Biomedical Engineering Reference
In-Depth Information
result of a complex evolutionary strategy that has tended to make humans walk on
two feet, which is a challenge for balance maintenance. It is impossible to provide
exhaustive knowledge about human walking and many very relevant states of the art
exist in many domains. This chapter aims at providing relevant information about
gait kinematics and dynamics, which should help developers and scientists design
more natural walking facilities in large virtual environments. In most VR simulations
the virtual world is larger than the real walking workspace. The workspace is often
bounded by the tracking area or the display devices. Hence, researchers in VR have
proposed a wide set of systems to make people navigate in wide virtual environments
while maintaining them in restricted real areas. One of the most popular approaches
consists in designing metaphors. Metaphors consist in using one thing to describe
another thing, such as moving an arm laterally to describe a translation of a 3D object
placed in virtual environment.
Another problem is to deliver multisensory feedback that has positive effects on
presence and immersion when navigating in virtual environments. The goal of this
chapter is to provide information to address these two problems.
The first section of this chapter describes kinematics of human walking: global
parameters and joint angles. This section provides the reader with normative refer-
ence data of human gait in straight line and nonlinear walking. It also addresses how
these data change according to various parameters such as gender, age, speed and
orientation. The second part of this chapter provides some knowledge about dynam-
ics of human walking, including the pattern of external forces, their influence on
balance and the muscle activation patterns. Again, reference values and their relation
to other parameters are provided in this section. The last section deals with the com-
parison between ground and treadmill walking. Treadmills are widely used in many
immersive applications that require natural navigation in immersive environments.
However, the way people use this device and perceive the feedback associated with
this device is still unclear. This section tries to provide a synthesis of the knowledge
and discussions about this point. In all the sections, the authors provide an example
of scientific contributions in VR that use this type of knowledge. The goal of this
chapter is thus twofold. Firstly, it provides complementary information to imagine
new systems or improvements of previous works. Secondly, it should help people
better understand the advantages and limits of these previous works.
3.2 Kinematics of Human Walking
Kinematics of human walking has been studied for a long time. In this section, we
give an overview of the most commonly studied kinematic parameters of human
walking. Information about joint kinematics could be used:
•
to create more realistic camera displacements when navigating in VR [
70
] so that
classical linear camera displacements could be replaced by more natural motions,
in order to enhance the feeling of naturally walking in VR,
