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ECE 477 Design Review Team 16  Spring 2014

The Home Utility Robot. ECE 477 Design Review Team 16  Spring 2014. Roshan Parikh. Jordan Glassley. Michael Hayashi. Sage Hill. Outline. Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation

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ECE 477 Design Review Team 16  Spring 2014

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  1. The Home Utility Robot ECE 477 Design Review Team 16  Spring 2014 RoshanParikh JordanGlassley MichaelHayashi SageHill

  2. Outline • Project overview • Project-specific success criteria • Block diagram • Component selection rationale • Packaging design • Schematic and theory of operation • PCB layout • Software design/development status • Project completion timeline • Questions / discussion

  3. Project Overview • Semi-autonomous robot with: • iRobot Create base • Chores on a schedule (I.E. Sweeping) • Manual drive capabilities • Automatic “Beverage-grabbing” mode once manually driven to mini-refrigerator

  4. Project-Specific Success Criteria • An ability to control the drive motors to move the robot around • An ability to remotely control the robot via RF • An ability to detect obstacles using ultrasonic sensors and avoid them • An ability to mechanically move the robot’s drink-manipulating arm and pick up an object • An ability to perform tasks (such as sweeping the room) according to a user generated schedule

  5. Block Diagram

  6. Block Diagram

  7. Component Selection Rationale • STMicroelectronics L6205 • Pros: • Low drain-source resistance when MOSFETs on (0.3Ω) • Overcurrent protection • Dual full-bridge mode or paralleled mode for single motor • 3 I/O signals (optionalPWM) • Cons: • Flyback diodes are internal • No speed control

  8. Component Selection Rationale • TI LM2675 Buck Converter • Pros: • Available in SOIC package • 12V, 5V, and 3.3V fixed output versions reduce external parts • 1A output for driving motors • Extensive documentation • No heatsink required • Cons: • Expensive, high-quality passives • Fast switching generates EMI

  9. Component Selection Rationale • Microchip PIC24EP512MC206 • Best match of peripherals • High speed motor control • Reprogrammable peripherals for ease of placement • Low typical current (0.6 mA/MHz -> 24 mA @ 40 MHz)

  10. Component Selection Rationale • Microchip RF Transceiver • Pros: • Operates with a 3.3V supply • Built in antenna • Built in packet filtering • Small Size • Cons: • QFN package type • Special placement on PCB required

  11. Component Selection Rationale • Parallax RFID Reader • Pros: • Easy to mount on robotic arm • Reads passive RFID tags • Cons: • Operates on a 5V supply

  12. Component Selection Rationale • Raspberry Pi • Easy WiFi and camera configuration • Onboard communication interfaces: SPI, UART, I2C • Android Device • 50.3% market share as of Nov 2013 • Source: http://news.cnet.com/8301-13579_3-57616679-37/iphone-market-share-shrinks-as-android-windows-phone-grow/ • Low cost development • Portability

  13. Component Selection Rationale • LV-EZ2 Sonar Range Finder • Pros: • Operates on 3.3V supply with little error in range data • Low typical current (2mA) • Provides range information at 1 inch resolution • Cons: • Shortest ranging distance is 6 inches

  14. Packaging Design

  15. Packaging Design

  16. Packaging Design

  17. Packaging Design

  18. Schematic/Theory of Operation • Six Basic Blocks for PCB on iRobot Create • Power Block • Microcontroller Block • Sensor Block • Wireless Communications Block • Display Block • Motor Driver Block

  19. Schematic/Theory of Operation • 3x LM2675 SMPS • Each uses 2 conformal coated tantalum capacitors • Shielded ferrite core inductors for size/EMI balance • High-voltage Schottky barrier diode

  20. Schematic/Theory of Operation • PIC24EP512MC206 breaks out all pins • 8.00 MHz crystal drives up to 32pF • Programmable using Microchip MPLAB • 2-pin header bridged to enter debug mode

  21. Schematic/Theory of Operation • Ribbon cables with IDC’s will connect sensors to headers • RFID reader needs 5V signals (level translated) • Ultrasonic Sensor gives analog output

  22. Schematic/Theory of Operation • Raspberry Pi cable secured in 3.5mm audio jack carrying I2C signals • RF transceiver mounted on board with its own bulk capacitor • RF module communicates using SPI and two interrupts • Raspberry Pi requires level translation to 5V

  23. Schematic/Theory of Operation • SPI used to send data to 8-bit serial in, parallel out (SIPO) buffered shift register • LCD uses HD44780 driver to decode status messages about the robot’s state

  24. Schematic/Theory of Operation • One L6205 IC is used to drive the arm motors independently while another L6205 IC controls the conveyor belt motor • Full H-bridge driving used in all cases • Software controls direction and effective duty cycle for the 12-V motors • 2-pin locking Molex connectors to motors • D-sub 25-pin receptacle to communicate, receive power, and turn on iRobot Create • Level translator for signals to iRobot Create

  25. Schematic/Theory of Operation • Fridge Board is used to drive a separate DC motor to open the mini-refrigerator door when RF signal received from robot • Same L6205 IC and RF transceiver • 9S12 series microcontroller used with level translation to RF transceiver • Programmable using SCI over D-sub 9 • 1.25-A LDO linear regulators supply 5V and 3.3V • Barrel plug receives regulated 12V

  26. PCB Layout

  27. Software Design/Development Status • Command driven modes of operation • Interrupt system to respond to user request or detected obstacle

  28. Software Design/Development Status Android Application/Robot Communication Scheme

  29. Software Design/Development Status • Prototyped SPI communication to LCD display • Prototyped UART communication with RFID reader • Prototyped reading A/D ultrasonic sensor • Initial development of Android application • Video stream from Raspberry Pi viewable in web browser

  30. Project Completion Timeline • Week of: (Mondays listed) • March 10th • PCB finished • Power circuitry prototyped • March 17th • Spring Break • March 24th • Packaging parts ordering, assembly begun • PCB assembled • Algorithms finalized, implementation started

  31. Project Completion Timeline • Week of: (Mondays listed) • March 31st • Packaging assembly • Code stresstesting • April 7th • Documentation • April 14th • Final packaging testing & debug • April 21st • Last minute testing & debug issues • April 28th (DEAD WEEK) • End of project deliverables

  32. Questions / Discussion

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