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BASIC STUDY ON THE REAL-TIME THREE-DIMENSIONAL POSITION MEASUREMENT OF 
GROUND MOVING OBJECTS USING AN ACCELEROMETER AND GYROS 
Yoshiwo OKAMOTO*, Toshio KOIZUMI**, Yasuyuki SIRAI*** 
*Dep. Electrical, Electronics and Computer engineering, Professor, Chiba Institute of Technology, 
2-17-1, Tsudanuma, Narashino-shi, Chiba 275-0016, Japan - okamoto(@ec.it-chiba.ac.ip 
**Dep. Architecture and Civil Eng., Professor, Chiba Institute of Technology, 
2-17-1, Tsudanuma, Narashino-shi, Chiba 275-0016, Japan - koizumi(@pf.it-chiba.ac.jp 
***Dep. Design, Associate Professor, Chiba Institute of Technology, 
2-17-1, Tsudanuma, Narashino-shi, Chiba 275-0016, Japan - shirai@pf.it-chiba.ac.jp 
  
  
  
Commission I, WG 12 
Keywords: Surveying, Development, Measurement, Navigation, Platforms, Mobile, Three-dimensional 
ABSTRACT 
In recent years, electronics and computer technology have been applied to the development of survey instruments, and 
the methods of measurement have widely changed. We make use of sophisticated systems in daily base such as Total- 
Station, GPS and Laser-scanner, to name a few. However, a system based on light wave and/or radio wave has a 
weakness that it would not work if the waves were intercepted. An inertial survey system, on the other hand, functions 
independently of those waves, and it must be convenient under such circumstances. Therefore the authors are 
developing a portable and low-priced strap-down inertial navigation system. In this paper, the results from the field tests 
are presented, which have been performed on the equipment made on an experimental basis in order to investigate how 
the accuracy depends on the measurement strategy, namely the nonstop or the stop-and-go strategy. 
I INTRODUCTION 
For mobile mapping and various other purposes, it is an 
important research subject to measure accurately the 
three-dimensional position of a platform on real-time 
basis. GPS has been commonly used for these purposes. 
However, GPS sometimes does not work in urban areas 
with a number of towering buildings and/or mountainous 
rural areas because of the electromagnetic interference or 
blockage. By making use of the technique known as 
“inertial survey”, the authors had developed a system 
capable of measuring three-dimensional position of a 
ground-moving object on a real-time basis using 
accelerometers and gyros even in an area where GPS 
does not work. In the inertial survey system, positions 
are determined by integrating accelerations and angular 
velocities obtained from sensors. Therefore, the accuracy 
decreases as the measuring time becomes longer because 
of the accumulation of errors. In order to overcome these 
difficulties, the authors propose a modified method in 
which stop-and-go procedures are repeated during one 
sequence of measurement, and the integrated value of 
acceleration (velocity) is forced to be zero at every 
Stoppage by subtracting linear drift so that errors do not 
accumulate any more. They also performed experimental 
measurements so as to evaluate the effectiveness of this 
method. Their results are shown in this paper. 
In this study, servo-type accelerometers and two 
types of gyros were used: one is the vibration gyro that is 
inexpensive but has somewhat lower performance, and 
the other is the fiber optical gyro with moderate 
performance. By attaching an accelerometer and a gyro 
to each of three mutually orthogonal axes, a strap-down 
inertial survey system was constructed. As a platform, a 
bicycle trailer was used. Experiments were performed on 
an asphalt-paved road with horizontal distance of about 
160 meters and level difference of about 6 meters. 
Resultant time courses of the platform location were 
compared with the actual ones in both the horizontal 
plane and vertical alignments of the road. Two kinds of 
measurement strategy were tested: the conventional one 
in which the equipment moves without any stoppage and 
the one with repeated stop-and-go, which had been 
proposed by the authors. They shall be called the nonstop 
strategy and the stop-and-go strategy, respectively, 
hereafter in this paper.