The document describes the design of a precision Rangoli maker robot called the Rang-bot. It consists of three main parts: 1) The robot body frame that uses two stepper motors to move a color dispenser in the x and y axes within a 60cm area. 2) A microcontroller and software that takes an image as input, converts it to G-code, and controls the stepper motors. 3) A color dispenser mechanism that uses a geared DC motor to regulate the flow of powdered color through a nozzle. The document provides details on the components, design, and working of each part, with the goal of creating automated rangoli drawings from input images.

1. The Rang-bot

2. The Rang-bot
Precision Rangoli Maker

3. OUTLINE
1. A small Description of Rangoli Maker
2. Components of the robot
3. The Robot - Main Body
4. The softwares and Microcontroller
5. The Colour dispenser

4. Some concepts we need to learn :
A. CNCs
What we are essentially trying to construct here is a CNC or computer numerical control machine.
CNC machining is a manufacturing process in which pre-programmed computer software dictates the
movement of factory tools and machinery. Using this, we can accomplish several complex 3D/2D
cutting and printing tasks with a single set of prompts. The language behind CNC machining is
alternately referred to as G-code, and it’s written to control the various behaviors of a corresponding
machine, such as the speed, feed rate and coordination. In today’s CNC protocols, the production of
parts via pre-programmed software is mostly automated. The dimensions for a given part are usually
set into place with computer-aided design (CAD) software and then converted into an actual finished
product with computer-aided manufacturing (CAM) software. However, for our purposes, we will not
need these CAD or CAM as we are merely creating a simple 2D model, which we can easily convert to
G Code and input into our arduino.
Speaker : Narendra Kumar

5. B. G Code
G-code, or “geometric code”, is a programming language for CNC that instructs machines where and
how to move. Most machines speak a different “dialect” of g-code, so the codes vary depending on
type, make, and model. G-code follows some variation of the alpha numeric pattern: N## G## X##
Y## Z## F## S## T## M##, where N is the Line number or which line of the 2D model we are at (for
indexing) , G is the Motion, i.e. how fast the nozzle moves or in what pattern (Circular, straight, etc.),
X, Y and Z are the destination coordinates, F is the Feed rate, for defining the surface speed of the
cutting tool in inches per min, S is the Spindle speed, which is the rotational speed of the cutting tool in
revolutions per min, T is the Tool selection, to select which mill or lathe to use, and M refers to the
Miscellaneous functions like coolant, spindling, etc. We will not need all of these functions for our
purposes (Just flow rate, motion type and X and Y coordinates), however most G-Code implementing
machines require all these parameters. We will be using the in built Arduino G-Code library, linked
here- https://create.arduino.cc/projecthub/tinkersprojects/g-code-arduino-library-
1a2bd6#:~:text=G%2Dcode%20is%20a%20set,saved%20on%20an%20SD%20card.

6. About Rangoli Maker
The Rang-Bot
The Rang-Bot is a robot which can draw a
uniColoured rangoli over a particular area.
It takes an image of rangoli as input and
reproduces the same on a plane floor. For
that we have created a novel design which
is cost efficient, precise and robust.

7. Bot Specifications
1. dx = 0.0055 mm, dy =1.177 mm ( dx is distance traveled by nozzle in x direction with stepper
motor moving a minimum angle.)
2. Drawing space of 60 cm * y where y is at least 5 mm.
3. Orifice diameter of powder dispenser is 5mm.
4. Power consumption : 22 W (may vary).
5. Battery backup for continuous use : 1 - 2 Hrs (May vary)
6. Robot Dimensions : 47 cm * 108 cm * 57 cm

8. Components 1. The Robot - Main Body
2. Microcontroller and
Softwares used
3. Colour Dispenser
Our Whole system consists of 3
major Parts.
In next slides, we will talk about the following of each
of the above mentioned parts.
A. Purpose
B. Component used
C. Model
D. Working
Speaker : Yogesh Yadav

9. Block Diagram
Scan2CAD Vector Image Scan2CAD G code file
To steppers
and servos

10. 1. The Robot -
Main Body
A. Purpose
For drawing a rangoli, this is the main
frame of hardware used to move the colour
dispenser in a 2d Plane. It consists of two
stepper motors which will move the
dispenser in x axis and y axis
independently. It allows the colour
dispenser to move within a width of 60cm.

11. B. Components Used
S.No. Description Specifications Quantity
1 Stepper Motor Nema17 4.2 Kg cm 2
2 Wheels Diameter 15cm 2
3 Steel Rods L=750mm, 10mm ⌀ 3
4 Threaded Rod L=750mm, 10mm ⌀, Pitch = 1.5mm 1
5 Ball bearings 10mm,10mm ⌀ (inner) 6
6 Caster Wheels 4cm 4
7 Gears 25 mm, 50 mm 2 each
8 Cylindrical Ball bearings 10mm ⌀ (inner) 2
9 Hex Nut 10mm ⌀ (inner), Pitch = 1.5mm 1

12. C. Model
a. Isometric view b. Top
view

15. D. Working
The model has similar working as any other CNC
machine. The nut attached on the dispenser is
constrained to move along the rod and the rods are
constrained to move with the bot guided by the
wheels. Hence, we have two steppers to move the
dispenser in a 2D plane. We can see that there is no
bound to y- axis. Our model can cover up a area of
60 cm *y where y can be any length greater than dy
i.e. 0.117mm. The steel rails are used to guide and
support the dispenser to move along x-axis. We
have used a gear system of torque gain of 2 which
will increase the precision and power of the bot
along both axis. We have also used caster wheels
to support our bot from toppling.

16. 2. Software part
and
microcontroller
A. Purpose
The main goal we wish to accomplish
with the software portion of our model is
to convert our picture from its JPEG
format to a G-Code format. From here,
we can input this G-Code into our
microcontroller to use the motors to
create a final rangoli.
Speaker : Parth Bajaj

17. B. Components Used
S.No. Description Specifications Quantity
1 Microcontroller Arduino UNO 1
2 Lipo rechargeable battery 11.1 V 2200 mAH 1
3 Stepper Motor drivers A3967 Microstepping Driver 1
4 Stepper motor Nema 14 2
5 Jumper Wires - -

18. Components

19. C. Circuit for single axis

20. D. Working
Software- The G-code we will use for our purposes has just 4 parameters- G## X## Y## F## where, G is the
Motion, i.e. how fast the nozzle moves or in what pattern (Circular, straight, etc.), X and Y are the destination
coordinates and F is the Feed rate, for defining the surface speed of the dispensing tool in inches per min. The
main functions we will use are G00 X## Y## F## or G90 to set- Absolute mode, where the dispenser dispenses
in a line with flow rate F to the destination (X,Y), G01 X## Y## F## or G91 to set- Relative mode, where the
dispenser moves (X,Y) amount from the current position at speed F, G04 P##, where the CNC will do nothing
for P seconds, G92 X## Y##, where the dispenser will move to (X,Y) and G02 X##Y##I##J## for clockwise and
similar G03 for counterclockwise arcs, where I and J are the relative coordinates from the start point to the
center and X and Y are the endpoints.

21. D. Working
To actually convert our image to G-Code, we would first have to convert the raster image into a vector one.
This can be done manually by sketching along the boundaries of the image, however certain online converters
definitely save a lot more time. After this, our G-Code would be generated by starting at any vector (Usually
(0,0) or center) and tracing each vector using the relative move mode. If we reach a point that has already been
completed, we can search for any unfinished vectors in the image and move our cursor there and start again.
The basic idea here is to trace all the vectors in the image. Realistically, we were planning on using a software
like Scan2CAD to directly vectorize and generate G-Code for our JPEG image.

22. D. Working
Microcontroller- Once we obtain our G-Code, we need a program that allows us to input that to our
arduino. This program will be in C++ and have 5 main functions-
1. Setup- To setup the controller, put initial position to (0,0), set a default flow rate and open coms.
2. Loop- To be run continuously once setup is complete, whose purpose is to read a command,
store it and call the function that processes your command.
3. Process command- It searches for the G value and calls either line or arc depending on the
command. It can also call the position function to position the dispenser or to wait for a given
amount of time, or even tell the current position of the nozzle.
4. Line- This is a simple function that can be used to create a line, depending on which mode is
active. For this, we use m1step and m2step functions which are inbuilt in arduino library to move
the motors to create the required line.
5. Arc- This is a similar function as line, used for creating arcs. It finds the angle and radius of the
arc and breaks it up into small lines, which it then creates.

23. D. Working
Auxiliary functions-
1. ParseNumber- For finding number after code (G23 would return 23 if searching for G value)
2. Help- Displays options
3. Where- returns the current position of nozzle
4. Ready- Creates ready state at the start of every loop
5. Output- Prints a string (For debugging)
6. Atan3- is the inverse tan of a given dy/dx ( Accounts of negative angles also)
7. Position- Repositions nozzle
8. Feedrate- Sets a Feed Rate
9. Pause- Takes a break, eats a kitkat.
Source code-
https://github.com/MarginallyClever/GcodeCNCDemo/blob/master/GcodeCNCDemo2Axis/GcodeCNC
Demo2Axis.ino

24. 3. Colour Dispenser A. Purpose
This is the nozzle system we use to
dispense the colour stored. We analysed
that color drop is not simple achieved just
through a simple opening. So we created a
mechanism to control the flow of colour in a
better way. It will help us to regulate the
flow of colour smoothly without any
glitches.
Speaker : Mrinal Mahato

25. B. Components Used
S.No. Description Specifications Quantity
1 Geared DC motor 10 RPM, 12 V 1
2 MOSFET N-Channel MOSFET 60V 30A 1
3 Resistor 10k ᘯ 1
4 Diode Rectifier 1A 50V 1
5 Push Button for manual cleaning Generic 1
6 Rangoli Colour Generic 200gm
7 Twisted plate 50mm 1
8 Ball Bearing 10mm,10mm ⌀ (inner) 1
9 3D printed bottle Autocad model attached 1
10 3D printed solid Frame structure Autocad model attached 1

26. Circuit Components

27. C. Model
3D Dispenser Model
3D modified bottles
for different colours
Geared DC motor
Dispensing
Mechanism

29. D. Working
The Colour is fed into the main chamber of the dispenser
from a container with powder above it. This main chamber
is fitted with a screw inside, the head of which is attached
to a geared DC motor located right outside the main
chamber. When this turns, the rearmost groove of the
screw fills with Colour and the frontmost on pushes that
Colour out of the nozzle. If the motor is turned faster, it
increases the flow rate. With this design, we are able to
lower the size of orifice which will help us to increase the
precision.

30. Final Model and Circuit

32. Extensions
We can extend this by allowing it to create multi-Coloured images. How this can be done is by using
image processing techniques to isolate the two Colours and vectorize both those images separately.
This will create two layers, and when we generate the G-Code for both of these, putting a pause
function in between, that will allow us to detach and clean the dispenser and replace the Colour on
top, without disturbing the Rangoli. After this, we reset the nozzle to (0,0) and print a second layer.
This will allow us to create multi-Coloured rangoli, as we can extend this to n Colours.
Speaker : Parth Bajaj

33. Origin
Reference on Ground

34. Thank YOU!