Biomedical Engineering Reference
In-Depth Information
was pulled up and when the walker goes down stairs, the backward foot is pulled up.
However, this method was not successful because it caused walker instability.
Later a 6 DOF motion platform was applied in a final version of the Virtual
Perambulator. In it, a user walks in a hoop frame. The walker stood on the top plate
of the motion platform. Pitch and heave motion of the platform were used. When
the walker stepped forward to climb up a stair, the pitch angle and vertical position
of the floor increased. After finishing climbing motion, the floor went back to the
neutral position. When the walker steps forward to go down a stair, the pitch angle
and vertical position of the floor decreases. This inclination of the floor is intended to
present height differences between the feet. The heave motion is intended to simulate
vertical acceleration. However, this method appeared to fail in simulation of stairs.
The major reason was that the floor was flat.
A possible method of creation of height difference between the feet is application
of two large manipulators. The BiPort is a typical example. A 4 DOF manipulator
driven by hydraulic actuators is connected to each foot. The major problem with this
method is that how the manipulators trace the turning motion of the walker. When
the walker turns around, the two manipulators may interfere each other.
The “GaitMaster” is a locomotion interface that simulates an omni-directional
uneven surface. The project started in 1999 [ 12 ]. The core elements of the device
are two 6 DOF motion-bases mounted on a turntable. Figure 9.10 illustrates basic
configuration of the GaitMaster. A walker stands on the top plate of the motion-base.
Fig. 9.10
Structure of Gait-
Mater
 
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