Robots are more electrical, which means they are battery dependent. Batteries have a low energy density, and Robots need a lot of them or frequently recharge to feature a better run time.
A team of researchers at the University of Southern California have created the Robeetle, an 88-milligram four-legged robot powered by liquid methanol.
We have seen a tiny robot that mimics cheetah for faster crawling. But this one is different! This fantastic micro-bot has earned its developer, Pérez-Arancibia, the Guinness World Record for the lightest crawling Robot. It is the most miniature crawling Robot ever developed and can carry objects up to 2.6 times its weight. It uniquely uses methanol for movement, including traversing through different surfaces and climbing slopes.
So how does the microbot work without a battery? Let’s find out. But before that, let’s see the design that makes the entire mechanism possible.
The innovative design of the RoBeetle
RoBeetle is a quadruped Bot with two front legs attached to a single transmission and fixed rear legs. The Robot’s front legs move together, creating a forward-up and then backward-down motion. The transmission is connected to a leaf spring that allows the Robot to stand when it’s not moving.
RoBeetle has horns that keep the spring in place and carry objects. The Bot’s body is a fuel tank with a fuel inlet to fill it up with methanol.
The Robotic Beetle is unique because its artificial muscles imitate the real ones, contracting and relaxing. It consists of actuators made up of nickel-titanium, shape-memory alloy(SMA) wire covered in platinum powder. One end of the SMA wire is attached to the leaf spring, and the other end to an anchor on the Robot’s back.
The platinum coating reacts with methanol vapor to produce heat which shortens the wires in the Robot’s legs that re-extend on cooling down, making Robeetle move forward. Now, that is smart!
The actuators of the microbot also work as its sensors. It is made possible by its little vent connected to the transmission. Its motion also regulates the flow of fuel through its body.
Let’s look at the complete process to understand better.
RoBeetle walks for hours without a battery
RoBeetle’s body can hold 95 milligrams of methanol. A full tank takes around 155 minutes to evaporate completely, which means the Robot can walk for approximately two hours and about 7.068 meters without any need for a battery.
Initially, the Robot has a full fuel tank and a cold SMA wire. It creates tension on the leaf spring, pulling the legs backward and making the Robot stand upright. The transmission also pulls open the vent, allowing methanol vapor to escape from its body and into the air.
Here is where the platinum coating comes into play. It facilitates the combustion reaction of the methanol with oxygen present in the air.
This generates heat, and the SMA wire temperature rises from 50 to 100 ºC in just a second. As a result, the wire gets longer, and the Robot moves forward about 1.2 mm. Meanwhile, the transmission closes the vent, cutting off the methanol supply. The reaction stops, and the wire cools down. It gets shorter and creates tension on the leaf spring again.
This entire cycle is responsible for the movement of Robeetle. As of now, the Robot can acquire a top speed of 0.76 millimeters per second.
One interesting fact about the microbot is that it can travel faster if a gentle breeze flows over its body. How? This happens because the air moving across the SMA wire cools down the system faster and removes any residual methanol around the vents, completing the entire cycle more quickly.
Future of the RoBeetle
This is only the start of Minuscule RoBeetle’s journey, and the researchers are hopeful that this invention can be a significant change in the microbot industry. However, specific issues need to be mentioned.
Presently, the tiny Robotic Beetle can only move forward, and it cannot steer. The speed of the Bot cannot be controlled, and it keeps moving till it runs out of fuel. There are a lot of scopes for improvement, and the researchers are already working on it.
“By arranging multiple fiber-like thin artificial muscles in hierarchical configurations similar to those observed in sarcomere-based animal muscle,” its developers are hopeful of making it even more insect-like.
Nature-inspired robots are increasingly being used in commercial industries. If the current issues are solved, RoBeetle can change how microbots work today and can find its use in complex surgeries, artificial pollination, aerial locomotion, and a lot more.