mechatronics design of small electric vehicles; research - ijens

International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:13 No:01 23

1310701-5252-IJMME-IJENS © February 2013 IJENS I J E N S

Abstract-- This paper proposes mechatronics design of small

electric vehicles (SMEV), including Mechatronics design,

modeling, simulation and integration of accurate sub-systems

and overall system models. the proposed design and models can

be used to select, integrate, analyze and validate Mechatronics

deign process of SMEV and its sub-systems ; including

mechanical system, control system, components and electrical

energy, resulting in simplification, acceleration and increasing

accuracy of design. The proposed overall system model can be

modified to include any control strategy and/or any electric

machine (motor), where the motor and its associated driving

power circuit and /or controller can be replaced with different

motors and/or control strategy. The proposed model intended to

be used for research purposes as well as, for the application in

educational process. The proposed models were created and

verified using MATLAB simulink software.

.

Index Term— Mechatronics design, Electric vehicle, Electric

Motor, simulink function block model.

I. INTRODUCTION

Mechatronics systems design is Modern interdisciplinary

design procedure; it is a concurrent selection, evaluation,

integration, and optimization of the system and all its

components as a whole and concurrently, all the design

disciplines work in parallel and collaboratively throughout the

design and development process to produce an overall optimal

design. Mechatronics engineer is expected to design products

with synergy and integration toward constrains like higher

performance, speed, precision, efficiency, lower costs and

functionality, and in order to evaluate concepts generated

during the design process, without building and testing each

one, the mechatronics engineer, also, must be skilled in the

modeling, simulation, analysis, and control of dynamic systems

and understand the key issues in hardware implementation.

The Electric Vehicle, EV, was invented around middle of 19th

century. An EV uses one or more electric or traction motors for

propulsion and can be separated into three groups, based on

how and where the electricity is produced; powered from an

external power station, e.g. trolleybuses, powered by stored

electricity from an off-board generation system e.g. battery

electric vehicles and powered by an on-board electrical

generator such as an internal combustion engine (a hybrid

electric vehicle)[1] the last two groups are shown in Fig. 1. EV

can also be categorized into two groups; big and small electric

vehicles. In this paper we are most interested in design and

control of Small Mechatronics Electric Vehicles, SMEV.

Application examples of SMEV include; golf cars, power chairs

for the disabled, go-karts, home mobile robots, mobility

scooters, sea scooters and tiny quad bikes . A general model

that can be used to simplify and accelerate the mechatronics

design process of SMEV is desired. This paper suggests such

model, we are to develop general mathematical and simulink

models that can be applied in mechatronics design of SMEV,

considering all dynamics, with corresponding optimal control

strategy for desired output response, a general model that can

be used to design, select, integrate, test, analyze and control

SMEV to achieve desired performance.

The EV system consists of two subsystems, the electric motor

and the vehicle systems, the main components of the electric

vehicle (see Fig.1) are an electric machine as drive system,

electrical energy sources, control systems as a central control,

and power converter as a device that converts electrical energy

source with variable needs of the electric vehicle by switching

devices [2]. Meanwhile electric vehicles generally use a battery

as its main energy source [3],[4],[5]. But the batteries on

electric vehicles have a weakness that has the capacity and

service life is limited so that necessary arrangements for

charging batteries do not work hard [2].To drive EV system,

one electric motor can be used or two electric motor each for

each wheel, we will consider the case of one front drive electric

motor used.

The EV system takes input voltage as electric motor input, and

outputs the rotational speed of electric motor or the motion of

electric vehicles, electric motors are capable of generating high

torque at low speed, can operate efficiently over a greater

range of speeds, that is their speeds can be smoothly

controlled and in most cases are reversible, also electric motors

and their features can be tested and analyzed both by control

system design calculation and by MATLAB software, also by

using a simple controller e.g. of PIC micro, with corresponding

program and drive circuit, the rotation of electric motor, that is

the motion of electric vehicles can be controlled easily and

smoothly. The electric actuator most used for SMEV are DC

motors, therefore, the SMEV motion control is simplified to a

DC motor motion control. Controlling the performance of EV, in

particular, smooth driving for comfortable riding, is not a

simple task, where the design and operation parameters of EV,

Mechatronics Design of Small Electric Vehicles;

Research and Education

Farhan A. Salem1,2

1 Alpha Center for Engineering Studies and Technology Researches, Amman, Jordan .

2Mechatronics program,.

Dept. of Mechanical Engineering, Faculty of Engineering, Taif University, 888, Taif, Saudi Arabia.

Email: [email protected]



as well as the road condition are always varying, therefore, the

controller should be designed to make the system robust,

adaptive and improving the system on both dynamic and

steady state performances (fast responsive and low-ripple).

With reference to testing a maximum speed of 23 m/s, (that is

82.8 km/h) in maximum of 8 seconds, if an electric vehicle

with total mass m= 900 kg , friction coefficient of 0.19, air

density of 1.25 kg/m3 and aerodynamic factors of 0.75, the

surface area of vehicles 1.5 m2, width of 1 m , height of 0.5,

the gear ratio G, n at 2, wheel radius of 0.3 m, and maximum

power efficiency of 0.77

Battery Battery charger

Mechanic

al

transm

issi

on

Electric motorM

echanic

al

coup

ling

Power

converterDriversController

Tacho

Fig. 1. (a) Architecture of electric vehicle


Mech

an

ical

tran

sm

issio

n

Electric motor

Mech

an

ical

co

up

lin

gPower

converterDriversController

Tacho

Fig. 1. (b)Architecture of electric vehicle


Mech

an

ical

tran

smis

sio

n

Electric motor

Mech

an

ical

co

up

lin

g

Gasoline en.

Power converterDrivers

Controller

Fuel tank

Fig. 1. (c) Architecture of hybrid electric vehicle; Hybrid vehicle

combines an internal combustion engine and an electric motor.

II. SMEV SYSTEM MODELING

The SMEV system consists of two subsystems, the electric

motor and the vehicle systems; both will be modeled,

considering all acting forces and parameters, we will couple the

SMEV platform with the wheel rotational velocity via

characteristics of the electric motor and surface as well as to

derive the expressions for the acting forces, to calculate

required torque and power expressions, that can be used to

build the simulink model, finally, suggest, design and couple

control systems.

II. I ELECTRIC MOTOR MODELING

The electric vehicle is driven by an electric motor, the SMEV

motion control is simplified to an electric motor motion control

that may or not include gear system. In the proposed model,

for design and control of SMEV motion control, only the motor

and its associated driving power circuit can be replaced with

different types of electric motors used, also with different

electric motors, it is necessary to use different control

strategies. EV requires that the driving electric machine has a

wide range of speed regulation. In order to guarantee the

speed-up time, the electric machine is required to have large

torque output under low speed and high over-load capability,

and in order to operate at high speed, the driving motor is

required to have certain power output at high-speed

operation[6]. Presently, brushed DC motor, brushless DC

motor, AC induction motor, permanent magnet synchronous

motor (PMSM) and switched reluctance motor (SRM) are the

main types of motors used for electric vehicle driving [11].

DC machines are characterized by their versatility. By means of

various combinations of shunt-, series-, and separately-excited

field windings, they can be designed to display a wide variety

of volt-ampere or speed-torque characteristics for both

dynamic and steady-state operation. Because of the ease with

which they can be controlled, systems of DC machines have

been frequently used in many applications requiring a wide

range of motor speeds and a precise output motor control [13,

14]. The selection of motor for a specific electric vehicle is

dependent on many factors, such as the intention of the EV,

correspondingly allowable variation in speed and torque and

ease of control, etc. The dynamic equations of these motors

can be derived, mainly based on the Newton’s law combined

with the Kirchoff’s law. The fundamental system of

electromagnetic equations for any electric motor is given by

[16,17]

( ) (1)

ks

s s s s

kR

s R R b m R

s s s R

R R R S

du R i j

dt

du R i j P

dt

L i L i

L i L i

Where :k the angular speed of rotating coordinate system

(reference frame), Depending on motor construction (AC or

DC), the method of the supply and the coordinate system

(stationary or rotating with the rotor or stator flux) the above

mentioned model becomes transformed to the desirable

form[18], and the complement Eqs. (1) is equations describing

mechanical part of eclectic motor.

A series wound DC motor has the armature and field coils

connected in a series across the power source as shown in Fig.

2(b) A series wound DC motor is easy to use, will generate a

larger torque increase (startup torque) compared with a shunt



wound DC motor for given increase in current. Series motors

cannot be used where a relatively constant speed is required

under conditions of varying load." this means series wound

DC might not climb hills with varying slope briskly and

smoothly. The voltage supply is divided between stator and

rotor circuits and a common current flow through the field and

armature coils current ia, this all can be expressed as:

in a fV V V , ,m f ai i i

Applying Kirchoff’s law around the electrical loop,

( ) ( )a f

in a f a f a a

di diV s L L I R I R EMF

dt dt

( ) ( ) * *a f

in a f a f a mutual n

di diV s L L I R R L i

dt dt

Where :Lmutual :is the mutual inductance between the armature

winding and the field winding . Under steady state condition,

induction (L=0), gives:

( )in f a a aV s R I R I EMF

( )in a f aV s I R R EMF

The torque developed in the rotor is:

* * *m f fT K i K i

2 *m tT K i

The back EMF, also, can be expressed as:

* * ( * )b n b f a nEMF K I K K

Substituting, we have the armature current given by:

( )in

a

a f b m

V sI

R R K

And the developed torque given by:

2

2

*in t

a f t m

V KT

R R K

From this equation, if the input voltage Vin is kept constant, the

output angular speed is almost inversely proportional to the

square root of the torque, therefore a high torque is obtained at

low speed and a low torque is obtained at high speed. The sum

of the torques must equal zero, we have:

Te – Tα – Tω - TEMF = 0

Substituting the following values, gives : 2

2

2* 0mutual Load m m

d dL i T J b

dtdt

A shunt wound DC motor has the armature and field (stator)

coils connected in parallel (or shunt) across the power source,

in result the same voltage is applied to both coils this is shown

in Fig. 2(a). Shunt wound DC motor is designed for

applications where constant speed characteristics under

varying load conditions are important such as pumping fluids

and fans, shunt motor speed varies only slightly with changes

in load. A shunt wound DC difficult to control, as reducing the

supply voltage also results in a weakened magnetic field, thus

reducing the back EMF, and tending to increase the speed.

The stator and rotor circuits have the same voltage supply and

therefore the same voltage drop, and the current drawn by the

motor, im is the sum of the field current, if and armature current

ia, this all can be expressed as:

in a fV V V , m f ai i i

The DC shunt motor has the same equations for torque as for

the separately excited motor,

A compound wound DC motor is a combination of shunt wound

and series wound configurations as shown in Fig.2(c). This

allows the compound motor to be used in applications where

high starting torque and controlled operating speed are both

required.

The separately excited DC motor (Fig.2(d)) The voltage is

applied to both to field and armature terminals, as shown, there

are two currents, filed current, if and armature current, ia in

order to have linear system, one of these two currents most

held constant, this motor allows having independent control of

both the magnetic flux and the supply voltage, which allows

the required torque at any required angular speed to be set

with great flexibility. The biggest drawback is they are noisy. In

[12] the mathematical model, transfer function and simulink

model of separately excited DC motor were derived and built,

where from Eqs. (1);

The air-gap flux, Φ is proportional to the field current and

given by:

*f fK i 2

The back EMF voltage is given by:

3 EMF K* * - Im in a aV R

The torque developed by the motor is related linearly to air-gap

flux, Φ and the armature current ia(t), and given by:

1 * * ( )m aMotor Torque T K i t

Substituting (2) in (3), and rearranging to separate current ,we

have:

1 * * ( )* ( )m f a fT K K i t i t

1

( ) * * ( ) *

m m

f

f a b

T Ti t

K K i t K

4

Substituting (4) in (3), gives:

- K* * m

in m a

b

TV R

K

The torque developed, is given by:

K*

m in b n

a

T V KR

The transfer function relating input filed voltage Vin_field(s), and

motor output speed ωm(s), with armature current ia(t) held

constant and ,given by:

_

( )( )

( )

m

angle

in filed f f

KsG s

V s L s R Js b

, the transfer function relating input armature voltage to output

motor angular speed, with varying both armature current ia(t)

and field current if(t ) , and given by:



2

2

( )

( )1

t f

a f

armature b fielda a

a a a f

K I

R R bs

V s K VL J L Js s

R b R b R R b

Brushless DC motor (BLDC): The main disadvantages of

brushed DC motor drawback is that they need a commutator

and brushes which are subject to wear and require

maintenance, therefore have low life-span. the rotor (armature)

is composed of one or more permanent magnets, see Fig.2(f),

and coils for the stator (field). The rotor, being a permanent

magnet, simply follows the stator magnetic field around. The

speed of the motor is controlled by adjusting the frequency of

the stator power. In the BLDC motor, the electromagnets do

not move; instead, the permanent magnets rotate and the

armature remains static. The BLDC motor is actually an AC

motor. The wires from the windings are electrically connected

to each other either in delta configuration or WYE ("Y" -

shaped) configuration (see Fig.2(f))

The kinetics of the motor can be described as:

Te – Tα – Tω - TEMF = 0 2

20e Load m m

d dT T J b

dtdt

The generated electromagnetic torque, Te is given by:

* * *P a a b b c ce

e

n m

EMF i EMF i EMF iT

Where : Pe electromagnetic power of the motor, ea, eb, ec : the

back EMF in each phase . ia, ib, ic stator phase currents. Under

normal operation, only two phases are in conduction, therefore

the voltage balance equation, cross the two windings under

conduction, is given by:

( )( ) w

w w w w w

di tV R i t L EMF

dt

Induction motor is a type of alternating current motor where

power is supplied to the rotor by means of electromagnetic

induction. Stator windings are arranged around the rotor so

that when energized with a poly-phase supply they create a

rotating magnetic field pattern which sweeps past the rotor.

This changing magnetic field pattern induces current in the

rotor conductors, which interact with the rotating magnetic

field created by the stator and in effect causes a rotational

motion on the rotor. It has the advantages such as low-cost,

high-efficiency, high reliability, maintenance-free, easy for

cooling and firm structure, etc. making it especially competitive

in EV driving. Physical Model of 3-phase AC induction Motor

is shown in Fig.2(h) [6].

Permanent Magnets DC Motor,( Fig.2(e))

DC Motor and its features can be tested and analyzed both by

control system design calculation and by MATLAB software.

The PMDC motor is an example of electromechanical systems

with electrical and mechanical components, a simplified

equivalent representation of PMDC motor's two components

are shown in Fig.2(g). DC motor is a closed loop system in

nature, the back EMF introduces a negative feedback signal

proportional to the motor speed, which enhances the damping

of the system. In [12] the detailed equations of deriving

mathematical model of PMDC are introduced, where can get

differential equation that describes the electrical characteristics

of PMDC motor, by applying Ohm's law, substituting and

rearranging, all that gives:

( ) ( )( ) a

in a a a b

di t d tV R i t L K

dt dt

(Las +Ra) I(s) = Vin(s) - Kb sθ(s) 5

And, we can get differential equation that describes the

mechanical characteristics of PMDC motor, by performing the

energy balance on the PMDC motor system; the sum of the

torques must equal zero, we have:

Te – Tα – Tω - TEMF = 0

Considering that system dynamics and disturbance torques

depends on platform shape and dimensions the mechanical DC

motor part, will have the form:

Kt *ia = Tα + Tω + Tload +Tf

The coulomb friction can be found at steady state, to be:

Kt *ia - b*ω = Tf

Simplifying and substituting, we have: 2

2* 0t Load m m

d dK i T J b

dt dt

KtI (s) = (Jm s + bm) s θ(s) 6

The PMDC motor open loop transfer function without any load

attached relating the input voltage, Vin(s), to the angular

velocity, ω(s), given by:

( )

( )( )

tspeed

in a a m m t b

KsG s

V s L s R J s b K K

2

( )( )

( ) ( ) ( ) ( )

tspeed

in a m a m m a a m t b

KsG s

V s L J s R J b L s R b K K

7

The geometry of the mechanical part determines the moment of

inertia, the mobile platform can be considered to be of the

cuboid or cubic shape, with the inertia calculated as shown

below, where the total equivalent inertia, Jequiv and total

equivalent damping, bequiv at the armature of the motor with

gears attaches, are given by: 2 2

1 1

2 2

3

12

equiv m Load equiv m Load

load

N Nb b b J J J

N N

bhJ

8

The equivalent mobile robot system transfer function will be

given by:



2

( ) /( )

( ) ( ) ( ) ( )

robot tspeed

in a equiv a equiv equiv a a equiv t b

s K nG s

V s L J s R J b L s R b K K

9

The next open loop transfer function, relating the armature

input terminal voltage, Vin(s) to the output terminal voltage of

the tachometer Vtach(s), with most corresponding load torques

applied are considered, is given by:

inV s *

( )( )

tach t

open

tach a a m m a a b t

K KG s

V s L s R J s b L s R T K K

Where :T the disturbance torque, is all torques including

coulomb friction, and given by:

T=Tload+Tf For high accuracy, the inertias of the gears and wheels have to

be included in the calculations, this value can be obtained from

literature or calculated using the equations for the inertia of a

cylinder since the gear has a form of cylinder, this can be

rewritten as follows: 2

2 1

2

( )equiv motor gear wheel

NJ J J J mr

N

Permanent magnet synchronous motor (PMSM)

A permanent magnet synchronous motor is a motor that uses

permanent magnets to produce the air gap magnetic field rather

than using electromagnets. Such motors have significant

advantages, such as high efficiency, small volume, light

weight, high reliability and maintenance-free, etc., attracting

the interest of EV industry. The PMSM has a sinusoidal back

EMF and requires sinusoidal stator currents to produce

constant torque[6].

The d-q model of PMSM is shown in Fig.2(i) Voltage equations

are given by:

* *d

d d d e q q

diV R i L L i

dt

* *d

q q q e d d b m

diV R i L L i K

dt

The equations giving the stator current can be written in the

following form:

1

*d d e q q

d

I V L iL s r

1

*q q e d d b m

q

I V L i KL s R

The electromagnetic torque developed by the motor is given

by:

30.5* ( )

2

b q

m d d q q d d

K IT P L I I L I I

The simulink model of series wound DC motor, shunt wound

DC motor, Permanent Magnets armature controlled DC Motors

are allmostly identical, the differences are in current filed or

armature applied to both torque and back EMF constants, this

can be seen by studying simulink models shown in Fig.3, the

simulink model of the filed current controlled DC motor is

shown in Fig.3(a), the simulink model of separately excited DC

motor is shown in Fig..3(b), Equivalent block diagram of

PMSM is shown in Fig. Fig.3(c) where Ts =Lq/Rs and ω=Pbωm,

and ea= ωψf = Pbωm ψf [18], the simulink model of PMDC motor

is shown in Fig. Fig.3 (d)

Fig. 2. (a) A shunt wound DC motor Fig. 2. (b) Series wound DC motor

Fig. 2. (c) Compound DC motor Fig. 2. (d) Separately excited DC

motor

Fig. 2. (e) PMDC motor Fig. 2. (f) BLDC motor equivalent

circuit [6]

mm

Electromechanical PMDC motor system

MECHANICAL component of PMDC motor systemELECTRIC component of PMDC motor system

Fig. 2. (g) Schematic of a simplified equivalent representation of the PMDC

motor's electromechanical components

Fig. 2. (h) Model of 3-phase AC

induction Motor[6]

Fig. 2. (i) The d-q model of PMSM



fi led

current

motor

torque

motor angular

speed

Motor linear

speed

1

Lf.s+Rf

filed

Transfer Fcn

1

J.s+B

Transfer FcnStep

12 V

Scope

1

s

Integrator

Km

Gain

Fig. 3. (a) Simulink model of the filed current controlled DC motor

fi led current motor torquemotor angular

speed

Motor l inear

speed

angular

speed

armature

Current,i Motor

Torque

Armature

Field

current

the armature current IS maintained constant ia(t) = ia= constant

SEPARETLY EXCITED DC MOTOR

Armature

inductance

mutual

inductance

Table: Parameters of the DC Motor.

Vf=240[V]

La=0.012[mH]

Va=240[V]

Lmutual=1.8[mH]

Rf=240[W]

J=1[Kg.m2]

Ra=0.6[W]

Cr=29.2[N.m]

Lf=120[mH]

Fc=0.0005[N.m.Sec/Rad]

-K-

rad2mps

V=W*r1

Km

motor

constant

linear speed

1/n

gear ratio

n=3.1

fc

friction

coefficient

1

Lf.s+Rf

filed

Transfer Fcn

1

Lf.s+Rf

field

angular

speed

Vin.

fi led

Vin

armature

V armature

V Field

1

J.s+B

Transfer Fcn

motor.mat

To File..

Step

12 V

Kb

Scope

Product1

Product

TloadLoad

torque

1

s

Integrator.,

1

s

Integrator.

1

s

Integrator,

1

s

Integrator

1/J

Inertia

Km

Gain

1/Lf

Field

inductance.

Cr

Couple

resisting

-K-

.1

.,

1

La.s+Ra

,.

1

Jequiv.s+bequiv

,

-K-

mutual

Inductance

La

armature

inductance1/Lf

Field

inductance

Rf

Field

resistance

Ra

Armature

resistance

1/La

Fig. 3. (b) Simulink model of separately excited DC motor

Fig. 3. (c) Equivalent block diagram (simulink model) of PMSM

angular

speed

Current,iTorque

EMF constant

Kt

torque

constant

-K-

rad2mps

V=W*r1linear

speed

1/n

gear ratio

n=3.1

Vin

1

La.s+Ra

Transfer function

1/(Ls+R)1

1

Jequiv.s+bequiv

Transfer function

1/(Js+b)1

Motor.mat

To File..Kb

TloadLoad

torque

Fig. 3. (d) Simulink model of PMDC motor.

II.II MODELING ELECTRIC VEHICLE, SMEV, DYNAMICS

When deriving an accurate mathematical model for SMEV, it is

important to study and analyze dynamics between the road,

wheel and SMEV considering all the forces applied upon the

EV system. The modeling of a SMEV system dynamics

involves the balance among the several acting on a running

SMEV forces, these acting forces are categorized into road-

load and tractive force. The road-load force consists of the

gravitational force, hill-climbing force, rolling resistance of the

tires and the aerodynamic drag force and the aerodynamics lift

force, where aerodynamic drag force and rolling resistance is

pure losses, meanwhile the forces due to climbing resistance

and acceleration are conservative forces with possibility to,

partly, recover. This resultant force is the sum of all these

acting forces, will produce a counteractive torque to the

driving motor, i.e., the tractive force.

The disturbance introduced to the EV system is changes in the

road surface inclination angle, α, it is required to design

controller to be robust and should have a disturbance

rejection. The disturbance torque to SMEV is the total

resultant torque generated by the acting forces, and given by:

aerod rolling climb Linear_acc angular_accF F F FTotalF F 10

To determine the electric battery capacity, we need to

estimated energy required of SMEV platform, the requested

power in kW that SMEV platform must develop at stabilized

speed can be determined by multiplying the total force with the

velocity of the SMEV, and given by:

( )* *Total TotalP F F 11

Electrical power (in watts) in a DC circuit can be calculated by:

P= I x V

Where: I is current in Amps and V is voltage. Based on

fundamental principle of dynamics the acceleration of the

vehicle is given: by

*

m totalP P

M

Where: Pm :The power available in the wheels of the vehicle.

M,ν: vehicle mass and speed

The total resistive torque, TotalT is the torque of all acting

forces. The driving force comes from the powertrain shaft

torque, which can be written as the wheel torque, given by:

* *wheel shaftT G T 12

This wheel torque provides the resultant driving, tractive force,

FTotal to the vehicle:

* *wheel shaft

Total

T G TF

r r

13

Referring to Fig.4, the relationship between the resultant

tractive force and the torque produced by the motor Tshaft ,can

be obtained as:

**

shaft Total

rT F

G 14

The vehicle inertia torque can, also, be defined by the

following relationship:

vehicl

Vehicl

dT J

dt

The relationship between the linear velocity of SMEV platform,

v, and the angular velocity of the electric motor is given by:

* /r G

Where: r: The tire radius of the mobile platform. G,n: The

transmission gearing ratio. TL: Tshaft is the torque produced by

the driving motor. η : The transmission efficiency. v: the

velocity of the vehicle. ω: the angular velocity of the motor. It

is required to couple the SMEV platform with the wheel

rotational velocity via characteristics of the electric motor and

surface such as the traction force, the torque, etc. as well as to

derive the expressions for the acting forces, to calculate

required torque and power expressions that can be used to

build the simulink models.

α

Traction force

F,νwind

Fgrafitation

Faerod

M*g

Ftractive

Fwheel_powertrain

ν = r ω

FLift

Fig. 4. (a)



αM*g

Road incl.

α

Fig. 4. (b)

Fig. 4. (a)(b) Forces acting on moving vehicle.

II.II.I Rolling resistance force, Frolling: is produced by

flattening of the tire at the contact surface of the roadway and

depending on the vehicle speed and it is proportional to the

vehicle weight, and is given by:

rolling _ r rF *C * *C *cos( )normal forceF M g 15

For motion on a level surface, α=0, cos(α)=1 , and Eq.(15)

becomes:

rolling _ r rF *C * *Cnormal forceF M g

In terms of the vehicle linear speed Eq.(15) becomes:

rolling r0 r1F M *g * C -C * * ( )sign

Where : M : The mass of the SMEV and cargo (Kg). g .Cr The

rolling resistance coefficients is calculated by the following

expression:

r

3.6C 0.01 1

100robot

The rolling resistance torque is given by:

rolling rT * *C *cos( ) * rM g r

II.II.II Aerodynamic Drag force , Faerod: is the force opposing

the motion of the SMEV due to air drag, the aerodynamic drag

force is function of mobile platform linear velocity, ν and given

by: 2

aerod dF 0.5* *A*C * vehicl 16

Considering car and wind speed Eq.(16) become:

2

aerod dF 0.5* *A*C * * ( )vehicle wind vehiclesign

2

aerod dF 0.5* *A*C * *vehicl wind vehicl windsign

The aerodynamics torque is given by:

2

aerod d

1T * *A*C * *

2vehicle rr

17

Where: Cd : Aerodynamic drag coefficient characterizing the

shape of the SMEV and can be calculated using the following

expression:

aerod

2

F

0.5DC

S

S: frontal area of SMEV, assuming shape of the SMEV is long

cylinder , Cd =0.80, for sphere Cd =0.47, and for

streamlined body Cd =0.04 . A: Cross-sectional area of

the SMEV where it is the widest, (m2) ν: The linear speed of the

SMEV (m/s), νo : The speed of the wind (m/s), against the

direction of the SMEV's motion, rr: Rotor winding resistance

(per phase), rr =0.0503 Ohm. ρ: The air density (kg/m3) at STP,

ρ =1.25, At 20°C and 101 kPa, ρ =1.2041, The air density is

calculated by Eq. (18) expression, where: ρo = 101325 Pa, sea

level standard atmospheric pressure, T0 = 288.15 K sea level

standard temperature. g = 9.81 m/s2.Earth-surface gravitational

acceleration. L = 0.0065 K/m temperature lapse rate. R =

8.31447 J/(mol*K) universal gas constant. M = 0.0289644

kg/mol molar mass of dry air: *

*

0

** 1

*

g m

R L

O

L hM

T

R T

18

II.II.III The aerodynamics lift force, Flift; is caused by

pressure difference between the SMEV's roof and underside,

and is given by:

19 20.5* * * *lift L vehicleF C B

Where: B : SMEV's reference area. CL: The coefficient of lift, (

CL to be 0.10 or 0.16), and can be calculated using the

following expression:

20.5L

LC

A

Where: L: lift, the air density (kg/m3) at STP, ρ =1.25, V:

velocity of SMEV, A: frontal area.

II.II.IV The force of wind , Fwind ; can be calculated by:

2

wind dF 0.5* *A*C * vehicle wind 20

II.II.V The hill-climbing resistance force Fclimb; while the

SMEV is moving up or down a hill, the weight of the SMEV will

create a hill-climbing resistance force directed downward, this

force will oppose or contribute to the motion, it is a

conservative force with possibility to, partly, recover. Two

components of gravity, the component of gravity in the

dimension of travel is the hill-climbing resistance force and is

given by:

climbF * *sin( )M g 21

Where: M : The mass of the SMEV and cargo (Kg). g: The

gravity acceleration (m/s2). α :Road or the hill climbing angle,

road slope (Rad.). If we assume the SMEV is on a level surface,

this force is zero, 0 = α ,sin(0)=0. The hill-climbing resistance,

slope, torque, is given by:

22 climb slopeF F = * *sin( ) * wheelM g r

II.VI The normal force Fnorm: is the force exerted by the road

on the mobile SMEV's tires, the magnitude of Fnorm equals the

magnitude of the Facc in the direction normal to the road, The

normal force Fnorm can be found as by:

2

norm climbF * *sin( ) 0.5* * * *lift LF F M g C B

23



II.VII The linear acceleration force Facc : is the force required

to increase the speed of the SMEV, The acceleration force is

the total tractive effort of the SMEV minus the summation of

forces opposing the motion of the SMEV and can be described

as a linear motion given by:

acc 2F * wheelJd d

M a M Mdt dtr

24

accF *

TdM a M M

dt J

Where: M : the mass of the SMEV and cargo, a : acceleration

experienced as a result of the force exerted by the motors or as

a rotational movement, ∑ T: the resultant torque acting on the

wheels (Nm), J: the total inertia of the SMEV (kgM2), Jwheel : the

inertia of the wheel (kgM2)

II.VIII The angular acceleration force Facc_angle , is the force

required by the wheels to make angular acceleration and is

given by: 2

acc_ angle 2F

wheel

GJ a

r 25

The angular acceleration torque is given by:

26

2 2

acc_ angle 2*wheel

wheel wheel

G GT r J a J a

r r

Substituting derived equations in total force equation, we have

r0 r1

2

d

Linear_acc 2

* *sin( ) M *g * C -C * * ( )

0.5* * A*C * *

F

Total

vehicl wind vehicl wind

wheel

F M g sign

sign

J dM

r

dt

Based on derived equations, a suggest simulink function block

model (shown in Fig. 11 that represents SMEV the dynamics,

and couple the SMEV with the wheel rotational velocity via

characteristics of the electric motor and surface.

III. CONTROL SYSTEM SELECTION AND DESIGN

Electric vehicle speed controller takes the nominally fixed

voltage from the power source (battery) and outputs a variable

voltage supply needed to control the motor speed. Its voltage

output to the drive motors changes in response to control

signals supplied by the user from foot pedal, [8] When the

pedal is pushed, the controller delivers electrical currents from

the battery to the motor; this gives the car acceleration to

accelerate to the desired output speed, the sensors sense the

actual output speed and fed it back to controller. the main

voltage conversion is done very efficiently using PWM

technique, where controller sends pulses of power to the motor

thousands of times per second, where very short pulses cause

the motor to go slowly and long pulses cause the motor to go

fast. There are many motor control system strategies that may

be more or less appropriate to a specific type of application

each has its advantages and disadvantages; the designer must

select the best one for specific application. In [9], [10]

The proposed control system composed of two loops, inner

and outer; The first loop is inner current regulation loop that

accomplishes current regulation control to meet the current

needs in accordance with the needs of electric vehicle, and the

second loop is outer speed regulation loop that adjusts the

speed of the motor (see Fig. 6).

PID controllers are ones of most used to achieve the desired

time-domain behavior of many different types of dynamic

plants. The sign of the controller’s output, will determine the

direction in which the motor will turn. The PID gains (KP, KI,

KD) are to be calculated and tuned experimentally to obtain the

desired overall desired response. The PID controller transfer

function is given by:

2

2

P ID

D DI D P IPID P D

K KK s s

K KK K s K s KG K K

s s s

The transfer function of PID control can be rewritten in terms

of derivative time and integral time to have the form:

2 11

1 I D IPID P D P

I I

T T s T sG K T s K

T s T s

Where: IT is the integral time P

I

K

K

and is the derivative time D

D

P

KT

K

PI controller: because of its simplicity and ease of design, PI

controller is widely used in variable speed applications and

current regulation of electric motors. The output of the PI

controller in time domain is defined by the following equation

(27)

0( ) ( ) ( )

t

C P IV t K e t K e t dt 27

Integrator is added to eliminate the steady state error in the

control variable. Taking Laplace transforms and manipulating

Eq. (27) will result in the following transfer function:

( ) ( )

I

P

P I P oPI

current PI P

KK s

K s K K s ZKKG s G s K

s s s s

( 1) 1( ) * * 1I

PI PI PI

I I

T sG s K K

T s T s

Where, Vc(t) is the output of the PI controller, KP is the

proportional gain, KI is the integral gain, and e(t) is the

instantaneous error signal Zo: zero of the PI-controller KP: the

proportional gain, KPI: the proportional coefficient; TI: time

constant. This transfer function, shows that, PI controller

represents a pole located at the origin and a stable zero placed

near the pole, at Zo=- KI/ KP, resulting in drastically eliminating

steady state error due to the fact that the feedback control

system type is increased by one. The PI pole and zero will

affect the response, mainly the PI zero, Zo=- KI/ KP, will

inversely affect the response and should be cancelled by

prefilter.



Systems design with prefilter; Prefilter is defined as a transfer

function Gp(s) that filters the input signal R(s) prior to

calculating the error signal. Adding a control system to plant,

will result in the addition of poles and/or zeros, that will effect

the response, mainly the added zero, will significantly inversely

effect the response and should be cancelled by prefilter,

therefore the required prefilter transfer function to cancel the

zero is given by (28). In general. The prefilter is added for

systems with lead networks or PI compensators. A prefilter for

a system with a lag network, mainly, is not , since we expect the

effect of the zero to be insignificant.

Pr ( ) O

efilter

O

ZG s

s Z

28

Controller with deadbeat response design: Deadbeat response

means the response that proceeds rapidly to the desired level

and holds at that level with minimal overshoot, The

characteristics of deadbeat response include; Zero steady

state error, Fast response, (short rise time and settling time)

and minimal undershoot, ±2% error band[19].

PI-controller with deadbeat response design: With PI

controller with deadbeat response design, the overall closed-

loop transfer function, T(s), will be of third order will and

contain a zero of the PI-controller, Zo, This zero will

significantly affect the response of the closed-loop system,

T(s), and should be eliminated while maintaining the

proportional gain (KP) of the closed-loop system that can be

achieved by a prefilter. Thus, the requiring pre-filter transfer

function [3]:

Pr ( ) PI

efilter

PI

ZG s

s Z

29

Referring to [19], The controller gains KP and K

I depend on the

physical parameters of the system, to determine gains that

yield optimal deadbeat response, the overall closed loop third

order transfer function T(s) in terms of Zo and/or KP and K

I, is

compared with standard third order transfer function given by

Eq. (24), and knowing that parameters α , and β are known

coefficients of system with deadbeat response given by

[19],also we choose ωn based on the desired settling time or

rise time , this way we obtain the optimal values of Zo and/or

KP and K

I , that yield optimal deadbeat response,(for third

order system α =1.9 and β=2.2) 3

tan 3 2 2 3( ) n

s dard

n n n

G ss s s

30

Current controller: The current control loop guarantees

limited variations of the current trough the inductor during

important load variations. The current regulation loop is the

inner loop connected to the stator circuit; this is shown in

Fig.5. In this paper we are to suggest to design current

regulator as PID or PI controller, in order to have small

overshoot and good tracking performance current regulation

can be designed as type-I system. In case current controller is

designed as PI regulator, the parameters of PI current controller

can be designed as the follows: The motor voltage can be

written as

(Las +Ra) I(s) = Vin(s) - Kb sθ(s) 31

The Laplace transformed equation of motor stator circuit, in

terms of input voltage Vin(s) and output current, I(s) is given

by

1

( ) in b a a

I s

V s K s s L s R

32

In practical systems, due to the fact that the electromagnetic

time constant is smaller than electromechanical time constant,

current regulation is faster than speed regulation. Hence,

speed regulation is faster than the variation of back EMF,

therefore, the effect of back EMF on current regulation loop

can be neglected, therefore (32), can be rewritten as

1

in a a

I s

V s L s R

In terms of time constant, motor stator circuit will have the

form:

1/

T s 1

a

in electric

I s R

V s

Where : Telectric electrical motor (stator circuit) time constant.

Depending on [15],[16] , the open loop transfer function of

current loop is given by:

_

1( )

( ) (2 1)

P

current loop

a electric s

KG s

R T s T s

The parameters of PI current controller can be deduced

depending upon generic open loop transfer function with

damping factor ζ=0.707and given by:

1( )

2 ( 1)genericG s

s s

4

a electric P

P I

s electric

R T KK K

T T

Therefore, the current regulator transfer function, PI controller,

is given by:

_

_ _

_

_ _ _

( )

( 1) 1( ) * * 1

I current

P

P current I P current

PI current

I

PI current P current P current

I I

KK s

K s K KG s

s s

T sG s K K

T s T s

Where: KP_current: the proportional gain; KI_current: integral gain;

TI: time constant of current regulator. mainly the PI zero, Zo=-

KI/ KP, will inversely affect the response and it could be

cancelled by prefilter, the required prefilter transfer function to

cancel the zero is given by:

Pr

1/( )

1 /

o I

efilter

o I

Z TG s

s Z s T

33

Speed regulator controller: The Speed regulation loop is the

outer loop, this is shown in Fig. 5. In this paper, in order to

have smooth driving for comfortable riding, no steady state



error and acceptable anti-disturbance capability at transient

state, we are to suggest designing speed controller as PID or

PI controller. In case speed controller is designed as PI

regulator, a PI transfer function given by:

_

_

_ _

_

_ _ _

( )

( 1) 1( ) * * 1

I

P

P I P

PI speed

PI speed P P

KK s

K s K KG s

s s

T sG s K K

T s T s

Where, KP_ω: the proportional coefficient of speed regulator;

KI_ω: the integral coefficient of speed regulator; Tω: time

constant of motor speed. Depending upon generic open loop

transfer function, the parameters of speed controller loop can

be found to be:

_ _2 4

P

P I

c c

KJK K

T T

Where: Tc is the sum time delay due to speed loop, The same

approach, with PI prefilter to cancel the zero, can be applied to

speed loop PI controller.

The inverter: The input voltage Vin to inverter is considered as

constant (36V), the main voltage conversion is done very

efficiently using PWM techniques, the output voltage is

adjustable via the duty cycle α ,of the PWM signal. The

transfer function of the inverter can be given as in [6] The PI

current controller is affecting the inverter switching frequency

to reduce the ripples in the torque and current

( )1

PWM

converter

s

KG s

T s

Where: Kpwm: gain of inverter; Ts: time constant of PWM

controller, (to be 0.25 ms)

IV. SIMULATION AND RESULTS

The SMEV subsystems; including the electric motor, the

vehicle systems and dynamics considering all acting forces

and control system; all was modeled and coupled, were SMEV

is coupled with the wheel rotational velocity via characteristics

of the electric motor and surface and both coupled with control

systems. The simulink model is shown in Fig. 6. Three control

strategies are introduced; first strategy controlling both loops;

current and speed loops with two separate PID controllers for

each, second strategy, controlling the whole system with one

PID controller and third strategy controlling both loops;

current and speed loops with two separate PI controllers for

each current and speed loop. The simulation of these

strategies are shown in Fig.7(a)(b)(c), For our design and

simulation, the desired output max linear speed is to be 23 m/s,

(that is 82.8 km/h)

Running simulink model applying two separate PI controllers,

one for inner current regulation and other for outer speed

regulation will result in linear speed/time curve shown in Fig. 8

, adding PI controllers prefilter to simulink block, will eliminate

the affect of PI zeros on the response, resulting in more

improved response in the form of smooth driving for

comfortable riding. Replacing, in Fig Fig.6, both PI controllers,

for current and speed regulation, with the derived PID

controllers, defining parameters, running simulink model will

result in speed curve shown in Fig. Fig. 9,

Now, Removing PID controller for the current loop, and

running simulink model with one general PID controller for the

whole SMEV, and tuning PID gains values, will result in speed

curve shown in Fig. 10. The obtained response curves show

that, applying two separate PI controllers , for both inner

current loop and outer speed loop, will result in more improved

response in the form of smooth driving for comfortable riding,

minimum settling time and less power consumption.

Fig. 6. General Simulink model of SMEV using PI-controller for both,

inner current and outer speed regulation loops.

Volt(0:36)

-K-

vehicle anglular feedbacK.

s

Tw.s+1

Tw.s

Speed regulator

PI Controller

1/Tw

s+1/Tw

Speed loop

prefilter

Kb

S1S

Manual Switch

s+1/Ti

1/Ti

Current loop

Prefilter

1

Constant11

Constant

Add.1Add,

Kpw

,.

Fig. 7. (a)

Fig. 7. (b) Two PID controllers for both inner current and outer speed

regulations loops.

speed regulator

PI Controller

EMF constant Kb

Speed regulator

PI controller

-K-

vehicle anglular

feedbacK

Kpwm

Ts.s+1

inverter TF .2

Kpi*Ti.s+Kpi

Ti.s

current regulator

PI Controller.1

Kb

Add.3Add

Kpw

.,1

Kpw

.

Tw.s+1

Tw.s

-1

(speed)

Tw.s+1

Tw.s

Fig. 7. (c) PI controllers for both; inner current and outer speed

regulation loops.

0 2 4 6 8-10

0

10

20

30

sec

Rad/

sec

Angular speed/time

0 2 4 6 8-10

0

10

20

30

sec

m2

Acceleration/time

0 2 4 6 8-10

0

10

20

30

sec

m2

Acceleration/time

0 2 4 6 8-10

0

10

20

30

sec

Rad/

sec

Angular speed/time

0 2 4 6 8-10

0

10

20

30

sec

m2

Acceleration/time

0 2 4 6 8-10

0

10

20

30

sec

m2

Acceleration/time

Fig. 8. (a) Fig. 8. (b)

Fig. 8. (a) linear speed/time and (b) acceleration/time responses of SMEV

using two separate PI controllers for inner current and outer speed loops.



0 5 10-50

0

50

100

sec (s)

Rad

/sec

Angular speed/time

0 5 10-10

0

10

20

30

sec (s)

M/s

Linear speed/time

0 5 100

500

1000

sec (s)

Am

p

Current/time

0 5 10-100

0

100

200

300

sec (s)

Nm

Torque/time

Fig. 9(a) Fig. 9(b)

Fig. 9. (a)(b) Two linear speed/time of SMEV response curves using two

PID controllers for current and speed regulations loops, obtained for

different values of PID gains.

0 2 4 6-50

0

50

100

Time (seconds)

Rad/s

ec

Angular speed/time

0 2 4 6-10

0

10

20

30

Time (seconds)

M/s

Linear speed/time

0 2 4 60

500

1000

1500

Time (seconds)

Am

p

Current/time

0 2 4 6-200

0

200

400

600

Time (seconds)

Nm

Torque/time

Fig. 10. linear speed/time of SMEV using one PID controller for whole

SMEV system.

V. A SUGGESTED FUNCTION BLOCK WITH ITS FUNCTION

BLOCK WITH IT 'S PARAMETERS WINDOW FOR

MECHATRONICS SMEV DESIGN, TESTING AND VALIDATING.

To simplify and accelerate Mechatronics design process of

SMEV in terms of most mechanical components and control

system selection and integration, a function block with its

function block parameters window is proposed, shown in Fig.

11, , this function block can be used as follows: using

supporting m.file , designer is to define form, dimensions and

weight of required SMEV, define required variables and

coefficients for calculating acting forces e.g. CD, CL A, also

selected controller and its corresponding gains and/or zeros,

use manual switch to switch between controller types, PI,PD,

PI with prefilter, PID for the whole system , one PID for current

loop and other PID for speed loop, one PI for inner current

loop and other PD for outer speed loop, finally run the

suggested model with defined parameters, analyze, evaluate

and decide.

VI. FUNCTION BLOCK TESTING AND RESULTS

Switching the proposed model, to PID control strategy for

both, inner and outer, loops, defining mechanical system

parameters, and defining variables and coefficients for

calculating acting forces, then running model for desired

output linear speed of 23m/s (82.8 km/h), will return response

curves shown in Fig. 12, curves show that using PID

controller for both loops, will result in system response with

overshoot and allmostly, but not smooth driving for

comfortable riding, as well as settling time is about 1.4

seconds.

Now, making use of simulink PID built-in block capabilities, to

switch it to PI for inner current loop, and PD for outer speed

loop , then running model for desired output linear speed of

23m/s (82.8 km/h), and tuning ,will return response curves

shown in Fig. 13(a). Now, keeping same arrangement (PI and

PD controller) but switching input signal to motion profile will

return response curves shown in Fig. 13(b). Response curves

show that using PI controller for inner current loop and PD for

outer speed loop, will result in system response without

overshoot and in smooth driving for comfortable riding, as well

as settling time is about 1.8 seconds

Switching the general model, to PI control with prefilter for

both , inner and outer, loops, considering that the time

constants (speed gain Kpw=3.3, speed time constant

Tw=0.009 , current regulator and current prefilter values Kpi =

1.51, time constant Ti=0.08, and inverter time constant

Ts=0.0025, Kpwm=5), Running model for desired output linear

speed of 23m/s ( 82.8 km/h), will return response curves shown

in Fig. 14 , settling time is about 5.3 seconds , the performance

of SMEV is controlled desired response that is with smooth

driving for comfortable riding,

The proposed model can be modified, where only the electric

motor can be replaced with different types of electric motors

most used for EV, also with different electric motors, it is

necessary to use different control strategies, model can be

modified to include PI with dead beat response and IMC

control.

0 1 2 3-10

0

10

20

30

Seconds (s)

lin

. speed M

Linear speed/time

0 1 2 3-50

0

50

100

Seconds (s)

ang.

speed R

ad/s

ec

Angular speed/time

0 1 2 3-50

0

50

100

150

Seconds (s)

Accele

r. m

/sec

2

linear acceleration m/sec2

0 1 2 3-500

0

500

1000

Seconds (s)

Torq

ue N

mTorque/time

Fig. 12. (a) Linear speed/time, angular speed/time, current/time,

torque/time, response of SMEV for desired output linear speed of 23

m/s (that is 82.8 km/h) applying PID control for both inner and outer

loops



0 2 4 6-10

0

10

20

30

Seconds (s)

lin

. speed M

Linear speed/time

0 2 4 6-50

0

50

100

Seconds (s)

R

ad

Angular speed/time

0 2 4 6-10

0

10

20

Seconds (s)

m


0 2 4 6-100

0

100

200

300

Seconds (s)

Torq

ue N

m

Torque/time

Fig. 12. (b) Linear speed/time, angular speed/time response,

current/time, torque/time, of SMEV for desired output linear speed of

23 m/s (that is 82.8 km/h), applying PID control for both inner and

outer loops and adding current limiting saturation block (±250)

0 2 4 6-10

0

10

20

Seconds (s)

lin

. speed M

Linear speed/time

0 2 4 6-20

0

20

40

60

Seconds (s)

R

ad

Angular speed/time

0 2 4 6-10

0

10

20

30

Seconds (s)

m


0 2 4 6-50

0

50

100

150

Seconds (s)

Torq

ue N

m

Torque/time

Fig. 13. (a) Linear speed/time, angular speed/time Linear

acceleration/time, current/time, torque/time, response curves of SMEV

for desired output linear speed of 23 m/s (that is 82.8 km/h), applying

PD control for outer speed loop and PI for inner current loop .

0 5 10 15-5

0

5

10

Seconds (s)

lin

. speed M

Linear speed/time

0 5 10 15-20

0

20

40

Seconds (s)

R

ad

Angular speed/time

0 5 10 15-5

0

5

10

15

Seconds (s)

m


0 5 10 15-50

0

50

100

Seconds (s)

Torq

ue N

m

Torque/time

Fig. 13. (b) Linear speed/time, angular speed/time Linear

acceleration/time, current/time, torque/time, response curves of SMEV

applying motion profile input and applying PD control for outer speed

loop and PI for inner current loop .

0 2 4 6 8-10

0

10

20

30

Seconds (s)

lin

. speed M

Linear speed/time

0 2 4 6 8-50

0

50

100

Seconds (s)

R

ad

Angular speed/time

0 2 4 6 8-10

0

10

20

Seconds (s)

m


0 2 4 6 8-100

0

100

200

300

Seconds (s)

Torq

ue N

m

Torque/time

Fig. 14. Linear speed/time, angular speed/time Linear

acceleration/time, torque/time, response curves of SMEV for desired

output linear speed of 23 m/s (that is 82.8 km/h), applying PI

controller with prefilter for both , inner and outer, loop

speed regulator

PI Controller

angular

speed

Load

Dynamics

EMF constant Kb

input (0:36)

-K-

vehicle anglular feedbacK.

-K-

rad2mps

V=W*r1

linear speed.

Kpwm

Ts.s+1

inverter TF .

1/n

gear ratio

n=3.1

Kpi*Ti.s+Kpi

Ti.s

current regulator

PI Controller.2

1

den(s)

Transfer function

1/(Js+b).

Tw.s+1

Tw.s

Speed regulator

PI Controller

Kb

-K-

Kt.Add.1Add,

Kpw

.,1

-K-

.

Tw.s+1

Tw.s

-1

Kpw

,.

1

La.s+Ra

,,

Fig. 5. SMEV model inner current and outer speed loops.



r/2Rolling resistance force

M*g*Cr*cos()

aerodynamics lift force

r*m/2r*m/2

angular

speedTorquecurrent

Coloum friction

10

OUTER LOOP from

summing d1

9INNER LOOP from

summing d3

8

OUTER LOOP from summing d2

7

OUTER controller output

6INNER controller

output5

linear speed

in m/s

4 Current, I

3

output anguale speed, Omega

2T, Torque,

1Acceleration

in m/(s 2)

1

wheel radius,

V=W*r2

-K-

rads2mps=

R_wheel*(2*pi)/(2*pi).1

-K-

r^2m/2. correct2

0.5

r*m*g/2 , correct2

r^2*m*g/1

d2d1

Cd

aerodaynamic torque,

0.5*p*A*Cd*v^1

1

den(s)

Transfer function

1/(Js+b).

sin(u)

cos(u)

SinCos.1

Saturation

1

s

Integrator1

Divide50

Divide49Divide48

Divide47

Divide46Divide45

Divide43

Divide42

Divide41

Divide40

Divide39

Divide37Divide36

Divide35Divide34

Divide33Divide32

Divide31

Divide25

Divide24Divide23

Divide20Divide19

Divide1

Divide,2 du/dt

Derivative1

du/dt

Derivative,1

Cd

Cd=0.1

87

610

CL

.1

0.5.

.1

1,1

1

3

1

2

1

11

24Inclination angle (0:75)1

23

Cr: The roll ing resistance coefficients1

22P: The invironment ( air) density (kg/m3) 2

21A:Cross-sectional area of SMEV, where it is the widest, (m2)1

20Cd : Aerodynamic drag coefficient1

19

Kb, EMF constant

18Current PI Prefilter17Speed PI Prefilter

16 Inverter

15B : SMEV underside area1

14CL: The coefficient of l ift, ( CL to be 0.10 or 0.16)1

13

g: The gravity acceleration (m/s2).1

12

M : The mass of the mobilr robot 1

11

r, wheel radius10Kt, Torque

constant

9

R, Armature Resistance

8L, Armature

Inductance

7 All viscous damping

6

Ktac, Tachometer constant , 5

n, Gear ratio

4 Inertia motor+ load

3PI or PID (Inner current)

2PI or PID (outer speed)

1

Vin, Input Volt,(0 :30)

Fig. 11. (a) SMEV actuator subsystem

Speed regulator

PI Controller

r

r

n

n

Kpwm

Ts.s+1

inverter TF .

9.8

g

Kpi*Ti.s+Kpi

Ti.s

current regulator

PI Controller.

acceleration

Torque

Out1

Subsystem3

Out1

Subsystem1

Vin, Input Volt,(0 :30)

PI or PID (outer speed)

PI or PID (Inner current)

Inertia motor+ load

n, Gear ratio

Ktac, Tachometer constant ,

All v iscous damping

L, Armature Inductance

R, Armature Resistance

Kt, Torque constant

r, wheel radius

M : The mass of the mobilr robot 1

g: The grav ity acceleration (m/s2).1

CL: The coef f icient of lif t, ( CL to be 0.10 or 0.16)1

B : SMEV underside area1

Inv erter

Speed PI Pref ilter

Current PI Pref ilter

Kb, EMF constant

Cd : Aerody namic drag coef f icient1

A:Cross-sectional area of SMEV, where it is the widest, (m2)1

P: The inv ironment ( air) density (kg/m3) 2

Cr: The rolling resistance coef f icients1

Inclination angle (0:75)1

Acceleration in m/(s 2)

T, Torque,

output anguale speed, Omega

Current, I

linear speed in m/s

INNER controller output

OUTER controller output

OUTER LOOP f rom summing d2

INNER LOOP f rom summing d3

OUTER LOOP f rom summing d1

Subsystem

Step Input Volt(0:36)

1/Tw

s+1/Tw

Speed loop

prefilter

Signal 1

Signal Builder

P

Rou, air

0

Road slope

Ramp Input Volt(0:36)

Ra

RaPID(s)

PID current

PID(s)

PID speed

Manual

Switch

m

M

Linear speed

La

La

Ktach

Ktach

Kt

Kt

-C-

Kb, EMF

s+1/Ti

1/Ti

Current loop

Prefilter

Current

Cr

Cr

CL

Cl

Cd

Cd

-C-

B4

-C-

B3

B

B

Angular speed

A

A

Kpw

.,

Tw.s+1

Tw.s

-

electic_vehicl4.mat

,4

electic_vehicl3.mat

,3

electic_vehicl2.mat

,2

electic_vehicl1.mat

,1

electic_vehicl5.mat

,

6

4

3

2

1

Fig. 11. (b) Function block with its function block with it's parameters window for SMEV design, testing and validating



VI. CONCLUSION

Mechatronics design of small electric vehicles (SMEV),

including Mechatronics design of accurate general models

and control are proposes, the proposed model can be used

to select, integrate, analyze and validate, both mechanical

system with all acting forces and control system, resulting in

simplification, acceleration and increasing accuracy of

mechatronics design of SMEV. The proposed model

intended to be used for research purposes as well as, for the

application in educational process.

Testing the models and analysis of resulted response

curves show that, applying two separate PI controllers with

corresponding prefilter, for both inner current loop and

outer speed loop, will result in more improved response in

the form of smooth driving for comfortable riding of SMEV

and minimum settling time.

The proposed model can modified to include any control

strategy and/or any electric motor, where the motor and its

associated driving power circuit and /or controller can be

replaced with different motors and/or control strategy,

include PI with dead beat response and IMC control. to

overcome the drawbacks of PI and PID controllers, mainly

re-tuning process when the operating condition changes

and motor’s parameter variations, an m.file can be written to

calculated the desired values as well as PI-Fuzzy Controller

can be designed

REFERENCES

[1] Asif Faiz, Christopher S. Weaver, Michael P. Walsh, an air

pollution from motor vehicles, , standards and technologies for

controlling emissions, the world bank Washington, D.C. 1996.

[2] Bambang Sri Kaloko, Soebagio, Mauridhi Hery Purnomo,

Design and Development of Small Electric Vehicle using

MATLAB/Simulink, international Journal of Computer

Applications (0975 – 8887) Volume 24– No.6, June 2011

[3] Dhameja, S., 2002, Electric Vehicle Battery Systems, Newnes,

United Stated.

[4] Husain, I., 2003, Electric and Hybrid Vehicles Design

Fundamentals, Pertama, CRC Press, United Stated.

[5] Larminie, J., Lowry, J., 2003, Electric Vehicle Technology

Explained, John Wiley & Son

[6] Qi Huang, Jian Li and Yong Chen, Control of Electric Vehicle,

University of Electronic Science and Technology of China

P.R.China.

[7] A. Shekeena1, P. V. R. L. Narasimham, Hybrid control of

brushless DC motor for variable speed application, International

Journal of Computer Science and Management Research, Vol 1

Issue 3 October 2012

[8] http://buggies.builtforfun.co.uk/FactFiles/controller.html

[9] Farhan A. Salem, Ahmad A. Mahfouz, Modeling and controller

design for PMDC motor, using different control strategies and

verification using MATLAB/Simulink , Submitted and accepeted

but not puplished yet to I.J. Intelligent Systems and

Applications, Submission ID 124 , 2012

[10] Hedaya Alasooly, ''Control of DC motor using different control

strategies'' global journal of technology and optimization 2011

[11] Chan, C.C. (1999). The Past Present and Future of Electric

Vehicle Development. IEEE Power Electronics and Drive

Systems,1999, pp.11-13

[12] Ahmad A. Mahfouz, Mohammed M. K, Farhan A. Salem

Modeling, simulation and dynamics analysis issues of electric

motor, for mechatronics applications, using different

approaches and verification by MATLAB/Simulink (I).

Submitted and accepeted but not puplished yet to I.J. Intelligent

Systems and Applications, Submission ID 123 , 2012.

[13] Halila A., Étude des machines à courant continu, MS Thesis,

University of LAVAL, (Text in French), May 2001.

[14] Capolino G. A., Cirrincione G., Cirrincione M., Henao H., Grisel

R., Digital signal processing for electrical machines,

International Conference on Electrical Machines and Power

Electronics, Kusadasi (Turkey), pp.211-219, 2001.

[15] Hamdy Mohamed Soliman, S.M.EL. Hakim Improved Hysteresis

Current Controller to Drive Permanent Magnet Synchronous

Motors through the Field Oriented Control International Journal

of Soft Computing and Engineering (IJSCE) ISSN: 2231-2307,

Volume-2, Issue-4, September 2012.

[16] M.P.Kazmierkowski, H.Tunia "Automatic Control of

Converter-Fed Drives", Warszawa 1994

[17] R.D. Doncker, D.W.J. Pulle, and A. Veltman. Advanced Electri-

cal Drives: Analysis, Modeling, Control. Springer, 2011.

[18] Grzegorz SIEKLUCKI,Analysis of the Transfer-Function

Models of Electric Drives with Controlled Voltage Source

PRZEGL ˛ AD ELEKTROTECHNICZNY (Electrical Review),

ISSN 0033-2097, R.88NR7a/2012

[19] Richard C. Dorf and Robert H. Bishop. Modern Control

Systems. Ninth Edition, Prentice-Hall Inc., New Jersey, 2001.

Authors’ Profile:ta

Farhan Atallah Salem : B.Sc., M.Sc

and Ph.D., in Mechatronics of

production systems, Moscow state

Academy. He is author and co-author of

textbooks and scientific papers in

Refereed Journals. Now he is ass.

Professor in Taif University,

Mechatronics program, Dept. of

Mechanical Engineering and gen-

director of alpha center for engineering

studies and technology researches.

Research Interests; Design, modeling

and analysis of primary Mechatronics Machines, Control selection,

design and analysis for Mechatronics systems. Rotor Dynamics and

Design for Mechatronics applications

mechatronics design of small electric vehicles; research - ijens

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