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MINISTRY OF EDUCATION
AND TRAINING

MINISTRY OF AGRICULTURE
AND RURAL DEVELOPMENT

VIETNAM NATIONAL UNIVERSITY OF FORESTRY

LUONG ANH TUAN
STUDY ON THE DYNAMICS OF FIRE FIGHTING
MOTORCYCLES FOR THE OLD QUARTERS
IN HANOI CITY
MAJORITY: MECHANICAL ENGINEERING
CODE NO: 9520103

SUMMARY OF
ENGINEERING DOCTORAL THESIS

Ha Noi, 2022


Research work is completed at: Vietnam National University of
Forestry

Scientific instructors:
1. Assoc. Prof. Dr. TAI VAN DUONG
2. Dr. SON HOANG

Reviewer 1:
Reviewer 2:
Reviewer 3:

The defense will be taken in front of the Institutional Board of
Thesis Evaluation at: Vietnam National University of Forestry

At: … time, Date ….Month…..year 2022

The thesis can be found in the libraries:
National Library; Library - Vietnam National University of
Forestry; Library - Vinh Long University Of Technology Education


1

INTRODUCTION
1. The urgency of the thesis
To meet the requirements of fire fighting equipment for the old
town area, where there are narrow roads and small alleys in crowded
residential areas, the University of Fire Prevention has researched, designed
and manufactured successfully. Fire fighting motorcycles are used in the old
town areas, in narrow alleys, after researching and manufacturing, they have
been used in some localities such as Hanoi and Ho Chi Minh City. for good
fire fighting effect.
In the process of using a fire fighting motorbike, there are many
problems such as the front wheel of the vehicle being split when starting or
when crossing a bump on the road, the vehicle may overturn when turning
around in narrow alleys, vibrating. shaking the steering wheel when the
vehicle is in motion makes it difficult for the driver.
From the existence of the above-mentioned fire fighting
motorcycles, it is necessary to study the dynamics of fire fighting
motorcycles for the old quarters to serve as a scientific basis for the design

and manufacture of fire engines. for the old town areas, narrow alleys.
Stemming from the above reasons, the thesis conducted a study with the title:
"Study on the dynamics of fire fighting motorcycles for the old quarters in
Hanoi city".
2. Research objective of the thesis
Building a scientific basis to serve the calculation, design and
manufacture of fire fighting motorcycles for the old quarters to meet the
requirements of balance and stability of the vehicle when moving in narrow
alleys, to improve the mobility of fire engines.
3. Research subject
The research object selected by the thesis is the fire-fighting
motorcycle for the old quarters, designed and manufactured by the Ministry
of Public Security and used in some localities.
4. Research scope


- Building models, doing theoretical and experimental research to
find out some parameters for mounting specialized equipment for rescue
and fire fighting in vehicles. Ensure the vehicle's movement is stable,
gripping, not shaking and easy to drive.
- Build a kinematic model to calculate the vehicle's ability to
move through narrow corners and corners, as a basis for planning rescue
and fire fighting movements in the area.
5. New contributions of the thesis
1. The thesis has built a model and established a system of equations for the
linear motion of the fire engine when starting and moving through the road
surface, the results of the survey of the dynamic equation of the fire engine.
The fire engine has determined a number of reasonable parameters: the
height coordinates of the center of gravity of the equipment cluster
according to the height Zm= 75cm, the coordinates of the center of gravity

of the equipment cluster along the X axis is X m= 15cm, then the wheel In
front of the vehicle, the vehicle always clings to the road at all speeds ≤
70km/h and the load of the fire fighting equipment assembly on the vehicle
can be up to 130kg.
2. Having built a kinematic calculation model of a fire engine when turning
around, when moving through a narrow alley, a formula for calculating the
kinematic parameters of the vehicle has been established: speed. , angle of
inclination ... , investigated the kinematic equation of the vehicle moving
through narrow bends, from the survey results, a table of safe speeds
corresponding to the coefficient of sliding friction and turning radius was
obtained from the survey results. (Table 3.2) and the size table of vehicle
length corresponding to the vehicle width of 1m (table 3.3).
3. The thesis has developed an experimental research method and
determined a number of dynamic parameters of the fire engine, including:
coordinates of the vehicle's center of gravity, the stiffness of the shock
absorber, the moment of inertia , deformation of the front tire, displacement
of the driver's body, experimental results to verify the theoretical model and
complete calculation of the fire engine.


6. Scientific and practical significance of the thesis


6.1. Scientific significance of the thesis
The research results of the thesis have built a scientific basis to calculate
the design and manufacture of fire fighting motorcycles in the old town, and
at the same time, the thesis has built an empirical research methodology to
determine a number of parameters. dynamics of fire engines. From the results
of theoretical and experimental research, it is possible to make scientific
documents for calculating and determining the reasonable values of some

parameters of fire engines.
6.2. The practical significance of the thesis
The research results of the thesis are used for the design, manufacture and
completion of fire fighting motorcycles for the old quarters and narrow
alleys, in addition, they are also used as a reference for the design research.
Design and manufacture other specialized motorcycles.
Chapter 1
OVERVIEW OF RESEARCH ISSUES
1.1. Overview of research works on the dynamics of motorcycles
1.1.1. Research works on the dynamics of motorcycles in the world
The author Sharp, R.S published the article "Stability, control
response and steering of a motorcycle" [31], the author established the
equation of stability of the vehicle when the motorcycle was moving in a
straight line with the response. of motorcyclists, this study applies to
motorcycles without cargo.
Author Koenen, C published the doctoral thesis, Delft University:
"Motorcycle dynamics when running straight ahead and when cornering"
[32], the author built a model and established equations. for motorcycles
when the vehicle is moving in a straight line and when the vehicle enters a
roundabout with a change in vehicle speed, the study is for the vehicle
without cargo.
Breuer, T. and Pruckner, A., published work [34], which performed
advanced dynamics analysis and motor simulation, which investigated the
factors affecting the dynamics of motorcycles. motorcycles


and simulated motorcyclists on Matlab-Simulink software, the work has not
analyzed the dynamics of fire engines.
Sharp, R.S, Limebeer, D.J.N., published the work [35], the work
introduced a motorcycle model to analyze the stability and control control

parameters. for the case of the car moving on a straight road at a constant
speed.
In summary: In the world, there have been a number of published studies on
motorcycle dynamics, after which the above-mentioned studies mainly focus
on the study of motorcycles without cargo, there is no research work on fire
fighting motorcycles, special-use motorcycles.
1.2. Research projects on fire fighting motorcycles in Vietnam
Dr. Le Quang Bon University of Fire Prevention has successfully
carried out a project at the Ministry of Public Security: "Research, design,
and manufacture multi-function fire fighting and rescue motorcycles" [3], the
results of The project has successfully designed and manufactured a multifunction fire fighting and rescue motorcycle, this fire engine has been put
into use in the old quarters of Hanoi, Hoi An and Ho Chi Minh City. The
research results of the topic only focus on the design and manufacture, there
is no study on the dynamics of fire fighting motorcycles.
Assoc. Prof. Dr. Duong Van Tai has successfully researched forest
fire fighting motorbikes, the research results have designed, manufactured
and commercialized fire fighting motorbikes for a number of localities such
as Forest Rangers of Binh Phuoc Province, Forest Rangers of Thua Thien
Hue Province. Thien Hue, Management Board of Protection Forests and
Special-Use Forests in Hanoi [24].
In summary: In Vietnam, there have been a number of research works on
fire fighting motorcycles, however, the works only focus on design and
manufacture without any research on the dynamics of fire engines.
1.3. Research objectives of the thesis
From the research results obtained in the overview, the thesis sets out the
following research objectives:


Building a model, setting up a system of differential equations for
the motion of a fire engine when moving on a straight line and in a corner,

surveying a system of dynamic differential equations, to serve as a scientific
basis for the process of calculating and designing the old town fire fighting
motorbike in order to improve the vehicle's maneuverability.
Chapter 2
DYNAMIC FACILITIES OF FIRE MOTORCYCLE
2.1.2 General arrangement of fire engines
The general design model for a multi-purpose fire, rescue and rescue vehicle
is shown in Figure 2.1.

Figure 2.1: General layout of a multi-purpose fire, rescue and rescue
motorcycle
1- Priority whistle; 2- Priority flash; 3- Base vehicle (Kawasaki W175); 4Container for fire fighting tools; 5- Electric kickstands keep the vehicle
balanced during fire fighting activities; 6- Generator; 7- Containers
containing fire-fighting hoses; 8- Honda GX160 T2 engine fire pump; 9Priority mast lights; 10– Powder fire extinguisher; 11- Portable intermediate
water tank; 12- Roll of water suction hose; 13- Support frame; 14- Box
containing multi-purpose demolition tools, drills, lights, gas masks.
From the general structure model of the fire fighting motorcycle
shown in Figure 2.1, the thesis proceeds to build a dynamic model of the
motorcycle when it is moving on a straight road and in a narrow alley.
2.2. Building a model, setting up the dynamic equation of the
motorcycle when moving on a straight road
2.2.1. Flat motion model of fire fighting motorcycle


The flat motion model of the motorcycle is simulated by 5 pieces of
hardware: Suspension block (including chassis, engine, driver, fire and rescue
vehicle assembly, slider of the front fork), lower fork of the front fork
, rear fork, front wheel, rear wheel. These parts are linked together through
rotary joints, translational joints. Elastic coefficient and damping coefficient:

Cbr , kbr for the rear wheel and Cbf , kbf

for the front wheel. The rear and

front shock absorbers have elastic coefficients and damping coefficients
respectively : Cr ,

kr

and C f , k

. (Figure 2.2).

f

Choose the overall coordinate system O 1xyz, whose origin O1 is located at the
contact position between the rear tire and the road surface, the x-axis is in the
direction of the vehicle's forward direction, and the z-axis is up.
With the coordinate system selected as above, we have table 1 - the symbols
of the centroids of the clusters and their coordinates at the initial time (t=0)
and at the time of consideration t.

Figure 2.2: Plane motion model of fire truck
Table 2.1. Symbols for centroids, masses, initial coordinates and
coordinates at time t of the blocks
Moment of inertia about an axis parallel to and through the center of gravity
of the rotating blocks:Suspension IG ,later IGr , cluster under front fork IGf .
Let the outer radius of the rear and front wheels be Rr and Rf.
If in the coordinate plane O1xz, the road surface has the equation z = f(x) and
rear wheel axle R, front wheel axle F have coordinates of

( xR ,zR )and


( xF ,zF ) then the symbol dr =zR – f(xR) - Rr and df =zF – f(xF) – Rf (Figure
2.2). The pavement equation Z = f(x) is used in the calculation, in case the
pavement has a slope of α, the pavement equation will be:Z=X.tanα.
The physical meaning of the quantities dr , df:
+ Is the deformation of the rear and front tires (in the direction of
the wheel radius) if they are negative;
+ Is the distance from the road surface to the outside of the rear
and front tires if they have a non-negative value.
Thus, the front wheel is in contact with the road surface when the quantity df
is negative.
2.2.4. Equation of motion of a fire engine on a straight line
Lagrange function: L = T - П , and

q  





z z
G

T

is the general lagrang

F

coordinates, resulting in a system of equations of motion:
d  T 
T  Wd
i
dt q  Q  q  q q
 i
i
i
i

(2.37)

Substituting the expressions (2.18)-(2.36) into (2.37) leads to a system of
equations of motion of the form:

M q, q.q  P q,

(2.38)

q
By notation as above, the matrix M and P have the form:
 A11


A1

A1

2

3

A14 


 T  Wd



QV





1



;




A21 A22 A23 A24 ;
M 


 A31 A32 A33 A34


A A A A
 41 42 43 44 



P
1





T





 W


d  Q  V







(2.39)





2 
  
P2

P   

P 
 T  Wd
V
Q



z
3
 P3 
z
z
 z
G
G
G

 4


 T    Wd  Q  V
z
z
z
4
G

q

z
G
 z F 

F



z
F

F

F



The system of differential equations (2.38) will be approximated by the

Runge-Kutta method and performed on Matlab. From the received values
z , x will be calculated d  z  f  x   z0 . The front tire grips
the
F

F

f

F

F

F

road surface if df < 0 , the case of the car loading head when d f  0 .


2.3. The balance of the vehicle when moving straight and rounding, the
kinematic equation of the motorcycle when moving through small
square corners
2.3.1. Balance of motorcycle when moving straight
The balance of the motorcycle when moving straight is basically due to a
combination of two factors: driving the front wheel and shifting the driver's
center of gravity with the aim to bring the vehicle's center of gravity
(including the driver) and the contact point. Tire contact with the road is on
the same vertical plane. This can be described in Figure 2.3.

Figure 2.3: Balanced model of the vehicle when moving in a straight line

A1, A2 – driver's center of gravity; G1, G2 – center of gravity of the vehicle;
B1, B2 tire contact point and road surface ; MN - vertical line.
In Figure 2.3, models (a) and (b) represent the driver's center of gravity at the
same height and the vehicle with the same tilt angle α. To put the points A i,
Bi, Gi (i = 1,2) on the same line MN, the line segment A 1M is smaller than the
line segment A2M, that is, in model (a) the driver's center of gravity shifts
less than in the model. figure (b); At the same time, we also see more rudder
tire displacement in model (a) right than in model (b). Thus, a vehicle with a
higher center of gravity will make it easier to drive when the vehicle has a
low center of gravity (because it has to move the driver's center of gravity to
the side less).
Consider the driver model depicted in Figure 2.3. Neglect rolling resistance
(FW=0) and lift force (FL=0). There are the following forces acting on the
motorcycle: weight mg and air resistance F D acting at the vehicle's center of
gravity G; thrust FR exerted by the road surface on the motorcycle at the point


of contact with the rear wheel; vertical reaction N f and Nr between the road
plane and the front and rear tires.
Let the height of the vehicle's center of gravity be h, the vehicle wheelbase p,
and the horizontal distance from the vehicle's center of gravity to the rear
wheel's ground contact point b. From the equilibrium conditions of force and
moment we have:
+ Balance of horizontal forces: FR – FD = 0
(2.40)
+ Balance of vertical forces: mg – Nr – Nf = 0

(2.41)

+ Equilibrium of moments with respect to the center of gravity:

FR.h – Nr.b + Nf (p − b) = 0

(2.42)

Figure 2.4: The force acting on the motorcycle when moving in a
straight line
From (2.41) and (2.42) we get:
(2.43)
b
h
Dynamic load on front wheel: N  mg  F
f

Dynamic load on rear wheel:

N  mg
r

p
( p  b)
p

R

p

F
R

h

(2.44)

p

Thus, if the vehicle's center of gravity is higher (h increases), the dynamic
load on the front wheels will be reduced, leading to a decrease in traction of
the front wheels. Therefore, through the actual design of motorcycles, the
ratio between the height of the center of gravity and the wheelbase in
motorcycles

h
p

usually in the range of 0.3 - 0.45. [61].

2.3.2. The speed of the motorcycle when making a turn
a) Ideal speed and angle of inclination when the vehicle turns around


To study the speed and angle of inclination when the vehicle is making a
turn, the following assumptions are made (Figure 2.4).
Called µ the coefficient of sliding friction between the tire and the road
surface, then the sum of the horizontal sliding friction between the tire and
the road surface is:

Fms  .Nf  .Nr  .N 
.mg

(2.45 a)

Call the horizontal forces acting horizontally at the contact points with the
road surface of the front and rear tires as Fsf and Fsr and the sum of these
two forces is Fs, we have
Fs = Fsf + Fsr
(2.45 b)
Let the vehicle speed be V and the radius of rotation Rc (distance from the
center of gravity to the axis of rotation), the angle of inclination of the
vehicle with the vertical is φ.
It is possible to describe the balance of the vehicle according to the figure 2.5
From the balance of the vehicle leads to :
2

mg.tan  m    arctan v2
vR
c
gR

(2.46)

c

Figure 2.5: The angle of inclination of the motorcycle when turning around
with the assumption of tires zero thickness
Thus, in the ideal case when the car
moves
around a curve of radius R c, the
gR
c
vehicle speed must satisfy:

v

(2.48)

b) The angle of inclination when the car turns around
Assume that the motorcycle has a tire thickness of 2t, the car turns around
with a turning radius Rc and a speed v. Since the thickness of the tire is nonzero, from the equilibrium condition of the moment due to the weight and


the centrifugal force, the tilt angle φ is larger than the ideal angle φ i (Figure
2.6):

  i  

(2.49)

Figure 2.6: Tire angle when turning around with a tire thickness of 2t
According to the description in figure (2.6), we get:


v2  
(2.51)
      arctan

v2

t .sincarctan

g

 arcsin

ht R

i

gR

c









Equation(2.51)shows that Δφ increases as the cross-sectional radius increases
and as the height of the center of gravity h decreases. Therefore, the use of
wide tires forces the rider to make a larger incline than when riding a
motorcycle with a smaller cross-sectional tire. Furthermore, with equal crosssections of the tires, to move the same turn at the same speed, a motorcycle
with a low center of gravity needs to lean more than a motorcycle with a
higher center of gravity.
2.3.3 Kinematic equations of motorcycles when moving through narrow
square corners
To study this content, we have several types of right angles in Figure 2.6.

Figure 2.7: Some types of right angles

Assume that the plane projection of the vehicle (including the mounted
equipment assembly) is rectangular with width R and length L. Notice that,
with the cornering patterns as shown in Figure 2.7, if the vehicle moves If
you can pass the corner of form (c), you will be able to move through the
corners in the remaining forms.
Therefore, we only set up the kinematic equation of the projection plane by
the vehicle moving through the corner of shape 2.7 (c) described in figure
2.8.

Figure 2.8: Kinematic model of the vehicle moving through a right angle

(a)- Square corner ; (b) Plane view of the vehicle;
(c) Flat projection when the vehicle turns a corner
From the figure 2.8(c), it can be seen that the car can move through the
corner if the side AB moves through the corner. Side AB is longest when it
touches the circle with center O1 and radius R. Therefore, in order for the car
to move through the corner, the length AB must be equal to the shortest
segment of this tangent that is blocked by the two corners of the corner.
From the above kinematic model, we lead to the following problem:
Given 1/4 circle with center O1(a,b) and radius R satisfying the
conditions: R < a and R < b (Figure 2.9). The line segment AB is the tangent
to this arc intercepted by the coordinate axes Ox and Oy. Find the minimum
value of AB when the point of contact M moves on this arc.

Figure 2.9: Mathematical model of the moving motorbike problem
through the square corner


The length of segment AB will be:

LAB 

(2.57)

R2  b( y1 b )  a(x 1 a ) 
x2 ba y2  R 
( y1  b )( x1  a )

Find the minimum value of LAB in terms of x1, y1 with the constraint:
 a  R  x1  a

b  R  2y1  b
( x  a )  ( y  b )2 
R2
 1
1

(2.58)

The calculation to find the minimum value of L AB = LABmin with constraints
(2.58) will be presented in the next chapter.
Thus, a motorbike with a projection plane equal to the width R and length
LABmin will be able to move through the corners between two lanes of width a
and b.
2.4. Model for calculating the maximum horizontal deflection of the
instrument cluster
In order to describe the motion of the driver when moving in a straight line in
the case of a horizontal deflection of the center of gravity of the instrument
cluster, two degrees of freedom are considered according to the diagram of
figure 2.10. The first degree of freedom is the horizontal displacement of the

rider's lower body relative to the motorcycle and it is simulated by the
horizontal displacement of point B (which is the point of the rider's pelvis)
relative to the fixed point A on the vehicle. . The second degree of freedom is
the upper body inclination simulated by the angle θr.

Figure 2.10: Description of the driver's state when the vehicle is moving
straight in case the center of gravity of the instrument cluster has a
horizontal deflection


Symbols in Figure 2.10: θr - The angle of inclination of the upper body; Gm
– Center of the instrument cluster; Gt - Center of gravity of the upper body;
ym and yn – Horizontal deflection distance of G m and Gn; Pm and Pn – Unit
weight and body weight;
yr - Horizontal displacement of the rider's lower body relative to the
motorcycle.
Let Ln = BGt be the distance between B and Gt. Since the rider must lean to
the opposite side of the center of gravity Gm, we have:

yn  Ln sinr  yr

(2.59)

From the moment equilibrium condition leads to: yn Pn  ym Pm (2.60)
From there get:

Pn Ln sinr 
y
yr 
m

Pm

(2.61)

Thus, the maximum horizontal deflection distance of Gm to match the driver's
comfort when knowing the changing region of the parameter pair (θ r, yr)
(since Pn, Pm and Ln are known). The determination of the variable region of
the parameter pair (θr, yr) through experiment will be presented in chapter 4.
Chapter 3
SURVEY OF THE FIRE FIRE MOTORCYCLE EQUATION
On the basis of the results obtained in chapter 2, the thesis conducts a survey
of the established systems of dynamic equations (2.38), the survey results
serve as a scientific basis for determining the reasonable value of a Parameter
numbers for fire fighting motorcycles.
3.1. Investigation of the kinematic equation of planar motion of fire
engines
3.1.1. Determining the input parameters for the survey problem of
linear motion of fire engines
In the established system of equations (2.38), there are many geometrical,
kinetic, and dynamical parameters, so in order to investigate the dynamic
equations set up above, it is necessary to determine the values of these


parameters. The results of determining the input parameters for the
theoretical survey problem are recorded in Table 3.1.


Table 3.1. Input parameters to investigate the linear motion dynamics
equation of fire fighting motorcycle - Kawasaki W175 SE

3.1.3. Survey results of kinetic equations of linear motion of fire engines
Survey when the vehicle is running on flat roads and on roads with ledges.
The bumpy height of the pavement is represented by the function z = f(x).
1



 2 (x  L0 )


(3.7)
f (x) 



2

H 1  cos


L



khi L0  x  L0  L








0




khi x  L , L  L  x
0

0

Here, H=0,3 (m) is the height of the bumper, L =0,5 (m), L0 = 20 (m), (Figure
3.2). Evaluate the phenomenon of vehicle loading (the front wheel is not in
contact with the road surface) through the quantity d f = zF – f(xF) - RF, where
(xF,zF) is the coordinate of the front wheel axis and R F is the outer radius. of
the front tire. The front tire grips the road when d f < 0 and does not contact
the road when df ≥ 0. Note that, there is always df ≥ -hb where hb is the
maximum deformation of the front tire, in the calculation here take h b = 0.02
(m).

Figure 3.1: Description of road surface bump in length
The survey problem with two ways to change the speed of the rear wheel of
the vehicle is described in Figure 3.2 as:


The law of linear speed change of the wheel is:

vR 

25
18

t , ( m / s ) (3.8)

The law of nonlinear velocity change (i.e. acceleration varies with time),
505 
expressing velocity has the form:

 t 1 15 1 ,( m / (3.9)
v
s)

R

18 



Figure 3.2: Describe two ways of changing vehicle speed over time
Line 1: Law of linear velocity change equation (3.8)
Line 2: Nonlinear velocity change law equation (3.9)
a) Survey with the law of speed change and the vehicle through the
bumpy road surface
Survey with the mass of equipment cluster mM = 90kg on two types of flat
roads without obstacles and with burrs with two ways of changing the speed
(1), (2) in Figure 3.3, when the xM value changes gave the following df
value:

Figure 3.3: Graph df corresponding to speed according to the rule (3.8)
without obstacles: f(x) = 0



Figure 3.4: Graph df corresponding to the speed according to the rule
(3.9) without obstacles: f(x) = 0

Figure 3.5: The graph of df corresponding to the speed according to the
rule (3.8) has a barrier : f(x) > 0

Figure 3.6: The graph of df corresponding to the speed according to the
rule (3.9) has a barrier : f(x) > 0
From the survey results obtained in Figures 3.3 to Figure 3.6, the following
observations are made:
1. There are no barriers on the road surface in the graphs of Figure 3.3 and
Figure 3.4
+ The vehicle's ability to grip the road is reduced when the xM value is
smaller (ie, the closer the vehicle cluster is installed to the rear).
+ With the way to change the speed according to the rule (3.8) (road (1)
figure
3.2 gives better ability to grip the road than the way to change the speed
according to the rule (3.9) (road (2) figure 3.2. the law of speed change (3.8),
the car clings to the road surface at all speeds when xM ≥ 0 (figure 3.3), but
with the law of speed change (3.9) with xM = 0, the front wheel does not stick
to the road when vehicle at speed v > 50km/h (Figure 3.4).
2. On a bumpy road with a height of 30cm and a width of 0.5m (Figure
3.1), all vehicles pass at a speed greater than 25km/h (Figure 3.5 - Figure
3.6).