Team GPS RoverTeam GPS RoverCritical Design ReviewCritical Design Review

Alex Waskiewicz

Andrew Bousky

Baird McKevitt

Dan Regelson

Zach Hornback

OverviewOverview

Project DescriptionHardware ImplementationSoftware ImplementationMilestonesRisks and Contingencies

PROJECT DESCRIPTIONPROJECT DESCRIPTION

Project GoalsProject Goals The human user will be able to remotely control the rover from a

laptop computer– Direct driving control– Issue location commands

Rover will calculate its current bearing Rover will calculate desired bearing to user specified location Rover will autonomously maneuver to its assigned destination Rover will transmit telemetry to the user Rover will sense and avoid obstacles Rover could have onboard camera(s) providing visual feedback to user. Rover could carry and deploy instrumentation packages

– Examples: Rocket launch platform Environmental sensors Mechanical Manipulator

HARDWARE HARDWARE IMPLEMENTATIONIMPLEMENTATION

VEHICLEVEHICLE

Traxxas Rustler– 445x311x178 mm– 1.69 kg– Top Speed 35 mph– $203 with batteries– High Load Capacity– Replaceable parts

Electronics Platform– Attaches to the chassis– Carries electronics, sensors, and batteries– Interfaces directly with car controls– Weight and Size are constraints

Test: Steering and DrivingTest: Steering and Driving The steering and speed of the vehicle can be controlled

using the PWMs of the microcontroller. Both are controlled by altering the duty cycle of the

input square wave. – The wave (for both steering and speed) has an amplitude of

4.2 Volts and a frequency of 49.75Hz•The duty cycles for steering are:

•Straight – 7.72%•Full Left – 10.21%•Full Right – 5.37%

•The duty cycles for driving are:•Idle – 7.46% •Full Forward – 9.95% •Full Reverse – 4.71 %

Hardware Block DiagramHardware Block Diagram

Microcontroller

DigitalCompass

GPSModule

ProximitySensors

I2CModule

SCIModule

SCIModule

PWMModule

PWMModule

User PC

SteeringMotor

DriveMotor

Test: GPS PartsTest: GPS Parts

Serial communication OOB

Acquired outside signal Impressive spatial

resolution (probably to WAAS enable)

1 Hz update rate – Documentation says

modifiable and/or query-able but currently having technical difficulties

Digital CompassDigital Compass

$60 ½ degree resolution I2C interface Testing will be

imminent once I2C communication on the development board is established

SensorsSensors

Two-forward facing sensors to allow obstacle avoidance

Ultrasonic: 2 x Devantech SRF08 Ranger ($62) 6m range I2C interface

Testing will be imminent once I2C communication on the development board is established

                  

  

Development BoardDevelopment Board

Serial PortsLCDDIP SwitchesLEDsShaft EncoderMini-BreadboardGreat for testing!

Power SubsystemPower Subsystem

3.3V, 5V systemsNeed to pick batteryUse of 2 voltage regulators

– Need to pick type

Will be implemented upon completion of PCB fabrication– Due to development board usefulness

Microcontroller: Freescale Microcontroller: Freescale HCS08HCS08

60K of low-speed Flash4K of internal ram – Requires no external

routingInternal A/DInternal PWM3.3V

Microcontroller: Freescale HCS08 Microcontroller: Freescale HCS08 Memory MapMemory Map

Internal module status/comm registers

Preliminary PCB Layout:Preliminary PCB Layout:

PCB:

•Microcontroller

•RF link

•Voltage Regulators: Power Bus

•Caps/Resistors

4 4 6

US2US1 GPS

Power

V/R

Altium SchematicAltium Schematic

SOFTWARE IMPLEMENTATIONSOFTWARE IMPLEMENTATION

User InterfaceUser Interface

Data Flow DiagramData Flow Diagram

HCS08 Hardware InterfacesHCS08 Hardware Interfaces

Application FunctionsApplication Functions

MILESTONESMILESTONES

Milestone #1 Milestone #1 (Implementation Cycle 1)(Implementation Cycle 1)

User control with Arrow Keys– Serial

Communication (tethered)

– Independent PWM Control

– Windows-based GUI Why?

– Tests many subsystems that are required for GPS Control (i.e. Milestone #2)

Milestone #2 Milestone #2 (Implementation Cycle 2)(Implementation Cycle 2)

GPS Feedback – GPS

communication– Digital

Compass communication (IIC)

– Bearing calculation

Implementation Cycle 3Implementation Cycle 3 Obstacle Avoidance

– Left and Right Sensors with minimal common FOV

– Left and Right allows for an easy avoidance algorithm

Left sensor = high go Right

Right sensor = high go Left

Both = high requires long range detection to avoid

DIVISION OF LABOR AND DIVISION OF LABOR AND RESPONSIBILITIESRESPONSIBILITIES

ALEX ANDREW BAIRD DAN ZACH

•Windows XP GUI

•Development board testing

•Implement control software

•GPS Module

•Schematic & PCB layout

•Chassis Fabrication

•Power Sub-system

•Ultrasonic Sensors

•Digital compass

•Documentation

•Chassis Fabrication

•Schematic and PCB layout

•PWM interface

•Power sub-system

•GPS module

•Implement control software

•Development board testing

SCHEDULESCHEDULE

RISKS AND CONTINGENCY RISKS AND CONTINGENCY PLANPLAN

Updated Risks and ContingencyUpdated Risks and Contingency

Parts availability and shipping times We have purchased many of our discrete

components The car interface is electrically simple• Interfacing I2C components• Microcontroller RAM/Storage limitations• RF Link• Learning curve on design software (CodeWarrior & Altium)• Power Consumption

Questions?Questions?