Integrated Control For Disturbance-free Payload And Satellite Platform

As the future space missions is becoming more and more complex, the high accurancy and stability of satellit attitude control is becoming more and more important. Using appropriate satellite vibration isolation technology to weaken vibration is the key to improving the precision of satellite attitude control. Disturbance-free Payload satellite structure contains the payload module and the platform. The two modules are connected by the non-contact magnetic actuators. The structure of a satellite with Disturbance-free Payload(DFP)architecture can isolate satellite payloads from virbration sources in the physical structure, which can guarantee the precision and stability of the payload attitude. At present, the research of DFP satellite which is mainly focused on mathematical modeling, vibration isolation performance verification and structure design has gained considerable achievements. Meanwhile, designing controllers with good performance combined with the practical engineering problems is of great significance for the realization of the high precision attitude control of the DFP satellite. The content of this paper comes from a project “Dynamic Isolation Type Super High Pointing Accuracy, Super High Stability of Satellite Control Technology Research and Simulation Software Development”. Considering engineering practical problems such as the DFP satellite structure character, actuators output limited, environmental disturbnace and so on, this paper designs integrated control method for DFP satellite to achieve high precision high stable attitude control for payload module while avoiding the collision. The main contents of this dissertation are as follows:Firstly, establish mathematical model for disturbance-free payload and satellite platform. Analysis the work pattern and control system of DFP satellite, on the basis of summarizing the characteristics of DFP satellite and control system, present the kinematics and dynamics models. The relative position and attitude calculation method of the two modules are introduced in detail.Then, design attitude controlers for payload moduel and platform respectively according to attitude control problems and their different control demands and the structure features. For payload module, considering the influence of environmental disturbance, uncertainty of moment of inertia, and actuators output limited, propose a saturate nonlinear attitude control menthod without moment of inertia. For the platform, based on classical control theory and frequency domain method, design filter and PD controller to track payload moduel and suppress the chattering phenomenon of flexible appendagesLater, two kinds of relative position controllers are proposed. Making full use of the clearance between the yoke and coil of non-contact magnetometric actutors, considering the relative motion of the coil and the yoke, design the discrete logic position controller to avoid collision of the two modules and reduce the times of control. In order to further improve the safety, considering the two modules are in the conditon of environmental disturbance and limited output capacity of the actuators, design L2 gain disturbance suppress continuous controller, and theoretically proved that the control system is stable.Finally, the six degrees of freedom simulation combined with the attitude controllers is involved to illustrate the effectiveness and feasibility using the proposed control methods. The results show that high precision and high stability of integrated control for disturbance-free payload and satellite platform can be achieved.