Database Reference
In-Depth Information
Table 2: The 7-bit motion byte
Coordination Space 1
st
D
Space 2
nd
D
Space 3
rd
D
Bits 1
Bits 2 + 3
Bits 4 + 5
Bits 6 + 7
1 = motion
1 0 = pitch angle
increasing
1 0 = roll angle
increasing
1 0 = spin angle
increasing
0 = rest
0 1 = pitch angle
decreasing
0 1 = roll angle
decreasing
0 1 = spin angle
decreasing
0 0 = no change
in pitch angle
0 0 = no change
in roll angle
0 0 = no change
in spin angle
1 1 = not relevant
1 1 = not relevant
1 1 = not relevant
robot, that is, a robot with joints that have only one degree of freedom, can be represented
by a 3-bit motion byte only.
The two bits representing the time aspect are in fact superfl uous since the time aspect
can be computed on the basis of the time unit rate (sampling frequency). It is possible,
however, to extend information on the time aspect (acceleration and deceleration of ve-
locity) as redundancy data. In this case the motion byte will need
ninebits per limb per
time unit
. Bits 8 and 9 will represent acceleration (1 0), deceleration (0 1) and no change
in velocity (0 0).
Motion Components
Space
The space component of motion with its dimensions and axes is as described above.
Time
While the time component is redundant data, as mentioned above, because it can be
computed based on the time unit rate (sampling frequency) by the formula V * T = S, it can
be represented by two bits (bits 8-9), as follows:
Bits 8-9 represent the
velocity
of the motion performed. They express a single unit
change in the velocity at which the limb is moving, representing three possible situ-
ations: acceleration, deceleration, and maintaining current velocity.
•
Coordination
The coordination component defi nes the
state change from rest to motion
, and vice
versa; that is, it deals with a body's “
entering
or
exiting
” an active category. The one-bit
coordination component is thus used to express two states:
motion
and
rest
. Here, it is
necessary to pinpoint precisely the beginning and end of each movement, according to the
following guidelines.
Movement ends (“
exit
”) when velocity goes from any value to zero, and the joint's
opening angle freezes in place.
•
