Biomedical Engineering Reference
In-Depth Information
0.3
0.25
0.2
0.15
0.1
0.05
0
0
0.05
0.1
0.15
0.2
0.25
0.3
(e)
Time (s)
FIGURE 13.37, cont'd
13.7 THE 1995 LINEAR HOMEOMORPHIC
SACCADIC EYE MOVEMENT MODEL
In the previous section, we presented a linear model of the oculomotor plant developed
by linearizing the force-velocity curve. We then derived a linear differential equation to
describe the system. Here we reexamine the static and dynamic properties of muscle in
the development of a new linear model of oculomotor muscle. With the updated linear
model of oculomotor muscle, the model of the oculomotor system will also be updated.
13.7.1 The Linear Muscle Model
The updated linear model for oculomotor muscle is shown in Figure 13.38. Each of the
elements in the model is linear and supported with physiological evidence. The muscle is
modeled as a parallel combination of viscosity
B
2
and series elasticity
K
se
, connected to
the parallel combination of active-state tension generator
F
, viscosity element
B
1
, and length
tension elastic element
x
2
describe the displacement from the equilib-
rium for the stiffness elements in the muscle model. The only structural difference between
this model and the previous oculomotor muscle model is the addition of viscous element
K
lt
. Variables
x
1
and
B
2
and the removal of passive elasticity
B
2
is
vitally important to describe the nonlinear force-velocity characteristics of the muscle, and
the elastic element
K
pe
. As will be described, the viscous element
is unnecessary.
K
pe
