MORE than a million robots work in factories around the world, most of them building cars. But in the view of many experts these machines are akin to the mainframe computers of old: big, expensive, inflexible and requiring teams of specialists to instruct them what to do. One of those experts, Rodney Brooks, has long argued that what industry needs is the robotic equivalent of the PC. In October, the result of his thinking will go on sale in the form of a robot called Baxter.

Dr Brooks is a former director of the Massachusetts Institute of Technology’s artificial-intelligence laboratory and co-founder of iRobot, which makes ’bots that do the vacuum cleaning and others that help soldiers defuse bombs. His new firm, Rethink Robotics, based in Boston, has produced a hulking two-armed robot that sits on a movable pedestal. Instead of a face, it has a comic pair of eyes displayed on a screen attached to its head.

Despite its countenance, Baxter is an extremely serious machine. Most industrial robots move rapidly and have to be caged to prevent them accidentally injuring anyone who comes near. They make precise but rigid movements, which is what you need when welding a car body. Baxter, however, moves with less determination because it compensates for changes in its environment. This means it can work safely alongside people.

Baxter uses a sonar located in its head to detect anyone nearby. If it spots someone, it slows down what it is doing. And instead of it having motors driving gears that operate its joints directly, Baxter’s gears drive a spring which in turn moves the joint. This gives the robot’s movements a degree of elasticity which, coupled with force sensors, provides a feedback mechanism. So, if you get in the way of its arm, for instance, it will sense that force and slow down or stop.

Programming the robot is simply a matter of moving its arms and manipulator fingers through the required motions, such as picking up items on a conveyor belt and putting them into boxes. Five cameras provide guidance, allowing Baxter to adjust automatically if items turn up in different positions, or if it drops something.

The cartoon eyes are used to produce expressions that can be identified quickly and easily by nearby workers, allowing them to determine how well Baxter is doing. For instance, the eyes look towards the place where one of its arms will move next and give a surprised expression if something unexpected is encountered there. The screen also provides information while the robot is being trained to carry out a task.

At $22,000, Baxter costs barely a tenth of some automated production-line systems. That works out at less than a dollar an hour if the robot operates around the clock for six days a week over three years. Its low cost and flexibility, Dr Brooks hopes, will allow companies to undertake in their home markets some of the assembly work currently done offshore in places with lower costs.

Next year, Rethink Robotics will make development kits available to researchers and inventors, allowing them to teach Baxter yet more innovative tricks. That might even put a smile on its face.