Page 268 - Handbook of Biomechatronics

262 Georgios A. Bertos and Evangelos G. Papadopoulos

Another new pylon is the Endolite TTPRO (Telescopic-Torsion) Pylon
(Fig. 14). Perhaps this design is superior to the other pylons because it utilizes
helical springs, instead of the elastomer ones used by the Ohio Willow
Wood Stratus or the air springs in the Seattle AirStance. In addition, the
Endolite unit is considerably less expensive than the Flex Foot’s Re-Flex
VSP. We suspect that the Endolite unit has properties similar to the
Re-Flex VSP. The TTPRO pylon primarily behaves as a spring, with very
little damping, so shock forces at heel contact during gait are attenuated.
Because damping is small, the energy associated with this attenuation is
not lost but is stored in the mechanism.
The Ohio Willow’s Pathfinder (Fig. 15) is a foot system that integrates
both a polycentric ankle and a shock absorber. The design incorporates a
lightweight, adjustable pneumatic heel spring in parallel with the toe springs
rather than in series as with most shock absorber systems. Therefore, “the

Fig. 14 TTPRO shock absorber from Endolite. (From https://www.endolite.com/prod
ucts/ttpro.)