MARM Is a Tripedal Robot Designed for Work in Space

As we accelerate towards industrial space operations, the need for robots that can work in space becomes more pressing. For a multitude of reasons related to both safety and practicality, astronauts keep EVA (Extra Vehicular Activity) tasks in space to a minimum. But those tasks will become a necessity as asteroid mining and other industries grow. They present an obvious need for versatile robots that can perform as much work as possible, from spacecraft repair to equipment setup and maintenance. MARM (Multi-Arm Relocatable Manipulator) is a tripedal robot designed and manufactured by engineers from IIT (Italian Institute of Technology) for such use in space.

MARM looks strange — almost alien — but is quite practical. Its design is the result of careful consideration into both potential use cases and real world limitations. For example, robots with four or six legs are far more common and exhibit a more stable gait, but those extra legs would add weight and increase the cost of launching MARM into orbit. Because MARM would operate in low-gravity environments, three legs is enough for locomotion and manipulation. It can use one leg to grasp and carry parts, and the other two legs for EVA walks while maintaining at least one point of contact at any given time.

Each of the three legs has six degrees of freedom (DoF), which is comparable to common industrial robot arms. The engineers arranged the legs for radial symmetry to prioritize versatility, so the robot’s capability doesn’t rely on orientation. Even in Earth gravity, it can balance on two legs and use the third for manipulation. In space, it might not experience any appreciable gravity. But the ability to operate even in relatively high gravity environments gives it potential for working on large asteroids like Ceres and even other planets and moons.

The IIT engineers designed MARM primarily for use on spacecraft that have the benefit of predictable structure. MARM can use its manipulators to latch onto points on that structure to move around the exterior of the craft while carrying its payload. That payload could, for instance, be a hexagonal tile that needs replacement. When equipped with the proper tools, it has enough dexterity to perform such repairs on its own, while human astronauts remain safely inside the spacecraft. And fully autonomous space operations will require robots like MARM to do all of the work.