Active Attitude Control Research Articles

Scaling procedure for on-ground testing of a robust attitude and vibration control architecture for a large flexible satellite

The agility of satellites equipped with large and flexible structures, such as solar panels or antennas, poses a significant challenge due to the influence of elastic dynamics on attitude motion. This results in reduced pointing accuracy and dimensional stability of the payload. To address this issue, an Active Collocated Attitude Control (ACAC) system has been developed, utilizing actuators for both the elastic dynamics (distributed piezoelectric devices) and attitude control (ON-OFF thrusters). In the initial phase of the project, the algorithm underwent extensive verification using a high-fidelity numerical model of a spacecraft with two very-low frequency flexible solar panels and a payload consisting of two long booms and a transversal antenna's reflector. The paper focuses on the second phase of the project, which revolves around the experimental verification of the control architecture concept. To achieve this, a scaling procedure employing the dynamic analogy approach was implemented to determine the design parameters of a free-floating platform equipped with elastic appendages. This ensured that the resulting elastic multibody system displayed similar dynamic behavior to the full-scale satellite. Based on the scaling parameters, a test rig was manufactured, and actuators and sensors were optimally positioned. The performance of the ACAC system was then compared to that of traditional benchmark controllers. The results show that the ACAC system demonstrates superior capabilities in performing fast slew maneuvers without developing unstable interactions with the elastic dynamics.

Орбитальная стабилизация динамически вытянутого малого космического аппарата с помощью магнитной системы ориентации

The paper proposes an algorithm for angular motion control of a dynamically elongated spacecraft. The algorithm is based on the direct Lyapunov method using matrix control coefficients. The calculated mechanical torque is implemented using a magnetic attitude control system. Control parameters are selected using Floquet theory to ensure convergence of the motion trajectory to the required one. A numerical study of controlled motion to achieve gravitational attitude equilibrium of a 3U CubeSat is carried out.

Vertically integrated project based method applied to small satellite technology development

Small satellite missions and technology development presents a unique platform for preparing undergraduate engineering students for future careers. University based small satellite projects provide students access to hands-on opportunities to apply theory learned in classes through computational analysis, hardware experimentation, and product design. They also allow students to gain project management skills and see systems engineering and design life cycle from a perspective few semesters long courses and lectures can provide. Since 2017, undergraduates have been involved in the Purdue University team investigating the Film Evaporation MEMS Tunable Array (FEMTA), a novel microthruster that evaporates ultra-pure deionized water to generate thrust and is intended for use as active attitude control on small satellites. This technology development project is well suited for including undergraduates, as the system operation can be easily understood by a student with only an introductory understanding of fluid mechanics. Undergraduates initially investigated single axis rotation control of a model CubeSat and now focus a suborbital payload to test the propellant management system. Undergraduates earn degree credit for aiding the faculty and graduate students in this long-term, multidisciplinary, and vertically-integrated – including students from freshmen to seniors -research project team. Vertically integrating allows students to participate for their entire undergraduate studies, while providing projects with stability and a knowledge base shared amongst many students. While this method can be applied to projects that are not aerospace related, small satellite projects allow students to add a breadth and depth of subject matter to their professional development. This project has included mechanical engineers, aerospace engineers, electrical and computer engineers, and computer science majors. This environment grants students the ability to learn new perspectives and problem-solving techniques from their peers. By requiring students to earn degree credit for project work, students become more invested and develop better professional habits such as proper documentation and communication. Student testimonials have cited this project as an asset while talking with company recruiters and for graduate school applications. The same methods developed on the FEMTA project are also being applied to the Purdue student team that is developing the camera system for the NASA Solar Cruiser mission, with similar success.

Simultaneous design of passive and active spacecraft attitude control using black-box optimization

This paper investigates the simultaneous design of active attitude control and passive attitude compensation mechanism for a spacecraft to satisfy practically-motivated mission objectives and constraints. The expressions of these fitness-related metrics with respect to the design variables are not analytically available, due to the nontrivial interactions between the spacecraft components and the interactions with the environment. Thus, such functions can only be approximately learned from data derived from simulations. We approach this difficult design problem using a black-box optimization (BBO)-based approach, which combines learning and optimizing the objective and constraint functions by design of experiments. The proposed BBO-based approach is assessed in the context of a 3U CubeSat system design with both a passive magnetic attitude compensation and an active reaction wheel-based control, tested on a simulator considering orbital and environmental dynamics. Simulation results and statistical tests compared to other design methods show the capability of the BBO-based approach to provide a design with the best tracking performance while at the same time satisfying ground station communication requirements and power budget.

Attitude Dynamics of Spinning Magnetic LEO/VLEO Satellites

With the growing popularity of small satellites, the interaction with the air in low and especially in very low Earth orbits becomes a significant resource for passive angular stabilisation. However, the possibility of spin motion remains a considerable challenge for missions involving aerodynamically stabilised satellites. The goal of this paper was to investigate the attitude motion of arbitrarily spinning satellites in LEO and VLEO under the action of aerodynamic, gravitational, and magnetic torques, taking into account the aerodynamic damping. Using an umbrella-shaped deployable satellite as an example, the study demonstrated that both regular and chaotic attitude regimes are possible in the attitude motion. The occurrence of chaos was verified by means of Poincaré sections. The results revealed that, to prevent chaotic motion, active attitude control and reliable deployment techniques for aerodynamically stabilised satellites are needed.

Maximization of LEO Nanosatellite's Transmission Capacity to Multiple Ground Stations: Orbit Selection and Requirements on Attitude Control

This article presents the study of an optimized orbital configuration for a three-axis stabilized 6U LEO nanosatellite that accommodates a polarized calibrator designed to transmit a calibrated signal to seven ground telescopes devoted to cosmic microwave background detection with an accepted maximum absolute pointing error of 4 arcmin; visibility windows and revisit time are maximized by orbit selection and active attitude control considering no possibility of orbital mobility. The solution approach is divided into two parts: in the first part, a dedicated sensitivity study is conducted to find the optimal orbital parameters that maximize the mean contact time between the spacecraft and the list of ground telescopes; in the second part the identified promising orbital configurations are propagated to evaluate the attitude change maneuvers needed during the passage above each telescope to guarantee continuous signal transmission. The results of the sensitivity study report the maximum values for the duration and frequency of the CubeSat-to-Ground station visibility periods. The required performance in terms of pointing accuracy and repointing velocity is later used to propose an attitude control loop for precision pointing and to define a commercial off the shelf Attitude Determination and Control System architecture.

Parametric Optimization and Analysis of Power Efficient Magnetorquer Rod Actuator for Nanosatellite

CubeSats are popular nowadays due to their small size as well as low launch and development costs. Also, they are getting popular as an Earth observation satellite. The Earth observational satellites require a good pointing mechanism to point towards the target. Due to the requirement of an accurate pointing mechanism, a precise attitude control is required. Passive control systems are not suitable because of low pointing accuracy, hence active attitude control systems are mostly used. The attitude control mainly consists of actuators, attitude sensors and a controller. Among the various actuators, magnetic actuators are used in Nanosatellites. In magnetic actuators, magnetic field is produced when current passes through the wire, which is used to generate the torque which is then used to control the attitude of the satellite. The magnetorquer can be of various designs and among these magnetorquer rod is one of them which consists of magnetic material as a core and wire winding over it which carries the current. The magnetorquer rod can be optimized by varying different parameters such as core radius, core length, diameter of the wire and applied voltage etc. The analysis is mostly done by analyzing parameters such as torque-power ratio, magnetic field-power ratio with respect to different diameters of wire, power, generated torque, and thermal analysis. The paper also consists of a comparison of magnetorquer design with commercially available magnetorquers.

Finite-time active fault-tolerant attitude control for flexible spacecraft with vibration suppression and anti-unwinding

In this paper, a finite-time active fault-tolerant control scheme is designed for a flexible spacecraft’s attitude control experiencing inertial parametric variations, external disturbances, multiple actuator faults, and estimation errors while suppressing the flexible appendages’ vibrations without using smart vibration suppression actuators. First, relative attitude dynamics of a flexible spacecraft with multiple actuator faults are outlined, and a sliding mode observer is designed to estimate flexible appendages-related vibrations. The proposed fault detection and identification (FDI) strategy can efficiently detect actuator faults, avoiding the false alarms caused by uncertainties and disturbances, and accurately estimate the cumulative fault effects on the spacecraft via Chebyshev neural network (CNN) based estimator. Based on a novel fast nonsingular terminal sliding mode surface, a finite-time, unwinding-free, and adaptive fault-tolerant attitude controller is designed to acclimatize the detected faults and uncertainties effectively, also heeding the errors in the estimation of flexible modes and faults. The spacecraft can carry out the coveted control objective in a definable time, and the stability of the proposed controller is corroborated via Lyapunov techniques. Finally, a comparative simulation analysis with the existing results elucidated the proposed scheme’s efficacy.

Uncertainties and Design of Active Aerodynamic Attitude Control in Very Low Earth Orbit

This paper discusses the design and the performance achievable with active aerodynamic attitude control in very low Earth orbit, i.e., below 450 km in altitude. A novel real-time algorithm is proposed for selecting the angles of deflection of aerodynamic actuators providing the closest match to the control signal computed by a selected control law. The algorithm is based on a panel method for the computation of the aerodynamic coefficients and relies on approximate environmental parameters estimation and worst-case scenario assumptions for the re-emission properties of space materials. Discussion of results is performed by assuming two representative pointing maneuvers, for which momentum wheels and aerodynamic actuators are used synergistically. A quaternion feedback proportional-integral-derivative (PID) controller implemented in discrete time is assumed to determine the control signal at a sampling frequency of 1 Hz. The outcome of a Monte Carlo analysis, performed for a wide range of orbital conditions, shows that the target attitude is successfully achieved for the vast majority of the cases, thus proving the robustness of the approach in the presence of environmental uncertainties and realistic attitude hardware limitations.

Active attitude control for microspacecraft; A survey and new embedded designs

Novel technologies and design techniques of the active attitude control systems (ACS) for microspacecraft are briefly covered in this survey. Electric propulsion (EP) thrusters for satellites orbit correction and interplanetary vehicles acceleration have recently emerged as the focal point and front subject in propulsion fields due to their low mass, low cost and high specific impulse. Therefore, micro propulsion thrusters are explored for small satellites in terms of its performance, lifetime and future prospects. The focus of the review is at the center of research published in the last few years and state-of-the-art design concepts in terms of control, reliability, fault analysis and response to failure has been discussed for reaction wheels and magnetorquers. Finally, novel embedded planar magnetorquers which are integrated inside the internal layers of PCB for providing attitude maneuverability to various small satellites are discussed and simulated for critical tasks such as damping the initial angular velocities after vehicle launch. As the proposed magnetorquers are integrated in the form of copper traces, thermal analyses are done to maintain the temperature gradients.

Optimized Design and Analysis of Printed Magnetorquer for a 3-U Nano-Satellite

AbstractAn active attitude control system using a novel six-layer electromagnetic embedded printed magnetorquer for a 3-U nanosatellite is presented in this paper. The proposed design was optimized...

Solar sail attitude control using shape variation of booms

Active attitude control of solar sails is required to control the direction of the force generated by Solar Radiation Pressure (SRP). It is desirable to control the attitude through propellant-free means. This paper proposes a new method for attitude control of solar sails: A boom consisting of “smart” structural material can be deformed by the piezoelectric actuator, and Solar Radiation Pressure torque will be generated due to shape variation of sail membrane caused by boom deformation. The method has the advantages of simple structure, small disturbance and small additional load, and is not limited by the size of the solar sail. The case of rendezvous with the Asteroid 2000 SG344 is used to verify the attitude control around the pitch and yaw axes.

Aerodynamic Comparison of Two Concept Capsules in Earth Reentry

Aerodynamics of two capsules of different conception both equipped with aerodynamic control surfaces has been compared at high-altitude Earth reentry path. The capsules are comparable in size but completely different in shape and, hence, in the aerodynamic behavior. The capsules are: 1) a circular cylinder provided with four flapped fins (finned cylinder), 2) a capsule, here tagged as Reentry Space Vehicle (RSV), very similar in shape and dimensions to the Intermediate eXperimental Vehicle. The study was carried out computationally in hypersonic, rarefied flow in terms of aerodynamic global coefficients (lift, drag, moments, etc.) computed by a three-dimensional direct simulation Monte Carlo code at the altitudes of 100 and 120 km, in the interval of angles of attack 0–50 deg and with flap angles of 0 and 20 deg. Computations verified that while RSV exerts a stronger aerodynamic force for the reduction of the capsule reentry velocity, the finned cylinder is better in terms of the attitude control capability. In fact, equilibrium of the finned cylinder is stable at zero angle of attack at the two altitudes, whereas the angle of attack of stable equilibrium of RSV changes with altitude. Hence, RSV needs to be provided with an active attitude control system.

Active disturbance rejection attitude control of unmanned quadrotor via paired coevolution pigeon-inspired optimization

PurposeThe purpose of this paper is to develop a novel active disturbance rejection attitude controller for quadrotors and propose a controller parameters identification approach to obtain better control results.Design/methodology/approachAiming at the problem that quadrotor is susceptible to disturbance in outdoor flight, the improved active disturbance rejection control (IADRC) is applied to design attitude controller. To overcome the difficulty that adjusting the parameters of IADRC controller manually is complex, paired coevolution pigeon-inspired optimization (PCPIO) algorithm is used to optimize the control parameters.FindingsThe IADRC, where nonlinear state error feedback control law is replaced by non-singular fast terminal sliding mode control law and a third-order tracking differentiator is designed for second derivative of the state, has higher control accuracy and better robustness than ADRC. The improved PIO algorithm based on evolutionary mechanism, named PCPIO, is proposed. The optimal parameters of ADRC controller are found by PCPIO with the optimization criterion of integral of time-weighted absolute value of the error. The effectiveness of the proposed method is verified by a series of simulation experiments.Practical implicationsIADRC can improve the accuracy of attitude control of quadrotor and resist external interference more effectively. The proposed PCPIO algorithm can be easily applied to practice and can help the design of the quadrotor control system.Originality/valueAn improved active disturbance rejection controller is designed for quadrotor attitude control, and a hybrid model of PIO and evolution mechanism is proposed for parameters identification of the controller.

Extended Lifetime of CubeSats in the Lower Thermosphere with Active Attitude Control

A wide variety of missions could be enabled by extended orbital flight in extreme low Earth orbit, defined as an altitude range of 150–250 km. This study investigates the feasibility of a nanosatellite (mass ) using a propulsive, attitude control system in conjunction with a primary propulsion system to extend mission life. The primary propulsion system consists of a pair of electrospray thrusters providing a combined thrust of 0.12 mN at 1 W. Pulsed plasma thrusters are used for attitude control. The mission consists of two phases. In Phase I, a 4U CubeSat is deployed from a 414 km orbit and uses the primary propulsion system to deorbit to an initial altitude within the targeted range of . Phase I lasts 12.73 days, with the propulsion system consuming 5.6 g of propellant to deliver a of 28.12 m/s. In Phase II the mission is maintained until the remaining 25.2 g of propellant is consumed. Phase II lasts for 30.27 days, corresponding to a of 57.22 m/s with a mean altitude of 244 km. Using this approach, a primary mission life of 30.27 days could be achieved, compared with 3.1 days without primary propulsion.

Adaptive-based linear active disturbance rejection attitude control for quadrotor with external disturbances

This paper proposes a linear active disturbance rejection control (LADRC) scheme for a quadrotor unmanned aerial vehicle (UAV) with external disturbances based on adaptive control to address the attitude control problem. Firstly, the dynamic model of the quadrotor is established, and LADRC is used to control the altitude, yaw angle, pitch angle and roll angle of the quadrotor UAV affected by external disturbances, which enhances the anti-disturbance ability of the system. In addition, adaptive control is introduced to solve the problem of difficult parameter tuning in LADRC. Then, the stability of the system is demonstrated by Lyapunov theory. Finally, the simulation results verify the effectiveness of the proposed control scheme under external disturbances.

Optimized Design of Embedded Air Coil for Small Satellites with Various Dimensions

Active attitude control systems using a novel six-layer electromagnetic embedded printed air coil for small satellites with various dimensions are presented in this paper. The proposed designs are optimized in terms of available area, generated torque, power dissipation, and generated magnetic dipole moment. The designed printed air coils are the best choice for small satellites’ attitude stabilization in terms of their modularity, reconfigurability, lower cost, lesser space occupation, and low mass. The printed air coil is designed and analyzed for three small satellites with dimensions 10, 13, and . The design is implemented with commercial off-the-shelf microdevices that are inexpensive, reliable, and easily accessible. The printed air coil is integrated in internal layers of printed circuit board, which does not require additional space on the spacecraft. The proposed air coil with additional configurability features (, hybrid) provides more flexibility to the design aspects by changing the arrangement through the onboard processor according to mission requirements. Electrothermal analysis of the air coil module is done to keep the thermals in check and validate its feasibility. Time-varying rotational operation of nanosatellites is performed to test the rotation time for spin-stabilized satellites. Significant performance parameters like generated magnetic moment, resultant torque, and power dissipation are evaluated and compared with the already commercial state-of-the-art.

A New Method Based on a Multilayer Perceptron Network to Determine In-Orbit Satellite Attitude for Spacecrafts without Active ADCS Like UVSQ-SAT

Climate change is largely determined by the radiation budget imbalance at the Top Of the Atmosphere (TOA), which is generated by the increasing concentrations of greenhouse gases (GHGs). As a result, the Earth Energy Imbalance (EEI) is considered as an Essential Climate Variable (ECV) that has to be monitored continuously from space. However, accurate TOA radiation measurements remain very challenging. Ideally, EEI monitoring should be performed with a constellation of satellites in order to resolve as much as possible spatio-temporal fluctuations in EEI which contain important information on the underlying mechanisms driving climate change. The monitoring of EEI and its components (incoming solar, reflected solar, and terrestrial infrared fluxes) is the main objective of the UVSQ-SAT pathfinder nanosatellite, the first of its kind in the construction of a future constellation. UVSQ-SAT does not have an active determination system of its orientation with respect to the Sun and the Earth (i.e., the so-called attitude), a prerequisite in the calculation of EEI from the satellite radiation measurements. We present a new effective method to determine the UVSQ-SAT’s in-orbit attitude using its housekeeping and scientific sensors measurements and a well-established deep learning algorithm. One of the goals is to estimate the satellite attitude with a sufficient accuracy for retrieving the radiative fluxes (incoming solar, reflected solar, terrestrial infrared) on each face of the satellite with an uncertainty of less than ±5 Wm−2 (1σ). This new method can be extended to any other satellites with no active attitude determination or control system. To test the accuracy of the method, a ground-based calibration experiment with different attitudes is performed using the Sun as the radiative flux reference. Based on the deep learning estimation of the satellite ground-based attitude, the uncertainty on the solar flux retrieval is about ±16 Wm−2 (1σ). The quality of the retrieval is mainly limited by test conditions and the number of data samples used in training the deep learning system during the ground-based calibration. The expected increase in the number of training data samples will drastically decrease the uncertainty in the retrieved radiative fluxes. A very similar algorithm will be implemented and used in-orbit for UVSQ-SAT.

Controllable liquid crystal diffractive sail and its potential applications

This paper introduces a new type of diffractive solar sail composed of liquid crystal optical phased arrays, which control the thrust through electric modulation. The main feature of the proposed liquid crystal diffractive sail is its capability of generating a continuously variable and actively controllable tangential radiation pressure at the sun-facing attitude. The principles governing the generation of radiation pressure by electric modulation of the liquid crystal optical phased array under a broad spectrum of solar radiation are derived by considering a periodical voltage distribution analogous to a reflection step-shaped binary phase grating. Then the reliability of the theoretical model of radiation pressure is verified through comparison with finite-difference time-domain (FDTD) simulation results. A sun-facing liquid crystal diffractive sail may be utilized to replace the reflective sail in space missions by taking the advantage that no active attitude control of the sail surface towards sunlight is required. We also study the attitude control strategy of the proposed diffractive sail along its normal axis, allowing for the direction of tangential radiation pressure to be varied without changing its sun-facing attitude.

Active Disturbance Rejection Attitude Control for Hypersonic Vehicle Based on Intelligent Stochastic Robust Optimization Method

This paper designs a double-loop cascade active disturbance rejection control (ADRC) to overcome the external disturbances and parameter uncertainty during hypersonic vehicle flight. The vehicle attitude angle and attitude angular velocity are regulated in outer loop and inner loop, respectively. A stochastic robust approach is employed to further tune the ADRC parameters for better control performances. The Monte Carlo sampling of uncertain parameter is adopted to evaluate the stochastic robust performance. An improved differential evolution algorithm that combines neighborhood field optimization and triangular mutation is employed as the numerical solver. Simulation results show that the ADRC controller with optimized parameters manifests improved robustness as well as good control performances.