S. Ostrovskaya, A. Kecskeméthy (U. of Duisburg), J. Angeles Nonholonomic mechanical systems pose a challenge to roboticists. Indeed, different from holonomic systems, a paradigm of which is the standard industrial manipulator, their nonholonomic counterparts require, for the description of their configurations, a number of variables greater than their degree of freedom. As a consequence, some of the state variables of these systems are neither controllable nor observable. This kind of systems is studied here with the purpose of devising novel mechanical designs and control strategies that will make the operation of rolling robots more reliable and efficient. In the process of this study, we came up with a new class of nonholonomic mechanical systems that lead to mathematical models resembling holonomic systems because of their simplicity. We term these systems quasiholonomic. Currently we are investigating mechanical design criteria under which a given robotic topology can lead to a quasiholonomic system.