QFT-based design of force and contact transition controllers for a flexible link manipulator

This paper deals with the modeling, system identification and robust control of flexible link manipulators that are required to perform contact task operations. For a single flexible link (SFL) manipulator in contact, two infinite dimensional models are developed and dynamic differences with respect to the force sensing devices are examined. Generalized orthonormal basis functions (GOBFs) are adopted for system identification and new algorithms are developed that improve the identification of resonant systems. The identification results, combined with estimated measures of model uncertainties, are directly used in the design of robust controllers. For the contact transition control, a switching condition is proposed based on robust position and force controllers. The stability of the switching controller is examined using a piecewise quadratic Lyapunov approach. Both simulation and experimental results are presented showing the effectiveness of the proposed technique.