Research On A Thrust Allocation Algorithm Of Overactuated Spacecraft

The thruster plays an important role in the orbit and attitude control of a spacecraft. To make sure that the spacecraft could take a reliable operation in orbit, existing design method often adopt redundant configuration for the thruster system, one of the key issues during spacecraft control algorithm design is how to make the desired control directives assigned to the redundant thrusters whose thrusts are restricted. Control allocation method exists in the implementing agencies under the conditions of redundancy to achieve an optimal criterion or constrained optimal allocation, for the redundant thruster configuration provides a dynamic distribution channel enabling technologies. Based on this thesis, we carried out some study about the control allocation with the distribution of the spacecraft thrust, and the following innovative research results were obtained:Based on work characteristics of the thrusters, mathematical model about the integration control allocation problem is founded and a redistributed pseudoinverse algorithm which satisfies the orbital and attitude control demand were proposed. The first the pseudoinverse algorithm can compute the force and torque; and the second an redistributed algorithm is proposed by analyzing the null-space of the control effectiveness matrix, which may lead the thrusts into saturation. This method revises all the thrusts to the confine that thrusters could offer. At last taken simulation, the results validate the feasibility and effectiveness of those algorithms. The method is an algebraic solution process; it has high efficiency, suitable for application of the spacecraft on orbit.For the control of redundant thrusters which can be actuated both by the orbit control system and attitude control system, the algorithm mentioned above were taken to control the expected forces and torques. The simulation results validate the effectiveness of reducing fuel consumption. We propose a control allocation method that raised the priority of orbit control. This method allocates the expected orbit force at first, for the configuration design of redundant thrusters. There are many feasible solutions. From those feasible solutions, we find the optimal solution which is as close as possible to attitude control torque. The remaining expected torque is produced by reaction wheels. Mathematical model about orbit method of dynamic control priority is proposed to founded. And then we used linear method to solve this problem. Simulation results show that the algorithm has favorable dynamic performance and achieves its task.The lifetime of a formation flying mission not only depends on the individual spacecraft energy consumption but also on the energy consumed on each spacecraft with respect to others. To solve the problem of the balanced-energy consumption, an optimized balanced-energy algorithm, which is based on the technology of control allocation, is proposed. To solve the balanced-energy reconfiguration problem for formation flying system, we consider the Hamiltonian, and define the each thrust vector difference as an objective functional. At last 6 degree-of-freedom simulation is taken, The feasibility of control allocation applied to solve the balanced-energy control problem is further explored.