Page 250 - Handbook of Biomechatronics

246 Georgios A. Bertos and Evangelos G. Papadopoulos

3.4 Right Shock Absorption
As mentioned in Hansen and Starker (2017), a big aspect of human walking
and therefore, of prosthetic walking is shock absorption. Not having the
right shock absorption can cause increased forces due to shock at the hips
and spine, which prevents the amputee from achieving high walking speeds.
Shock absorption has not been solved as a problem in prosthetic walking
(only empirical shock absorber components exist) and the scientific commu-
nity should pay more attention on resolving it. There have been honest pro-
gresses as noted in Section 4. Furthermore, prosthetic shock absorption is
even more important in other tasks such as hopping and running.

4 WALKING THEORY

Perry (1992) stated that walking is “controlled falling.” Before him,
Margaria (1976) said that walking is like an egg rolling end over end
(Fig. 1). Saunders et al. (1953) first introduced the compass-gait model
(Fig. 2A). Mochon and McMahon (1980) introduced the ballistic walking
model, which consists of two stance-phase inverted pendulum legs. Differ-
ent variations of the model include stance knee flexion, plantar flexion of the
stance ankle, and pelvic tilt. Tad McGeer added rockers to the basic
compass-gait model and built walking machines that can walk down slight
inclines under only the influence of gravity (McGeer, 1990). Coleman and
Ruina (1998), Garcia et al. (1998), and Kuo (1999) have also shown that
walking can be modeled as an inverted pendulum with rockers.
Alexander (1992) added springs to the basic ballistic model.

Fig. 1 Simple mechanical analogies of walking. (A) Stroboscopic picture of an egg
rolling end-over-end on a horizontal surface as a model for walking. (B) Stroboscopic
picture of an elastic ball bouncing on a hard horizontal surface as a model for running.
(From Margaria, R., 1976. Biomechanics and energetics of muscular excercise. Oxford Uni-
versity Press. By permission of Oxford University Press.)