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Robotic Space Worms (with Dr. Riddhi Das)

Dean chats with Dr. Riddhi Das, a soft robotics researcher developing earthworm-inspired robots for planetary exploration. They discuss how these wriggly-yet-rigid innovations, with autonomous drive and locomotive capabilities, will navigate challenging terrains and their potential applications in space exploration.


Which types of robots do you envision as valuable assets for Earth's challenging environments? Share your thoughts with us by emailing or joining the conversation on social media using #lookinguppod

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Looking Up is transcribed using a combination of AI speech recognition and human editors. It may contain errors. Please check the corresponding audio before quoting in print.

Dean Regas: When you hear the word robot, what do you think of it?

[Educational Program Clip]: You may think of a robot as a mechanical creature that walks around.

Dean Regas: For me personally, it's lots of, you know, metal cubes, flailing arms. Not really coordinated like you knock it over, but then it would like be super dependable always there for you Kind of human like now imagine a robot designed specifically to collect samples on another planet What would it be made of what would its function be?

What if I told you that robots like this are in development right now, and they look nothing like what you're imagining in fact They're designed to look like worms

From the studios of Cincinnati Public Radio. I'm your host Dean Regas, and this is Looking Up.

The show that takes you deep into the cosmos or just to the telescope in your backyard to learn more about what makes this amazing universe of ours so great.

Our guest this week is Dr. Riddhi Das, postdoctoral researcher at the University of Freiburg, in Griezgau, Germany. An engineer developing an earthworm like robot for use around the solar system.

Well, this is going to be exciting talking about different types of robots. And I, you know, I was kind of joking a little bit about robots. I actually don't picture humanoid looking robots that much. I don't know if it's. Maybe because they kind of creep me out a little bit, like some of those new ones that can like throw baseballs and dance, I don't know, but I think really the, the ones that strike me as like real robots are the cars on Mars, like the rovers, you know, they have the names like Spirit and Opportunity and Perseverance and Curiosity.

This is what you think of when you think robots also, they have these six wheels and somebody on Earth is driving them. There's some drawbacks to these things. First off, you're going to be driving a car on Mars. There's a big lag time. You have to say, okay, I want the car to drive forward 10 feet and turn right.

So you have to send that. And then at the speed of light, that takes somewhere on the order of 8 to 25 minutes for the signal to get there. If you're going to Mars, especially. So you say, go forward 10 feet, turn right and send. So that goes to the robot. It does it, and then you don't know if it did it. For 30, 40 minutes.

And so the idea is, can we make something that's a little more autonomous? Sometimes a robot can't wait for mission control. It has to make decisions on its own. This ability is called autonomy. And the rovers are in a sense, able to do this. They have some technology in them that allow them to adjust for the train, adjust for things that are in the way, and that they can do this in a semi autonomous way.

So there's some ideas. How can you make. Other kinds of rovers and other kinds of robotic crafts. The latest mission was a pretty good one where they sent that rover that had the helicopter, the drone called ingenuity, but you can't fly it in real time. You have to program it ahead of time. And so it could make these kinds of leaps and fly around different parts of Mars.

But there's other ones that are on the table that could be really interesting. We're going to be learning about one that's crawls a little closer to the ground, but there's also ones that are like balls that can like shoot off, have this piston that comes out and shoots off. And then it can roll down the hill a little bit and go to somewhere to investigate things.

So it doesn't have to be exactly like six wheels and driven and this kind of thing. It could be flying, it could be bouncing, it could be rolling. And with the technology that we have now, the things don't have to be gigantic. You think, well, so why do we have to make them so big? Let's make them smaller and less like humans, please.

Cause they're too creepy when they're like humans. Although I don't know, we're going to be talking about worm shaped robots, but I don't know if that's better or worse, but I'm excited to talk about this with Dr. Das. Thanks for doing this this morning.

Dr. Riddhi Das: No, no, thanks a lot for inviting me. It's really a pleasure.

So, I'm Riddhidas. Dr. Riddhidas, exactly. Yeah. I'm a postdoctoral researcher. Yeah, University of Freiburg.

Dean Regas: What made your team choose earthworms for inspiration?

Dr. Riddhi Das: Because it's one of the most common natural burrows that you get to see. Like, if you go to your backyard or your garden and you use a shovel, you generally see some of these little creatures wriggling around.

If you see, like earthworms, their biology and their anatomy is very well studied. So you can exactly get all the literature and all the information about the biology right at your hands. And along with that, like if you consider the other contemporary burrowers, most of them generally use like their claws, nails, or other appendages in order to create the burrows and then move inside.

Whereas the earthworms being entirely soft, they're quite unique because In spite of being soft, they're able to create this kind of tunnels and they can move inside these tunnels and make their way through it. So that's why we took inspiration from Earthworms because also our lab focuses on soft robots.

So this is the exact soft animal which we were looking for as an inspiration.

Dean Regas: What's the, this robot made of, you know, it's not like hard metals, it's not rigid. Yeah. What's, what's the composition of these?

Dr. Riddhi Das: Presently, the robot has like five actuator modules, and then the tip, there's one tip module.

If you look into the biology of the earthworms, the earthworms generally have a totally segmented body, entirely soft. And each of the segments, considering them like cylindrical segments, they basically have a constant volume of fluid. Which is called the technically it's called the coelomic fluid.

And this fluid cannot pass on to the external segments because there are, like, muscles which prevent it from passing. And on the external side, in the circular way, there are, like, two sets of muscles. Basically, the longitudinal and circular muscles. And these muscles, when they act alternately on these segments, generally, these cylindrical segments change in shape.

So, basically, they either elongate, like, longitudinally elongate, or they become bulged out, like, radially expand. So, basically when this alters in shape to the entire body, it forms wave patterns. And in this way, it actually moves. So this thing we also, like, translated in our robot actuator module, where with positive pressure and negative pressure, we were able to generate, like elongation and also radial expansion.

Now, this elongation and radial expansion is pretty important because this elongation actually helps the robot or the earthworm to move and the radial expansion actually helps the system to anchor to the surroundings.

[Educational Program Clip]: Some nervous impulses coordinate the movement of the body and

extension and retraction of the bristles.

The bristles enable the earthworm to hold on to the slippery sides of the burrow and withdraw into it.

Dr. Riddhi Das: So we replicated that in our robot. And considering about the materials, I would say it was totally made with flexible materials like elastomeric materials and which made the robot flexible to all the surroundings.

The main idea about developing a soft robot is that it has to be flexible because it can adapt to external surroundings and it can move over uneven terrain.

Dean Regas: Well, and that seems like a huge plus because, you know, we think of the normal rovers as, you know, they get stuck quite a bit sometimes. And so there's pluses to having different ways of locomotion.

You mentioned kind of digging and tunneling. How is that important for these space missions to like get below the surface?

Dr. Riddhi Das: One of the important applications for developing a borrowing robot also from a space perspective is planetary excavation. But that's one of the main target application. So the idea is like that we envision that in the future there would be like planetary rovers, which would carry this kind of borrowing robots.

Now, presently, I think with the present state of the art, it is possible to develop like a probe inside the inside the planetary regolith and collect some samples from there.

[Educational Program Clip]: Digging on the earth and digging on the moon are two incredibly different tasks. The moon is a vast desert of dust, several inches thick.

This moon dust is called Lunar Regolith, because it's technically not soil. Soil is defined by having organic content.

Dr. Riddhi Das: But in the future with this kind of burrowing robot, what we can do is, like, we can deploy them, and they will be able to autonomously move around and burrow, and can collect samples, like soil samples, and then it can return back for further analysis to the rover.

Dean Regas: And then, of course, these are going to be on different planets or different worlds. You can't really, like, drive them in real time. They can be kind of semi autonomous. Say, okay, we want you to go here and do this task and it can get there kind of thing.

Dr. Riddhi Das: Right now, the newest version is actually able to also bend.

So, that's why it can change its direction and the tip we have also included force sensors in the tip. So, basically, it's able to understand the penetration force while it's moving. So, the idea is, like, in the future, that the robot itself is able to understand the amount of resistance it has to face in the front and change its locomotory pattern.

So, either it moves its head from time to time in order to reduce the resistance in front. And if it sees that the resistance is not enough, it directly starts locomoting and it follows a particular gate pattern, depending on the medium it is moving in.

Dean Regas: Well, it seems like a whole different field of robotics in a lot of ways.

What kind of challenges are you facing in the design process?

Dr. Riddhi Das: In my case, one of the challenges I mostly faced while developing the robot was generating this radial force and also longitudinal force. So if I look into most of the state of the art earthworm robots, what we see is like they are toggled between two different configurations where they elongate and then go back to their original shape.

But in case of my robot, Basically, it toggles between three configurations, where it starts from a neutral state, it with positive pressure it basically elongates each of the module, and with negative pressure it radially expands and anchors to the surface. So this change in configuration, when it travels through the entire body in a systematic way, it generally constitutes a wave.

Now, these wave patterns, when it passes through the entire body, it interacts with the surroundings and creates some friction. And because of this friction, it's possible to move over the environment. Since we are able to generate this kind of radial forces, we solved one of the crucial elements in the design problem, and we were able to move in different medium with different kinds of gate patterns.

From a personal perspective, I would say like while developing this robot because it in my PhD I started with soft robotics, which was totally new for me before this. The robotics I was doing was mostly traditional robots. So with rigid motors and stuff. So here I learned a lot about soft actuator technologies and soft fabrication methods.

So that was also quite challenging for me in the beginning.

Dean Regas: When it's fascinating to find inspiration from actual biology, you know, how earthworms actually move on Riddhi Das. What was it like to kind of incorporate the natural world, the biology of an animal into a robotic entity?

Dr. Riddhi Das: Yeah, it's, it's really something like, I mean, I used to design robots from a different point of view, but then understanding by inspiration took me quite some time.

It's not exactly biomimicry because in biomimicry, what we. Think about is what we see in the nature. We try to replicate that exactly in the system, but it's not going to happen because nature has also perfected it with years of evolution. So we can't like exactly replicated that. But what we try to incorporate in our robot is what we see in the nature and what could be useful and then try to transform some of the design principles from it into our robot.

Dean Regas: Well, how does somebody get started in the field of robotics? How'd you get started working in this field?

Dr. Riddhi Das: My background was in mechanical engineering and the thing that interested me mostly in the aspect of robotics was robot design. I would say from an inspiration point of view, I was pretty much interested with like transformers, Gundam and all this kind of stuff.

So that interested me quite a lot. And then. Coming into robot design, I understood that how each of the components face different kinds of forces and challenges while moving inside a real robust environment. So these are the aspects from a mechanical point of view, but obviously if you want to get started in robotics, I'd say like first also understand a bit about the electronics.

Like there are a lot of like resources outside because you can get started with an Arduino and can do some basic sensor stuff. And obviously there's also the part about coding the robot. So basically there's a lot of open source libraries available. So these, I would say is like a starter pack for getting into robotics.

And then it's mostly like your own area or your own interest, which you would want to like focus on.

Dean Regas: Well, so what's next for these wormy robots? Are they scheduled to visit any other planet anytime soon?

Dr. Riddhi Das: I would say it's a pretty early stage in the research, but yeah, obviously a lot of work is being done and what we are trying to explore is trying to make them much more autonomous.

And also another important thing that we have to do in order to make the robots like real world deployable, I would say is So that we can remove soil particles through the robot, because in order to move inside a granular medium or a very robust soil environment, it has to also remove soil from through the robot, which also the real earth worm does.

So this is also like one of the things that we want to implement in our robot. And also along with that, there's the thing about making it autonomous so that it can sense this environment and can act on it.

Dean Regas: Is Mars the most likely candidate for something like this?

Dr. Riddhi Das: I mean, it can be any planet, so obviously, if we make a robust robot able to move a different medium here, then we can try it anywhere.

Dean Regas: And big question, have you ever introduced real earthworms to the earthworm robot? No, not yet. There's a pretty big size difference, I would imagine. What's, what's the typical size of the the robot?

Dr. Riddhi Das: The, the robot is about around 50 millimeter in dia, so it's bigger than the real earthworms.

But we obviously had thoughts about reducing its size, but once we reduce in size, there are also other problems because The actuation could be difficult because it has a lot of components inside in the sense there is like a bellow shaped component which actually helps in this kind of configuration change.

And also there's this fluid inside and the external surrounding medium. So there are several components but reducing them to a much lesser size would be difficult but I won't say possible but yeah, maybe in the later on we can achieve that.

Dean Regas: Well, this has been really fascinating and I can't wait to see where these robots end up and how your research goes.

Best of luck with it. Thanks so much for talking with me today.

Dr. Riddhi Das: Thanks a lot. Thanks for having me.

Dean Regas: Well, I think that robots are going to be part of our lives here on Earth and in space. It is kind of fun to think about the different ways we can go about exploring the universe, because we're going out into a place, into an environment that is not very good for us.

Every place In space, all the moons, all the planets, you know, we would die in five seconds if we were on them. Yeah. Well, if you didn't have a space suit and all that kind of stuff, the robots can withstand a lot of these things and having them in different configurations in different ways are gonna be really fascinating.

So I want you to think a little bit about this. What kind of robots would you see as being helpful here on? Earth because we have a lot of applications that extend not just to space travel, but there's places with challenging environments here on earth to think about what might be good for that. And let us know if you have any questions, comments, or suggestions for future topics, you can always email us at looking up at wvxu.

org. Looking up with Dean Regas is a production of Cincinnati public radio. Ella Rowen is our show producer and studio robot. Yep. Yep. She's moving. She's doing the robot right now. Marshall Verbsky assists with the audio production and earthworm collection. Digging. Quit digging. We got enough. We got enough.

Our theme song is Possible Light by Ziv Moran. I'm Dean Regas and keep looking up.