Automated Colored Balls Sorter

Presented By:

Mihir Daftari

Ka Fai Ng

Woo Jin Park

Project Description

Objective Applications

Papers Textiles Metals

How does it work?

System Connections

C328-7640 JPEG Compression VGA Camera Module

Camera Details: Low-cost ($47) & low-

powered (3.3V) and very small in size

RS-232 interface: A wide range of baud rates ranging from 9600 to 115.2K bps for transferring images

Built-in color conversion circuits for 4 gray/16 gray/256 gray/12-bit RGB/16-bit RGB images.

Auto detect baud rate and make connection to the host

Camera operations and features

On-board EEPROM provides a command-based interface to external host via RS-232.

A RS-232 transceiver set-up has to be used as communication interface. The MAX3232CUE chip is used.

The command set

Command protocol to take an uncompressed snapshot

Sample picture taken at 640X480 resolution

Sample picture from the camera

The picture is displayed using the MATLAB ‘imshow’ function.

Details: Resolution: 80 x 60 Color type: 12 bit color 4

bits for Red, 4 bits for Green and 4 bits for Blue

Total Size: 7200 bytes

Sample picture .. This is a picture taken of a

red ball on a black background (a black binder here)

This is the type of image that is expected to be seen in the project.

Color detection algorithm will be run on this type of images.

It takes less than 6 seconds to transfer the entire image from the camera to the host.

Vector distance algorithm for color detection

Lets say we are searching for “green” color. Pure green exists when the values of the pixels are R = 0, G = 255, B = 0.

The pixel we took in is a vector

Pixel = [R G B]

The eculedian distance between those 2 vectors is

D = sqrt((R-0)^2 + (G-255)^2 + (B-0)^2)

Code

So the algorithm goesfor each pixel { 1. compute the distance between that

pixel and the reference color (D) 2. if D<Threshold then current pixel is accepted

else current pixel is NOT accepted

}

Threshold

"Threshold" is a constant value and has to be set manually according on the "tolerance" desired for application (a high value of Threshold means that less "clear" green pixels will be considered as green, whereas a lower value of Threshold will make the algorithm quite "strict")

Actuator

Stepper Motor Precise positioning High static torque for blocking the ball from moving toward the

camera Rotate 90º at 7.5º per full step (12 steps) Half-stepping method (24 steps) to eliminate stiff movement of

Full-stepping method

Stepper Motor Controller

1B3

2B6

3B11

4B14

1C2

2C7

3C9

4C16

CLMP11

CLMP28

U1

ULN2064

HCS12

B3B2B1B0

Coil DCoil CCoil BCoil A

Stepper Motor

5V

Power

ULN2064 – Quad Darlington Switches

Commands and Step Sequence

Commands RCW: Rotate

counterclockwise 90º Pause: Step motor stops Resume: Step motor

resumes rotational movement

When pause activates, motor will pause after the last RCW is finish executing

Allow future expansion or additional commands

Sample Step SequenceStep Number Coil A Coil B Coil C Coil D

1 1 0 0 1

2 1 0 0 0

3 1 1 0 0

4 0 1 0 0

5 0 1 1 0

6 0 0 1 0

7 0 0 1 1

8 0 0 0 1

Ball Dispensing Mechanism

Motor arm pushes one ball at the bottom of the tube

Next ball falls after previous ball has been pushed out

User Interface:GUI & Commands

Serial CommunicationRS-232Javax.comm package

Default Commands:Start SystemStop System

Override Commands:Pause SystemResume SystemClear

Proposed Bit Patterns

Commands Bit Pattern (8 bits) Commands10000000 Start01000000 Stop00100000 Pause00010000 Resume00001000 Clear Balls

Status Bit Pattern (8 bits) System Status00000100 Running00000010 Paused00000001 Stopped11111111 Error

Operating Conditions

Uniform black background Single colored ball Brightly lit room Size of the ball

Potential Difficulties

Jamming of balls “Extreme” shades of red, green or blue might not be

detected Poor lighting conditions Motor controller overheats

Budget

DEMO

Questions?