INJURY CONTROL FOR WHEELCHAIR OCCUPANTS - Injury Biomechanics and Control: Optimal Protection from Impact - page 266

For D = 0 . 2 m, the optimal control without pre-action is defined by

− 10 . 7g, 0 ≤ t ≤ 0.127 s,

u 0 (t) = (8.13)

0, t > 0 . 127 s,

and the pre-acting optimal control has the form

− 7 . 0g, − 0 . 047 s ≤ t ≤ 0.147 s,

u 0 (t) = (8.14)

0, t > 0 . 147 s.

The optimal pre-action time t 0 inEq.8.14isequalto0 . 047 s.

8.3 SIMULATION USING MADYMO

8.3.1 Model Structure and Parameters

A multibody model was used for the simulation and optimization (Fig. 8.2).
The system involves vehicle 1, platform 2, impact isolator 3, wheelchair 4,
wheelchair tiedown system 5, occupant 6, and occupant's restraint system 7.
The vehicle, platform, and wheelchair are regarded as rigid bodies. The
vehicle moves along a horizontal straight line.
The platform can move relative to the vehicle along the longitudinal
axis coinciding with the line of motion of the vehicle. The contact plane
(floor) of the platform is parallel to the vehicle's floor and the plane of the
road. The platform has a vertical stanchion to which the upper end of the

1 - Vehicle
2 - Platform
3 - Isolator
4 - Wheelchair
5 - Tiedown system
6 - Occupant
7 - Occupant
restraint system

FIGURE 8.2 Model of an occupied wheelchair based on a shock-isolated platform.