THE CONTROL OF QUADCOPTERS BASED ON THE FEEDBACK LINEARIZATION METHOD

Abstract

Some essential dynamic and structural features of quadcopters’ control systems with the feedback linearization are discussed. The feedback linearization of nonlinear dynamics of the quadcopters is extensively used in the development of adaptive control, predictive control, fault-tolerant control in case of the motors’ efficiency degradation, etc. It is shown that using the feedback linearization with the proper choice of a matrix regulator in the direct channels of the nonlinear multi-input multi-output control system results, if there are no motor degradations, in complete compensation of kinematic and dynamic cross-couplings between separate channels. This reduces the design of the quadcopter control system to the design of four independent single-input single-output channels, namely, the altitude, roll, pitch, and yaw channels, on the basis of classical feedback control. In case of motors efficiency degradation, the quadcopter dynamics are described by a system of cross-coupled nonlinear equations. This imposes certain severe constraints on the design techniques that are based, for example, on application of the Model Reference Adaptive Control (MRAC) in combination with the feedback linearization to fault-tolerant control systems for quadcopters. The same refers to any design methodology that makes use of the Lyapunov’s second method on an assumption that the nonlinear system with the feedback linearization can be represented, roughly speaking, as a serial connection of some “linear” and “nonlinear” parts.