Architecture of Computing Systems (Lecture Notes in Computer ...

66 B. Jakimovski, B. Meyer, and E. Maehle
blocked and it can only move within a very limited range. In that case the other legs
within the robot should also synchronize the length of their stance/swing phases.
The self-synchronization that we are introducing in this paper is inspired by firefly
synchronization seen in nature, i.e. when one firefly sees the flashing of another
neighbor firefly it shifts its rhythm of flashing in order to get in synchrony with another
firefly’s flashing. In our robot this would be translated to when one leg changes
(by shortening or prolonging) its own gait, then the other neighboring legs adapt to
this change by shortening or prolonging of their own gait as well. One more rule that
we add to this is that the prolongation takes place only in their stance phase of the leg
and the shortening of the gait takes place only in the swing phase of the leg.
As result, the walking gait of each of the robot’s legs adapts to the change of walking
gait of the neighboring legs, and by that the synchronization of walking gait patterns
is achieved without using global coordination for the change of the gait pattern
by each of the robot’s legs.
The principle of functioning of this concept is shown in Fig. 5. There are two columns:
“Synchro By Prolongation” and “Synchro By Shortening” describing the concept
of self-synchronization when the length of the stance phase is prolonging or
when the length of the swing phase is shortening. Each of the columns has a, b, c, d
figure subparts, where it is shown how the synchronization of the gait patterns takes
place by each of the legs. The lines at the legs show if the leg is in a stance phase –
with “U” shaped line, or is in a swing phase - “∩” shape. The number of dots on the
line represents the duration of the stance or swing phases. For example 3 dots will
represent 3 length units of the swing and stance phase. The length units by the real
robot movement can be translated into degrees of the movement of the leg. For
example length of 3 units may represent 30 degrees of protraction leg movement, or
similar.
For describing our concept we assume that all the legs at start have the same swing
and stance parameters, i.e. 3 length units. In Fig. 5 in column “Synchro By Prolongation”
- subfigure (a) the leg number 3 prolongs its stance phase from 3 length units to
4 length units. In subfigure (b) that follows in the same column, using the firefly inspired
synchronization the neighbor legs numbered 2 and 4 in their stance phase synchronize
their gait length from 3 length units to the length of the gait of leg 3 i.e. 4
length units. In subfigure (c) in the same column, the synchronization wave spreads
further to the other neighbor legs numbered 1 and 5 which also synchronize in their
stance phase their length from 3 length units to 4 length units. In subfigure (d) in the
same column, the leg numbered 0 in its stance phase synchronizes its length parameter
from 3 length units to 4 length units. With this step, the self-synchronization of the
walking gait pattern is finished and the robot continues to walk further with all legs
having gait 4 length units resulting in a greater speed of the robot over the ground. In
Fig. 5 in column “Synchro By Shortening” a self-synchronization of the gait pattern is
shown when the legs are shortening the length of the gait within their swing phases.
In subfigure (a) in the same column, the leg number 2 decreases its gait length in the
swing phase from 3 length units to 2 length units. In the subfigure (b) in the same
column the next cycle is represented where the other neighbor legs numbered as 1 and
3 are decreasing their gait lengths in their swing phases from 3 length units to 2 length