1 QB50 CubeSat PDR Team: STAR Satellite Testb tbed for r Attitude Response Matt Hong, Nick Andrews, Dylan Cooper, Colin Peterson, Nathan Eckert, Sasanka Bathula, Cole Glommen
2 Presentation Outline Mission Introduction Project Description Feasibility – Interface Board Feasibility – Sun Sensor Table Feasibility – Helmholtz Cage Test Status Summary Backup Slides
3 Mission Introduction Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test
4 QB50 Satellite – Attitude Determination and Control System (ADCS) • One of 50 CubeSats • 400 km orbit • ~ 8 month mission • Provide in situ thermosphere measurements
5 Project Description Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test
6 ADCS Verification ConOps 1. Interface Board 1. USB from simulation to interface board 2. Connect interface to ADCS 3. Run Simulation Matlab Simulation Interface Board Customer ADCS 2. Sun Sensor Calibration Table 3. Helmholtz Hanging Apparatus 2 Angle of Table 1. Integrate CubeSat 2. Rotate Table to desired angle 1. Integrate CubeSat 3. Compare angle of table to 2. Fire Magnetorquer angle reported by satellite 3. Satellite rotates to verify functionality
7 Interface Board – Baseline Design Interface Board – Block Diagram Functional Requirements • The simulation shall be Baseline Design modified to communicate with interface board • The interface board shall Baseline design decision is transmit simulated sensor data to use PIC microcontrollers to the ADCS board to emulate the sensors and • The interface board shall acquire data sample magnetorquer Pulse Width Modulation (PWM) signals • The interface board shall measure power draw of ADCS board
8 ADCS Verification ConOps 1. Interface Board 1. USB from simulation to interface board 2. Connect interface to ADCS 3. Run Simulation Matlab Simulation Interface Board Customer ADCS 2. Sun Sensor Calibration Table 3. Helmholtz Hanging Apparatus 2 Angle of Table 1. Integrate CubeSat 2. Rotate Table to desired angle 1. Integrate CubeSat 3. Compare angle of table to 2. Fire Magnetorquer angle reported by satellite 3. Satellite rotates to verify functionality
9 Sun Sensor Calibration Table – Baseline Design Functional Requirements Baseline Design • The turn table shall be turned to desired angle Baseline design decision is to manually rotate turn table • The turn table shall have a and use a magnetic encoder resolution of 1° with ±0.5° to display position on an LCD accuracy display
10 ADCS Verification ConOps 1. Interface Board 1. USB from simulation to interface board 2. Connect interface to ADCS 3. Run Simulation Matlab Simulation Interface Board Customer ADCS 2. Sun Sensor Calibration Table 3. Helmholtz Hanging Apparatus 2 Angle of Table 1. Integrate CubeSat 2. Rotate Table to desired angle 1. Integrate CubeSat 3. Compare angle of table to 2. Fire Magnetorquer angle reported by satellite 3. Satellite rotates to verify functionality
11 Helmholtz Cage – Baseline Design Functional Requirements Baseline Design • The CubeSat shall be suspended in the HelmHoltz Cage Baseline design decision is to hang the CubeSat with a line • The CubeSat shall rotate with 1 degree of freedom(DoF)
12 Baseline Feasibility Interface Board Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test
13 Interface Board - Feasibility • Rate Gyro • Magnetometer GPS (USART*) Matlab Simulation Interface Board Customer ADCS Magnetorquers Sun Sensors (I 2 C*) *I 2 C = Inter-Integrated Communication *USART = Universal Synchronous Asynchronous Receiver/Transmitter
14 Simulation to Interface Board - *UART = Universal Synchronous Receiver/Transmitter *USB = Universal Serial Bus Feasibility USB UART Matlab Simulation FTDI USB* to UART* Interface Board • Compatible with Matlab using included Customer ADCS drivers from FTDI • Converts USB into a common communication protocol used by microcontrollers
Interface Board to ADCS - Feasibility 15 I 2 C Bus • Allows multiple devices to communicate with each other Interface Board Slave Microcontroller • Designated master device with slave devices • Slave devices are assigned one address Magnetorquer PWM CCP* Master Microcontroller Analog Input Slave Microcontroller UART USB UART Digital Analog Voltage I 2 C Power Customer ADCS *CCP = Capture/Compare/PWM
16 Baseline Feasibility Sun Sensor Calibration Table Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test
17 Sun Sensor Calibration Table - Feasibility Side: Angled: Back: Diameter = 50 cm Supports 1U, 2U, and 3U CubeSats in all Height = 4 cm orientations
18 Sun Sensor Calibration Table - Usage Rotation types: 1) Manual – rotate to desired angle 2) Motor – to be implemented by customer 0˚ Light Source Rotation 0˚ 45˚
19 Sun Sensor Calibration Table - Feasibility 1. Rotate with resolution of 1˚ with ± 0.5˚ accuracy • 10 bit rotary encoder • Resolution = 360˚/2 10 = 0.352˚ per bit < 1˚ • Angle etchings • Physical – electronics redundancy • Arc length spacing = circumference/360˚ = 0.172”/degree • Board diameter = 50 cm = 19.685” Magnetic encoder Angle etchings All measurements in centimeters
20 Sun Sensor Calibration Table - Feasibility 2. Display angular position to user • LCD display output 3. Manually operated with potential to be automated • 10 Hz Sun sensor, RPM of< 5/3 • Torque required = 0.0746 N*m Ball bearing Gears DC motor LCD display Angle = 42.0586 ˚
21 Baseline Feasibility Helmholtz Cage Test Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test
Helmholtz Cage Structure Feasibility TEST: • The QB50 will sense attitude and make necessary adjustments using its magnetorquers Requirements • Allow for rotation ± 360° about one axis • Torquing authority of 0.1 Am 2 equivalent to 5 E -6 Nm • Less than 5 E-6 Nm resistance to rotation • Do not interfere with the Satellite’s magnetometer readings 61 cm 22
Helmholtz Cage Structure Feasibility Satellite Orientations Z Y X Z Y X 23
Helmholtz Cage Testing Structure Feasibility M D = ρ*α 2 *t 2 *h*L 4 *C D / (64) • Assume C D = 2.05 • Assume Moment of Inertia of a hollow rectangular prism τ Line = 0.5*π* r 4 *G*θ*L -1 • Assume line can be modeled as a Rod τ Sat = μ x B ⇒ τ Sat > τ Line + M D 24
Helmholtz Cage Testing Structure – Feasibility Line Resistive Torque τ Line = I * α τ Line = Resistive Torque from the line τ Line I = mass moment of inertia of the rod I = m * (2 * r 2 + h 2 ) / 12 α = angular acceleration of the rod r = cross-sectional radius of the line θ = angular deflection = 360 ° α = 2 * θ * t -2 360° t = time for the rod to rotate θ ° • found experimentally τ Line = 3.5835E -6 Nm Displace Rod 360° measure time (t) until rod returns to inital 25
26 Status Summary Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test
27 Budget Feasibility Preliminary Budget Interface Board • Funding: • $5,000.00 CU ASEN Sun Sensor Turn 12% Table • Total Project Cost: 13% Hanging in • ~$2,000 Helmholtz • 5 revisions for electronics 59% 10% Extra Proj. Elem. • Project Margin: 6% • ~$3,000 Margin *certain project elements costs are estimates/TBD
28 Project Schedule
29 Future Studies • Interface Board • Design layout of interface board • Selection of precise PIC microcontrollers • Sun Sensor Calibration Table • Design encoder-LCD circuit • Selection of gears and gear ratio • Helmholtz Cage Test • Further testing of hanging lines for margin • Software • Increase of simulation accuracy
30 Questions? Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test
31 Backup Slides • Interface Board • Simulation • Sun Sensor Calibration Table • Helmholtz Cage Test • Logistics Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test Backup Slides
32 Interface Board Feasibility – Feasibility – Feasibility – Mission Project Status Backup Interface Sun Sensor Helmholtz Introduction Description Summary Slides Board Table Cage Test Backup Slides
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