Electromechanical Systems
“Robotic Sorting System”
Brent Guy Jonathan Penney
ObjectivesObjectives
• 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 EvolutionDesign 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
HardwareHardware
PIC Microcontroller
• 40-pin 16F877 embedded chip• Provides analog to digital conversion• Sends pulse waves to control servomotors
HardwareHardware
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)
HardwareHardware
SSC-32 Servo Controller
• Integrated circuit board that controls servos• Servos plug into respective channels• Reads converted digital inputs from PIC
HardwareHardware
MAX232 Converter
• Adjusts voltage of signals so communication 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
HardwareHardware
IR Proximity Sensor
• Panasonic sensor with 2 LEDs• 4 – 26” range• Sensitivity adjusted by potentiometers• Information digitally sent to PIC
SoftwareSoftware
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 ScreenshotRIOS Screenshot
Programming a ServomotorProgramming a Servomotor
Format:
• # <Motor> P <Units> T<mSeconds>
- E.g. #0 P1000 T3000
Moves motor 0 to position 1000 in 3 seconds
Pseudo CodePseudo 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 DemonstrationRobot Demonstration
DifficultiesDifficulties
• Missing link parts
• Faulty servomotors
• Short wires required splicing
• Friction of base plate (removed 3 spokes)
• Power source
RecommendationsRecommendationsFuture 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
ConclusionConclusion
• Assembled Robot• Programmed• IR Sensor• Shelf Construction
• Resulting in a functional robot that
detects and transports test tubes for the biomedical industry
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