Ball Man
By Vivek Manoharan
TAs: William Dubel
and Steven Pickles
Problem/Solution
Microcontroller
• Atmega128
• SparkFun AVR board
• 16 MHz ext. crystal
Behaviors
• Locate – CMU Cam to locate tennis ball
• Ping/Center – Ultrasound to center ball for mechanical arm retrieval
• Retrieve – Pickup tennis ball
• Return – CMU cam searches for bright orange
CMU Camera
• Detect contrast level of tennis ball on tennis court
• Initialization of color required
• Allows for differently colored tennis balls to be located
White Balance Indoors
• White Balance off
White Balance Indoors
• White balance on
Ultrasound Sensors
• Determine whether objects are on the tennis court
• If CMU camera RGB values do not match that of tennis ball, obstacle avoidance is initiated
• If there is a match, retrieval system is called upon
Devantech SRF-04’s
Mechanical Arm
• Timing used to determine when to stop “push”
• Use a high torque DC motor to lower and hoist mechanical arm
• Places ball into container
Mechanical Arm
Mechanical Arm
Other Parts
Research/Findings
• CMU resolution is very limited
• Interaction of independently working behaviors is extremely frustrating
Findings
Future Work
• Use a better motor driver for control of all 3 motors (two wheels and one arm)
• Create a “dropping off” mechanism
• Allow communication to a remote computer indicating how many balls have been retrieved
Conclusion
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