Hart's A-frame walker
Hart's A-frame linkage biped application. Exact straight line. big stride.
■ Variation Chebyshev linkage's bar ratio is fixed. But, above Hart's A-frame ratio is more variable. ex. Very long stride leg is easy. Bar length calcuration is easy. if you want height = h, stride = x, ----- other bars are function(h, x) i.e. BH=h, OL=LD=0.5 x, so, then if OE'=y, E'B=z, solve next eq. ① & ②. when ∠OLD = 180° then ∠OE'B = 180° (y+z)2 = x2 + h2 ---- ① and, when ∠OLD = 0° then ∠OE'B = 0° so, z-y = h ---- ② (As a matter of fact, yz = x2 is true, too. ∠OLD = ∠OE'B is always true.) ① is (h+2y)2 = x2 + h2 -----→ y is given.