APOLLO Intelligent Tyre Systems – State of the Art and Potential

107 Pages·2003·3.33 MB·English

APOLLO

IST-2001-34372
Intelligent Tyre for Accident-free Traffic

Intelligent Tyre Systems – State of the Art and
Potential Technologies

Deliverable D7

Report Version: 1
Report Preparation Date: 22.05.2003
Classification: Public
Contract Start Date: 01.03.2002 Duration: 36 months

Project Co-ordinator: Technical Research Centre of Finland (VTT) FI
Partners: DaimlerChrysler AG (DC AG) D
Helsinki University of Technology (HUT) FI
Rheinisch Westfälische Technische
Hochschule Aachen (RWTH Aachen) D
IXFIN Magneti Marelli Sistemi
Elettronici S.p.A (MM) I
Nokian Tyres plc (NR) FI

Pirelli Pneumatici SPA (PIRELLI) I

Project funded by the European Community
under the “Information Society Technology”
Programme (1998-2002)
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

DELIVERABLES SUMMARY SHEET

Project Number: IST-2001-34372
Project Acronym: APOLLO
Title: Intelligent Tyre for Accident-free Traffic

Deliverable N°: D7
Due date: 31.12.2002
Delivery Date: 22.05.2003

Short Description: Intelligent Tyre Systems – State of the Art and Potential Technologies
This document provides an overview on the state of the art of intelligent tyre systems and
potential technologies that can be utilised for sensors, wireless data transmission, and
batteryless power supply. An accident analysis with an investigation of tyre-related risk
factors shows the great benefit of the envisaged system to improve traffic safety. This fits to
visions and strategies of vehicle manufacturers, automotive suppliers and tyre manufactures
in respect to intelligent tyre/wheel systems that are summarised. The first products that have
been introduced in the field of intelligent tyres are Tyre Pressure Monitoring Systems
(TPMS). Different system solutions for TPMS and activities of suppliers are described. More
sophisticated sensor systems, that are still in the process of research or pre-development,
show the high interest in this field. Basic sensor technologies which enhance the realisation
potential for innovative monitoring of tyre and tyre-road contact are presented. Radio
communication is a technology with a high potential for high performance wireless data
transmission. Applications for different systems, future trends, aspects of vehicle integration
and standards are discussed. First investigations on inductive transmission and power
generation prove the potential of these technologies for the development of a batteryless
power supply. Promising results of a pre-study, showing measurements of electromagnetic
properties of the tyre/wheel system, are presented. An overview is given on selected patent
applications for systems and key components of intelligent tyre/wheel systems.
Following the approach of the APOLLO project is a promising perspective to achieve a
successful product for an intelligent tyre/wheel system which allows to expect over 4 000
saved lives in all EU countries every year.

Partners owning: The APOLLO consortium
Partners contributed: VTT, DC AG, HUT, RWTH Aachen, MM, NR, PIRELLI
Made available to: European Commission, Information Society Directorate-General

IST-2001-34372 Page 2
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

Table of Contents

1. Introduction...................................................................................................................5
2. Accident Analysis..........................................................................................................8
2.1 Introduction...............................................................................................................8
2.2 Finland......................................................................................................................9
2.3 Germany.................................................................................................................11
2.4 Conclusion ..............................................................................................................13
3. Trends and Strategies ................................................................................................15
3.1 Vehicle manufacturers.............................................................................................15
3.2 Automotive electronics suppliers.............................................................................17
3.3 Tyre manufacturers and co-operations....................................................................19
4. Tyre Pressure Monitoring Systems (TPMS)................................................................21
4.1 Indirect measurement..............................................................................................21
4.2 Direct measurement - active sensors......................................................................22
4.2.1 Battery-operated sensor technology in general.................................................22
4.2.2 Clamp-on-rim sensors.......................................................................................23
4.2.3 Valve-attached sensors.....................................................................................25
4.2.4 Valve-cap-integrated sensors ...........................................................................31
4.3 Direct measurement - passive sensors...................................................................34
4.3.1 Introduction on batteryless sensor technology..................................................34
4.3.2 Batteryless TPMS at 2.4 GHz...........................................................................35
4.3.3 Other systems...................................................................................................36
4.4 Conclusion ..............................................................................................................38
5. Advanced Tyre Sensor Systems.................................................................................39
5.1 Side Wall Torsion sensor........................................................................................39
5.2 Darmstadt tyre sensor.............................................................................................41
5.3 Surface Acoustic Wave sensor ...............................................................................43
5.4 Conclusion ..............................................................................................................45
6. Basic Sensor Technologies........................................................................................46
6.1 Introduction.............................................................................................................46
6.2 Acoustic sensor.......................................................................................................46
6.3 Optical sensor.........................................................................................................46
6.4 Vibrating string sensor.............................................................................................49
6.5 Ultra Wide Band technology....................................................................................50
6.6 Capacitive sensor....................................................................................................52
6.6.1 Micromechanical sensor...................................................................................52
6.6.2 Capacitive displacement sensor .......................................................................53
6.6.3 Measurement of capacitance............................................................................55
6.7 Conclusion ..............................................................................................................56
7. Basic Technologies for Wireless Data Transmission..................................................57
7.1 Technology overview...............................................................................................57
7.1.1 Classification of wireless data transmission......................................................57
7.1.2 Data transmission of passive wireless sensors.................................................58
7.2 Existing wireless vehicle applications......................................................................60

IST-2001-34372 Page 3
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

7.3 Standards and regulations......................................................................................62
7.4 Trends.....................................................................................................................63
7.4.1 Wireless sensors using active radio communication.........................................63
7.4.2 Vehicle applications using active radio communication.....................................64
7.5 Conclusion ..............................................................................................................65
8. Basic Technologies for Batteryless Power Supply......................................................67
8.1 Introduction.............................................................................................................67
8.2 Inductive power transmission..................................................................................67
8.3 Power generation....................................................................................................73
8.3.1 Capacitive generator.........................................................................................74
8.3.2 Piezo generator.................................................................................................77
8.3.3 Summary...........................................................................................................80
8.4 Conclusion ..............................................................................................................81
9. Physical Properties of Tyre/Wheel System.................................................................82
9.1 Tyre attenuation at 434 MHz, 869 MHz, and 2.45 GHz...........................................82
9.2 Electromagnetic properties......................................................................................85
9.2.1 Introduction.......................................................................................................85
9.2.2 Measurement results of permittivity...................................................................85
9.2.3 Attenuation of magnetic field below 100 MHz...................................................89
10. Patent Overview .........................................................................................................92
10.1 Accelerometer and other sensors ...........................................................................93
10.2 Tyre integration.......................................................................................................93
10.3 Antenna...................................................................................................................95
10.4 Power transmission / generation.............................................................................96
10.5 General aspects of total system..............................................................................96
10.6 Conclusion ..............................................................................................................98
11. Abbreviations and References....................................................................................99

IST-2001-34372 Page 4
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

1. INTRODUCTION
Objectives
The objectives of the APOLLO project producing a prototype for an intelligent tyre/wheel system
are listed as follows:
1. To increase traffic safety by adding an intelligent tyre/wheel system to advanced vehicles
which provides data on the particular tyre and the given tyre-road contact.
2. To enable improvements for chassis/vehicle control systems, Advanced Driver Assistance
Systems (ADAS), and driver information.
3. To enable the introduction of innovative services concerning tyre and road conditions for
different user groups outside the vehicle.
The term “intelligent tyre/wheel system” does not literally mean that “intelligence” resides inside
the tyre/wheel system. The APOLLO project aims at making additional data from the tyre and the
tyre-road contact available at a communication interface on the vehicle.
The objectives are met by integrating innovative sensors into tyres and developing advanced
solutions for wireless data transmission and batteryless power supply. A mechatronic tyre/wheel
system is constructed by integrating all electronics into the tyre. [MAE02]

State of the art and potential technologies for intelligent tyre systems
The main goal of the APOLLO project is to increase traffic safety. To show the relevance of tyre
related risk factors in accident scenarios, an accident analysis was performed (Chapter 2). The
results with a more detailed description of the situation in the European countries Finland and
Germany are presented.
The basic technologies to be investigated in the APOLLO project are as follows:
• Sensor technology,
• Wireless data transmission and
• Batteryless power supply.

A crucial point of the state of the art study are sensors and sensor technologies (Chapter 4 - 6). In
this context, Tyre Pressure Monitoring Systems (TPMS) – the first products that have been
introduced in the market -, advanced tyre sensors and basic sensor technologies are described.
Already a TPMS contains more components than a single sensor. Therefore, important aspects of
system design and system integration into a tyre/wheel system can be derived by studying these
systems (Chapter 4). Some advanced tyre sensor systems, aiming e.g. at additional data on tyre
forces or friction information, are being developed since nearly 10 years, but products are not
available in the market yet. These sensor systems and the status of their development is presented
(Chapter 5). In addition, basic sensor technologies, that can be used for future developments of
intelligent tyre/wheel systems, are described, including the promising technology of capacitive
sensors (Chapter 6).

IST-2001-34372 Page 5
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

Key technologies for intelligent tyre/wheel systems are technologies for wireless data
transmission and batteryless power supply. Inductive transmission and radio transmission are the
basic technologies used for wireless data transmission (Chapter 7). Radio transmission is already
used for passive systems. There are a lot of developments and research activities utilising radio
transmission for active systems, too, but still the power consumption needed for this technology is
a big hurdle. Aspects of vehicle integration and frequency bands and regulations for short range
radio devices are described. Inductive transmission and power generation are basic technologies
for batteryless power supply of electronic systems. The principles of inductive power
transmission are described, and an overview is given on ongoing developments and research
activities on different methods of power generation technologies (Chapter 8). The ongoing
evolution and high innovation rate in these technology fields are a strong support for the future
product envisaged in the APOLLO project.
Constructing a mechatronic tyre/wheel system means the integration of electronics into the
tyre/wheel system. This mechatronic system has to operate properly in a vehicle environment
under all operating conditions. For the investigation and the selection of appropriate technologies
to be used for such a system it is necessary to know the basic electromagnetic properties of a
tyre/wheel system. Therefore, a pre-study was performed to measure these parameters
(Chapter 9). First measurements and simulations which are presented show promising results
indicating that the relevant frequency bands can be used to set up a mechatronic tyre/wheel
system.
It is not possible to give a complete overview on the subject of patent applications in the field of
intelligent tyre/wheel system, because of high and ongoing activities in this field. Therefore, only
important patent applications for key systems or key components are summarised (Chapter 10).
The state of the art study of sensors and the patent application overview show that there is still a
big gap between a lot of inventions and series products which are available on the market.
Therefore, it is worthwhile to pursue the approach of the APOLLO project where new
technologies are used for the development of an innovative tyre/wheel system which is suitable
for the vehicle environment including the production process, vehicle operation and product
recycling.

Overview
This document provides an overview on the state of the art of intelligent tyre systems and
potential technologies that can be utilised for sensors, wireless data transmission, and batteryless
power supply.
An accident analysis with an investigation of tyre-related risk factors shows the great benefit of
the envisaged system to improve traffic safety. This fits to visions and strategies of vehicle
manufacturers, automotive suppliers and tyre manufactures in respect to intelligent tyre/wheel
systems that are summarised.
The first products that have been introduced in the field of intelligent tyres are Tyre Pressure
Monitoring Systems (TPMS). Different system solutions for TPMS and activities of suppliers are
described. More sophisticated sensor systems, that are still in the process of research or pre-
development, show the high interest in this field. Basic sensor technologies which enhance the
realisation potential for innovative monitoring of tyre and tyre-road contact are presented.

IST-2001-34372 Page 6
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

Radio communication is a technology with a high potential for high performance wireless data
transmission. Applications for passive systems, trends towards radio transmission for active
systems, aspects of vehicle integration and standards are discussed. First investigations on
inductive transmission and power generation prove the potential of these technologies for the
development of a batteryless power supply.
Promising results of a pre-study, showing measurements of electromagnetic properties of the
tyre/wheel system, are presented.
An overview is given on selected patent applications for systems or key components of intelligent
tyre/wheel systems.
Following the approach of the APOLLO project is a promising perspective to achieve a
successful product for an intelligent tyre/wheel system which allows to expect over 4 000 saved
lives in all EU countries every year.

IST-2001-34372 Page 7
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

2. ACCIDENT ANALYSIS
2.1 INTRODUCTION
European Transport Safety Council’s (ETSC) general reports on EU fatalities illustrate that each
year 42 000 EU citizens are killed and over 3.5 million are injured in transport crashes. These
accidents cost over 166 billion Euros and are the leading cause of death and hospital admission
for citizens under 45 years. As shown in Figure 2.1-1 the number of deaths varies strongly in
ETSC member countries. This is partly due to differences in traffic volume, but also other reasons
can be seen. European-wide accident comparison is impossible, because the availability of
comparable in-depth data is limited. Compilation of statistics and accident related definitions
differ from one country to another. No representative statistical data are available on road traffic
accidents in Europe that are caused by a) tyre defects and b) accidents caused by drivers not
taking into account adverse road conditions. The following studies give, however, a good idea
that we are facing a severe safety problem caused either by defective tyres, adverse road
conditions or their combination. Finnish accident analysis shows that defective tyres were either a
contributing factor or a main cause in about 16 % of all fatal accidents. According to a report
from German Traffic Safety Committee, more than half of the accidents with personal injury are
caused by slippery tracks due to rain, ice and snow. Every year 40 people are killed in Germany
and over 2 000 are injured due to defective tyres only (German Traffic Safety Committee).
[HUT1]
For the accident analysis two European countries – Finland and Germany – are selected. Finland
represents a Nordic country with a long winter period. Germany represents a country with a high
traffic volume and density.

9000
8000
7000
6000
5000
4000
3000
2000
1000
0
F D I E K ) P B L A S K L N X
9
U 9 N D R FI U
9 I L
1
(
R
G

Figure 2.1-1: EU road deaths in 2000. Source: IRTAD, OECD, 2002 [HUT2]

IST-2001-34372 Page 8
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

2.2 FINLAND
The analysis is based on the reports of VALT (Finnish Motor Insurers’ Centre) and on the
investigation database of the Finnish Road Accident Investigation Teams, [HUT4]. The situation
in Finland is monitored by 21 teams having approximately 240 members in total. Every fatal road
accident is thoroughly investigated by these teams consisting of police-, vehicle engineering-,
traffic engineering-, doctor- and behavioural science- members. The lead-up to the accident, risk
factors, consequences and circumstances are documented into the album and electronic database.
By studying the figures and table presented below, it is evident, that tyre defects have a
significant role in fatal accidents. Their role is especially high in slippery and wet road conditions.
Defective tyres were either a contributing factor or a main cause in 16 % (483 accidents) of all
fatal accidents (2 980 accidents) in Finland in 1991 - 2001. In two out of three tyre related
accidents either worn-out tyres or tyres unfit for road conditions were a major contributory factor.
Under-inflated tyres were a risk factor in 12 % of tyre related accidents (see Figure 2.2-1).
Moreover, it is noteworthy that these figures do not include accidents where adverse road
conditions alone - even when tyres have been good - have been a contributory factor which is also
a target area for intelligent vehicle control systems.

TYRE RELATED RISK FACTORS IN FATAL ACCIDENTS IN 1991-
2001 (FINLAND)
Other tyre risksUnder-inflated tyres
5,73% 12,15%
Different tyre pressures
Worn-out tyres with
in tyres
studs
4,17%
19,79%
Worn-out tyres
18,75%
Tyres unfit for road
conditions
25,52% Tyres with different
Tyres unfit for the properties
vehicle 12,67%
1,22%
NOTE: TYRE RISK FACTOR WAS INVOLVED IN 483 ACCIDENTS, WHICH IS 16,2% OF ALL 2980

Figure 2.2-1: Tyre related risk factors by type of the tyre defect. [HUT3]

The effect of defective tyres varies strongly according to the road conditions. In snowy or icy
conditions the percentage of accidents, where tyre defect has had an effect is significantly high –

IST-2001-34372 Page 9
APOLLO Intelligent Tyre for Accident-free Traffic
Deliverable D7 Intelligent Tyre Systems – State of the Art and Potential Technologies
_____________________________________________________________________________

about 38 %. In these conditions, the most common deficiencies are the tyres unfit for road
conditions (about 15 %) and worn-out tyres with studs (about 14 %). In wet road conditions
defective tyres have been reported in 14 % of all accidents. The most important risk factor in wet
road conditions is worn-out tyres (about 8 %) (see Table 2.2-1).

Table 2.2-1: Tyre related risk factors by type of the defect and by road conditions. [HUT3]

TYRE DEFICIENCIES AS RISK FACTOR IN OCCUPANT-FATAL ACCIDENTS IN 1991-2001
(FINLAND)
ROAD SURFACE CONDITIONS
BARE, SNOWY
WET OTHER TOTAL
DRY OR ICY
RISK FACTORS OF TYRES N % 3) N % 3) N % 3) N % 3) N % 3)
Under-inflated tyres 1) 38 2,2 8 1,7 24 3,0 0 0,0 70 2,3
Different tyre pressures in tyres 1) 8 0,5 9 1,9 7 0,9 0 0,0 24 0,8
Worn-out tyres 1) 31 1,8 37 7,8 39 4,9 0 0,0 107 3,6
Tyres with different properties 1) 16 0,9 10 2,1 46 5,8 1 7,1 73 2,4
Tyres unfit for the vehicle 1) 3 0,2 1 0,2 3 0,4 0 0,0 7 0,2
Tyres unfit for road conditions 1) 9 0,5 17 3,6116 14,5 5 35,7 147 4,9
Worn-out tyres with studs 1) 3 0,2 2 0,4109 13,7 0 0,0 114 3,8
Other tyre risks 1) 14 0,8 3 0,6 15 1,9 1 7,1 33 1,1
TOTAL, ACCIDENTS INVOLVING TYRE DEFECT 2) 108 6,4 67 14,1302 37,8 6 42,9 483 16,2
TOTAL, ACCIDENTS INVESTIGATED 1692 100476 100798 10014 100 2980 100
1) Number of accidents involving risk factor in question
2) Number of accidents involving tyre related risk factors
3) Percentage of accidents investigated in the category

A more thorough investigation was made using the investigation database of the Finnish Road
Accident Investigation Teams. The objective was to study such fatal accidents which are
characterised by search parameters that are relevant for tyre monitoring and monitoring of tyre-
road contact, and based on this study to describe specific “accident scenarios” for later use in the
APOLLO project. These specific “accident scenarios” mean in this context accidents, which
possibly could be avoided by using an intelligent tyre/wheel system - the technical objective of
the APOLLO project.
In this study years 1998 - 2001 were chosen as a reference period. During this period 1 025 fatal
accidents were recorded (1998: 254, 1999: 261, 2000: 240 and 2001: 270). The main search
parameter was the loss of driving control. Other parameters (e.g. condition of tyres, abnormal
weather, road conditions, aquaplaning) varied in different searches. The percentage figure is
calculated in such a way that only accidents, where all marked search parameters are relevant, are
included (see Table 2.2-2).

IST-2001-34372 Page 10