Abstract: A compensation system for a spiral spring hysteresis selectively provides a reactive compressive force to the spring after retractive movement of the outermost spring end relative to a fixed axial center of the spring. Such reactive compressive force reflects what, otherwise, would be the difference between the reactive forces of extension and retraction of the spring and along an axis of greatest transmissibility of force to the spring. The spring constants of extension and retraction of the spring are resultingly compensated.

Abstract: A system for measuring coordinates of a vector in x,y,z Cartesian space includes a flexible non-elastic string spirally mounted upon a selectably positively and negatively rotatably tensioned drum, the drum having an axle of rotation and being positively rotatable as a function of positive increments of length of the string. Mounted co-integrally with the drum axle is a translational measurement encoder for converting rotation of the drum axle into a signal output corresponding to positive increments of extension of length of the string. Further provided is an assembly for defining an origin of the vector to be measured, the assembly including an origin member having an aperture therein for slidable accommodation of the string.