 9 (out of 10) 10

Service Life/Maintenance Estimated years of service 5 yrs 10 yrs Cost/cycle (parts, upkeep, etc) $.01/cycle $.003/cycle

Versatility Additional sensor adaptable Yes Yes # of uses (melon types, sizes, etc.) 4 4

Cost Production cost (materials) $1500 $1080.81

Budget Item $Cost$$ Computer & accessories 975.70$ Base & accessories 25.85$ Microphone assembly 7.54$ Thumper assembly 11.89$ Caliper assembly 41.40$ Miscellaneous 18.43$ Total 1080.81

Event Hours• Engineering development time 1135.9 • Machine time 50.03

Future Improvements

Addition of filters to improve FFT analysis Adapters for length caliper Purchase a spare battery & power inverter Motorized thumper Further refine data correlation Incorporation of ripeness correlation into program Replace laptop with microprocessor

Conclusions• Our customer is satisfied with the result of the project.

• The customer is encouraged by the determination of an initial correlation.

• The speed of the apparatus is 20% slower then we had hoped.

• The hours of continuous use for the laptop is currently lower then initially desired.

• Our customer is very pleased with the portable design of the device.

• We have reached the majority of our target values and are pleased with the final prototype.

Project GoalSatisfied Customers!