Air hockey tables help develop work practices in space
Future construction workers look like oversized hockey pucks. They float them on an air cushion while they collect beams and assemble them into frames. These prototypes may lead to the development of robots, capable of building spacecraft systems such as giant arrays of solar panels. NASA is already imagining the construction of arrays 10 kilometers long.
Wei-Min Shen of the University of Southern California and his colleagues described the robots at the International Conference on Complex Systems, held last week in Boston, Massachusetts. Given the risks involved in manned space travel, many believe that robots are the best bet for building structures in space.
"Building buildings by astronauts would be too dangerous and expensive," says Shen. His group is collaborating with NASA in order to develop intelligent robotic systems that can coordinate their actions by themselves, so that there will be no need for close supervision and control by humans.
Several research groups have shown that teams of mobile robots, which are able to communicate with each other, are able to perform complex tasks: for example, they can work together to push a load along a surface. This is similar to the group intelligence that ants show when they perform collective tasks such as searching for food.
In space, on the other hand, there are complications such as working in a weightless and frictionless environment, which makes it difficult to control movements. Two robots, carrying different components in the structure, may easily collide or pass each other quickly.
To investigate such difficulties, Shen and his colleagues created a two-dimensional equivalent of space in the form of an air hockey table. Jets of air flow through a network of tiny holes in the tabletop, so the disk robots hover in a virtually frictionless environment.
The robots, which are about 30 centimeters wide, move with the help of four fans. Their movements are controlled remotely by a wireless transmitter, and a camera, which serves as eyes for the robots, follows their movements. Ultimately, the researchers intend to replace the central control system with autonomous sensing and control mechanisms for each robot.
An important feature of the robots is that a wire connects pairs of robots. This fact helps to prevent individual robots from getting out of control and helps to keep them close, so that they can assemble the components they carry. When the strap connecting the robots is extended, each robot can move freely and search for building materials.
So far, the experiments have involved long, rigid beams with joints at their ends, which can be joined together to form flexible chains. As soon as the two robots in a certain pair have each found a beam, they lift the beams with the help of mechanical units, and the strap connecting them rolls in and pulls them and their cargo together.
Shen's robots have already become experts at this task. They have no problem finding two beams and connecting them. The next step will be to add a third beam and connect the three into a triangle.
"We are now working on the final stage," says Shen, who believes that the robots will be able to create such shapes very soon. Triangular foundations can be used as rigid structures, which can be assembled into larger structures such as supporting skeletons.
Translation: Dikla Oren
