P11562 MIS Frame and Stabilization Module

P11562 MIS Frame and Stabilization Module

Detailed Design Review

Rob Bingham

Matt Moore

Karen Smith

KGCOE MSD of 38 Technical Review

KGCOE MSD Technical Review Agenda

Meeting Purpose: Review and receive feedback for the design of P11562 Frame and

Stabilization Module subsystems and overall design.

Materials to be Reviewed:

Needs/Specs

Subsystem Design

Risk Assessment

Bill of Materials

Preliminary Test Plan

Meeting Date: Feb 11th 2011

Meeting Location: 09-2255

Meeting time: 8:00 am to 10:00 am

Timeline:

Meeting Timeline

Start time

Topic of Review

8:00 Project Background 8:05 Needs and Specs 8:15 Stabilization System 8:35 Impact Foam System 8:50 Frame System 9:05 Risk Assessment 9:15 Areas of Concern 9:25 Bill of Materials 9:30 Test Plan 9:50 MSD II Action Items 9:55 Conclusion


Table of Contents:

Project Background………………………………………………………………………………………………………...4

Mission Statement…………………………………………………………………………………………………………..5

Subsystems…………………………………………………………………………………………………………………….5

Customer Needs……………………………………………………………………………………………………………..6

Specifications…………………………………………………………………………………………………………………6

Stabilization System………………………………………………………………………………………………………..7

Impact Foam System……………………………………………………………………………………………………..12

Frame System……………………………………………………………………………………………………………….15

Risk Assessment…………………………………………………………………………………………………………...19

Areas of Concern…………………………………………………………………………………………………………..20

Bill of Materials…………………………………………………………………………………………………………….20

MSD II Action Items………………………………………………………………………………………………………21

Appendix A: Test Plan…………………………………………………………………………………………………...22

Appendix B: Works Cited………………………………………………………………………………………………38


Project Background

Project Name: MIS Frame and Stabilization Module Project Number: P11562 Project Family: Open Source / Open Architecture Modular Imaging System Track: Printing & Imaging Systems Start Term: 2010-2 End Term: 2010-3 Faculty Guide: Dr. Alan Raisanen Primary Customer: CIS, Carl Salvaggio

Mission Statement


The Frame and Stabilization project's mission is to create a module interface for the UAV

platform, standardize the camera mounting interface, design and implement the camera

shock and vibration systems, minimize the module weight, and maximize the impact

survivability.

Subsystems

Stabilization System – Reduces vibration of camera using a 3 axis shock mount system

allowing camera to take clear images from the air.

Impact Foam System – Reduces G force felt by camera and components during impact

allowing maximum survivability in case of an incident.

Frame System – Contains camera and components in a durable lightweight frame that fits

in the cargo holding area of UAV C.


Customer Needs

Specifications


Stabilization System

Customer Need:

Isolate camera lens from engine propeller vibrations.

Specification Theory:

The specification for the damping material will be determined by the natural frequencies of the

material, the camera lens, and the engine/propeller system. Therefore the ideal material can be

determined through analysis of the natural frequencies of the camera lens and the engine/propeller

system.

Specification Calculations:

Cruise speed of aircraft is typically 75% of the maximum speed of the aircraft.


The ideal natural frequency of the material would be an order of magnitude(1/10) less than the

natural frequency of the engine at cruise speed. A marginal value for the natural frequency of the

material would be half an order of magnitude (1/5) less the natural frequency of the engine at

cruise speed.

Current Vibration Isolation System:

The material that is currently being used for the vibration isolation system is Sorbothane Shore 30

oo. The customer has stated that the current damping material is unacceptable because it allows

for too much displacement of the camera lens during operation.

Calculations of Current System:

The mass of the camera lens, cross-sectional area of the shock mounts, and the thickness of the

shock mounts are from the documentation of MSD P09561.

The Young’s Modulus of the damping material can be found at

http://www.sorbothane.com/material-properties.php

Poisson’s Ratio of Sorbothane is assumed to be the same as similar materials (ie Polyurethane and

Rubber)



Proposed Alterations:

In order to decrease the displacement of the camera lens during operation of the vibration isolation

system, the stiffness of the damping material must be increased without increasing the natural

frequency to a range that won’t allow proper vibration isolation. The natural frequencies of

materials tend to increase as stiffness and shear modulus of the material increase (if the area, mass

and thickness values are kept constant). In order to find the ideal material for the system, the

previous equations will be used in reverse order to take the ideal natural frequency and calculate

the ideal Shear and Young’s Modulus (G and E respectively).

Ideal Material Calculations:

The mass of the camera lens, cross-sectional area of the shock mounts, and the thickness of the

shock mounts are from the documentation of MSD P09561.

Poisson’s Ratio of Sorbothane is assumed to be the same as similar materials (ie Polyurethane and

Rubber)


If the Poisson’s Ratio was assumed to be 0.5:

A marginal material solution can be found using the marginal natural frequency that was previously

found.

If the Poisson’s Ratio was assumed to be 0.5:

Conclusion:

The ideal material for this vibration system would have a Young’s Modulus between 225 [psi] and

270 [psi]. The strongest of the materials listed on the Sorbothane website (Shore 70 oo) has a listed

Young’s Modulus of 206 [psi], it is possible that this material would be strong enough to reduce the

camera lens displacement during system operation, however a stronger material would have a

greater effect. The proposed solution is to use the Shore 40A (Shore 75 oo) rubber material found

the McMaster-Carr website.


Graph:

Thi

s graph shows the Dynamic Young’s Modulus for Sorbothane 30 oo, 50 oo, and 70 oo plotted with

the frequencies at which those Moduli occur. There is a linear trend line plotted along the natural

frequencies of the Sorbothane. The vertical line at 7.9 Hz represents the Ideal natural frequency of

the material used as a solution. The red shaded areas represent the natural frequencies and

Dynamic Young’s Modulus at which a material won’t properly dampen the system.


Impact Foam System

Specification:

Camera and components must survive a 20 G crash.

System must be lightweight.

Assumptions:

Free fall with no drag or aerodynamic forces (lift).

Ground surface is soil and grass (allows for greater travel on impact).

Theory:

G force is a measurement of acceleration given by the following formula:

Gg

a

where a is the acceleration in feet per second squared and g is the acceleration due to gravity which

is 32.174 feet per second squared.

If the object were to fall from this maximum height the velocity of the object just before it hits the

ground surface can be found using the following equation:

gyVf 2

The acceleration can then be found using the following equation:

x

Vfa

2

2

Where x is the distance is the object travels once it hits the ground surface (crush zone). The

greater the distance, the slower the acceleration. The G force felt by the object can then be found

using the first formula.


The pressure can be found using the following formula:

Area

onAcceleratiMass

Area

Forceessure

*Pr

This pressure force takes into account the mass and area of the objects surface that is hitting the

ground surface. This pressure is used to pick out a foam material that will allow the object to

decelerate over a longer distance. The object then experiences a smaller acceleration and has a

higher chance of surviving the impact.

Experiment:

Two densities of foam were tested to determine the effect of foam type on the crush zone created.

Large celled foam and small celled foam were tested from 1 to 6 feet and the results are as follows:

Foam Impact Test

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 1 2 3 4 5 6 7

Drop Height (feet)

Inc

he

s o

f P

en

etr

ati

on

Small Celled Foam

Large Celled Foam

The small celled foam had less penetration which would allow for maximum crush zone for large

impacts, but would not crush under lower impacts. The opposite is true for the large celled foam.

The small cell foam tended to crack to absorb the energy rather than impact, which would pose a

problem in a realistic scenario.


Analysis:

The maximum height of UAV C is 400 ft. If the camera were to fall from this maximum height the

final velocity is 160.435 feet per second. A more realistic drop would be from a tumble or failure to

land properly. This height is estimated as a maximum10 foot drop. The velocity in this case from 10

ft is 25.37 feet per second.

The G force acceleration from maximum (400 ft) drop with a crush zone of 4 inches is 100 Gs. The

more likely scenario of a drop from 10 ft with a crush zone of 2 inches has an acceleration of 5 G’s. If

the crush zone is .5 inches, then the acceleration is 20 G’s. So the minimum distance the camera

would have to travel to feel a 20 G acceleration is 5 inches.

Each component has a shock rating that it is manufactured to survive up to. The camera has a shock

resistance of 70 G’s and the circuit boards around 50 G’s. Knowing this, the camera and components

will already survive a 20 G crash without any protection. From 400 feet it can be calculated that it

would take an 8 inches crush zone to allow the components to survive the impact. This crush zone

includes the balsawood frame of the aircraft, the indentation in the ground and the addition of foam

padding.

This addition of padding will allow the components the maximum survivability from taller heights.

The components will also not be falling like a rock as assumed in these worst case scenarios. There

will be a drag force from the air slowing it down and unless the plan is completely destroyed, a

small lift force will slow the fall as well.

To select a foam material the pressure forces were calculated on the camera component. At 20 G’s

the pressure on the camera would be 1.72 psi and at 100 G’s the pressure would be 8.60 psi. Foam

was selected on these pressure values. A combination of easy to crush foam and harder foam will

allow the camera to be protected from high and low impacts.

Results:

Foam Choices:

Neoprene, Firmness (25% deflection) = 2-5psi

Polyurethane, Firmness (25% deflection) = .57psi


Frame System

Background:

The frame design that was chosen was designed to withstand an impact from the maximum flight

altitude. A partition was created to divide the frame into two sections. One section will contain the

camera lens and the other section will contain the camera’s components. This partition will protect

the camera lens from potential damage cause by the components assembly in the event of a crash.

The top of the frame is designed to open and close to allow easy installation of all components. The

frame material selected is Al 6061-T651. This has a yield strength of 40 ksi.

Figure 1: Frame Design

Analysis:

The worst case scenario force was calculated to be 1500 pounds. This was applied to the frame in

two different ways. In the first case, the 1500 pound load was applied to the side face of the frame.

This yielded a minimum factor of safety of 1.2, a maximum displacement of 0.06793 inches, and a

maximum stress of 33 ksi. These results are shown in Figures 2-4.

Figure 2: Factor of Safety Results with 1500 lb load on entire face


Figure 3: Displacement results with 1500 lb load on entire face

Figure 4: Stress results with 1500 lb load on entire face

The second case was applying the same maximum force of 1500 lb on one edge of the frame system.

The 1500 lb load was applied at 45°. This case resulted in a factor of safety of 1.0, a maximum

displacement of 0.12 inches, and a maximum stress of 33.3 ksi. These results are shown in Figures

5-7.

Figure 5: Factor of Safety results with 1500 lb load applied at 45°


Figure 6: Maximum displacement results with 1500 lb load applied at 45°

Figure 7: Stress results with 1500 lb load applied at 45°


Details of Frame:

All faces of the frame will be CNC machined. These pieces will then be welded together. The top

portion will be connected with hinges.

Material: Al 6061-T651

Dimensions: 15.75” x 5.75” x 5”

Weight: 2.54 lb


Risk Assessment


Areas of Concern

Stabilization System:

o Material chosen too stiff not allowing proper dampening of vibration

o Material chosen too soft allowing a larger camera displacement then desired

o Testing equipment availability

Impact Foam System:

o Foam material properties vague

o Proper protection of camera: soft vs hard foam

Frame System:

o Long lead time on CNC machine

o Extra time to make prototype frame

Bill of Materials


MSD II Action Items

Build Phase

Order Parts and Materials

Machine frame parts

Weld frame parts

Build Frame Structure Prototype

Build Frame Structure

Assemble foam

Change dampeners on existing vibration isolation system

Build vibration test stand

Test Phase

Create Final Test Plan

Vibration Testing

Impact Testing

Interface Testing

Total System Specs Testing

Presentation

Technical Paper

Make MSD Poster

Make presentation for Imagine RIT

Final Project Review

EDGE website

Miscellaneous

Create Meeting Schedule

Regular Updates with guide


Appendix A:

P11562 MIS Frame and Stabilization Module Preliminary Test Plan

1. MSD I: WKS 8-10 PRELIMINARY TEST PLAN

1.1. Sub-Systems

Major Sub-Systems/ Features/ Function

1 Interface

2 Total System Specifications

3 Impact Protection

4 Vibration Dampening

1.2. Test Results

Interface Test

Subsystem: Interface

Date Completed:_________________

Performed By:___________________

Tested By:______________________

Engr.

Spec.

#

Specification (description) Unit of

Measure

Marginal

Value

Ideal

Value Comments/Status

ES2

Interfaces – All parts must

interface with each other as

well as the camera system

and UAV

G 20 >20


Total System Specifications Test

Subsystem: Total System Performance


Performed By:___________________

Tested By:______________________

Engr.

Spec.

#

Specification

(description)

Unit of

Measure

Marginal

Value Ideal Value Comments/Status

ES3

Total System Weight –

System must be less

than 15 pounds

lb 15 <15

ES4

Total System Volume –

System must fit inside

UAV and allow room

for camera system

inch 15.75x5.75x5 15.75x5.75x5

ES5

Withstand Atmospheric

Conditions – System

needs to withstand

varied atmospheric

conditions

Degrees

F -20 to 120 <-20 to >120

Impact Survival Test

Subsystem: Impact Protection


Performed By:___________________

Tested By:______________________

Engr.

Spec.

#


Measure

Marginal

Value

Ideal


ES6

Impact Isolation - The

frame and components

must survive a 20 G or

greater shock.

G 20 >20


Vibration Test

Subsystem: Vibration Dampening


Performed By:___________________

Tested By:______________________

Engr.

Spec.

#


Measure

Marginal

Value

Ideal


ES1 Mechanical Isolation Hz >75 >50

1.3. Test Equipment

Engr.

Spec. # Instrumentation or equipment not available (description)

ES1 Vibrations Lab Computer and Stabilization block

ES2

ES3

ES4

ES5 Oven, Freezer

ES6


Interface Test

Date Completed:______________

Performed by:________________

Specifications Tested

Engr.

Spec.

#


Measure

Marginal

Value

Ideal


ES2 Interfaces G 20 >20

All parts must interface with

each other as well as the

camera system and UAV

Revision History

Revision Description Date

1

Document Created

2/8/2011

Equipment

_____Assembled Frame (prototype)

_____ Stabilization Assembly

_____Components Assembly

_____UAV (with wing removed)

_____Layered Foam Material


Sections

Part 1 Component Interface

Part 2 UAV Interface

Part 1 Component Interface


Performed by:________________

_____1. Place Stabilization Assembly into Frame and verify proper fit.

_____2. Place Components Assembly into Frame and verify extra room provided on all sides.

_____3. Remove Components Assembly.

_____4. Place layers of foam into frame.

_____5. Place Components Assembly into frame.

_____6. Place foam around sides and on top of masses.

_____7. Verify foam fits properly around Components Assembly and Stabilization System.

_____8. Close lid and ensure it is properly latched.

Sign off on section before continuing:__________________________________________


Part 2 UAV Interface


Performed by:________________

_____1. Place latched frame assembly into UAV.

_____2. Place foam around sides and on top to make frame fit tight.

_____3. Verify proper fit of the frame.



Impact Survival Test


Performed by:________________


Engr.

Spec. #

Specification

(description)

Unit of

Measure

Marginal

Value

Ideal


ES6

Impact Isolation

G 20 >20

The frame and components must

survive a 20 G or greater shock.

Revision History


1

Document Created

2/6/2011

Equipment


_____Accelerometers

_____ Rectangular Mass1 - represent components box

_____Rectangular Mass2 - represent camera and stabilization platform



Sections

Part 1 Frame Impact Survival

Part 1 Frame Impact Survival


Performed by:________________

_____1. Place layers of foam into frame.

_____2. Place masses with accelerometers attached into frame.

_____3. Place foam around sides and on top of masses.

_____4. Replace lid and secure.

_____5. Place accelerometers on frame.

_____6. Drop starting from lowest height and record in chart.

_____7. Verify that components are below g force rating at 20 G impact.


Height (ft) G force on Box G force on Mass1 G force on Mass2

1

2

3

4

5

6

7

8

9

10


Height at which 20 G is felt on box


Max height for component survival




Total System Specifications Test


Performed by:________________


Engr.

Spec.

#

Specification

(description)

Unit of

Measure

Marginal

Value Ideal Value Comments/Status

ES3

Total System Weight –

System must be less

than 15 pounds

lb 15 <15

ES4

Total System Volume –

System must fit inside

UAV and allow room

for camera system

inch 15.75x5.75x5 15.75x5.75x5

ES5

Withstand Atmospheric

Conditions – System

needs to withstand

varied atmospheric

conditions

Degrees

F -20 to 120 <-20 to >120

Revision History


1

Document Created

2/9/2011


Equipment



_____Components Assembly


Sections

Part 1- Total System Weight

Part 2 - Total System Volume

Part 3 - Withstand Atmospheric Conditions

Part 1 - Total System Weight


Performed by:________________

_____1. Place Stabilization Assembly, Components Assembly, and Foam Material into Frame.

_____2. Place the Assembly on scale and verify that the total weight is less than or equal to 15 pounds.


Part 2 - Total System Volume


Performed by:________________


_____1. Measure the length, width, and height of the Frame Assembly.

_____2. Verify that the Frame is 15.75" x 5.75" x 5".


Part 3 - Withstand Atmospheric Conditions


Performed by:________________

_____1. Place Frame Assembly into oven and heat up to 120°F.

_____2. Verify that the Frame Assembly has not deformed.

_____3. Use freezer to bring the Frame Assembly to -20°F.

_____4. Verify that the Frame Assembly has not deformed.



Mechanical Isolation Test


Performed by:________________


Engr.

Spec.

#


Measure

Marginal

Value

Ideal


ES1 Mechanical Isolation Hz >75 >50

Revision History


1

Document Created

2/9/2011

Equipment

_____UAV C Engine


_____UAV C Propeller

_____UAV C Batteries and Electrical Wiring

_____Vibrations Testing Stabilization block

_____Interface 1 (UAV C Engine to Vibrations Testing Stabilization block)

_____Interface 2 (Stabilization Assembly to Vibrations Testing Stabilization block)


_____Accelerometers (3)

_____Accelerometer Software (On computer in Vibrations Lab)

_____Rubber Shore 40A Shock Mounts

Sections

Part 1 UAV C Engine / Propeller Vibrations Test

Part 2 Stabilization Vibrations Test

Part 1 UAV C Engine / Propeller Vibrations Test


Performed by:________________

_____1. Design an interface to properly mount the UAV C Engine to the Testing Equipment (Interface 1)

_____2. Build Interface 1

_____3. Attach the UAV C Engine to the Testing Equipment

_____4. Attach the accelerometers to UAV C Engine

_____5. Attach Power Supply (Batteries) to UAV C Engine

_____6. Run UAV C Engine from rest to cruise velocity

_____7. Record accelerometer data

_____8. Determine magnitudes of critical vibration frequencies



Part 2 Stabilization Vibrations Test


Performed by:________________

_____1. Design an interface to properly mount the Stabilization Assembly to the Testing Equipment

(Interface 2)

_____2. Build Interface 2

_____3. Attach Stabilization Assembly to the Testing Equipment

_____4. Attach Accelerometers to Camera Lens substitute

_____5. Simulate critical magnitudes and vibration frequencies

_____6. Record accelerometer data

_____7. Determine effectiveness of new shock mounts



Appendix B: Works Cited

“Sorbothane Material Properties”. Sorbothane.com. 2011. Feb 9 2011.

<http://www.sorbothane.com/material-properties.php>.

“P09561: Visible Spectrum Imaging System”. edge.rit.edu. May 16 2009. Feb 9 2011.

<https://edge.rit.edu/content/P09561/public/Home>.

“McMaster-Carr”. www.mcmaster.com. Feb 9 2011. Feb 9 2011.

<http://www.mcmaster.com/#>.

“Speedy Metals”. www.speedymetals.com. 2009. Feb 9 2011.

<http://www.speedymetals.com/>.


https://edge.rit.edu/content/P09561/public/Home

http://www.mcmaster.com/

http://www.speedymetals.com/

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