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#437723 Minuscule RoBeetle Turns Liquid Methanol ...

Posted on November 26, 2020 by Android

It’s no secret that one of the most significant constraints on robots is power. Most robots need lots of it, and it has to come from somewhere, with that somewhere usually being a battery because there simply aren’t many other good options. Batteries, however, are famous for having poor energy density, and the smaller your robot is, the more of a problem this becomes. And the issue with batteries goes beyond the battery itself, but also carries over into all the other components that it takes to turn the stored energy into useful work, which again is a particular problem for small-scale robots.

In a paper published this week in Science Robotics, researchers from the University of Southern California, in Los Angeles, demonstrate RoBeetle, an 88-milligram four legged robot that runs entirely on methanol, a power-dense liquid fuel. Without any electronics at all, it uses an exceptionally clever bit of mechanical autonomy to convert methanol vapor directly into forward motion, one millimeter-long step at a time.

It’s not entirely clear from the video how the robot actually works, so let’s go through how it’s put together, and then look at the actuation cycle.

Image: Science Robotics

RoBeetle (A) uses a methanol-based actuation mechanism (B). The robot’s body (C) includes the fuel tank subassembly (D), a tank lid, transmission, and sliding shutter (E), bottom side of the sliding shutter (F), nickel-titanium-platinum composite wire and leaf spring (G), and front legs and hind legs with bioinspired backward-oriented claws (H).

The body of RoBeetle is a boxy fuel tank that you can fill with methanol by poking a syringe through a fuel inlet hole. It’s a quadruped, more or less, with fixed hind legs and two front legs attached to a single transmission that moves them both at once in a sort of rocking forward and up followed by backward and down motion. The transmission is hooked up to a leaf spring that’s tensioned to always pull the legs backward, such that when the robot isn’t being actuated, the spring and transmission keep its front legs more or less vertical and allow the robot to stand. Those horns are primarily there to hold the leaf spring in place, but they’ve got little hooks that can carry stuff, too.

The actuator itself is a nickel-titanium (NiTi) shape-memory alloy (SMA), which is just a wire that gets longer when it heats up and then shrinks back down when it cools. SMAs are fairly common and used for all kinds of things, but what makes this particular SMA a little different is that it’s been messily coated with platinum. The “messily” part is important for a reason that we’ll get to in just a second.

The way that the sliding vent is attached to the transmission is the really clever bit about this robot, because it means that the motion of the wire itself is used to modulate the flow of fuel through a purely mechanical system. Essentially, it’s an actuator and a sensor at the same time.

One end of the SMA wire is attached to the middle of the leaf spring, while the other end runs above the back of the robot where it’s stapled to an anchor block on the robot’s rear end. With the SMA wire hooked up but not actuated (i.e., cold rather than warm), it’s short enough that the leaf spring gets pulled back, rocking the legs forward and up. The last component is embedded in the robot’s back, right along the spine and directly underneath the SMA actuator. It’s a sliding vent attached to the transmission, so that the vent is open when the SMA wire is cold and the leaf spring is pulled back, and closed when the SMA wire is warm and the leaf spring is relaxed. The way that the sliding vent is attached to the transmission is the really clever bit about this robot, because it means that the motion of the wire itself is used to modulate the flow of fuel through a purely mechanical system. Essentially, it’s an actuator and a sensor at the same time.

The actuation cycle that causes the robot to walk begins with a full fuel tank and a cold SMA wire. There’s tension on the leaf spring, pulling the transmission back and rocking the legs forward and upward. The transmission also pulls the sliding vent into the open position, allowing methanol vapor to escape up out of the fuel tank and into the air, where it wafts past the SMA wire that runs directly above the vent.

The platinum facilitates a reaction of the methanol (CH3OH) with oxygen in the air (combustion, although not the dramatic flaming and explosive kind) to generate a couple of water molecules and some carbon dioxide plus a bunch of heat, and this is where the messy platinum coating is important, because messy means lots of surface area for the platinum to interact with as much methanol as possible. In just a second or two the temperature of the SMA wire skyrockets from 50 to 100 ºC and it expands, allowing the leaf spring about 0.1 mm of slack. As the leaf spring relaxes, the transmission moves the legs backwards and downwards, and the robot pulls itself forward about 1.2 mm. At the same time, the transmission is closing off the sliding vent, cutting off the supply of methanol vapor. Without the vapor reacting with the platinum and generating heat, in about a second and a half, the SMA wire cools down. As it does, it shrinks, pulling on the leaf spring and starting the cycle over again. Top speed is 0.76 mm/s (0.05 body-lengths per second).

An interesting environmental effect is that the speed of the robot can be enhanced by a gentle breeze. This is because air moving over the SMA wire cools it down a bit faster while also blowing away any residual methanol from around the vents, shutting down the reaction more completely. RoBeetle can carry more than its own body weight in fuel, and it takes approximately 155 minutes for a full tank of methanol to completely evaporate. It’s worth noting that despite the very high energy density of methanol, this is actually a stupendously inefficient way of powering a robot, with an estimated end-to-end efficiency of just 0.48 percent. Not 48 percent, mind you, but 0.48 percent, while in general, powering SMAs with electricity is much more efficient.

However, you have to look at the entire system that would be necessary to deliver that electricity, and for a robot as small as RoBeetle, the researchers say that it’s basically impossible. The lightest commercially available battery and power supply that would deliver enough juice to heat up an SMA actuator weighs about 800 mg, nearly 10 times the total weight of RoBeetle itself. From that perspective, RoBeetle’s efficiency is actually pretty good.

Image: A. Kitterman/Science Robotics; adapted from R.L.T./MIT

Comparison of various untethered microrobots and bioinspired soft robots that use different power and actuation strategies.

There are some other downsides to RoBeetle we should mention—it can only move forwards, not backwards, and it can’t steer. Its speed isn’t adjustable, and once it starts walking, it’ll walk until it either breaks or runs out of fuel. The researchers have some ideas about the speed, at least, pointing out that increasing the speed of fuel delivery by using pressurized liquid fuels like butane or propane would increase the actuator output frequency. And the frequency, amplitude, and efficiency of the SMAs themselves can be massively increased “by arranging multiple fiber-like thin artificial muscles in hierarchical configurations similar to those observed in sarcomere-based animal muscle,” making RoBeetle even more beetle-like.

As for sensing, RoBeetle’s 230-mg payload is enough to carry passive sensors, but getting those sensors to usefully interact with the robot itself to enable any kind of autonomy remains a challenge. Mechanically intelligence is certainly possible, though, and we can imagine RoBeetle adopting some of the same sorts of systems that have been proposed for the clockwork rover that JPL wants to use for Venus exploration. The researchers also mention how RoBeetle could potentially serve as a model for microbots capable of aerial locomotion, which is something we’d very much like to see.

“An 88-milligram insect-scale autonomous crawling robot driven by a catalytic artificial muscle,” by Xiufeng Yang, Longlong Chang, and Néstor O. Pérez-Arancibia from University of Southern California, in Los Angeles, was published in Science Robotics. Continue reading →

Posted in Human Robots

#437716 Robotic Tank Is Designed to Crawl ...

Posted on November 26, 2020 by Android

Let’s talk about bowels! Most of us have them, most of us use them a lot, and like anything that gets used a lot, they eventually need to get checked out to help make sure that everything will keep working the way it should for as long as you need it to. Generally, this means a colonoscopy, and while there are other ways of investigating what’s going on in your gut, a camera on a flexible tube is still “the gold-standard method of diagnosis and intervention,” according to some robotics researchers who want to change that up a bit.

The University of Colorado’s Advanced Medical Technologies Lab has been working on a tank robot called Endoculus that’s able to actively drive itself through your intestines, rather than being shoved. The good news is that it’s very small, and the bad news is that it’s probably not as small as you’d like it to be.

The reason why a robot like Endoculus is necessary (or at least a good idea) is that trying to stuff a semi-rigid endoscopy tube into the semi-floppy tube that is your intestine doesn’t always go smoothly. Sometimes, the tip of the endoscopy tube can get stuck, and as more tube is fed in, it causes the intestine to distend, which best case is painful and worst case can cause serious internal injuries. One way of solving this is with swallowable camera pills, but those don’t help you with tasks like taking tissue samples. A self-propelled system like Endoculus could reduce risk while also making the procedure faster and cheaper.

Image: Advanced Medical Technologies Lab/University of Colorado

The researchers say that while the width of Endoculus is larger than a traditional endoscope, the device would require “minimal distention during use” and would “not cause pain or harm to the patient.” Future versions of the robot, they add, will “yield a smaller footprint.”

Endoculus gets around with four sets of treads, angled to provide better traction against the curved walls of your gut. The treads are micropillared, or covered with small nubs, which helps them deal with all your “slippery colon mucosa.” Designing the robot was particularly tricky because of the severe constraints on the overall size of the device, which is just 3 centimeters wide and 2.3 cm high. In order to cram the two motors required for full control, they had to be arranged parallel to the treads, resulting in a fairly complex system of 3D-printed worm gears. And to make the robot actually useful, it includes a camera, LED lights, tubes for injecting air and water, and a tool port that can accommodate endoscopy instruments like forceps and snares to retrieve tissue samples.

So far, Endoculus has spent some time inside of a live pig, although it wasn’t able to get that far since pig intestines are smaller than human intestines, and because apparently the pig intestine is spiraled somehow. The pig (and the robot) both came out fine. A (presumably different) pig then provided some intestine that was expanded to human-intestine size, inside of which Endoculus did much better, and was able to zip along at up to 40 millimeters per second without causing any damage. Personally, I’m not sure I’d want a robot to explore my intestine at a speed much higher than that.

The next step with Endoculus is to add some autonomy, which means figuring out how to do localization and mapping using the robot’s onboard camera and IMU. And then of course someone has to be the first human to experience Endoculus directly, which I’d totally volunteer for except the research team is in Colorado and I’m not. Sorry!

“Novel Optimization-Based Design and Surgical Evaluation of a Treaded Robotic Capsule Colonoscope,” by Gregory A. Formosa, J. Micah Prendergast, Steven A. Edmundowicz, and Mark E. Rentschler, from the University of Colorado, was presented at ICRA 2020.

< Back to IEEE Journal Watch Continue reading →

Posted in Human Robots

#437697 These Underwater Drones Use Water ...

Posted on November 25, 2020 by Android

Yi Chao likes to describe himself as an “armchair oceanographer” because he got incredibly seasick the one time he spent a week aboard a ship. So it’s maybe not surprising that the former NASA scientist has a vision for promoting remote study of the ocean on a grand scale by enabling underwater drones to recharge on the go using his company’s energy-harvesting technology.

Many of the robotic gliders and floating sensor stations currently monitoring the world’s oceans are effectively treated as disposable devices because the research community has a limited number of both ships and funding to retrieve drones after they’ve accomplished their mission of beaming data back home. That’s not only a waste of money, but may also contribute to a growing assortment of abandoned lithium-ion batteries polluting the ocean with their leaking toxic materials—a decidedly unsustainable approach to studying the secrets of the underwater world.

“Our goal is to deploy our energy harvesting system to use renewable energy to power those robots,” says Chao, president and CEO of the startup Seatrec. “We're going to save one battery at a time, so hopefully we're going to not to dispose more toxic batteries in the ocean.”

Chao’s California-based startup claims that its SL1 Thermal Energy Harvesting System can already help save researchers money equivalent to an order of magnitude reduction in the cost of using robotic probes for oceanographic data collection. The startup is working on adapting its system to work with autonomous underwater gliders. And it has partnered with defense giant Northrop Grumman to develop an underwater recharging station for oceangoing drones that incorporates Northrop Grumman’s self-insulating electrical connector capable of operating while the powered electrical contacts are submerged.

Seatrec’s energy-harvesting system works by taking advantage of how certain substances transition from solid-to-liquid phase and liquid-to-gas phase when they heat up. The company’s technology harnesses the pressure changes that result from such phase changes in order to generate electricity.

Image: Seatrec

To make the phase changes happen, Seatrec’s solution taps the temperature differences between warmer water at the ocean surface and colder water at the ocean depths. Even a relatively simple robotic probe can generate additional electricity by changing its buoyancy to either float at the surface or sink down into the colder depths.

By attaching an external energy-harvesting module, Seatrec has already begun transforming robotic probes into assets that can be recharged and reused more affordably than sending out a ship each time to retrieve the probes. This renewable energy approach could keep such drones going almost indefinitely barring electrical or mechanical failures. “We just attach the backpack to the robots, we give them a cable providing power, and they go into the ocean,” Chao explains.

The early buyers of Seatrec’s products are primarily academic researchers who use underwater drones to collect oceanographic data. But the startup has also attracted military and government interest. It has already received small business innovation research contracts from both the U.S. Office of Naval Research and National Oceanic and Atmospheric Administration (NOAA).

Seatrec has also won two $10,000 prizes under the Powering the Blue Economy: Ocean Observing Prize administered by the U.S. Department of Energy and NOAA. The prizes awarded during the DISCOVER Competition phase back in March 2020 included one prize split with Northrop Grumman for the joint Mission Unlimited UUV Station concept. The startup and defense giant are currently looking for a robotics company to partner with for the DEVELOP Competition phase of the Ocean Observing Prize that will offer a total of $3 million in prizes.

In the long run, Seatrec hopes its energy-harvesting technology can support commercial ventures such as the aquaculture industry that operates vast underwater farms. The technology could also support underwater drones carrying out seabed surveys that pave the way for deep sea mining ventures, although those are not without controversy because of their projected environmental impacts.

Among all the possible applications Chao seems especially enthusiastic about the prospect of Seatrec’s renewable power technology enabling underwater drones and floaters to collect oceanographic data for much longer periods of time. He spent the better part of two decades working at the NASA Jet Propulsion Laboratory in Pasadena, Calif., where he helped develop a satellite designed for monitoring the Earth’s oceans. But he and the JPL engineering team that developed Seatrec’s core technology believe that swarms of underwater drones can provide a continuous monitoring network to truly begin understanding the oceans in depth.

The COVID-19 pandemic has slowed production and delivery of Seatrec’s products somewhat given local shutdowns and supply chain disruptions. Still, the startup has been able to continue operating in part because it’s considered to be a defense contractor that is operating an essential manufacturing facility. Seatrec’s engineers and other staff members are working in shifts to practice social distancing.

“Rather than building one or two for the government, we want to scale up to build thousands, hundreds of thousands, hopefully millions, so we can improve our understanding and provide that data to the community,” Chao says. Continue reading →

Posted in Human Robots

#437689 GITAI Sending Autonomous Robot to Space ...

Posted on November 24, 2020 by Android

We’ve been keeping a close watch on GITAI since early last year—what caught our interest initially is the history of the company, which includes a bunch of folks who started in the JSK Lab at the University of Tokyo, won the DARPA Robotics Challenge Trials as SCHAFT, got swallowed by Google, narrowly avoided being swallowed by SoftBank, and are now designing robots that can work in space.

The GITAI YouTube channel has kept us more to less up to date on their progress so far, and GITAI has recently announced the next step in this effort: The deployment of one of their robots on board the International Space Station in 2021.

Photo: GITAI

GITAI’s S1 is a task-specific 8-degrees-of-freedom arm with an integrated sensing and computing system and 1-meter reach.

GITAI has been working on a variety of robots for space operations, the most sophisticated of which is a humanoid torso called G1, which is controlled through an immersive telepresence system. What will be launching into space next year is a more task-specific system called the S1, which is an 8-degrees-of-freedom arm with an integrated sensing and computing system that can be wall-mounted and has a 1-meter reach.

The S1 will be living on board a commercially funded, pressurized airlock-extension module called Bishop, developed by NanoRacks. Mounted on the inside of the Bishop module, the S1 will have access to a task board and a small assembly area, where it will demonstrate common crew intra-vehicular activity, or IVA—tasks like flipping switches, turning knobs, and managing cables. It’ll also do some in-space assembly, or ISA, attaching panels to create a solar array.

Here’s a demonstration of some task board activities, conducted on Earth in a mockup of Bishop:

GITAI says that “all operations conducted by the S1 GITAI robotic arm will be autonomous, followed by some teleoperations from Nanoracks’ in-house mission control.” This is interesting, because from what we’ve seen until now, GITAI has had a heavy emphasis on telepresence, with a human in the loop to get stuff done. As GITAI’s founder and CEO Sho Nakanose commented to us a year ago, “Telepresence robots have far better performance and can be made practical much quicker than autonomous robots, so first we are working on making telepresence robots practical.”

So what’s changed? “GITAI has been concentrating on teleoperations to demonstrate the dexterity of our robot, but now it’s time to show our capabilities to do the same this time with autonomy,” Nakanose told us last week. “In an environment with minimum communication latency, it would be preferable to operate a robot more with teleoperations to enhance the capability of the robot, since with the current technology level of AI, what a robot can do autonomously is very limited. However, in an environment where the latency becomes noticeable, it would become more efficient to have a mixture of autonomy and teleoperations depending on the application. Eventually, in an ideal world, a robot will operate almost fully autonomously with minimum human cognizance.”

“In an environment where the latency becomes noticeable, it would become more efficient to have a mixture of autonomy and teleoperations depending on the application. Eventually, in an ideal world, a robot will operate almost fully autonomously with minimum human cognizance.”
—Sho Nakanose, GITAI founder and CEO

Nakanose says that this mission will help GITAI to “acquire the skills, know-how, and experience necessary to prepare a robot to be ISS compatible, prov[ing] the maturity of our technology in the microgravity environment.” Success would mean conducting both IVA and ISA experiments as planned (autonomous and teleop for IVA, fully autonomous for ISA), which would be pretty awesome, but we’re told that GITAI has already received a research and development order for space robots from a private space company, and Nakanose expects that “by the mid-2020s, we will be able to show GITAI's robots working in space on an actual mission.”

NanoRacks is schedule to launch the Bishop module on SpaceX CRS-21 in November. The S1 will be launched separately in 2021, and a NASA astronaut will install the robot and then leave it alone to let it start demonstrating how work in space can be made both safer and cheaper once the humans have gotten out of the way. Continue reading →

Posted in Human Robots

#437683 iRobot Remembers That Robots Are ...

Posted on November 24, 2020 by Android

iRobot has released several new robots over the last few years, including the i7 and s9 vacuums. Both of these models are very fancy and very capable, packed with innovative and useful features that we’ve been impressed by. They’re both also quite expensive—with dirt docks included, you’re looking at US $800 for the i7+, and a whopping $1,100 for the s9+. You can knock a couple hundred bucks off of those prices if you don’t want the docks, but still, these vacuums are absolutely luxury items.

If you just want something that’ll do some vacuuming so that you don’t have to, iRobot has recently announced a new Roomba option. The Roomba i3 is iRobot’s new low to midrange vacuum, starting at $400. It’s not nearly as smart as the i7 or the s9, but it can navigate (sort of) and make maps (sort of) and do some basic smart home integration. If that sounds like all you need, the i3 could be the robot vacuum for you.

iRobot calls the i3 “stylish,” and it does look pretty neat with that fabric top. Underneath, you get dual rubber primary brushes plus a side brush. There’s limited compatibility with the iRobot Home app and IFTTT, along with Alexa and Google Home. The i3 is also compatible with iRobot’s Clean Base, but that’ll cost you an extra $200, and iRobot refers to this bundle as the i3+.

The reason that the i3 only offers limited compatibility with iRobot’s app is that the i3 is missing the top-mounted camera that you’ll find in more expensive models. Instead, it relies on a downward-looking optical sensor to help it navigate, and it builds up a map as it’s cleaning by keeping track of when it bumps into obstacles and paying attention to internal sensors like a gyro and wheel odometers. The i3 can localize directly on its charging station or Clean Base (which have beacons on them that the robot can see if it’s close enough), which allows it to resume cleaning after emptying it’s bin or recharging. You’ll get a map of the area that the i3 has cleaned once it’s finished, but that map won’t persist between cleaning sessions, meaning that you can’t do things like set keep-out zones or identify specific rooms for the robot to clean. Many of the more useful features that iRobot’s app offers are based on persistent maps, and this is probably the biggest gap in functionality between the i3 and its more expensive siblings.

According to iRobot senior global product manager Sarah Wang, the kind of augmented dead-reckoning-based mapping that the i3 uses actually works really well: “Based on our internal and external testing, the performance is equivalent with our products that have cameras, like the Roomba 960,” she says. To get this level of performance, though, you do have to be careful, Wang adds. “If you kidnap i3, then it will be very confused, because it doesn’t have a reference to know where it is.” “Kidnapping” is a term that’s used often in robotics to refer to a situation in which an autonomous robot gets moved to an unmapped location, and in the context of a home robot, the best example of this is if you decide that you want your robot to vacuum a different room instead, so you pick it up and move it there.

iRobot used to make this easy by giving all of its robots carrying handles, but not anymore, because getting moved around makes things really difficult for any robot trying to keep track of where it is. While robots like the i7 can recover using their cameras to look for unique features that they recognize, the only permanent, unique landmark that the i3 can for sure identify is the beacon on its dock. What this means is that when it comes to the i3, even more than other Roomba models, the best strategy, is to just “let it do its thing,” says iRobot senior principal system engineer Landon Unninayar.

Photo: iRobot

The Roomba i3 is iRobot’s new low to midrange vacuum, starting at $400.

If you’re looking to spend a bit less than the $400 starting price of the i3, there are other options to be aware of as well. The Roomba 614, for example, does a totally decent job and costs $250. It’s scheduling isn’t very clever, it doesn’t make maps, and it won’t empty itself, but it will absolutely help keep your floors clean as long as you don’t mind being a little bit more hands-on. (And there’s also Neato’s D4, which offers basic persistent maps—and lasers!—for $330.)

The other thing to consider if you’re trying to decide between the i3 and a more expensive Roomba is that without the camera, the i3 likely won’t be able to take advantage of nearly as many of the future improvements that iRobot has said it’s working on. Spending more money on a robot with additional sensors isn’t just buying what it can do now, but also investing in what it may be able to do later on, with its more sophisticated localization and ability to recognize objects. iRobot has promised major app updates every six months, and our guess is that most of the cool new stuff is going to show in the i7 and s9. So, if your top priority is just cleaner floors, the i3 is a solid choice. But if you want a part of what iRobot is working on next, the i3 might end up holding you back. Continue reading →

Posted in Human Robots