A helicopter pitch angle stability control method using a second-order sliding mode

Abstract

This invention constructs a sliding mode surface by superimposing the pitch angle error signal, the pitch rate signal, and the nonlinear piecewise integral signal of the error. A second-order nonlinear error coupling filter is then designed to obtain the first-order and second-order output signals of the sliding mode filter. These are then superimposed through error coupling to obtain a hybrid differential signal of the second-order sliding mode surface. By superimposing equivalent control terms and adaptive disturbance estimation terms, the desired value of the main motor armature voltage is calculated using second-order sliding mode control. Then, using an inversion design approach, the desired armature voltage rate signal is gradually obtained by integrating the piecewise coupled pitch angle error signal. Finally, the helicopter pitch control signal is obtained through equivalent voltage and error feedback and inversion calculation, and then sent to the main motor, thus realizing attitude tracking control of the helicopter pitch channel.

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