Adaptive feed-forward control for inertially stabilized platform

An adaptive feed-forward control method combining with feedback control was proposed to improve the command tracking performance of control circuit in an inertial stabilized platform. On the basis of subspace system identification, the input-output data were used to identify a state space of the stabilized platform model and the frequency-domain loop shaping technique was used to design the feedback loop controller to reject the external disturbance. Furthermore, a Recursive Least Square (RLS) adaptive filter was taken to build the inverse model of the feedback control loop and to construct the all-pass transfer function for increasing tracking performance. Several tracking experiments were conducted on different command inputs to verify the validity of the adaptive feed-forward controller. Experimental results show that this method responses quickly to step commands and the overshoot has decreased from 30% to 4.5% as compared with that of the feedback control. For a sinusoidal signal at the frequency of 30 Hz, the adaptive feed-forward controller can obtain an amplitude response without attenuation and the phase lag is reduced to 54° from 90° as compared with that of the feedback control. This method significantly improves the transient performance and is superior to the feedback control alone. ©, 2015, Chinese Academy of Sciences. All right reserved.