ECE/ME 491/2 Group 4Winter 2009

Benjamin ChenSuhail Gul

Wai-Sze LokRob MerkleBrian Shaw

Renee Soenen

Objective: To build an autonomous firefighting robot

Structural Design Considerations Small or 0° turn radiusGiven size restriction and ground

clearanceFrictionType of drive-trainWeight and center of gravity location

Wheels First considered to determine range of

chassis size to work withQuantity and type which help with finalizing

drive-trainExplored track style, multi-directional and

standard hobbyist rubber wheelsSize to provide enough ground clearance

Chassis and Drive-trainShapes and sizes

Square, triangular and rectangularMaterial

Lightweight and easy to machineDeck quantityQuantity, speed and torque of motorsSteering mechanism

Chassis and Drive-trainCurrent DesignChose optimal shape for best wheel

configuration for designAluminum chassisTwo decks Four modified servos to drive

Possible Structural IssuesAmount of stress on shaft of servos

Possibly perform FEA to determine max stressClearance with face of wheels

Change wheels (last resort)Vibration

Change thickness or material of chassis for more flexibility

Shock absorption on wheel (last resort)

Rendered output of robot

DC Motor vs Modified ServoDC Motor: Energy efficient Powerful

Modified Servo: Excellent control of speed Sufficient torque and speed in a compact

unit Internally geared

Parameter on picking servoWeight of the robotDesired terrainDesired velocity and accelerationVoltagePower consumptioncontrollability

Robot Motor Factor (RMF)rpstorqueRMF

2velocityonacceleratiweightRMF

Fire Extinguishing MechanismDidn’t want to use airSeveral different ideasCO2

System similar to a paintball gunPaintball gun worked, but not feasible

Foam SpraySmall travel shaving cream canOnly shot a stream about 3 in.

Fire Extinguishing MechanismSpray Bottle

Febreeze bottle, other press down bottlePump-spray system (current)

Windshield washer nozzles

Fire Extinguishing MechanismFuture work

Testing for volumetric flow rate and operating pressure

Buying misting nozzlesTesting

Range, operation time, etc.

Constraints for electronic platformSizePower requirementProcessing abilityI/O optionsProgrammability

Possible platform optionsMotorola HCS12 based EVBplus

MiniDragon+ or MiniDragon-Plus2 microcontroller

Xilinx Spartan3 based development boardTexas Instruments OMAP based Gumstix

Overo or Marvell PXA270 based Gumstix Verdex Pro

ADI Blackfin based microcontrollerIntel Atom based D945GCLF development

board

Remaining Work• Working on basic design requirements.

• Custom building parts required for the base.

• Working on basic design.

• Connecting the sensors and servos.

• Working on circuits and power requirement.

PROGRAMMINGWorking on programming servos

Working on programming microcontroller for connecting sensors.

Working on pathfinding algorithms

NavigationFirst ideas for navigation:• Strictly sensor-based travel.

• Specific behavior algorithms, such as straight-line and always-left-turn kind of algorithms.

• Knowledge of the house layout via a stored map.

NavigationThe robots primary method of understanding the

environment will be vision via a camera.

The camera-based vision system is complemented by an array of sensors for redundancy and verification purposes.

Implementing a vision-based system is more technically challenging than the previous ideas, but the benefits of vision are many.

Original project timelineA tad too optimistic…

Any Questions?We won’t tell you too many details of our

proprietary implementation…