Robot-Sketcher-5-bar-parallel-manipulator-(feel free to use and contribute)

An amazing robot sketcher based on the 5 bar parallel manipulator mechanism(SCARA)

OVERVIEW OF THE PROJECT

• Used python programming to solve the inverse kinematics equation of the mechanism, to do processing of all the co-ordinates of a given image and used atmega328p microcontroller with A4988 drivers to control the stepper motors which control the links/arms of the robot.
  
• Developed an algorithm to make the robot able to use gcode in python and fill the missing coordinates to maintain desired level of smoothness of lines/curves drawn.
  
• Developed an algorithm to keep track of the error in the movement of the links occuring due to resolution limitation of the stepper motors and the motor drivers.The algorithm also tries to correct the error with each input coordinate without the use of close loop control(means not encoder senssors necessary). The prevent the accumulation of error and keeps the error in the movement of the end effector minimum.
  

Demo

• Watch on Youtube https://www.youtube.com/watch?v=lMgfEUtLZQk

Pre-reqsuisite knowledge

• 

• To understand the kinematics of the mechanism visit: Here

• The "robot_main.py" runs on the computer and "robot_arduino.ino" is for the arduino

HARDWARE REQUIRMENTS

1. Arduino Uno

2. CNC shield (like the one at :https://www.electronicscomp.com/cnc-shield-v3-3d-printer-a4988-expansion-board?gclid=EAIaIQobChMIlLCC3vCO4gIVlQsrCh2Urw_xEAQYAiABEgL_j_D_BwE)

3. Two Stepper motor

4. Two stepper motor drivers(Model: A4988)

5. 12V adapter

6. Plywood/Aluminium or whatever you use to make the links

7. Bearings(optional;the first version if this robot had links joined using nut and bot and it worked pretty fine)

SOFTWARE REQUIRMENTS

1. Python 3.6(and for library requirments see "robot_main.py" file)

2. Arduino IDE

3. Inkscape for making vector image

4. For vector to g-code visit: jscut.org

Note: while making vector image using inkscape make all dimentions in mm also make sure the drawing is on the positive x and y axis. because the python program neglects negative coordinates.The image can be shifted to the negative axes of the robot's workspace by assigning shifts in mm to "xerr" and "yerr" variable in the main python program.