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