Finite-time Attitude Tracking And Cooperative Control Based On Spacecraf

For the spacecraft system with external disturbance,inertial matrix uncertainty and network attack,the problem of finite-time attitude tracking and cooperative control is studied by using the sliding mode control technology,prescribed performance control method,back-stepping method,reinforcement-learning technique and mode-free adaptive control method.By using the Lyapunov stability theorem and numerical simulation,the effectiveness of the control algorithm is verified.The research content of this paper includes three parts as follows:(1)For the single spacecraft system with external disturbance and inertia matrix uncertainty,a finite-time attitude tracking control scheme is proposed by using the prescribed performance control method.Firstly,a novel finite-time performance function is used,which can avoid the complicated calculation of a traditional exponential performance function.Then,an error transform is introduced to ensure that a constrained problem is transformed into an unconstrained problem.Then,a robust adaptive control algorithm is proposed by using the back-stepping method and terminal sliding mode control technology.Different from the existing attitude tracking control results,the proposed control scheme can guarantee the tracking performance of the spacecraft system in both a steady state and a transient state.In addition,the state trajectories of spacecraft systems can be completely drawn to the designed sliding surface.Simulation results confirm the finite-time attitude tracking control of the single spacecraft system.(2)For the multiple spacecraft systems with external disturbance and inertia matrix uncertainty,a fixed-time attitude cooperative control scheme is proposed by using the state observer and sliding mode control technology.Firstly,a fixed-time adaptive state observer is proposed to estimate the state of the leader.Then,in order to integrate the unknown nonlinear terms of the spacecraft system,a dynamic equation based on observation error is proposed.Then,by using the reinforcement-learning technology of the critic-actor neural-network framework,a robust sliding mode control algorithm based on a neural network is proposed to achieve optimal fixed-time attitude cooperative control.Different from the existing attitude cooperative control results,the proposed control scheme realizes the coupling design of observer and controller.In addition,the global information of network communication topology is not required in the design of the controller.Simulation results confirm the fixed-time attitude cooperative control of the multiple spacecraft systems.(3)For the single spacecraft system and the multiple spacecraft system under network attack,a data-driven finite-time control scheme is proposed.Firstly,the nonlinear spacecraft system is transformed into a linear system by using the dynamic linearization method.Secondly,the constrained problem is transformed into an unconstrained problem by introducing a finite-time performance function and output transformation.At the same time,an attack compensation scheme is designed to eliminate the influence of network attack.Based on the prescribed performance control method and the attack compensation scheme,a finite-time model-free adaptive control algorithm is presented to realize attitude tracking and cooperative control within a finite time.Different from the control results of the above two parts,the information of the system model is not required in the proposed control scheme.Simulation results confirm the finite-time attitude tracking and cooperative control of spacecraft systems.