Robot Mechanisms and Mechanical Devices Illustrated - Profe Saul

Chapter 7 Walkers 211
knees bend backwards, it is familiar to the designer. One leg at a time can
be built, tested, and debugged and then both attached to a simple plate
for a chassis.
Frame Walking
The third general technique for walking with a legged robot is frame
walking. Frame walking relies on the robot having two major sections,
each with their own set of legs, both sections statically stable. Walking is
accomplished by raising the legs of one frame, traversing that frame forward
relative to the frame whose legs are still on the ground, and then
setting the legs down. The other frame’s legs are then raised and traversed
forward.
The coupling between the two frames usually has a second rotating
DOF to facilitate turning, rather than by adding a rotation in each leg.
Figure 7-11 shows a mechanism for traversing and turning the two parts
of the body. In nature, an inchworm uses a form of frame walking. The
two frames are the front and back sections of the worm. The coupling is
the leg-less section in between. In the case of the inchworm, the coupling
has many degrees of freedom, but two is all that is required if the legs
each have their own ability to move up and down. Unfortunately for
robot designers, the inchworm also has the ability to grasp with its claw-
Figure 7-11 Mechanism for
frame traversing and rotating