Flying high with robotics research
The best way to track radio-tagged sturgeon as the fish travel up and down the Wolf River is from above.
With drones, we can fly more often than people going out in a real plane to accomplish the task. And we can get the kinds of information that are currently not available, like the average velocity of certain kinds of fish.
The closer the tracking equipment can come, the stronger the radio signal will be. But flying near the surface of the water can be dangerous in a human-piloted airplane.
It sounds like a job for a robot or, in this case, an aerial drone.
“With drones, we can fly more often than people going out in a real plane to accomplish the task,” says Tom Consi, assistant professor of freshwater sciences and engineering. “And we can get the kinds of information that are currently not available, like the average velocity of certain kinds of fish.”
Consi calls fish-tracking a “niche” application for the robot, but notes that there are broader uses. One is multispectral imaging, a method of remotely monitoring harmful algae blooms, like red tide, to determine how fast – and where – they spread.
But it was the sturgeon-tracking, a project of another scientist at UWM’s School of Freshwater Sciences, that provided the impetus for two engineering undergrads, Brady Moe and Kris Rockey, to build a drone.
Developing a drone is a multidimensional task that includes aerodynamics, control, electronics and software. Before they could stock it with sensing equipment, GPS and a radio receiver, Rockey had to customize a very large remote-control model airplane to carry the gear.
“There is a relatively heavy payload,” he says. “The average weight it can handle is around two pounds. But the radio we’re using adds five pounds and is about the size of a car battery.
“We are using an industry-standard fish telemetry radio because we want to be able to compare our work to something people can already do with this equipment,” adds Rockey, who is working on his second UWM bachelor’s degree to pursue his interest in robotics.
Using a basic remote, the pair sets up the controls to respond to certain plane functions, including programming flight patterns into the GPS. “Often, it’s a ‘lawn mower survey’ – a simple back and forth over a specific area,” says Rockey.
Moe is in charge of the computer programming necessary to autopilot the plane – and he also had to learn to fly it, which was a lot more difficult than he expected.
Programming the autopilot had to be worked out through trial and error. To measure signal strength over a large area, he used pre-existing software and modified it to follow and scan for radio signals.
He then had to create a topographical map by plotting the signals using a course consisting of five randomly placed points. When he steered the plane successfully over each point, the radio picked up the signal and coordinated it with the autopilot.
It’s a complex system with many parts and very little time to respond when something goes wrong. But, Moe says, the sense of accomplishment is great.
“I like writing code and then watching it do that specific work in the physical world,” he says.