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Using a Raspberry Pi to help sensor-carrying drones ‘talk’ to eachother

19 April 2018

New hardware and software that coordinate sensor-carrying drones may be able to assist in measuring electronic signals and mapping areas in three dimensions.

A sensor-carrying drone is ready to fly during testing at an athletic field. (Credit: by Jeff Fitlow/Rice U.)

Application programming interfaces (APIs) will allow users to customise the drones to meet specific sensing requirements.

“The system is designed to be application-agnostic in the sense that you can use our APIs and libraries to build any kind of autonomous solution that you want,” says Kevin Lin, an engineering student at Rice University. “Based on what we’ve seen at the Olympics and other presentational shows, you could totally use our software to build something like that.”

Getting off the ground

The research team, all electrical and computer engineering majors, developed the platform as a generic tool that can carry out a wide range of sensing tasks on its own.

“It’s easy for them to communicate in a peer-to-peer way, but all the underlying complexities of how the communication works are abstracted out to the programmer,” Lin says. “We provide really nice APIs to make it fairly painless for a client to get them to talk to each other.”

The team spent the school year writing more than 10,000 lines of code and testing one drone and then multiple ones.

Each drone is equipped with a Wi-Fi dongle that allows them to form a mesh network that enables communication across long distances without requiring a central access point. They’re also equipped to avoid obstacles and track altitude through on-board LIDAR (light detection and ranging) instruments. Each drone uses a Raspberry Pi as its central processor, and most can lift between 1 and 2 kilograms.

All those capabilities helped the team test several applications, including its primary goal of sensing signal strength from a stationary Wi-Fi hot spot in the middle of a university athletic field.

“That was useful because it showcased two drones coordinating and sharing their data,” Lin says. “They just looped through the field and took measurements at all the points we programmed. We fed that into an algorithm that localised the hot spot.”

One experiment involved LIDAR, which uses a pulsed laser to locate surrounding objects. “We mounted a spinning LIDAR on one of the drones,” says Andrew Brooks. “That gives us a planar cross section of the environment.”

Raising and lowering the drone - and thus, the horizontal plane - allows the team to capture slices of the immediate environment and build a 3D map. During testing in the university’s engineering quad, a LIDAR-equipped drone detected and mapped walls, arches, and even trees.

Sometimes, the drones crashed, but the nature of kit-based drones is that the parts are easy to acquire and the fliers have become easier to repair.

“It’s a lot cheaper to take the individual components and put them together,” Lin says. “Our project is supposed to run on relatively cheap hardware, so our drones are mostly kits but with some modifications here and there.”

“Unless you plan to buy a whole new drone every time you crash one, it’s important to know how to take them apart and put them back together,” Brooks says.

Helping with disaster relief

Living in Houston over the past year inspired one application for future investigation.

“Hurricane Harvey came shortly after we started working on this project, so there were thoughts of attaching gas sensors to our drones,” says Emilio Del Vecchio. “When some of the refineries started leaking gas, there were human health hazards. So our idea was people could possibly use these drones to measure the magnitude of a leak and determine where people shouldn’t be allowed to go.

“The application-agnostic nature of it makes it really easy to staple on whatever sensor you like and write some really simple mission code,” he says. “Nobody sees the next Hurricane Harvey coming more than a few weeks out. It’s important to have the barrier [to] entry for constructing something like this be really low.”

“We truly want to support as many different kinds of sensors as we can imagine,” Lin says.

Source: Rice University

The original article can be found on the Futurity website.


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