| Abstract |
In a position-controlled, electrically driven, elastic two-mass system severe stationary and dynamic disturbances are observed due to backlash or Coulomb friction, as for example chattering and stick-slip motions. The decisive parameters to produce these stable limit cycles are found with the Harmonic Balance, using describing functions, and with the circle criterion. By introducing a first-order observer small and big limit cycles are avoided completely in the system with backlash as well as high-frequency stick-slip motions are in the system with Coulomb friction. The tendency to low-frequency stick-slip is reduced significantly. Moreover, this observer improves the disturbance performance of the linear system considerably and allows simple cascade control to be applied down to low eigenfrequencies. |
