Abstract:This article takes a certain type of unmanned tandem rotor helicopter as the research object, designs and improves its inner loop attitude control law. In response to the problems of strong coupling, high nonlinearity, low yaw efficiency, and significant external interference in the flight process of the tandem rotor helicopter, a non-singular terminal sliding mode control strategy is adopted, combined with an improved double power approaching law, to achieve high-precision control of the flight attitude. In addition, in order to further enhance the anti-interference ability of the control system, an extended state observer was designed to effectively suppress external disturbances. The simulation results show that the attitude control law designed in this paper significantly improves the dynamic response characteristics, disturbance rejection performance, and robustness of the control system, and greatly enhances the system's ability to suppress sliding mode chattering.