Finite-time Event-triggered Attitude Tracking Control For Spacecraft Based On Fuzzy Observer

Attitude tracking control is the basis for a spacecraft to complete complex and diverse aerial tasks,and it has been a key research topic.The high requirements for spacecraft control objectives and performance indicators make the spacecraft attitude tracking control more practical,but the nonlinear nature of the spacecraft attitude model itself makes it difficult to study the tracking control problem.In order to further improve the control performance of the spacecraft based on the existing research results,the following aspects of the spacecraft attitude tracking control problems with full state feedback and unknown state feedback are investigated.A fast finite-time event-triggered attitude tracking controller is designed to solve the problems of slow convergence of system states and high computational resource consumption,which have been neglected in most studies.Based on the spacecraft attitude model described by quaternions,the real-time optimal angular velocity is designed according to the optimal control law,and the event-triggered mechanism is used to reduce the input signal update frequency to reduce the resource consumption,and the fast finite-time control method is applied to achieve the system stabilization quickly.The Lyapunov stability of the system is verified,and the Zeno phenomenon is excluded.The simulation results show that the system achieves fast and finite-time stability,and the event-triggered mechanism does not affect the accuracy and speed of the system output signal,and also reduces the number of passes between the controller and the actuator,freeing up more computational and communication resources,which verifies the fast and effective method.Considering that in the actual control of spacecraft attitude,the state like angular velocity is not measurable due to unpredictable reasons.A finite-time event-triggered controller based on fuzzy observer is designed to achieve the tracking control of attitude with unknown angular velocity.To avoid parameter redundancy,a modified Rodrigues parameters describe the spacecraft attitude model,a fuzzy observer estimates the unknown state,fuzzy logic system approximates the unknown nonlinear function,an event-triggered mechanism still reduces the update frequency of the input signal,and the actual finite-time control method is applied to achieve system stability.The finite-time stability of the system is verified by Lyapunov stability theorem,and the Zeno phenomenon is excluded.The simulation results show that the system achieves actual finite-time stability,the fuzzy observer successfully performs state feedback,and the event-triggered mechanism for different actuator designs with different thresholds well balances the communication limits and tracking performance,reduces the communication burden,and verifies the effectiveness of the method.