Simulation of complex articulated commercial vehicles for different driving manoeuvres G. Isiklar

96 Pages·2007·4.16 MB·English

Simulation of complex articulated
commercial vehicles for different
driving manoeuvres

G. Isiklar

DCT 2007.122

Master’s thesis

Supervisor and member of the graduation committee:
Dr. Ir. I.J.M. Besselink (Eindhoven University of Technology)
Prof. Dr. H. Nijmeijer (Eindhoven University of Technology)

Member of the graduation committee:
Dr. P.A. Veenhuizen (Eindhoven University of Technology)
H. Verbeek (Nooteboom Trailers B.V.)

Eindhoven University of Technology
Department of Mechanical Engineering
Dynamics and Control Group

Eindhoven, September, 2007
ABSTRACT

Longer and heavier commercial vehicles (so called LHV’s) are used for
transportation of goods because of their economical advantages such as reduction of the fuel
consumption and increased cargo transportation per driver. The Dutch Ministry of Transport,
Public Works and Water Management has carried out a follow-up experiment with LHV’s on
roads in the period starting middle of 2004 until November 2006. This experiment includes
LHV’s which are longer and heavier than presently allowed in the Netherlands without a
release. It is only allowed to use the LHV’s in the Netherlands. In this thesis, the dynamic
behaviour and stability of these vehicles are investigated and compared with the reference
vehicle (tractor-semitrailer). The main goal of this thesis is extend the existing library in
SimMechanics/Matlab and simulate the performance of LHV’s for different driving
manoeuvres.
Geometrical dimensions, mass and inertia of the truck and trailer are collected from
previous research. Reference parameters for each unit are specified to be able to build up
different truck/trailer types. After completing the library, a simulation model of each vehicle
type is developed to analyse the behaviour for different manoeuvres.
Based on a literature study, it is decided that swept path width, low speed offtracking
and high speed offtracking are crucial performance measures. These measures are calculated
for each vehicle type under the appropriate driving conditions. In the swept path analysis, a
step steer angle is applied to the model as input and then swept path width is calculated as a
performance parameter. On the low and high speed offtracking, the desired path of the center
of the front axle is described as input and these performance parameters are compared to
each other. It is concluded from these manoeuvres that swept path and low speed offtracking
of tractor-semitrailer-semitrailer is greater than that of others. However, truck-2 axle drawbar
trailer-2 axle drawbar trailer vehicle displays the worst performance in high speed
offtracking. As it has a maximum number of turning points and is longer than other vehicle
types, the rearmost trailer has more chance to shift in lateral direction.
The static rollover threshold is taken as reference parameter when a vehicle follows a
circular path with fixed radius. In the lane change manoeuvre, rearward amplification and
dynamic load transfer ratio are evaluated to compare performances of articulated vehicles.
Tractor-semitrailer-2 axle drawbar trailer rolls over at the lowest longitudinal velocity when
it makes steady turn with fixed radius. Truck-2 axle drawbar trailer-2 axle drawbar trailer has
the most chance to roll over when it executes a lane change manoeuvre.

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CONTENTS

Abstract......................................................................................................................... i

Contents………………………………………………………………………………. ii

Symbols………………………………………………………………………………. iv

Chapter 1 Introduction
1.1 Background…………………………….......................................................... 1
1.2 Overview of Vehicle Combinations……………………………..................... 2
1.3 Problem Statement……………………………............................................... 3
1.4 Outline of The Report…………………………….......................................... 4

Chapter 2 Literature Study
2.1 Vehicle Combinations………………….......................................................... 5
2.2 Swept Path………………………………........................................................ 8
2.3 Low Speed Offtracking……………………………………………………… 9
2.4 High Speed Offtracking……………………………………………………... 9
2.5 Rollover Analysis………………………………............................................. 10
2.5.1 The Static Rollover of Heavy Trucks………………………………….. 11
2.5.2 Steady Turn With Constant Speed…………………………………….. 16
2.5.3 Dynamic Consideration of Rollover of Heavy Trucks………………… 16
2.5.4 Lane Change Manoeuvre……………………………………………… 17

Chapter 3 The SimMechanics Commercial Vehicle Library
3.1 The Purpose of Computer Based Modeling and SimMechanics Toolbox…... 19
3.2 Design Principles of The Commercial Vehicle Library……………………... 20
3.3 Descriptions of The Library Sections………………………………………... 23
3.3.1 Vehicles………………........................................................................... 23
3.3.2 Trailers………………............................................................................ 25
3.4 A Path Following Driver Model……………………………………………... 30
3.5 Visualization of The Models………………………………………………… 31

Chapter 4 Steady State Performance
4.1 Static Analysis………….................................................................................. 33
4.2 Swept Path Analysis…………......................................................................... 34
4.3 Low Speed Offtracking Analysis…………..................................................... 36
4.4 High Speed Offtracking Analysis………….................................................... 38

Chapter 5 Rollover Analysis
5.1 Steady Turn With Fixed Radius Manoeuvre………….................................... 40
5.2 Lane Change Manoeuvre…...……….............................................................. 42

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Chapter 6 Conclusions and Recommendations
6.1 Conclusions………………………………………………………………….. 47
6.2 Recommendations for future work…………………………………………... 48

References……………………………………………………………………………. 50

Appendix A : Tractor-Semitrailer-2 Axle Drawbar Trailer (Configuration-A)… 52
Appendix B : Tractor-Semitrailer-Semitrailer (Configuration-B)……………….. 57
Appendix C : Truck-Trailer (Configuration-C)…………………………………… 62
Appendix D : Truck-Dolly-Semitrailer (Configuration-D)...................................... 66
Appendix E : Truck-2 Axle Drawbar Trailer-2 Axle Drawbar Trailer 71
(Configuration-E).........................................................................................................
Appendix F : Truck-Semitrailer (Configuration-F)………………………………. 76
Appendix G : Truck-3 Axle Drawbar Trailer (Configuration-G)………………... 81
Appendix H : Tractor-Semitrailer (Reference Vehicle)…………………………... 86

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SYMBOLS
Symbol Description Unit
Capital
M Primary overturning moment [Nm]
OM
M Displacement moment [Nm]
DM
M Load Transfer Moment [Nm]
TM
F Vertical force applied to the right tyre [N ]
1
F Vertical force applied to the left tyre [N ]
2
T Track width of the vehicle [m]
LHV Longer and heavier commercial vehicle [-]
SRT Static rollover threshold [m/s2]
RA Rearward amplification [-]
DLTR Dynamic load transfer ratio [-]
K Gain [rad /m]
L Preview distance from the front axle [m]

Normal
l Truck length in configuration-C [m]
newtruck
m Mass of vehicle [kg]
a Lateral acceleration [m/s2]
y
h Height of the vehicle’s center of gravity [m]
cm
g Gravitational constant [m/s2]
∆y Lateral shift of the vehicle’s center of gravity [m]
d The lateral displacement of the center of the [m]
front axle in lane change manoeuvre
x The longitudinal position of the vehicle relative [m]
to the starting point of the lane change path
x The terminal point of the lane change trajectory [m]
e
y The trajectory of the center of the front axle in [m]
lane change manoeuvre
c Steering sensitivity [-]
1

Greek
φ Vehicle’s roll angle with respect to a point on [rad ]
the ground at the center of the track
θ Pitch angle [rad ]
ψ Yaw angle [rad ]
δ Steer angle [rad ]
ψ Look ahead angle [rad ]
ps

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Subscript
L Left side
R Right side
i Number of axle
k The first axle of the roll unit
l The last axle of the roll unit

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CHAPTER 1

INTRODUCTION

1.1 Background

Road transport is a favorable method for the delivery of a wide range of goods from
the producer to customer. Different types of vehicles are used for the transportation of goods.
Because of the economic advantages of longer and heavier commercial vehicles (so called
LHV’s), they are preferred as transportation vehicles.
The use of LHV’s reduces the number of rides and the mileages of inland transport.
As a result, the fuel consumption per ton cargo transported is reduced by allowing longer and
heavier vehicle combination. A reduction of 30 to 40% on fuel consumption can be expected.
This also leads to a decrease of emissions in the exhaust gases and noise. Moreover, more
cargo is transported per driver. So the total cost per mile for LHV’s decreases and it has
economic benefits.
Apart from the economic and environmental advantages of the LHV’s, they should
not be less safe than the normal commercial vehicles. The safety of these LHV combinations
is a major concern. According to data from the National Highway Traffic Safety
Administration (NHTSA) reporting the total number of accidents in United States [1], for
instance, shows that 3.7% of Large Truck Accidents in the United States in 2004 is caused by
rollover. However, it is concluded from the NHTSA that the percentage of rollover accidents
in fatal large truck accidents in the United States for the same year is 13.1% and its
percentage in injury large truck accidents is 10.0%. The severity of rollover truck accidents is
depicted in figure 1.1.
Severity of Rollover Truck Accidents in U.S. Truck Accidents in 2004
13.1
14
10.0
e 12
g
ar%)
L 10
ver nts ( 8
oe
Rollccid 6
nt of uck A 4 1.9
er
rcT 2
e
P
0
Fatal Accident Injury Accident Property-Damage-
Only Accident
Accident Severity

Figure 1.1 : Severity of rollover truck accidents in the United States in 2004
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It is also concluded from the Traffic Safety Facts 2004 prepared by NHTSA that
15000 large truck accidents are defined as rollover accident. 3.3% of total single-unit truck
accidents are rollover accidents. On the other hand, 4.0% of the combination truck accidents
are rollover accidents. Here a single-unit truck means a medium or heavy truck in which the
engine, cabin, drive train and cargo area are all on one chassis. The combination truck is a
truck/ tractor not pulling a trailer or a tractor pulling at least one full or semitrailer or a single
unit truck pulling at least one trailer.
Other statistical work performed by the Ministry of Transport, Public Works and
Water Management in the Netherlands shows that 2.37%, 21.7% and 41.5% of rollover truck
accidents in 2004 have respectively resulted in killed, hospitalized and injured of truck
drivers [6]. Another study by Kusters shows that the majority of rollover accidents in the
Netherlands occur for articulated heavy vehicles, including tractor-semitrailer and tractor-
trailer combinations and on highways [2]. These accidents are caused by excessive velocities
during cornering, load shift and sudden course deviation including high initial longitudinal
velocity with sudden braking.
This statistical data proves that a commercial truck rollover accident is the most
harmful event in the highway accidents. It results in significant damage to the vehicle and
injuries to the occupants of the truck. Furthermore, large traffic jams occur on the densely
populated Dutch roads resulting in economical losses. So a detailed study, in this report, is
made to analyse the behaviour of the various LHV combinations under critical driving
conditions.

1.2 Overview of Vehicle Combinations

As indicated in the previous section, dangerous roll and handling instabilities may
occur on articulated vehicles. For this reason, government specifies and restricts some
important dimensions of these vehicle types.
The Dutch Ministry of Transport, Public Works and Water Management has carried
out an experiment with Longer and Heavier Vehicle Combinations on urban and rural roads
in the period starting mid 2004 until November 2006. The LHV’s included in this experiment
have been longer and heavier than currently allowed in the Netherlands without a release.
The experiment has been applied to different vehicle combinations with a maximum
gross mass of 60 ton (allowed by Dutch law : 40/50 ton), a maximum length of 25,25 m
(allowed by Dutch law : 18,75 m) and maximum two turning points. The purposes of this
experiment have been to make generalizations at the national level about the accident risk
and the macroeconomic results of allowing LHV’s in the Netherlands. 100 companies and
300 LHV’s have participated in this experiment. As a result of this experiment, different
types of vehicle combinations indicated in table 1.1 are allowed on the Dutch roads.

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Configuration Components Figure

A Tractor – Semitrailer -
2 Axle Drawbar Trailer

B Tractor – Semitrailer –
Semitrailer (B-double)

C Truck – Trailer

D Truck – Dolly –
Semitrailer

E Truck – 2 Axle Drawbar
Trailer – 2 Axle Drawbar

Trailer

F Truck-Semitrailer

G Truck – 3 Axle Drawbar
Trailer

Table 1.1 : Different articulated commercial vehicle combinations [12]

1.3 Problem Statement

The Dutch Ministry of Transport, Public Works and Water Management has executed
experiments in order to investigate the dynamic behavior and stability of the different LHV
combinations. It is, however, difficult to assess their safety and to evaluate hazardous driving
situations by experiments only. It is also expensive to apply these types of experiments in
order to analyse the dynamic behaviour of commercial vehicles. Furthermore, properties of
parts modeled by using a computer program are easily modified and these parts are tested
and compared in short time with loaded and unloaded conditions. In this thesis, the parts of
the different vehicle combinations are modeled by using the SimMechanics multibody
toolbox of MATLAB/Simulink and a library has been created, which allows to build up
different vehicle combinations.

The main goals of this master thesis are :
•
To review literature to find exact requirements of LHV’s such as dimensional
restrictions and maximum load and to get familiar with dynamic behaviour of

articulated commercial vehicles.
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•
To extend the existing library in SimMechanics/Matlab in order to include the

various truck and trailer types as defined in table 1.1.
• To apply critical driving manoeuvres, to analyse the simulation results based
on performance criteria and to determine some basic properties of each
configuration type.

1.4 Outline of The Report

This report is organized as follows. A literature study is presented in chapter 2. First
of all, this study is performed in order to get ideas about the longer and heavier vehicle types,
driving manoeuvres and performance measurements such as swept path width, low and high
speed offtracking. Secondly, the mechanic and dynamic considerations of rollover of
articulated vehicles are presented to compare the performance of each configuration type for
extreme driving conditions. In chapter 3, it is shortly explained the purpose of computer
based modeling and the Simulink/SimMechanics Commercial Vehicle Library, which is used
to construct seven vehicle types. Furthermore, the properties of each subsystem used in this
library such as reference parameters, connection couplings are described in this chapter. A
driver model is developed to keep the vehicle in the desired trajectory.
In chapter 4, simulations for the various driving conditions are described in order to
calculate the steady-state vehicle performances, such as: static loads on the axles, the swept
path width, the low speed offtracking and the high speed ofttracking. Moreover, the results
obtained by simulations are compared to each other. In order to analyse the roll stability of
each articulated vehicle, the mechanic and dynamic analysis of rollover of each LHV are
described in chapter 5. After implementing the steady turning and standard lane change
manoeuvre, the static rollover threshold and maximum rearward amplification of each
vehicle are calculated. Finally with these results, conclusions are drawn and
recommendations for future research are given in chapter 6.

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