Honeywell Aerospace engineers have developed a compact radar system to help urban air mobility (UAM) vehicles rapidly progress to autonomous flight.
The RDR-84K system, designed by a team from Honeywell’s Urban Air Mobility and Unmanned Aerial Systems unit in Phoenix, is currently being tested on a drone.
The project team has spent most of 2021 building the algorithm and beginning to flight test the unit under real conditions. The company’s goal is to build a system useful for air taxi and UAM operations.
“We are interested in how…the plane [is] going to eliminate conflicts between a drone and a manned vehicle,” Lawrence Surace, senior scientist for advanced technology strategy at Honeywell Aerospace, told FlightGlobal on April 12. “In December, we successfully detected an intruding drone and autonomously bypassed it.”
The unit, housed in a 3D-printed frame the size of a large paperback, can detect targets the size of a King Air aircraft at around 1.7nm (3km). According to engineers, it can detect a helicopter at around 3,300 feet and identify a smaller drone at 1,000 feet.
Honeywell is a leader in building radars for large commercial aircraft, so the project was not started in a vacuum. What’s unique is the RDR-84K’s small size and powerful capabilities.
“We shrunk it down” so it could be used on a new generation of aircraft, says Surace. “This radar is specially designed for detect and avoid, but it also has other features, such as ground mapping, weather detection, ground obstacle detection [and] air-to-air and air-to-ground detection of multiple targets.
“Air to air [detection] is a very challenging environment because the radar needs a lot of information about its own position to be able to take control of the drone and steer it in the right direction,” says Surace. “It’s a very complex algorithm that we’re implementing.”
The unit weighs approximately 1.4 kg (3 lbs). Engineers are working on a next iteration that will weigh half that. They expect it to be ready for testing this quarter.
Honeywell aims to have the technology integrated into delivery drones by 2025.
“We can network up to seven radars on a vehicle, for 360 degree coverage. Many of our customers request one that points outward and one that is angled at 45 degrees so that when the aircraft comes in for a landing they can take advantage of our terrain mapping capability.
Radar, Surace says, is more reliable at detecting and avoiding than lidar-based systems. Lidar, which stands for Light Detection and Ranging, uses a laser to make 3D measurements of objects.
“With radar, you don’t have light problems. You can see at night. You don’t get smog, fog, any of those issues that you would have with a lidar light based system. Radar is sort of the all-weather, all-capability solution,” he adds.
With the system proven in a basic frontal crash scenario, the next stage of flight testing will involve more complex flight scenarios.
“We would like to make several drones in several different scenarios. [The unit] can detect up to 30 targets in its field of view and track 30 targets at the same time. So we would like to send a number of vehicles there,” he says. “Now is the time to really test it, stretch your legs and see what it can do.”
According to the engineers, there are many applications for this type of radar, including search and rescue missions at sea or the mapping of dangerous weather fronts and microbursts.
For UAM vehicles, the system would be useful for critical phases of flight such as take-off and landing.
Due to the physics of radar capabilities, it would be impractical and prohibitively expensive to equip small UAM vehicles with large, heavy radar systems capable of detecting and avoiding conflicts throughout flights. Therefore, Honeywell engineers envision the RDR-84K system as part of a larger ecosystem that also relies on ground-based systems.
“Strategic deconfliction will happen on the ground, from a control station, much like air traffic control does today,” Surace said. “This radar would be useful for applications from zero to 400 feet, takeoff or landing, for example.” The system could detect a rogue drone or an obstacle when the vehicle is going up or down.
The radar is not designed to distinguish whether other objects are, for example, birds or aircraft. It can also detect objects on the ground like buildings and trees.
“The algorithm says, ‘Okay, there’s something out there, and I know it’s moving right at me at this speed, and I know I’m moving at this speed.’ So he starts the calculation that says, ‘I have to turn that fast in that direction, at that time, to miss that target.’ And those calculations continue continuously,” Surace explains. over there that’s big enough to be seen, he’ll avoid it.”
Honeywell said it was working with air taxi developers Lilium and Vertical Aerospace on avionics and flight control systems for those companies’ UAM concepts. It is also developing flight control and satellite communication and sensor systems for a heavy cargo drone developed by Pipistrel, recently acquired by Textron Aviation.