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Ch30-I044963.fm Page 145 Thursday, July 27, 2006 7:17 AM
Thursday, July 27, 2006
7:17 AM
Ch30-I044963.fm
Page 145
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DEVELOPMENT OF SENSORS
BASED ON THE FIXED STEWART PLATFORM

K. Irie, J. Kurata and H. Uchiyama

Department of Mechanical Systems Engineering, Kansai University
3-3-35, Yamate-cho, Suita, Osaka 564-8680, Japan

ABSTRACT

We propose new type of spatial vector sensor based on the Fixed Stewart Platform. Since six
measuring units are arranged in periodic and represented on the links of Stewart platform, the errors
accompanying each measurement axis are not accumulated. Our aim is focused to measure six
components of spatial vector, and we propose the structure composed without movable links. We
described the constructing method and the calculating solution from link parameters, which resulted
ease of the calculation. In order to confirm the validity of our proposal, the acceleration and
angular-acceleration sensor was manufactured. As the results of the triaxial acceleration measurement,
the validity of our sensor was confirmed as comparing with the performance of typical commercial
product.

KEY WORDS
Sensor, Accelerometer, Angular accelerometer, 6DOF, Method of measurement, Stewart platform

INTRODUCTION

Recently, many machines need much information on motion with six degrees of freedom more and
more. Tn these machines, the measuring instruments that can measure 6DOF motion are included,
and many multi-axis measuring sensors have been developed. However, it is generally very difficult
to measure 6DOF motion individually at once. A multi-axis measuring sensor measures each
component simultaneously although the influence of component to the others is curbed as much as
possible. Because of the reduction of this disadvantage, the structure of such kind of sensor seems to
be complicated and a measurement axis is restricted to a certain direction. Some of multiple sensors,
which can measure 6DOF motion, employ two kinds of sensors, they are three acceleration sensors
arranged according to the orthogonal coordinates and three angular-acceleration sensors put in center
of rotation. In our proposed sensor, six sensors of the same kind are employed and arranged
according to the special structure of sensor body like Stewart platform, for example Stewart (1965).
Six measurement sensor units are arranged along the parallel structure represented on the Stewart
platform so that the errors in each measurement axis are not accumulated. In our proposed structure,