Dynamic analysis and coupling control of underactuated flight vehicles with single moving mass

Abstract

Three-channel attitude motion of an underactuated flight vehicle with laterally configured single moving mass is investigated. Of particular interest are three interrelated issues, first, the discussion of longitudinal static stability and trim angle-of-attack considering the lack of active control input in the pitch channel, second, the problem of channel cross coupling and moving mass inertial coupling, third, the coupling control using the single moving mass offset to achieve command roll angle tracking and side slip angle stabilization for the underactuated system. Nonlinear dynamic analysis indicates that the longitudinal static stability and the trim angle-of-attack are determined by the installation position and the mass ratio of the moving mass, interestingly, installing the moving mass at the center-of-mass of the vehicle body not only makes the trim angle-of-attack insensitive to flight conditions and the mass ratio, but also can ensure the longitudinal static stability over a large range of the mass ratios. Moreover, analysis of three-channel coupling dynamics reveals that the entire system may experience oscillation even divergence when initial disturbance of side slip angle and frequent offset of the moving mass exist. Therefore, an improved underactuated active disturbance rejection controller is proposed to deal with the roll-yaw coupling control problem, and the stability of which is analyzed, additionally, the multiple controller parameters are optimized based on the particle swarm optimization algorithm. Closed-loop simulation results in different cases prove the effectiveness and robustness of the designed controller. The proposed control scheme sufficiently utilizes the control capability of the single moving mass to enhance the anti-disturbance ability of the flight vehicle system, which permits the economic benefits and application prospects.