Search

Deploying an airbag when a vehicle occupant is too close to it can cause injury. An adaptive Airbag Control Unit (ACU) would improve the effectiveness of the safety system, provided it is aware of the actual position of the occupants once the crash is going to occur. Occupants can be monitored with vision-based and radar-based sensing in the vehicle, but the research question is whether other reliable devices exist. In this research, a real seat is equipped with four sensors in the supports from the floor, as well as an Inertial Measurement Unit (IMU) and a microcontroller. The device is capable of identifying correct position or different Out of Position (OP) conditions and inform an adaptive ACU. The paper presents the seat layout in detail and its testing in extensive driving experiments with multiple participants. Depending on the position of the driver, the identification is correct 45–100% of the time. Monitoring the occupant position by a sensorized seat is feasible and can improve the reliability of the onboard safety system when integrated with other occupant monitoring devices. [ABSTRACT FROM AUTHOR]

Deploying an airbag when a vehicle occupant is too close to it can cause injury. An adaptive Airbag Control Unit (ACU) would improve the effectiveness of the safety system, provided it is aware of the actual position of the occupants once the crash is going to occur. Occupants can be monitored with vision-based and radar-based sensing in the vehicle, but the research question is whether other reliable devices exist. In this research, a real seat is equipped with four sensors in the supports from the floor, as well as an Inertial Measurement Unit (IMU) and a microcontroller. The device is capable of identifying correct position or different Out of Position (OP) conditions and inform an adaptive ACU. The paper presents the seat layout in detail and its testing in extensive driving experiments with multiple participants. Depending on the position of the driver, the identification is correct 45–100% of the time. Monitoring the occupant position by a sensorized seat is feasible and can improve the reliability of the onboard safety system when integrated with other occupant monitoring devices.

Featured Application: Vibration Isolation System for Vehicle's Seats. Improving the vibration isolation for the seat of small vehicles under low excitation frequencies is important for providing good comfort for the driver and passengers. Thus, in this study, a compact, low-dynamic, and high-static stiffness vibration isolation system has been designed. A theoretical analysis of the proposed quasi-zero stiffness (QZS) isolator system for vehicle seats is presented. The isolator consists of two oblique springs and a vertical spring to support the load and to achieve quasi-zero stiffness at the equilibrium position. To support any additional load above the supported weight, a sleeve air spring is used. Furthermore, the two oblique springs are equipped with a horizontal adjustment mechanism that is aimed to reach higher frequencies with the existed stroke when a heavy load is applied. The proposed system can be fitted for small vehicles, especially for B-segment and C-segment cars. Finally, the simulation results reveal that the proposed system has a large isolation frequency range compared to that of the linear isolator. [ABSTRACT FROM AUTHOR]

This research introduces an air spring vibration isolator system (ASVIS) based on a negative-stiffness structure (NSS) to improve the vehicle seat's vibration isolation performance at low excitation frequencies. The main feature of the ASVIS consists of two symmetric bellows-type air springs which were designed on the basis of a negative stiffness mechanism. In addition, a crisscross structure with two straight bars was also used as the supporting legs to provide the nonlinear characteristics with NSS. Moreover, instead of using a vertical mechanical spring, a sleeve-type air spring was employed to provide positive stiffness. As a result, as the weight of the driver varies, the dynamic stiffness of the ASVIS can be easily adjusted and controlled. Next, the effects of the dimension parameters on the nonlinear force and nonlinear stiffness of ASVIS were analyzed. A design process for the ASVIS is provided based on the analytical results in order to achieve high static–low dynamic stiffness. Finally, numerical simulations were performed to evaluate the effectiveness of the ASVIS. The results obtained in this paper show that the values of the seat displacement of the ASVIS with NSS were reduced by 77.16% in comparison with those obtained with the traditional air spring isolator without NSS, which indicates that the design of the ASVIS isolator with NSS allows the effective isolation of vibrations in the low-frequency region. [ABSTRACT FROM AUTHOR]

Ana sanayi firmaları üretimini talep ettikleri taşıt koltuklarının belirli şartnamelere uygun olmasını isterler. İmalatçı firma bu durumda koltuğun prototipini üretip birtakım değiştirme ve iyileştirmelerle teknik şartları sağlamaya çalışabilir. Fakat bu yol pahalı ve zaman alıcıdır. Bu durumda alternatif yöntem koltuğun sonlu eleman modelini geliştirmek ve üzerinde parametrik çalıştırmalar gerçekleştirmektir. Bu çalışmada öncelikle bir ticari araç koltuğunun iskelet aksamına eklenen sünger, kılıf, sırt tahtası gibi katmanların koltuğun ileri-geri ve yanal doğrultudaki modal parametrelere etkisi deneysel olarak incelenmiştir. Buradan elde edilen sonuçlara göre koltuk iskeleti sonlu eleman modeline katmanlar çeşitli kütle ve katılık parametreleriyle eklenmiştir. Daha sonra sonlu eleman modelinin gerçek koltuk modeliyle uyumlu olması için bu parametrelerin uygun değerleri cevap yüzeyi yaklaşımı ile belirlenmiştir. Ayrıca bu yöntemle, ilgili katmanların hangilerinin daha etkili olduğu da görülmüştür. Sonuç olarak, sonlu eleman modeli ile elde edilen temel frekansların her iki doğrultu için deneysel frekanslarla uyumlu olduğu, özellikle ileri-geri harekette frekans cevabı fonksiyonu genliklerinin de birbirine oldukça yakın olduğu görülmüştür.

In order to detect the type of vehicle seat and the missing part of the spring hook, this paper proposes an improved RANSAC-SURF method. First, the image is filtered by a Gauss filter. Second, an improved RANSAC-SURF algorithm is used to detect the types of vehicle seats. Extract the feature points of vehicle seats. The feature points are matched according to the improved RANSAC-SURF algorithm. Third, the image distortion of the vehicle seat is corrected by the method of perspective transformation. Determine whether the seat's spring hook is missing or not according to the absolute value of the gray difference between the image collected by the camera and the image of the normal installation. The experimental results show that the MSE of the Gauss filter under a 5 * 5 template is 19.0753, and the PSNR is 35.3261, which is better than that of the mean filter and the median filter. The total matching logarithm of feature points and the number of intersection points are 188 and 18, respectively, in the improved RANSAC-SURF matching algorithm. [ABSTRACT FROM AUTHOR]

Improving the vibration isolation for the seat of small vehicles under low excitation frequencies is important for providing good comfort for the driver and passengers. Thus, in this study, a compact, low-dynamic, and high-static stiffness vibration isolation system has been designed. A theoretical analysis of the proposed quasi-zero stiffness (QZS) isolator system for vehicle seats is presented. The isolator consists of two oblique springs and a vertical spring to support the load and to achieve quasi-zero stiffness at the equilibrium position. To support any additional load above the supported weight, a sleeve air spring is used. Furthermore, the two oblique springs are equipped with a horizontal adjustment mechanism that is aimed to reach higher frequencies with the existed stroke when a heavy load is applied. The proposed system can be fitted for small vehicles, especially for B-segment and C-segment cars. Finally, the simulation results reveal that the proposed system has a large isolation frequency range compared to that of the linear isolator.

Compared to the mesh-based finite element modeling, the lumped-network modeling is more useful for the multi-physical system and the simulation of many design variants. A non-uniform discretization of the seat surface into planar multi-patches is introduced for reproducing beneficial features of FEM by a lumped-network approach. These multi-patches are individually attached to the seat frame by visco-elastic polyurethane (PU) foam elements, which can handle the strain rate effect and the hysteresis. This approach is a mimicking the FEM concept while keeping the computational robustness of the Modelica solution. [ABSTRACT FROM AUTHOR]

This research introduces an air spring vibration isolator system (ASVIS) based on a negative-stiffness structure (NSS) to improve the vehicle seat’s vibration isolation performance at low excitation frequencies. The main feature of the ASVIS consists of two symmetric bellows-type air springs which were designed on the basis of a negative stiffness mechanism. In addition, a crisscross structure with two straight bars was also used as the supporting legs to provide the nonlinear characteristics with NSS. Moreover, instead of using a vertical mechanical spring, a sleeve-type air spring was employed to provide positive stiffness. As a result, as the weight of the driver varies, the dynamic stiffness of the ASVIS can be easily adjusted and controlled. Next, the effects of the dimension parameters on the nonlinear force and nonlinear stiffness of ASVIS were analyzed. A design process for the ASVIS is provided based on the analytical results in order to achieve high static–low dynamic stiffness. Finally, numerical simulations were performed to evaluate the effectiveness of the ASVIS. The results obtained in this paper show that the values of the seat displacement of the ASVIS with NSS were reduced by 77.16% in comparison with those obtained with the traditional air spring isolator without NSS, which indicates that the design of the ASVIS isolator with NSS allows the effective isolation of vibrations in the low-frequency region.

A vehicle seat represents an automotive passive system because it limits the damage caused to passengers in the events of an accident or a crash. This way, the present work intends to evaluate the safety of an anchorage mechanism of a frontal vehicle driver seat considering two hazardous situations rear and frontal impacts. Performing a nonlinear FE in static and transient analyses provide the stress distribution in the main components of the mechanism, such as the inner track, the lock device and the bolts using Ansys®. Regulation N° 17 from Un/ECE regulates the acceleration levels predicted in a crash test and therefore applied in the simulation. In addition, departing from a crash of 5g a fatigue analysis is carried out. From this particular analysis, it becomes possible to evaluate the actual safety of the vehicle seat after a minor crash. [ABSTRACT FROM AUTHOR]

The vehicle seat modal characteristics (in particular, the first resonant frequency and the corresponding modal shape) play important roles in the seat design and the ride comfort. This paper investigated the relationship between the first modal characteristics and the positions of the adjusters on the vehicle seat. There are four adjusters on the vehicle seat to change its position so as to match the driver's somatotype, the driving and the sitting habits. Different seat positions inevitably cause changes in the resonant frequency. An orthogonal array method was adopted to evaluate the influence levels of the adjusters by using a Pareto chart. It was found that the first modal (fore-and-aft) shape is almost uninfluenced by the variations in the adjuster positions, whereas the first modal frequency is greatly influenced by the changes in the adjuster positions. The first modal frequency is most affected by the variation in the slider position, followed by the variation in the headrest adjuster position, the variation in the recliner position and the variation in the height adjuster position. [ABSTRACT FROM AUTHOR]

Characterising the coupling between the occupant and vehicle seat is necessary to understand the transmission of vehicle seat vibration to the human body. In this study, the vibration characteristics of the human body coupled with a vehicle seat were identified in frequencies up to 100 Hz. Transmissibilities of three volunteers seated on two different vehicle seats were measured under multi-axial random vibration excitation. The results revealed that the human-seat system vibration was dominated by the human body and foam below 10 Hz. Major coupling between the human body and the vehicle seat-structure was observed in the frequency range of 10–60 Hz. There was local coupling of the system dominated by local resonances of seat frame and seat surface above 60 Hz. Moreover, the transmissibility measured on the seat surface between the human and seat foam is suggested to be a good method of capturing human-seat system resonances rather than that measured on the human body in high frequencies above 10 Hz.Practitioner Summary:The coupling characteristics of the combined human body and vehicle seat system has not yet been fully understood in frequencies of 0.5–100 Hz. This study shows the human-seat system has distinctive dynamic coupling characteristics in three different frequency regions: below 10 Hz, 10–60 Hz, and above 60 Hz. [ABSTRACT FROM PUBLISHER]

This paper describes a new cushion using a urethan within an air cell (UA cell). In order to reduce vibrations of occupants, we propose the UA cell enable to control mechanical properties by an air pressure in the vehicle seat. It is necessary to clear mechanical properties of UA cell for the reduction of vibration. The purpose of this paper is to clarify the mechanical properties of the UA cell when the air pressure of the UA cell changes. In this study, the UA cell consisted of a liner polyethylene and the urethan is designed. Relationships between the air pressure and the mechanical properties of UA cell are examined by a measurement using a vibration exciter. From these results, frequency response functions are changed by controlling the air pressure. A spring constant and a viscous damping coefficient are estimated from the frequency response functions. Relationships between the air pressure and mechanical properties are approximated by a 7th‐degree function. In addition, the variation range of the UA cell is wider than that of the air cell in the mechanical properties when the thickness of the UA cell and the air cell are changed within the same range. Therefore, it was shown that the UA cell could be used as an actuator to control the mechanical properties.

Copyright of Technical Transactions / Czasopismo Techniczne is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Passive posture variation in vehicles could enable variation in pressure distribution and muscle activity to counter physical fatigue from static seating resulting in more comfort. The difference in posture, however, should not lead to perceived discomfort and aspects of driving should be considered such as operating the steering wheel, pedals and vision in the mirrors. OBJECTIVE: This study sets out to find out how much postural variation occurs during the driving task and how sensitive is the human body to these changes. METHODS: The first experiment was user evaluation and assessed how and when the changes in seat configuration were noticeable to the human body. The second experiment evaluated the influence of varying inclination of the backrest and the seat pan by the rating of typical aspects of driving. RESULTS: The differences in seat configuration during experiment 1, were so small that there was no consistency in the ratings for the same configuration. The most critical feature that restrains the posture is the location of the rear view mirror. CONCLUSIONS: The range-of-motion is defined as -1° to +1° for the seat pan and 0° to +1.5° for the backrest based on the results of experiment 2 because of the restraints of the driving task. [ABSTRACT FROM AUTHOR]

The ISO 2631-1 (1997) provides methodologies for assessment of the seated human body comfort in response to vibrations. The standard covers various conditions such as frequency content, direction and location of the transmission of the vibration to the human body. However, the effects of seat structural dynamics mode shapes and corresponding resonances have not been discussed. This study provides important knowledge about the effects of vehicle seat structural vibration modes on discomfort assessment. The occupied seat resonant frequencies and corresponding vibration modes were measured and comfort test was carried out based on the paired comparison test method. The results show that the ISO 2631-1 (1997) method significantly underestimates the vibration discomfort level around the occupied seat twisting resonant frequencies. This underestimation is mainly due to the ISO suggested location of the accelerometer pad on the seatback. The centre of the seatback is a nodal point at the seat twisting mode. Therefore, it underestimates the total vibration transferred to the occupant body from the seatback. Practitioner Summary:The effects of the vehicle seat structural dynamics have not been discussed in the human body vibration ISO . The results of this research show that the current measurement method suggested by ISO 2631-1 (1997) can significantly underestimate the vibration discomfort level at around the seat structural vibration mode. [ABSTRACT FROM AUTHOR]

Embedded wireless sensors are important components of mobile distributed computing networks, and one of the target applications areas is health care. The preservation of mobility for senior citizens is one of the key issues in maintaining an independent lifestyle. Thus health technologies inside a car can contribute both to safety issues (supervision of driver fitness) as well as healthcare issues by monitoring vitals signs imperceptibly. In this paper, three embedded measurement techniques for non-contact monitoring of vital signals have been investigated. Specifically, capacitive electrocardiogram (cECG) monitoring, mechanical movement analysis (ballistocardiogram, BCG) using piezo-foils and inductive impedance monitoring were examined regarding their potential for integration into car seats. All three sensing techniques omit the need for electroconductive contact to the human body, but require defined mechanical boundary conditions (stable distances or, in the case of BCG, frictional connection). The physical principles of operation, the specific boundary conditions regarding automotive integration and the results during wireless operation in a running car are presented. All three sensors were equipped with local intelligence by incorporating a microcontroller. To eliminate the need for additional cabling, a wireless Bluetooth communication module was added and used to transmit data to a measurement PC. Finally, preliminary results obtained during test drives on German city roads and highways are discussed. [ABSTRACT FROM AUTHOR]

When traveling by train, passengers are exposed to vibration. A well designed seat will attenuate the vibration path to the person in the frequency region where it is the most perceptible, between 3 and 10 Hz. This paper studies the relationship between posture and the human response to vibration. The pressure on the spinal discs has been measured for different postures and it has been found that sitting in a relaxed posture results in a lower intervertebral discs pressure than standing; however, sitting in a upright posture without a suitable back support causes the greatest loading on the spine. Experiments have been performed to examine the perceived discomfort of sitting in a seat with varying backrest angles. Generally, as the backrest is reclined, the discomfort decreases. It has been found that for a tense posture, both the magnitude and frequency of the resonant peak increase comparated to a relaxed posture. This paper concluded that the seat has a great influence on the posture adopted by the passenger, and that a seat with mechanical damping in the 3 to 10 Hz range and a design that encourages a relaxed posture with a slightly reclined backrest will minimize discomfort. [ABSTRACT FROM AUTHOR]

Background: Passive posture variation in vehicles could enable variation in pressure distribution and muscle activity to counter physical fatigue from static seating resulting in more comfort. The difference in posture, however, should not lead to perceived discomfort and aspects of driving should be considered such as operating the steering wheel, pedals and vision in the mirrors., Objective: This study sets out to find out how much postural variation occurs during the driving task and how sensitive is the human body to these changes., Methods: The first experiment was user evaluation and assessed how and when the changes in seat configuration were noticeable to the human body. The second experiment evaluated the influence of varying inclination of the backrest and the seat pan by the rating of typical aspects of driving., Results: The differences in seat configuration during experiment 1, were so small that there was no consistency in the ratings for the same configuration. The most critical feature that restrains the posture is the location of the rear view mirror., Conclusions: The range-of-motion is defined as -1° to +1° for the seat pan and 0° to +1.5° for the backrest based on the results of experiment 2 because of the restraints of the driving task.