Scientists seeking to understand the behavior of animals in their natural environment have to go to great lengths to blend in with the locals. If the tools being used to observe these creatures are disruptive or otherwise unnatural, it will alter their behavior in any number of ways. And that, of course, renders the observations all but useless.
Unfortunately, most of the technologies, like drones or other robots, that are used for these purposes stick out like a sore thumb. Consider the submersible drones used for underwater exploration, for instance. The motors are noisy, and they eject jets of water that churn up sediment and disrupt everything in their vicinity. That is no way to make friends.
An overview of the hardware design (đź“·: A. Mathew et al.)
A team led by researchers at Khalifa University in Abu Dhabi recognized that if you want to fit in with the crowd, you have to act the part. So rather than using traditional methods of propulsion in their submersible drone, they borrowed some ideas from bacteria. In particular, they gave their drone artificial flagella, which are the whip-like appendages that allow single-celled organisms to silently zip around aqueous environments.
To us, the researchers’ soft-bodied underwater drone called ZodiAq may look like something straight out of a nightmare, but the design has a purpose. Its dodecahedral shell was chosen for both symmetry and functional redundancy. Each of the 12 pentagonal faces of this geometric structure houses a soft flagella module powered by a DC motor. These arms mimic the motion of natural bacterial flagella by rotating slowly with high torque, causing them to twist into a helical shape and push the drone forward without aggressive thrust or noisy propellers.
Contained within the shell of ZodiAq is a Raspberry Pi 4 Model B computer that manages both control and communication. It is connected to a suite of onboard sensors that enable the robot to make intelligent decisions in real-time. These include a camera for visual data, an inertial measurement unit to track orientation and motion, a depth sensor, and a temperature and humidity sensor for internal diagnostics. All of these feed into an intelligent control system that was developed with the help of a digital twin simulation that allows the team to test and tweak behaviors before real-world deployment.
Paging H. G. Wells… (đź“·: A. Mathew et al.)
Communication in underwater environments is notoriously difficult due to the limitations of radio frequency transmission in water. To solve this, ZodiAq is equipped with an acoustic modem for underwater data exchange, allowing it to remotely send updates and receive commands even while submerged.
ZodiAq has already been tested in various real-world scenarios. It has proven itself to be capable of maintaining functionality even if one or more of its flagella modules fail, due to the built-in redundancy. It can even perform crawling gaits along the seabed and navigate tight spaces like coral reefs, all while remaining unobtrusive to the marine life around it.
When we get stumped by an engineering problem, the best course of action often turns out to be to look for a solution that already exists in nature. By taking this approach, the ZodiAq team has given scientists a better way to observe wildlife in its natural state.