RAVENS have a bad reputation. Medieval monks, who liked to give names to everything (even things that did not need them), came up with “an unkindness” as the collective noun for these corvids. Blake Hannaford and his colleagues at the University of Washington, in Seattle, however, hope to change the impression engendered by the word. They are about to release a flock of medical robots with wing-like arms, called Ravens, in the hope of stimulating innovation in the nascent field of robotic surgery.

Robot-assisted surgery today is dominated by the da Vinci Surgical System, a device that scales down a surgeon's hand movements in order to allow him to perform operations using tiny incisions. That leads to less tissue damage, and thus a quicker recovery for patients. Thousands of da Vincis have been made, and they are reckoned to be used in over 200,000 operations a year around the world, most commonly hysterectomies and prostate removals.

But the da Vinci is far from perfect. It is immobile and weighs more than half a tonne, which limits its deployability, and it costs $1.8m, which puts it beyond the reach of all but the richest institutions. It also uses proprietary software. Even if researchers keen to experiment with new robotic technologies and treatments could afford one, they cannot tinker with da Vinci's operating system.

None of that is true of the Raven. This device—originally developed for the American army by Dr Hannaford and Jacob Rosen of the University of California, Santa Cruz, as a prototype for robotic surgery on the battlefield—is compact, light and cheap (relatively speaking) at around $250,000. More importantly for academics, it is also the first surgical robot to use open-source software. Its Linux-based operating system allows anyone to modify and improve the original code, creating a way for researchers to experiment and collaborate.

Universities across America are taking delivery of the first brood of Ravens in February. At Harvard, Rob Howe and his team are hoping to use a Raven to operate on a beating heart, by automatically compensating for its motion. At the moment, heart surgery requires that the organ be stopped, and then restarted. At the University of California, Los Angeles, meanwhile, Warren Grundfest's experiments in communicating to the operator a sense of what the robot is feeling will attempt to give that operator a sense of touch while he is carrying out an operation. Pieter Abbeel and Ken Goldberg at the University of California, Berkeley, will try teaching the robot to operate autonomously by mimicking surgeons. And Dr Rosen himself will concentrate on replicating between man and machine the close working relationship that a team of human surgeons enjoys.

Crucially, although individual laboratories will retain the rights to their own particular innovations, the results of these studies, and the improvements they suggest, will be stored in an online repository that is available to all. What happens after that is less certain. The research-oriented Raven has not yet been approved by the Food and Drugs Administration for human surgery, so all of these investigations are, for the moment, restricted to operations on animals, or on human cadavers. That can be overcome with time, of course, once Ravens have been put through their paces often enough in this way. But there is another, legal, problem. Intuitive Surgical, the company behind the da Vinci, holds patents that could make launching a commercial competitor tricky—at least in the immediate future.

As Intuitive Surgical's patents gradually expire, however, the University of Washington is considering the possibility of spinning off the Raven into a start-up company. In the meantime, four more universities, including two outside America, have expressed an interest in buying one of the new robots. And even those without a quarter of million dollars to spare can participate in its development. The University of Washington is releasing a graphical simulation of the Raven that can be used to test its control system virtually. Dr Hannaford hopes that robotics researchers and even amateurs will then help to find and fix bugs in the open-source code—and that the kindness of strangers will thus help make Ravens kinder, too.