Vehicle Technologies

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 1/16

MAK 4053E Vehicle Technology

1

 Vehicle TechnologyMAK 4053ELecture 1b – Introduction to VehicleTechnology Theory

Instructor: Dr. Özgen Akalın Associate Professor of Mechanical Engineering

Slides do not cover the complete course material and can not beused as a single resource.

Classroom use only!

Driver

Performance

Handling

Ride Vehicle

Ground conditions

 Aerodynamic inputs

 Visual and other inputs

 Accelerator, Brakes

Steering system

Surface irregularities

The driver-vehicle-ground system 

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 2/16

MAK 4053E Vehicle Technology

2

There are some things that you just don’t

want to try experimentally!

It is much safer to approach

stability thresholds in

simulation than in practice.

Fundamental approach to modeling

! 

Dynamic behavior of a vehicle is determined by theforces imposed on the vehicle from tires, gravity, andaerodynamics.

!

  The vehicle and its components are studied todetermine what forces will be produced by each ofthese sources at a particular maneuver and trimcondition, and how the vehicle will respond to theseforces.

! 

For that purpose it is essential to establish a rigorousapproach to modeling the systems and conversionsthat will be used to describe motions.

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 3/16

MAK 4053E Vehicle Technology

3

Problem Formulation

! 

Basically, the entire formulation of the problem is howto abstract from the physical world into some type ofanalytical description.

 physical

systemlevel of

abstraction

0)0t(

 );t,,()t(

xx

uxf x

==

=!

ODE

model

?

Single DOF ! Car Suspension

!  First approximation: as a 1st approx. to avehicle suspension system, let’s consider

the!

 car, single DOF system:

mCar body

(sprung mass)

independent

suspension

k  b

z 

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 4/16

MAK 4053E Vehicle Technology

4

! 

Now, if we include the unsprung mass dynamicswe have:

!  Here we treat the tire as a linear spring element withno damping

Two DOF! Car Suspension

ms

mu 

zs

k s  bs

k t

zu

zr road displacement

unsprung mass displacement

sprung mass displacement

Displacements measured

from equilibrium

" Car Model and Coupling Effect

ms, I ! 

 b a

z

k sr

k tr

 bsr k sf

k tf

 bsf

zur

zrr

zuf

zrf

mur muf

zsr zsf

forward

velocity

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 5/16

MAK 4053E Vehicle Technology

5

 r 

 b 

 a 

 - v 

 u 

 V 

$

  2 

$

  1 

 F  y 2  z 2 

 F  y 1 

 z 1 

 V e h i c l e 

 s l i p  a n g 

 l e 

 S t e e r i n g   a n g 

 l e 

Simplified steady-state handling model fora two axle vehicle. (Bicycle model)

Simplified steady-state handling model fora two axle vehicle. (Bicycle model)

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 6/16

MAK 4053E Vehicle Technology

6

Seven DOF ride model for passenger car

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 7/16

MAK 4053E Vehicle Technology

7

Interpretation of Results

! 

If you have the resources ($), you can get a nicepackage that has extensive GUI front ends andvisualization tools

GUI interface Parameter

adjustmentVisualization

tools

Interpretation of Results

!  ADAMS!

http://www.mscsoftware.com 

!  CARSIM!  http://www.carsim.com/  

!  CARMAKER!  http://www.ipg.de/CarMaker.609.0.html  

!  VAMPIRE (Rail)! 

http://www.vampire-dynamics.com/

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 8/16

MAK 4053E Vehicle Technology

8

 ADAMS

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 9/16

MAK 4053E Vehicle Technology

9

CARSIM

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 10/16

MAK 4053E Vehicle Technology

10

CARSIM

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 11/16

MAK 4053E Vehicle Technology

11

BIKESIM

Interpretation of Results

VR/w simulation

!   Actually, a lot of vehicle related video games run ondynamic simulations of vehicle models

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 12/16

MAK 4053E Vehicle Technology

12

Large motion simulator from Simtec GmbH at the DLR in Braunschweig, Germany.

University of Iowa, National Advanced Driving Simulator.

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 13/16

MAK 4053E Vehicle Technology

13

University of Iowa, National Advanced Driving Simulator.

 Vehicle Axis SystemsBody Fixed Coordinate system

SAE Definition

Ref. Milliken & Milliken, Race Car Vehicle Dynamics, SAE Press 1995, p. 116

CG

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 14/16

MAK 4053E Vehicle Technology

14

 Vehicle in Earth Fixed Coordinate System

Body Fixed and Earth Fixed Coordinates

! 

We will use these transformations between Body-fixed and Earth-fixed coordinates when discussingthe planar dynamics of the vehicle.

!  Bicycle model

! 

This will involve transforming vehicle coordinates totraffic lane coordinates.

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 15/16

MAK 4053E Vehicle Technology

15

Body Fixed and Earth Fixed Coordinates

!  The same approach must be used for other

maneuvers too. 

Lane change

yaw

rate

lateralvelocity

t

Wheelbase

Track width (rear)

7/23/2019 Vehicle Technologies

http://slidepdf.com/reader/full/vehicle-technologies 16/16

MAK 4053E Vehicle Technology

Direction

RWD FWD 4WD

Ff FfFf Ff

FrFr Fr Fr

F  F F 

Drive types

Dynamic axle loads

L 

l  1  

l  2  

W   

r  s t  

W   f   

W   r  

h  

L 

l  1  

l  2  

W   W  

f   

W  r  

h  

R a  

h a  

d  

R d z  

R d x  

h d  

R x f  

R x r  

F f  

F r  

Wsin! 

Wcos! ax

Wax /g

!