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详细说明：这篇论文讲述了智能驾驶方向纵向控制算法，侧重与卡车类的纵向算法3 Upper Level Control Dosign
Modeling Control System Structure
Upper level control design uses sliding mode approach to
generate desired torque from inter-vehicle distance track
ing error and speed tracking error based on vehicle dy-
namics
To avoid confusion, it is assumed that the starting
poil
ehicle is the initial point which
set to O and the forward direction is positive for distance
(x-coordinate).(=, v, a)and (apre, Upre, apre)rep
the moving distance, speed and acceleration of current
vehicle and preceding vehicle respectively. Then
Coutrol
Upre "v
apre a
0, Epre(0)= Lpre >0
0,
0)=0
With this notation there hold
Fi
1
An error model for upper layer longitudinal control de-
2.1 Engine Driving Mode
SIRIl IS
Engine net output torque equation:
ve=apre mm rdrgTderaTtd+TsFahr+Fh+Mgh sin
net
xe(0)
v2(0)=0
lock
(21)
(31)
T T1
the de
ntcr-yehicle di
Then choose the sliding surface as
Static Kotwicki model [1] is an example of torque con
s=ve +hi(ae-l),k1>0
renter model for n-function
Notice the following relationships
From any sliding reachability condition 8=-y(8)[8, the
desired torque Idea can be solved out as
Te=()+k+r)+rTd+Tb+h+F,hr+Mghsne
九1
hr
t
4 Lower Level Control
Taro
Due to the built-in engine. cont roller, it is impossible to
directly access the fuel rate command. Instead pedal de
Longitudinal vehicle dynanics can be modelled as
Aection is used as input. FroIn upper level control, desired
peed and desire
orque are calculated as (vdes, ldees
Using the eigne mapping, the desired fuel percentage rate
i= IdTafnet-(rafrtd+Tb+Fahr+Frhr+Mglr sin 6)
ades is obtain
om a lookup
十T
IA1十
+ au+Mhr
the approach in [4]. This section emphasizes on brake
Fa=0.5 Ca PatT A v2
control
where Tb is modelled separately
4.1 Braking System
Braking system for automatic control is composed of
2.2 Other modes
three parts: Jake brake, pneumatic brake and transmis-
sion retarder. Each part has its own characteristics, To
1. Engine Braking Mode: Tnet =-Tjk
0, 2, 4. 6) understand these characteristics for braking system con-
corresponds to the cases when throt t ]e is released but trol strategy is the key factor for good performance of the
control system and safety
0, 2, 4, 6 cylinders are on respectively. i=0 is the engine The total braking torque on wheels are
braking effect as proposed in [8]
2. Transmission Retarder Mode: Tnet =0: Transmis
ion retarder is on and throttle is oFF
Tb+T+2,“≥809pm
(4.1)
Air Brake Mode: Tnet=o and Tb>0
+
<8UU[7m]
Proceedings of the American Control Conferenci
Denver, Colorado June 4-6.2003
4.1.1 Jake Brake
4.1.3 Transmission Retarder
It provides discrete and limited braking torque on dry. It provides continuous braking torque on driving whee
ing wheels with fast response. Its retarding force mainly with slow response and limited braking torque [2]. A
depends on engine speed. The engine braking cffect pr
model for transmission retarder is proposed as follows
posed in [6 is caused by the mismatch between engine
speed and wheel speed when throttle is released and
drive-lire is engaged. It is recognized that this effect
[-Ttr +s(Vrta(t- Ktr),wdr), t Ttro
can be considerer as a special case of lake Brake when Ttr
there is no valve is open. From this point of view, the
- [-Ttr +(rtd(t), wdr)1, teTro
braking torque on driving wheels provided by engine can
be modeled in a variable structure model as
(45)
1.0
tro
Tik_0, 0 cylinder on
①k2,2 cylinder on
4, 4 cylinda
Tiro- pure time delay parameter 1.5
j k-6,6 cylinder
Vrtd-voltage or transmission retarder pedal defection
(Vrid, wir)-a nonlinear function
∽ems-brk
It is noted that the pure time delay parameter kir is
time varying and it disappears after 1. 5]. This time
d
,≥800m
period is used for filling up the liquid into the retarder
chamb
Applied torque on wheel is calculated as
2,4,6
which is a generalization from the engine braking effect
in 6. The following relationship are obviously true
To deal with the time delay part in the model
s(Vrta(t-mtr) is approximated by its first order Tay
r series
T0<们
(Vrta(t-Atr)
4.1.2 Pneumatic brake
Vrla(t
T70
tic (air) brake
d la
braking torque on all wheels. Its responsc is slow, Pncu
(n(-)
matic brake model for control design was proposed as 6
td(p)= vrtd(2p
Thus
m(B+42m(-),.cei
(42)
td
(P+ Ab Papp(t-Tr)
release
which is replaced into(4.5 )as
To design the controller, one expends the applied brake
pressure Papp(t- Ta) and Papp(t-Tr)using Taylor series
ch as follows
Trtd +s(Vrid(t)
Tr
t< Tt
Papp(t - s Papp(t)-Papp (t) Ta
[-Ta+<(Vrt(t)},
Pp(t-Tr)≈Pavp(t)
(4.3)
for control design
which is replaced into(4.2) to obtain
4.1.4 Braking System Control Strategy
1-P+As(Papp (t)-Papp(t]Tall, activation Suppose the total desired braking torque on all wheels
P
a a variable structure braking system control strategy is
T -Po+As(Pap?(t)-Papp(t)r)I, release proposed as follows
(4. 4/6fTbrk-totol S T,_0, no pneumatic brake nor jake brake
essary but throttle is
To implenent iL, Parp (t)can be calculated fron If l]k_0< Tbrk-totat Tj k-
Pann(t) in real-lime by a difference inethod or an inte-
gral Ilter
r642)+m;40)=+.tba-T;k
Proceedings of the American Control Conference
39
Denver, Colorado June 4-6. 2003
L:Tk2≤ Turk total<1k4,
These equa
e integrated
Tb42)mr4)=7k!-1k
(dea)
-The exp
p(des)
lea/rad
Ir≤ Tork totl
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