Experimental CDIO Capstone Course 1 S T U F F a t e l l i t e e s t b e d n t e t h e r e d o r m a t i o n l y i n g f o r

2 Trade Analysis & Requirements Review The STUFF Experimental CDIO Capstone Course February 25, 1999

Experimental CDIO Capstone Course GPB, AC, JAW3 Presentation Outline Program Objective and Motivations Subsystems –Propulsion –Power and Avionics –Metrology –Communications and Software –Structures Design Concept Presentation Conclusions

Experimental CDIO Capstone Course GPB, AC, JAW4 Program Objective To develop a testbed that demonstrates formation flying algorithms between multiple autonomous satellites with six degrees of freedom, in a microgravity environment

Experimental CDIO Capstone Course GPB, AC, JAW5 Motivation Demand for spacecraft to perform autonomous formation flying missions is increasing –Smaller –Simpler –Cheaper Current testbeds do not allow full modeling of dynamics related to formation flying

Experimental CDIO Capstone Course GPB, AC, JAW6 Justification for Flight

Experimental CDIO Capstone Course GPB, AC, DRF7 Specific Science Objectives 1. Develop a set of multiple distinct satellites that interact to maintain commanded position, orientation, and direction 2. Allow for the interchange of control algorithms, data acquisition and analysis, and a truth measure 3. Demonstrate key formation flying maneuvers 4. Demonstrate autonomy and status reporting 5. Ensure the implementation of control algorithms is adaptable to future formation flying missions 6. Allow for testbed operation on KC-135, Shuttle middeck, and ISS

Experimental CDIO Capstone Course GPB, AC, DRF8 Engineering Science Requirements 1. To develop a set of satellites which interact to maintain commanded position, orientation and direction –Satellites require translational, rotational, and attitude control capabilities –Each satellite must have its own propulsion, avionics, software, power, communication, and GNC systems –Satellites must be able to maintain communication with each other –Satellites must be able to recover from small disturbances –The array should consist of at least three satellites

Experimental CDIO Capstone Course GPB, AC, DRF9 Engineering Science Requirements (cont.) 2. Allow for the interchange of control algorithms, data acquisition and analysis, and a truth measure –Satellites must be able to execute uploaded control algorithms –Satellites must be able to acquire and analyze metrology data –Ground station (non-satellite testbed components) must provide an independent verification of metrology data –Ground station must store downloaded data

Experimental CDIO Capstone Course GPB, AC, DRF10 Engineering Science Requirements (cont.) 3. Demonstrate key formation flying maneuvers –Array Capture and Initialization Satellites should perform self-diagnostic on power up Satellites must determine absolute and relative positions –Static & Dynamic Array maintenance Satellites must maintain commanded orientations and positions –Array Repositioning Satellites must be able to move to new commanded orientations and positions –Fault Detection and Recovery Satellites must detect failures and compensate for them

Experimental CDIO Capstone Course GPB, AC, DRF11 Engineering Science Requirements (cont.) 4. Demonstrate autonomy and status reporting –Each satellite must be able to complete its maneuvers without ground station or human input –Each satellite must be able to recognize and report any failure of its own systems –Array must compensate for failure of any other satellite

Experimental CDIO Capstone Course GPB, AC, DRF12 Engineering Science Requirements (cont.) 5. Ensure the implementation of control algorithms is adaptable to future formation flying missions –Testbed subsystems should mimic actual satellite subsytems in order to allow control algorithms to be adaptable to future missions –Testbed capabilities should be analogous to actual satellite capabilities

Experimental CDIO Capstone Course GPB, AC, DRF13 Engineering Science Requirements (cont.) 6. Allow for testbed operation on KC-135, Shuttle middeck, and ISS –Ensure all applicable safety requirements are met –Ensure formation flying maneuvers can be executed in available KC-135 Experiment duration must be less than 20 seconds Satellites must be able to survive 2g fall Experiment must initialize in less than 5 seconds Shuttle Middeck / ISS Testbed equipment must fit in middeck locker(s) Testbed equipment must meet weight requirements Satellites must compensate for air currents due to scrubbers Emergency teardown time in 30 minutes

14 Propulsion Dan Feller Presenter

Experimental CDIO Capstone Course GPB, DRF, BMP15 Propulsion Requirements Safety –Non-toxic byproducts –Temperatures not to exceed range (TBD) –Non-touch hazard Propellant –Propellant supply sufficient to last at least 20 seconds. Control –System must provide for 6 DOF –System must provide constant performance throughout flight duration. Thrust –Large ISP (TBD)

Experimental CDIO Capstone Course GPB, DRF, BMP16 Propulsion Options Station Keeping / Attitude –Compressed Gas Highly Traceable, Cost Effective, Off-the-Shelf Components –Fans/Propellers Simple, Cost Effective but... –Micro Engines and Rockets Technology not yet operational Attitude Control –Reaction Wheels large, heavy, large size –Control Moment Gyros (CMGs) large size –Magnetic Torquers large size, long time to develop, large power demand

Experimental CDIO Capstone Course GPB, DRF, BMP17 Propulsion Metrics Safety: –Toxicity –Thermal Hazard –Touch Hazard –Fracture Hazard Impulse Bit (Smallest quanta of thrust) Traceability Cost Efficiency –ISP, Mass ratio –ISP, Volume ratio Power Consumption Ease of Replacement Time to Develop

Experimental CDIO Capstone Course GPB, DRF, BMP18 Propulsion Downselect

Experimental CDIO Capstone Course GPB, DRF, BMP19 Compressed Gas Options CO 2 (Liquid or Gas) –Readily Available, Easy Containment, Adequate Thrust, Toxic N 2 / Air (Liquid or Gas) –High Thrust, Non-Toxic, Difficult Containment Onboard Compressor –Heavy, High Power Consumption, Low Thrust

Experimental CDIO Capstone Course GPB, DRF, BMP20 Compressed Gas Downselect

Experimental CDIO Capstone Course GPB, DRF, BMP21 Propulsion Budget Sub-system demands: –Power: 2W –Volume: 1.5 liter –Mass: 3 kg –Cost: $3000 Sub-system provides: –Thrust: TBD

22 Structures Dan Feller Presenter

Experimental CDIO Capstone Course DAC, AC, DRF, JES23 Structures Requirements Structural integrity –Must survive Shuttle launch and landing loads –Must survive a drop of 4 feet in 2-g Satisfaction of mass and volume constraints –Container requirement Mass: 60lbs = 27kg Dimensions: Max. 9 in. = 22 cm diameter (middeck locker) –Single satellite should be less than 7 kg –Structure should be ~10% of total satellite mass (0.7 kg) –Structure should provide easy accessibility to internal components Must be manufacturable and safe under crew handling

Experimental CDIO Capstone Course DAC, DRF, JES24 Structures Options Shape –Cube –Sphere –Polyhedron Assembly –Truss –Shell (no internal truss) –Hybrid (a truss structure with paneling) Materials –Alloys and metals –Composites –Plastics and polycarbonates

Experimental CDIO Capstone Course DAC, DRF, JES25 Structures Criteria Integrity –Internal and external load carriage Safety –Fracture toughness (structure cannot shatter) –Sharp edges & corners Feasibility –Manufacturing –Internal accessibility –Cost

Experimental CDIO Capstone Course DAC, DRF, JES26 Shape Downselect

Experimental CDIO Capstone Course DAC, DRF, JES27 Assembly Downselect

Experimental CDIO Capstone Course DAC, DRF, JES28 Materials Downselect

Experimental CDIO Capstone Course DAC, DRF, JES29 Structures Budget Mass –TBD, pending estimates of other sub-systems Volume –TBD, but must fit within a STS mid-deck locker, i.e. greatest dimension < 9 in. Cost –TBD, pending allowance notification

30 Power and Avionics Chad Brodel Presenter

Experimental CDIO Capstone Course JAW, SEC31 Power and Avionics Requirements Total power should be approximately 18 W –Total Volts and Amps TBD All hardware must be contained in individual satellite Data storage must be adequate Components must be compatible with KC- 135, Shuttle, and ISS environments System should be traceable to existing satellites

Experimental CDIO Capstone Course JAW, SEC32 Power Distribution

Experimental CDIO Capstone Course JAW, SEC33 Power Options Battery Power –Non-rechargeable batteries Alkaline Carbon Zinc Lithium Silver Oxide Zinc Air Silver Zinc –Rechargeable Nickel Cadmium Nickel Metal Hydride Solar Cells

Experimental CDIO Capstone Course JAW, SEC34 Power Criteria Energy Density –By mass –By volume Size –Weight –Volume Cost Safety Number of Batteries for 12V Operating Temperature Range Capacity Approximate Lifetime

Experimental CDIO Capstone Course JAW, SEC35 Power Downselect

Experimental CDIO Capstone Course JAW, SEC36 Power Recommendations Batteries –Non-rechargeable: Lithium Lifetime approximately 40 minutes –Rechargeable: NiMH Lifetime approximately 30 minutes Solar cells should be considered

Experimental CDIO Capstone Course JAW, SEC37 Power Budget Sub-system demands: –Weight : 300 g –Volume : 250 cm 3 –Cost : TBD Sub-system provides: –18 W –Voltage and Amps TBD

Experimental CDIO Capstone Course JAW, SEC38 Specific Avionics Requirements Sufficient data storage capacity Volume and weight TBD System must be compatible with communications, propulsion, and metrology Low power drain

Experimental CDIO Capstone Course JAW, SEC39 Avionics Options Build Custom Processors Purchase Processors –Commercial Processor Options Tattletale TFX - 11 Tattletale 5F/5F - LCD Spectrum INDY Crickets

40 Communication and Software Chad Brodel Presenter

Experimental CDIO Capstone Course GPB, CSB, SLC41 Communication & Software Satellite to Satellite (STS) –Real time –Send, receive, and temporarily store data –Compatible with KC-135 / Shuttle systems –Must be traceable to existing satellite technology Satellite to Ground (STG) –Does not have to be real time –Data must be recorded for post-flight analysis –Must be compatible with KC-135 / Shuttle systems Communication Requirements:

Experimental CDIO Capstone Course GPB, CSB, SLC42 Software Requirements Software is the interface between input (metrology) and output (propulsion) Requirements : –Must have common programming language –Must be flexible to allow execution of complex maneuvers –Must develop efficient code compiling techniques

Experimental CDIO Capstone Course GPB, CSB, SLC43 Communication Methodology Options All equal authority –Satellites interact to decide how to execute array maneuver Master / Slave –One satellite gives commands to all others Hierarchy / Command Chain –Satellites ranked in authority –Easy command transition in case of failure

Experimental CDIO Capstone Course GPB, CSB, SLC44 Communication Methodology Selection Hierarchy / Command chain ensures no confusion –Satellites numbered 1-3: one control stream –No. 1 Satellite Receives control algorithm from ground Determines each satellite’s position in array Sends commands to other satellites Sends own health status info to ground –Other Satellites Communicate position, velocity and acceleration data to No. 1 Sends own health status data to ground If No. 1 fails, each satellite will shift up in hierarchy

Experimental CDIO Capstone Course GPB, CSB, SLC45 Data Transfer Options Download Data: –Continuously Larger power requirement Uses up bandwidth –Post Flight Possibility of losing on-board data Long download time Larger on-board memory cache required –At regular intervals Efficient combination of options Our recommendation

Experimental CDIO Capstone Course GPB, CSB, SLC46 Communication Downselect

Experimental CDIO Capstone Course GPB, CSB, SLC47 Communication Hardware Selection Best Option (STS, STG): RF –Excellent range –Low power requirement –Reasonable bandwidth and accuracy –Single sensor –Cost effective –Possibility of interference on KC-135, Shuttle middeck

Experimental CDIO Capstone Course GPB, CSB, SLC48 Budgets Constraints Power –Communications sensors and receivers ~ 2 Watts each (1 RF STG and 1 RF STS per satellite) Mass –Communication sensors and receivers ~ 8 grams per satellite Volume –Sensors relatively flat / surface mounted (small)

49 Metrology Fernando Perez Presenter

Experimental CDIO Capstone Course AC, SYC, SLJ, FP50 Metrology Overview Two subsystems –Navigation metrology Real-time position and attitude determination On-board navigation system Accurate –Truth measure Verification of position and attitude Probably some sort of off-board camera or ranging system

Experimental CDIO Capstone Course AC, SYC, SLJ, FP51 Navigation Metrology Requirements Real time--10 Hz Accuracy –Position to 1 cm (TBR) –Attitude to 1º (TBR) Must meet space shuttle and KC-135 interface, interference, & safety requirements Setup in 20 minutes (TBR) Interface with other subsystems –Communications –Avionics –Power Onboard = 2 W (TBR) Off-board = 10 W (TBR) –Structures Mass = 0.3 kg (TBR) Volume = 20 mL (TBR)

Experimental CDIO Capstone Course AC, SYC, SLJ, FP52 Navigation Metrology Options Position –IR/Ultrasound –Ultrasonic Ranging –Gyros/ Accelerometers –Synchronized clock/RF/IR Attitude –Gyros/ Accelerometers –IR/Ultrasound –Pure IR

Experimental CDIO Capstone Course AC, SYC, SLJ, FP53 Navigation Metrology Criteria Metrics –Complexity –Cost –Accuracy Constraints –Onboard Power –Volume –Real time –Mass –Safety –Interference

Experimental CDIO Capstone Course AC, SYC, SLJ, FP54 Navigation Metrology Downselect Note: Power, Volume, Safety, and Interference were considered on a binary scale and are listed as constraints where the subsystem requirements were not met

Experimental CDIO Capstone Course AC, SYC, SLJ, FP55 Truth Measure Metrology Requirements Accuracy –Position to 1 cm (TBR) –Attitude to 1º (TBR) Must meet space shuttle and KC-135 interface, interference, & safety requirements Interface with other subsystems (not an onboard system) Off-board requirements –Power = 2 W (TBR) –Structures Mass = 20 kg (TBR) Volume = 5000 mL (TBR)

Experimental CDIO Capstone Course AC, SYC, SLJ, FP56 Truth Measure Metrology Options Position –External fixed cameras –Onboard cameras –External tracking cameras –Informed tracking cameras with rangefinders –Radar ranging –Reverse IR/Ultrasound Attitude –External fixed cameras –Onboard cameras –Reverse IR/Ultrasound

Experimental CDIO Capstone Course AC, SYC, SLJ, FP57 Truth Measure Metrology Criteria Metrics –Complexity –Cost –Accuracy Constraints –Onboard power –Off-board power –Onboard volume –Off-board volume –Mass –Safety –Interference

Experimental CDIO Capstone Course AC, SYC, SLJ, FP58 Truth Measure Metrology Downselect Note: Power, Volume, Safety, and Interference were considered on a binary scale and are listed as constraints where the subsystem requirements were not met

Experimental CDIO Capstone Course AC, SYC, SLJ, FP59 Metrology Selections Navigation Metrology –IR/Ultrasound for both position and attitude Accurate Inexpensive Meets power, mass, and volume requirements Truth Measure Metrology –External fixed cameras for both position and attitude Could be made real- time Off-board system does not require onboard power, mass, or volume

Experimental CDIO Capstone Course AC, SYC, SLJ, FP60 Metrology Budgets Note: Although separate downselects were performed for attitude and position determination, the same solution emerged for both parts of each metrology subsystem

61 Design Concept Presentation & Conclusion Stephanie Chen Presenter

Experimental CDIO Capstone Course SLC, SEC62 Summary of Concept Propulsion –Compressed Gas Liquid CO 2 or N 2 /Air Structure –Polyhedral truss and shell assembly –Metals and alloys

Experimental CDIO Capstone Course SLC, SEC63 Summary of Concept (cont.) Power –Battery Power Lithium, NiMH Avionics –TATTLETALE processor

Experimental CDIO Capstone Course SLC, SEC64 Summary of Concept (cont.) Communication and Software –RF (Radio Ethernet) –Hierarchy of satellites Metrology –Navigation IR/ultrasound -- measures position and attitude –Truth Measure External fixed cameras

Experimental CDIO Capstone Course SLC, SEC65 Budget per Satellite

Experimental CDIO Capstone Course SLC, SEC66 Preparation for PDR Finalize Design –Set subsystem architecture –Research hardware components –Analyze subsystem integration –Identify and consult experts Prepare Documentation –Compile hardware specs –Validate design

Experimental CDIO Capstone Course SLC, SEC67 Conclusions Subsystems –Preliminary designs investigated –Component research underway Satellite Testbed –Designed to be flown on KC-135 and shuttle middeck –Technology traceable to future satellite missions

Experimental CDIO Capstone Course 68 THE END!