bryan mcdonnel michael mize ryan taylor miles whittaker

Design Review: RoboSiMRobotic Surveillance in Motion

Bryan McDonnelMichael MizeRyan TaylorMiles 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▪ 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 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

1. Obtain data from SD card and note current location

2. Validate SD card coordinates and initialize systems

3. Start motors and travel to destination while continuously sampling sensors

Navigate around objects using compass and sensors

4. At destination, sample microphone using ADC

5. 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

MicrocontrollerReset

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

7.2V Supply

3.3V Supply

PCB Layout: Power Supply

75mil traces

High Current(up to 5.1A)

Routed to shorten current loops

(both regulators)

1

3

2 4 5

PCB Layout: Power Supply

Routed to shorten current loops

(both regulators)

1 32

4 5

PCB Layout: Power Supply

Redundant caps

to prevent brownout

during motor load

changes

Additional caps

PCB Layout: Power Supply

H-Bridge Controllers

PCB Layout: Motor Control

H-Bridge Controllers

75mil traces

High Current(up to 5.1A)

PCB Layout: Motor Control

Data & Power Traces

Separated

Data

Power

PCB Layout: Motor Control

Planned ThermalRelief Plane

PCB Layout: Motor Control

PIC24H Microcontroller

PCB Layout: Microcontroller

PCB Layout: Microcontroller

four decoupling capsplaced 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

Mic & Audio Amplifier

Ultrasonic SensorInputs

Reset Circuit

SD Card & LCD Headers

GPS, Digital Compass, & PICKIT Headers

AnalogDigital

PCB Layout: Peripherals

Separation of

analog & digital

interfaces

AnalogDigital

PCB Layout: Peripherals

Analog and switching lines cross

at right

angles (2 cases)

AnalogDigital

PCB Layout: Peripherals

Peripherals connected

through headers to preserve

board area & minimize

traces(9 headers)

AnalogDigital

Software Design

Navigation Haversine Formula▪ Used to calculate great-circle distances

Only need three points▪ Robot position:▪ Target position:▪ North pole:

( , )r rR ( , )t tT ( , )n nN

Software Design

2 2sin sin sin sin2 2

r th

2 arcsinc r h

n r n t r t

r = Radius of Earth

Software Design

t r t r

m

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 Field Testing

16 30-AprTesting Complete, Demonstration

Questions?