Design Review: RoboSiM Robotic Surveillance in Motion Bryan McDonnel Michael Mize Ryan Taylor Miles Whittaker

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

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

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.

Block Diagram

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

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

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

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

Packaging Design Top View

Packaging Design

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

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

Block Diagram

Microcontroller

Microcontroller Reset PICKIT-2

Microcontroller Audio

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

Power

Motor Control

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

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

Audio

PCB Layout: Overview Low-Power High-Power

PCB Layout: Power Supply 3.3V Supply 7.2V Supply

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

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

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

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

PCB Layout: Motor Control H-Bridge Controllers

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

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

PCB Layout: Motor Control Planned Thermal Relief Plane

PCB Layout: Microcontroller PIC24H Microcontroller

PCB Layout: Microcontroller four decoupling caps placed close to pins

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

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

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

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

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

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

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

Software Design r = Radius of Earth

Software Design

Completion Timeline Week Date Task Notes 9 12-Mar Final Schematic/Layout 10 19-Mar Software Development Spring Break 11 26-Mar PCB Assembly 12 2-Apr PCB Assembly Complete External Software Complete 13 9-Apr Software Complete, Debug Embedded Software Complete 14 16-Apr Field Testing 15 23-Apr 16 30-Apr Testing Complete, Demonstration

Questions?