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Comfort and Quality
Published in Motoyuki Akamatsu, Handbook of Automotive Human Factors, 2019
The weighting curve of frequencies and the correlation between the evaluation part/direction and the weighting coefficient of frequencies/direction magnification are determined in ISO 063 and ISO 5349, because the frequency properties of the sense or sensation of vibration differs according to the part of the human body, or the direction of the oscillation. Note that in evaluation methods for hand-transmitted vibration, the range of evaluation goes up from 8 to 1,000 Hz, and in methods for the rest of the whole of the body rises from 0.5 to 80 Hz. As to the weighting coefficient of hand-transmitted vibration (Wh), although the direction magnification between each direction and the correction coefficient for vibration of the entire body is not determined, a study that shows that it should be from 0.12 to 0.26 in relation to the surface of the seat (Morioka, 2007).
Basic principles
Published in Michael Talbot-Smith, Audio Engineer's Reference Book, 2012
higher figure considerably. Often the lowest frequencies are detected as much by sensing the vibrations they cause rather than their audible effects. The human ear is not equally sensitive to all frequencies; those from around 300 to 6000 Hz are the best perceived and, therefore, appear loudest, whilst higher and lower frequencies of equal amplitude seem less obvious. A frequency weighting was introduced in an attempt to measure noise in the same way that the ear perceives it and this is called the A weighting curve. Measurements made using this weighting are often indicated as dB(A), but increasingly where measurements of environmental noise are made, the use of A weighting is assumed, and the readings taken are just given in decibels (dB). The response of the A weighting network is shown in Figure 1.69. Other weightings exist; none has the universal usage of the A weighting, although C weighting is specified in some standards, particularly in the USA. Almost every meter measuring SPL will give a reading in dB(A), which for a pure tone of, say, 125 Hz at pressure level of 90 dB will read 73.9 dB(A) (from Figure 1.69 ). In addition to SPL, many other parameters have been devised in an attempt to produce a singlenumber result for a particular type of noise. Integration of the SPL with time, to produce the averaged SPL over a given time interval, is one of the most widely used and is known as the equivalent continuous level (Leq : Leq,T D log10
Human Hearing and Noise Criteria
Published in David A. Bies, Colin H. Hansen, Carl Q. Howard, Engineering Noise Control, 2018
David A. Bies, Colin H. Hansen, Carl Q. Howard
Attempts to present a single decibel number to describe the annoyance of environmental noise has led to the use of weighting networks, whereby the level of noise is adjusted as a function of frequency in an attempt to replicate how an average normal ear would hear. These weighting networks are more suitable for some types of noise than others. Most environmental and occupational noise measurements are taken using the A-weighting network. This is because the A-weighting curve is a good approximation of the ear response to low-level sound such as may be typical of environmental noise and it seems to be related to hearing damage risk in high noise level environments, even though the apparent loudness of high-level noise is closer to the C-weighting curve.
Equivalent magnitude-dependent discomfort under vertical vibration up to 100 Hz
Published in Ergonomics, 2022
Jiewei Lin, Meng Li, Zefeng Lin, Jian Wang, Xiangde Meng, Junhong Zhang
Frequency weightings obtained in this study are formed with inverted and normalised equivalent comfort contours (Figure 8). It is shown that the frequency weightings formed at higher magnitudes are in the same trend as the frequency weighting (Wk) recommended by the current ISO standard (International Organization for Standardization 1997). However, due to the effect of vibration magnitude on equivalent comfort contours, the frequency-dependence of frequency weightings is also affected by the magnitude of vibration. Similar evidences can be found in Huang’s study (Huang and Zhang 2019) and Morioka’s study (Morioka and Griffin 2006). It can be inferred that a certain frequency weighting curve is not appropriate to evaluate the discomfort caused by different vibration magnitudes, especially for vibrations at high magnitudes.
Towards comfort-optimal trajectory planning and control
Published in Vehicle System Dynamics, 2019
Marlies Mischinger, Martin Rudigier, Peter Wimmer, Andreas Kerschbaumer
The planned trajectory was used for simulation with two different controller models and the simulation results were compared to test drives. A validated vehicle model was used in the simulation. Obviously the used vehicle has influence on the comfort, but through the use of the same vehicle the results are comparable. Eriksson et al. [20] differentiate between local and average comforts. Local comfort takes maximum accelerations and jerks into account. Average comfort uses the comfort related part of ISO 2631-1. In this work, local comfort (only max. acceleration) is used during planning of the trajectories. For the comparison of the average comfort of trajectories the ISO 2631-1 [21] is used. Since the focus in this work is the assessment of trajectories only the lateral accelerations are considered in the approach. Therefore, the following steps are carried out: first, accelerations are filtered with the frequency-weighting-curve of ISO 2631-1. Then the weighted signal is taken to the power of two and integrated following the formula: is the time range of measurement; is the frequency weighting function ISO 2631-1; is the filtered lateral acceleration; is the root mean square of .
Integration of car-body flexibility into train–track coupling system dynamics analysis
Published in Vehicle System Dynamics, 2018
Liang Ling, Qing Zhang, Xinbiao Xiao, Zefeng Wen, Xuesong Jin
Figure 12 illustrates the frequency weighting curves for the ride comfort indices defined by the Sperling method and the standard of UIC513. It shows the frequency range of interest of the Sperling lateral comfort index is 0.5–26 Hz, while the peak of the weighting curve is 5.4 Hz. According to the results shown in Figures 9(b,c), the difference between the lateral accelerations obtained by the rigid and flexible models in the range of 0.5–26 Hz is not large. This leads to the minor difference occurring in the Sperling lateral comfort indices shown in Figure 11(a). For the Sperling vertical comfort index, the dominating frequency range of interest is 0.5–20 Hz, with the weighting curve peak of 5.9 Hz. Figure 8(b,c) shows that the vertical accelerations in the range of 8–20 Hz obtained by using the flexible model are much greater than that calculated by using the rigid model, which explains the results shown in Figure 11(b).