Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.


I am a scientist and this is where I work: Sarita Ahlawat

Sarita Ahlawat preparing for a light show with 800 drones to celebrate the east African country Djibouti's 45th Independence Day in June 2022. Credit: Sonu Singh

Sarita Ahlawat talks about drone swarm technology and making drones to suit India's extreme weather conditions

When we speak of scientists, what comes to mind? Test tubes, petri dishes, boring white lab coats in a boring old lab? How about mountain tops or the depths of the ocean, astrophysics observatories or remote wildlife sanctuaries? In this series called “I am a scientist and this is where I work”, we introduce you to the lives of scientists who work in diverse and unique settings – far removed from the popular stereotypes. Over the next few episodes, we will shadow such scientists in their unconventional workplaces.

In this episode, we hear from Sarita Ahwalat, who with a team of engineering physicists at the Indian Institute of Technology Delhi, makes magic in the sky with drone swarms.

Host: Subhra Priyadarshini, production and script: Aroma Warsi, sound editing: Prince George.



Sarita Ahlawat talks about drone swarm technology and making drones to suit India's extreme weather conditions

(Lightly edited for readability)

Speakers: Sarita Ahlawat, Subhra Priyadarshini

00:01 Sponsor announcement: This episode is produced with support from DBT Wellcome Trust India Alliance.

00:24 Subhra Priyadarshini: During Republic Day's Beating the Retreat ceremony in January 2022, New Delhi's monuments and skies were a canvas for celebration. Rashtrapati Bhavan, the Indian president's official residence was lit up in the colours of the national flag. Then suddenly, a globe appeared overhead and rotated in there, mirroring the Earth's movements. Soon, this morphed into a map of India. All of this was made possible through engineering -- a nifty combination of aeronautical, electronics, electrical, mechanical and robotics engineering. What people saw was the work of a swarm of drones, adding colour, light and pride to the Republic Day festivities of India.

So what made this eco friendly technology possible? Who controlled these automated aerial vehicles with the utmost precision? On this episode of the Nature India podcast series called, "I am a scientist, and this is where I work", join me Subhra Priyadarshini as I make a beeline for Sarita Ahlawat and her lab at the Indian Institute of Technology in Delhi. That's where all the drone action takes place. We're going to learn all about how these little flying machines, sometimes no bigger than the palm of your hand, go from the lab to the skies in perfect synchrony.

02:11 Sarita Ahlawat: We are one of the few groups in the country who are working on drone swarm technology. When you have multiple drones operated by a single user, it's called a drone swarm. So now you can have very many applications of this technology. And it's very easy because a single person is operating. And we have developed a capability to connect more than 1000 drones.

02:34 Subhra Priyadarshini: The first drone was built in 1907, and was called a quadcopter, whose successful lift off was only two feet, but it paved the way for the start of an exciting industry. Drones hit the consumer market back in 2006, and have become quite popular. Today, of course, we’ve come a long way. Networking of drones, or 'swarming' as it is called in drone lingo, offers tremendous benefits to almost every sector of the economy. Agriculture, law enforcement, geospatial mapping, delivery, photography, marketing, and I could go on. Interestingly, drone technology forms a key part of many countries' defense and disaster management programmes as well. But first, back to Sarita, and her team at Botlab Dynamics. Her workplace quite literally buzzes with ideas and cutting edge technology.

03:35 Sarita Ahlawat: Very soon, you will hear a drone buzzing around me. So one constant noise that you hear in our lab is the drone, small drones flying. They're testing them, calibrating them, getting them ready for the flight. I have two teams in the lab. And so please don't mind the noise that is around me. One of the drones is now flying near me and what my colleagues here is doing is calibrating the system and qualifying it for the flight.

04:07 Subhra Priyadarshini: This is a day in Sarita's life for more than six years now. She has a PhD in microbiology but what interests her is developing smart and sensitive diagnostic tools and monitoring devices. After working a couple of years in the US she has returned to IIT Delhi. That's when she started to collaborate with Tanmay Bunkar and Anuj Kumar Barnwal, both engineering physicists from IIT Delhi.

04:33 Sarita Ahlawat: Together, the three of us realized that India as a country is doing very well when it comes to software solutions. But when it comes to hardware building, our ecosystem is really poor. We do not make state of the art microscopes or cell phones, computers, smartwatches. So this was a common point, or rather a pain point, that we had felt over the years.

05:00 Subhra Priyadarshini: Okay, so the goal was to develop a homegrown drone, made in India. So how else are the drones made in your lab different from other commercially available drones?

05:11 Sarita Ahlawat: These drones can be operated just by a single user. And each drone is fitted with a programmable LED light. And using drones, we can create very many interesting formations in the sky. These drones are very small, they will fit in your hand, and they are lightweight. I'll tell you a small story on what brought us to actually building things in India, in-house. So it was in 2019, we had built a swarm of 10 drones. And they were a very smart system, could scan a one kilometer square area. And we build this system, very smart fitted with camera, could go to 10 kilometres, identify an object and take some action. And we took these systems to Pokhran. And you know, Pokhran, in Rajastan, has very harsh conditions, not only in terms of temperature, but windy and dusty too. And it was something that we had never experienced before. Not only we, our drones had never experienced something like that. The drones were performing so well at IIT Delhi campus. But in Pokhran, their performance was reduced to 30%. And the drones were falling apart, and we were trying to fix them. So after coming back from Pokhran, we had this realisation that we had actually just assembled these drones, we were using flight controller, which is the brain of the drone manufactured in Europe. And in Europe, you never see such weather conditions. Most of the electronic components we had put together, so none of the components that time was made by us, but we knew how to put the components together and put our algorithms on it. So that was a realisation that if we want to make any solution, every component has to listen to us and has to work in Indian conditions. So literally against the advice of everybody, we left everything and we started focusing on designing from scratch.

07:23 Subhra Priyadarshini: That's an important realisation indeed. So let's learn more about what a drone light show entails. These drones are programmed to fly in 3D space to make identifiable visual forms such as maps, symbols, faces or messages. To do this, an animation is prepared based on the requirements, which entails days of calculation, testing, coding, and of course, teamwork. So how does the day's work go by? What happens in the lab before you can wow audiences with this display in the skies?

08:01 Sarita Ahlawat: Usually we have two teams in house. One is a hardware team that designs. Hardware has two components -- one is we design the casing of how the drone should look. We work on CAD models, and we do 3D printing. So if you come to our lab, you'll see several 3D printers are working and making the casing. And the other team works on designing the electronics. So our team of engineers and artists first imagine how it's going to be, an animation is created. And that animation is then coded on each drone, and then we test them on the ground. The third team would be the field testing team. So after the drones are ready, they are taken to the ground. And numerous health check ups are done on each drone to make sure that the drone doesn't cross a certain area. And that it's healthy to fly around people because what we do is watched live by people. So we have to be very sure that the security both of the drone and people is carefully thought about.

09:12 Subhra Priyadarshini: Right. Let's talk more about that. There is public concern that these devices might pose a security and privacy risk. Or if they fail, they could damage property and injure people. So I suppose when you're working with hundreds of 1000s of drones in a swarm rather than just one, that becomes a whole lot more complicated. How do you manage that?

09:37 Sarita Ahlawat: I mean, that is the most important question. We used to do test flights under net, the nets that we use for cricket practicing. So we actually made a temporary jugaad kind of solution that we would fly under these nets which were meant for cricket testing, cricket net is very small. So, of course, when you fly them 240 meters, something can go wrong. So we do not take chance. So what we have done as a security precaution, and it has taken us one year of coding, so we do something called geo fencing. So we create a fence on each drone will stay only in a defined area. So let's say I'm making a formation in Rashtrapati Bhavan -- I do not want my drone to cross and go meet the Prime Minister, because then I will have a lot of trouble. So what we did is, we created a geofence. And so if the drone's, let's say, some sensor has gone off, and now the drone is not listening to any of the commands that we have put in, once it crosses the geofence code, it will commit a suicide, it will fall as soon as it's time to cross the geofence. And I just want to say because, you know, we are all scientists, and we're talking science, you can never have 100% guarantee ans some drone might have this failure. We have seen that sometimes, but this geofencing has, kind of, saved us. So they have committed suicide, and we call it the kill switch. So they just switch off and they fall.

11:21 Subhra Priyadarshini: Incredible, who knew drones have to pass tests and die by suicide if they fail. These light shows and formations are certainly very awe inspiring, but clearly time consuming.

11:37 Sarita Ahlawat: We do some pre-flight tests. We take the final formation flight, and in that the drones go in batches. So now, the interesting point is that every drone precisely knows where it needs to be. And the accuracy that we have is around 10 centimeter. And that is how these interesting formations can be created. And after the landing we again, you know, put the batteries off and disconnect them from the battery, and then put them back on the racks. And then the drones are taken back to the lab. And then we look at their log files, how every drone performed.

12:19 Subhra Priyadarshini: What Sarita is describing in just a few minutes actually takes days and weeks of refining and fine tuning. Despite days of conceptualisation, testing and of course these hiccups that you've mentioned, I'd love to know what satisfies you most about this work. Would you want to share a happy moment or a career high point with us?

12:43 Sarita Ahlawat: Whenever we make something that flies, I mean, that is always the most exciting part. So I always remember when we flew four drones, just four drones, and they flew in absolute precision. That was back in 2021 January, it was just four drones. And they were only making a square and they were going about a numerous times making the square in the sky. Like small children, we were jumping and screaming and being very happy. So every time we cross a milestone, something works. It brings extreme happiness. We really enjoy those moments.

13:23 Subhra Priyadarshini: It's certainly cause for happiness when a scientific pursuit that demands such precision and untiring effort is successful. We're excited to see the new heights Sarita and her team will achieve through this technology.

If you liked what you heard, be sure to share this episode of the Nature India podcast with friends and colleagues and check out our archives for more in both English and Hindi. When we meet next, we'll wander the dense forests and venture into the world of insects and birds, the workplace of our next featured scientist in this series. Thanks for tuning in. I'm your host Subhra Priyadarshini and this is the Nature India podcast, your go to podcast for all things science in India.

14:31 Sponsor announcement: This episode was produced with support from DBT Wellcome Trust India Alliance.

Nature Careers


Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing


Quick links