Scientists have taught a robot to use a flexible cutting wire

Robots usually find it difficult to understand soft surfaces. For example, a nice fluffy snow may trick some robots into thinking that it’s a stable surface. At the same time, robots do not have the best of luck working with flexible tools.

Now computer scientists from the ETH Zürich have developed a hot-​wire cutter robot, working with a flexible cutting wire.

This two-armed robot is handling a hot-wire, used to cut soft plastics. It is utilizing the bending of the wire to get complex shapes. Image credit: ETH Zürich

Hot-wire cutters are literally what you think they are – they are machines that use a heated wire to cut through stuff. Usually they cut various plastics, such as styrofoam. Hot-wire cutters with rigid wires are quite limited in shapes that they can cut. However, this new robot that ETH Zürich scientists named RoboCut is different. It has a bending wire, which allows cutting curves much more easily. This should cut down on production times, because this robot could approximate the targeted shape much more closely. At the same time, less material would be wasted. However, robots don’t handle bendy things very well.

The tricky puzzle of this research was actually calculations. Scientists had to optimize new ways to estimate the optimal tool paths to cut out desired shapes. The reaction of the wire to the movements of the robot arms had to be calculated. Scientists had to take into account the fact that the wire will break if handled in a wrong way. Then scientists had to design the program to determine the cutting sequence that would result in the desired shape. The basis for this technology is this two-armed Yumi robot from ABB. Scientists also had to make sure that arms are not going to collide and the robot will operate in a safe way for itself.

Demonstration of the robotic flexible hot-wire technology:

Simon Dünser, one of the scientists in this project, said: “The complex optimisation calculations are what make RoboCut special. These are needed to find the most efficient tool paths possible while melting the desired shape from the polystyrene block as precisely as possible”.

Although scientists developed this technology as a hot-wire cutter, it is not limited to that. The foundation of this technology could be applied to other cutting and milling operations. However, obviously, those other areas are already well-developed in terms of tool path design. Hot-wire cutting is a good method to perfect some shapes and prototyping. A bendy wire just makes this operation more efficient and more effective.

Pick up a wire, hold it on its ends and move your hands around to bend it. Pretty soon you will find out that it’s very difficult to do it in such a way that you could get some kind of a shape. This makes it very exciting that a robot can now have such capabilities that may enhance manufacturing processes.