Robot Mechanisms and Mechanical Devices Illustrated - Profe Saul

216 Chapter 7 Walkers
Walkers have inherently more degrees of freedom, which increases
complexity and debug time. As will be investigated in the chapter on
mobility, walkers deal with rugged terrain very well, but may not actually
be the best choice for a mobility system. Roller walkers offer the
advantages of both walking and rolling and in a well thought out design
may prove to be very effective.
Walkers have been built in many varieties. Some are variations on
what has been presented here. Some are totally different. In general, with
the possible exception of the various roller walkers, they share two common
problems, they are complicated and slow. Nature has figured out
how to make high-density actuators and control many of them at a time
at very high speed. Humans have figured out how to make the wheel and
its close cousin, the track. The fastest land animal, the cheetah, has been
clocked at close to 100km/hr. The fastest land vehicle has hit more than
seven times that speed. Contrarily, a mountain goat can literally run
along the face of a steep cliff and a cockroach can scramble over terrain
that has obstacles higher than itself, and can do so at high speed. There
are no human-made locomotion devices that can even come close to a
goat’s or cockroach’s combined speed and agility.
Nature has produced what is necessary for survival, but nothing more.
Her most intelligent product has not yet been able to produce anything
that can match the mobility of several of her most agile products. Perhaps
someday we will. For the person just getting started in robotics, or for
someone planning to use a robot to do a practical task, it is suggested to
start with a wheeled or tracked vehicle because of their greater simplicity.
For a mechanical engineer interested in designing a complex mechanism
to learn about statics, dynamics, strength of materials, actuators, kinematics,
and control systems, a walking robot is an excellent tool.