Attitude Control Task Research Articles

Attentional Tunneling in Pilots During a Visual Tracking Task With a Head Mounted Display.

We examined whether active head aiming with a Helmet Mounted Display (HMD) can draw the pilot's attention away from a primary flight task. Furthermore, we examined whether visual clutter increases this effect. Head up display symbology can result in attentional tunneling, and clutter makes it difficult to identify objects. Eighteen military pilots had to simultaneously perform an attitude control task while flying in clouds and a head aiming task in a fixed-base flight simulator. The former consisted of manual compensation for roll disturbances of the aircraft, while the latter consisted of keeping a moving visual target inside a small or large head-referenced circle. A "no head aiming" condition served as a baseline. Furthermore, all conditions were performed with or without visual clutter. Head aiming led to deterioration of the attitude control task performance and an increase of the amount of roll-reversal errors (RREs). This was even the case when head aiming required minimal effort. Head aiming accuracy was significantly lower when the roll disturbances in the attitude control task were large compared to when they were small. Visual clutter had no effect on both tasks. We suggest that active head aiming of HMD symbology can cause attentional tunneling, as expressed by an increased number of RREs and less accuracy on a simultaneously performed attitude control task. This study improves our understanding in the perceptual and cognitive effects of (military) HMDs, and has implications for operational use and possibly (re)design of HMDs.

Design concepts and control algorithm to minimize the control effort for earth-orbit-raising solar sails

This paper presents novel design concepts and a robust sliding mode control (RSMC) algorithm for a solar sail optimized for an Earth-orbit-raising demonstration mission. The design of the solar sail is focused on minimizing mission difficulty and control effort during the Earth-orbit-rising mission. To this end, a gravity-stabilized long boom and one-sided black-coating film are introduced in the solar sail system, and a reaction wheel is used as a control torque actuator. The strategic combination of these components modifies the attitude control task from 90° back-and-forth pitch motion control for maintaining the proper attitude for receiving solar radiation pressure (SRP) to that of stabilizing the sail attitude perturbed from gravity-stabilized equilibrium. This simplification of the control task can minimize the mission difficulty and control input energy because attitude control is required only for small deviations from the attitude equilibrium, while the one-sided black-coated film with a reflective surface on the opposite side ensures that SRP propulsion effectively pushes the sail toward the orbit-rising direction. Thus, the control torque of the reaction wheel size can be reduced. To validate the Earth-orbit-raising mission performance, a quaternion-based RSMC approach is established for the six degree-of-freedom dynamic model. The simulation results confirm that the proposed solar sail system can stabilize its attitude with minimal control torque energy of the reaction wheels during Earth-orbit-raising missions.

Attitude Takeover Control of Failed Spacecraft via Leader–Followers Adaptive Cooperative Game

In this paper, the problem of microsatellites-based adaptive cooperative game attitude takeover control for a failed spacecraft is investigated. Specifically, a manned microsatellite (leader) and a team of autonomous microsatellites (followers) are ordered to cooperate to complete the attitude control task in an optimal way, in which the control strategy and the cost function (or intent) of the leader are unknown to the followers. Based on the differential game (DG) theory, the microsatellites-based attitude takeover control problem is formulated as a cooperative DG, in which each microsatellite has the individual cost function. A key problem is that the followers must infer the leader’s intent first, that is, retrieve the weighting matrix of the cost function of the leader. To achieve this, a composite adaptive law is introduced for each follower to estimate the feedback gain matrix of the leader by using system state data and the cost functions of other followers; based on this, the leader’s intent is inferred online by minimizing a residual error. Then, the cooperative game control law of each follower is designed by itself, and the Pareto equilibrium of the DG system is achieved. Finally, the effectiveness of the proposed leader–followers adaptive cooperative game control method is verified by a simulation study.

SCA-MADRL: Multiagent deep reinforcement learning framework based on state classification and assignment for intelligent shield attitude control

With the wide application of the shield tunneling method in tunnel engineering, the untimely and incorrect attitude control of shield systems has become an essential factor affecting the quality of shield tunneling. The use of multi-agent deep reinforcement learning (MADRL) algorithm to learn correct and timely shield attitude correction policies is beneficial for handling shield attitude control tasks which are complex and separable. However, the sensing data of the shield systems are complicated and widely distributed, which affects the learning efficiency of the agents. To resolve this problem, this paper proposes a MADRL framework based on state classification and assignment (SCA) for adaptive shield attitude control. SCA-MADRL uses a clustering algorithm to classify states and uses a planning model to make the agent's learning space a consistent state space so that each agent can learn efficiently in its own learning space. The state classification algorithm in the framework can improve the learning efficiency of the agent, and the proposed assignment algorithm can further enhance the learning effect when reusing the agent. This paper verifies the necessity and effectiveness of using task decomposition to implement MADRL for equipment control and provides a practical framework for automated and intelligent shield systems.

ESO-based nonlinear flying boom attitude control with the handling qualities requirement

Attitude control is an important component of the flying boom system and plays a key role in air-to-air refuelling. A flying boom attitude control task is usually constituted by two subtasks. The first is to reject disturbances in the flight environment, and the second is to enhance handling qualities so that the flying boom can be efficiently and safely navigated into the refuelling receptacle by the boom operator. This paper presents a novel extended state observer (ESO)-based nonlinear flying boom attitude controller design method. To solve the first subtask, the ESO is introduced to estimate the disturbances and uncertainties of the flying boom. Based on the estimation, a nonlinear feedback controller is designed to reject the disturbances in real time. With the support of Lyapunov stability criteria, it is proved that the desired attitude trajectories can be bounded tracked by the flying boom under the proposed controller and the closed-loop dynamics of the system converge to a second-order reference model. To solve the second subtask, the parameters of the reference model are selected with desired handling qualities based on a handling qualities criterion of the flying boom. With the proposed controller, the flying boom system can have both high tracking performance and desired handling qualities. Comparisons among the proposed method and the related methods are simulated to reveal that the proposed method performs better in terms of tracking performance and robustness. Besides, a series of experiments are made on a simulator to validate that the proposed controller can achieve the desired handling qualities.

Integrated vibration isolation and attitude control for spacecraft with uncertain or unknown payload inertia parameters

To meet the spacecraft attitude control requirements with high accuracy and stability, all vibrations in the spacecraft should be reduced in appropriate ways. This paper presents an integrated control method for attitude and the vibrations in both high frequency and low frequency in the spacecraft. The integrated control method includes a vibration isolation platform and a modified adaptive attitude control method. The paper presents a vibration isolation platform with magnetic suspension to reduce high frequency vibrations and a parameter design method for the platform. An adaptive control method is presented to reduce low frequency vibrations while accounting for the bandwidth constraint due to the vibration isolation platform. Firstly, a parameter design method is proposed for the vibration isolation platform, and an entire 6×12 dimensional transformation matrix is derived for the case that the inertia of the payload is of the same order of magnitude as that of spacecraft bus. Then, an adaptive attitude controller is presented that accounts for the coupling characteristics of the spacecraft, the vibration isolation platform and the uncertain or unknown payload inertia parameters. To ensure the robustness of the attitude control system and the performance of the vibration isolation system, a method of estimating the initial value of the payload inertia is presented using classical control theory. Finally, numerical simulations demonstrate that the integrated control method presented in this paper can achieve the attitude control task for spacecraft with high accuracy and stability.

Hybrid task priority-based motion control of a redundant free-floating space robot

This paper presents a novel hybrid task priority-based motion planning algorithm of a space robot. The satellite attitude control task is defined as the primary task, while the least-squares-based non-strict task priority solution of the end-effector plus the multi-constraint task is viewed as the secondary task. Furthermore, a null-space task compensation strategy in the joint space is proposed to derive the combination of non-strict and strict task-priority motion planning, and this novel combination is termed hybrid task priority control. Thus, the secondary task is implemented in the primary task’s null-space. Besides, the transition of the state of multiple constraints between activeness and inactiveness will only influence the end-effector task without any effect on the primary task. A set of numerical experiments made in a real-time simulation system under Linux/RTAI shows the validity and feasibility of the proposed methodology.

Full state-feedback solution for a flywheel based satellite energy and attitude control scheme

A hybrid system combining the energy and attitude control task uses flywheels to store energy and control the attitude of small satellites. Various journal papers containing previous works have recognized this combined architecture. However, due to the uncertainties of on-board performances, it is a challenge in terms of attitude pointing accuracy. Therefore, this paper focuses a full state-feedback control solution to increase the satellite attitude performances. Mathematical model and numerical treatments for full state-feedback control of combined energy and attitude regulating scheme for a small satellite are presented. Simulation results show that an enhanced pitch pointing accuracy can be achieved up to 0.0010 for the proposed control approach. The paper contains an over view of a flywheel architecture along with state space representation of the scheme. A brief description of conventional control scheme is also presented with sample simulated results for comparison. Design of a full state-feedback controller and analysis of simulated results are also presented to show the achieved attitude performances specifically.

Satellite cascade attitude control via fuzzy PD controller with active force control under momentum dumping

In this paper, fuzzy proportional-derivative (PD) controller with active force control (AFC) scheme is studied and employed in the satellite attitude control system equipped with reaction wheels. The momentum dumping is enabled via proportional integral (PI) controller as the system is impractical without momentum dumping control. The attitude controllers are developed together with their governing equations and evaluated through numerical treatment with respect to a reference satellite mission. From the results, it is evident that the three axis attitudes accuracies can be improved up to ±0.001 degree through the fuzzy PD controller with AFC scheme for the attitude control. In addition, the three-axis wheel angular momentums are well maintained during the attitude control tasks.

Angular Momentum Based Steering Approach for Control Moment Gyroscopes

With increasing requirements on agile satellite missions, control moment gyroscopes (CMGs) become the actuator of choice due to their high torque amplification capability. In order to handle their inherent singularity issues, many steering laws have been developed that map a desired torque profile to a commanded gimbal rate profile. As CMGs are internal momentum exchange devices, alternative steering laws exist in the angular momentum/gimbal angle domain. In this paper, the two steering approaches are analyzed conceptually and their performance regarding the handling of singularities is evaluated in simulations. For a CMG array in roof configuration, the angular momentum/gimbal angle steering approach proves to be a viable choice for attitude control tasks.

Extreme Learning Machine Assisted Adaptive Control of a Quadrotor Helicopter

Control of quadrotor helicopters is difficult because the problem is naturally nonlinear. The problem becomes more challenging for common model based controllers when unpredictable uncertainties and disturbances in physical control system are taken into account. This paper proposes a novel intelligent controller design based on a fast online learning method called extreme learning machine (ELM). Our neural controller does not require precise system modeling or prior knowledge of disturbances and well approximates the dynamics of the quadrotor at a fast speed. The proposed method also incorporates a sliding mode controller for further elimination of external disturbances. Simulation results demonstrate that the proposed controller can reliably stabilize a quadrotor helicopter in both agitated attitude and position control tasks.

Reconfigurable Flight Control Design for Combat Flying Wing with Multiple Control Surfaces

With control using redundant multiple control surface arrangement and large-deflection drag rudders, a combat flying wing has a higher probability for control surface failures. Therefore, its flight control system must be able to reconfigure after such failures. Considering three types of typical control surface failures (lock-in-place (LIP), loss-of-effectiveness (LOE) and float), flight control reconfiguration characteristic and capability of such aircraft types are analyzed. Because of the control surface redundancy, the aircraft using the dynamic inversion flight control law already has a control allocation block. In this paper, its flight control configuration during the above failures is achieved by modifying this block. It is shown that such a reconfigurable flight control design is valid, through numerical simulations of flight attitude control task. Results indicate that, in the circumstances of control surface failures with limited degree and the degradation of the flying quality level, a combat flying wing adopting this flight control reconfiguration approach based on control allocation could guarantee its flight safety and perform some flight combat missions.

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.

Rolling into Spatial Disorientation: Simulator Demonstration of the Post-Roll (Gillingham) Illusion

Spatial disorientation (SD) is still a contributing factor in many aviation accidents, stressing the need for adequate SD training scenarios. In this article we focused on the post-roll effect (the sensation of rolling back after a roll maneuver, such as an entry of a coordinated turn) and investigated the effect of roll stimuli on the pilot's ability to stabilize their roll attitude. This resulted in a ground-based demonstration scenario for pilots. The experiments took place in the advanced 6-DOF Desdemona motion simulator, with the subject in a supine position. Roll motions were either fully automated with the subjects blindfolded (BLIND), automated with the subject viewing the cockpit interior (COCKPIT), or self-controlled (LEAD). After the roll stimulus subjects had to cancel all perceived simulator motion without any visual feedback. Both the roll velocity and duration were varied. In 68% of all trials subjects corrected for the perceived motion of rolling back by initiating a roll motion in the same direction as the preceeding roll. The effect was dependent on both rate and duration, in a manner consistent with semicircular canal dynamics. The effect was smallest in the BLIND scenario, but differences between simulation scenarios were non-significant. The results show that the effects of the post-roll illusion on aircraft control can be demonstrated adequately in a flight simulator using an attitude control task. The effect is present even after short roll movements, occurring frequently in flight. Therefore this demonstration is relevant for spatial disorientation training programs for pilots.

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.

Lunar lander's three-dimensional translation and yaw rotation motion estimation during a descent phase using optical navigation

Optical navigation for a lunar lander consists of estimating a lander's 3-dimensional (3-D) relative dynamic motion with respect to a preselected landing site using a passive 2-dimensional (2-D) video image sequence. Lunar landing missions require a lander to perform an autonomous accurate landing with simple mechanical structure, easy operation and low cost. These requirements have motivated the need to develop an advanced navigation system. Existing navigation systems trade-off simplicity, accuracy and cost. High accuracy navigation systems typically imply complexity and high cost. In this paper, we consider a scenario where the descending phase starts from an initial altitude of 10 km with a time-of-descent of 100 s. The navigation camera is an off-the-shelf optical instrument used to take the video image sequence of the landing site during the landing phase. It is fed into the motion estimation algorithm to be processed. The continuous wavelet transform (CWT) is used to analyse each image frame of the input digital video image sequence. The output is a 2-D video image motion trajectory map, which represents the projection motion of the landing site. The 2-D video image motion is projected back to the 3-D lander's relative motion based on a geometric analysis. The outputs of this estimation algorithm are the 3-D attitude motion parameters of the lander at a time corresponding to an image being taken. The attitude determination and control system (ADCS) of the lander uses these data to perform the lander's attitude control task. In this article, we provide the motion modelling for a lunar lander during the descending phase. The projection of a 3-D planar to 2-D image plane is analysed which build the correspondence between the 3-D lander's motion and the 2-D image motion. This link provides the evidence for the geometry analysis. CWT is reviewed and CWT for video image sequence analysis is also introduced. Numerical simulation of the estimated 2-D video image sequence under the lander performing a 3-D translation and yaw rotation during the terminal descent are shown to verify the proposed concepts. The analysis of the results show that the proposed method achieves highly accurate 2-D video image motion estimation of less then 1% error with significant savings of cost, mass and volume. It leads to the accurate estimation of the lander's 3-D relative motion with respect to the landing site.

Effects of Heave Washout Settings in Aircraft Pitch Disturbance Rejection

In most moving-base flight simulators, the simulated aircraft motion needs to be filtered with motion washout filters to keep the simulator within its limited motion envelope. Translational motion in particular requires filtering, as the low frequency components of the vehicle motion tend to quickly drive simulators toward their motion bounds. Commonly, linear washout filters are therefore used to attenuate the simulated motion in magnitude and in phase. It is found in many studies that the settings of these washout filters affect pilot performance and control behavior. In most of these studies, no comparison to a case with one-to-one motion cues is performed, as a result of the limited motion envelope of the used simulators. In the current study, an experiment was performed in the SIMONA Research Simulator at Delft University of Technology to investigate the effects of heave washout settings on pilot performance and control behavior in a pitch attitude control task. In addition to rotational pitch motion, heave accelerations at the pilot station that result directly from aircraft pitch were evaluated. This heave motion component could be supplied one-to-one in the simulator due to the modest size of the aircraft model, a Cessna Citation I business jet. The experiment revealed that pilot performance and control activity both increased significantly with increasing heave motion fidelity. An analysis of pilot control behavior using pilot models indicated that the enhanced performance was caused by an increase in the magnitude with which pilots responded to visual and physical motion stimuli and a decrease in the amount of visual lead that was generated by the pilots.

In-orbit attitude actuation using solar panels

A specific technique is developed to wield the internal disturbance torque caused by the solar panel actuation for spacecraft attitude control tasks. This work is the maiden work towards integrating the attitude control and the solar tracking tasks, forming a combined attitude and solar tracking system. The feasibility of this concept for spacecraft is proven and eventually the combined concept is validated. A technical proof is presented corresponding to the end-to-end system demonstration. The investigation starts with the determination of the solar tracking constraints. Then, the mathematical models describing the attitude and solar tracking are established, and eventually the onboard architecture is implemented. The numerical treatments using Matlab™ were performed to evaluate the developed onboard architecture. The simulation results are discussed especially from the attitude control standpoint. The integrated system complies very well with the reference mission requirements.

Three-axis air-bearing based platform for small satellite attitude determination and control simulation

A frictionless environment simulation platform, utilized for accomplishing three-axis attitude control tests in small satellites, is introduced. It is employed to develop, improve, and carry out objective tests of sensors, actuators, and algorithms in the experimental framework. Different sensors (i.e. sun, earth, magnetometer, and an inertial measurement unit) are utilized to assess three-axis deviations. A set of three inertial wheels is used as primary actuators for attitude control, together with three mutually perpendicular magnetic coils intended for desaturation purposes, and as a backup control system. Accurate balancing, through the platform’s center of mass relocation into the geometrical center of the spherical air-bearing, significatively reduces gravitational torques, generating a virtually torque-free environment. A very practical balancing procedure was developed for equilibrating the table in the local horizontal plane, with a reduced final residual torque. A wireless monitoring system was developed for on-line and post-processing analysis; attitude data are displayed and stored, allowing properly evaluate the sensors, actuators, and algorithms. A specifically designed onboard computer and a set of microcontrollers are used to carry out attitude determination and control tasks in a distributed control scheme. The main components and subsystems of the simulation platform are described in detail.

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.