Fig. 5.
Mapping from spring resting lengths (si) to hand positions (x, y). Several redundant resting lengths are solutions for one desired hand position (red). The graph on the left shows a two-dimensional projection of a cross section of the six-dimensional nullspace of spring resting lengths: s1 and s2 were set to constant values; s3 and s4 were randomly drawn (within dashed box), and all values of s5 and s6 were projected onto the displayed plane. The original six-dimensional nullspace in rest-length space is, therefore, nonconvex. Thus, the average of all rest-lengths solutions does not map onto the desired hand position.