Feedback control methods for distributed manipulation systems that involve mechanical contacts

In this paper we introduce feedback control methods,for distributed manipulation systems that move objects via rolling and slipping point contacts. Because of the intermittent nature of these mechanical contacts, the governing mechanics of these systems are inherently non-smooth. We first present a methodology to model these non-smooth mechanical effects in a manner that is tractable for non-smooth control analysis. Using these models, we show that when considerations of these non-smooth effects are taken into account, a class of traditional open-loop distributed manipulation control methods cannot stabilize objects near an equilibrium. However, stability can be achieved through the use of feedback, and we present non-smooth feedback laws with guaranteed stability properties. We then describe an experimentol modular distributed manipulation test-bed upon which one can implement a variety of controlschemes. Experiments with this test-bed confirm the validity of our control algorithms. Multimedia extensions include videos of these experiments.