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Video

Challenges in Automotive Electrification and Powertrain Component Development

2011-11-07
An overview of Daimler?s progression to advance powertrain technology in a growth industry shows many different solutions to improvement in transportation. Daimler continues to make breakthroughs in technology development and application building on 125 years of automotive development. Optimization of current powertrains will enable a significant gain in CO2/mi reductions, that dependent on product mix can be augmented with additional technologies. There is however no bypass to some form of electrification, enabling efficiency gains and alternative forms of power supply. Development of hybrid powertrains continues in an established manner and enhanced development of further electrified powertrains are in development. Organizationally and technically, significant skills and adjustments need to continue to be undertaken enabling OEMs and in particular the supply base to develop optimized solutions efficiently. The outlook is bright for novel component development and innovation.
Technical Paper

Daimler Aeroacoustic Wind Tunnel: 5 Years of Operational Experience and Recent Improvements

2018-09-24
2018-01-5038
Since 2013 the new Daimler Aeroacoustic Wind Tunnel (AAWT) is in operation at the Mercedes-Benz Technology Center in Sindelfingen, Germany. This construction was the second stage of a wind tunnel center project, which was launched in 2007 and started with the climatic wind tunnels including workshop and office areas. The AAWT features a test facility for full-scale cars and vans with a nozzle exit area of 28 m2, a five-belt system, and underfloor balance to measure forces with best possible road simulation. With a remarkable low background noise level of the wind tunnel, vehicle acoustics can be investigated under excellent conditions using high-performance measurement systems. An overview is given about the building and the design features of the wind tunnel layout. The aerodynamic and aeroacoustic properties are summarized. During the first years of operation, further improvements regarding the wind tunnel background noise and vehicle handling were made.
Technical Paper

Finding All Potential Run-Time Errors and Data Races in Automotive Software

2017-03-28
2017-01-0054
Safety-critical embedded software has to satisfy stringent quality requirements. All contemporary safety standards require evidence that no data races and no critical run-time errors occur, such as invalid pointer accesses, buffer overflows, or arithmetic overflows. Such errors can cause software crashes, invalidate separation mechanisms in mixed-criticality software, and are a frequent cause of errors in concurrent and multi-core applications. The static analyzer Astrée has been extended to soundly and automatically analyze concurrent software. This novel extension employs a scalable abstraction which covers all possible thread interleavings, and reports all potential run-time errors, data races, deadlocks, and lock/unlock problems. When the analyzer does not report any alarm, the program is proven free from those classes of errors. Dedicated support for ARINC 653 and OSEK/AUTOSAR enables a fully automatic OS-aware analysis.
Technical Paper

Implementation of an Open-Loop Controller to Design the Longitudinal Vehicle Dynamics in Passenger Cars

2017-03-28
2017-01-1107
In order to offer a wide range of driving experiences to their customers, original equipment manufacturers implement different driving programs. The driver is capable of manually switching between these programs which alter drivability parameters in the engine control unit. As a result, acceleration forces and gradients are modified, changing the perceived driving experience. Nowadays, drivability is calibrated iteratively through road testing. Hence, the resulting set of parameters incorporated within the engine control unit is strongly dependent on the individual sentiments and decisions of the test engineers. It is shown, that implementing a set of objective criteria offers a way to reduce the influences of personal preferences and sentiments in the drivability calibration process. In combination with the expertise of the test engineers, the desired vehicle behavior can be formalized into a transient set point sequence to give final shape to the acceleration behavior.
Technical Paper

Improved Full Vehicle Finite Element Tire Road Noise Prediction

2017-06-05
2017-01-1901
This paper presents the application to full vehicle finite element simulation of a steady state rolling tire/wheel/cavity finite element model developed in previous work and validated at the subsystem level. Its originality consists in presenting validation results not only for a wheel on a test bench, but for a full vehicle on the road. The excitation is based on measured road data. Two methods are considered: enforced displacement on the patch centerline and enforced displacement on a 2D patch mesh. Finally the importance of taking the rotation of the tire into account is highlighted. Numerical results and test track measurements are compared in the 20-300 Hz frequency range showing good agreement for wheel hub vibration as well as for acoustic pressure at the occupant’s ears.
Journal Article

Investigation of Tire-Road Noise with Respect to Road Induced Wheel Forces and Radiated Airborne Noise

2014-06-30
2014-01-2075
Low interior noise levels in combination with a comfortable sound is an important task for passenger cars. Due to the reduction of many noise sources over the last decades, nowadays tire-road noise has become one of the dominant sources for the interior noise. Especially for manufactures of luxury cars, the reduction of tire-road noise is a big challenge and therefore a central part of NVH development. The knowledge of the noise transmission behavior based on the characteristics of the relevant sources is a fundamental of a modern NVH - development process. For tire-road noise the source characteristics can be described by wheel forces and radiated airborne noise. In combination with the related vehicle transfer functions it is possible to describe the noise transmission behavior in detail. A method for estimating wheel forces and radiated airborne noise is presented.
Technical Paper

The Truck of the Future: Autonomous and Connected Driving at Daimler Trucks

2017-05-10
2017-01-1931
Due to the continuous increasing highway transport and the decreasing investments into infrastructure a better usage of the installed infrastructure is indispensable. Therefore the operation and interoperation of assistance and telematics systems become more and more necessary. Regarding these facts Highway Pilot was developed at Daimler Trucks. The Highway Pilot System moves the truck highly automated and independent from other road users within the allowed speed range and the required security distance. Daimler Trucks owns diverse permissions in Germany and the USA for testing these technologies on public roads. Next generation is the Highway Pilot Connect System that connects three highly automated driving trucks. The connection is established via Vehicle-to-Vehicle communication (V2V).
Technical Paper

Virtual Transfer Path Analysis at Daimler Trucks

2009-05-19
2009-01-2243
As for passenger cars, the overall noise and vibration comfort in commercial trucks and busses becomes an increasingly important sales argument. In order to effectively reduce the noise and vibration levels it is required to identify possible NVH issues at an early stage in the vehicle development process. For this reason a so-called “Virtual Transfer Path Analysis” (VTPA) method has been implemented which combines the results obtained from the conventional multi-body simulation and finite element method approaches. The resulting VTPA tool enables Daimler Trucks to systematically investigate and predict the complex interaction between powertrain excitation and the resulting vehicle response well before hardware prototypes become available. An overview of the theory is presented as well as the practical application and outcome of the technique applied in a past product development.
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