ENGI 4933 “Robotic Sorting System” Brent Guy Jonathan penney

loutclankedAI and Robotics

Nov 13, 2013 (3 years and 6 months ago)

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Electromechanical Systems


“Robotic Sorting System”


Brent Guy


Jonathan Penney


Objectives


Design a robotic sorting system



Construct a routine to locate test tubes



Ignores locations if shelf is empty



Transport them from storage shelf to desired
location



Design Specifications

Robotic arm has 2 major limitations:




Rotational limits



Height constraints


Size of shelf compartments


Weight of test sample


Design Evolution


Robotic arm with RGB sensor


9 compartment shelf design


Puts samples on shelf



Robotic arm with IR Sensor


3 compartment shelf design


Takes samples from shelf



Hardware

PIC Microcontroller



40
-
pin 16F877 embedded chip


Provides analog to digital conversion


Sends pulse waves to control servomotors

Hardware

Servomotor



Pulse
-
proportional servos move the links


180 degree range of motion


Positions are based on incoming pulses




-

2500 units = 2.50 mS pulse




(1 unit = 0.09 degrees)

Hardware

SSC
-
32 Servo Controller



Integrated circuit board that controls servos


Servos plug into respective channels


Reads converted digital inputs from PIC


Hardware

MAX232 Converter



A
djust
s

voltage

of signals so

c
o
mmunication
can take place

between PIC and SSC
-
32


SSC
-
32:
-
10 V for logic one, +10 V for zero


PIC: +5 V for logic one, 0 V for zero

Hardware

IR Proximity Sensor



Panasonic sensor with 2 LEDs


4


26” range


Sensitivity adjusted by potentiometers


Information digitally sent to PIC


Software

RIOS



Allows user to configure servos


Define positional limits of servos


TTY



Provides direct serial communication


Allows for quick alterations


* Final code produced in C



RIOS Screenshot

Programming a Servomotor

Format:



# <Motor> P <Units> T<mSeconds>



-

E.g. #0 P1000 T3000



Moves motor 0 to position 1000 in 3 seconds

Pseudo Code


Set Initial Position


Scan A


If object present, grip and drop


If not, continue to B


Scan B


If object present, grip and drop


If not, continue to B


Scan C


If object present, grip and drop


If not, Set Initial Position

Robot Demonstration

Difficulties



Missing link parts



Faulty servomotors



Short wires required splicing



Friction of base plate (removed 3 spokes)



Power source

Recommendations

Future Use



Keep robot within suitable range (cannot move shelf
without re
-
programming)


Infrared sensor has trouble detecting transparent
tubes


Improvements



RGB sensor


Add movement for transportation


Wheels


Track

Conclusion


Assembled Robot


Programmed


IR Sensor


Shelf Construction



Resulting in a functional robot that


detects and transports test tubes for the
biomedical industry