Engineers have developed a simple strategy to help robots remain stable while repairing satellites in orbit by using a second robotic arm to counterbalance movements.
Researchers at the University of Cincinnati found that a robot performing maintenance tasks in space can reduce unwanted motion by moving a second arm to offset the forces created by the working arm.
The approach could help prevent both the robot and the satellite from spinning or drifting during delicate repairs.
Maintaining orientation in microgravity is one of the biggest challenges in satellite servicing. Even a small push or bump during repairs can send a spacecraft tumbling, making operations risky and difficult to control.
To solve the problem, graduate student James Talavage and Professor Ou Ma designed a system called Dual-Arm Zero Momentum. In simulations, one robotic arm performs the repair task while the other moves strategically to cancel out motion.
Balancing robots in orbit
The concept draws inspiration from everyday human behavior. Just as a person uses their free arm to stay balanced on ice or while riding a bull, the robot uses its second arm to stabilize itself.
“Think about standing on the slippery ice. If I ask you to grab something with one arm, I’m sure you’ll use the other arm to balance yourself.”
Professor Ou Ma said that making contact with satellites in space can be extremely difficult because even slight physical interactions can destabilize the spacecraft.
“Physical contact is always the most difficult and critical part. Physical interactions can cause damage and make the satellite unstable,” Ma said.
In their simulations, the second arm automatically adjusts its movement to counter yaw, pitch, or roll disturbances caused by the repair arm. This helps maintain the orientation of both the robot and the satellite during servicing tasks.
The research is part of ongoing work at Ma’s Intelligent Robotics and Autonomous Systems Laboratory, where scientists study technologies for in-space service, assembly, and manufacturing.
Fixing satellites safely
Satellite servicing is becoming more important as Earth’s orbit grows increasingly crowded. Thousands of satellites already operate in low Earth orbit, and more are being launched each year.
Damaged or defunct spacecraft also pose a growing problem. If collisions between satellites or debris increase, they could trigger a cascade of impacts known as the Kessler effect, potentially making some orbits unsafe for future missions.
“It is definitely something that will have an effect in my lifetime unless we can do something about it,” Talavage said.
Researchers say robotic servicing systems could help extend satellite lifetimes, repair damaged components, or remove debris from orbit.
“I think it’s a very practical solution with the current hardware that we have and the typical conditions for servicing satellites,” Talavage said.
The work was presented at the American Institute for Aeronautics and Astronautics’ SciTech Forum conference in Orlando.