Analysis of Passenger Ride Comfort (original) (raw)
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Evaluation of Whole-Body Vibration and Ride Comfort in a Passenger Car
Whole-body vibration transmission influences comfort, performance, and long-term health of the driver. This current study is an objective evaluation of vehicle comfort characteristics based on standard mathematical formulae and frequency analyses. A variety of road types were selected and quantified by using the International Roughness Index (IRI). To assess vibrations transmitted to the passengers, vibration dose values (VDV), kurtosis, frequency response functions (FRF), and power spectral densities (PSD) of the compartment recorded signals were evaluated. SEAT values based on VDV outputs qualified the seat suspension as a vibration isolator, whereas the FRF and PSD quantified that behaviour through frequency analyses. Results indicate that energy concentration is at frequencies lower than 30 Hz. Such low frequency excitations are well attenuated by seat suspension in the vertical direction but are amplified (up to five times in harsh conditions) by a backrest in the fore-aft trend. Signals are amplified beyond 30 Hz, but amplitudes are still very low. It seems that backrest assembly still can be improved to become a better isolator. However, T15 (time to reach severe discomfort), even in harsh conditions, is more than three hours, which exhibits the overall good quality of the vehicle suspension systems. Kurtosis and VDV correlate with IRI and may be used as two objective metrics, together with jury evaluation, to create a vehicle vibration-comfort index in the future.
Analysis of the vertical vibration effects on ride comfort of vehicle driver
Journal of Vibroengineering, 2012
Vehicle vibrations affect the health and comfort of the driver and passengers considerably. The aim of this study is to analyze the effects of vertical vehicle vibrations on the driver. To achieve this goal, a human biodynamic model with 11 degrees of freedom was incorporated into a full vehicle model and this combined human-vehicle model was subjected to the road disturbance. After dynamic analysis of the proposed model, root mean square (RMS) acceleration responses of the human body parts over a certain frequency range were obtained. Physiological effects of the vibrations on the human body were analyzed using the criteria specified in International Organization for Standardization (ISO) 2631. Then, in order to observe the effectiveness of a controller on the vibration isolation of human body, sliding mode controller was applied to the model. Comparison of the vibration effects for the uncontrolled and controlled cases of the human-vehicle model was presented. It can be concluded from the results that sliding mode controller considerably reduces whole body vibrations compared with the uncontrolled case and thereby improves the ride comfort satisfactorily.
Evaluation of Whole-Body Vibration in Automobile on Routine Travel—A Case Study
Studies in Systems, Decision and Control
This paper presents the investigation on the ride comfort of automobile travelling on city roads with a different profile and roughness. The aim of the study was to evaluate and assess the vibration severity on the automobiles travelling in a highway in Konya city according to the data presented in International Standard ISO 2631-1. To reach to this aim, unweighted root mean square value of accelerations in 1/3 octave band at the driver's seat in routine travel speeds in the vertical, lateral and transverse directions have been measured by a sound & vibration hand-held Analyzer. The measurements were conducted in a road with 24 km length during 25 min. The road surface is mainly smooth categorized with a series of bumps, roughness and holes. To evaluate and assess the whole-body vibration severity the achieved data were classified according to three types of road surface characteristics. Measurements of vibration in a long path have shown the vibration severity in the vertical direction was higher than two other directions and acceleration varies between 0.3 and 0.8 ms −2. According to recommendations given in ISO 2631-1, the acceleration 0.8 ms −2 was in uncomfortable ranges. Meanwhile, the dominating acceleration in vertical direction appeared in frequencies lower than 12 Hz. Since the human body is so sensitive to vibrations less than 12 Hz, to lessen the adverse effect of high acceleration it may be recommended to repair the uneven surfaces decrease the bumpy surfaces.
A straightforward approach is presented to investigate the ride dynamic system for a typical rear-drive passenger car. The procedure is based on introducing two main ride excitation sources, i.e., engine/driveline and road inputs, which reduce passengers' comfort. The measured engine fluctuating torques are applied on the coupled model of the driveline and the suspension, to obtain the vehicle body longitudinal vibration. Further, the body vertical response to an average road roughness, is found by employing the quarter-car model. Through the frequency analysis done in this paper, it is shown that we can fastly determine the transfer functions of the systems and also their forced responses at the desired positions, without guessing any initial conditions for the states. The results illustrate that the high frequency inputs, from the engine, are appropriately damped by the current suspension. Hence, the associated vehicle body longitudinal acceleration meets the International Standard Organization (ISO) criteria. This is not the case for the low frequency disturbances, from the road surface irregularities, where the vehicle body vertical acceleration is above the ISO criteria.
Advances in Acoustics and Vibration
This paper shows the results of a study conducted on five different categories of vehicles in a specific test site. The aim was to investigate how the effect of the test site discontinuity determines variations of comfort related to the increase in speed and to the five selected road vehicles of different classes. Measurements were obtained by combining data relating to vibrations in the three reference axes, detected through a vibration dosimeter (VIB-008), and geolocation data (latitude, longitude, and speed) identified by the GPS inside a smartphone. This procedure, through the synchronization between dosimeter and GPS location, has been helpful in postprocessing to eliminate any measurement anomalies generated by the operator. After the survey campaign it was determined that a formulation allows defining a Comfort Index (CI) depending on velocity and five vehicles of different classes. This study showed that the presence of speed bumps, in the test site investigated, appears to ...
Applied Mathematical Modelling, 2013
The paper analyzes the effects of vibrations on the comfort of intercity bus IK-301 users. Evaluation of vibration effects was carried out according to the criteria set out in the 1997 ISO 2631-1 standard for comfort in public means of transport. Comfort is determined for the space of a driver, passenger in the middle part of the bus and passenger in the rear overhang. Also, the allowable exposure time to vibrations in drivers for the reduced comfort criterion was determined according to the 1978 ISO 2631-1 standard. The bus spatial oscillatory model with ten degrees of freedom was developed for the needs of the analysis. Bus excitation was generated applying the Power Spectral Density of the asphalt-concrete road roughness, as described by the H. Braun model. The allowable vibration exposure time for the driver's body decreases as the spring stiffness of the driver's seat suspension system increases. Simulation was performed using the MATLAB software.
Evaluation of Human Discomfort from Combined Noise and Whole-Body Vibration in Passenger Vehicle
International Journal of Automotive and Mechanical Engineering
Exposure to noise and whole-body vibration (WBV) has been a key element in determining comfort levels in transportation systems. In the automotive industry, researchers and engineers continuously work on reducing noise and vibration levels to minimize discomfort. Noise annoyance in vehicles results from structure-borne as well as air-borne noise from vehicle powertrain, tires and aeroacoustics. Whole-body vibration affects vehicle passenger comfort at the seat pan, back rest and feet. The objective of this research is to evaluate the comfort level of seated passengers in a vehicle from noise and whole-body vibration by considering both separate and combined modality. The noise and vibration data were recorded and analysed in two vehicles on the same highway road with four different speeds. The vibration exposure in vehicle were evaluated based on ISO2631-1:1997. Noise exposure was based on A-weighted sound pressure level. The combined discomfort on noise and vibration were quantifie...
Vibration Comfort of the Vehicle Expressed by Seat Effective Amplitude Transmissibility
Mobility and Vehicle Mechanics
Research of the human body vibrations, carried out under controlled laboratory conditions, shows that human body is the most sensitive to vibrations in the frequency range that matches the biomechanical resonance. In the vertical direction, the resonance of the body is approximately 5 Hz, while in the horizontal direction the resonance occurs at frequencies less than 2 Hz. The vibrations of the vehicle have been transferred to the driver and passengers over the seats, which have the ability to attenuate or to amplify vibrations which human body is exposed to while driving. One way to determine the vibration behaviour of the seat is to measure the SEAT (seat effective amplitude transmissibility) factor, which represents the ratio between the vibrations measured on the seat and vibration measured directly on the floor under the seat. Measurement of vibrations in these two positions must be performed simultaneously. If the value of SEAT is less than 1, a seat attenuates vibrations and meets vibrational comfort, the value of SEAT greater than 1 indicates that a seat amplifies vibration, reducing vibration comfort. This paper gives results of SEAT factor investigation done on a hybrid vehicle, for different types of road surface and different modes of driving (electric power and internal combustion engine).
Computational method for predicting the effects of vibrations to acoustical comfort in vehicle cabin
International Journal of Vehicle Noise and Vibration, 2014
One of the main features that attract the customer to purchase a vehicle is the vehicle acoustical and vibration comfort in the vehicle cabin. The exposed noise and vibration will affect the driver's performance in a way that the noise and vibration will distract their vision, which altogether will be stressful to the driver and passenger. Based on previous studies, vibrations are contributed by two main sources, namely the engine transmission and interaction between the tyre and road surface, while the vehicle is moving. Through this study, an approach has been done to estimate numerically the amount of noise influenced by the vibration caused by the interaction between the tyre and road surface. The studies have focused on the observation of the trends of sound quality changes over the changes of engine speeds. At the end of this study, a technical method is provided to show the correlation between the acoustical comfort exposed with the vibration caused by the interaction between tyres and road surface.