The basic gallop is illustrated by Whisker, the pointer.
This is a 4-step gait, shown here as LR, RR, LF, then RF.
The leg ordering is very different from the walk and trot.
The RF leg is actually the "leading" leg here. The characteristic of this gait
is that the leading leg bears the weight of the body over longer periods of time
that any other leg, and is more prone to fatique and injury. The single suspension
phase [positions 13-15] is initiated by catapaulting the entire body off the leading
leg [positions 10-12].
The force comes from the back legs pushing off onto the non-leading front leg, and
then onto the leading leg [positions 3-8]. Notice the length of time the back legs
There is a postion where all 4 legs are under the body, and others where either the
2 front or 2 rear legs are extended away from the body, but none where both fronts and
both rears are extended simultaneously (as for the next gallop shown below).
This gives a degree of rocking to the body, as the
relative position of the COG moves forward and backwards.
The figure at the left is of a real dog shown in the same position of the gallop
as the schematic dog of position 11.
Note how all of its weight bears down on its right-front paw, which is bent heavily to absorb
the shock, and that the right-front elbow is locked in a straight extension [in both figures],
so the leg doesn't collapse under the load.
For comparison purposes, this is similar to footfall in the
The anatomy of the lower leg of the horse is heavy on
tendon, with very little muscle, and with the tendon bending around the
fetlock bone as a pivot point.
In running animals, upwards to 70% the energy of each stride is stored in the muscles and
stretching of the leg tendons, to be released during the following stride.
Galloping is too much to think about for a robot at this point.