IEEE Robotics & Automation Magazine - December 2013 - 157

calculating the necessary frames. The
gripper location is calculated, so that
the book is aligned to be parallel to the
" C , frame, e.g., the book cart's frame.
If T W
C is the book cart/book holder
frame, obtained from MVR, the alignment of the book is done using again
a similar form such as (1), that is,
W
C
C
TW
B = ^ T C $ T B h . The frame T B relates
the orientation of the book with the
book cart/book holder. It can be
extracted either by a database or geometrically. The gripper frame can be
calculated using (1). In general, for
each case the calculation of the relation
T CB between the gripped book and the
container, where it is going to be
placed, is the first step. Since a relative
frame T BG is assigned to each gripped
object, the pose of the end-effector can
be extracted.

Table 1. Success rate of the manipulation of 100 books in the
FRIEND library workplace scenario.
Execution

Task 1

Task 2

Task 3

Task 4

The Complete
Sequence of Tasks

Autonomous

84%

83%

89%

84 %

62%

With user
interaction

99%

96%

99%

100%

95%

Table 2. User questionnaire results.

Average Answer in
Answer of the
User Acceptability
FRIEND IV End
Test of the FRIEND III User

Questions

Possible Answers

1) What is your first
impression about
FRIEND?

Positive
Negative
Scary
Strange

Positive

Very positive

2) Can FRIEND be
supportive in your
daily activities?

Very supportive
Yes
A little
No

Yes

Very supportive

3) Is FRIEND better

Yes

No

Neither ... nor

in assistance than No
Performance Evaluation
care-personnel?
To evaluate the performance of
4) Could FRIEND
Yes
No
No
FRIEND IV in executing the usage scereplace the careNo
personnel?
nario, an intensive test consisting of 100
5) Is FRIEND userYes
Yes
Yes
consecutive runs was performed. In
friendly?
No
each run, the complete sequence of
6) Could you imagine Yes
Yes
Yes
manipulation tasks was executed,
using FRIEND
No
which includes grasping the book from
once it is on the
market?
the book cart (Task 1), putting the
grasped book on the book holder (Task
2), grasping the book from book holder
after the user has completed the cataloging (Task 3), and returning the book on the lower shelf of on the results of the applied image processing algorithms.
the book cart (Task 4). In the case of the system failure in In the performed experiments, the implemented vision
autonomous execution of a specific task, the end user was method was able to detect the grasping point of the book
asked to complete the task through the HMI. Once the task to be manipulated correctly in 90 runs. The correct
was executed by the user, the system executed the subsequent detection means that the vision-based detected point was
task(s) autonomously. The experimental results show that between the gripper plates in the so-called tolerance area,
executing the scenario through the execution of the sequence as defined in [9]. However, in some cases, the cause of
of individual tasks helped the end user control the system the failure was an inability to grasp the book. This hapmanually in case of failure in autonomous task execution.
pened, for example, when the horizontally placed second
In the performed 100 runs, the robotic system together book on the shelf of the book cart (the book next to the
with the end user was able to successfully complete the vertically placed book to be manipulated) was too thin
sequence of four tasks in 95 (95%) runs. In 62 runs, the sys- (less than +1.7 cm, which is a width requirement for relitem was able to execute the sequence of all four tasks autono- able book grasping as detailed in [9]), so that the robot
mously. In 29 runs, the system failed in the autonomous exe- was not able to insert the left plate of the gripper in the
cuting of one task only, whereas in four runs the system failed gap between the first book (book to be manipulated) and
in the autonomous execution of more than one task. Table 1 the third book in a row, which was also vertically placed.
summarizes the experimental results. As evident, the average This resulted in the collision of the gripper with the third
success rate for the autonomous execution of individual tasks book. In such cases the user was asked to align the gripis 85%, while this rate increases to 98.5% for the execution per manually between the first and the third book using
with the end user interaction.
the HMI. Some of the failures in execution of Task 2, putThe success in the autonomous execution of Task 1, ting the grasped book on the book holder, were due to
grasping the book from the book cart, depends mainly the inaccurate computation of the book size, which
DECEMBER 2013

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IEEE ROBOTICS & AUTOMATION MAGAZINE

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157
Table of Contents for the Digital Edition of IEEE Robotics & Automation Magazine - December 2013
