Direct and indirect adaptive control of a two-mass drive system — a comparison

The paper deals with the application of two adaptive control structures for the speed control of the drive system with elastic joint. The first one is based on the direct adaptive control schemes and the model reference adaptive control system (MRAS) is used. As a speed controller, the neuro-fuzzy sliding mode controller (NFSC) is utilized. The torsional vibrations are successfully suppressed in the control structure with only one basic feedback from the motor speed. The damping ability of the proposed system has been confirmed for a wide range of system parameters. The second control structure is based on the indirect adaptive control scheme. As an identification tool, the extended nonlinear Kalman filter (ENKF) which estimates the non-measurable states and the parameters (time constant of the load machine) of the system is used. The information of the estimated parameter is used to retune on-line the control structure coefficients. To improve the performance of the ENKF the additional algorithm, which is changing, the covariance matrix Q is applied. The simulation results are confirmed by laboratory experiments.