Robust sliding mode - based interval Type-2 fuzzy logic observer for quadcopter UAVs

The availability of information on all states plays a critical role in a wide range of fields including quadcopter UAVs. Sensor limitation, accuracy, noise, and uncertainty are issues that limit acquisition of information on states of such vehicles. Sliding mode observer (SMO), as a nonlinear observer, is believed to be able to deal with such issues. However, the chattering phenomenon in SMO is still an issue that may lead to performance degradation. Interval Type-2 fuzzy logic system (IT2FLS), which has the capability to accommodate uncertainties of the system, will play a vital role in eliminating this phenomenon. A hybrid mechanism by combining the two methods is investigated in this paper. The proposed method is compared with Type-1 fuzzy logic observer to show the advantages of the approach. The results obtained demonstrate good performance of the approach in dealing with noise and uncertainty as well as eliminating the chattering phenomenon of SMO.