(ORDO NEWS) — If man’s best friend is a dog, then in the future, astronauts’ closest friends may well be rovers.
A research team from ESA, the German Aerospace Center DLR, European academia and industry has developed a methodology to allow astronauts in orbit to control surface-survey rovers, resulting in a ground rover controlled from the International Space Station. An article published this week in the journal Science Robotics details the findings.
“This is the first time an astronaut in space has been able to control a robotic system on the ground in such an exciting, intuitive way,” comments Aaron Pereira of DLR.
“Our 6-DOF control interface includes force feedback so that the astronaut can feel everything the rover feels, down to the weight and density of the rocks it touches. This helps to compensate for any bandwidth limitations, poor lighting, or signal delay, creating a real sense of immersion, that is, the astronaut feels as if he is present at the scene.
Robotics engineer Thomas Krueger, who heads ESA’s Human-Robot Interaction Lab, adds: “Robots can be given limited autonomy in known, structured environments, but systems that perform research tasks such as collecting samples in unknown, unstructured environments need some control. However, direct control is not possible due to the problem of signal delay, the transmission time of which is limited by the speed of light.
“We are therefore working on the concept that humans can safely and comfortably orbit the Moon, Mars or other planetary bodies, yet be close enough to directly control rovers on the surface – combining human strengths such as flexibility and improvisation. , with a reliable, nimble robot in place to carry out its commands with precision.”
A team from ESA’s HRI Laboratory and DLR’s Center for Robotics and Mechatronics worked on a series of progressively more complex tests, first on Earth, then in orbit.
“Ultimately, we needed to conduct feasibility studies from space because past research has shown that weightlessness can degrade human performance in strength and motion tasks,” adds Thomas. “This and other unique environmental factors meant that simulations on Earth would not be enough.”
The culmination of their efforts was the first part of the Analog-1 experiment, conducted at the end of 2019. Astronaut Luca Parmitano, aboard the ISS, operated the gripper-equipped ESA Interact rover in a hangar in Valkenburg, the Netherlands, to examine rocks and collect samples. The two-hour space-to-earth communication test was successful, overcoming a two-way signal delay of more than 0 on average.
“Despite the fact that the ISS is in orbit only 400 km above the earth, its signals are transmitted to Earth via geostationary telecommunications satellites, and then to Europe from Texas via a transatlantic cable,” explains Aaron.
“Our team at DLR had to develop a control algorithm that could function stably despite this time delay. Since there is a delay in the force feedback received by the operator, he can continue moving the robot further even after it hits a stone. This can cause the robot to become out of sync with its controller, potentially causing vibration, possibly even damaging the robot itself.
To prevent this from happening, we use the concept of “passivity”. “So, for example, when a robotic arm moves and suddenly hits a rock, the movement will require additional energy that the astronaut did not command, so we immediately reduce the energy to slow down the arm. Then, after a delay of 850 microseconds, when the astronaut feels the rock, he may decide to add extra energy to push it.”
This method is very intuitive in practice and should work well for higher time delays as well.
Thomas concludes: “The main limitation of the work done so far is that our artificial lunar environment lacks realism. Therefore, this summer will be the second part of Analog-1 on the volcanic slopes of Mount Etna in Italy, as part of a larger international robot testing campaign. titled ARCHES
“Luca Parmitano will once again fly our Interact rover, this time in 1G mode – from Earth.”
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