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The ASSESS project is a collaborative project that develops test procedures for pre-crash safety systems like Automatic Emergency Braking (AEB). One key criterion for the effectiveness of e.g. AEB is reduction in collision speed compared to baseline scenarios without AEB. The speed reduction for a given system can only be determined in real world tests that will end with a collision. Soft targets that are crashable up to velocities of 80 km/h are state of the art for these assessments, but ordinary balloon cars are usually stationary targets. The ASSESS project goes one step further and defines scenarios with moving targets. These scenarios define vehicle speeds of up to 100 km/h, different collision scenarios and relative collision speeds of up to 80km/h. This paper describes the development of a propulsion system for a soft target that aims to be used with these demanding scenario specifications. The Federal Highway Research Institute- (BASt-) approach to move the target is a self-driving small cart. The cart is controlled either by a driver (open-loop control via remote-control) or by a computer (closed-loop control). Its weight is limited to achieve a good crashability without damages to the test vehicle. To the extent of our knowledge BASt- approach is unique in this field (other carts cannot move at such high velocities or are not crashable). This paper describes in detail the challenges and solutions that were found both for the mechanical construction and the implementation of the control and safety system. One example for the mechanical challenges is e.g. the position of the vehicle- center of gravity (CG). An optimum compromise had to be found between a low CG oriented to the front of the vehicle (good for driveability) and a high CG oriented to the rear of the vehicle (good for crashability). The soft target itself which is also developed within the ASSESS project will not be covered in detail as this is work of a project partner. Publications on this will follow. The paper also shows first test results, describes current limitations and gives an outlook. It is expected that the presented test tools for AEB and other pre-crash safety systems is introduced in the future into consumer testing (NCAP) as well as regulatory testing.
A flexible pedestrian legform impactor (FlexPLI) has been evaluated by a Technical Evaluation Group (Flex-TEG) of the Working Party on Passive Safety (GRSP) of the United Nations Economic Commission for Europe (UN-ECE). It will be implemented within phase 2 of the global technical regulation (GTR 9) as well as within a new ECE regulation on pedestrian safety as a test tool for the assessment of lower extremity injuries in lateral vehicle-to-pedestrian accidents (UN-ECE 2010-1, 2010-2 and 2010-3). Due to its biofidelic properties in the knee and tibia section, the FlexPLI is found to having an improved knee and tibia injury assessment ability when being compared to the current legislative test tool, the lower legform impactor developed by the Pedestrian Safety Working Group of the European Enhanced Vehicle-safety Committee (EEVC WG 17). However, due to a lack of biofidelity in terms of kinematics and loadings in the femur part of the FlexPLI, an appropriate assessment of femur injuries is still outstanding. The study described in this paper is aimed to close this gap. Impactor tests with the FlexPLI at different impact heights on three vehicle frontends with Sedan, SUV and FFV shape are performed and compared to tests with a modified FlexPLI with upper body mass. Full scale validation tests using a modified crash test dummy with attached FlexPLI that are carried out for the first time prove the more humanlike responses of the femur section with applied upper body mass. Apart from that they also show that the impact conditions described in the current technical provisions for tests with the FlexPLI don"t necessarily compensate the missing torso mass in terms of knee and tibia loadings either. Therefore it can be concluded that an applied upper body mass will contribute to a more biofidelic overall behavior of the legform and subsequently an improved injury assessment ability of all lower extremity injuries addressed by the FlexPLI. Nevertheless, the validity of the original as well as the modified legform for tests against vehicles with extraordinary high bumpers as well as flat front vehicles still needs to be evaluated in detail. A first clue is given by the application of an additional accelerometer to the legform.
Thoracic injury is one of the predominant types of severe injuries in frontal accidents. The assessment of the injury risk to the thorax in the current frontal impact test procedures is based on the uni-axial chest deflection measured in the dummy Hybrid III. Several studies have shown that criteria based on the linear chest potentiometer are not sensitive enough to distinguish between different restraint systems, and cannot indicate asymmetric chest loading, which has been shown to correlate to increased injury risk. Furthermore, the measurement is sensitive to belt position on the dummy chest. The objective of this study was to evaluate the optical multipoint chest deflection measurement system "RibEye" in frontal impact sled tests. Therefore the sensitivity of the RibEyesystem to different restraint system parameters was investigated. Furthermore, the issue of signal drop out at the 6 th rib was investigated in this study.A series of sled tests were conducted with the RibEye system in the Hybrid III 50%. The sled environment consisted of a rigid seat and a standard production three-point seat belt system. Rib deflections were recorded with the RibEye system and additionally with the standard chest potentiometer. The tests were carried out at crash pulses of two different velocities (30 km/h and 64 km/h). The tests were conducted with different belt routing to investigate the sensitivity of chest deflection measurements to belt position on the dummy chest. Furthermore, different restraint system parameters were investigated (force limiter level, with or without pretensioning) to evaluate if the RibEye measurements provide additional information to distinguish between restraint system configurations . The results showed that with the RibEye system it was possible to identify the effect of belt routing in more detail. The chest deflections measured with the standard chest potentiometer as well as the maximum deflection measured by RibEye allowed the distinction to be made between different force limiter levels. The RibEye system was also able to clearly show the asymmetric deflection of the rib cage due to belt loading. In some configurations, differences of more than 15 mm were observed between the left and side areas of the chest. Furthermore, the abdomen insert was identified as source of the problem of signal drop out at the 6th rib. Possible solutions are discussed. In conclusion, the RibEye system provided valuable additional information regarding the assessment of restraint systems. It has the potential to enable the evaluation of thoracic injury risk due to asymmetric loading. Further investigations with the RibEye should be extended to tests in a vehicle environment, which include a vehicle seat and other restraint system components such as an airbag.
Safety of light goods vehicles - findings from the German joint project of BASt, DEKRA, UDV and VDA
(2011)
Light goods vehicles (LGVs) are an important part of the vehicle fleet, providing a vital component in the European transportation system. On the other hand, LGVs are in the focus of public discussion regarding road safety. In order to analyse the accident situation of LGVs in an objective manner, Federal Highway Research Institute (BASt), VDA, DEKRA and German Insurers Accident Research (UDV) launched a joint project. The aim of this project, which will be finished by mid of 2011, is to identify reasonable measures which will further improve the safety of LGVs. For the first time, these partners jointly together conducted a research project and put together their know-how in accident research. Analyses are based on real-life accident data from the GIDAS database, the Accident Database of UDV (UDB), the DEKRA database and national statistics. The findings deliver answers to questions within the arena of future legislative actions and consumer protection activities. The analyses of databases cover areas of primary and secondary safety of LGVs with a special focus on advanced driver assistance systems (ADAS), driver behaviour as well as partner and occupant protection. Key figures from national statistics are used to highlight hotspots of accidents of LGVs in Germany. Finally, the proposed countermeasures are assessed regarding their potential effectiveness. Amongst others, the results show that the accident situation of LGVs is very similar to that of passenger cars. Noteworthy variations could be found in collisions with pedestrians, at reversing and regarding accident causes. Occupant safety of LGVs is on a higher level compared to cars. Results indicate that seatbelt use is on a significantly lower level compared to cars. This leads to higher-than-average injury risk for unbelted LGV occupants. When it comes to partner protection, there are problems with compatibility at LGVs. For car occupants there is a very high injury risk when colliding with a LGV. It indicates that higher passive safety test standards for LGVs would be counterproductive if they further increase stiffness of LGVs. The analysis of LGV-pedestrian accidents shows that pedestrian kinematic differs significantly from car-pedestrian accidents. At this point, existing pedestrian related test standards developed for cars cannot be adopted to LGVs. When it comes to active safety, ESC proved its effectiveness once again. Beyond that, rear view cameras, advanced emergency braking systems and lane departure warning systems show a safety potential, too. In addition to any technical countermeasures previously discussed, the importance of the driver behavior and attitude regarding the accident risk was investigated. In order to develop successful actions it is important to understand the main target population. In the case of LGV especially the crafts business and smaller companies are the major contributors the safety issue.
It is well known that most accidents with pedestrians are caused by the driver not being alert or misinterpreting the situation. For that reason advanced forward looking safety systems have a high potential to improve safety for this group of vulnerable road users. Active pedestrian protection systems combine reduction of impact speed by driver warning and/or autonomous braking with deployment of protective devices shortly before the imminent impact. According to the Euro NCAP roadmap the Autonomous Emergency Braking system tests for Pedestrians Protection will be set in force from 2016 onwards. Various projects and organisations in Europe are developing performance tests and assessment procedures as accompanying measures to the Euro NCAP initiative. To provide synthesised input to Euro NCAP so-called Harmonisation Platforms (HP-) have been established. Their main goal is to foster exchange of information on key subjects, thereby generating a clear overview of similarities and differences on the approaches chosen and, on that basis, recommend on future test procedures. In this paper activities of the Harmonisation Platform 2 on the development of Test Equipment are presented. For the testing targets that mimic humans different sensing technologies are required. A first set of specifications for pedestrian targets and the propulsion systems as collected by Harmonisation Platform 2 are presented together with a first evaluation for a number of available tools.
For a number of EU regulatory acts Virtual Testing (VT) is already allowed for type approval (see Commission Regulation No. 371/2010 of 16 April 2010 amending the Framework Directive 2007/46/EC). However, only a very general procedure on how to apply VT for type approval is provided. Technical details for specific regulatory acts are not given yet. The main objective of the European project IMVITER (IMplementation of VIrtual TEsting in Safety Regulations) was to promote the implementation of VT in safety regulations. When proposing VT procedures the new regulation was taken into account, in particular, addressing open issues. Special attention was paid to pedestrian protection as pilot cases. A key aspect for VT implementation is to demonstrate that the employed simulation models are reliable. This paper describes how the Verification and Validation (V&V) method defined by the American Society of Mechanical Engineers was adapted for pedestrian protection VT based assessment. or the certification of headform impactors an extensive study was performed at two laboratories to assess the variability in calibration tests and equivalent results from a set of simulation models. Based on these results a methodology is defined for certification of headform impactor simulation models. A similar study was also performed with one vehicle in the type approval test setup. Its bonnet was highly instrumented and subjected to 45 impacts in five different positions at two laboratories in order to obtain an estimation of the variability in the physical tests. An equivalent study was performed using stochastic simulation with a metamodel fed with observed variability in impact conditions of physical headforms. An estimation of the test method uncertainty was obtained and used in the definition of a validation corridor for simulation models. Validation metric and criteria were defined in cooperation with the ISO TC22 SC10 and SC12 WG4 "Virtual Testing". A complete validation procedure including different test setups, physical magnitudes and evaluation criteria is provided. A detailed procedural flowchart is developed for VT implementation in EC Regulation No 78/2009 based on a so called "Hybrid VT" approach, which combines real hardware based head impact tests and simulations. This detailed flowchart is shown and explained within this paper. Another important point within the virtual testing based procedures is the documentation of relevant information resulting from the verification and validation process of the numerical models used. For this purpose report templates were developed within the project. The proposed procedure fixes minimum V&V requirements for numerical models to be confidently used within the type-approval process. It is not intended to be a thorough guide on how to build such reliable models. Different modeling methodologies are therefore possible, according to particular OEM know-how. These requirements respond to a balance amongst the type-approval stakeholders interests. A cost-benefit analysis, which was also performed within the IMVITER project, supports this approach, showing the conditions in which VT implementation is beneficial. Based on the experience gained in the project and the background of the experts involved an outlook is given as a roadmap of VT implementation, identifying the most important milestones to be reached along the way to a future vehicle type approval procedure supported by VT. The results presented in this paper show an important step addressing open questions and fostering the future acceptance of virtual testing in pedestrian protection type approval procedures.
Since its beginning in 1999, the German In-Depth Accident Study (GIDAS) evolved into the presumably leading representative road traffic accident investigation in Europe, based on the work started in Hanover in 1973. The detailed and comprehensive description of traffic accidents forms an essential basis for vehicle safety research. Due to the ongoing extension of demands of researchers, there is a continuous progress in the techniques and systematic of accident investigation within GIDAS. This paper presents some of the most important developments over the last years. Primary vehicle safety systems are expected to have a significant and increasing influence on reducing accidents. GIDAS therefore began to include and collect active safety parameters as new variables from the year 2005 onwards. This will facilitate to assess the impact of present and future active safety measures. A new system to analyse causation factors of traffic accidents, called ACASS, was implemented in GIDAS in the year 2008. The whole process of data handling was optimised. Since 2005 the on-scene data acquisition is completely conducted with mobile tablet PCs. Comprehensive plausibility checks assure a high data quality. Multi-language codebooks are automatically generated from the database structure itself and interfaces ensure the connection to various database management systems. Members of the consortium can download database and codebook, and synchronize half a terabyte of photographic documentation through a secured online access. With the introduction of the AIS 2005 in the year 2006, some medical categorizations have been revised. To ensure the correct assignment of AIS codes to specific injuries an application based on a diagnostic dictionary was developed. Furthermore a coding tool for the AO classification was introduced. All these enhancements enable GIDAS to be up to date for future research questions.
A flexible pedestrian legform impactor (FlexPLI) with biofidelic characteristics is aimed to be implemented within global legislation on pedestrian protection. Therefore, it is being evaluated by a technical evaluation group (Flex-TEG) of GRSP with respect to its biofidelity, robustness, durability, usability and protection level (Zander, 2008). Previous studies at the Federal Highway Research Institute (BASt) and other laboratories already showed good progress concerning the general development, but also the need for further improvement and further research in various areas. An overview is provided of the different levels of development and all kinds of evaluation activities of the Flex-TEG, starting with the Polar II full scale pedestrian dummy as its origin and ending up with the latest legform impactor built level GTR that is expected to be finalized by the end of the year 2009. Using the latest built levels as a basis, gaps are revealed that should be closed by future developments, like the usage of an upper body mass (UBM), the validation of the femur loads, injury risk functions for the cruciate knee ligaments and an appropriate certification method. A recent study on an additional upper body mass being applied for the first time to the Flex-GT is used as means of validation of recently proposed modified impact conditions. Therefore, two test series on a modern vehicle front using an impactor with and without upper body mass are compared. A test series with the Flex-GTR will be used to study both the comparability of the impact behavior of the GT and GTR built level as well as the consistency of test results. Recommendations for implementation within legislation on pedestrian protection are made.
According to the German road traffic regulations children up to the age of 12 or a height below 150 cm have to use approved and appropriate child restraint systems (CRS). CRS must be approved according to UN-ECE Regulation No. 44. The regulation classifies CRS in 5 weight categories. The upper weight group is approved for children from 22 to 36 kg. However, studies show that already today many children weigh more than 36 kg although they have not reached a height of 150 cm. Therefore, no ECE R44 approved CRS is available for these overweight children. In conclusion, today's sizes and weights of children are no longer represented by the current version of the ECE R44. The heaviest used dummy (P10) weighs just 32.6 kg and has a height of 137.9 cm. Statistical data of German children show that already 5% of the children at a height of 137.9 cm have a weight above 45.3 kg. Regarding children at a height of 145 cm, the 95th percentile limit is at a weight of 53.3 kg. Based on these data 4 dummies with different heights and weights were defined and produced. Two of them are overweight. Up to now, there is no experience how current child restraint systems perform in a car crash if they are used by children with a weight above 36 kg and a height smaller than 150 cm. In the future, different child restraint systems will be tested with respect to the ECE R44 regulation using these overweight dummies.
The head impact of pedestrians in the windscreen area shows a high relevance in real-world accidents. Nevertheless, there are neither biomechanical limits nor elaborated testing procedures available. Furthermore, the development of deployable protection systems like pop-up bonnets or external airbags has made faster progress than the corresponding testing methods. New requirements which are currently not considered are taken into account within a research project of BASt and the EC funded APROSYS (Advanced PROtection SYStems) integrated project relating to passive pedestrian protection. Testing procedures for head impact in the windscreen area should address these new boundary conditions. The presented modular procedure combines the advantages of virtual testing, including full-scale multi-body and finite element simulations, as well as hardware testing containing impactor tests based on the existing procedures of EEVC WG 17. To meet the efforts of harmonization in legislation, it refers to the Global Technical Regulation of UNECE (GTR No. 9). The basis for this combined hardware and virtual testing procedure is a robust categorization covering all passenger cars and light commercial vehicles and defining the testing zone including the related kinematics. The virtual testing part supports also the choice of the impact points for the hardware test and determines head impact timing for testing deployable systems. The assessment of the neck rotation angle and sharp edge contact in the rear gap of pop-up bonnets is included. For the demonstration of this procedure, a hardware sedan shaped vehicle was modified by integrating an airbag system. In addition, tests with the Honda Polar-II Dummy were performed for an evaluation of the new testing procedure. Comparing these results, it was concluded that a combination of simulation and updated subsystem tests forms an important step towards enhanced future pedestrian safety systems considering the windscreen area and the deployable systems.