Research On Orbit Planning And Attitude Control Of Reentry Vehicles With Compound Actuators

The hypersonic reentry vehicle has the characteristics of fast response and global accessibility,which is of great significance in both military and civil fields.The maneuvering capability of a single hypersonic reentry vehicle is limited and the global arrival has to be realized through a constelltation of in-orbit vehicles.Thus it is necessary to study the orbit planning method.In the key technologies of hypersonic reentry vehicle,attitude control is very important.The control moment gyroscope,as a new type of reentry attitude actuator,will have broad prospect of application.The research object of this dissertation is focused on the hypersonic reentry vehicle.Its in-orbit orbit planning method and the attitude control method during the deorbit and reentry phases based on the control moment gyro and the reaction control system are studied.Furthermore,the hardware-in-the-loop simulation experiments are carried out.The main research results are as follows:A constellation orbit planning method for responsive global reach based on the technique of splicing the reachable domain belts generated by orbital maneuvers is proposed.A new concept of generating terrestrial reachable domain by making use of the shift of ground tracks due to the orbital maneuvers is proposed.The differences between the traditional coverage and the proposed reachable domain generated by the orbital maneuver are analyzed.The reachable domain belts of a single in-orbit vehicle in the equator are solved in the presence of J₂ perturbation,for the two-and one-impluse cases,respectively.The relationships between the maximum reachable domain belt in the equator and the available velocity increment,the initial orbital altitude,and the response time are analyzed.An analytical constellation planning method which splices the maximum-width reachable domain belt uniformly in the equator is designed.Furthermore,an optimized constellation planning method,which makes use of all reachable domain belts to get an optimized splicing,is proposed.The“Genetic algorithm+Pattern search algorithm”is proposed to solve for the optimization of the planning parameters.Numerical examples demonstrate the feasibility of the proposed constellation planning methods.A nealy real-time time-optimal attitude control method based on the control moment gyros during the de-orbit phase is proposed.The time-optimal attitude maneuver problem in the deorbit phase is analyzed,the essential condition of optimality is deduced,and the conclusion that Hamilton function is equal to zero on the optimal path curve is reached,which can be used for testing whether optimum control solution meets the essential condition of optimality or not.The Gauss pseudo-spectral method is applied to solve the optimal maneuvering trajectory,and the simulation results show that the optimal maneuvering trajectory is of bang-bang type.In order to apply the pseudo-spectral method in approximately real-time control,an improved pseudo-spectral method is proposed to solve the time-optimal attitude maneuvering problem.Its fundamentals and solving method are elaborated,and the mapping relation between the costate variables and the KKT multipliers are deduced,which can be used to judge the optimality of the attitude maneuvering trajectory planning results.Simulation examples indicate that the improved pseudo-spectral method is capable of automatically judging whether switching times are correct or not,and its computation speed is an order of magnitude faster than that of Gauss pseudo-spectral method.It can also accurately get the switching time,so it has better optimality.The LQR method is adopted to design the optimal trajectory tracking controller,and the simulation examples verify that the controller has good performance,and it can be used for real-time control.A control moment gyro-and reaction control system-based reentry attitude control method is proposed.The control moment gyro-based attitude stabilization control method in the early reentry phase is analyzed and the quasi-sliding mode controller is proposed.The control moment gyro-and reaction control system-based roll channel attitude control method in the late reentry phase is proposed.The control system structure of the compound actuators are analyzed,and the roll channel control law based on sliding mode control method is designed.In addition,the fuzzy control distribution law is designed so that the control moment can be optimally distributed to the two actuators.The response speed of the control moment gyro is also analyzed,and the result shows that its response speed is in 10ms order of magnitude,so it can be used as the attitude control actuator in the late reentry phase.Response characteristics of the control moment gyro and the thrust delay of the RCS are taken into account in the simulation examples,and simulation results verify that the proposed fuzzy control distribution law is feasible,and the sliding mode control law shows good performance in the presence of external disturbance torque.A triaxial air-bearing table-based semi-physical simulation system for attitude control is established and simulation experiments are conducted.The components of the semi-physical simulation system are given,and a small 1.5Nms/0.5Nm control moment gyro prototype based on mechanical bearing is developed.In order to meet the need of real-time control,a short-delay wireless terminal is developed for real-time communications between the air-bearing table testing apparatus and the real-time target computer,and an FPGA-based communication board which can convert the multi-serial port data to the single serial port data is developed.The semi-physical simulation experiment for the roll-channel attitude control in the reentry phase is conducted,and its results show good coherence to that of numerical simulation examples,verifying the effectiveness of the control algorithm.This dissertation has conducted a thorough research on control moment gyro-and reaction control system-based hypersonic reentry vehicle trajectory planning and attitude control method from in-orbit phase,deorbit phase to reentry phase,and its research finding can provide theoretical and technological support for the R&D of future new-concept hypersonic reentry vehicle.