抄録
The transportation of wheelchair-bound passengers by specially equipped cars or buses has expanded wheelchair users' area of activity. However, vehicles equipped with the existing wheelchair transporting apparatus have been described as uncomfortable because the wheelchair is rigidly fixed on the floor, and vibration is directly transmitted to the occupant. In designing such apparatus, it is necessary to control the vibration and improve comfort. Improving comfort is difficult because driving conditions, wheelchair users' constitution and wheelchair types vary greatly. Therefore, modeling the system and simulating its quantitative movement is an effective design support method. The purpose of this study is to examine the vibration characteristics of the system and construct a vibration simulation model.
A modal experiment with a vibration generator was performed. The vibration transmitted to occupant was measured for an input vibration from 1 Hz to 15 Hz, and four natural modes of the system were clarified. Then, the occupant-wheelchair system was modeled as a two-dimensional seven-degrees-of-freedom model consisting of masses, springs and dampers. The occupant was modeled in five segments and the wheelchair in one, and then the equation of motion of the system was formulated. The unknown physical characteristics of the elements were clarified with the modal properties obtained through the modal experiment. A simulation in a natural mode was carried out, and its result agreed with the actual movement of the occupant recorded on videotape in the experiment. The validity of the model was thus proved. In addition, model simulations were run by varying the physical parameters. Because it resulted in changes of the movement in proportion to the parameter variation, the constructed model was verified to be valuable for design purposes.
