This is my internship report in Drona Automation, where I received tremendous opportunity as an Intern Design Engineer. Over the course of the internship, I had cultivated and developed my engineering skills like idea generation, problem-solving, design/model/analysis of sewage robots, working with 3D printers, additive manufacturing, etc.

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SCHOOL OF MECHANICAL ENGINEERING
Internship Report
On
DESIGN, MODELING AND ANALYSIS FOR AUTOMATED
SEWAGE CLEANING ROBOTS
Submitted by
Mr. SIVA S
SRN: R19MMD07
Third Semester M.Tech. (Machine Design)
Carried out at
Drona Automations Pvt. Ltd.
From January 2020 to December 2021
Rukmini Knowledge park ,Kattigenahalli, Yelahanka, Bengaluru-560064
www.reva.edu.in

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INTERNSHIP CERTIFICATE

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SCHOOL OF MECHANICAL ENGINEERING
CERTIFICATE
Certified that the internship work entitled “AUTOMATED SEWAGE CLEANING ROBOTS
FOR HORIZONTAL AND VERTICAL PIPES” carried out by Mr. SIVA S, R19MMD07, a
Bonafede student of REVA University, is submitting the internship report in partial
fulfillment of the requirements of 3rd
semester of Master of Technology in Machine Design
under Mechanical Engineering during the academic year 2020–21. The dissertation report
has been approved as it satisfies the academic requirements in respect of Internship
prescribed for the said degree.
Dr. Niranjan Hiremath
PG-Coordinator
Dr. K.S.Narayanaswamy
Director

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CONTENTS
Sl.No
Particulars
Page No.
1 History of the company 5-6
2 Vision of the company 7
3 Clients and Products/Services 8-9
4 Details of Training Undergone 10-15
5 Relevance to the academics
(New Knowledge acquired)
16
6 Conclusions 17
7 References 18

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INTRODUCTION
History of the company:
Drona Automations Pvt Ltd is a startup company initialized in the year 2019 which has
primary aim is to eradicate inhuman practice of manual sewer cleaning with automatic
sewer cleaning robots. The CEO and Founder of Drona Automations is Mr. Suraj N, an
alumni of REVA University who laid foundations for this solution behind the issue.
Initially the setup was established with the aid of REVA University to encourage the new
idea as reality. With constant effort and unique solutions provided by Drona Automations
paved for better exposure and funding. With the current scenario the Drona Automations
has been independently functioning at Yelahanka, Bangalore, with team of small and
encouraging members.
Fig 1. Drona Automations Logo and its Tagline
With efforts from students of mechanical and electronics departments of REVA University the
first Manhole Sewage Pipe Cleaning Robot (MSPCR-1) came to light. MSPCR-I had been
tested in the laboratory by using a manhole test rig that simulates realistically the actual
environment and conditions encountered in real-life manholes. Tests such as the motor drilling
speed optimization test, clamping action test, and robot dynamics tests had been carried out to
ascertain the practicability of the robot.
Also, the robot has been tested in real-time conditions by selecting a manhole inside the REVA
University campus under different conditions. These experimental tests had given them
valuable insights for improving the robot further. Reduction of set-up weight by using
aluminum and other composite substituting metallic parts with plastics and other alternatives
wherever possible, reduction of overall length of the robot. Also providing optimum ground
clearance are the major improvement points envisioned.

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Fig.2. Pitched ideas to few Japanese delegates at REVA University campus
They are projecting an investment to the tune of about 2.5 crores for a period of one year. With
selling price of these robots well within 10 lakhs, which is significantly lower than robots
currently sold by other vendors in the country.
Fig. 2 First fully functional sewage cleaning robot

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VISION OF THE COMPANY
• To provide solution to the societal problems from sewage to space
• To build a company as the prominent player in the field of Automation with global
standards
• To use technology for developing products considering ethical values.
• To create space for students in production, research and innovation
Fig 3. Traditional Inhuman manner of sewer cleaning
Drona Automation aims at eradicating the traditional inhumane manual sewage cleaning with
replacing by automated robots to cleanse the sewage system at affordably low cost.
Simultaneously they indent to focus in automation from sewage to space fields parallelly. This
approach cannot be done only with the help of industries and partners, so they indent to provide
training, internships at their company for professional students to help them improvise
practically by exposing them to industries and retain some fresh ideas from them, where both
get benefited mutually.
Their upcoming plans are to expand their technical team more diversely with Electronic
Engineers and Mechanical Engineers who possess strong engineering skills. As their products
improvise over time, they plan to include the AI aid to serve its purpose relevance purpose in
the automated sewage cleaning by robots. Although various competitors have similar robots,
they tend to lag in cost wise i.e., the cost of the robots are exponentially high.

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CLIENTS AND PRODUCT SERVICES
Clients and Partners:
1. Industry Partners:
• NAABHYA Interconnect
• Bholanath
• NSK Electronics
• NE Robotics
• SS Tools & Technology
2. Academic Partner:
• REVA University
3. Government Partners:
• KSCST (Karnataka State Council for Science and Technology
Products:
They have robots which will clean the sewer pipes from manhole sewer pipes of 12 inches
till smaller sewer pipes of 4inches.
The following three high market value products proposed are:
a) Manhole Sewage Pipe Cleaning Robot (MSPCR-I)
b) Vertical Sewage Pipe Cleaning Robot (VSPCR-I)
c) Horizontal Sewage Pipe Cleaning Robot (HSPCR-I)

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Product Services:
1. Sales of Customized Robots:
They design, manufacture and sell customized robots as per requirement of the
customers.
2. Service of Robots:
They offer servicing of HR/VR robots and other automations systems of Drona’s
product.
3. Providing solutions to day to day problems:
They will offer solutions through automation system and service to your problems,
Fig. 4 Illustration of HSPCR-I robot, functioning in a clogged pipe
Fig 5. Illustration of a fertilizer drone and a sanitizer humanoid robot

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DETAILS OF TRAINING UNDERGONE
1. Design and Modelling from CATIA_V5:
Initially myself and my intern teammate Ms. Shikha N Singh were assigned to model
components that were needed for version_1 robot. While assuming all the clearance and
data collection, appropriate nomenclature for the parts were assigned. The nomenclature
consisted from robot movement, part number, revision number and that particular revised
date. Ex: HR.3549.5.25
Learnt assigning the material generation from Material Library section in CATIA and
enclosing various material characteristics and surface characteristics.
Ensuring the Center of Gravity (CG) is always placed at right spot by shifting
parts/reduction in material is some region or addition of counter weight.
Fig 6. Some of the elecronic components selected and modelled via CATIA
2. Selection of appropriate connectors or robots:
Connectivity across the panels or transmission systems are not always the same. Depending
on the environment at which its functioning and gradeability of material these factors are
considered to select the appropriate ones.
3. Understanding mechanism behind worm and worm shafts:
The powertrain for the entire HR mechanism is dealt by worm and worm shafts mechanism.
With real-life problems given to us, we were asked to deal with determining torque, rpm,
variation in torque, material selection, mating parameters etc.
This mechanism is also referred as speed reducer. Where the driven shaft is rotated at low
speed compare to the driver worm gear. The entire gears rotate not just by mating of teeth’s,
the worm mechanism function solely because of sliding motion. Thereby there is slight

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increase in wear and heat generation. But since our robot functions at very slow speed, the
parameter of heat generation within tooth profiles can be neglected.
The specialty of this mechanism is that the gears rotate only with help of worm shaft
rotation and the vice versa rotation is not achievable.
Fig.7 Prototype for verifying worm and worm shaft mechanism
4. Considering manufacturing issues for low cost:
Almost all the mechanical components like housing of gears, support structures, seals were
to be customized individually for HSCR. Designing these parts for robot were done without
compromising the manufacturing ease. Since the pats were too small, at most care was
taken when deciding simple support structures. Complex hose shelter, excessive chamfers,
uneven material thickness, machinability etc. factors were considered.
5. Calculation of Power and torque transmission:
The HSCR mobility in pipe and cutting tool rotation were received from a single DC motor.
Following factors were considered in selecting the DC motor:
• High torque with low rpm
• Motor size
• Durability
• High load capacity
6. Understanding tolerance, surface finish, screw selections:
Not all the parts of the robots require high surface finish because, excessive surface finish
builds up additional cost in manufacturing thereby increasing overall cost of the robot.
Cylindrical support for the worm shafts axis must align with worm shaft and tool shat in

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horizontal axis in exact position. If this is not taken care, eccentricity occurs in the shafts
axis resulting in unwarranted vibrations and wobbling. These parameters were noted down
and cross verified after every iteration in CATIA during assembly process and alterations
we made accordingly.
Fig 8. (left image) Grub screw with Black Oxide coating and ordinary grub screw with
no additional coating (right image)
Screw selection were one of the prominent in considering the temporary joint structures.
We had selected screw bases on the factors like space availability, assembly space, screws
capacity to hold load. At the casings of worm gears with wheels, grub screws were selected
and to justify the section the reasons were due to compact insertion in the hole, no
unnecessarily protrusion even after complete mating and with simple need of assembly tool
like single M3 and M4 hexa head Allen key.
The screws selected were primarily chosen with ‘Black Oxide’ coating because the
environment at which the robot operates is completely exposed to sluggish/moisture
contents. This compound prevents rust from forming on the steel and also gives the part
some resistance to mild abrasion. This process doesn't actually oxidize the metal.
7. Structural Analysis for stresses and deformation:
Once the aforesaid parameters were determined and applied to models and assemblies, we
tested with notorious forces along the boundary conditions and its performance were
notified.
Using COMSOL Multiphysics we initially proceeded with structural analysis at the thin
cylindrical columns. Since the robot consisted of 3 axis wheels around the periphery of this
structure, moments and compressive forces were also generated in it. We ensured that it
remains well below the desired requirements.

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Fig.9 Screenshot of analysis results in COMSOL Multiphysics
8. Pipe dimensions and its terminologies:
While we enumerate and plan the design for robots wheels it was evident to know the
internal diameter of the PVC pipes. These data provided on how to choose the wheels
dimensions flexibly with varying dimensions of PVC pipe. A simple alpha numerical of
PVC pipe provides details like inner diameter, outer diameter, resemblance of shape, etc.
9. Drafting via CATIA:
Ensuring the modelled parts are stored for future references and forwarding to the
manufacturers imbibing drafting tool is must. I happen to receive several opportunities to
interact with manufacturers of our robot’s components, where I must provide them sturdy
information of the part in dimensioning on draft sheets via first angle projections only. I
happen to familiarize with drafting tools like cut section, providing annotation, placing
templates within drafting and sharing the files in .dwg or .pdf formats.
Fig 8. Sample drafted sheet used for design data storage

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10. Additive manufacturing (3D printing) for prototypes:
One of the best opportunities received to me was interacting with 3D printers and hands on
experience with its function. Considering the level of our necessity and budget allotted, I
happen to provide them the correct specifications and model of 3D printer required.
Fig 9. 3D printed gears from Ender Reality printer
Even assembling the 3D printers was a tricky task i.e., the levelling of the stage/platform
bed of printer has to be ensured at the most using hand spirit leveler, if it is not aligned
parallel to the base plane the entire additive parts being printed would shift to incline for
every layer being deposited, which would lead to part failure eventually.
11. Imbibing slicing software – IdeaMaker:
Just purchasing the 3D printer, the work flow doesn’t end here, I had to learn a slicing
software i.e., a computer tool used for discretizing the modelled part into numerous fine
layered structures for additive process.
From the company’s instruction I happen to IdeaMaker tool, where the model to be printed
must be taken at most care on selecting the parameters like:
• Platform structure like brim, skirt and raft.
• Type/size of support structures/ filler percentage
• Feed rate
• Bed temperature
• Filler rate, speed of filler inflow rate, ooze at idle.
• Nozzle temperature, etc.
Numerous parameters along with the above taken must be carefully given as input for every
orientation to material size too. For example, ABS (Acrylonitrile Butadiene Styrene) must
have nozzle and bed temperature varying from 220 °C to 250 °C and 100°C to 110 °C
respectively. Similarly all parameters and values vary for PETG and PLA fillers too.

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Fig 10. Illustration of one of the prototypes being prepared in IdeaMaker for
manufacturing
12. Troubleshooting the issues while 3D printing:
At times the input data might not match the actual needed parameter or there could be
unwarranted trouble while the 3D print is printing on. Issues like filler material being
snapped up from feeder nozzle, platform inclination, axis mobility belts sagging away,
malfunctioning of thermistor, building up of material lumps, etc. must be noted and
rectified immediately. If not rectifed immediately then the entire time invested in that 3D
print goes to trash.
Fig An issue from bed level sensor led to accumulation of additive material in improper
manner.

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RELEVANCE TO THE ACADEMICS
With relevance to academic approach I happen to acquire and develop new and improvise
my existing skills. With regards to it, I have enumerated few:
• Traditionally in academic wise, we are provided with questions containing several
parameters with that we figure out the solutions. But in real scenario it was not the
case; instead I had to find out the torque and rpm available the end of wheel to
transit the motion of robot inside the pipe.
• With just the motors input torque and rpm from the shaft, using the gear ratio,
coefficient of friction inside blocked pipe, power-torque relations, etc I calculated
the output torque and rpm at the wheel. I t must be noted that the enough torque is
available at the wheels and tools tip/ tools periphery to remove the accumulated
sluggish around the inner diameter of pipe.
• In the on go of internship program, an additional task was assigned to calculate the
amount of thrust to be generated to lift 21 Kg of mass (Fig. 5) and attain altitude of
120 feet from ground of payload lifting drone. Hence, I researched on the motors
and propellers design/factors on how it affects the lift.
• Using COMSOL multi-physics software, static structural analysis was imbibed by
me, which gave different perspective rather than ABAQUS or ANSYS APDL
software.
• Presenting our ideas to others i.e., non-mechanical teams enhanced my skill of
simplifying terminologies and explaining our concept in lay man terms.
• Using FDM 3D printers gave me insight of how the additive manufacturing differs
from subtractive manufacturing like factors in building, part generation etc.

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CONCLUSIONS
In my venture with Drona Automation as an intern Design Engineer, the opportunity received
were overwhelmed. From getting used to CATIA for modelling/simulation, COMSOL for
analysis, for rendering the products, improve in presentation techniques, idea generation, etc.,
all these skills were acquired and developed over time during the venture with Drona
Automation.
Along with the design of automatic sewage robotics, I received certain opportunity to involve
in building up of agricultural drone that was needed to fertilizing the Areca Nut trees and
provide solution for human satirizer robot during the pandemic situation for non-contact
purposes.
In the upcoming future Drona Automations will provide 3 premium products of MSPCR-1,
VSPCR- I and HSPCR-I needed for automated sewage cleaning in our country, which will
definitely pave way new era of sewage cleaning.
With a team consisting of enthusiastic youngsters and dedicated directors, the probability of
successful launch and completion of the project is indeed very high in upcoming days.

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REFERENCES
[1] Piotr Kardasz1, Jacek Doskocz1, Mateusz Hejduk, Paweł Wiejkut and Hubert Zarzycki
- “Drones and Possibilities of Their Use”, Journal of Civil & Environmental Engineering,
17 September 2016.
[2] Mr. Saurabh S. Satpute, Mr. Vitthal R. Darole, Mr.Pravin M.Khaderao ,Mr..Pankaj B.
Hiralkarl – “Automatic Sewage Cleaning System” , International Journal of Advance
Engineering and Research Development, A National Conference On Spectrum Of
Opportunities In Science & Engineering Technology Volume 5,April-2018
[3] "COMSOL Modeling Software". COMSOL.com. Comsol, Inc. Retrieved 20 November
2015.
[4]"CAD software history CAD CAM computer aided design 1980 to 1985". cadazz.com.
Retrieved 2020-07-23.
[5] Ganesh U L, Vinod V Rampur – “Semi-Automatic Drain For Sewage Water Treatment
Of Floating Materials” , International Journal of Research in Engineering and Technology,
13 December 2016.