Ingeniero

 2010 WIETE

World Transactions on Engineering and Technology Education
Vol.8, No.4, 2010

An intelligent line-following robot project for introductory robot courses
Juing-Huei Su, Chyi-Shyong Lee, Hsin-Hsiung Huang, Sheng-Hsiung Chuang & Chih-Yuan Lin
Lunghwa University of Science and Technology
Taoyuan County, Taiwan

ABSTRACT: Line-following robots are very popular with technicaluniversity and vocational high-school students in
Taiwan. Therefore, these projects are quite helpful in motivating students to learn actively the implementation skills for
intelligent mobile robots. The line-following robot devised in this article for educational purposes includes not only
accurate line detection algorithms with analog outputs of reflective optical sensors , but also home-madeencoders,
which help record all information about the racing track. Th e firmware can then plan profiles for the fastest run. The
integration of the software control algorithms and hardware circuits make it a suitable teaching aid for introductory
autonomous mobile robot courses. The devised robot won first prize in several national contests for line-following
robots, which shows itssuperiority of implementation.

INTRODUCTION
Learning by doing is a very effective idea for students to acquire knowledg e, if they are well motivated. It was found
that students will be willing to do tedious research work to solve practical problems when these problems are related to
an interesting and competitive contest [1][2]. Racing contests of line-following robots are examples [1][3-5].Linefollowing robots are self-operating robots that move along a line on the floor. Recently, the Fortune Institute of
Technology held six line-following robot racing contests to encourage students from the technological and vocational
education system in Taiwan to show their creativity and techniques [3]. It is a very successful contest not only because
of the high prize, but also in attracting seniorhigh school students to join the contest. The Taiwan micromouse and
intelligent robot contest even included the line-following robot racing contest as a major event last year [5]. The rules,
which are similar to those in Japan [4], encourage line-following robot contestants to memorise what the racing track is
like by providing hints along the line whenever the curvature is changed. Thecontestants, therefore, can plan the speed
command profiles for their motors for straight -line segments and curves.
In addition to the intelligence of judging precisely where the line is, of memorising the racing track patterns and of
speed command profile planning for motors, the mechanical parts and design of the line -following robot are also
important to reduce the effect of weight transfer andto prevent skidding when making turns at high speeds. According
to the experience of the micromouse world champion [6], the turn speed is a decisive factor in robot speed contests. To
make a line-following robot with a speed faster than 1m/sec even when it is making turns, the correct prediction of the
line position is a key factor.
Unfortunately, algorithms which are able to predict accurateline position depend heavily on the assumption that
reflective optical sensors have similar output characteristics. It is also found that the spacing between reflective optical
sensors and the distance between the reflective optical sensor and the ground are important factors for line detection
algorithms to work accurately. Therefore, calibration of the reflective optical sensor outputs is animportant procedure
for a fast line-following robot. The calibration procedure described in Chan’s Web page uses white paper and a gain
value for each reflective optical sensor to adjust the corresponding output value to a pre-specified value [7]. Lee et al
use a more complex approach which needs 20% and 80% of grey patterns t o determine the calibration parameters
[8][9]. Although the...