ESA research strives to overcome feedback delays in Analog-1 tests

ESA says the next test is scheduled for this summer on the volcanic slopes of Mount Etna, to simulate a more realistic environment.

Research at the European Space Agency (ESA) continues to explore the possibility of astronauts working from orbiting spacecraft while controlling robots to perform studies on the ground.

A new study published yesterday (April 20) in the journal ScienceRobotics details how ESA’s Analog-1 experiments overcame a two-way signal delay between the robot rover on Earth and its controller on the ISS.

The Analog-1 mission was the culmination of 11 experiments conducted over a decade by ESA as part of the METERON (Multi-Purpose End-To-End Robotic Operation Network) project to test ways to interact with robots from a distance.

The biggest success came in 2019 when astronaut Luca Parmitano got direct haptic feedback from a ground robot with an advanced gripper with the equivalent mobility of a human hand.

“This is the first time an astronaut in space has been able to control a robotic system on the ground in such an immersive and intuitive way,” said Aaron Pereira of the German Aerospace Center DLR.

Pereira said the control interface incorporates force feedback so the astronaut can feel what the rover is feeling.

“What this does is help compensate for any bandwidth limitations, poor lighting or signal delay to give a real sense of immersion – meaning the astronaut feels like they’re there. at the scene,” added Pereira.

Added “passivity” to force feedback

The research team said they needed to overcome issues with the delay in force feedback received by the operator, which meant the operator could continue to move the robot even if it got stuck on a rock.

“This could lead to the robot getting out of sync with its controller, potentially vibrating like crazy, possibly even damaging itself,” Pereira said.

To avoid this, the research team used a concept called “passivity”, looking at the amount of energy the operator puts in and ensuring the robot never gives out more energy than it needs. receives it.

“So, for example, when the robot arm moves and suddenly hits a rock, it would take extra energy to move, which the astronaut did not command, so we reduce the command energy immediately to slow down the arm,” Pereira said.

“Then, after the 850 microsecond delay, when the astronaut feels the rock, he can then choose to add the extra energy to push it.”

The research team said the biggest limitation of their experiments to date is that indoor lunar test environments lack realism. To improve on this, the next phase of Analog-1 testing will take place this summer on the volcanic slopes of Mount Etna in Italy.

In 2020, China’s Chang’e 5 mission became the first to bring back rocks from the moon since 1976, making it the third country to achieve the feat. Rocks and lunar samples were collected by a lander using a robotic arm and dropped into an ascending craft.

While numerous missions have taken robots to the Moon and other planetary surfaces over the past five decades, and more are on the way, the dexterity and control seen in the Analog-1 test could help astronauts to undertake more complex missions in the future.

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