Wearable robots that are "rovable", that is, that move all around on your unmodified clothing, have been created by researchers from MIT and Stanford. Take a look at the prototypes in the video below.
(Rovable robot video)
We introduce Rovables, a miniature robot that can move freely on unmodified clothing. The robots are held in place by magnetic wheels, and can climb vertically. The robots are untethered and have an onboard battery, microcontroller, and wireless communications.
They also contain a low-power localization system that uses wheel encoders and IMU, allowing Rovables to perform limited autonomous navigation on the body. In the technical evaluations, we found that Rovables can operate continuously for 45 minutes and can carry up to 1.5N.
We propose an interaction space for mobile on-body devices spanning sensing, actuation, and interfaces, and develop application scenarios in that space.
Our applications include on-body sensing, modular displays, tactile feedback and interactive clothing and jewelry.
I think that physicist and science fiction author Robert Forward pretty accurately predicted these little rovables in his 1985 novel Rocheworld:
Each astronaut in the crew has a small subtree or "imp" that stays with him or her to act as the communication link to the main computer. Most of the crew have the tiny imp ride on their shoulder, although some of the women prefer to keep theirs in their hairdo. In addition to acting as the communication link to the computer, the imps also act as health monitors and personal servants. They are the ideal solution to the perennial problem of spacesuits ... scratching an itchy nose. The imps go into the spacesuit with the humans, and more than one human life was saved by an imp detecting and repairing a suit failure or patching a leak.
(Read more about the imp personal robot)