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Critical Design Review February 2, 2011

Filip Maksimovic Viliam Klein Peter Zhang Corrina Gibson Brandon Benjamin Vicki Hsu Elliott Richerson Tyson Wolach John Jakes Aerospace Advisor: Scott Palo. Critical Design Review February 2, 2011. Introduction. JPL funded project with the Aerospace department

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Critical Design Review February 2, 2011

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  1. Filip Maksimovic Viliam Klein Peter Zhang Corrina Gibson Brandon Benjamin Vicki Hsu Elliott Richerson Tyson Wolach John Jakes Aerospace Advisor: Scott Palo Critical Design Review February 2, 2011 XROVER CDR

  2. Introduction • JPL funded project with the Aerospace department • Goals are to explore feasibility of using multi-rover configurations for extraterrestrial exploration • Our system architecture has one mother rover and two deployable child rovers • Continuation of a project started two years ago

  3. Objectives

  4. Concept of Operations Ground Station (GS) Location of Interest (LOI) Identified Relay Ability Confirmed Rover Mission Sent to MR MR to deployment location Mother Rover (MR) CR Status and Data Evaluated Relay CR Commands Sent to CRs dock &undock Relay Area Terrain Location of Interest Ground Station Mother Rover Child Rovers C&DH

  5. Concept of Operations Ground Station (GS) Location of Interest (LOI) Identified Relay Ability Confirmed Rover Mission Sent to MR Relay Waypoint C&DH Relay CR and MR Communication Mother Rover (MR) CR Status and Data Evaluated Relay CR Commands Sent to CRs dock &undock Relay Area Terrain Location of Interest Ground Station Mother Rover Child Rovers C&DH

  6. Concept of Operations Ground Station (GS) Location of Interest (LOI) Identified Relay Ability Confirmed Rover Mission Sent to MR Relay Waypoint C&DH Relay CR and MR Communication Mother Rover (MR) CR Status and Data Evaluated Relay CR Commands Sent to CRs dock &undock Mission CR Relay Area Terrain Location of Interest Ground Station Mother Rover Child Rovers C&DH

  7. Concept of Operations LOI Terrain boundary of communication Ground Station (GS) Location of Interest (LOI) Identified C&DH Image Obtained by Mission CR Relay Ability Confirmed Mission CR Position Evaluated Rover Mission Sent to MR isolatedtravel Mission CR and Relay CR Comm. Relay Waypoint Relay CR and MR Communication Mother Rover (MR) CR Status and Data Evaluated Relay CR Commands Sent to CRs dock &undock Mission CR Relay Area Terrain Location of Interest Ground Station Mother Rover Child Rovers C&DH

  8. Electronics Functional Block Diagram Ground Station Mother Rover Power Power GUI Computer Wireless Router USB User Input CDH MR Drive RS232 Wireless Network User inputs ‘waypoints’ to control child rovers Wireless Router Child Rover Child Rover Wireless Router Wireless Router Desired Location Desired Location CDH Power CDH Power Motor Control, Interrupt Position Motor Control, Interrupt Position Navigation CR Drive Navigation CR Drive

  9. Child Rover Functional Block Diagram Child Rover Wireless Router 5V Power Desired Location Data CDH Power 5V 5V/12V Navigation Data Interrupt, Request Data Sensors CR Drive RS232 Motor Drive

  10. Child Rover Drive Subsystem Functional Decomposition

  11. Child Rover Drive Subsystem Block Diagram RS232 5V/12V Motor voltages

  12. Child Rover Drive Subsystem Further Functional Decomposition

  13. Sensors Functional Decomposition

  14. Further Sensor Functional Decomposition

  15. Quadrature • Quadrature encoders have an A line and a B line 90o out of phase • Phase lead/lag is used to determine whether shaft is rotating clockwise or counter-clockwise • Frequency of signals can be used to determine rotation rate • If encoder spins too quickly, sometimes counter will miss a count resulting in erroneous reading • Index line signals whenever one revolution has completed and can be used to “zero out” the encoder count to remedy the missed-counts problem

  16. Rangefinding Crickets

  17. Power System Functional Decomposition

  18. Power System Block Diagram 5V 14.4V Li-ion Pico PSU Motor Controllers Onboard Optoisolator 12V Gumstix 5V Crickets, Webcam 5V Electronic Isolation 6V AAA Linear Regulator I/O Expander 5V Sensors 5V

  19. CDH Functional Decomposition

  20. CDH Block Diagram Crickets Range Interrupt CR Position, Image Image Camera Gumstix Computer Mesh Router Request Picture Requested Position, Mission Info Interrupt, Motor Command Sensor Data USB I/O Expander SPI Bus IMU Data Encoder Data

  21. I/O Expander Schematic (rev.1)

  22. I/O Expander Block Diagram Aux PSU Encoder Counter 5V Regulator Encoder Counter Encoder Counter SPI RS232 IMU Atmega128 USB To Gumstix RS232 Motor Control Encoder Counter Encoder Counter Encoder Counter

  23. I/O Expander PCB Layout • Revision 2 plans: • Fix reset pin circuit • Add VCC, GND pins for all encoder and motor headers • Wire the USB properly • Change LED circuit so that they are off when line is high • Move USB and IMU connectors to same side of board

  24. SPI Timing Diagram • Both encoders and IMU have continuous data modes where they will release data while the SS line is held low • Each encoder has 4 bytes of data, and the IMU can provide 39 bytes of status registers and data

  25. Additional IMU Timing Information • Maximum SPI clock is 1MHz • Minimum stall time is 9 clock cycles (9 µs) • 600 µs delay between sync timer and data ready when specific data is requested

  26. Encoder Counter Circuit ATMega128 Free/Powered Wheel Encoder SPI Protocol Encoder to Counter Converter LS366R 32bit Counter Each component is powered by regulated 5V from the AUX battery Aux Battery

  27. PID Control Simulation • PID simulation run in Mathematica to determine effectiveness of controller in following waypoints • Input to simulation is actual CR position

  28. GUI

  29. Software – Finite State Machine Logic Docked mission started yes Conn? no Wait Rotate to Next Waypoint no Conn? Safe returning = true yes yes yes no no Returning? Returning? Undock waypoint? no Reverse Waypoints Calibrate yes Imaging Switch COMM Interface File Update Rotate to LOI DEFCON1 no Final waypoint Relay rover? Returning? yes no yes Mission Complete no yes Wait for Mission CR Drive Waypoint Reached Rotate to Next Waypoint

  30. Software – How to determine position x’’, y’’, z’’ The Black Box θ‘, ψ’, φ’ x, y, z, θ, ψ, φ r (crickets) V, r (encoders)

  31. Wireless Communication • Must provide communication between GS, MR, and CRs • Also must provide relay communication to a hidden CR • Solution is an ad-hoc mesh network to maximize throughput and minimize packet loss • These from Alfa Corporation are wireless mesh routers • They also come with nice software showing packet transfer and were free

  32. Budget

  33. Manufacturing Schedule Milestone 1 Milestone 2

  34. Verification and Testing Schedule Milestone 1 Milestone 2

  35. Milestone Goals

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