Adaptive control of the electrical drives with the elastic coupling using Kalman filter

The control problem of the two-mass system originally derives from rolling-mill drives (Sugiura & Hori, 1996), (Ji & Sul, 1995), (Szabat & Orlowska-Kowalska, 2007). Large inertias of the motor, rolls and long shaft create an elastic system. The motor speed is different from the load side and the shaft undergoes large torsional torque. A similar problem exists in the field of conveyer drives (Hace et al., 2005). Also the performance of the machines used in textile industry is reduced by the non-ideal characteristics of the shaft (Beineke et al., 1997), (Wertz et al., 1999). An analogous problem appears in the paper machine sections (Valenzuela et al., 2005) and in modern servo-drives (Vukosovic & Stojic, 1998), (O’Sullivan et al., 2007), (Shen & Tsai, 2006). Moreover, torsional vibrations decrease the performance of the robot arms (Ferretti et al., 2004), (Huang & Chen, 2004). This problem is especially important in the field of space robot manipulators. Due to the cost of transport, the total weight of the machine must be drastically reduced. This reduces the stiffness of the mechanical connections which in turn influences the performance of the manipulator in a negative way (Katsura & Ohnishi, 2005), (Ferretti et al., 2005). The elasticity of the shaft worsens the performance of the position control of deep-space antenna drives (Gawronski et al., 1995). Vibrations affect the dynamic characteristics of computer hard disc drives (Ohno & Hara, 2006) and (Horwitz et al., 2007). Torsional vibrations can appear in a drive system due to the following reasons: changeability of the reference speed; changeability of the load torque; fluctuation of the electromagnetic torque; limitation of the electromagnetic torque; mechanical misalignment between the electrical motor and load machine; variations of load inertia unbalance of the mechanical masses; system nonlinearities, such as friction torque and backlash. The simplest method to eliminate the oscillation problem (occurring while the reference speed changes) is a slow change of the reference velocity. Nevertheless, it causes the decrease of the drive system dynamics and does not protect it against oscillations appearing when the disturbance torque changes. The conventional control structure based on the PI