ECE/ME 491/2 Group 4Winter 2009

Benjamin Chen

Suhail Gul

Wai-Sze Lok

Rob Merkle

Brian Shaw

Renee Soenen

Meet the All-Star Team!

Benjamin ChenElectrical Engineer

Suhail GulElectrical Engineer

Brian ShawComputer Engineer

Wai-Sze LokMechanical Engineer

Rob MerkleMechanical Engineer

Renee Soenen Mechanical Engineer

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

Problem: • Kept rotating slowly with no pulse input

Possible Reason:• Internal mechanical issue• Servos and board may not compatible

Digital Servo

DC MotorProblem: Exceeded size Less space

Solution:• Modified original chassis by machining

notches• Flip the chassis, so the motors were on

the underside

Machining notches into the sides

Flip chassis provide more space

3 platforms instead of 2

Design Changed

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

Video of 90° turn

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

Video of 45° approach across ramp

FINITE ELEMENT ANALYSIS

Free Body Diagram – 3 Dimensional Torque

N

Ff

Wy

W

Wx

YX

15

°

10.545° ∑Fx = 0 = Ff-Wx

∑Fy = 0 = N-Wy

∑M = 0 = Ff*r - T

Wsin(10.545°)*r=Wx*r=T

FEA - MODELCustom Shaft Assembly

WT

Motor Shaft

“Universal” Hub

Nylon Adapter

Fire Extinguisher

Pump Reservoir Check-valve Nozzle

Fire Extinguisher Operating at 12 volts 0.54 GPM Mounted at 20 cm Turned on with a relay switch

Fire Extinguisher VIDEO OF ROBOT EXTINGUISHING FLAME

Cost Analysis

Item Price Quantity CostSharp GP2D120 IR Range Sensor - 4 to 30 cm $13.99 2 $27.98Devantech Ultrasonic Range Finder SRF08 $64.99 1 $64.99Sharp GP2Y0D810F Digital Distance Sensor 10 cm $6.38 6 $38.28360 Degree Pan Turret (Turret and Servo) $29.95 1 $29.95Silicone aquarium tubing $4.23 1 $4.23Trico Chevrolet C1500 Washer Pump $17.45 1 $17.45Check-valve for aquarium $1.99 1 $1.99Durbo S12 Square Fuel Tank 12 oz. $4.99 1 $4.991/4 inch ID silicone airline tubing sold by the foot $1.99 0.5 $1.001/4 GGA-10 FullJet Brass Nozzle $26.66 1 $26.664 in. Omniwheels $11.11 4 $44.441/4" alum. Hub for sumo tires (pair) $8.00 2 $16.00ML-50 50:1 Geared Motor $26.95 4 $107.80Devantech TPA81 Thermal Array Sensors $110.99 1 $110.99Rectangular NiCd 12V 5000mAh Battery Pack $54.23 1 $54.23Total $550.98

Processes Time (hour) labor cost per hour Costtesting (hardware and software) 6 $15.00 $90.00assembly 4 $10.00 $40.00Total $130.00

Material Costs

Labor Costs

Electronic Platform Selection

Motorola HCS12 based EVBplus MiniDragon+ Easiest to program for (familiarity) Enough I/O connectivity Low enough overall power usage

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

Servo mountings and turrets holder 360 Turret⁰

Aluminum base shaping and cutting and supports

Mounts for motors.

Motor Gears.

Circuits and Wiring

H Bridge.

Voltage Regulator.

Circuits and Wiring

Pump Switch Circuit.

Wiring for Power Sources and 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.

NavigationBasic 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

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.

NavigationHallway 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.

Any questions?