Backlash compensation for motion system with elastic transmission

Abstract

Control of mechanical system with backlash is a topic well studied by many control practitioners. This interest has been motivated by the fact that backlash is one of the most important nonlinearities, that primary limit the performance of speed and position loop in industrial motion system, such as robotics, automation and many other motion systems. This research deals with backlash in two-mass system, which well represents the majority of such systems. In this research backlash is treated as torque disturbance, which enter the system at the location of the backlash. Then a disturbance observer (DOB) is constructed in order to estimate and compensate the disturbance in an inner feedback loop fusion, such that the outer controller will used to control “backlash-free” system. Also the issue of torsional vibrations is investigated. Such vibrations are often generated because of the elastic shaft connected between the two masses (usually motor and load inertias). The torsional torque disturbance is estimated and compensated by using the disturbance observer in the same manner as the backlash.