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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
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
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.
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.