Control of foot placement to counteract perturbations during walking

Walking and maintaining balance during walking seems effortless, however, for
people with impaired sensory or motor systems it can be a large effort. For
these people training could be an opportunity to increase their walking ability.
Robotic devices can provide people with the necessary support during training
and are suitable for intensive and repetitive training. For the robot to be
able to assists people with maintaining balance during walking in a correct and
natural way a good understanding and insight in balance control is necessary.
At the moment there is no experimental data that provides us with this
knowledge. Therefore we designed an experiment based on the stepping strategy
which is the most important mechanism to control balance. With this experiment
the control of foot placement to counteract perturbations during walking is
studied. Data from this experiment will show how subjects respond to
perturbations and could give information about the foot placement that is
needed to counteract the perturbations and maintain balance.
In this way we will gain more knowledge and understanding about the balance
control mechanism which in the end can be used in developing a model to control
robotic devices.

Primary Objective:
Assess the effect of walking velocity and the effect of timing, direction and
velocity of sudden platform perturbations on foot placement to control balance
during walking.

Secondary Objective(s):
• Determine the relation between the deviation and velocity of the centre of
mass (CoM) with the step width, step length and step time
• Investigate the coupling between foot placement in the frontal and the
sagitalsagittal plane.
• Investigate muscle activation to determine the contribution of arm
movements and single muscles to balance control.

This study is designed as a cross-sectional intervention study to assess foot
placement to control balance during normal and perturbed walking of healthy
human subjects. All subjects participate in one session which will take
approximately 3,5 hours. During the session the effect of different platform
perturbations on foot placement used to control balance during walking will be
tested. The perturbations vary within each experiment, but will be the same for
each subject.
The result of this study can be used to reveal a part of controlling balance
during walking .

In this study there is one intervention. The balance of the subjects will be
disturbed during walking in a balance experiment. This is done bij translations
of a motion platform

Subjects will participate in one session which will take approximately 3 hours.
During this session the subject will be asked to walk on a treadmill for ten
trials. In two trials the subject will walk normally at 2 km/h and 4km/h. In
the other eight trials the subject will walk at 2km/h or 4 km/h and will be
perturbed by using platform movements of different velocities in different
directions and during different phases of the gait cycle. Trials will be
randomised and in between trials subjects will receive time to rest.
In this study there is a risk for the subjects to lose their equilibrium.
Therefore the subjects will be wearing a safety harness during the experiment
that is attached to the ceiling and which will prevent the subjects from
falling.
Participants will have no direct benefit from taking part in this study.