Moment Of Inertia Identification Of Served Spacecraft Based On Cellular Satellite

For the expensive instruments and equipment carried by some large spacecraft,when the large spacecraft fails,the load will lose its function,causing serious waste.At present,the use of standardized and modular cell satellites to provide in orbit service for the spacecraft has received widespread attention from all over the world.For most of the on orbit maintenance services of cell satellite,when it is attached to the surface of spacecraft,the primary task is to replace its failed attitude control system and take over the attitude control of spacecraft,so as to realize the reuse of the important payload of the failed spacecraft.Due to the cell maintenance attached to the spacecraft surface,the moment of inertia of the combined spacecraft changes.For some attitude control,accurate moment of inertia parameters of the combined spacecraft are needed.The main research content of this thesis is to use the cell satellite to excite the combined spacecraft,and use the corresponding data to identify the moment of inertia of the combined spacecraft,so as to obtain the precise moment of inertia parameters of the spacecraft.In this thesis,firstly,recursive least square algorithm is used.At the same time,in order to avoid the limitation of computing and communication ability of cellular satellite,a distributed topology is used to identify the rotation of the combined spacecraft in an open loop.At the same time,because the required angular acceleration information can not be directly measured,and the cell satellite can not obtain the overall external torque,a linear angular acceleration observer and a torque estimator are designed for each cell satellite to obtain enough information,and then the moment of inertia identification of the combined spacecraft is realized.Then,in order to solve the problem that the attitude of the combined spacecraft can not be controlled by the open-loop identification,an adaptive law about the moment of inertia of the spacecraft is designed by using CL algorithm.Under the condition of direct external excitation,similar to the recursive least square algo rithm,the moment of inertia parameters of the combined spacecraft are identified and the open-loop identification is realized.In addition,in order to control the attitude of the spacecraft,the backstepping method and the corresponding moment of inertia adaptive law are adopted to design the corresponding control torque.The attitude control of the combined spacecraft is completed while the moment of inertia parameters are identified.When cell satellites are used to control the combined spacecraft,the control torque of a certain number of cell satellites is limited due to the limitation of their volume and mass.Therefore,it is an important practical problem to consider the torque input saturation.In order to solve the problem of torque input saturati on of cellular satellite,the sliding mode control theory is combined with the above CL algorithm,and through the design of control law,the control torque of attitude control of combined spacecraft is changed in a certain range,so as to complete the attitude control and moment of inertia parameter identification of combined spacecraft under the constraint of torque input saturation.