Biomedical Engineering Reference
In-Depth Information
Table 2. Hexapodal primary gaits and description
Gait pattern
Pattern description
Ipsilateral legs
Contralateral legs
Pronk
in phase
in phase
Pace
in phase
half cycle out
Lurch
half cycle out
in phase
Tripod
half cycle out
half cycle out
Inchworm
one-sixth cycle out
in phase
Metachronal
one-sixth cycle out
half cycle out
Caterpillar
one-third cycle out
in phase
Rolling tripod
one-third cycle out
half cycle out
Current arrangement of system parameter
matrices for the thresholds, synaptic weights,
initial membrane potentials are θ,
W
and
M
(0),
respectively, as shown below, displays a short
stage converging to the rolling tripod period. An
algorithm is required to acquire the symmetric
threshold matrix (see Table 3).
The flexors of different legs of the rolling
tripod gait fire in the order of
RL, FR, ML, RR,
FL, MR
; the corresponding extensors fire in the
order of
FL, RR, MR, FR, RL, ML
. A snapshot
phase of each macroneuron in the flexor layer is:
RL=
0
, ML=
3
two macroneurons while
zero
means this clone's
threshold is
zero
. Otherwise
zero
means there is
no connection between two macroneurons.
There is an optimal range of initial membrane
potential configuration for a gait pattern. If a clone
of a macroneuron is designed to fire at start, it
should have initial value as,
(
0
if
w
=
0
and
=
0
ij
ij
M
(
0
∈
ij
(
if
w
=
0
and
=
1
ij
ij
If it is idle at start, then it is assigned with the
following initial value,
5
, FR=
6
1
.
Based on the given hexapod locomotion model,
the matrices of activity thresholds, weights and
initial membrane potentials of all interacting
clones in the rolling tripod gait can be created
for numerical simulation (Figure 10c~f) with the
computational model developed in the section of
OBB modules.
Any parameter with subscript
ij
means that it
belongs to macroneuron
i
which is connecting with
macroneuron j. In
W
matrix, the diagonal values
are negative feedbacks of the clones themselves.
In θ matrix, the value of
zero
has different signifi-
cance. If the diagonal symmetry position of
zero
is
one
, then there is a connection between these
1
, FL=
3
2
, RR=
2
1
, MR=
6
(
−
0
if
w
=
0
and
=
0
ij
ij
M
(
0
∈
ij
(
0
if
w
=
0
and
=
1
ij
ij
The initial membrane potential of a clone
should have a scope of 2
w
ij
around the centre point
of its threshold. This configuration guarantees
that all clones of all macroneurons do not have
convergent stage such that the starting state of
the oscillation system is immediately within an
oscillation cycle without possible deadlock occur-
ring due to unsuitable choice of initial potentials.
A random choice of the membrane potentials is
allowed subject to an initial convergent period
before entering an oscillation cycle.
Search WWH ::
Custom Search