Presentation on theme: "Camera Protection using Sun Sensor-Shutter Device 22-July 2008 Jay Jiaquan Zheng Mentor: Dennis Douglas."— Presentation transcript:
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 – 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 ……There’s a reason they tell you not to look into the sun! Brain – Sun Sensor Eyelid – Solar Shutter Eye – Camera Camera Sun Sensor Solar Shutter
SS boresighted to telescope Shutter mounted on back of telescope Can be apply to ALL telescopes Sun Sensor 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. Shutter Preliminary Design Locates Sun Sensor & Shutter Device On A Telescope Telescope Housing front back
ADC (Analog Digital Converter) Microprocessor 2 Overall System Diagram Links Functionalities Of COTS And Custom Components Slider –Crank Mechanism Motor Convert to Mechanical Power (Torque) Lid 3 OPM Convert to Electrical Power (voltage) OPD Pinhole 1 Detector Optical Power Input (sun light) COTS = Commercial Off The Shelf Components
SolidWorks Modeling Suggests Sun Sensor (Ray-Box) Design Meets Specifications Housing – Adjustable : Threshold: 10 o – 60 o – Determine by: Distance: Detector – Pinhole Complete CAD Assembly Constructed in SolidWorks Back Mount Detector Housing Pinhole Extender Thread pattern
Ray-Box Geometry Allows For Multiple Solar Exclusion Angles To Be Set L θ R r ab Geometric Relationship: θ Sun Position 1 Sun Position 2 L R r detector pinhole
Adjusting Length Of Sun Sensor Corresponds To Specific Solar Threshold Angle Detector Radius, R : mm Pinhole Radius, r : mm θ (o)l (mm)θ (o)l (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 Red area represents Threshold Angle = Solar Exclusion Zone OPM detector Voltage reading Sun Positions 30 o 0 25 mm Optical Power Meter outputs voltage depends on incident light summer winter
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 Lid Ball Slide Motor Rack & Pinion Slider-Crank If it takes 10 seconds for your eyelid to close when looking directly at the Sun…
Slider-Crank Mechanism Synthesized based on Position, Velocity & Force/Stress Analysis. Rack & Pinion Assembly Designed using Dynamic Analysis. Motor Selected based on Max Torque. Superimposing All Major Components Allows For Analysis Of Effective Shutter Design Ball Slide Selected based on sliding distance.
Position Analysis & Motion Of Slider-Crank Modeled Using Matlab Programming Lid slider
Velocity Analysis Of Slider-Crank Generates Relationship Between Lid And Slider Velocity o b c a fix O A B C Note: All terms defined in Position Analysis except slider velocity, or v s. Velocity Polygon Lid Slider
Dynamic Analysis Performed On Rack & Pinion System Based On Kinetic Energy Theory T – motor torque x – rack displacement R – gear radius I – gear inertiam – rack mass Equivalence Inertia Dynamics Model R I x, v s T m
Customer Specification Designer Input Calculation Output Purchase Parts Linkage Factor Safety Linkage Factor Safety Response Time Response Time Maximum Allowable Pressure Maximum Allowable Pressure Slider Acceleration Slider Acceleration Slider Velocity Slider Velocity Lid Velocity Lid Velocity Motor Slide Slide Gears Dimension Position Material nLgLg P T R,I a dvsvs (x,y,z) vlvl Customer $ Block Diagram Demonstrates Design Process And Components Specifications of Shutter Device
GUI Interface Allows User Input To Optimize Design Based On System Parameters and Variables
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...
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 ) 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 ) and from the University of Hawaii.