safety enhanced innovations for older road users … · issue date 31/08/2016 . deliverable 3.1b...
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SAFETY ENHANCED INNOVATIONS FOR OLDER ROAD USERS
EUROPEAN COMMISSION EIGHTH FRAMEWORK PROGRAMME
HORIZON 2020 GA No. 636136
This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 636136.
Deliverable No. D3.1B
Deliverable Title Design specifications for improved pedestrian tools
Dissemination Level Public
Written by
Lemmen, Paul Humanetics
Burleigh, Mark Humanetics
Oliver Zander BASt
Checked by Adria Ferrer IDIADA 31/08/2016
Approved by Wisch, Marcus BASt 31/08/2016
Issue date 31/08/2016
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EXECUTIVE SUMMARY This SENIORS deliverable report presents design requirements for improved pedestrian
impactors.
SENIORS WP3 will improve existing and develop new test tools for occupant and pedestrian
safety to represent the elderly during crash events. The elderly as a pedestrian / cyclist will
be addressed by adaptations to existing pedestrian impactors:
Adding an Upper Body Mass (UBM) to a legform impactor improving the biofidelity in
terms of kinematics and loadings of the lower extremities during impact.
Adding a neck – mass system to a headform impactor to result in a more realistic
rotational behavior and thus loading of the impactor
These updates are in line with previous proposals under the EU FP6 APROSYS project. Two
promising prototypes proposed in that project will be refined and further developed based on
biomechanical requirements defined in SENIORS WP2.
A full set of requirements related to anthropometry, biofidelity, durability, interfacing of
components with existing impactor parts, repeatability & reproducibility, handling, application
range etc. is provided in this report for both impactors. Based on this prototype tools will be
developed.
In addition to the legform and headform a thorax injury prediction tool will be explored in
SENIORS. A suitability investigation into options like the ES2 torso will be conducted. As no
detailed design is foreseen for this impactor device only brief info related to possible options
will be provided rather than a full overview of requirements.
Contributions of the partners:
HIS Co-ordination and main contributor to this the deliverable. Collection and
summary of requirements defined in WP1 and WP2. Defined requirements on
all other items including handling, instrumentation, interfaces with other parts,
durability.
BASt Contributed to all requirements and detailed review of report
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CONTENTS
Executive summary ........................................................................................................... 2
1 Introduction .............................................................................................................. 5
1.1 The EU Project SENIORS ................................................................................................ 5
1.2 Background to this Deliverable ..................................................................................... 6
1.3 Objectives of this Deliverable ....................................................................................... 7
1.4 Structure of this Deliverable ......................................................................................... 7
2 Conceptual Designs Proposed .................................................................................... 8
2.1 FlexPLI ......................................................................................................................... 8
2.2 Headform Impactor with Neck .................................................................................... 11
2.3 Thorax Impactor ......................................................................................................... 14
3 Industry needs and Seniors approach ....................................................................... 16
3.1 Injury patterns and biofidelity requirements ............................................................... 16
3.2 Durability and robustness ........................................................................................... 16
3.3 Handling / Usability .................................................................................................... 17
3.4 Repeatability & Reproducibility .................................................................................. 17
3.5 Sensitivity .................................................................................................................. 17
4 Biomechanical requirements ................................................................................... 19
5 Interfaces ................................................................................................................ 23
5.1 Flex PLI ...................................................................................................................... 23
5.2 Headform with neck ................................................................................................... 24
6 Application .............................................................................................................. 25
7 Durability ................................................................................................................ 26
8 Handling ................................................................................................................. 29
8.1 General ...................................................................................................................... 29
8.2 Flex PLI ...................................................................................................................... 29
8.3 Headform Impactor .................................................................................................... 29
9 Instrumentation ...................................................................................................... 30
9.1 FlexPLI UBM ............................................................................................................... 30
9.2 Headform impactor with neck .................................................................................... 30
10 Certification and calibration .................................................................................... 31
10.1 FlexPLI UBM ............................................................................................................... 31
10.2 Headform impactor with neck .................................................................................... 31
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11 Repeatability & Reproducibility ............................................................................... 32
11.1 Background ................................................................................................................ 32
11.2 Requirements FlexPLI UBM ......................................................................................... 32
11.3 Requirements Headform with Neck ............................................................................ 32
12 Sensitivity ............................................................................................................... 33
13 Summary and Conclusions ....................................................................................... 34
Glossary ......................................................................................................................... 36
References ...................................................................................................................... 37
Acknowledgments .......................................................................................................... 38
Disclaimer....................................................................................................................... 38
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1 INTRODUCTION
1.1 THE EU PROJECT SENIORS
Because society is aging demographically and obesity is becoming more prevalent, the
SENIORS (Safety ENhanced Innovations for Older Road userS) project aims to improve the
safe mobility of the elderly, and obese persons, using an integrated approach that covers the
main modes of transport as well as the specific requirements of this vulnerable road user
group.
This project will primarily investigate and assess the injury reduction in road traffic crashes
that can be achieved through innovative and suitable tools, test and assessment procedures,
as well as safety systems in the area of passive vehicle safety. The goal is to reduce, in near
future, the numbers of fatally and seriously injured older road users for both major groups:
car occupants and external road users (pedestrians, cyclists).
The SENIORS project consists of four technical Work Packages (WP1 – WP4) which interact
and will provide the substantial knowledge needed throughout the project. These WPs are:
WP1: Accidentology and behaviour of elderly in road traffic
WP2: Biomechanics
WP3: Test tool development
WP4: Current protection and impact of new safety systems
In addition, there is one Work Package assigned for the Dissemination and Exploitation
(WP5) as well as one Work Package for the Project Management (WP6).
The overall scope for the SENIORS project is shown in the Figure 1.
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Figure 1 Flowchart of the SENIORS project
1.2 BACKGROUND TO THIS DELIVERABLE
SENIORS WP3 will improve and develop test tools for occupant and VRU safety to represent
the elderly during crash events. The elderly as a pedestrian / cyclist will be addressed by
adaptations to existing pedestrian impactors:
Adding an Upper Body Mass (UBM) to a legform impactor
Adding a neck – mass system to a headform impactor
These items were identified and agreed upon in previous SENIORS WP2 meetings. The
updates will follow previous work done under the APROSYS project (e.g. Brüll et. Al., 2008;
Bovenkerk et. al. 2009).
In addition a thorax impactor device will be evaluated and tested in SENIORS. However for
this item existing dummy parts are expected to be used.
SENIORS WP3 is divided into three tasks:
Task 3.1 Design specifications: meant to define a full set of requirements for the test
tools to be developed.
Task 3.2 Tool designs: will realize test tools for occupant safety and pedestrian safety
based on the requirements defined under Task 3.1
Safety of older road users• Effectiveness of new tools and
advantages of new procedures• Applied to current and advanced
new safety systems• Passive• Active
Integrated benefit analysis
Biomechanical testingDummies / impactorsNumerical modelsInjury criteria
Injury risk curvesTest procedures
Assessment procedures
* To be confirmed from the accident analysis
‡ Head-neck and pedestrian thorax will be early-stage
research
Quantification of needs• Literature (injury, behaviour, …)• Accident studies
Initial benefit assessment• Achievable injury prevention• Analysis of risks• Derivation of safety strategies
Prioritise• Future project activities
PROJECT OVERVIEW
IDENTIFICATION OF NEEDS /
PRIORITIES FOR OLDER ROAD
USERS
IMPROVED TOOLS
CAR OCCUPANT
• Better older thorax IRC*
• Obese occupant• Active HBM
PEDESTRIAN/CYCLIST
• Flex-PLI with UBM• Head-neck• Pedestrian thorax‡
BENEFIT AND IMPACT
ASSESSMENTS
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Task 3.3 Tool Validations: evaluation of the produced parts by repeating tests
performed on PMHS, Human Body Model simulations or other testing using identical
conditions as specified in Task 2.1 defining the biofidelity requirements.
This report is the result of activities under Task 3.1.
1.3 OBJECTIVES OF THIS DELIVERABLE
Apart from the anthropometry and biofidelity needs as defined in WP1 and WP2,
requirements for instrumentation, sensitivity, repeatability, reproducibility and durability are
needed. This deliverable report presents a full set of specifications for the pedestrian safety
tools to be developed in WP3. Based on these specifications final concepts will be designed
in more detail and prototypes produced in Task 3.2.
Requirements relating to the obese occupant will be presented in deliverable report D3.1A.
1.4 STRUCTURE OF THIS DELIVERABLE
Chapter 2 presents the conceptual basis for the tools. The basic designs for the Flexible
Pedestrian Legform Impactor (FlexPLI) with Upper Body Mass (UBM) and headform
impactor with neck additions were already proposed in the APROSYS project. Some brief
background on the conceptual basis is provided. In addition this chapter provides some
background info on possible options for a thoracic impactor.
Chapter 3 provides an overview of industry and stakeholder needs. A generic overview of
needs is provided as basis to the specifications defined in the following sections.
Chapters 4 to 12 present the requirements related to anthropometry, biofidelity, durability,
handling, applications, instrumentation etc.
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2 CONCEPTUAL DESIGNS PROPOSED
2.1 FLEXPLI Studies in the APROSYS SP3 project showed that the presence of a so-called Upper Body
Mass representing pelvis and lower thorax results in better correlation between full dummy
and legform impactors (Bovenkerk et. al. 2009; Hardy 2009). Comparisons of Human Body
Model (HBM) simulations and impactor simulations as well as full dummy tests and impactor
tests showed that the overall motion of the impactor improves considerably when adding an
UBM. Other studies (Mallory et. al., 2008) also show the practicality of the UBM in tests on
high bumper vehicles for which the current FlexPLI design is less sensitive. Finally, the UBM
has been proposed as a potential solution to improvements on the bonnet leading edge test
(Hardy et. al., 2007).
In APROSYS an Upper Body Mass system was developed for the FlexPLI. The system was
realized on the so-called Flex-GT version which was the latest build at the time of
APROSYS. The design approach applied is outlined in Figure 2. A detailed description of
the development process including means of establishing parameters like mass, moment of
inertia etc. is provided in (Bovenkerk et. al., 2009).
Figure 2 UBM structure design process applied in APROSYS (Bovenkerk et. al., 2009)
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The resulting design is depicted in Figure 3 and Figure 4. The UBM assembly consists of an
upper plate which is the interface to the Flex-GTR, a slide rail and a mass. Simulation results
indicated the need for adjustable height and offset position of the mass to achieve better
correlation over a wider range of vehicle front ends. This was realized by a slide rail along
which two vertical positions of the mass can be fixed and a hole pattern in the upper plate
and base of slide rail which allows for two horizontal offset positions.
Figure 3 UBM Assembly and single components (Bovenkerk et. al., 2009)
Figure 4 Flex-GT UBM assembly. Installation on Flex-GT (top rows); mechanical parts (bottom row) and installation positions (columns) (Bovenkerk et. al., 2009)
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Figure 5 Upper structure of Flex-GT and components (Bovenkerk et. al., 2009)
The upper plate was directly connected to the upper block of the Flex-GT, see Figure 5.
Testing and simulations showed that the kinematics of the legform with the UBM were much
improved compared to the legform without the UBM and more humanlike (Hardy et al. 2009).
This was true for all vehicle shapes represented in the simulations with a lower bumper
reference (LBRL) higher than 460mm and even up to a LBRL of 620mm. The kinematics of
the legform with UBM were superior (more humanlike) than those achieved by raising the
standard legform by 75mm. The injury prediction capability of the legform with UBM was also
improved. Slightly greater knee bending angles were predicted than for the standard legform
but this is to be expected given the presence and constraining influence of the UBM. As
hardware testing was done only on a single vehicle it was indicated that additional testing is
needed. In particular it would be desirable to verify the performance of legform plus UBM in
real tests against high bumper vehicles in order to check its functionality and also to obtain a
validation of the mathematical model (Hardy et. al., 2009).
Since the ending of the APROSYS project FlexPLI has been updated from Flex-GT into the
FlexPLI-GTR to address various remarks from users world-wide and refinements needed for
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implementation in the Global Technical Regulation number 9 (GTR9). However, the principle
of attaching an UBM to the upper block is still applicable. On this basis it was decided in
WP2 meetings that the APROSYS prototype will form the basis for the developments in
SENIORS.
Items that will need further consideration / detailing include for instance:
Overall design principle: at the time of the APROSYS developments the influence of
the shape of the UBM was not clear. As described above a cylindrical mass rigidly
attached to the FlexPLI in four possible positions was developed. Task 2.5
simulations need to give insight if this design provides adequate kinematics for a wide
range of vehicle front ends and if it avoids interaction with the bonnet leading edge
during the biofidelic assessment interval of the legform impact. Alternatively, the
application of a flexible (e.g. rubber) element between FlexPLI and UBM could be
investigated towards an improved response.
Moment of Inertia (MoI): apart from the mass the MoI may have a large influence on
the response, in particular the bending of the femur. As such the MoI should be
regarded as a separate design parameter.
Simulation studies planned in SENIORS WP2 should provide the basis for the design
updates needed. The FlexPLI UBM design has been modelled by BASt (Methner et al.,
2012) and installed on the existing FlexPLI FE model. Simulation runs with Human Body
Models, original FlexPLI model and FlexPLI UBM model will be done on test rigs and modern
vehicle front ends to reveal response corridors and directions for updates.
2.2 HEADFORM IMPACTOR WITH NECK An improvement of the existing pedestrian headform impactor test was proposed in
APROSYS SP3 in order to better reproduce the human kinematics (Hardy et. al., 2009).
Studies regarding the dependency of the head-neck region on the rest of the body showed
that coupling of the head with the body should not be neglected, because angular
accelerations of the impactor could be extensive. However, this situation cannot be
represented by the spherical headform impactors as used up to date in regulations and
consumer test programmes world-wide. The improvement proposed in APROSYS SP3 was
considering the angular acceleration of a human head in addition to the linear acceleration
during the accident, and as such it reflected the coupling of the head with the rest of the
body.
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Figure 6 Design 1 – impactor with Hybrid III neck (left) and Design 2 - impactor with stiff neck (right). Design parameters considered in simulation studies indicated (Brüll
et. al., 2009)
Studies showed that an additional mass connected to the original headform with a certain
joint characteristics can significantly improve the impactor kinematics and thus contribute to
more realistic loadings especially of the angular acceleration. Two options were considered
(Brüll et al., 2008):
Design 1: Flexible connection using HIII 50th neck
Design 2: Rigid neck by metal connection
An investigation was made using pedestrian models, vehicles from five different classes, and
different velocities. Both the impactor models representing the HIII neck and the rigid
connection were parameterized in terms of (Brüll et. al. 2008):
Angle = 0° to 90°
Additional mass = 1 kg to 10 kg
Orientation of neck = 0° and 90°
Distance 1 = 0 mm to 100 mm
Distance 2 = 0 mm to ½ impactor
Distance 3 = 0 mm to 100 mm
Comparisons between Human Body Models and the parameterized headform models were
conducted. From these simulations it was observed that the angular acceleration, especially
the peak values, was represented much better with the improved concept. A design with the
Hybrid III neck between the impactor and an additional mass of 2.2 kg was found to give the
best results over the range of loading conditions considered. A prototype was produced by
modifying the necessary parts of the current impactor (Figure 7). This design concept will be
the basis for the SENIORS activities.
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Figure 7 Impactor with Hybrid III neck as developed in APROSYS (Brüll et. al., 2008) will form the basis for the SENIORS activities
Figure 8 Impactor test with the Hybrid III neck (Brüll et. al., 2008; Hardy et. al., 2009)
The addition of the neck required an update to the free motion headform (FMH) test bench. A
guidance system was realized for connecting the whole impactor (head impactor, neck, and
additional mass) to the test bench (Figure 8).
From the physical tests it was concluded that the improved impactor was able to better
realize the angular accelerations predicted in the human model simulations when using the
Hybrid III neck as the connection between the impactor and the additional mass. This
concept will therefore form the basis for the developments in the SENIORS project.
Requirements for further updates will follow from simulations planned in SENIORS WP2.
HBM and impactor simulations on various front ends will be conducted on the basis of which
response corridors will be defined and possible updates to the APROSYS design will be
checked.
It needs to be decided based on SENIORS WP2 simulation studies if only the 4.5 kg adult
headform impactor or both the 4.5 kg adult and the 3.5 kg child headform impactor will be
considered. Both impactors are used for testing according to the procedures described in for
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instance the UN ECE Regulation R127 (European Union, 2009) and the Euro NCAP
Pedestrian Testing Protocol (Euro NCAP, 2015). In relation to this decision it has to be noted
that regulations and consumer rating programmes do not always prescribe identical impact
velocities and impact angles. For instance, while Euro NCAP foresees headform tests to be
performed under impact angles of 65, 50 and 20 degrees at impact velocities of 40 km/h,
headform testing according to Regulation (EC) No. 78/2009 and UN-R 127 is realized under
impact angles of 65 and 50 degrees only at reduced impact speeds of 35 km/h. However,
APROSYS SP3 proposed to carry over the impact conditions which were the results of the
human body model simulations into the testing. As a result, individual impact conditions
could be used for each car class and pedestrian size. To avoid a large range of impactors it
was suggested combining certain pedestrian sizes. Therefore, a solution could be to
summarize average male (50th percentile male) and the large male (95th percentile male)
into one set of 4.5 kg headform tests while small females (5th percentile female) and children
(6 YO) could be combined into a 3.5 child/small adult headform test, which impacts on a
lower region of the bonnet.
Discussions are to be held in SENIORS WP2 to decide if both or either one of the impactors
will be considered. In both cases though the flexible neck design will form the starting point of
the activities. From the accident surveys under WP1 no clear guidance for priority setting
was obtained.
2.3 THORAX IMPACTOR As recent accident research using the German In-Depth Accident Study (GIDAS) Database
has shown, the relevance of injuries to the thorax in pedestrian accidents against modern
passenger cars has significantly increased in the last decade. During pedestrian accidents
against passenger cars registered in 2006 or later thoracic injuries signed responsible for
more than 17 percent of all AIS2+ injuries and almost 27 percent of all AIS3+ injuries to that
particular body region. Thus, injuries to the thorax are currently the most frequent pedestrian
AIS3+ injury location (Wisch et. al., 2014).
A first study to develop a test method for the evaluation of pedestrian impacts to the bonnet
leading edge of vehicles with a high front end geometry was done by Fredriksson et. al.
(2007). Due to the good measurement capabilities for the chest and the abdomen area and
field data showing a comparable injury distribution during near side car occupant and
pedestrian injuries it was concluded that side impact dummies could in principle be used for
the evaluation of injuries to the thorax of a pedestrian.
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Figure 9 ES-2 to SUV test setup (Fredriksson et. al., 2007)
As an alternative test tool for the evaluation of thoracic pedestrian injuries the use of the
pedestrian upper legform impactor needs be taken into account. While nowadays this
impactor is used for the evaluation of upper leg injuries, in previous testing protocols it was
used for the assessment of the protection potential of the bonnet leading edge and could
thus be used as an alternative tool for replication of thoracic injuries caused by that part of
the vehicle frontend. However, it remains questionable whether a correlation between femur
bending moments and maximum sum of forces as the injury criteria acquired by the upper
legform impactor and the compression of the chest and viscous criterion as injury criteria for
the thorax could be established. Therefore, in first instance, the applicability of the thorax of
the ES2 dummy for assessment of pedestrian thoracic injuries will be investigated further.
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3 INDUSTRY NEEDS AND SENIORS APPROACH
Industry needs on crash test dummy tools were previously defined in projects like THORAX
(Been et. al., 2010). As background and reference to the specifications defined in the next
chapters an overview of generic requirements is included below. Note that these “generic”
requirements are sometimes conflicting with SENIORS project requirements. In such case
SENIORS requirements will prevail.
3.1 INJURY PATTERNS AND BIOFIDELITY REQUIREMENTS
The tools should be able to reliably detect relevant injury patterns. For the development of
injury risk curves reference is often made to existing ISO-methods (ISO, 2014). However, in
the case of SENIORS research into new method using Human Body Models is proposed.
The test tools development under WP3 will follow this approach and rely on WP2 definitions
for the risk criteria.
Also biofidelity should be assessed according to the ISO proposals. However, again the
SENIORS approach is to investigate new methods including data generated using Human
Body Model simulations. The SENIORS Biofidelity requirements will be specified in two
reports:
• SENIORS Deliverable 2.1 includes the more traditional approach referring to existing
data
• SENIORS Deliverable 2.5 Includes response corridors generated using Human Body
Model simulations.
3.2 DURABILITY AND ROBUSTNESS Given the fact that the FlexPLI has been recently introduced within the Euro NCAP protocol
and UN Regulation it is not to be expected that vehicle front end designs will change
significantly over the next years. As such it is not foreseen that vehicle changes are
introduced which result in different loading conditions on the impactors. On the other hand if
the impactors are changed adding additional weight (FlexPLI and headform) and inertia
these additions may introduce significant loadings in some parts of the impactors like for
instance the femur bone in the FlexPLI. Nonetheless, general durability and robustness
requirements from industry and stakeholders like Euro NCAP are to be followed:
• Certification intervals should not change compared to current tools;
• Life expectancy similar to existing tools (with moderate demand for spare parts) or
longer;
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• Impactors should withstand a wide range of loads resulting from impacts on current
test areas as well as extended areas like the outermost points of the bumper area;
• No damage of the impactors if the injury thresholds are exceeded (up to a value of
150% of injury values).
3.3 HANDLING / USABILITY When applying vrash test dummies and pedestrian impactors the following operational or
handling requirements generally apply:
• Design should be user-friendly;
• Easy positioning and handling laboratory environment;
• Easy change of impactor and sensors, even on the crash track.
3.4 REPEATABILITY & REPRODUCIBILITY In order to ensure that repeated tests with either the same or with two identical impactors
provide identical results the tools developed should be repeatable and reproducible.
Repeatable means that repeated tests with the same impactor give identical results whereas
reproducible means that repeated tests with two identical impactors gives the same results.
In general the following requirements exists for crash test dummies and pedestrian
impactors:
• The Coefficient of Variation on injury parameter measurement shall be within ± 5%
variation: CV<±5%;
• When defining certification tests the loading introduced should be in the range to be
expected in actual tests;
• The width of the certification corridors have to be within the range of the current ones;
• The impactor responses should be non-sensitive against environmental influences
(e.g. temperature, humidity, etc.);
• The variances of the impactor responses should be no greater than the ones shown
with the FlexPLI.
Note: The requirement of CV< ±5% is more demanding than in generally accepted dummy
standards. Meeting this requirement may not be possible by applying standard production
tolerances. More narrow certification corridors may be feasible, but at a cost, for instance by
additional testing and parts selection.
3.5 SENSITIVITY The sensitivity of an impactor relates to the capability of the tool to identify differences
between designs of the vehicle front end. In other words the measured response should be
sensitive to the design and identify good and bad designs. In general the following
requirement applies:
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• Capability to distinguish different front ends: good – acceptable – poor. Here the
indication good – acceptable – poor is based on performance with existing tools and /
or Human Body Model simulations.
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4 BIOMECHANICAL REQUIREMENTS
In SENIORS Task 2.1 “Biomechanical requirements” a literature review of existing
biomechanical data for pedestrian safety tools was conducted. Although various papers and
background articles can be found in literature none of these included biomechanical data
sets or information that provides test conditions and corresponding response corridors which
could serve as requirements for the updates to the existing impactors.
As an example of a paper presenting test results that include response data Zander et. al.
(2011) can be listed. The paper presents test results for a FlexPLI mounted on a HII dummy,
see Figure 10. Full scale impact tests against a sedan, SUV and FFV type of vehicle were
conducted. Some results are depicted in Figure 11 through Figure 14. The figures include
comparisons of the FlexPLI mounted on the HII against FlexPLI only and FlexPLI with UBM
tests. It is clear that the FlexPLI with UBM has a superior performance over the FlexPLI
when looking at these data.
Figure 10 FlexPLI mounted on HII pelvis and test on sedan (Zander et. al., 2011)
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Figure 11 Results for tests of FlexPLI mounted on HII against SEDAN type of vehicle (Zander et. al., 2011)
Figure 12 FlexPLI mounted on HII versus SUV test (Zander et. al., 2011)
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Figure 13 Comparison of kinematics in tests with UBM and HII dummy against SUV (Zander et. al., 2011)
Figure 14 Comparison of kinematics in tests with UBM and HII dummy against SUV (Zander et. al., 2011)
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Although the test data presented above are valuable for comparison purposes it needs to be
extended towards a broader range of vehicle front geometries and impact conditions in order
to form a biomechanical basis for the development of a FlexPLI with applied UBM. For this
purpose test conditions and human response data are needed. Since such data is not
available it was decided that biomechanical response corridors will be established by
simulations with Human Body Models in Task 2.5. An extensive simulation matrix has been
defined considering different HBM’s and vehicle front-ends. Also generic test set-ups are
being considered, allowing for future comparison with hardware tests. The results of these
simulation efforts will be included in D2.5B Updated injury criteria for pedestrian test tools
which is expected by M26. Intermediate results for design purposes are to be expected by
October 2016. It should be noted that FlexPLI and headform impactor models will be updated
to include proposed modifications. On this basis feasibility of meeting response corridors will
be investigated and refinements to the design may be identified.
Existing requirements on both the existing FlexPLI and the headform impactors will be
maintained. This implies that any changes done on the FlexPLI design or to the headform
impactors should be validated against the requirements previously set for these tools.
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5 INTERFACES
5.1 FLEX PLI The Upper Body Mass developed will interface with the upper end of the current FlexPLI. It is
expected that the interface between FlexPLI and UBM is realized by an element replacing
the end cover (item 17 in Figure 15 below) which directly links to the Upper Block (item 16 in
Figure 15 below). This approach was also applied in the APROSYS project. Some detailing
or maybe an intermediate element between UBM and Upper Block is foreseen though to
stabilize the connection.
As far as sensors are concerned: it is intended to have additional sensors that will be
installed on the UBM and that are linked to the existing on board Data Acquisition Systems
system in the FlexPLI.
Figure 15 Femur Assembly, Exploded View (Humanetics, 2015)
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5.2 HEADFORM WITH NECK In line with previous developments under the APROSYS project the update to the existing
headform is expected to be a neck–mass system connected to the impactor through a
bracket. The bracket can be installed on the end plate (for example item D.GC in the 3.5 kg
JNCAP/ECE headform impactor shown in Figure 16). This may require addition of a hole
pattern which is easily realized in the existing parts.
Unlike the FlexPLI UBM additional sensors needed to the neck–mass added to the headform
will not be linked to any on board DAS system in the impactor itself. Given the limited space
and influence on mass and inertia this is not recommended.
Figure 16 JNCAP/ECE 3.5 KG Head form Impactor (Humanetics, 2015)
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6 APPLICATION
Both test tools, the Flex PLI with applied upper body mass and the head extended with neck
shall be suitable for existing pedestrian impactor test conditions described in Commission
Regulation (EC) No. 631/2009 (EC, 2009) and the Euro NCAP pedestrian testing protocol
(Euro NCAP, 2016).
The applicability of the impacted areas is expected to be significantly improved using the
updated tools due to certain limitations of the existing impactors. This may include for
instance Flex PLI UBM impacts on extensively angled areas.
The applicability of the FlexPLI UBM device for replacing upper legform tests according to
the latest Euro NCAP protocol will be considered as well.
Also the tool might be applied in tests on high bumper vehicles.
In any case the tools developed should be suitable to withstand loadings in biomechanical
test conditions developed and defined in Task 2.5.
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7 DURABILITY
The impactors developed shall be able to withstand minimum of 10 tests not exceeding
150% of injury criteria without permanent deformation or failure of parts. Cables and other
vulnerable equipment shall be well protected.
Figure 18 to Figure 22 compare test results for the Flex-GT and the Flex-GT with UBM for
tests depicted in Figure 17. Adding UBM components results in a substantial increase in
femur and tibia moments as well as the ligament elongations. For some of the signals results
almost double. Such doublings are to be anticipated for the FlexPLI with UBM developed in
the SENIORS project. Alongside with an improved biofidelity of the FlexPLI it is
recommended that high loadings on parts are avoided by mechanical limiters. In the legs this
might be achieved by reducing the play in the bone overload wires. The overload wires must
not restrict the bones in the injury range. In the knee, plastic protrusions on interface can be
removed in the current design to help avoid damage and wire ligaments may need
strengthening. An overload limiter could also be applied by changing ligament spring stop
height.
Figure 17 Test set-up Flex-GT UBM and impact location #1 (middle) and #2 (right) s (Bovenkerk et. al., 2009)
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Figure 18 Femur and tibia histories for tests at impact location #2 Flex-GT standard (left) and Flex-GT with UBM (right) (Bovenkerk et. al., 2009)
Figure 19 Summary of Femur (left) and tibia (right) bending moment results for tests at impact location #1 (Bovenkerk et. al., 2009)
Figure 20 Summary of Femur (left) and tibia (right) bending moment results for tests at impact location #2 (Bovenkerk et. al., 2009)
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Figure 21 Ligament histories for tests at impact location #2 Flex-GT standard (left) and Flex-GT with UBM (right) (Bovenkerk et. al., 2009)
Figure 22 Knee ligament elongation results at location #1 (left) and #2 (right) (Bovenkerk et. al., 2009)
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8 HANDLING
8.1 GENERAL Parts needed to update both the FlexPLI and the headform impactors should be easily
available and proven in practice. Also updated tools should be able to be used with existing
current propulsion systems. As such it is recommended to avoid significant masses to be
added which exceed the capacity of existing launchers. Adjustments to launching plates and
fixtures are to be expected though.
The designs will be entirely metric, using metric threads and fasteners throughout the tools.
All documentation will be in SI units, using mm for dimensions, kg for mass, Newton for
force. All instrumentation will be metric.
8.2 FLEX PLI The Upper Body Mass assembly will be designed with easy but stable and accurate
mounting to the Flex PLI. In case the vertical position of the mass is required to be variable
an easy, click-stop type, positioning mechanism will be implemented. This will allow for quick
and repeatable positioning and reducing the risks of error due to mistakes.
The existing release hook concept for firing will be used or modified to handle the additional
weight. In case of design changes same functionality will be maintained.
Additional sensors, like accelerometers and Angular Rate Sensors (ARS (ARS) sensors, on
the upper body mass will be fully integrated and linked to the on board DAS systems.
A launcher plate for stable firing of the impactor will be developed or adjustments made to
existing launcher plate(s).
8.3 HEADFORM IMPACTOR The headform impactors will be designed with existing components like HIII 50th or HIII 5th
neck and machined parts. This ensures availability of parts and reduces costs.
As far as the addition of sensors, like accelerometers and ARS sensors on the mass, it is not
foreseen to integrate the channels on any on board DAS systems in existing headform
impactors. Hence such channels will be dealt with using off board DAS. Reason being the
limited spacing available in the headform impactor itself.
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9 INSTRUMENTATION
9.1 FLEXPLI UBM The device’s instrumentation would be that required for the standard bumper test with
possible additions of:
A load cell at the hip joint
Pelvis accelerometers and ARS sensors in 3 directions to monitor motions
Transducers to measure femur bending which are already installed in the FlexPLI
Given the fact that the UBM is designed as a rigid mass it will be very difficult to include any
pelvis injuries in the tool. Accelerometers could be installed but this does not provide a link to
injury mechanisms like pelvic bone fractures.
9.2 HEADFORM IMPACTOR WITH NECK The device’s instrumentation would be that required for the standard bonnet impact tests with
possible additions of:
Accelerometers and ARS sensors in three directions installed on the mass to monitor motions
The ARS sensors may be used to serve as input to rotational head injuries listed in
SENIORS D2.1. However, in respect to this it needs to be indicated that the existing
rotational head injury criteria are under intense debate and any application to pedestrian
safety would need solid biomechanical research.
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10 CERTIFICATION AND CALIBRATION
10.1 FLEXPLI UBM Updates foreseen to the FlexPLI consist of a mass connected to the upper part through a
rigid link or flexible joint. In addition updates to mechanical limiters are foreseen to avoid
overload on parts like femur bone and ligaments. Given these updates it is foreseen that the
FlexPLI certification test setup will remain identical to the existing set. Inverse impactor tests
of FlexPLI with UBM are foreseen.
A check on the weight and Center of Gravity (CoG) is added for the UBM parts. Such a
check is considered sufficient for these rigid parts.
10.2 HEADFORM IMPACTOR WITH NECK Updates foreseen to the headform impactor consist of an existing HIII 50th or HIII 5th dummy
neck and a mass. It is recommended to have the neck certified according to existing
procedures for the HIII 50th or HIII 5th dummy, hence pendulum tests. The rigid mass added
needs to be checked on correct weight and CoG.
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11 REPEATABILITY & REPRODUCIBILITY
11.1 BACKGROUND The repeatability and reproducibility of the impactors will be assessed by testing in a well-
controlled condition with the optimum control of test parameters. Normally certification tests
are used for this purpose as car testing conditions are not so well controlled in comparison.
Repeatability is assessed by repeating at least six tests on one and the same impactor
(component). Reproducibility is normally assessed by repeating one test on at least six
different impactors of the same design and build level. However, as SENIORS will deliver
two impactors of each type only the reproducibility is most likely to be analysed on these
impactors.
Repeatability and reproducibility are expressed in the coefficient of variation (CV). The CV is
calculated by the standard deviation of at least six test results divided by the average of the
same set of test results. As the CV is expressed in %, the outcome is multiplied by 100.
11.2 REQUIREMENTS FLEXPLI UBM The repeatability of the Flex PLI UBM shall be CV < ±5% on injury assessment and
calibration signals.
The reproducibility of the Flex PLI UBM is targeted to be CV < ±5% on injury assessment
and calibration signals. However, based on experience with the existing FlexPLI it is known
that this requirement is very difficult to meet.
11.3 REQUIREMENTS HEADFORM WITH NECK The repeatability of the headform with neck shall be CV < ±5% on injury assessment and
calibration signals.
The reproducibility of the headform with neck is targeted to be CV < ±5% on injury
assessment and calibration signals. However, based on existing testing experience with
standard headforms it is known that this requirement is very difficult to meet.
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12 SENSITIVITY
The design of the SENIORS test tools will be such that the tools are sensitive to variations in
vehicle front ends that change the probability of serious injuries to pedestrians. In other
words, the results of variation of impactor loadings should result from the particular safety
performance provided by vehicle frontends to be assessed while ambient test conditions
such as temperature and humidity need to be stabilized in order to avoid influence on test
results. The impactors will, however, not show excessive sensitivity to variations in
environmental conditions likely to occur in different test environments, nor to small changes
in loading conditions.
The operation temperature of the impactors, the test facility and the vehicle or vehicle sub
system to be tested shall be between 16 and 24° C. The test facility and the vehicle or
vehicle sub system shall have a relative humidity of 40 per cent ± 30 per cent.
A test tool is sensitive to a certain loading condition when there is a significant increase
(sometimes decrease) of output to increased loading (input) of the tool. However, the ability
to discriminate between higher and lower safety performance is at risk when the test results
show large scatter. The impactors should therefore not only be sensitive, but also be able to
discriminate between a bad performing vehicle front end and a good performing vehicle front
end. In order to assess the discriminative ability of the impactors it should ideally be tested at
the lower end of the input domain (good protective system) and at the higher end of the input
domain (poor protective system). The lower input load should be defined at a low injury risk,
(e.g. Euro NCAP upper performance limit) and the higher input load should be defined at a
higher injury risk, e.g. legal injury tolerance or Euro NCAP lower performance limit. However,
finding vehicle front-ends in this range is laborious and testing is costly so most likely this
approach is not feasible within SENIORS.
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13 SUMMARY AND CONCLUSIONS The present deliverable provides design specifications for improved pedestrian tools towards
a better protection of head and lower extremities of vulnerable roads users in case of being
impacted by passenger cars.
By adding a pedestrian torso mass to the flexible pedestrian legform impactor (FlexPLI) the
tool is being improved towards its kinematics and induced loadings for a better injury
assessment ability for knee and tibia injuries especially in case of accidents with high bumper
vehicles, but also with sedan and flat front shaped vehicles. In addition, for the first time it is
possible to assess femur injuries at the same time and with the same tool, replacing the
upper legform impactor that has been previously used for the assessment of the protection
potential of the bonnet leading edge on the one hand, and for assessing femur injuries in
case of high bumper vehicles on the other hand. Besides, it can be expected that the
kinematics of the FlexPLI being significantly improved when testing angled areas on the
bumper, giving more realistic test results at the outer ends of the bumper test area.
A modification of the ISO headform impactors (adult and child), applying the neck of the 50th
HIII male and 5th HIII female is expected to significantly raise the biofidelity in terms of
kinematics as well as head loadings by limitation of the rotation of the impactor.
The influence of both, adding an upper body mass to the FlexPLI and applying a neck-mass
to the ISO headforms, is being examined in Task 2.5 where the kinematics and loadings
correlation between the modified impactors and human body models are studied in detail.
Fine tuning of these impactors will give input to the further impactor designs that will be
realized.
Alongside with an improved biofidelity regarding kinematics and loadings, repeatability and
reproducibility it is expected to remain at least at the same level as today. This will ensure a
robust introduction giving reliable results within legislation as well as consumer testing
programmes.
As accident research has shown that pedestrian thorax injuries frequently occurring during
accidents with passenger cars, a test tool reflecting those injuries is aimed at to be
developed. However, at this point in time it can be expected to either decouple a part of the
thorax from the ES-2 dummy or find a correlation between the pedestrian upper legform
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impactor and the pedestrian thorax. The applicability of this method needs to be further
examined.
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GLOSSARY
Term Definition
APROSYS Advanced Protection Systems; Large scale EU FP5 project
ARS Angular Rate Sensor
ACL Anterior Cruciate Ligament; part of the structure of the knee
ATD Anthropometric test device; sometimes known as a crash test dummy
BASt Bundesanstalt für Straßenwesen
CAE Computer Aided Engineering
CoG Center of Gravity
FE Finite Element; a type of numerical modelling
FlexPLI Flexible Pedestrian Legform Impactor
FMH Fre Motion Headform
HBM Human Body Model
HNI Head-neck impactor
ISO International Organization for Standardization
LMU Ludwig-Maximilians-Universität
MCL Medial Collateral Ligament
NRF Number of rib fractures
PCL Posterior Cruciate Ligament; part of the structure of the knee
PMHS Post Mortem Human Subject
SENIORS Safety ENhanced Innovations for Older Road userS
THUMS Total HUman Model for Safety; an HBM developed by Toyota
TRL Transport Research Laboratory
UBM Upper Body Mass
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REFERENCES Been B, Borthenschlager K, Steeger B (2010). „Design Specification For Demonstrator Development.” THORAX Deliverable Report D3.1. Brüll S, Bovenkerk J (2008). “New and improved test methods to address head impacts.” APROSYS Deliverable Report D3.3.3C. Bovenkerk J, Zander O (2009). “Evaluation of the extended scope for FlexPLI obtained by adding an upper body mass.” APROSYS Deliverable Report D3.3.3H. European New Car Assessment Programme (2015). “Pedestrian Testing Protocol Version 8.2”. Euro NCAP, November 2015.
European Union (2009). “COMMISSION REGULATION (EC) No 631/2009 of 22 July 2009 laying down detailed rules for the implementation of Annex I to Regulation (EC) No 78/2009 of the European Parliament and of the Council on the type-approval of motor vehicles with regard to the protection of pedestrians and other vulnerable road users, amending Directive 2007/46/EC and repealing Directives 2003/102/EC and 2005/66/EC.” Official Journal of the European Union, 25 July 2009. Fredriksson R, Flink E, Boström O, Beckman K (2007). „Injury mitigation in SUV-to-pedestrian impacts.“ ESV Conference Paper number 07-0380. Hardy R (2009). “Final report for the work on Pedestrian and Pedal Cyclist Accidents (SP3).” APROSYS Deliverable Report AP-90-0003. Hardy B, Lawrence G, Knight I, Simmons I, Carroll J, Coley G, Bartlett R (2007). “A study of possible future developments of methods to protect pedestrians and other vulnerable road users.” Report under EC Contract No. ENTR/05/17.01. Humanetics (2015). Flex PLI GTR User’s Manual. Humanetics (2015). D.G 3.5 KG JNCAP/ECE Pedestrian Head Form Impactor User’s Manual Hynd D, Hylands N, Wagner A, Zander O, Eggers A, Ott J, Wisch M (2016). “Biofidelity Requirements for an Older Car Occupant and External Road User Surrogate.” SENIORS Deliverable Report D2.1. ISO (2014), Procedure to construct injury risk curves for the evaluation of road user protection in crash tests. ISO Technical Standard 18506 Mallory A, Stammen J (2008). Design of a Proposed Upper Body Mass (UBM). www.unece.org/trans/main/wp29/wp29wgs/wp29grsp/pedestrian_FlexPLI.html Wisch M, Zander O (2015). „Radfahrer-Pkw-Unfälle”. Annual Report 2013/2014 of the Federal Highway Research Institute (BASt). Document A 37. Zander O, Gehring DU, Lessmann P (2011). „Improved Assessment Methods of Lower Extremity Injuries in Vehicle to Pedestrain Accidents using Impactor Tests and Full-Scale Dummy Tests.” ESV Conference Paper number 11-0079.
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Zander O (2012). “Refinement of Corridors for FlexPLI Dynamic Assembly Certification Tests.” 4th Meeting of GRSP IG GTR9-PH2 Task Force Review and Update Certification Corridors (TF-RUCC). Document TF-RUCC-4-04.
ACKNOWLEDGMENTS
This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 636136.
DISCLAIMER This publication has been produced by the SENIORS project, which is funded under the Horizon 2020 Programme of the European Commission. The present document is a draft and has not been approved. The content of this report does not reflect the official opinion of the European Union. Responsibility for the information and views expressed therein lies entirely with the authors.