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This thesis proposes a test method for evaluating the perceived vibration which occurs at the driver's hand in automotive steering wheel interface. The objective of the research was to develop frequency weightings for quantifying the human perception of steering wheel hand-arm vibration. Family of frequency weightings were developed from equal sensation curves obtained from the psychophysical laboratory experimental tests. The previous literature suggests that the only internationally standardised frequency weighting Wh is not accurate to predict human perception of steering wheel hand-arm vibration (Amman et. al, 2005) because Wh was developed originally for health effects, not for the human perception. In addition, most of the data in hand-arm vibration are based upon responses from male subjects (Neely and Burström, 2006) and previous studies based only on sinusoidal stimuli. Further, it has been continuously suggested by researchers (Gnanasekarna et al., 2006; Morioka and Griffin, 2006; Ajovalasit and Giacomin, 2009) that only one weighting is not optimal to estimate the human perception at all vibrational magnitudes. In order to address these problems, the investigation of the effect of gender, body mass and the signal type on the equal sensation curves has been performed by means of psychophysical laboratory experimental tests. The test participants were seated on a steering wheel simulator which consists of a rigid frame, a rigid steering wheel, an automobile seat, an electrodynamic shaker unit, a power amplifier and a signal generator. The category-ratio Borg CR10 scale procedure was used to quantify the perceived vibration intensity. A same test protocol was used for each test and for each test subject. The first experiment was conducted to investigate the effect of gender using sinusoidal vibration with 40 test participants (20 males and 20 females). The results suggested that the male participants provided generally lower subjective ratings than the female participants. The second experiment was conducted using band-limited random vibration to investigate the effect of signal type between sinusoidal and band-limited random vibration with 30 test participants (15 males and 15 females). The results suggested that the equal sensation curves obtained using random vibration were generally steeper and deeper in the shape of the curves than those obtained using sinusoidal vibration. These differences may be due to the characteristics of random vibration which produce generally higher crest factors than sinusoidal vibration. The third experiment was conducted to investigate the effect of physical body mass with 40 test participants (20 light and 20 heavy participants) using sinusoidal vibration. The results suggested that the light participants produced generally higher subjective ratings than the heavy participants. From the results it can be suggested that the equal sensation curves for steering wheel rotational vibration differ mainly due to differences of body size rather than differences of gender. The final experiments was conducted using real road signals to quantify the human subjective response to representative driving condition and to use the results to define the selection method for choosing the adequate frequency weightings for the road signals by means of correlation analysis. The final experiment was performed with 40 test participants (20 light and 20 heavy participants) using 21 real road signals obtained from the road tests. From the results the hypothesis was established that different amplitude groups may require different frequency weightings. Three amplitude groups were defined and the frequency weightings were selected for each amplitude group. The following findings can be drawn from the research: • the equal sensation curves suggest a nonlinear dependency on both the frequency and the amplitude. • the subjective responses obtained from band-limited random stimuli were steeper and the deeper in the shape of the equal sensation curves than those obtained using sinusoidal vibration stimuli. • females provided higher perceived intensity values than the males for the same physical stimulus at most frequencies. • light test participants provided higher perceived intensity than the heavy test participants for the same physical stimulus at most frequencies. • the equal sensation curves for steering wheel rotational vibration differ mainly due to differences in body size, rather than differences of gender. • at least three frequency weightings may be necessary to estimate the subjective intensity for road surface stimuli.

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Background Hand-arm vibration (HAV) is an occupational hazard which, cumulatively, leads to hand-arm vibration syndrome (HAVS). Detection and reduction of HAV can help prevent the disease or slow down its progress. Unfortunately, assessment of HAV through direct measurement is difficult due to the high cost of measurement equipment, interruption of work performance, and long travel cost to worksites. An alternative assessment method is through development of an exposure prediction model to identify workplace, tool, and task characteristics which significantly predict HAV exposure. Purpose The purpose of this study is twofold: 1) to determine the extent and nature of previously published scientific journal articles on exposure prediction modeling of HAV through performing a systematic review; and 2) to develop a new exposure prediction model using administrative data to find significant HAV predictors. Methods A systematic review of relevant studies involved humans aged 18 or over, applicable to occupational setting, with vibration measured using tri-axial accelerometer and statistical modeling of the effects of occupational characteristics on measure HAV were identified. Five online bibliographic databases (Medline, CINAHL, Web of Science, Scopus, and EMBASE) were searched using a combined word list of terms under three categories: “occupational diseases”; “Hand-arm vibration”; and “Statistical Modelling”. Two multiple linear regression models predicting average hand-arm vibration exposure over 8 hour day, A(8), were built using enforcement data collected by Ministry of Labour Relations and Workplace Safety Saskatchewan using standard model building method. In addition, GEE was used to account for repeated data collection within workers and worksites. Results In the first manuscript, 7 articles found were deemed relevant. Four studies built regression models, while three used ANOVA to find significant HAV predictors. Examples of significant HAV predictors included: tool age, tool weight, participant, and operating power; the proportion of HAV variance explained varied from 46 to 90%. In the second manuscript, the models based on administrative data explained 16% to 27% of A(8) variance. The included variables were tool power source, vibration control, and job type for the parsimonious model; the comprehensive model has the same variables as parsimonious along with accelerometer attachment method and tool brand. Conclusion HAV prediction through exposure prediction modeling is a relatively new method for assessing occupational HAV. It is feasible to find HAV predictors using low-cost administrative data, and variables such as tool power source, job type, and vibration control make promising predictors. However, the variance explained will be lower than using data collected for research purposes. The significant predictors found in the systematic review can be considered when installing protective measures in the future. The significant predictors found and procedures used from the modeling study can be considered for future HAV exposure prediction modeling studies.

SAMMANFATTNING Bakgrund En del av företagssköterskans arbetsuppgifter är att arbeta förebyggande och se olika typer av problematik som finns hos arbetstagare och arbetsgivare. Omvårdnad av människan ska stå i fokus och rikta sig mot arbetslivet där en säker och god omvårdnad ges (SOU 2011:63). Vibrationsexponering av händer och åtföljande effekter utgör ett betydande arbetsmedicinskt problem där kyrkvaktmästare utgör en exponerad yrkesgrupp. Syfte Syftet med studien var att kartlägga besvär i händer och armar hos kyrkvaktmästare och deras kunskaper kring riskerna med vibrationsexponering. Metod 50 kyrkvaktmästare besvarande två enkäter, en om symtom och en om arbetsmiljö vid vibrationsexponering av handhållna verktyg och dess risker och skador. Resultatet presenterades som deskriptiva data. Resultat Köldkänsla 40 %, vita fingrar 38 % och kramp 38 % var de vanligaste symtomen. Symtom var vanligare bland dem som arbetat minst 10 år i vibrations exponerade arbete. De hade lite kunskap om riskerna med arbetet. Ingen av kyrkvaktmästarna hade blivit erbjuden medicinsk kontoroll enligt Arbetsmiljöverkets föreskrifter. Slutsats Symtom var vanligt förekommande, om medicinska kontroller hade utförts skulle symtomen förmodligen ha upptäcks i ett tidigare skede och inneburit att deras lidande kunde ha minskat. Den medicinska kontrollen hade även inneburit att arbetsgivaren tagit sitt arbetsmiljöansvar för att minimera vibrationsexponeringen (AFS 2005:15). En viktig del i företagssköterskans preventiva arbete är att informera arbetsgivaren om dennes ansvar vid vibrations exponerade arbete och arbetstagarna om riskerna. Nyckelord: hand- arm vibration, riskfaktorer, yrkessjukdomar, yrkesmässig exponering, kyrkvaktmästare / ABSTRACT Background Part of the company nurse's work is to work proactively and identify different types of problems among workers and employers. Nursing of man should be the focus and target the workplace where a safe and good nursing care is provided (SOU 2011:63). Vibration exposure of hands and concomitant effects represent a significant work related problem with care takers from an exposed profession. Aim The aim of the study was to identify hand and arm symptoms in vibration exposure with care takers and their knowledge of the risks associated with vibration exposure. Method Fifty care takers answered two questionnaires, one about symptoms and one about the work environment and vibration exposure of the hand-held tools and its risks and injuries. The results were presented as descriptive data. Results Sensation of cold (40%), white fingers (38%) and cramp (38%) were the most common symptoms. Symptoms were more common among those who had worked at least ten (10) years in vibration exposed work. They had little knowledge of the risks associated with vibration exposure. None of the care takers had been offered medical examination according to the regulation. Conclusion Symptoms were common among care takers; if medical examinations had been carried out the symptoms would probably have been detected at an earlier stage and meant that their suffering could have been reduced. The medical examinations had also meant that the employer would have taken the safety responsibilities to minimize vibration exposure (AFS 2005:15). An important part of the job of the company nurse is to inform the employer of his responsibility for vibration exposure and the workers about the risks. Keywords: hand-arm vibration, risk factors, occupational diseases, occupational exposure, care takers.

Thesis (M.A.)--University of South Florida, 2007. / Title from PDF of title page. Document formatted into pages; contains 55 pages. Includes bibliographical references.

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