
184 Virtual Reality: Concepts and Technologies
active part, most often corresponding to a discretisation procedure (Colgate &
Shenkel, 1994);
• For the second, we shall talk about the objective of “transparency’’. The purpose
is to get close to the ideal system which is characterised as:
f
h
= h
f
· f
e
v
h
= h
v
· v
e
(9.1)
where h
f
and h
v
represent the force scaling and speed scaling respectively. Such an
objective implies good position tracking, i.e. x
e
≈ x
h
, at least in free mode;
• The third criterion corresponds to the transient state of the system and helps to
define the relative values between stiffness and damping of the coupling equaliser
between the control ...