6B-1-1
A Tracking System for Construction vehicles with DGPS and RTK-GPS
Shun’ichi OHTSU, Tomonori TAKADA, Tatsunori SADA
Technical Research Institute, Mitsui Construction CO., LTD.
518-1, Komaki, Nagareyama-city, Chiba, 270-0132
JAPAN
E-mail: ohtsu@mcc48.mcc.co.jp
KEY WORDS: GPS,DGPS,RTK-GPS, Tracking system
ABSTRACT
In recent years GPS technology has been introduced to operation control of construction vehicles, especially tracking the
rolling compaction machine. Tracking System using GPS is applied to embankment quality control which has been usually
executed by physical compaction test on the road construction in Japan.There are two real-time positioning and tracking
systems by GPS, one is differential GPS(DGPS) and the other real-time kinematic GPS (RTK GPS). Users can get
meter-level accuracy easily with DGPS which employs pseudorange meas-urement.Especially, in Japan, the DGPS
service by FM multiple broadcasting is spread all over the country for the vehicle navigation users, therefore, DGPS is
available with low cost at any place where FM can be received. On the other hand, RTK GPS employs a method carrier-
phase differential GPS positioning whereby users can obtain centimeter-level position accuracies in real time. But users
have to set local broadcasting system and the devices are more expensive than those of DGPS. The authors developed a
monitoring system for such construction machine operation using both DGPS and RTK GPS and evaluated both methods.
The system consists of GPS receivers, communication systems ( FM receiver, local com-munication system), monitors
and multi gate station (MGS). MGS receives multi receivers outputs ( DGPS and RTK GPS) changes the data formats and
sends the final outputs to the monitoring system. We had executed an experiment to compare both methods in accuracy ,
stability, and operability on the road construction field. As a result, we obtained 2 meter accuracy by DGPS and 2 cm
accuracy by RTK GPS, but there were some problems in RTK GPS about stability and operability. We concluded that
users should select the positioning and tracking method according to the accuracy requirement and other circumstances.
1. INTRODUCTION
In Japan, work has been under way in recent years to
develop GPS (Global Positioning System)-based systems
for managing construction vehicle operations. Many re
searchers are working, in particular, on the development
of systems that manages the quality of rolling by tracking
rolling equipment locations in real time by means of GPS.
High-accuracy GPS technology includes two real-time po
sitioning techniques: Differential GPS (DGPS) and Real-
Time Kinematic GPS (RTK-GPS). DGPS and RTK-GPS
provide real-time positioning accuracies of up to several
meters and several centimeters, respectively. In Japan,
DGPS service via FM multiplex broadcasts is available to
drivers in almost all parts of the country so that an
inexpensive DGPS system can be made a reality if posi
tioning accuracies of several meters are acceptable. An
RTK-GPS system, on the other hand, requires its own
reference station which transmits correction information.
RTK-GPS, therefore, is more expensive than DGPS
although the former is capable of more accurate posi
tioning.
The authors examined different GPS-based positioning
techniques to find a method suitable for monitoring con
struction vehicles, taking into consideration characteristics
of DGPS and RTK-GPS. Then, the authors developed a
monitoring system which makes combined use of DGPS
and RTK-GPS. This paper reports on the development
and application of a construction vehicle monitoring sys
tem using DGPS and RTK-GPS, focusing on the veri
fication of DGPS and RTK-GPS, on DGPS- and RTK-
GPS-based monitoring of construction vehicles, and par
ticularly on rolling work that requires real-time vehicle
management.
