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.
Creating the Virtual Universe
Simulation software is important to our understanding of the universe. The intrinsic multiphysics aspects are spiced with a range of temporal scales and spatial scales, both of which cover more digits than are available in the standard hardware. This, together with the intrinsic chaotic nature of many physical processes, poses quite a challenge. To meet this challenge, researchers developed the Astronomical Multipurpose Environment (AMUSE). Instead of writing a suite of multiphysics solvers from scratch, AMUSE's developers coupled existing solvers for each physical ingredient. The result is a highly inhomogeneous collection of dedicated solvers with a homogeneous protocol that scales to supercomputers.