Camera protection using sun sensor shutter device
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Camera Protection using Sun Sensor-Shutter Device. 22-July 2008 Jay Jiaquan Zheng. Mentor: Dennis Douglas. Overview of Sun Sensor – Shutter Device. Analogy: Human Eye & Camera Purpose Of Sun Sensor – Shutter Device Introduction of Sun Sensor – Shutter Device System Diagram

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Camera Protection using Sun Sensor-Shutter Device

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Camera protection using sun sensor shutter device

Camera Protection using Sun Sensor-Shutter Device

22-July 2008

Jay Jiaquan Zheng

Mentor: Dennis Douglas


Overview of sun sensor shutter device

Overview of Sun Sensor – Shutter Device

  • Analogy: Human Eye & Camera

    • Purpose Of Sun Sensor – Shutter Device

  • Introduction of Sun Sensor – Shutter Device

    • System Diagram

    • Overall Preliminary Design

  • Detailed Design of System

    • Sun Sensor

    • Electrical Components

    • Solar Shutter

  • Summary & Path Forward

    • Has design met specification

    • Future goals


The human eye provides a conceptual basis for a solar sun sensor

The Human Eye Provides A Conceptual Basis For A Solar Sun Sensor

  • Brain – Sun Sensor

  • Eyelid – Solar Shutter

  • Eye – Camera

Sun Sensor

Solar Shutter

Camera

……There’s a reason they tell you not to look into the sun!


Camera protection using sun sensor shutter device

Preliminary Design Locates Sun Sensor & Shutter Device On A Telescope

Shutter

Sun Sensor

front

Telescope

Housing

back

SS Design:

Extend/Retractable

Ray-Box, pinhole in

front, optical

detector in the back.

Shutter Design:

Slider-Crank using

Rack & Pinion

assembly driven by

a Micromotor.

  • SS boresighted to telescope

  • Shutter mounted on back of telescope

  • Can be apply to ALL telescopes


Camera protection using sun sensor shutter device

Optical Power Input

(sun light)

Detector

OPD

OPM

Convert to

Electrical

Power

(voltage)

ADC

(Analog Digital

Converter)

Pinhole

1

Convert to

Mechanical

Power

(Torque)

Slider –Crank Mechanism

Microprocessor

2

Lid

Motor

3

Overall System Diagram Links Functionalities

Of COTS And Custom Components

COTS = Commercial Off The Shelf Components


Solidworks modeling suggests sun sensor ray box design meets specifications

SolidWorks Modeling Suggests Sun Sensor (Ray-Box) Design Meets Specifications

Detector

Housing

Back

Mount

Pinhole

Extender

Thread pattern

  • Housing

    • Adjustable : Threshold: 10o – 60o

    • Determine by: Distance: Detector – Pinhole

  • Complete CAD Assembly Constructed in SolidWorks


Ray box geometry allows for multiple solar exclusion angles to be set

Ray-Box Geometry Allows For Multiple Solar Exclusion Angles To Be Set

pinhole

Sun Position 1

detector

θ

Sun Position 2

Geometric Relationship:

a

b

r

R

L

R

θ

r

L


Adjusting length of sun sensor corresponds to specific solar threshold angle

Adjusting Length Of Sun Sensor Corresponds To Specific Solar Threshold Angle

  • Detector Radius,

  • R : 5.207 mm

  • Pinhole Radius,

  • r : 1.500 mm

  • Threshold Angle

  • -Given by Optical Straylight Analysis

  • Cameras can be damage

  • when reached


Detecting threshold angle using voltage curve generated by optical power meter

Detecting Threshold Angle Using Voltage Curve Generated By Optical Power Meter

  • Red area represents

  • Threshold Angle = Solar Exclusion Zone

Optical Power Meter outputs voltage depends on incident light

30o

summer

detector

25

mm

Voltage reading

winter

0

OPM

Sun Positions


Computing unit analysis signal from sun sensor effectively controls shutter device

Computing Unit Analysis Signal From Sun Sensor Effectively Controls Shutter Device

  • Analog to Digital Converter (ADC)

    • OPM outputs analog signals,

      Microprocessor could only

      read digital signals.

  • Microprocessor

    • Controls motion of motor in

      Shutter device


Solidworks modeling of shutter provides spatial tolerances structural properties

SolidWorks Modeling Of Shutter Provides Spatial Tolerances & Structural Properties

Lid

Motor

Slider-Crank

Rack & Pinion

Ball Slide

If it takes 10 seconds for your eyelid to close when looking directly at the Sun…


Camera protection using sun sensor shutter device

Rack & Pinion Assembly

Slider-Crank Mechanism

Designed using Dynamic Analysis.

Ball Slide

Motor

  • Synthesized based on Position, Velocity & Force/Stress Analysis.

  • Selected based

  • on Max Torque.

Selected based

on sliding distance.

Superimposing All Major Components Allows For Analysis Of Effective Shutter Design


Position analysis motion of slider crank modeled using matlab programming

Position Analysis & Motion Of Slider-Crank Modeled Using Matlab Programming

Lid

slider


Velocity analysis of slider crank generates relationship between lid and slider velocity

Velocity Analysis Of Slider-Crank Generates Relationship Between Lid And Slider Velocity

o

c

A

b

B

C

fix

O

a

Lid

Velocity Polygon

Slider

Note: All terms defined in Position Analysis except slider velocity , or vs .


Dynamic analysis performed on rack pinion system based on kinetic energy theory

Dynamic Analysis Performed On Rack & Pinion System Based On Kinetic Energy Theory

I

R

T

x, vs

m

T – motor torque x – rack displacement

R – gear radius I – gear inertiam – rack mass

  • Equivalence Inertia

  • Dynamics Model


Camera protection using sun sensor shutter device

Motor

Linkage

Factor

Safety

Maximum

Allowable

Pressure

P

n

Lg

T

Gears

R,I

$

Customer

Slider

Acceleration

(x,y,z)

a

Response

Time

Lid

Velocity

vl

vs

Slider

Velocity

d

Slide

Block Diagram Demonstrates Design Process

And Components Specifications of Shutter Device

Dimension

Material

Position

Calculation Output

Purchase Parts

Designer Input

Customer Specification


Camera protection using sun sensor shutter device

GUI Interface Allows User Input To Optimize

Design Based On System Parameters and Variables


Summary and path forward

Summary and Path Forward

Effective Sun Sensor-Shutter Device can be constructed using Commercial Off The Shelf and custom components.

Modeling suggests this device will have a time response of 0.4 seconds and perform safely.

Future goal is to determine costs of COTS and custom equipments and integration plan...


Camera protection using sun sensor shutter device

Acknowledgement

Dennis Douglas,

Daron Nishimoto, Riki Maeda, Chet Jonston

Lani LeBron, Scott Seagroves,

Lynne Raschke, Lisa Hunter

The Akamai Internship Program is funded by the Center for Adaptive Optics through its National Science Foundation Science and Technology Center grant (#AST-987683) and by grants to the Akamai Workforce Initiative from the National Science Foundation and Air Force Office of Scientific Research (both administered by NSF, #AST-0710699) and from the University of Hawaii.


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