Sometimes even a frequent library-goer can get lost looking for a book among the many rows of unfamiliar shelves.

Ideas for a fully automated library that could make such searches easier have been around for decades, but they have either been too sophisticated, requiring the complete reconstruction of the library, or too expensive, with hundreds of thousands of robots needed for the job.

Chinese scientists believe they have come up with a simple, low-cost solution.

They propose a "smart carpet", which would use motion sensors under-foot to quite literally point visitors in the right direction.

They have developed a simple algorithm that would enable the carpet to identify and interact with tens of thousands of users simultaneously - enough for even the grandest of libraries.

Research on the carpet, by a team with the University of Science and Technology of China in Hefei , Anhui , was chosen as the "best paper" at the recent International Conference on Robot Intelligence Technology and Applications in Beijing.

Dr Sun Hao, co-author of the paper, said the smart carpet was simply ordinary fabric woven with pressure sensors.

He said the technology really came into its own when it was required to deal with complex requests.

"The larger and more sophisticated the building, the better," he said.

For example, in a huge library with hundreds of thousands of books, the smart carpet could connect to a person's smartphone through a cloud server, tracking his position and guiding him to a book as swiftly as he is able to walk.

"The direction guidance can be displayed on the user's smartphone, or under their feet as an LED arrow," Sun said.

Sun said the carpet would be far more accurate than surveillance cameras in sensing a person's location.

One problem with cameras was that their line of vision could be obscured by crowds - something that would not be a problem for the carpet.

The pressure sensors used by the carpet are cheap, as low as four yuan (HK$5) each, making mass production feasible.

"Once theoretical problems are solved and the lab tests finished, factories in Shenzhen can start production. What we have seen only in science fiction may soon become part of our lives," Sun said.

He foresaw a time when the carpets could exchange data with carpets in other cities and be in contact with other robots, leading to applications far beyond the library, such as in malls.

"Walking in the shopping mall will be like walking in the spaceship of WALL-E (Pixar's 2008 science fiction cartoon), where each person has a definite path marked under their feet."

For Liu Shunyi, a graduate student of physics at Beijing Normal University who often spends hours in libraries searching for rare books, the smart carpet seems "a good idea".

"Though many materials have been digitised, some are available only in physical formats," he said.

But he had a word of caution for the carpet developers. "To help me get to a book, the carpet needs to know not only where I am, but where the book is. Sometimes people replace the books on the wrong shelves."

Stephen Chen