Attitude control law design for moving mass control reentry vehicle based on sliding mode
Due to issues of aerodynamic ablation, complicated mechanical environment and serious nonlinear dynamics, the control system is difficult to achieve high accuracy. For nonlinear dynamics of moving mass control reentry vehicle, a design method based on sliding mode for pitch-yaw channel attitude control is proposed, which improves control accuracy and anti-disturbance capability. According to a reentry vehicle attitude control system, the pitch-yaw channel dynamic model of the nonlinear system is firstly given. Secondly, designed by using backstepping theory, a sliding mode controller with approach law is proposed. Besides, in order to reduce chattering of sliding mode control, an improved sliding mode controller is presented, in which relay characteristics is replaced with continuous functions. Finally, simulation results demonstrate the validity and feasibility.
Attitude control law for reentry vehicle based on extended state observer
In this paper, an attitude control method based on Extended State Observer (ESO) is developed. The proposed scheme allows for uncertain influences in the system, such as the aerodynamic cross coupling, inertial coupling between each channel in the attitude motion and model parameter uncertainties. In order to decrease the influences, this method uses an ESO to estimate the total influence of various disturbance factors. The simulation result shows that the proposed controller based on ESO can suppress the influence of channel coupling effectively. The control precision is greatly improved compared with the traditional method.
Software Tools for Nonlinear Missile Autopilot Design
A computer-aided design software package for nonlinear control synthesis is discussed. The software incorporates five different modern nonlinear control methods. The versatility of the software lies in its ability to develop nonlinear controllers using a simulation model. As a result, models of arbitrary complexity can be used in the control law development. The use of the design software is illustrated through the design of nonlinear regulators for a longitudinal missile model.