Hand-arm equal sensation curves for steering wheel rotational vibration

The present study has established equal sensation curves for steering wheel handarm rotational vibration. Psychophysical response tests of 20 participants were performed using the category-ratio Borg CR10 scale procedure. The test stimuli used were sinusoidal vibrations at 22 third octave band centre frequencies in the range from 3 to 400 Hz, with amplitudes in the range from 0.06 to 30 m/s2 r.m.s. A multivariate regression analysis was performed on the mean Borg CR10 intensity values as a function of the two independent parameters of the vibration frequency and amplitude. The results suggested a nonlinear dependency of the perceived intensity on both the steering wheel rotational vibration frequency and amplitude. A sixth-order polynomial model has been proposed as a best fit regression model

Human Perception of Diesel Engine Idle Vibration

While the human perception of diesel engine noise has been the subject of numerous studies, the perception of the vibrational disturbance reaching the driver has not previously been investigated. This contribution presents the results of a recent research study performed at Sheffield University which analysed the nature of diesel engine idle, and modelled the associated human growth function. The results have shown that the largest component of diesel idle irregularity arriving at the steering wheel is amplitude modulation of the firing frequency and that the human subjective response grows with a power exponent greater than 1.0 for modulation values greater than 0.2

Analysis of variations in diesel engine idle vibration

The variations in diesel engine idle vibration caused by fuels of different composition and their contributions to the variations in steering wheel vibrations were assessed. The time-varying covariance method (TV-AutoCov) and time-frequency continuous wavelet transform (CWT) techniques were used to obtain the cyclic and instantaneous characteristics of the vibration data acquired from two turbocharged four-cylinder, four-stroke diesel engine vehicles at idle under 12 different fuel conditions. The analysis revealed that TV-AutoCov analysis was the most effective for detecting changes in cycle-to-cycle combustion energy (22.61 per cent), whereas changes in the instantaneous Values of the combustion peaks were best measured using the CWT method (2.47 per cent). On the other hand, both methods showed that diesel idle vibration was more affected by amplitude modulation ( 12.54 per cent) than frequency modulation (4.46 per cent). The results of this work suggest the use of amplitude modulated signals for studying the human subjective response to diesel idle vibration at the steering wheel in passenger cars

Effect of automobile operating condition on the subjective equivalence of steering wheel vibration and sound

The research described here was performed to define curves of subjective equivalence between steering wheel rotational vibration and sound using stimuli from different automobile operating conditions. The steering wheel acceleration stimuli were summarised in terms of the unweighted and Wh weighted r.m.s. values, while the sound stimuli were summarised in terms of the unweighted sound pressure level in decibels, the A-weighted sound pressure level in decibels, the Stevens Mark VI loudness in sones, the Stevens Mark VII loudness in sones and the Zwicker loudness in sones. The results suggest that both the statistical properties of the stimuli, and the choice of metric, effect the shape of the equivalence curve. No single combination of vibration and sound metric produced a family of curves which were separated by less than a single psychophysical just noticeable difference

Facilitating the driver detection of road surface type by selective manipulation of the steering-wheel acceleration signal

Copyright @ 2012 by Institution of Mechanical Engineers.Previous research has investigated the possibility of facilitating the driver detection of road surface type by means of selective manipulation of the steering-wheel acceleration signal. In previous studies a selective increase in acceleration amplitude has been found to facilitate road-surface-type detection, as has selective manipulation of the individual transient events which are present in the signal. The previous research results have been collected into a first guideline for the optimization of the steering-wheel acceleration signal, and the guideline has been tested in the current study. The test stimuli used in the current study were ten steering-wheel acceleration-time histories which were selected from an extensive database of road test measurements performed by the research group. The time histories, which were all from midsized European automobiles and European roads, were selected such that the widest possible operating envelope could be achieved in terms of the r.m.s. value of the steering acceleration, the kurtosis, the power spectral density function, and the number of transient events present in the signal. The time histories were manipulated by means of the mildly non-stationary mission synthesis algorithm in order to increase, by a factor of 2, both the number and the size of the transient events contained within the frequency interval from 20 Hz to 60Hz. The ensemble, composed of both the unmanipulated and the manipulated time histories, was used to perform a laboratory-based detection task with 15 participants, who were presented the individual stimuli in random order. The participants were asked to state, by answering 'yes' or 'no', whether each stimulus was considered to be from the road surface that was displayed in front of them by means of a large photograph on a board. The results suggest that the selectively manipulated steering-wheel acceleration stimuli produced improved detection for eight of the ten road surface types which were tested, with a maximum improvement of 14 per cent in the case of the broken road surface. The selective manipulation did lead, however, to some degradation in detection for the motorway road stimulus and for the noise road stimulus, thus suggesting that the current guideline is not universally optimal for all road surfaces

Non-linear dependency of the subjective perceived intensity of steering wheel rotational vibration

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2009 ElsevierThe present study has established equal sensation curves for steering wheel hand-arm rotational vibration. Psychophysical response tests of 20 participants were performed in a steering wheel rotational vibration simulator using the category-ratio Borg CR10 scale procedure for direct estimation of perceived vibration intensity. The test stimuli used were sinusoidal vibrations at 22 third octave band centre frequencies in the range from 3 to 400 Hz, with acceleration amplitudes in the range from 0.06 to 30 m/s(2) r.m.s. A multivariate regression analysis was performed on the mean perceived intensity Borg CR10 values as a function of the two independent parameters of the vibration frequency and amplitude. The results suggested a non-linear dependency of the subjective perceived intensity on both the steering wheel rotational vibration frequency and amplitude. The equal sensation curves were found to be characterised by a decreased sensitivity to hand-arm vibration with increasing frequency from 10 to 400 Hz, but by an increased sensitivity with increasing frequency from 4 to 10 Hz. A 6th order polynomial model has been proposed as a best fit regression model from which the equal sensation curves for steering wheel rotational vibration are derived.Relevance to industry: For the manufactures of automobiles, steering systems and other automobile components this study provides a mathematical model from which one or more new frequency weightings for the use in evaluating the perceived intensity of steering wheel rotational vibration are derived. (C) 2008 Elsevier B.V. All rights reserved

A survey study of steering wheel vibration and sound in automobiles at idle

Copyright @ 2009 Engineering Integrity SocietyThis work is supported by Shell Global Solutions UK for their sponsorship of this research as part of the activities of the EFII3 project

The effect of disorder on the free-energy for the Random Walk Pinning Model: smoothing of the phase transition and low temperature asymptotics

We consider the continuous time version of the Random Walk Pinning Model (RWPM), studied in [5,6,7]. Given a fixed realization of a random walk Y$ on Z^d with jump rate rho (that plays the role of the random medium), we modify the law of a random walk X on Z^d with jump rate 1 by reweighting the paths, giving an energy reward proportional to the intersection time L_t(X,Y)=\int_0^t \ind_{X_s=Y_s}\dd s: the weight of the path under the new measure is exp(beta L_t(X,Y)), beta in R. As beta increases, the system exhibits a delocalization/localization transition: there is a critical value beta_c, such that if beta>beta_c the two walks stick together for almost-all Y realizations. A natural question is that of disorder relevance, that is whether the quenched and annealed systems have the same behavior. In this paper we investigate how the disorder modifies the shape of the free energy curve: (1) We prove that, in dimension d larger or equal to three 3, the presence of disorder makes the phase transition at least of second order. This, in dimension larger or equal to 4, contrasts with the fact that the phase transition of the annealed system is of first order. (2) In any dimension, we prove that disorder modifies the low temperature asymptotic of the free energy.Comment: 18 page

Human emotional response to steering wheel vibration in automobiles

This is the post-print (final draft post-refereeing) version of the final published paper that is available from the link below. Copyright @ 2013 Inderscience Enterprises Ltd.This study investigates what form of correlation may exist between measures of the valence and the arousal dimensions of the human emotional response to steering wheel vibration and the vibration intensity metrics obtained by means of the unweighted and the frequency weighted root mean square (rms). A laboratory experiment was performed with 30 participants who were presented 17 acceleration time histories in random order and asked to rate their emotional feelings of valence and arousal using a self-assessment manikin (SAM) scale. The results suggest a highly linear correlation between the unweighted, Wh weighted and Ws weighted vibration intensity metrics and the arousal measures of the human emotional response. The results also suggest that while vibration intensity plays a significant role in eliciting emotional feelings, there are other factors which influence the human emotional response to steering wheel vibration such as the presence of high peaks or high frequency band amplitudes