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Space Solar Power
Thomas LynchBoeing
Sun Tower Concept15 kM bed length3 GW output beam< 5 cents/kWHr$125B Fab Estimate
Microwave beam to earth mounted “Rectenna”
Introduction
Laser Beam to Existing Photovoltaic Solar Array
Introduction
1. Concentrator focuses sunlight on spacebased PV array
2. PV array powers laser diode
3. Laser diode pumps fibers
6. DC electricityis converted to AC
7. Power is distributed to consumers
4. Light from fibers is fed to optics and transmitted to Earth
5. Terrestrial PV receiver array converts sunlight to DC electricity
Satellite Concept of Operation
•Two robots placed symmetrically on transmitter’s frontside
•Robots move on a rail connected at perimeter and center
Robot assembles and repairs transmitter modules
83,841,250 Radiating Elements2.141 GW Radiated
Transmitter Face and RobotMicrowave (5.8GHz)
Solar Cell Efficiency vs Wavelength
Example: Laser Diode Array achieves 40% with LASER SSP & Photovoltaic ground Array
1kW/m2 ~ Sun on Earth
Typical earth mounted solar array has 14% efficiency
Visible Light(reference)
10SSP Economic & Market Analysis Team
Economic and Market Factors General Cost Findings
– For 1996, U.S.• Generating costs for new plants averaged about 3.8 ¢/kWh (EIA, 1997)
– For ~ 2020, U.S.• A “reference case” for generation costs in 2020 is ~ 3.2 to 3.3 ¢/kWh
– World Bank experts suggested an average generating cost, ~ 2020, for rapidly growing economics, of ~ 5.5 ¢/kWh
Under following conditions:• Deregulation of foreign electric power markets • Resource inputs trade in a world market at world prices• Globalization of investment and technology • Interfuel competition holds costs down
14SSP Economic & Market Analysis Team
Preliminary Observations Market
1,738
6951,043
China OECD Other Developing
World Energy Prospects to 2020, IEA, 1998
Growth In Electric Capacity Supply
1995 2020 (GW)
SPG Pointing Accuracy, Structural Control Trades
• Pointing– Off pointing : % of capture (2 degrees of control)– Surface accuracy requires active control – 12o for PV concentrator cells– Each concentrator needs its own control– Disturbance while pointing may impact WPT– Station keeping
• Lifetime (40 yrs)– Rotating machinery– Concentrator Materials– Actuator control
Pat George
• SSP must be managed by robotics– Installation – Perform maintenance– Affect repairs
• All are imperative to achieve cost objective of < 5 cents per kWHour
Robotics
LEMURLegged Excursion Mechanical Utility Robot
LEMURA new type of autonomous npod walker called LEMUR has been developed for assembly, inspection, and maintenance. This robot demonstrates multimode operations (mobility, inspection, and manipulation) with a modular and multifunctional toolset.
LEMUR Configuration
4 DOF Hex Driver Leg
4 DOF Gripper Leg w/ inline camera (Palmcam) 3 DOF Gripper Leg
Stereo Cameras
– Demonstrated fine manipulation and tool based operations
– Examined payload identification methods
– Implemented fiducial markers for encoding payload identification, orientation, and characteristics
– Performed visual inspection of payloads and robots
LEMURLegged Excursion Mechanical Utility Robot
Threefingered manipulator with integrated camera optics
Hex driver with retractable foot
• Accomplishments– Designed and integrated LEMUR mobile
platform– Developed a threefingered manipulator
with compliant grasp adjustment for manipulation of fine/delicate payloads
– Developed a hex driver endeffector with retractable foot
– Developed a miniature macroscopic imaging camera (Palmcam) for integration into grasping manipulator
– Developed algorithms and computer code for stereo vision and pattern recognition using wavelet decomposition of fiducials
– Demonstrated visual object and selfinspection using the Palmcam
• Current Work– Developing software for autonomous
navigation, inspection, and manipulation of target
Hyper Redundant Intelligent SystemsDescription•Develop small, identical robotic elements that can accomplish tasks collectively that are well beyond the capabilities of its individual members.
•Approach•Utilize serpentine chain of linkages with integrated computing, sensing, and power as testbed for cooperative robotics executing construction, inspection, and maintenance
ParticipantsNASA Haith, Wright, Loch, ThomasCMU Howie ChosetIndustry Randy Sargent (Newton Labs)
Technology Elements• Mechanism Configuration: advanced actuators,
packaging, lightweight structure, power, biomimetic skin
• Single Robot Control: force and redundancy control strategies, communication, simulation & modelling of hyperredundant systems
• Cooperative Robot Control: Autonomy;Mobility planning in complex structures, payload strategies, data sharing/sensing
Hyper Redundant Intelligent Systems
• Benefits– Highly Redundant (> 7 DOF) serial
link manipulator chains– Capable of long reach into highly
constrained spaces (trusses, frames)
– Capable of prehensile grasping, limbless locomotion
– Redundant to multiple joint failures
• Research Challenges– Path and motion planning to
arbitrary locations in a complex 3D structure using generalized voronoi graph search
Actual system “flight proven” through successful mission operations
Actual system completed and “flight qualified” through test and demonstration (Ground or Flight)
System prototype demonstration in a space environment
System/subsystem model or prototype demonstration in a relevant environment (Ground or Space)
Component and/or breadboard validation in relevant environment
Component and/or breadboard validation in laboratory environment
Analytical and experimental critical function and/or characteristic proofofconcept
Technology concept and/or application formulated
Basic principles observed and reported
System Test, Launch & Operations
System/Subsystem Development
Technology Demonstration
Technology Development
Research to Prove Feasibility
Basic Technology Research
TRL 9
TRL 8
TRL 7
TRL 6TRL 6
TRL 5TRL 5
TRL 4
TRL 3
TRL 2
TRL 1
Assessing Technology Readiness Levels