24-07-2012, 04:01 PM
An Enhanced Robotic Library System for an Off-Site Shelving Facility
An Enhanced Robotic Library.pdf (Size: 347.37 KB / Downloads: 22)
Abstract
This paper describes our continued work of a unique
robotics project, Comprehensive Access to Printed
Materials (CAPM), within the context of libraries. As
libraries provide a growing array of digital library
services and resources, they continue to acquire large
quantities of printed material. This combined pressure of
providing electronic and print-based resources and
services has led to severe space constraints for many
libraries, especially academic research libraries.
Consequently, many libraries have built or plan to build
off-site shelving facilities to accommodate printed
materials. An autonomous mobile robotic library system
has been developed to retrieve items from bookshelves and
carry them to scanning stations located in the off-site
shelving facility. This paper reviews the overall design of
the robot system and control systems, and reports the new
improvement in the accuracy of the robot performance; in
particular, the pick-up process.
Introduction
As libraries provide a growing array of digital library
services and resources, they continue to acquire large
quantities of printed material. This combined pressure of
providing electronic and print-based resources and services
has led to severe space constraints for many libraries,
especially academic research libraries. Consequently,
many libraries have built or plan to build off-site shelving
facilities to accommodate printed materials. However,
given that these locations are not usually within walking
distance of the main library, access to these materials,
specifically the ability to browse, is greatly reduced.
Libraries with such facilities offer extensive physical
delivery options from these facilities, sometimes offering
multiple deliveries per day. Even with such delivery
options, the ability to browse in real-time remains absent.
The goal of the CAPM Project is to build a robotic, ondemand
and batch scanning system that will allow for realtime
browsing of printed materials through a web interface.
We envisage the system will work as follows: an end user
will identify that a monograph is located in an off-site
facility.
Hardware of the Robotic System
Mechanical Structure
This section presents designs and descriptions of two major
components of the CAPM library robot: the manipulator
arm and the locomotion device.
Manipulator arm system
In order to retrieve books from bookshelves and carry them
to the scanning station, a specific manipulator arm system
was designed. Since each bookshelf is 10-foot-high, a
vertical translation system (VTS) was used to move the
robot manipulator to different altitudes. The VTS is a
sliding rod with an electric motor for driving a leadscrewed
rod. An enhanced commercial 6-DOF robot
manipulator, the F3 made by CRS Robotics, Inc., is affixed
to a platform which is a part of the vertical translation
system (See Figure 1.)
We built and installed a passive gripper to the endeffector
of the robot manipulator. The gripper is used to
passively grasp the bookcase. The structures of the gripper
and bookcases were designed to fit to each other. A
barcode scanner is installed inside the gripper in order to
recognize and ensure the precision of picking a requested
item.
Control and Software
All the processes and activities of the system are controlled
by an onboard Intel Pentium II laptop. The control systems
of the library robot consist of several sub-controllers: the
control system of the VTS, the control system of the robot
manipulator, the control system of the mobile platform, the
high-level control system of the library robot, and the
control software.
Improvement in the Accuracy of the Book
Pick-Up Process
To assist the motion planning of the library robot, the
complete working process of the library robot was
simulated using 3DSMAX. Based on the simulation, a
complete path was generated, and experiments were
executed to test and adjust the performance of the robot. To
simplify the implementation, a map-based scheme was
employed to control the mobile platform. A fixed global
coordinate system is defined with its origin at the docking
spot. The positions of the intermediate stops and the
destination were defined in the global system. An optimal
path was chosen to connect the current stop and the next
stop. The major problem appearing in the experiments is
positioning error. It was found that the positioning error
was closely related to the moving speed of the platform.
Conclusion
An autonomous robotic library system was built as a
prototype. The robot design, control systems, simulations,
experiments and results were presented. An implementation
using IR sensors and a new algorithm to enhance the
accuracy of an operation process, book pick-up process, was
described, and reported its successful experimental results.