The Tactile Exploration of a Harsh Environment by a Manipulator With Joint Backlash

Abstract

Here the tactile exploration by an autonomous robot when its joints are corrupted by significant backlash is studied. The motivation is the exploration of junctions in oil wells where the harsh conditions dictate the use of tactile exploration. These conditions also result in large, unknown, and variable backlash in the manipulator’s transmissions. Here, a method is developed to simultaneously identify the backlash and map the unknown surface. The method only needs joint encoders, and avoids the use of delicate force or tactile sensors. The mapped surface is described as a combination of geometric primitives. The robot probes the surface in several locations with its tip and computes the contact point through direct kinematics. These contact points are used simultaneously to construct a map of the environment and to identify its joint backlash, improving the precision of the map. The effectiveness of the approach is demonstrated in both simulation case studies and laboratory experiments.