Exploration and dynamic shape estimation by a robotic probe

A strategy for motion of a planar manipulator on an unknown surface is presented. To estimate a parameter vector for the surface, least-squares estimators are formulated that use both the kinematic and dynamic data available online. The authors begin with the presentation of a control strategy that uses local sensory data to guide the end effector incrementally over the surface. Force feedback is given, which is later shown to be successful in the uninterrupted maintenance of contact. Motion over the unknown shape is justified by demonstrating that a simple shape estimation algorithm can converge to give a parametric description of the surface. Geometric and differential models of the surface are presented and the estimation procedure is specified. Also presented are the results of a number of computer simulations for a three-link planar manipulator moving over an ellipse whose parameters are unknown to the controller. It is found that, in the presence of noise, dynamic data degrade the estimates.<>