China's Shenzhou-19 crew aboard the orbiting Tiangong space station recently completed the in-orbit test of a pipeline inspection robot, laying a solid technical foundation for future pipeline inspections on the space station.

The astronauts constructed a simulated pipeline in orbit, which included straight pipes, curved pipes and conical pipes of various diameters. Within this simulated pipeline, they conducted tests on the robot's mobility, its extraction from its contracted state and its extraction after fine-tuning its status, according to the China Manned Space Agency (CMSA).

During the test, the robot demonstrated stable and reliable movement through various types of pipelines, validating its autonomous mobility technology designed to suit multiple complex pipeline structures. Additionally, the robot could be easily extracted from complex pipelines even after a power outage, confirming the safety of its passive compliant mechanism.

As the first in-orbit test of a special-purpose robot conducted on China's space station, it showcased the robot's autonomous adaptability and safety in complex pipeline environments, accumulating valuable experience for future practical applications of robots in space station pipelines, the CMSA said.

The CMSA noted that a pipeline inspection robot faces numerous challenges within pipelines. For instance, it must adapt to the complex structures inside the space station's pipelines and complete autonomous movements.

It also needs to ensure its own safety -- including maintaining appropriate contact force with pipeline walls, adapting to changes in pipeline diameter and avoiding becoming stuck in the pipeline in unexpected situations.

To overcome these challenges, researchers developed a biomimetic variable stiffness design for this pipeline inspection robot.

Inspired by the tube feet of echinoderms such as starfish, sea urchins and sea cucumbers, which retract into the body when at rest and extend outward during movement, the researchers designed a combined active and passive leg-scissor mechanism for the robot.

The passive mechanism enables the robot's legs to swiftly adjust their length in response to changes in pipe diameter, ensuring adaptability to varying pipe sizes.

Meanwhile, the active mechanism dynamically regulates the pressure between the robot's feet and the pipe wall, guaranteeing reliable contact and providing sufficient propulsion for the robot to move forward.

The robot's intelligent "brain" calculates its posture and position using its full-body sensors and generates a motion strategy. Under the premise of ensuring pipeline safety, it adjusts the positions, speeds and force outputs of all joints to enable smooth movement within the space station's pipelines.

During the test, ground personnel monitored the robot's position, current, contact force and other status data in real-time through ground support software, synchronously observing the robot's movement. This allowed them to assist astronauts in completing in-orbit operations.

Also, by analyzing the acquired data, ground personnel assessed the test results, providing a basis for subsequent experiments.