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Design Review: RoboSiM Robotic Surveillance in Motion

Bryan McDonnel Michael Mize Ryan Taylor Miles Whittaker. Design Review: RoboSiM Robotic Surveillance in Motion. Outline. Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation PCB layout

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Design Review: RoboSiM Robotic Surveillance in Motion

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  1. Bryan McDonnel Michael Mize Ryan Taylor Miles Whittaker Design Review: RoboSiMRobotic Surveillance in Motion

  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. RoboSiM Overview • Robotic surveillance vehicle • Navigate to a target • Avoid obstacles • Survey target location by recording audio

  4. Project Specific Success Criteria Demonstrate an ability to: • Display the current status of the robot on an external display. • Read from and write to a portable media device. • Make navigational decisions based on sensor, GPS, and digital compass data. • Control the robot using steering and motor drive. • Capture and encode audio.

  5. Block Diagram

  6. Component Selection • Microcontroller: PIC24H • Audio encoding • G.711 needs 1 MIPS • Capable of 40 MIPS • Free libraries from Microchip • Numerous peripherals • 2 SPIs, 2 I2Cs, 2 UARTs • Robust IDE • MPLAB and development board

  7. Component Selection • GPS Module: Skytraq VENUS • Accurate • < 2.5m CEP • Configurable update rate • Up to 10 Hz • Form factor • Breakout board • SMA connector

  8. Component Selection • Sensors: Ultrasonic • Range • 6” – 254” with 1” resolution: (Vcc/256)/in • Wide beam for general obstacle detection • Multiple interface types • Digital serial • Analog voltage • PWM

  9. Packaging Design • RP5 Chassis • Tank treads • Small • Motors • 6” per second nominal • Forward-mounted microphone • Forward and side-mounted ultrasonic sensors

  10. Packaging Design Top View

  11. Packaging Design

  12. Theory of Operation • Obtain data from SD card and note current location • Validate SD card coordinates and initialize systems • Start motors and travel to destination while continuously sampling sensors • Navigate around objects using compass and sensors • At destination, sample microphone using ADC • Return to starting location

  13. Theory of Operation/Schematics • Five Key Functional Blocks • Object Detection • Navigation • Motor Control & Power • Audio Capture • Display and Storage

  14. Block Diagram

  15. Microcontroller

  16. Microcontroller Reset PICKIT-2

  17. Microcontroller Audio

  18. Power - Battery • Regulators designed to accept 8 – 11 V input • 8.4V NiMH AA rechargeable battery pack used as input • 2200 mAh • Buck regulators used to produce 7.2V and 3.3V output • Motors draw 2.45 A each at stall

  19. Power

  20. Motor Control

  21. Navigation • Digital compass and GPS used • GPS runs at 10 Hz, Digital compass at 20 Hz • Dead reckoning between GPS samples • GPS sends NMEA* string over UART that will be parsed to determine current location • Algorithm described in software narrative *National Marine Electronics Association 0183 Standard

  22. Object Detection • Three ultrasonic sensors attached to chassis • Front-, left-, and right-facing • Sensors run in continuous scan mode at 20 Hz • Distance to object corresponds to 6.45 mV / in [(Vcc/512)/in] • Sensors sampled by ADC using 12-bit resolution

  23. Audio

  24. PCB Layout: Overview Low-Power High-Power

  25. PCB Layout: Power Supply 3.3V Supply 7.2V Supply

  26. PCB Layout: Power Supply High Current (up to 5.1A) 75mil traces

  27. PCB Layout: Power Supply Routed to shorten current loops (both regulators) 2 4 5 1 3

  28. PCB Layout: Power Supply Routed to shorten current loops (both regulators) 4 5 1 2 3

  29. PCB Layout: Power Supply Additional caps Redundant caps to prevent brownout during motor load changes

  30. PCB Layout: Motor Control H-Bridge Controllers

  31. PCB Layout: Motor Control H-Bridge Controllers High Current (up to 5.1A) 75mil traces

  32. PCB Layout: Motor Control Data Data & Power Traces Separated Power

  33. PCB Layout: Motor Control Planned Thermal Relief Plane

  34. PCB Layout: Microcontroller PIC24H Microcontroller

  35. PCB Layout: Microcontroller four decoupling caps placed close to pins

  36. PCB Layout: Microcontroller Two caps under board to better utilize space

  37. PCB Layout: Microcontroller Unconnected pins configured as outputs and left floating

  38. PCB Layout: Peripherals Analog Digital SD Card & LCD Headers Mic & Audio Amplifier Ultrasonic Sensor Inputs GPS, Digital Compass, & PICKIT Headers Reset Circuit

  39. PCB Layout: Peripherals Analog Digital Separation of analog & digital interfaces

  40. PCB Layout: Peripherals Analog Digital Analog and switching lines cross at right angles (2 cases)

  41. PCB Layout: Peripherals Analog Digital Peripherals connected through headers to preserve board area & minimize traces (9 headers)

  42. Software Design • Navigation • Haversine Formula • Used to calculate great-circle distances • Only need three points • Robot position: • Target position: • North pole:

  43. Software Design r = Radius of Earth

  44. Software Design

  45. Completion Timeline

  46. Questions?

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