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The DLR light-weight robots (LWR) have been developed forapplication areas which are fundamentally different from theones of classical industrial robotics. The strengths ofindustrial robots are especially high positioning accuracy(repeatability and absolute accuracy), high speed, durability,and robustness, as well as the relatively low price. Therefore,today’s industrial robots are used especially in well structuredenvironments, in which the position and shape of the parts tobe manipulated are well determined and in which collisionswith the environment and humans can be estimated andexcluded in advance. High performance is achieved for fasttasks which are repeated numerous times. Generally, the highpositioning accuracy requires high stiffness at the price of highrobot mass relative to its payload.In contrast, the robotic systems developed at DLR (arms,hands, a humanoid manipulator) are designed for interactionwith humans in unstructured, everyday environments. In suchapplications, high absolute positioning accuracy cannot beexploited due to limited accuracy of position informationabout the surrounding environment, while its side-effects indesign (high stiffness and mass) are clearly undesired. TheDLR robots (Figure 1) are thus designed for application areaswhich are generally not covered by industrial robots, but arestill ongoing research topics. Typical examples are:. assembly processes for which the position estimation forthe mating parts and/or the positioning accuracy of therobot is significantly below the assembly tolerance;. applications in which the robot works in immediatevicinity of humans and possibly in direct physicalcooperation with them; and. mobile service robotics applications (arms mounted onmobile platforms), for which the information about theposition of the robot and the surrounding objects, as wellas about the dimension of these objects is afflicted withrelatively high uncertainty.