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The purpose of night vision systems is to provide drivers during night and adverse weather with visual information beyond the range of their headlamps and beyond the glare of an oncoming vehicle's headlamp. Thus the driver has more time to react in case of unexpected and dangerous situations. Basically, two different concepts can be followed up. Passive night vision systems visualize the thermal radiation emitted by the objects themselves [1] while active night vision systems image near-infrared radiation which is reflected by the objects in the scene. Unlike passive systems, active night vision systems need powerful near-infrared light sources and cameras which are considered especially with respect to automotive requirements. Halogen light sources are the most promising candidates because about 25 percent of the total radiated power of a 60 W lamp lies in the near-infrared wavelength range from 800nm to 1100nm.

Ensuring the robustness of vehicle systems and features is a key aspect of customer satisfaction and therefore is of vital importance to Original Equipment Manufacturers (OEMs). Both initial quality and quality over the life of the vehicle are important aspects to customers. Therefore, some features and systems require an active approach at monitoring system health. The intent of Active Noise Cancellation (ANC) systems in vehicles is to increase the customer’s perception of vehicle refinement and brand quality. Due to the nature of ANC system operation, it is critical that the system does not go divergent resulting in unwanted noise being heard by the customer. So, a method to monitor the ANC system operation and performance is required to ensure robustness. Despite tuning ANC systems considering expected vehicle build tolerances, vehicle aging and customer specific use cases, an ANC system can occasionally still go divergent in the field.

With the advent of PHEV vehicles OEMs face additional NVH issues. A particularly new issue is a low frequency booming noise caused during charging of batteries using the internal combustion engine. During charging the engine is operated at low rotational speeds and high loads, leading to pronounced low frequency noise. While in the past reducing low frequency noise either required large absorbers and/or heavy dampers, today the issue can be tackled by use of an Active Noise Cancellation system. Jaguar Land Rover decided to introduce an Active Noise Cancellation system in the PHEV variants of some of their vehicles. The system builds upon software by Müller-BBM Active Sound Technology GmbH and makes use of the existing audio amplifiers. The only extra hardware component required are microphones in the vehicle headliner.

Under city driving conditions, the powertrain represents one of the major vehicle exterior noise sources. Especially at idle and during full load acceleration, the oil pan contributes significantly to the overall powertrain sound emission. The engine oilpan can be a significant contributor to the powertrain radiated sound levels. Passive optimization measures, such as structural optimization and acoustic shielding, can be limited by e.g. light-weight design, package and thermal constraints. Therefore, the potential of the Active Structure Acoustic Control (ASAC) method for noise reduction was investigated within the EU-sponsored project InMAR. The method has proven to have significant noise reduction potential with respect to oil pan vibration induced noise. The paper reports on activities within the InMAR project with regard to a passenger car oil pan application of an ASAC system based on piezo-ceramic foil technology.

In the future, the requirements of acoustic behavior in air intake systems will continue to increase. Common passive or adaptive acoustic measures will not be able to reach higher standards while maintaining reasonable costs and packaging specifications. For new engines complying with future legislative limits in noise emissions, it will be necessary to develop active systems. This investigation analyzes the possibility of integrating an active noise cancellation system within the air intake system. An air intake system was optimized by one dimensional calculation. The components of the active system were defined according to the computational results. The acoustical feasibility of an active system were then measured and analyzed on an anechoic engine dynamometer.

This paper describes the applicability of the active noise control concept with the objective of evaluating its potentialities in automotive applications. A control system, using adaptative algorithms is proposed to attenuate the generated noise of one sound source. At the end, the simulation results of the system performance in the control of the noise generated by a truck diesel engine will be presented.

In contrast to functionality and reliability, which are more and more assumed to be a natural and necessary condition of any vehicle, the performance of Noise, Vibration and Harshness (NVH) now belongs to those features which play an essential role for the customer's purchasing decision. Sound design and vehicle interior noise control are essential parts of NVH. One tool of the NVH solution toolbox is Active Noise Control (ANC). ANC technology aims to cancel unwanted noise by generating an “anti-noise” with equal amplitude and opposite phase. Owing to the fact that human hearing has selective sensitivity for different critical bands, a new control strategy of ANC, which selectively controls the noise of specific bandwidths according to the result of specific loudness and retains the part of noise created by the normal running of facilities, trying to attenuate the unwanted and unacceptable noise, has been proposed in this paper.

According to the importance of Active Noise Control (ANC) in 3D spaces such as vehicle cabins for reducing unwanted noises inside cabins, the purpose of this paper is to demonstrate the finite element (FE) modeling, simulation and analysis of an ANC in a 3D acoustic passenger car cabin with filtered-X LMS adaptive feed forward controller. For this purpose, after creating an acoustic FE model of the passenger car cabin and calculating its resonance frequencies and mode shapes; several transfer functions of primary, secondary and feedback paths of the acoustic field is estimated in digital domain in accordance with frequency responses obtained from FE model in order to simulate the behavior of ANC system. In all simulations, acoustic feedback effect is considered and the acoustic feedback neutralization technique is used to reduce or overcome the instability potential of this effect.

New powertrain technologies like cylinder deactivation, downsizing, hybrids and even electrical vehicles present new challenges for vehicle noise control and sound design. One tool within the NVH solution toolbox is Active Noise Control (ANC) and Active Sound Design (ASD). Being in production for half a decade to enhance the new powertrain NVH experience, the technology has proven its applicability in practice. Further production applications of the technology are anticipated for the next years. The paper presents an overview of the current status and global application of ANC and ASD technologies. It gives a short outlook to new technologies and applications from road noise cancellation to electrical vehicle exterior sound design. It concludes with a discussion of the challenges arising when bringing ANC into real production - many of them connected with the very interdisciplinary approach required to get the technology applied.

Passengers sitting on the back seats of cars while talking on their mobiles can easily experience the invasion of their speech privacy by the driver. Protecting speech privacy can be done by utilizing masking sounds - masking sound may be so loud that it annoys both drivers and speakers. In this research, the feasibility of utilizing active noise control (ANC) which aims to reduce the level of speech at the driver’s seat and, hence, is able to lower the needed level of masking sounds while still protecting the speech privacy is investigated. Speech reception threshold (SRT), which is a subjective measurement method for speech intelligibility, is proceeded for seeing the effect of ANC on speech intelligibility when the masking sound is in use. The SRT measurement result implied that utilizing ANC to reduce the speech level of the back-seat passenger at the driver’s seat is able to lower the needed level of masking sound for keeping the speech privacy.

Interior noise in motor vehicles is essentially influenced by the engine which may contribute via both, structural and acoustic transmission paths. This engine related interior noise components may be controlled deliberately by active control measures without changing any source or transfer paths characteristics. Besides attenuating dominant noise components, the approach may equally be used to optimise interior sounds with respect to sound quality. Based on general considerations how active noise and vibration control measures may effect subjective criteria, the paper gives examples how different, sometimes extremely contrasting noise characteristics may be realised in a given car.

To significantly increase fuel efficiency while keeping power and performance of its signature S models, AUDI developed a new 4.0 TFSI engine with Cylinder on Demand technology and introduced it with its new S6, S7 and S8 models. To manage upcoming NVH issues due to this new technology and keep the intended sporty V8 note of the engine under all operating conditions, a broad range of new and advanced technologies was introduced with these vehicles. This paper focusses on the Active Noise Control system and its development. It describes the ANC system from a control theory perspective in addition to the acoustical perspective. Special features of the system include the availability of multiple tunings (4/8 cylinder mode) to support the specific overall sound character and the fast switching process as switching between different cylinder configurations might be as fast as 300 ms. In addition, the system also includes specific features that allow an advanced audio system diagnosis.

Active Noise Control (ANC) systems for passenger cars exhaust systems have been announced since many years but have not found their way onto market until now. This paper gives an overview about the remaining weak points of such a system and proposes solutions suited for improved heat insulation, loudspeaker capabilities and Sound Design possibilities. Results achieved with a V6 engine vehicle are then related and discussed.

On the study of reducing the disturbance on driver’s attention induced by low frequency vehicle interior stationary noise, a subjective evaluation is firstly carried out by means of rank rating method which introduces Distraction Level (DL) as evaluation index. A visual-finger response test is developed to help evaluating members better recognize the Distraction Level during the evaluation. A non-linear back propagation artificial neural network (BPANN) is then modeled for the prediction of subjective Distraction Level, in which linear sound pressure RMS amplitudes of five Critical Band Rates (CBRs) from 20 to 500Hz are selected as inputs of the model. These inputs comprise an input vector of BPANN. Furthermore, active noise equalization (ANE) on DL is realized based on Filtered-x Least Mean Square (FxLMS) algorithm that controls the gain coefficients of inputs of trained BPANN.

The effective identification and control of powertrain structure borne harmonic noise is a key to achieve a desired noise quality profile in a vehicle. Much work is being done in this field to refine and develop sound engineering techniques suitable for application at each stage of a vehicle development programme. For prototype development and trouble shooting, transfer path analysis and source identification techniques are in use today with varying degrees of success and application complexity. Investigation tools which are fast, do not require extensive vehicle dismantling and yet provide reliable answers, will be of value to the NVH and sound quality engineer. A new Active Path Tracking method is described which is relatively quick and offers practical confirmation of the influence of identified paths. The method involves the novel adaptation of Active Noise Cancellation techniques to the task of source identification.

The effective identification and control of powertrain structure borne harmonic noise is one key for achieving the desired noise pattern in a vehicle. Much work is being done in this field to refine and develop transfer path analysis techniques suitable for application at each stage of a vehicle development program. For vehicle application, transfer path analysis and source identification techniques are in use today with varying degrees of success and application complexity. Investigation tools which are fast, do not require extensive vehicle dismantling and yet provide reliable answers, are of great value to NVH and sound quality engineers. A novel Active Path Tracking (APT) method has been developed which is fast to apply and offers immediate practical confirmation of the contributions of all identified chassis transmission paths to the vehicle interior.

Pedestrian protection is an upcoming field for research and development. Active pedestrian protection is described from a system perspective. In this view, the development of an active pedestrian protection system is shown. First an overview on statistics and legal requirements is given and the system requirements are discussed. Sensor concepts and realizations are shown, also different test methods and results are explained. FE-simulations to complete and later replace additional tests are developed, after cross check with the experimental results. In combination with the shown actuator concept this leads to a full functioning active pedestrian protection system.

Combustion diagnostics of highly diluted mixtures are essential for the estimation of the combustion quality, and control of combustion timing in advanced combustion systems. In this paper, a novel fast response flame detection technique based on active plasma is introduced and investigated. Different from the conventional ion current sensing used in internal combustion engines, a separate electrode gap is used in the detecting probing. Further, the detecting voltage across the electrode gap is modulated actively using a multi-coil system to be slightly below the breakdown threshold before flame arrival. Once the flame front arrives at the probe, the ions on the flame front tend to decrease the breakdown voltage threshold and trigger a breakdown event. Simultaneous electrical and optical measurements are employed to investigate the flame detecting efficacy via active plasma probing under both quiescent and flow conditions.

Heavy duty hydrogen (H2) internal combustion engines (ICEs), typically conversions from base diesel engines, can experience significant deterioration of combustion efficiency with enleanment despite relative engine stability due in part to non-optimized combustion chamber geometry for spark ignited (SI) combustion. This causes un-combusted H2 to “slip” into the exhaust largely undetected since it is not a typically measured exhaust species. In this study, several implications of H2 slip in H2 ICEs are explored. The sensitivity of air fuel ratio (AFR) measurement to H2 slip is discussed. The challenge this poses for closed-loop transient controls and the impact on nitrogen oxides (NOx) emissions are also shown. Finally, test results from an H2 ICE using an active pre-chamber highlight the improvement in combustion efficiency and transient stability relative to a baseline SI engine.

The radiation environment in and around the International Space Station will be studied by NASA using a set of three active radiation measurement instruments. Discussion and preliminary results of the data collected from Expeditions 1 and 2 will be presented in terms of the radiation field at low earth orbit and shielding considerations.