Human comfort and motion under simulated vibration exposure of mobile machinery

In order to develop more user-friendly mobile machinery, more information on the connection between the human comfort experience, human-seat interaction, and measurable quantities, like the motion of the operator's seat, are needed. In this paper we describe a study on the mechanical response and the subjective comfort feeling of a human exposed to high level vibration. Experimental tests were accomplished in a laboratory motion platform, which simulated the vibration excitation that an operator experiences in a heavy mobile work machine. The test excitations were based on field measurements and included such activities as cultivation, moving in forest and on gravel road. Vibration responses of 23 test subjects were measured using four tri-axial accelerometers. The test subjects were equipped with heart rate monitor and they evaluated the vibration exposure based on a five scale comfort criteria and described their subjective experience. R.M.S-valucs, based on the ISO 2631-1 standard, were calculated from the acceleration data from the floor, seat and head of the test subjects. The human comfort is a sum of many different variables, and the analysis of the test data is complicated due to individual differences. In this paper we introduce the findings concerning the relationship between the measurable quantities and the comfort feeling based on the experimental tests. Copyright