“…Most of the authors considered the main source of errors to be only geometric, with the exception of (Chen at al., 1987) and Whitney et al (Whitney et al, 1986), who included explicitly non-geometric errors as well. Although some introduced their own models (Whitney et al, 1986), the majority used models that are universally valid and widely accepted, such as the Denavit-Hartenberg or modified versions of it ((Khalil et al, 1991), (Driels, 1993) and (Harb & Burdekin, 1994)). Much previous work is based only on computer simulations, but some validation work used real measurements ( (Chen at al., 1987), (Whitney et al, 1986), (Stone, 1987) (Stanton & Parker, 1992) (Khalil et al, 1991), (Driels, 1993), (Driels & Pathre, 1994) and (Abderrahim & Whittaker, 2000)), and very recently there is even commercial application dedicated to robot calibration ((Renders, 2006) and (Fixel, 2006)).…”