EEL 5666: Intelligent Machine Design Laboratory

1
EEL 5666 Intelligent Machine Design Laboratory

• Final Presentation
• by
• Rob Hamersma
• April 12, 2005

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µCHIP

• Micro-Controlled High-tech Independent Putter

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Introduction

• Project goal Develop a robot that can play
  miniature golf autonomously.
• Main functions
• Locate and approach golf ball
• Locate hole and turn to face it
• Determine the distance to the hole
• Strike the ball with the appropriate force to
  sink the putt.

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Main System Components

• MAVRIC-IIB board with ATmega128
• 2 - 12V, 44 rpm DC gearhead drive motors with
  caster wheel
• 1 7.2V, 175 rpm DC gearhead motor for putter
  mechanism
• 2 mechanical bump switches with extended wire
  actuators
• SRF04 ultrasonic range finder
• CMUcam color digital camera
• Hitec HS-303 standard servo for camera tilt
• 7.2V NiMH battery pack

5
Original Platform Design

• 2 drive wheels with caster for balance
• Bump switches
• Putting surface centered behind wheels
• Camera mounted in front above ball

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Final Platform Design
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Design Changes

• Motorized putter vs. driving into the ball
• Drive motors need to be slow to position the ball
  and find the hole but fast to putt.
• Sonar instead of IR for obstacle avoidance
• No sonar for ball positioning or hole distance
  detection
• Needed slower motors with more torque

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Obstacle Avoidance

1. SRF04 ultrasonic range finder (sonar) detects
   objects at a distance
2. Drive motors start turning in random direction
3. Sonar determines if it is moving away from or
   closer to the object
4. Drive motors correct turn direction if necessary
5. If too close to object, stop and spin until way
   is clear
6. If bump switch pressed, stop, back up, and turn
   away from object

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Mini-Golf Behavior

1. Spin around with camera at 40º, then 20º
2. Drive towards ball avoiding obstacles
3. Center ball between drive wheels using camera
4. Look up and spin to locate hole with camera
5. Calculate distance to hole by computing the size
   of the ball in pixels
6. Look down and readjust ball position with LEDs on
7. Putt ball into hole with appropriate speed

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Special Sensor CMUcam

• Used to
• detect red golf ball on green turf
• center the ball between the drive wheels using
  servo to follow ball
• locate the hole (larger red ball mounted over
  hole)

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CMUcam Operation

• Uses raw mode to process incoming data easily
• Used polling mode at first, now parses streaming
  with receive interrupt
• Uses RGB mode to find hole marker and YCrCb mode
  to find ball (less susceptible to changes in
  illumination)
• Uses bounded box data rather than pixel count to
  determine size of object
• Uses color, size, and confidence level to
  recognize ball
• Uses color, y-position, and confidence level to
  recognize hole marker

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Putting Speed Analysis

• Measured minimum putting speed at various
  distances and ran a simple regression
• Formula 0.03x² - 3.2x 125

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Conclusions

• µCHIP meets all of my original design objectives
• CMUcam works well with adequate lighting (YCrCb
  mode helps)
• As far as motor selection slower (with torque)
  is better for precision and positioning