The machinery of the human body is wonderfully complex, especially in its moving parts. That's why recreating it in metal and plastic is commonly thought to be the stuff of science fiction, androids and bionic men. But professor Hugh Herr, director of the Biomechatronics Group at MIT's Media Lab, has made a career of taking the fiction out of the science. His team has developed, among other marvels, a prosthetic ``Rheo Knee" that uses artificial intelligence to replicate the workings of a biological human joint ... ... ``The amputee can think, contract muscles, and directly control the artificial leg. It's...