ECE 485: Electrical Engineering Design I Project

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ECE 485 Electrical Engineering Design I Project

• By Group 2 Joel Marcia,
• Paul Rosensteel,
• Scott Laminack,
• and Justin Lanham

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Overview The Problem

• To design and implement the hardware and software
  to control the Trekker Robot in three
  competitions
• Go around outside loop 3 times.
• Go around outside loop at least once, then take
  the inside loop twice.
• Evade an obstacle on the track and follow the
  guidelines from competition 2.

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Overview Specifications

• OOPic R with a L7806 6V Voltage Regulator
  (TO220 Package)
• OOPic R Expansion Board

Pictures from http//www.superdroidrobots.com/shop
/category.asp?catid25
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Overview Specifications

• A Sharp GP2D12 IR Sensor
• A Devantech SRF04 Ultrasonic Ranger

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Overview Specifications

• 4 QRB1134 Phototransistors with mounting bracket
• 2 HiTec HS-422 servos to control the wheels
• 1 HiTec HS-311 servo to control the ranger or IR
  sensor

Pictures from http//www.superdroidrobots.com/shop
/category.asp?catid25
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Optimizing Software andAlgorithms
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Game Plan

• No If Then statements
• Might be easier getting stated, but more work in
  the long run
• Use object codes to create a virtual circuit
• Simplify the code
• Easier to debug
• Changes are easier to make

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Key Object Codes Used

• oServoSP1
• oTracker

• oNavCon
• oCompare2

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oServoSP1

• Designed to control servos or to interface servos
  with different objects
• Specifically used with hacked servos
• Supports URCP values (positive and negative
  values)
• Unique property set Value property to 0, no
  pulses are sent to the servo (wheels stop
  completely)

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Key Points using oServoSP1

• Set the left servo InvertOut property to 1
  sets wheels turning in the same direction
• Set Refresh property to 1 doubles the pulses
  sent to servos (increases torque)
• Tested using oscope 36.2 Hz to 73.53 Hz

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oTracker

• Designed to use digital sensor inputs (line
  followers) to determine the location of a black
  line on a white background
• Formats URCP readings to express how much it
  needs turn
• Range of values /-8, /-16, /-24, /-32
• Maximum of four sensor inputs

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Key Points using oTracker

• Setting the Width property to 1 allows the use
  of only three sensors
• Range of values /-8, /-24, /-32 (no /-16)
• The fourth sensor was used to detect the inner
  circle with an oEvent

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oNavCon

• Coverts the information received from oTracker
  into motor control speed for the servos
• Takes the predetermined Speed value then adds
  or subtracts the values received from oTracker
  (URCP values) and send them to the servos

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Key Point using oNavCon

• Set oNavCon to 0 to turn off the line following
  subroutine
• This allowed us to turn off or override the line
  following subroutine to make adjustments for a
  special event

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oCompare2

• Used with the sonar sensor
• Triggered depending on distance
• Compares two numbers (predetermined upper and
  lower limits) and sets the servo speed values to
  follow a along a wall or go around a box

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Basic Flow Diagram
Line following (oTracker)
oNavCon on
oNavCon
oNavCon off
oNavCon off
Inner Circle (oEvent)
Go around box (oCompare2)
Wheels (oServoSP1)
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Competitions 1 2
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Round 1 of Line Following Competition

• Objective To complete three laps around the
  black line track where one lap must be around the
  outer loop of the track.

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The Line Following Sensors
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The Line Following Circuit

• The circuit for an individual line-follower
• Pull-Up Resistor 10 kW
• Rf Resistor 220 W
• Line follower Capacitor 0.1 mF

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Complete Line Following Circuit
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The Line Following Printed Circuit Board
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Capacitors Used in Line Following Circuit Board

• We found documentation explaining how capacitors
  could be included in the line following circuit
  to reduce noise that the line followers may pick
  up.
• The capacitors are connected to the line
  followers in hopes of leveling out the ripple in
  the signal out.

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No Significant Difference

• We tested the Trekker with, and without the
  capacitors in the circuit
• No significant difference was found.
• Therefore we chose to remove the capacitors from
  the line following circuit board.
• Our design of the circuit board made removal of
  the capacitors easy, as they were connected from
  behind using free wires
• These wires were cut, electronically removing the
  capacitors from the circuit

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Direction of Travel Around the Track
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Servo Values S4 and S5

• The coded values of S4 and S5 refer to server
  rotational speeds
• S4s value directly corresponds with the Right
  Wheels rotational speed
• S5s value directly corresponds with the Left
  Wheels rotational speed

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Finding the center of the servos rotational speed
values

• From Trekker Experiment 3
• S4 and S5 relationship with the rotational speed
  of the wheel was found

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Left and Right Wheel Speeds are not the same
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Reversal of Direction

• Because the left servo and the right servo are
  opposite of each other, they each travel in
  opposite directions relative to one another
• To remedy this, one of the servos values is
  inverted
• Now both wheels will move the Trekker forward at
  the same time.

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First Competition Program Works!!

• The initial line following program was uploaded
  to the OOPic R.
• The Trekker successfully went around the outer
  loop of the track
• First run around the track was very slow

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Improvements to Program

• Had to find a good value for the servo speeds
• Not too slow, or the Trekker would take too long
  around the turns. It would have a very jerky
  stop and go manuever.
• Not too fast, or the Trekker would leave the
  black line on the turns and not return.
• A speed value of 31 was found to be the best for
  what we needed

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Number of Line Following Sensors

• The more line following sensors employed in the
  design, the faster the Trekker should be able to
  traverse the course
• Using Four Sensors
• Time around track 1 min 6 sec
• Using Three Sensors
• Time around track 1 min 5 sec
• Three sensors are used in the final design of the
  Line Following program

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Three Outer Loops, no Inner Loops

• Our Trekker made it successfully around the outer
  loop of the track three times.
• No inner loop attempt was made

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Round 1 Line Following Competition Results

• Best time around the track
• 0100.75
• Competition Ranking
• 4th Place overall
• 8 Points awarded

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Round 2 of Line Following Competition

• Competition Objectives
• To complete three laps around the black line
  track
• One lap around track must be upon the outside
  loop
• Group Objectives
• To complete two laps around the inner loop of the
  track
• Make a better time around the track three times
  than in Round 1 of the Line Following
  Competition

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Line Following and Inner Track Sensors

• Line Following Sensors
• Three used, as were used in the Round 1 of the
  competition
• Inner Track Sensors
• One was used away from the three Line Following
  Sensors

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Direction of Travel and Inner Loop Sensor
Placement

• Direction of Travel around track
• Clockwise
• Placement of Inner Loops Sensor
• On the left side of the Trekker when facing the
  Trekker front first.

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Line Following and Inner Loop Sensor Placement
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Outer Loop Behavior

• For the first lap, the Inner Loop Sensor will
  record each time it passes over the inner loop.

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Inner Loop Behavior

• After the first lap, and the inner sensors having
  noted the inner loop twice.
• Every time the inner loop sensor notices a black
  line the Trekker will turn to the right, and take
  the Inner Loop around until it finds the opposite
  side of the track on the Outer Loop

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Testing and Improvements

• We needed to make the Trekker have smoother turns
  around the corners of both the outer and inner
  loops of the track
• This was done by changing the coded values for
  the right servos center, the left servos
  center, the oNav.Center, the LeftServo.Value, the
  RightServo.Value, and the overall speed of the
  Trekker

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Results of Testing and Round 2 of the Line
Following Competition
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Round 2 Line Following Competition Results

• Best time around track
• 050.51
• Competition Ranking
• 3rd Place Overall
• 18 Points Awarded

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Competition 3
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Round 3 of Line Following Competition

• A familiar problem
• Recognize Inner Loop
• Recognize Tool Box
• Line Follow once outer Loop, and twice inner
  Loop
• Oh, and navigate at most 8.5 inches from Tool Box

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Tool Box Solution

• Hardware
• Devantech SRF04 Ultrasonic Range Finder
• HiTec HS-311 Servo

• Objects to utilize hardware
• oSonarDV
• oServoSP1
• oCompare2 Properties (Above,
  Below and Between)

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The Set Up

• 1st oCompare2.Input set to oSonar.Value
• 2nd ReferenceIn1 set to Lower oSonar.Value 53
  and ReferenceIn2 set to Upper oSonar.Value 58
• 3rd Allow oCompare to call Sub Routines to
  maintain 8.5 inches from tool box

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Sonar

• Operation of Sonar device
• Maximize sample rate. How? (Link Sonar.Operate to
  OOPIC.HZ60)

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SRF04 Timing

• Need to toggle at a rate that sonar needs to
  monitor

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SRF04 Graph
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Function of Sub Routines

• We had Four Sub Routines
• Flag Inner Used differently than previous
  competitions.
• Above - Servo control to turn left.
• Below Servo control to turn right.
• Between Servo control to go Straight
• Note Each Sub controlled operation of oNavcon

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Competition Day

• What Happened?
  A) Failed to detect object consistently B)
  When oCompare operated, Sonar Servo lost sight of
  object and Our Left Turn Sub routine was called.
• Possible Solution
• A) First Right Turn was a hard turn, we needed
  a set up sub routine and a means to return to
  line follower.
• B) Improve Sonar Performance.

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Overall Results

• Completed two of the three competitions.
• Placed 2nd in the class overall.
• Project was a success overall

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Conclusions

• What we learned
• The importance of working as a team.
• Using indicators in a circuit to help with
  troubleshooting.
• Integration of external devices with a
  microcontroller.
• Data sheets are helpful in design and
  implementation.

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Conclusions Continued

• What we learned
• How an infrared sensor, a sonar sensor, and
  optical sensor work.
• Utilization of these devices to accomplish an
  objective.

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References

• OOPic Manual. Retrieved from http//www.oopic.co
  m/.
• Trekker Robot. Retrieved from http//www.superdr
  oidrobots.com/shop/.