Chassis Control based on Fuzzy Logic

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HAL Id: hal-01309614 https://hal.archives-ouvertes.fr/hal-01309614 Submitted on 29 Apr 2016 HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Chassis Control based on Fuzzy Logic Carlos Albertos Vivas Lopez, Ruben Morales-Menendez, Ricardo Ramirez-Mendoza, Olivier Sename, Luc Dugard To cite this version: Carlos Albertos Vivas Lopez, Ruben Morales-Menendez, Ricardo Ramirez-Mendoza, Olivier Sename, Luc Dugard. Chassis Control based on Fuzzy Logic. IEEE International Conference on Fuzzy Systems (FUZZ-IEEE 2016) / IEEE World Congress on Computational Intelligence (WCCI 2016), Jul 2016, Vancouver, Canada. hal-01309614

Transcript of Chassis Control based on Fuzzy Logic

Page 1: Chassis Control based on Fuzzy Logic

HAL Id: hal-01309614https://hal.archives-ouvertes.fr/hal-01309614

Submitted on 29 Apr 2016

HAL is a multi-disciplinary open accessarchive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come fromteaching and research institutions in France orabroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, estdestinée au dépôt et à la diffusion de documentsscientifiques de niveau recherche, publiés ou non,émanant des établissements d’enseignement et derecherche français ou étrangers, des laboratoirespublics ou privés.

Chassis Control based on Fuzzy LogicCarlos Albertos Vivas Lopez, Ruben Morales-Menendez, Ricardo

Ramirez-Mendoza, Olivier Sename, Luc Dugard

To cite this version:Carlos Albertos Vivas Lopez, Ruben Morales-Menendez, Ricardo Ramirez-Mendoza, Olivier Sename,Luc Dugard. Chassis Control based on Fuzzy Logic. IEEE International Conference on Fuzzy Systems(FUZZ-IEEE 2016) / IEEE World Congress on Computational Intelligence (WCCI 2016), Jul 2016,Vancouver, Canada. �hal-01309614�

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Chassis Control based on Fuzzy LogicCarlos Alberto Vivas-Lopez, Ruben Morales-Menendez, Ricardo Ramirez-Mendoza

Tecnologico de MonterreySchool of Engineering and Sciences

64,849 Monterrey, Nuevo Leon, MexicoEmail: { A00794204, rmm, ricardo.ramirez }@itesm.mx

Olivier Sename, Luc DugardGIPSA-lab / Control System Department

Grenoble Institute of Technology38,402 Saint Martin d’Heres Cedex, France

Email: { olivier.sename, luc.dugard@}@gipsa-lab.grenoble-inp.fr

Abstract—Based on a Global Chassis Control system withthree-layers architecture (decision, control, and physical layers)a Fuzzy Logic (FL) approach is exploited. The FL based decisionlayer identifies the current driving condition of the vehicle anddecides the control strategy to take care of this driving condition.A confusion matrix validates the classification results. The controlstrategy is implemented through the subsystems (suspension,steering, and braking) at the FL based control layer. The strategywas evaluated under two different tests: slalom and double linechange by comparing the performance with an UnControlledsystem. Early results show the proposed strategy has less roll,yaw movement and side slip angle than an UnControlled systemduring a double line change maneuver; also, for the slalom testthe proposal improves the dynamic vehicle performance allowingthe driver to maintain the vehicle under control.

I. INTRODUCTION

The internal combustion engine has powered cars, trucksand other vehicles for over a century. Hybrid electric vehicles,plug-in hybrid electric vehicles, pure electric vehicles, andother technologies can all be properly classified as Next-Generation Vehicles (NGV). Certainly, reduce oil consump-tion is one of the main features of NGV; but, reducingoil consumption reduces pollution too, [1]. The technologyareas supporting NVG are (a) Electric vehicle system: elec-tric, hybrid and fuel cell vehicles; (b) Advanced vehiclemotion performance: active control, drive assistance, preven-tive safety; (c) Smart structure: light-weight/highly, efficientstructure, collision safe; and, (d) Intelligence: car electron-ics/control/information/communication. The cost of electron-ics and software content in automobiles was less than 20 %of the total cost a decade ago, today is ∼ 35 %. Electronicssystems continue to contribute more than 90 % of innovationsand new features, [2].

Intelligence for vehicles is the technology that shouldbe related to almost all automotive technologies; however,especially in the active control area aiming at preventionand safety. Significant advances have been made in recentyears in chassis control systems. Various control systems havebeen developed with the aim of enhancing vehicle dynamicperformance; such as, Vehicle Control Systems (VCS) include

Anti-lock Brake Systems (ABS), Electronic Stability Control(ESC), Electric Power Steering (EPS), Active Suspension,and variable torque distribution four-Wheel Drive (4WD).Coordinated and integrated controls play an indispensable roleamong these systems, [3]. An Integrated Vehicle DynamicsControl considers the coordinated integration of those differentVCS to pursuit a common goal. Many approaches for GlobalChassis Control (GChC) have already been developed, [4].

It is seen that a main issue is the number of possibilitiesto affect the motion of the vehicle, based on the actuatorsconfiguration. In [4], [5] a GChC system is implemented witha supervisory decentralized control architecture (for flexibilityand modularity). First, the system classifies the current drivingcondition using a clustering-based classifier [6]. Second, eachsubsystem is coordinated to ensure the best possible globalperformance. The subsystems are: Semi Active Suspension(SAS), Active Front Steering (AFS) and 4-Wheel IndependentBraking (4WIB). These subsystems work simultaneously look-ing for three main goals: stability, handling and comfort. Basedon this GChC system a new Fuzzy Logic (FL) based classifieris proposed.

This paper is organized as follows. Section II briefly intro-duces the GChC system. Section III describes in detail the FLbased classifier. Section IV presents FL based controllers. Astudy case validates the results in section V. Finally, sectionVI concludes the research paper.

II. GLOBAL CHASSIS CONTROL SYSTEM

The architecture of the Global Chassis Control (GChC)system, Fig. 1, considers three main layers: Decision, Controland Physical [4].

A. Decision layer

This GChC system coordinates the mode of operation ofthe control subsystems based on the actual driving conditionof the vehicle. For this purpose, two main functions are carriedon: classify the driving condition and coordinate the controlstrategy for the current driving condition.

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Control Layer

Suspension Control

Active Front Steering Control

Electronic Stability Control

Decision Layer

Physical Layer

Output System

Input System

Semi-Active Suspension

Active Front Sterring

Braking system

Sensors

Decision Logic

FL based Suspension Adjusment Plane

FL based

Classifier

Fig. 1. GChC system

The classification procedure is carried out using a FuzzyInference System (FIS), it classifies the current situation basedon measurements only. To assist the classifier a Fuzzy logicSuspension Adjustment Plane (FSAP) is included. It adjuststhe suspension system based on the vertical load transfer ofthe vehicle.

B. Control layer

In this layer there are FL based controllers for the actuationsubsystems located in the physical layer. This layer has twomain functions: control allocation and local controllers. Thecontrol allocation step computes the desired manipulationusing the adaptable set point defined in the decision layer,such allocation is calculated using FL algorithms. The localcontrollers execute the needed controller output.

C. Physical layer

The physical layer is integrated by the sensors and actuatorsof the SA suspension system, AFS system and the 4-WheelIndependent Braking system.

III. DECISION LAYER

The main task of the Decision Layer (DL) is to adapt thecontrol actions of the vehicle subsystems using the vehicledriving condition as the coordination parameter. Seven DrivingConditions (DC) were considered: 1) Riding, 2) Road irregu-larity, 3) Acceleration/Braking, 4) Hard braking, 5) Cornering,6) Rapid Steering, and 7) Loss of control.

For each DC there is a set of actuation gains (au) thatcoordinates the operation of the actuation subsystems: aususp

for the suspension system, austeerfor the steering system, and

TABLE IDC VECTORS FOR DIFFERENT DRIVING CONDITIONS.

Driving situation DC

si aususp austeer aubraking

Ride 1 [0,0,0,0] 0 0Road irregularity 2 FSAP 0 0Acceleration/Braking 3 FSAP 0 0Hard Braking 4 FSAP 0 0Cornering 5 FSAP 1 0Rapid Steering 6 FSAP 1 1Loss of control 7 [1,1,1,1] 1 1

aubrakingfor the braking. The coordination for each DC is

described in Table I.The system needs the current driving condition of the

vehicle. A FIS is proposed to classify the driving conditionbased on 4 operating variables: pitch angle (ϕ ∈ [−2, 2]),absolute value of yaw rate (|ψ| ∈ [0, 100]), and the absolutevalues of the steering wheel angle and steering wheel anglerate (|δ| ∈ [0, 20], and |δ| ∈ [0, 100]).

As inputs of the system consider three of the operatingvariables were fuzzified using two trapezoidal MembershipFunctions (MFs): {|ψ|, |δ|, |δ|} = {Z,P} and for the lastoperating variable 4 triangular and 2 trapezoidal MFs whereused as: ϕ = {NB,NS,Z, PS, PM,PB}.

As output, seven MF were used. Figure 2 shows the usedMF as I/O of the classifier. Table II describes the meaningsof the linguistic terms.

0 0.5 1 1.5

Pitch Angle

0

1

Deg

ree

of

mem

ber

ship

Z PS PM PB

NS

NB

0 20 40 60 80 100

0

1

Yaw Rate

Deg

ree

of

mem

ber

ship

Z P

0 1 2 3 4 5

0

1

Steering Wheel Angle

Deg

ree

of

mem

ber

ship

Z P

0 20 40 60 80 100

Steering Wheel Angle Rate

0

1

Deg

ree

of

mem

ber

ship

Z P

1 2 3 4 5 6 7Driving Condition

DC1

DC4 DC6DC2

DC3 DC5 DC70

1

Deg

ree

of

mem

ber

ship

(a) Inputs

(b) Output

Fig. 2. Classifier Membership Functions.

Table III shows the proposed linguistic rules for the classi-fier. The X, element is used as a wild card for simplicity andwith the intention of save space to avoid repeating rules.

The performance of the proposed classifier was qualitativelyevaluated through a series of tests. Figure 3 shows the resultsof the evaluation. The first test, Fig. 3a, is a rough road with abump that appears around 1 s, the classifier identifies the bump

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TABLE IILINGUISTIC TERMS.

N Negative PS Positive SmallNB Negative Big PMS Positive Medium SmallNMH Negative Medium High PM Positive MediumNM Negative Medium PMH Positive Medium HighNMS Negative Medium Small PB Positive BigNS Negative Small P PositiveZ Zero

TABLE IIIFUZZY INFERENCE RULES FOR THE CLASSIFIER

Inputs Outputϕ ψ δ δ

Z Z Z Z DC1NS Z Z Z DC2PS Z Z Z DC2NB Z Z Z DC3PM Z Z Z DC3PB Z Z Z DC4X Z P Z DC5X Z X P DC6X P X X DC7

but the generated oscillations by the transient response of thevehicle causes some misclassification. For the second test Fig.3b shows a braking distance test, representing a hard brakingaction at the beginning followed by a normal braking untilstop, the classifier also performs well, but the misclassificationwere caused by the oscillatory movement. For the third testFig. 3c presents a rapid steering maneuver; whereas the fourthtest Fig. 3d consists in a sustained turning action. Finally, forthe fifth test, Fig. 3e shows a raking maneuver in a slipperyroad, which causes the vehicle to spin without control.

To visualize of the performance and summarize the evalu-ation of the FL based classifier, the Confusion Matrix (ErrorMatrix) was computed in Fig. 4, [7]. It can be seen that, theclassifier has a good performance. For most of the drivingconditions present more than 80 % of classification probability,with less than 15 % of false alarms probability. These resultsgive an 85 % of average performance for the classifier.

Finally, a Fuzzy logic Suspension Adjustment Plane (FSAP)is proposed into the Decision Layer. This plane is based inthe load transfer of the vehicle caused by the vehicle verticalforward and lateral movements. It allocates the control actionsof the SA dampers in the suspension system. Figure 5 showsthe regions of the FSAP with the proposed output vector foraususp in each region. The vector is formed as: aususp =[FrontLeft (FL), Front Right (FR), Rear Left (RL), Rear Right (RR)].

The proposed FIS for the FSAP uses 2 inputs: roll angle(θ ∈ [−5, 5]) and pitch angle (ϕ ∈ [−1, 3]). The output isformed by 4 elements:(aususpi,j

∈ [0, 1]), where aususpi,jis

the weighting parameter for each corner of the vehicle. For thetwo inputs, 3 triangular Membership Functions (MF) whereused for each variables: {θ, ϕ} = {N,Z, P}. For the outputvariables 2 triangular MFs were used: aususpi,j

= {Z,P}.Table IV shows the linguistic rules that govern the FSAP.

This FL system is intended to adjust the control objective

0 0.4 0.8 1.2 1.6

Dc=1

Dc=2

Time [s]

0 1 2 3 4 5

Dc=1

Dc=3

Dc=4

Real driving

condition

Estimated

driving

condition

0 1 2 3 4 5 6

Dc=1

Dc=5Dc=6

0 2 4 6 8 10Dc=1

Dc=5

Dc=6

0 1 2 3 4 5 6 7

Dc=1

Dc=6Dc=7

(a)

(b)

(c)

(d)

(e)

Fig. 3. Evaluation of the FL based classifier. Comparison of real (dashedblue) and estimated (solid red) driving condition.

TABLE IVFUZZY INFERENCE RULES FOR THE FSAP.

Roll angle (θ)N Z P

aususp L R L R L R

Pitc

han

gle

(ϕ)

P F P P P P P PR P Z Z Z Z P

Z F P Z Z Z Z PR P Z Z Z Z P

N F P Z Z Z Z PR P Z P P Z P

of each damper of the SAS, i.e. if the vehicle has a sufficientroll movement to the right, then the two dampers of that sidemust be oriented to road holding mode to compensate theincreased vertical force generated by the roll movement. Theimplementation of a FIS guarantees a smooth and continuoustransition between the heuristic controllers of the SAS systemavoiding abrupt switching behavior.

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Dc1 Dc2 Dc3 Dc4 Dc5 Dc6 Dc7

Dc1

Dc2

Dc3

Dc4

Dc5

Dc6

Dc7

876127.7%

2300.7%

450.1%

80.0%

820.3%

2750.9%

00.0%

93.2%

6.8%

750.2%

2090.7%

00.0%

00.0%

00.0%

00.0%

00.0%

73.6%

26.4%

00.0%

00.0%

18405.8%

600.2%

00.0%

00.0%

00.0%

96.8%

3.2%

130.0%

1120.4%

5561.8%

11443.6%

00.0%

00.0%

00.0%

62.7%

37.3%

1050.3%

00.0%

00.0%

00.0%

678321.5%

21106.7%

00.0%

75.4%

24.6%

00.0%

00.0%

00.0%

00.0%

7922.5%

21926.9%

00.0%

73.5%

26.5%

00.0%

00.0%

00.0%

00.0%

00.0%

00.0%

622819.7%

100%

0.0%

97.8%

2.2%

37.9%

62.1%

75.4%

24.6%

94.4%

5.6%

88.6%

11.4%

47.9%

52.1%

100%

0.0%

85.9%

14.1%

Actual Driving Situation

Cla

ssi!

ed

Dri

vin

g S

itu

ati

on

Fig. 4. Confusion matrix for the classifier.

Roll Angle

Pit

ch A

ng

le [1,1,0,0]

[0,0,1,1]

[0,1,0,1][1,0,1,0]

[1,1,0,1][1,1,1,0]

Z PN

P

N

Z [0,0,0,0]

[0,1,0,1][1,0,1,0]

Fig. 5. FSAP diagram showing the proposed output vector for aususp .

IV. CONTROL LAYER

This layer comprehends the control actions (allocation,manipulation) to be implemented through the physical layer.

A. Control Allocation

Based on the driving situation, the desired control action foreach subsystem is defined. The control mode acts as a gain:

u∗c = au · uc (1)

where u∗c is the controller output which depends directly fromthe gain au, where au = 1 means that the GChC demandsthe actuation of the subsystem, and vice versa. Thus, uc isthe local controller output of the subsystem, but before thefull dynamics integration. The allocation controllers for eachsubsystems are defined as follows.

1) Semi-Active Suspension System: The SA dampers mustalways receive a manipulation, the decision is whether toselect a manipulation oriented to comfort (U |comf ) or to road-holding (U |rh) for each corner of the vehicle:

U∗susp = (1− aususp

) · U |comf + aususp· U |rh (2)

where U∗susp = ususpF,L

, ususpF,R, ususpR,L

, ususpR,R.

Note that, according to the driving situation, the GChC canorient the suspension to comfort or to road-holding using theweighting parameter aususp .

At each corner, the Semi-Active Suspension controller out-put can be oriented to comfort (ui,j |comf ) or to road-holding(ui,j |rh) inspired in the classical Sky-Hook and Ground-Hookcontrol strategies, such that:

ui,j |rh =

{cmin if −zus · zdef ≤ 0cmax if −zus · zdef > 0

(3)

ui,j |comf =

{cmin if zs · zdef ≤ 0cmax if zs · zdef > 0

(4)

where cmin = 0 and cmax = 1 represent the softest andhardest damping coefficient, respectively.

2) Braking System: The braking action is determined basedon a FL based controller, [8]. It uses two inputs: the side slipangle error (e(β) = β − βd) and the yaw rate error (e(ψ) =ψ−ψd) and one output: the corrective yaw moment (Mz). Thecontrol goal is to reduce the errors to zero; for this purpose thereference signals are defined as βd = 0, since the goal is tohave β as close to zero as possible and ψd = Vx

l δdriver whereVx is the longitudinal velocity of the vehicle, l is the wheelbase and δdriver is the drivers steering angle command. TableV shows the rules for the proposed FL controller. This fuzzycontroller uses a Mandani Fuzzy Inference System (FIS).

TABLE VFUZZY INFERENCE RULES FOR THE BRAKING SYSTEM

e(β)e(ψ)

NB NS Z PS PBNB PB PB NS NB NBNS PB PM NS NM NBZ PM PS Z NS NM

PS PB PM PS NM NBPB PB PS PS NS NB

To allocate the desired output for the braking local con-trollers, Mz is transformed in terms of ESCs as

Mz > 0 → Brake rear left wheel :TESCr = 0, TESCl

= TG ·Mz

Mz = 0 → Noadded brakingTESCr = 0, TESCl

= 0Mz < 0 → Brake rear rightwheel

TESCr = −TG ·Mz, TESCl= 0

(5)

where TG is a parameter that relates the corrective yaw mo-ment (Mz) and the brake pressure. The coordinated allocationaffects the action of the FL based controller, by using aubraking

as a gain:T ∗ESC = aubraking

· TESC (6)

3) Active Front Steering System: The allocation introducesthe AFS control action:

δ∗ = δdriver + austeer · δAFS (7)

where δ∗ is the desired steering wheel angle, δdriver isthe driver’s command, and δAFS is the compensation angle

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calculated by the AFS system. The steering action is computedusing a FL based controller, [9] with three input variables: sideslip angle (β ∈ [−10, 10]), the yaw rate error (e(ψ) = ψ−ψd ∈[−10, 10]) and the steering angle input (δdriver ∈ [−10, 10]).

The output is the steering wheel correction angle (δAFS ∈[−5, 5]). The FL based controller is oriented to create asteering wheel angle correction that minimizes the yaw rateerror. Table VI shows the rules for the proposed FL controller,whose linguistic definitions are given in Table II.

TABLE VIFUZZY INFERENCE RULES FOR THE STEERING SYSTEM

β δdrivere(ψ)

NB NS Z PS PB

Low

NB NS NS Z PB PBNS NMS NMS Z PMH PMHZ NM NM Z PM PM

PS NMH NMH Z PMS PMSPB NH NH Z PS PS

High

NB NH NH Z PS PSNS NMH NMH Z PMS PMSZ NM NM NS PMS PMS

PS NMS NMS NS NS NSPB NS NS NS NS NS

B. Local Controllers

These controllers receive the desired set-point u∗c from thecontrol allocation sublayer, the subsystem controllers are:

• SA Suspension: because the control command is binary,the force control system is:[

cmin

cmax

]=

[01

]7→ υ =

[10%90%

](8)

where υ is the manipulation delivered to the SA damper,(i.e. electric current, voltage, duty cycle, etc.)

• Steering: the command is in terms of tire angles, totransform it to a single gain controller:

δ∗steering wheel =28.74

1.18δ∗tires (9)

• Braking: the local controller is an ABS, it modifies thedesired command as:

T ∗b = GABS ·max(Tdriver, T ∗

ESC) (10)

where Tdriver is the driver braking command, TESC isthe braking command from the allocation system andGABS is the gain of the ABS that releases the tire whenit is locked. This control law considers the maximumbetween the command coming from the allocation systemand the command from the driver.

V. CASE STUDY

For the case study the proposed GChC system was evaluatedusing the standard CarSimTM, along with MatLabTM in aSoftware-in-the-Loop (SiL) configuration; the vehicle modeland tests were hosted in CarSim, while the GChC system wasdeveloped in Matlab.

A. Vehicle Model

The selected vehicle is a D-segment sedan. According tothe European Commission, this segment includes vehicles inthe medium to high range (large cars). Table VII shows somegeneral parameters of the model.

TABLE VIICarSim GENERIC D-SEGMENT MODEL PARAMETERS [10]

Parameter Value Units Parameter Value Unitsms 1370 kg Ixx 671.3 km-m2

musi,j 40 kg Iyy 1972.8 km-m2

L 2.78 m Izz 2315.3 km-m2

b 1.11 m ksf 153 N/mmh 0.52 m ksr 82 N/mm

tf , tr 1.55 m kt 268 N/mm

B. Evaluation Tests

Two tests were implemented to evaluate the proposed GChCsystem, Fig. 6 illustrates these tests:

• Double Line Change (DLC) maneuver. It consists in achange of driving line to simulate an obstacle avoidancemaneuver or an overtaking action at high speed (120km/h). A rapid steering maneuver is taken by the driverto change from the original line, and then another rapidsteering action to turn back to the original line.

• Slalom test. This test evaluates how fast the vehicle candrive through the obstacles in a zigzag movement withouttouching them and not loosing control. It consists ina series of cones that the vehicle has to evade as fastas possible, this test forces the vehicle to its limits ofadhesion and maneuverability.

C. Performance Indexes

The proposed GChC system is evaluated and compared withan UnControlled (UC) system, i.e. it is a vehicle which lacksof any control system and that it is equipped with standardactuators and a passive suspension system. To quantitativelyevaluate the performance at each driving test, the Root MeanSquare (RMS) value of the signals is used. To have a pointof comparison, the RMS values of the GChC system will benormalized with respect to the UC system:

%of Imp =RMS(XiUC )−RMS(XiGChC

)

RMS(XiUC)

(11)

where % of Imp is the percentage of improvement, XiUC andXiGChC

are the variables of interest i of the UC and the GChCsystems respectively. The objective of this index is to showhow much the control system improves the behavior of thevehicle in terms of the variables of interest, giving the samedriver model, a topic which is not addressed in this work.

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5 m

5 m

18 m

126 m

4 m

10 m

30 m 30 m

a) DLC Maneuver

DLC Maneuver (CarSim)

Slalom Test (CarSim)

b) Slalom Test

Fig. 6. Implemented tests in CarSimTM.

D. Results

The results are presented in terms of the variables of impor-tance for each test. Here the important variables to analyze are:1) vehicle trajectory, 2) θ 3) ψ, and 4) β. Figure 7 shows thetrajectory of both cases: UC (blue) and GChC (green). Figures8 and 9 show the behavior of the other variables of importancefor the DLC maneuverer and slalom test, respectively.

For a quantitative analysis Table VIII present the RMS valueof the important variables in terms of its % of improvement,calculated using (11).

TABLE VIIIPERFORMANCE INDICES FOR BOTH TESTS.

Test DLC Slalom

Variable θ ψ β θ ψ β% of Imp. 10 % 12.5 % 14.4 % 11.1 % 20.5 % 76 %

E. Discussion

1) DLC test: From Fig. 7a, it can be observed that theGChC system has smaller y-coordinate deviation, also its endis straight. For the UC system the y-coordinate deviation isbigger and at the end its path is diverging.

0 50 100 150 200 250−2−1

0

1

2

3

4

GChCUC

x-coordinate [m]

y-coordinate [m]

0 20 40 60 80 100 120 140−3

−2

−1

0

1

2

GChCUC

x-coordinate [m]

y-coordinate [m]

a) DLC test

b) Slalom test

Fig. 7. Vehicle trajectory for both DLC and Slalom tests.

Figure 8a illustrates the GChC has 10 % less roll movementthan the UC system, Table VIII, and also, the roll movementhas a rapid stabilization. In Fig. 8b the GChC system has12.5 % less yaw motion than the UC. In terms of the side slipangle, Fig. 8c shows the GChC system maintains the β angleclosest to zero as much as possible reducing it about 14.4 %compared to the UC system.

2) Slalom test: In Fig. 7b the UC system presents a slightlywider path than the GChC system, this causes the vehicle tobe less controllable. This can be seen at the end the trajectory,where the UC case seems to finish the track perpendicular tothe horizontal axis, contrary to the GChC system that recoversthe horizontal path.

Even when in the trajectory evaluation the advantage of theGChC system was not clear enough, analyzing the variablesof interest, it becomes evident. First the GChC reduces the rollmovements, Fig. 9a, in 11.1 % by maintaining the vehicle in anhorizontal position, Table VIII. In terms of the yaw rate, Fig.9b, the proposed control system has an improvement of 20.5% when compared with the UC system avoiding the vehicle toskid. Finally, the side slip angle, Fig. 9c, was improved in 76% maintaining it as close to zero as possible, whereas in theUC system, at the end of the test, the vehicle losses controland start to spin.

VI. CONCLUSIONS

A Fuzzy Logic (FL) based Global Chassis Control systemwas proposed. The system considers a three layer archi-tecture: Decision, Control and Physical. The FL frameworkwas exploited in the Decision Layer to classify the currentdriving condition. Also, it was implemented in the Control

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−2

−1

0

1

2

0 1 2 3 4 5 6 7

GChC

UC

Time [s]

Ro

ll [

deg

]

a) Roll angle

0 1 2 3 4 5 6 7−10

−6

−2

2

6GChC

UC

Time [s]

Yaw

[deg

]

b) Yaw angle

−1

0

1

2

3

0 1 2 3 4 5 6 7

GChCUC

Time [s]

Sid

e S

lip

An

gle

[d

eg]

c) Side slip angle

Fig. 8. DLC test results

Layer for the suspension, steering and braking control systems.In the Decision layer the FL systems gave the possibilityto use the a priory knowledge of the vehicle behavior toclassify the current driving situation without a model of thesystem, having an average performance of 85 % based on aConfussion Matrix analysis. In terms of the performance ofthe control system, two tests: double line change and slalom,were used for evaluation. The results demonstrated that theproposal improves the vertical dynamics in at least 10 %, andthe longitudinal ones, about 12.5 % as minimum,proving theability of the system to act in the three dynamic planes.

ACKNOWLEDGMENT

Authors thank Tecnologico de Monterrey and CONACyT fortheir partial support through the Automotive Consortium re-search chair and PCP 06/13 bilateral (Mexico-France) project.

REFERENCES

[1] K. Hansen and J. Berger, “Next Generation Vehicles: Opportunities andObstacles,” Bloomberg Law ReportsSustainable Energy, vol. 3, no. 11,pp. 1–7, 2010.

a) Roll angle

b) Yaw angle rate

c) Side slip angle

0 2 4 6 8−4

−2

0

2

4

GChCUC

Time [s]

Ro

ll [

deg

]

0 1 2 3 4 5 6 7 8−60−40

−20

020

40

6080

GChC

UC

Time [s]

Yaw

Rat

e [d

eg/s

]

−30

−20

−10

0

10

0 1 2 3 4 5 6 7 8

GChC

UC

Time [s]

Sid

e S

lip

An

gle

[d

eg]

Fig. 9. Slalom test results

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