Combined Energy And Attitude Control System Research Articles

Deep learning based fuzzy-MPC controller for satellite combined energy and attitude control system

Combined Energy and Attitude Control System (CEACS) reduces the size and mass budgets of typical satellites and consequently, increases their payload capacity. CEACS uses flywheels for a dual purpose, i.e., as both energy storage and attitude control device. This maiden work attempts to introduce a novel Deep-Learning capability of the fuzzy-Model Predictive Control (FMPC) controller for CEACS. The design approach for the fuzzy-MPC controller uses the Takagi-Sugeno (T-S) fuzzy model of satellite attitudes and computes the control torque through a parallel distribution compensation (PDC) approach. However, the MPC controller offers a high computational burden, and it becomes a significant problem for smaller satellites having limited computational power. Therefore, in this research work, a novel Deep-Learning-based fuzzy-MPC controller (D-FMPC) is designed for the CEACS attitude regulation subject to higher initial angles, actuator constraints, parametric uncertainties, and external disturbance torques. Here, the deep-layer neural network is trained offline with the MPC controller data to replicate the FMPC controller, thus ensuring its controllability. Numerical results validate that the D-FMPC controller successfully mimics the FMPC controller and produces the desired pointing accuracy effectively with smooth transient response and without violating the attitude control actuator constraints. The results also validate that the D-FMPC controller offers significantly reduced computational burden than the FMPC controller. Therefore, the novel Deep-Learning solution provides a feasible platform for applying more complicated and sophisticated attitude control techniques for the CEACS attitude regulation in small satellites as an example.

Model predictive control for Takagi–Sugeno fuzzy model-based Spacecraft combined energy and attitude control system

A Combined Energy and Attitude Control System (CEACS) is a dual system in which flywheels are used as energy storage and attitude control devices. This work is a progress on CEACS for small satellites to improve the attitude accuracy. In this maiden work, the Fuzzy–MPC controller is introduced to regulate the CEACS attitude with both linear and nonlinear initial angles, and in the presence of actuator constraints. The nonlinear attitude model is transformed into a set of linear subsystems using the Takagi–Sugeno fuzzy modeling approach. The subsystem is designed with a MPC controller and a total control action is summed up using the parallel distributed compensation approach. The numerical results have been analyzed in terms of attitude pointing accuracies, actuator constraints, and energy consumed by the actuators. A performance comparison between the Fuzzy–MPC and Fuzzy–LQR controllers has also been done. The results validate that the Fuzzy-MPC controller achieves the desired CEACS attitude pointing accuracy of 0.0010° with a zero steady-state error and keeps the control torques within the actuator constraints. On the other hand, the Fuzzy–LQR controller gives some measurable steady-state error and achieves the CEACS attitude pointing accuracy of 0.0012°. Therefore, the Fuzzy–MPC based CEACS architecture not only achieves the desired pointing accuracies but also produces ten times smaller control torques than the Fuzzy–LQR controller, which result in a lower onboard power consumption.

The fuzzy PD control for combined energy and attitude control system

PurposeThe satellite pointing accuracy plays a crucial role in ensuring a successful satellite mission itself. Therefore, this paper aims to enhance the attitude pointing accuracy of the combined energy and attitude control system (CEACS) in a satellite in the presence of external disturbance torques through a robust controller, which can produce high pointing accuracies with smaller control torques.Design/methodology/approachTo improve the CEACS attitude pointing accuracy, a maiden fuzzy proportional derivative (PD)-based CEACS architecture is proposed. The mathematical models along with its numerical treatments of the fuzzy PD-based CEACS attitude control architecture are presented. In addition, a comparison between the PD and fuzzy PD controllers in terms of the CEACS pointing accuracies and control torques is provided.FindingsNumerical results show that the fuzzy PD controller produces a considerable CEACS pointing accuracy improvement for a lower control torque compartment.Practical implicationsCEACS has gained a renew interest because of significant increase in the projected onboard power requirements for future space missions. Therefore, it is of paramount importance to improve the CEACS pointing accuracy itself with a minimum control torque compartment. In fact, this proposed fuzzy PD controller is shown to be a potential CEACS attitude controller.Originality/valueThe fuzzy PD-based CEACS architecture not only provides a better attitude pointing accuracy but also ensures a lower control torque compartment, which corresponds to a lower onboard power consumption.

Nonsingular terminal sliding mode control technique for attitude tracking problem of a small satellite with combined energy and attitude control system (CEACS)

Attitude control and power storage subsystems are two of the essential utilities provided on a spacecraft. As they comprise a significant fraction of a spacecraft mass, a synergism concept that integrates these two into one subsystem can reduce the mass and volume of a spacecraft. The reduction will decrease the total cost of development and deployment of a satellite. A combined energy and attitude control system (CEACS) utilizes flywheels as a means of power storage and simultaneously as actuators. A series of works on CEACS have proposed solutions for attitude control problem of pitch axis. However, their analyses disregarded the high non-linearity involved in the attitude control of a spacecraft. In addition, the proposed controllers' feasibility in the presence of unknown perturbations and uncertainties were not examined. This study proposes a Nonsingular Terminal Sliding Mode (NTSM) control scheme for the attitude tracking control of roll, pitch and yaw axes of a small satellite with CEACS. The nonlinear system is subjected to unknown but bounded disturbances and uncertainties. The Lyapunov stability theorem is used to prove finite-time convergence in both reaching and sliding phases. This proposed method avoids inherited singularity of conventional terminal sliding mode. The numerical analysis provides proof of the controller robustness in rejecting unknown disturbances and keeping the attitude errors within limits under the influence of uncertainties. Results provided by NTSM control method demonstrate the superiority of this sliding mode scheme compared to the previous proposed techniques for attitude control of the CEACS.

Singularity-free integral-augmented sliding mode control for combined energy and attitude control system

A combined energy and attitude control system (CEACS) is a synergized system in which flywheels are used as attitude control actuators and simultaneously as a power storage system. This paper, a subsequent to previous research on CEACS, addresses the attitude-tracking problem. Integral Augmented Sliding Mode Control with Boundary-Layer (IASMC-BL), a locally asymptotically stable controller, is developed to provide a robust and accurate solution for the CEACS’s attitude-tracking problem. The controller alleviates the chattering phenomenon associated with the sliding mode using a boundary-layer technique. Simultaneously, it reduces the steady-state error using an integral action. This paper highlights the uncertainty of inertia matrix as a contributing factor to singularity problem. The inversion of the uncertain inertia matrix in simulation of a spacecraft dynamics is also identified as a leading factor to a singular situation. Therefore, an avoidance strategy is proposed in this paper to guarantee a singular-free dynamics behavior in faces of the uncertainties. This maiden work attempts to employ the singularity-free Integral Augmented Sliding Mode Control with Boundary-Layer (IASMC-BL) to provide a robust, accurate and nonsingular attitude-tracking solution for CEACS.

Sliding Mode Control Techniques for Combined Energy and Attitude Control System

Combined Energy and Attitude Control System (CEACS) is an optimization approach that combines the energy storage system and the attitude control system. With a double counter rotating flywheel simultaneously serving as energy storage device and as attitude control actuator, CEACS requires an accurate control strategy to obtain the mission requirements. In addition, it is important to design the control law to be invariant to uncertainties and disturbances, and guarantee robustness as CEACS inherits these in-orbit uncertainties. This paper presents a nonlinear control employing sliding mode to enhance the CEACS attitude control capability. The mathematical model for the conventional and boundary layer sliding mode controls are developed herein for CEACS. The controller provides enhancement in pointing accuracies, reasonable transient responses and a robustness against uncertainties and in-orbit disturbances.

H∞ control option for a combined energy and attitude control system

A combined energy and attitude control system (CEACS) is a hybrid system that uses flywheels to store energy and provide a simultaneous attitude control in satellites. Previous work appeared in Advances in Space Research (ASR) employing the proportional-derivative (PD) control has proven that CEACS works well and achieves its mission requirement. However, the in-orbit system performance uncertainties present a challenge to the CEACS attitude pointing capability. Thus, this paper complements the previous mentioned work, and focuses on employing the H∞ optimal attitude control solution for the CEACS attitude control enhancement. The mathematical model and numerical treatments for the CEACS H∞ control architecture are presented. Numerical results show that a better attitude pointing accuracy at least up to 0.043° can be achieved with the H∞ control method.

H2 optimal control solution for a combined energy and attitude control system

This addendum is an extension of a series of research work on the combined energy and attitude control system (CEACS) for small satellites. Previous works appeared in Acta Astronautica showed that the CEACS is able to simultaneously perform the attitude control and energy storage task. This addendum focuses on the CEACS attitude control enhancement by employing the H2 optimal control method. Governing equations describing the CEACS H2 attitude control architecture are established. Numerical treatments are performed in order to validate the attitude control option.

Attitude pointing enhancement for combined energy and attitude control system

This paper extends the previous works that appeared in Acta Astronautica. An approach that incorporates the Active Force Control (AFC) technique into a conventional Proportional-Derivative (PD) controller is proposed for a 50 kg small satellite. Numerical treatments are performed to validate the effectiveness of AFC. The attitude control capability of the combined energy and attitude control system (CEACS) is expected to improve. The result shows an important attitude pointing enhancement for the CEACS attitude control task.

Two degree-of-freedom spacecraft attitude controller

Two degree-of-freedom controller is designed together with its governing equations for a spacecraft pitch attitude control. The attitude controller incorporates the Active Force Control (AFC) technique into the conventional Proportional-Derivative (PD) controller based spacecraft pitch attitude loop. The PD-AFC attitude controller is then employed to enhance the attitude pointing of the Combined Energy and Attitude Control System (CEACS). Numerical treatments are performed to validate the effectiveness of AFC, whereby the CEACS attitude performance is analysed from its accuracy point of view. The results show that the PD-AFC attitude control performance is superiorly better than that of the solely conventional PD type.

Hybrid spacecraft attitude control system

The hybrid subsystem design could be an attractive approach for future spacecraft to cope with their demands. The idea of combining the conventional Attitude Control System and the Electrical Power System is presented in this article. The Combined Energy and Attitude Control System (CEACS) consisting of a double counter rotating flywheel assembly is investigated for small satellites in this article. Another hybrid system incorporating the conventional Attitude Control System into the Thermal Control System forming the Combined Attitude and Thermal Control System (CATCS) consisting of a fluid wheel and permanent magnets is also investigated for small satellites herein. The governing equations describing both these novel hybrid subsystems are presented and their onboard architectures are numerically tested. Both the investigated novel hybrid spacecraft subsystems comply with the reference mission requirements. The hybrid subsystem design could be an attractive approach for futurespacecraft to cope with their demands. The idea of combining theconventional Attitude Control System and the Electrical Power System ispresented in this article. The Combined Energy and Attitude ControlSystem (CEACS) consisting of a double counter rotating flywheel assemblyis investigated for small satellites in this article. Another hybrid systemincorporating the conventional Attitude Control System into the ThermalControl System forming the Combined Attitude and Thermal ControlSystem (CATCS) consisting of a fluid wheel and permanent magnets isalso investigated for small satellites herein. The governing equationsdescribing both these novel hybrid subsystems are presented and theironboard architectures are numerically tested. Both the investigated novelhybrid spacecraft subsystems comply with the reference missionrequirements.

Operation for the combined energy and attitude control system

Purpose – An architecture is proposed based on the torque mode operation for the combined energy and attitude control system (CEACS). The CEACS energy storage and attitude control performances are demonstrated.

Onboard errors of the combined energy and attitude control system

This paper extends the previous work appeared in Acta Astronautica. A comparable attitude control architecture is proposed for the combined energy and attitude control system (CEACS). The non-ideal CEACS attitude performance is deeply investigated herein.

Architecture for Combined Energy and Attitude Control System

Combining the energy and attitude control system is a feasible technology for small satellites to improve the space missions. In this Combined Energy and Attitude Control System (CEACS) a double rotating flywheel is used to replace the conventional battery for energy storage as well as to control the attitude of an earth oriented satellite. Each flywheel is to be controlled in the torque mode. The energy and attitude inputs for the flywheels' control architecture are also in the torque mode. All related mathematical representation along with the relevant transfer functions and the required numerical calculation are developed. The goals are to analyze the attitude performance with respect to the ideal and non-ideal test cases for a chosen reference mission.

Flywheel energy storage for spacecraft

Flywheels can serve not only as attitude control devices, but also as energy storage devices, thereby eliminating the need for conventional batteries. Hence, a combined energy and attitude control system (CEACS) consisting of a double counter rotating flywheel assembly is proposed for small satellites in this paper. The energy level in CEACS depends mainly on the flywheels' speeds. Therefore, a specific flywheel energy management strategy has to be implemented to take into account the limitations of the flywheels, which has not been established until today.

A combined energy and attitude control system for small satellites

The idea of combining the satellite attitude control system and the electrical power system is investigated in this article. The combined energy and attitude control system (CEACS) concept is based on a double counter rotating flywheel assembly serving simultaneously for the satellite energy storage and attitude control tasks. In the past years, this synergistic system was proposed for larger spacecraft, but until today a comprehensive end-to-end system demonstration for small satellites still has not been performed. On this basis, the investigation is narrowed to the consideration for small satellites at the inception of the study. First, the CEACS architecture is presented along with its mathematical models. Then, numerical treatments with a sufficient magnitude are performed, which allow an assessment of the system's merits. The simulation results pertaining to the ideal and non-ideal test cases indicate that the CEACS is judiciously an attractive synergistic system for future small satellites.

Methodology for the development of combined energy and attitude control systems for satellites

The Combined Energy and Attitude Control System (CEACS) is a promising technologically advanced concept for space applications which could replace the conventional separate Electrical Power System (EPS) and Attitude Control System (ACS). In the past years this system was proposed for larger spacecraft but until today neither the feasibility of CEACS on small spacecraft, such as the Micro/Nanosatellites, nor end-to-end system demonstration was performed. Additionally, the existing literature does not emphasize extensively mathematical models for a precise analysis of the CEACS. Therefore, the study presented here deals with an initial investigation of useful models that allow for a systematic analysis of CEACS independent of the satellite types. The concept discussed is based on a double counter rotating flywheel assembly in the pitch axis. For the presentation of the methodology, a reference mission is chosen to demonstrate the feasibility of CEACS on smaller satellites. The capabilities of energy storage and attitude control are especially demonstrated. The critical limitations are analyzed and the simulation results are presented. Finally, the general feasibility of CEACS on Micro/Nanosatellites is discussed.