Experiments in Impulsive Manipulation

In this paper, we present the results of our experimental effort in one form of impulsive manipulation: tapping. Our previous work studied the mechanics of tapping a planar object which then slides on a support surface, coming to rest due to friction. This work addresses the practical issues in creating a system which uses this mode of manipulation. We begin with the design of tapping devices—end effectors designed to deliver an impulse to an object, and report some of the issues we have found to be important in their design. Our next step was to perform single-tap experiments in order to fit and evaluate the models of impact and sliding. These experiments have shown that objects rotate less than predicted; we have found that the addition of a scaling factor for the torque due to friction enables the models to predict object motion reasonably well. In order to do positioning experiments, we developed a number of planning methods (or feedback control strategies) to compensate for errors in modeling, parameters, and actuation. These planning methods were successfully used to demonstrate a positioning task. We also have experimentally demonstrated that tapping can be used to position an object more precisely than the manipulator can position the tapping device. We offer some sensitivity analysis in support of this result.