Equal Annoyance Contours for Steering Wheel Hand-arm Vibration

The steering wheel is one of the primary sensory inputs for vehicle vibration while driving. Past research on hand-arm vibration has focused on a hand gripping a rod or a hand on a flat plate. Little work has focused on the perception of vibration felt through an automotive steering wheel. This paper discusses the investigation conducted at Ford's Vehicle Vibration Simulator Lab to develop equal annoyance contours for hand-arm vibration. These contours were developed for four different degrees-of-freedom: vertical, lateral, longitudinal and rotation about the steering wheel center. Rotation about the steering wheel is commonly induced by a 1^st order tire non-uniformity force and imbalance of the wheel/tire. These 1^st order excitation forces generate vibration in the frequency range of 8-20 Hz. Using a method-of-adjustment evaluation procedure, equal annoyance contours were developed using pure sinusoids over this frequency range for two levels of reference vibration (0.8 m/s² and 1.6 m/s² @ 14 Hz). These equal annoyance contours showed a small vibration level effect and also indicated a reduced annoyance as the frequency is increased.

The equal annoyance contours for the three translational degrees-of freedom were investigated over the frequency range of 10-64 Hz using a single reference signal of 1 m/s² @ 25.5 Hz. All contours showed a general trend of decreasing annoyance as frequency increased with the effect being less pronounced in the 40-64 Hz frequency range. It is also shown that the frequency weighting observed is in better agreement with Giacomin's W_s weighting than, W_h, as defined in ISO 5349-1 and BS 6842 standards for hand-arm vibration.