Four-Track Vehicles by Bond Graph -
Dynamic Characteristics of Four-Track Vehicles in Snow
Katsuya SUZUKI Shigeo AWAZU
Tottori University Toyota Motor Corporation
2-74, Sumire-dai, Seto, 489-0904 1200, Mishuku, Susono, 410-1193,
Aichi, Japan Shizuoka, Japan
Abstract
The dynamic running performance of the four-track
vehicle (known as crawler vehicle) in the deep snow is
analyzed.
The modeling of the vehicle is easily completed by use of
the bond graph.
The simulation results by use of Bond Graph software
20-sim is as follows: The fundamental mechanism of the
vehicle running in the deep snow is that the crawler unit
is swung by the resistance of the snow around the center
of the drive shaft. Furthermore the frequency and
amplitude of the swing is changed with the amount of the
snow resistance.
1. INTRODUCTION
The four-track vehicle (known as a crawler
vehicle) is a particular kind of track vehicle
whereby the tires of an ordinary 4-wheel-drive
vehicle are replaced with triangular track units
attached independently to each wheel.
The track units have a contact surface area of 0.3
square meters approximately, about 15 times the
area of the tires.
Their low contact surface pressure contributes to
their superior driveability on snow, sand, mud and
other soft surfaces.
The driveability of four-track vehicles on snow
have been studied [Kitano et al.,1991].
However analysis has not yet been carried out on
the dynamic four-track vehicle, including the
dynamic motion of the track unit.
Thus, in this paper, we analyze the driveability of
the four-track vehicle on snow by use of the bond
graph. We also present the mechanisms of
driveability on snow.
Fig.1. Track Unit and its Attachment
2. DRIVEABILITY OF FOUR-TRACK VEHICLE
Fig.1 shows the track unit, which is mounted on the
vehicle [Awazu et al., 1999]. As shown in Fig.1,
the track unit as conventional tires is attached to the
hub with bolts and nuts through a disk called an
adapter.
A swing motion of the unit is not restricted around
the rotational driving axle.
Consequently, the track unit swings to follow the
shape of the road surface, as maximizing its contact
area with the road.
Driveability of the four-track vehicle on snow is
divided in the following two ability: (1) running
performance on trodden snow which is the same
performance as a vehicle with tires, (2) driving
ability in deep snow, where vehicles with tires can
not drive through.
In this paper driveability in deep snow is
investigated.
The photo in Fig.2 shows the four-track vehicle
driving through almost 1 meter deep of the new
snow, where it sinks 30-50 cm into snow.
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