Orbital stabilization of a class of underactuated mechanical systems

Typically, the aim of a controller is to stabilize an equilibrium or a reference trajectory. For underactuated mechanical systems this objective might not be achievable because of the occurance of limit cycles due to discontinuous effects like actuator backlash or Coulomb friction. Therefore, an alternative approach is to explicitly impose a stable periodic orbit on the system by a suited controller. This way at least amplitude, frequency and settling time can be influenced directly. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)