Frequency weighting for the evaluation of steering wheel rotational vibration

The human perception of rotational hand-arm vibration has been investigated by means of a test rig consisting of a rigid frame, an electrodynamic shaker unit, a rigid steering wheel, a shaft assembly, bearings and an automobile scat. Fifteen subjects were tested while seated in a driving Posture. Four equal sensation tests and one annoyance threshold test were performed using sinusoidal excitation Lit 18 frequencies in the range from 3 to 315 Hz. In order to guarantee the generality of the equal sensation data, the four tests were defined to permit checks of the possible influence of three factors: reference signal amplitude, psychophysical test procedure and temporary threshold shift caused by the test exposure. All equal sensation tests used a reference sinusoid of 63 Hz at either 1.0 or 1.5 m/s(2) r.m.s. in amplitude. The four equal sensation curves were similar in shape and Suggested a decrease in human sensitivity to hand-arm rotational vibration with increasing frequency. The slopes of the equal sensation Curves changed at transition points of approximately 6.3 and 63 Hz. A frequency weighting, called was developed for the purpose of evaluating steering wheel rotational vibration. The proposed W., has a slope of 0 dB per octave over the frequency range from 3 to 6.3 Hz, a slope of -6dB per octave from 6.3 to 50 Hz, a slope of 0 dB per octave from 50 to 160 Hz and a slope of - 10 dB per octave from 160 to 3 15 Hz. W-s provides a possible alternative to the existing W-h frequency weighting defined in International Standards Organisation 5349-1 (2001) and British Standards Institution BS 6842 (1987). Relevance to industry For the manufacturers of tyres, steering systems and other vehicular components the proposed W-s frequency weighting provides a more accurate representation of human perception of steering wheel rotational vibration than the Wh weighting of ISO 5349-1 and BS6842. (C) 2004 Elsevier B.V. All rights reserved.