Self-flying drones and autonomous taxis that can operate safely in fog may seem futuristic, but new research at Sandia National Laboratories’ fog facility is bringing the future closer.
Fog can make water, air and land travel dangerous when it becomes difficult for people and sensors to detect objects. Researchers at the Sandia Fog Facility are meeting this challenge through new optical research in computer imaging and by partnering with NASA researchers working on Advanced Air Mobility, Teledyne FLIR and others to test sensors in a custom fog that can be repeatedly measured and produced on demand.
“Improving optical sensors to better perceive and identify objects through fog is important to protect human life, prevent property damage, and enable new technologies and capabilities,” said Jeremy Wright, Engineer optical.
Built in 2014, Sandia’s fog chamber is 180 feet long, 10 feet high and 10 feet wide. The chamber is covered with a plastic sheet to trap the fog.
When the team begins a test, 64 nozzles whistle as they spray a custom mixture of water and salt. As the spray spreads, moisture builds up and a thick fog forms. Soon an observer inside will no longer be able to see the walls, ceiling or entrance through the spray and people and objects a few feet away will be obscured or completely hidden.
Sandia researchers carefully measure the properties of fog over time to understand how it forms and changes. By adjusting the environmental parameters, researchers can alter the properties of fog to better match natural fog.
“Our team can fully measure and characterize the fog that we produce in the facility, and we can repeatedly generate a similar fog on different days,” said Andres Sanchez, chemical engineer. “It is important to have consistent and measurable conditions when we test the performance of sensors in fog.”
Enabling safe all-weather operations for autonomous vehicles, airplanes and drones
Researchers from NASA’s Ames Research Center recently visited Sandia to perform a series of experiments to test how commercially available sensors perceive obstacles in fog. The Revolutionary Aviation Mobility group is part of NASA’s Transformational Tools and Technologies project.
“We have tested perception technologies that could enter autonomous aerial vehicles,” said Nick Cramer, NASA’s chief engineer for this project. “We want to make sure that these vehicles are able to operate safely in our airspace. This technology will replace a pilot’s eyes, and we need to be able to do that in all types of weather.”
The team set up a stationary drone in the chamber as a target, then tested various sensors to see how well they could perceive the drone in the fog.
“The Sandia National Laboratories fog chamber is extremely important for this test,” Cramer said. “It allows us to really tune the parameters and look at variations over long distances. We can reproduce long distances and various types of fog that are relevant to the aerospace environment.”
Cramer said one of the challenges with auto-theft technology is that there would be a lot of small vehicles flying nearby.
“We have to be able to detect and avoid these small vehicles,” Cramer said. “The results of these tests will allow us to determine what are the current gaps in perception technology for moving to autonomous vehicles. “
Fog installation helps prove the technology
Teledyne FLIR tested its own infrared cameras at Sandia’s fog facility to determine how well they detect and classify pedestrians and other objects. Chris Posch, technical director, automotive, for Teledyne FLIR, said the cameras could be used to both improve the safety of today’s vehicles with advanced features of driver assistance systems such as braking. automatic emergency and autonomous vehicles of the future.
“Fog tests are very difficult to do in nature because they are so ephemeral and there are many inherent differences typically seen in the size of water droplets, consistency and repeatability of fog or fog,” said Posch. “As the Sandia fog facility can repeatedly create fog with different water content and size, the facility played a vital role in collecting test data in a scientifically thorough manner. “
Sandia and Teledyne FLIR performed several performance tests with vehicle security sensors, including visible cameras, long wave infrared cameras, medium wave infrared cameras, short wave infrared cameras and lidar.
Posch said the results showed that Teledyne FLIR’s long-wave infrared cameras can accurately detect and classify pedestrians and other objects in most fogs, where visible cameras are put to the test.
New research to detect, locate and image objects through fog
A team of Sandia researchers recently published an article in Optical Express describing the current results of a three-year project to use computer imaging and the science behind how light travels and scatters in fog to create algorithms that allow sensors to detect, locate and image objects in the fog.
“Current methods of seeing through fog and with scattered light are expensive and may be limited,” said Brian Bentz, electrical engineer and project manager. “We are using what we know about how light travels and scatters in fog to improve detection and situational awareness capabilities.”
Bentz said the team modeled how light travels through fog to an object and a detector (usually a pixel in a camera), then inverted that model to estimate where the light was coming from and the characteristics of the object. By changing the model, this approach can be used with visible or thermal light.
Bentz says the team used the model to detect, locate and characterize objects in the fog and will be working on object imagery during the final year of the project. The team used the Sandia fog facility for experimental validations.
Along with this research, the Sandia team created two benchtop fog chambers to support a project of University Alliance Partner West Lafayette, Purdue University, based in Indiana.
Sandia studies and characterizes the fog generated by her new benchtop fog chamber, while Purdue uses her twin system to perform experiments.
Purdue professor Kevin Webb is leading research to develop imaging technology based on how light interferes with itself as it diffuses and using those effects to detect objects.
The Sandia team recently presented their work to SPIE and CLEO.
Bad weather data could help autonomous vehicles see
Brian Z. Bentz et al, Light transport with low angular dependence in fog, Optical Express (2021). DOI: 10.1364 / OE.422172
Brian Z. Bentz et al, Detection and location of hidden objects in fog, Virtual, Augmented and Mixed (XR) Reality Technology for Multi-Domain Operations II (2021). DOI: 10.1117 / 12.2587995
Quote: Testing sensors in the fog to make future transport safer (2021, November 18) retrieved November 18, 2021 from https://techxplore.com/news/2021-11-sensors-fog-future-safer.html
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