Library robots

blue robotLibraries have always been at the forefront of adopting new technology, but their innovations usually have something to do with organizing and retrieving information. The online library catalog is a good example. Now some libraries are borrowing technology from manufacturing: robots that shelve and retrieve physical books.

It may come as a surprise to some people that printed books are still such a big deal to academic libraries. After all, much of formerly huge reference collections has been replaced by online databases. Long runs of many important journals and other periodicals are likewise available as full text online. Ebooks have lately begun to surpass printed books in sales.

Nonetheless, vast amounts of important information have never been digitized. It is accessible only in print form. While more and more library patrons use electronic information sources in preference to print, print cannot go away any time soon.

Problems with print collections

When I was a freshman in college, the university library had a closed stack policy. (This was in prehistoric times when there were not yet computers in libraries.) Students had to select materials from the card catalog, fill out a call slip, and wait (and wait, and wait) for someone on the library staff to retrieve the books. Sophomore year—oh joy!—the university opened a new library building with open stacks.

Missing items

Open stacks meant, of course, that anyone could go there and take books down. Patrons could check them out or sit in a nearby chair to read them. In that case, they either left them laying around or put them back on the shelf. It requires some training to reshelve books correctly, so more often than not, patrons misfiled them. One problem, therefore, is that as patrons trekked from the card catalog to the stacks (either in a vast underground space or a nine-story tower) they never knew if they would actually find what they were looking for.

Online library catalogs eventually solved part of that problem. When someone checked out a book, the catalog showed that it was in circulation and gave the date when it would be back in the library. That still did not solve the problem of misshelved books or books laying around on tables somewhere.


Even medium sized academic libraries own more than a million books and bound journals. They must be in some predictable order so that patrons and library staff can find any one of them in particular.

Bound periodicals may be shelved by title, but most materials are shelved according to the classification system used by the library (Dewey Decimal Classification, Library of Congress Classification, National Library of Medicine Classification, etc.). Shelving by classification puts short books and tall books close together, so there might be several inches of empty space between the top of one book and the bottom of the shelf above it.

Book stacks are usually no more than about six feet tall even though ceilings are much higher. The aisle between the stacks must be wide enough for two people to pass. Some libraries have adopted compact shelving for some of their less used materials. They save space by eliminating most of the aisle space.

Many libraries save shelf space in their main buildings by using off-site storage for infrequently used items. Typically someone on the library staff makes one or two trips there per day on a regular schedule. Patrons can still get access to these materials, but they have to wait several hours or even until the next day.

Preservation issues

Most patrons probably don’t give the physical safety of the books much thought, but some shelving designs make it awfully easy to inflict great harm on a book simply by putting it on the shelf. For example, some shelves have a thin metal divider that keeps books standing upright when several of them have been removed. Whoever puts the books back must be careful. Otherwise, the inside of the book can be pushed up against the divider, bending or tearing several pages.

Also, books thrive in an environment of controlled temperature and humidity. About 60 degrees Fahrenheit and 30% relative humidity is ideal. Humans are not comfortable in those conditions.

Robotic retrieval of reading material

library robot

Robot book fetcher at the University of Utah

California State University at Northridge installed an Automatic Storage and Retrieval System (ASRS) in 1991. Since then, a couple of dozen academic libraries have followed suit, either because of the opportunity to build new library buildings or to perform radical renovations to existing buildings.

Basically, robots take over all responsibility for retrieving books and returning them to their place. That means both that the system need not be designed with human limitations in mind and that the stacks are unsafe for humans.

Instead of six feet tall, stacks can be any size. At the Mansueto Library at the University of Chicago, they are 50 feet tall and underground. Each stack runs the entire length of the building in temperature and humidity conditions that are optimal for book preservation. The Mansueto Library will ultimately house the university’s entire print collection.

An ASRS can house an entire library collection using about a seventh the space of conventional library shelving, space the library can use for any number of places for people to gather. It is very expensive to build and maintain, of course, but as it turns out, only about half the cost of compact shelving!

Robots do not read call numbers, so the books can be arranged by size. Actually, the robots do not retrieve individual books, but bins that hold about 100 books each. Each robotic crane can swiftly move both horizontally and vertically at the same time to find the appropriate bin.

Here is how the system works:

  1. A patron looks for the desired item in the online library catalog. Assuming that it is not already checked out to someone else, only a few clicks are necessary to call for the item
  2. The catalog communicates the request to the ASRS, directing it to retrieve the bin where the item is located.
  3. The ASRS gets the bin and delivers it to a waiting librarian within a couple of minutes.
  4. The library staffer’s computer screen tells exactly where in the bin the item is located and shows its barcode number.
  5. The staff person scans the barcode and takes the item to the nearby circulation desk, where the patron picks it up.
  6. When the item is returned to the circulation desk, a staffer scans the barcode again, which causes the ASRS to return the bin so the item can be replaced.

This process occurs hundreds of times every day. It completely solves the problem of missing books. It doesn’t matter whether the patron removes the item from the library for a couple of weeks or uses it in the library. Either it is in the bin or it is not, and the catalog reflects the current reality at any given moment.

It saves lots of staff time. It is no longer necessary to shelve books manually. Neither is the time-consuming and extremely tedious task of shelf-reading to find misshelved titles.

So far, it seems like the old closed stack libraries without the horrendous waits. What about the serendipity that comes from browsing the shelves? With a virtual bookshelf on the computer, it can be almost as good as physical browsing.

The virtual bookshelf shows books in call-number order. And it shows not only the physical books, but also the growing number of ebooks libraries own. It is even possible for the virtual bookshelf to display books held by other libraries that have book-sharing arrangements.

You no longer look inside a book on the shelf to see if it’s useful, but you can have it from the bin within five minutes. Not only that, but for most installations of ASRSs, you can go over and watch the robots in action. Cool!

Robot Visions (Library Journal)
How It Works: Underground Robot Library (Popular Science)
Miller Nichols Library and Learning Center Expansion and Renovation: About the Robot (University of Missouri at Kansas City)
Books Flowing into New NCSU Library’s Robotic Stacks (North Carolina State University)

Image credits:
Blue robot. Some rights reserved by Nemo.
Robot book fetcher. Some rights reserved by skyfallery.

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