This study considers the current tracking control of the LCL-type grid-connected inverters by using a fully actuated system (FAS) approach. To tackle this problem, a FAS approach-based predictive proportional-integral (PI) control is constructed with simple design and better performance. Firstly, an equivalent transformation is presented to convert the model of the LCL-type grid-connected inverters and its general form into the input-delay FASs, so that the proposed work can be regarded as the tracking control of the input-delay FASs. Secondly, a predictive PI control is developed by means of the FAS approach to realize the desired tracking control for eliminating the original nonlinearities and compensating for the input delays. Then, a sufficient criterion is proposed for the bounded stability and tracking performance of the closed-loop systems. Finally, a compared simulation is shown to demonstrate the feasibility.

An adaptive prescribed performance controller based on the fully actuated system approach is designed for the position and attitude control of the combined spacecraft formed after the successful capture of the non-cooperative spacecraft, considering the influence of unknown disturbance in the combined spacecraft system. A combined spacecraft position and attitude dynamics equation is established based on the Euler's attitude dynamics equation and the orbit dynamics model. The transient and steady-state performance of the combined spacecraft position and attitude error is constrained by introducing a prescribed performance function. Furthermore, the adaptive prescribed performance controller is designed for the combined spacecraft state error system with unknown disturbance by applying the fully actuated system approach. In addition, the proposed adaptive prescribed performance controller is proved by constructing the Lyapunov function. Finally, the numerical simulation results based on the combined spacecraft system model and the experimental results obtained from the semi-physical simulation platform show that under the action of the designed controller, the combined spacecraft can achieve accurate position and attitude control and the state error of the system is always within the prescribed performance envelope, which verifies the effectiveness and practicality of the designed controller.

A High-Order Fully Actuated (HOFA) predictive control approach is proposed for the problem of spacecraft flying-around under time-variant communication constraints in a sight coordinate system, including both time-variant communication delays and time-variant packets dropouts in the communication channels between the servicing spacecraft and the tracking and data relay satellite system. In the sight coordinate system, a nonlinear HOFA system model is introduced to describe the relative dynamics of spacecraft flying-around, such that the proposed flying-around task can be considered as a tracking control problem of nonlinear HOFA system. In this approach, the nonlinearities can be eliminated to construct a linear HOFA system because of full actuation characteristic, and then a Linear Incremental HOFA (LIHOFA) prediction model is constructed by applying a Diophantine Equation to replace a reduced-order prediction model, such that multi-step ahead predictions are developed to achieve the optimization of tracking control performance and the compensation of time-variant communication constraints, which guarantees the realization of this flying-around mission. A necessary and sufficient condition is given to analyze the stability and tracking performance of closed-loop system. Further, two simulated examples of spacecraft flying-around in circular and elliptical orbits are provided to verify the feasibility of HOFA predictive control approach.