Ece me 491 2 group 4 winter 2009
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ECE/ME 491/2 Group 4 Winter 2009. Benjamin Chen Suhail Gul Wai-Sze Lok Rob Merkle Brian Shaw Renee Soenen. Meet the All-Star Team!. Benjamin Chen Electrical Engineer. Suhail Gul Electrical Engineer. Brian Shaw Computer Engineer. Wai-Sze Lok Mechanical Engineer.

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Ece me 491 2 group 4 winter 2009

ECE/ME 491/2 Group 4Winter 2009

Benjamin Chen

SuhailGul

Wai-SzeLok

Rob Merkle

Brian Shaw

Renee Soenen


Meet the all star team
Meet the All-Star Team!

Benjamin ChenElectrical Engineer

SuhailGulElectrical Engineer

Brian ShawComputer Engineer

Wai-SzeLokMechanical Engineer

Renee Soenen Mechanical Engineer

Rob MerkleMechanical Engineer


Meet joe bot
Meet JOE-BOT!

JOE-BOT IS COMING FOR US!

RAWRR!


DC Motor vs Modified Servo

  • DC Motor:

  • Energy efficient

  • Powerful

  • Modified Servo:

  • Excellent control of speed

  • Sufficient torque and speed in a compact unit

  • Internally geared

  • Don’t need H-bridges


Digital Servo

  • Problem:

  • Kept rotating slowly with no pulse input

  • Possible Reason:

  • Internal mechanical issue

  • Servos and board may not compatible


Dc motor
DC Motor

Problem:

  • Exceeded size

  • Less space

  • Solution:

  • Modified original chassis by machining notches

  • Flip the chassis, so the motors were on the underside


Design changed
Design Changed

  • Machining notches into the sides

  • Flip chassis provide more space

  • 3 platforms instead of 2


Movement

Video of 90° turn

MOVEMENT

Multi – directional wheel called a Transwheel

Two motors drive the set of wheels that are 180° apart

90° degree turns switching power to other set of wheels

Provides versatility of movement with no steering


Movement issues

Video of 45° approach across ramp

MOVEMENT ISSUES

Driving wheels lift off the ground at bottom of ramps

Resolve by driving up the ramp at 45°

New FEA due to different torque on the motor shaft


Finite element analysis

Y

FINITE ELEMENT ANALYSIS

X

N

Ff

15°

10.545°

∑Fx = 0 = Ff-Wx

Free Body Diagram – 3 Dimensional Torque

∑Fy = 0 = N-Wy

∑M = 0 = Ff*r - T

Wx

Wy

Wsin(10.545°)*r=Wx*r=T

W


Fea model
FEA - MODEL

Custom Shaft Assembly

W

T

Nylon Adapter

Motor Shaft

“Universal” Hub


Fire extinguisher
Fire Extinguisher

  • Pump

  • Reservoir

  • Check-valve

  • Nozzle


Fire extinguisher1
Fire Extinguisher

  • Operating at 12 volts

  • 0.54 GPM

  • Mounted at 20 cm

  • Turned on with a relay switch


Fire extinguisher2
Fire Extinguisher

  • VIDEO OF ROBOT EXTINGUISHING FLAME


Cost analysis
Cost Analysis

Material Costs

Labor Costs


Electronic platform selection
Electronic Platform Selection

  • Motorola HCS12 based EVBplusMiniDragon+

    • Easiest to program for (familiarity)

    • Enough I/O connectivity

    • Low enough overall power usage


Stages of development on the design
Stages of development on the design

  • Type of Platform and wheel vs. track

  • Use of servos vs. motors

  • Different types of sensors proposed to be used

  • Navigational Algorithm.


Parts and components
Parts and Components

  • Servo mountings and turrets holder

  • 360⁰ Turret

  • Aluminum base shaping and cutting and supports

  • Mounts for motors.

  • Motor Gears.


Circuits and wiring
Circuits and Wiring

  • H Bridge.

  • Voltage Regulator.


Circuits and wiring1
Circuits and Wiring

  • Pump Switch Circuit.

  • Wiring for Power Sources and sensors


Testing and interfacing the sensors
Testing and Interfacing the Sensors

  • Programming servos and setbacks.

  • Motor Control .

  • Sensors Testing.

    • Digital IR Sensors.

    • Analog IR Sensor.

    • Compass Module.

    • TPA 81.

    • Sonar.


Navigation

  • Basic Movement

  • 4 Omni-Wheels, two wheels each side of the robot.

  • Each wheel can be turned independently of the others.

  • The capability of independent wheel control combined with the placement of the wheels allows for versatile movement controls.

  • Very fast zero-radius turning.

  • Vectored movements, e.g. sideways and 45° diagonal movement.

Navigation


Navigation1
Navigation

Ramps

  • Ramps have posed a formidable challenge for Joe-bot. Due to the wheel placements, it cannot drive straight onto a ramp. This is both a curse and a blessing.

  • It is possible for Joe-bot to detect a ramp simply by checking the long distance rangefinder. If it has detected that it has not moved and the distance is more than a few centimeters, then it is in front of a ramp.

  • The Joe-bot can then turn 45° and travel at that angle to get on the ramp and over it.

    Obstacles

  • Obstacles in the rooms are still a challenge. The sensor array as it stands has a tough time discovering obstacles.


Navigation2
Navigation

Hallway Travel

  • Joe-bot has three pairs of short range IR sensors on the front and sides. Also, it has a long range sonar rangefinder.

  • It can currently navigate the hallway by keeping track of whether or not walls are sensed on either side by the IRs and also using the rangefinder.

    Room Mode

  • When we approach a room, Room Mode becomes active. This is a special procedure for detecting the candle, putting it out and exiting the room we entered.

  • The room is scanned either once or twice; if we detect extra heat (the candle), the second sweep searches for obstacles.

  • We then move toward the candle and extinguish it.



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