Car Cabin Research Articles

The impact of active components wear on psychoacoustic parameters of noise in a car cabin

The automotive industry is undergoing an electromobility revolution. Changing a car's drive unit influences the vibroacoustics of a car's interior. Drive-train noise at low car speeds and in the low-frequency range is no longer dominant. There is no masking effect due to the noise of the combustion engine, and a passenger paradoxically may perceive the noise of a car as less pleasant. Moreover, existing vibroacoustic requirements have to some extent taken into account the change in the noise of components with the usage time, but there are still areas that require further research. This paper focuses on the study of electric adjustable seats, power windows and power exterior mirrors in different wear states, to determine the significant psychoacoustics changes of the selected car component's noises. The study is part of extensive research that aims to revise the current vibroacoustic requirements for new components and to determine how they could be tested and evaluated.

How to deal with unsuspected source of annoyance in electric vehicle cabin using the "sonic augmented" concept?

The disappearance of the main source of noise with electric vehicles resulted in a breakthrough in car cabin sound experience. Despite significantly lowering the sound level pressure, one cannot claim perfect quietness is achieved. Indeed, as the auditory masking produced by the internal combustion engine is not effective anymore, unsuspected sounds such as electric whistling, whining or switching are now part of this sound environment and may be identified as unpleasant sounds. However, drivers' expectations are to have audible feedback indicative of vehicle operation that matches their expectations. Therefore, the presence of unwanted and unpleasant sounds, on the one hand, and the absence of desired and informative sounds, on the other hand, is an opportunity for sound design to create a new sound environment inside car cabins. The present work proposes a "sonic augmented" concept based on the idea of adding designed sounds, called "masks", participating both in the overall soundscape augmentation and in the attenuation of unpleasant sounds, called "defects". Sound design strategies with different parametrizations will be presented, as well as the results of two perceptive experiments whit the aims at evaluating the impact on perceptive attenuation of "defects" and the overall sound quality.

The crossover frequency of acoustic simulation for small-scale enclosures by wave and statistic based methods

In the field of room acoustic simulation, wave-based and statistical numerical methods are pivotal for acquiring sound field characteristics. Although the Schroeder Frequency has been utilized to deduce the suitable frequency range of these methods in large enclosures, the crossover frequency warrants further investigation for the small-scale enclosures with complicated inner structures, such as car cabins. This work aims to explore the applicable frequency range of these acoustic simulation methods for a small-scale model, which means identifying the crossover frequency between wave-based Finite Element Method (FEM) and statistical Ray Tracing Method (RTM). First, the crossover frequency was analyzed by the Schroder Frequency equation and modal density estimated from the room transfer functions (RTFs) in a simplified car model, which considering the interior with and without seat occlusion. Further, the crossover frequency was validated by comparing the magnitude spectra of RTFs simulated by FEM and RTM. This work provides a foundational frequency reference for applying statistical acoustic methods in small-scale enclosures.

Preliminary study of the thermoelectric cooler and heat pipe application for the cooling system in cabin pickup car

Abstract Car cooling systems are essential equipment to make passengers comfortable, but their energy consumption is very high. Thermoelectric technology has been widely applied as a cooler in many applications, but its use as a car cooler has not been widely used. This research aims to conduct a preliminary study using thermoelectric coolers (TEC) as alternative coolers in pickup cars and to investigate the effect of thermoelectric module and heat exchanger configurations on cooling systems performance. A-TEC cooling system usually uses conventional heat sinks on the cold side and hot side of the TEC. In this study, heat pipes are used as heat exchangers on the hot side of TEC to improve its performance. The cooling system consists of 2 units installed at the rear of the pickup car cabin. Tests were varied using 2 TEC modules arranged in series and 4 TECs arranged in parallel thermal and electrical series. The results showed that using two cooling system units consisting of four TEC modules equipped with heat pipes was able to cool the temperature of the pickup car cabin at 27.4 °C and obtained the highest COP value of 1.16. It shows heat pipes can enhance TEC cooling system performance, producing lower cabin temperatures than conventional heat sinks.

How Does Aesthetic Design Affect Continuance Intention in In-Vehicle Infotainment Systems? An Exploratory Study

With the digitalization of automobile cabins, in-vehicle infotainment systems play an increasingly pivotal role in vehicles. This study aims to understand how the interface aesthetics of the in-vehicle infotainment system affect users’ continuance intention in in-vehicle infotainment systems. Based on a literature review, a theoretical model was constructed, encompassing seven latent variables: simplicity, colorfulness, diversity, craftsmanship, functional value, emotional value, and continuance intention. Analysis of 243 valid questionnaires revealed that both functional and emotional values serve as crucial mediators in encouraging users to continue using the in-vehicle infotainment system, with functional quality being the core element. Moreover, simplicity, diversity, and craftsmanship indirectly affect continuance intention by influencing both functional and emotional values. These findings underscore the need for future designers of in-vehicle infotainment systems to focus on interface functionality and emotional needs, and to ensure that content is concise, engaging, user-friendly, and visually polished, thereby enhancing the user experience and fostering the intention to continue usage.

Virtual feedback control of interior road noise based on headrest loudspeakers

This paper analyzes the factors that affect the noise reduction performance of feedback control based on remote microphone technique (RMT) and how these factors can be exploited to improve the control performance. First, simulations were conducted to compare the noise reduction performance of employing feedback control directly at the virtual microphone (located at the ear position) and on the physical microphone (located on the headrest), as well as the RMT-based feedback control system. Then the impact of the delay of the virtual secondary path and the coherence between physical and virtual signals on the noise reduction performance of the RMT-based feedback control system was analyzed. It is found that the noise reduction performance can be improved by reducing the delay of the virtual secondary path or increasing the number of physical microphones. Finally, experiments of a dual-channel control system conducted inside an electric car cabin demonstrate that the feedback control strategy based on RMT achieves a binaural noise reduction of 3.4 dBA when employing 4 physical microphones to estimate sound pressure at the ear positions. This approach achieves similar performance but is more cost-effective than a feedforward system using multiple reference sensors.

An Experimental Performance Assessment of Temporal Convolutional Networks for Microphone Virtualization in a Car Cabin.

In this paper, the experimental results on microphone virtualization in realistic automotive scenarios are presented. A Temporal Convolutional Network (TCN) was designed in order to estimate the acoustic signal at the driver's ear positions based on the knowledge of monitoring microphone signals at different positions-a technique known as virtual microphone. An experimental setup was implemented on a popular B-segment car to acquire the acoustic field within the cabin while running on smooth asphalt at variable speeds. In order to test the potentiality of the TCN, microphone signals were recorded in two different scenarios, either with or without the front passenger. Our experimental results show that, when training is performed in both scenarios, the adopted TCN is able to robustly adapt to different conditions and guarantee a good average performance. Furthermore, an investigation on the parameters of the Neural Network (NN) that guarantee the sufficient accuracy of the estimation of the virtual microphone signals while maintaining a low computational complexity is presented.

Active vibration control of gearbox housing using inertial mass actuators

Reducing carbon emissions is a primary goal in the global effort to combat climate change. Decreasing the weight of a vehicle improves efficiency and significantly reduces emissions. One of the main contributors to the vehicle’s weight is the gearbox. However, this approach presents a challenge as lightweight transmission systems experience higher vibrations and noise emission levels. In this paper, an economical active vibration control system is developed to control the vibration levels of an automotive gearbox housing. The gearbox’s mounting points are targeted to reduce the transmitted vibrations to the car cabin. The active control system aims to target high-frequency vibrations between 1000 Hz and 5000 Hz. A compact piezoelectric inertial mass actuator is designed and tested on a gearbox-constructed setup that simulates the vibrations and noise similar to a commercial automotive transmission system. The developed test-rig is excited by a piezo stack actuator at the input shaft. Filtered-x least mean square algorithm is implemented on a high-speed microcontroller, and the vibration levels are significantly reduced using the active system. An average reduction of approximately 8.5 dB is achieved between 1000 Hz and 1500 Hz, an average reduction of approximately 14 dB is obtained between 1500 and 2000 Hz, and an average reduction of 10.8 dB is attained between 2500 and 5000 Hz.

Numerical Simulation of Exhaled Particle Transmission in a Car Cabin with Open Windows

Numerical Simulation of Exhaled Particle Transmission in a Car Cabin with Open Windows

Holistic assessment of advanced technology for ultrafine particle filtration in car cabins

Requirements on cabin air quality are constantly increasing. The objective is to protect the passengers from ultrafine particles and harmful gases, particularly in small volumes such as car cabins, where pollution is more concentrated in absence of any filtration strategy. It is necessary to extend the single filter approach and combine it with advanced filtration technologies (high separation efficiency), and thus create an effective multistage filtration system. The investigation work is built around a holistic approach. A complete 1D-simulation model has been calibrated with experimental results from a dedicated test rig and an electric vehicle. The results showed a significant improvement of particle level in the cabin with the advanced filtration system. Additionally, an appropriate ventilation strategy has been implemented to deal with the air entering the cabin by other means than the blower operation. This “infiltration”, triggered by vehicle speed, allows pollution to enter the cabin without any filtration stage.

Evaluation of airborne transmission of respiratory contaminants in a passenger car cabin with window opening

Exhaled aerosols can be suspended in the air for long periods, facilitating the transmission of highly infectious respiratory diseases. The risk of exposure to occupants varies due to different usage conditions and driving scenarios of moving vehicles. Therefore, the present study investigates the airborne transmission of contaminants generated by coughing in a moving vehicle and explores the relationship between aerosol dispersion and fluid exchange between the interior and exterior domains of the car under the influence of window opening configurations, seating layouts and driving speeds. The results show that the cross-opening configurations provide a superior contaminant removal efficiency. The effect of seating layout on removal efficiency is significant, although it has a slight effect on air change rate (ACH). The best removal efficiency can be obtained when the passenger sits in the front seat with the right front window opening. Furthermore, the in-cabin ACH is almost linearly correlated with the driving speed. Higher speeds reduce contaminant concentrations faster. However, the risk of driver exposure does not depend solely on ACH, the peak cumulative contaminant concentration and residence time also need to be considered. This study offers data for the prevention and control of respiratory infectious diseases.

Case study of automotive NVH topics induced by HVAC systems integration

Within the automotive market, HVAC systems are of critical importance in ensuring passengers' thermal comfort inside the car cabin as well as complying with regulatory defogging functions. These systems involve various components such as blowers, thermal exchangers, actuators... over a wide range of well-known technologies and also innovations on newly introduced designs and products. Currently, within the established electrification trend worldwide, HVAC systems became one of the most important embedded systems, possibly inducing major contributions of noise and vibration. These NVH topics can emerge through various transfer paths inside the car cabin causing significant discomfort to passengers. During development and production stages, the NVH behavior at component level is mastered by both suppliers and OEMS according to internal standards and specifications. However, implementation into the complete vehicle can induce a specific NVH behavior unrelated to the compliance status at component level. Integration impact cases are highly reinforced within electrification trends as they involve more and more design changes with less technical background. Through a practical case study, this paper focuses on the NVH behavior induced by the integration of HVAC systems in the US market. Transfer paths analysis and solutions are investigated to improve the NVH behavior and set the product intrinsic limits giving the targeted vehicle.

Large-Scale Measurements Using Robotic Volumetric LPT With Shake-The-Box Inside A Vehicle Cabin: Influence Of Different Fan Speeds On The Flow Topology

In this work, the flow topology inside a passenger car cabin for different fan speeds of the heat, ventilation and air conditioning (HVAC) system is investigated using robotic volumetric Lagrangian Particle Tracking (LPT). The coaxial volumetric velocimeter (CVV), also called MiniShaker, in combination with a robotic arm enables the measurement of the complete passenger's side. In total 37 CVV perspectives (sub-volumes) were measured. At each position 3000 double frame images were recorded. The interior was painted black and the mannequin was wrapped with black aluminum foil in order to keep reflections at a low level. Experimental results for three different fan speeds using helium-filled soap bubbles (HFSB) as tracers and Shake-the-Box (StB) algorithm for the three-dimensional LPT data analyses show that the flow topology changes significantly with increasing fan speeds. At higher fan speeds the flow fields show the highest complexity with four vortices.

Concentrations of potentially endocrine disrupting chemicals in car cabin air and dust – Effect of temperature and ventilation

Materials in car cabins contain performance-enhancing semi-volatile organic compounds (SVOCs). As these SVOCs are not chemically bound to the materials, they can emit from the materials at slow rates to the surrounding, causing human exposure. This study aimed at increasing the understanding on abundance of SVOCs in car cabins by studying 18 potential endocrine disrupting chemicals in car cabin air (gas phase and airborne particles) and dust. We also studied how levels of these chemicals varied by temperature inside the car cabin along with ventilation settings, relevant to human exposure. A positive correlation was observed between temperature and SVOC concentration in both the gas and the particle phase, where average gas phase levels at 80 °C were a factor of 18–16,000 higher than average levels at 25 °C, while average particle phase levels were a factor of 4.6–40,000 higher for the studied substances. This study also showed that levels were below the limit of detection for several SVOCs during realistic driving conditions, i.e., with the ventilation activated. To limit human exposure to SVOCs in car cabins, it is recommended to ventilate a warm car before entering and have the ventilation on during driving, as both temperature and ventilation have a significant impact on SVOC levels.

Fibre Blend and Web Arrangement for Optimized Dust-Holding, Hydrophobic, and Thermal Properties of Needle-Punched Nonwovens

PM2.5 filters with hydrophobicity and thermal resistance are preferable for automobile cabins, engine air intake, and indoor applications, safeguarding against moisture ingress, microbial growth, and temperature fluctuations, and ensuring optimal air quality. This study explored the effects of blending five fibres with different web arrangements and fibre blend compositions on needle-punched dust-holding, hydrophobic, and thermal properties. Polyphenylene sulfide (PPS), polypropylene (PP), polyester (PET), polylactic acid (PLA), and polyacrylonitrile (PAN) were blended in different proportions to produce the samples. The method included opening, blending, carding, web laying, and needle punching to produce eight samples with cross-laid, parallel-laid, and pre-needled parallel-laid web configurations. Standard test methods were employed for the characterization. The results showed a dust holding capacity of > 3,423,000 particles/cm2, the highest WCA of 133.12°, and the highest thermal resistance of 0.24255 m2KW−1. Based on the ANOVA analysis, web arrangement and pre-needling did not have a significant impact on the hydrophobicity of the samples. N0, N1, and N2 showed similar high water contact angles (~ 126°), indicating that the hydrophobicity was more affected by the chemistry of the fibre blend than by the web structure. Turkey’s analysis of other samples strengthened this idea. However, they had a substantial impact on the porosity, air permeability, dust-holding capacity, and thermal properties at a P-value ≤ 0.05. The findings provide insightful information regarding the complex interactions among fibre content, web layout, and pre-needling to develop sophisticated needle-punched PM2.5 filters.

96‐3: Invited Paper: Next‐Gen Interactions: Creative Sensing Solutions for Automotive Capacitive Knobs on Displays

Automakers are adding back mechanical knobs to modern car cabins to address concerns about the difficulty of adjusting vehicle setting controls through the touchscreen interface. Passive capacitive knobs attached to touchscreens are a great solution as they provide a seamless interface while using the same capacitive sensors that sense finger touches. Existing knobs rely on capacitive coupling to a user's hand, making it difficult to support gloved hands. The proposed knob resolves this by employing a unique sensing architecture while providing additional features such as initial state detection and fall‐off detection.

Evaluation of the airflow distribution of a vertical air ventilation system in a car cabin using PIV measurements and CFD simulations

The main goal of a ventilation system in the car cabin in general is to guarantee an adequate thermal comfort for all passengers and to enable a good air quality with sufficient air supply into the cabin. Quantifying the indoor air distribution is essential to provide the necessary thermal comfort and the required air quality. The aim of this study is therefore to analyze the subsequent airflow distribution of the vertical air ventilation system presented as a possible solution for future cars with modern interior designs. With the vertical air ventilation concept, air vents are located at the ceiling and floor area of the car cabin, as ceiling and floor regions enable a large-area influx of air into the car cabin and allow accessibility to passengers in every seating position. For the analysis of the airflow distribution of the ventilation system, Particle Image Velocimetry (PIV) measurements have been performed with a test vehicle in a climate chamber under specific conditions. Two different thermal manikins, one heated and the other unheated, have been used in the experiments. The results of the comparison between the two thermal manikins reflect a relatively low to medium impact of the human thermal natural convection on the airflow pattern around the manikin in the different air distribution modes of the vertical air ventilation system. Using the same ventilation settings, numerical simulations have been performed. The results of the numerical simulations are analyzed and compared with the results of the PIV measurements. The developed numerical model shows a good agreement with the experiments. It can hence be used for example in further studies to evaluate the thermal comfort or the air quality of the vertical airflow system as a new ventilation concept for future car interior designs.

A battery-free, wireless, flexible bandlike e-nose based on MEMS gas sensors for precisely volatile organic compounds detection

Real-time detection of VOCs in the car cabin is crucial for protecting driver’s health. MOS gas sensors, with the advantages of low cost, simplicity and fast response, are widely used for gas monitoring. However, they typically exhibit broad-spectrum responsiveness to multiple gases. Despite numerous improvement strategies proposed from the perspective of MOS material modification, achieving ideal gas selectivity remains challenging. An e-nose based on gas sensor array is a promising approach for gas identification. However, the hardware circuit system and battery supply module in traditional e-nose result in large size, complex structure, and inconvenience in use. In this work, we synthesized MOS materials with different morphologies to form a microarray containing six MEMS gas sensors, and developed a novel belt-shaped wireless and battery-free flexible e-nose, where a mobile phone serves as its wireless power supply and data communication system. This design provides a flexible e-nose with excellent wearability and safety, allowing users to monitor surrounding gas conditions at any time conveniently. Subsequently, we design pattern recognition models using algorithms such as MLP, RF, XGBoost, and LGBM, in combination with ensemble learning strategies, achieving high accuracy in VOCs classification and low-error concentration prediction. This flexible e-nose holds significant application value for gas detection in car cabins and indoor environments.

A Comparative Study on the Operational Efficiency of Joystick and Touch Screen Control Methods for Sugarcane Harvesters

Reducing cumbersome mechanical control components is one of the trends of modern agricultural machinery towards a high degree of automation. Whether the control components of sugarcane harvesters can gradually be replaced by central control screens, similar to car cabins, is an unresolved question. At the level of human machine interaction, this involves comparing the efficiency between joystick and touch screen control. This paper conducts a simulated experiment to compare and study the efficiency and user experience of joystick and touch screen control in adjusting the topper and base cutter heights of sugarcane harvesters, aiming to provide a reasonable basis for the design of control interfaces in sugarcane harvester cabins. The electromyographic signals, experiment duration, and subjective cognitive evaluations of participants in both the topper and base cutter groups were analyzed. The results showed that the efficiency, learnability, and ease of use of different control methods varied under different operational tasks. For the topper that corresponds to the operating behavior and height transformation in real time, joystick control demonstrated superior ease of use and operational efficiency compared to touch screen control, with weaker learnability. There was no discernible difference in muscle activation levels between the two control methods. Consequently, joystick control is deemed more suitable for the height adjustment of the topper. Regarding the base cutter with non-real-time mapping of operating behavior and height changes, no significant disparity in ease of use and learnability was observed between the two control methods. Touch screen control yielded lower muscle activation levels and garners higher overall subjective cognitive scale ratings. Thus, touch screen control is considered more suitable for base cutter height adjustment. Lastly, the paper proposes the optimal combination of software and hardware for control components in sugarcane harvester cabins, and provides an objective and multidimensional experimental analysis method for future research on similar human machine interaction interfaces.

Systematic Review: How to reduce the car cabin temperature using solar energy?

The two biggest issues we have are the energy crisis and global warming. Both issues are made worse by the use of traditional air conditioners. Therefore, numerous techniques were devised to overcome that, including solar ventilation, solar cooling, and solar thermoelectric modules. The most suitable choice was solar thermoelectric cooling because it was safe for the environment, provided a significant drop in car cabin temperatures, and avoided using hazardous refrigeration fluids.