Gain-Scaled compensation function observer for enhanced adaptive backstepping control of QUAV attitude

By means of a fully actuated system (FAS) approach, this article is concerned with an anti-disturbance tracking control problem toward a class of lumped disturbances containing the model uncertainties and external disturbances. A FAS predictive control with a generalized proportional-integral observer (GPIO) is presented to address this problem. Concretely, a FAS model of discrete-time nonlinear systems with the lumped disturbances is firstly given as a control-oriented one. Then, a GPIO is developed to achieve an accurate estimation for the lumped disturbances by adopting a less conservative disturbance assumption, which provides a better foundation to construct a disturbance preview. Furthermore, an incremental FAS (IFAS) prediction model with a disturbance preview is constructed by utilizing a new type of Diophantine Equation. Dependent on this IFAS prediction model, the multistep ahead predictions can be obtained to minimize an objective function to yield an optimal anti-disturbance controller, such that the desired tracking performance can be guaranteed. The depth analysis derives a sufficient condition for the bounded stability and tracking performance of the closed-loop FASs. The proposed GPIO-based FAS predictive control provides a solution to the spacecraft attitude control for verifying the feasibility.

Suboptimal attitude control of nadir-pointing satellites using magnetic torquers and reduced reaction wheels

Adaptive finite-time second-order sliding mode attitude control for fixed-wing UAVs

This paper develops a guidance control law based on a parametric guiding vector field (GVF) and integrates it with a state-of-the-art acceleration and attitude control architecture for tailsitters. The resulting framework enables a direct comparison between traditional trajectory-tracking guidance and GVF-based path-following guidance using a realistic tailsitter model operating under windy conditions. Through extensive simulations, it is shown that for agile flight scenarios with wind and small initial position error, both guidance strategies achieve comparable tracking performance, indicating that the additional complexity introduced by the GVF formulation is not always justified. However, the GVF-based approach exhibits an advantage when initial deviation from the path is present, yielding smooth and well-behaved convergence toward the desired path. Two additional contributions support this evaluation. First, a modification of the parametric GVF is proposed that guarantees exponential stability of the tracking error dynamics for a single-integrator system. Second, the differential flatness transform of a tailsitter vehicle is extended to account for explicit knowledge of the wind velocity vector.

This paper presents a theoretical framework for analyzing the stability of higher-order attitude control laws on the Special Orthogonal Group SO ( 3 ) . In particular, it considers a class of dynamic state-feedback compensators in which the controller state x K ∈ R n has arbitrary finite dimension. This class of compensators includes, as special cases, several existing geometric nonlinear PID-type attitude controllers in which the dynamic component is an integrator state having dimension 3. As a result, the proposed analytical framework extends existing results on geometric nonlinear PID-type attitude control to more general dynamic state-feedback compensators on SO ( 3 ) . The stability analysis of the higher-order attitude controller is carried out in two main steps. First, a quadratic candidate Lyapunov function is used to obtain sufficient conditions, in the form of bilinear matrix inequalities (BMIs), which ensure that the desired equilibrium of the closed-loop tracking error system is almost globally asymptotically stable (AGAS). Then, a convex relaxation of the proposed conditions is used to obtain sufficient conditions in the form of linear matrix inequalities (LMIs). To reduce conservatism, matrix gains are used for the controller gains as well as the Lyapunov function coefficients. The use of quadratic Lyapunov functions and LMIs is motivated by their ubiquitous use in the design and analysis of dynamic compensators for linear time-invariant (LTI) systems. The applicability of the proposed analytical framework to practical problems on SO ( 3 ) is illustrated by designing a 9-state almost globally asymptotically stabilising attitude controller for an agile multicopter.

To address the limited understanding of the aerodynamic characteristics of bird-inspired flapping-wing aircraft across different flight phases and the unclear flow field interaction mechanisms between the wings and tail, this study performs three-dimensional numerical simulations based on a self-developed prototype using ANSYS Fluent and the overset mesh method. The aerodynamic effects of key tail parameters under different flight conditions are quantitatively evaluated, and the mechanisms of bidirectional wing-tail aerodynamic coupling are investigated. The results show that tail twist has a negligible influence on instantaneous lift and thrust during level flight, with a maximum variation of only 0.2 N, but significantly affects the overall aerodynamic moments of the aircraft. When the tail twist angle increases from 15° to 20°, the pitching moment increases by 6%. In contrast, during climbing flight, the tail pitch angle has a pronounced effect on lift and thrust, and its aerodynamic influence depends strongly on the aircraft angle of attack. At an aircraft angle of attack of 15°, the difference between the maximum and minimum cycle-averaged pitching moments reaches 0.2 N·m. Further analysis of vorticity fields and pressure distributions confirms the existence of distinct wing-tail aerodynamic coupling. The tail not only directly modifies the aerodynamic forces and moments acting on the aircraft but also alters the wing-generated flow structures, while the wing wake simultaneously influences the aerodynamic effectiveness of the tail. This bidirectional wing-tail aerodynamic coupling plays a critical role in shaping the aerodynamic response of the aircraft under different flight conditions. These findings clarify the aerodynamic roles of key tail parameters and reveal the underlying flow field interaction mechanisms across different flight phases, providing a theoretical basis for motion-parameter optimization and precise attitude control of bird-inspired flapping-wing aircraft.

Control of static levitation attitude based on CNF-LADRC for distributed electric-drive maglev car.

Angular acceleration plays a very critical role for the dynamic control of the accurate attitude estimation of the unmanned aerial vehicles (UAVs), which is conventionally acquired by the differentiation of the gyroscope signals. However, this indirect derivation inherently introduces detrimental phase lags and amplifies noise, thereby compromising the control stability of flight control systems. To address these limitations, this work proposes a MEMS-based electrochemical angular accelerometer (EAA) with high performance, enabling a direct and high-fidelity angular acceleration measurement. Through theoretical modeling and finite element optimization, a compact plate-type electrode structure that enhances hydrodynamic resistance and sensitivity was developed with Glass-on-Silicon (GOS) package. The fabricated device (22 × 22 × 25 mm3) achieves a sensitivity of 4.5 V/(rad/s²) and a noise floor of 3.12 × 10−6 (rad/s²)/√Hz at 1 Hz, with an ultra-low power consumption of 2.4 mW. While its intrinsic bandwidth is 0.01–0.2 Hz, a compensation circuit extends the -3 dB operational response to 10 Hz. The performance of the EAA was comprehensively validated, ranging from open-loop turntable performance evaluations to flight tests employing a closed-loop incremental nonlinear dynamic inversion (INDI) controller. The results demonstrate that the EAA yields faster command responsiveness and reduced tracking errors when compared to gyroscope-derived estimates. By establishing a robust architecture for direct, low-latency measurement, this work establishes a direct sensing paradigm for high-fidelity angular acceleration measurement in UAV attitude control.

ADCSim: Software for attitude determination and control system design and simulation

Intelligent attitude control of tunnel boring machine in synchronous operations of excavation and segment assembly

Autonomous dynamic soaring can be used to increase the endurance and range of unmanned aerial vehicles by harvesting energy from the vertical gradient of the horizontal wind. This study aims to develop a guidance and control strategy that allows precise following of an optimal dynamic-soaring path for a glider vehicle. The proposed control architecture combines a geometric path-following guidance law with an SO(3)-based attitude control law. High-fidelity six-degree-of-freedom simulation shows that the proposed method can achieve a position accuracy of 0.1 m for a glider with a wingspan of 2 m while adhering to the constraints present on a glider airframe. The high tracking accuracy makes it possible to conduct autonomous dynamic-soaring operations with patterns that were considered impossible in previous studies, such as a travel pattern mimicking the albatrosses’ dynamic-soaring pattern in close proximity to the ocean surface.

Center-of-Mass and Attitude Control of an Orbital Manipulator: A Novel Control Strategy

This article investigates the smooth control problem of switched fuzzy systems, where the modes asynchronously switch under a partly stochastic sojourn time (PSST) switching signal, i.e., a duration of the sojourn time is governed by a random distribution. The formulated PSST switching signal is composed of a mode-dependent activated time and a duration subject to certain stochastic processes, which covers the conventional (average) dwell time (DT) switching signals or stochastic switching signals as special cases. Considering the measuring and computing delay in mode and membership degree identifying of the fuzzy switched systems, the asynchronous phenomena caused by unmatched case between control and system modes are included in the PSST switching signal, and a detected-mode-based Lyapunov candidate is formulated for the mean-square stability (MSS) and robustness analysis, which has not been considered before. To overcome the undesired control bump between adjacent modes, a multistage membership degree interpolation approach is proposed to obtain a smooth control transition after the asynchronous duration to carry out an anti-asynchronously stochastically smoothly switched fuzzy controller (A2S3-FC), unlike the existing literature that only considers part of the property of the practical systems. The effectiveness and the advantages of the proposed A2S3-FC are verified via a numerical example and a simulation of aerial manipulator attitude control.

Objective: Nutrition is critical for people living with human immunodeficiency virus (PLHIV); nonetheless, nutritional interventions have not been conducted among PLHIV in the Middle East and North Africa region. This study evaluated the effects of a nutrition-related education intervention on total knowledge, attitude, and practice (KAP) scores and on the intake of immune-enhancing foods and nutrients among PLHIV. Methods: Sixty-three PLHIV were recruited from an outpatient HIV clinic in Dubai, United Arab Emirates, between August and November 2023 and randomly assigned to an intervention (n = 31) or control group (n = 32). The intervention group participated in an individualized, six-session nutrition education program based on the Health Belief Model, whereas the control group received usual care plus a nutrition education brochure on HIV nutrition and health. Data were collected at baseline and after the five-month intervention period using validated instruments assessing HIV-related nutrition knowledge, attitudes, and practices. A food frequency questionnaire and two non-consecutive 24 h dietary recalls were used to assess the intake of immune-enhancing nutrients. Results: Post-intervention KAP score distributions differed significantly between the control and intervention groups for knowledge, attitude, and practices (p < 0.001, 0.003, and 0.001, respectively). Immune-enhancing vitamin intake did not differ significantly between groups, except vitamin E, which increased in the intervention group (p = 0.042). Conclusions: The intervention improved participants’ nutrition-related KAP scores but did not increase the intake of immune-enhancing nutrients, except for vitamin E. Further studies are warranted to develop interventions that improve the intake of immune-enhancing nutrients.

Simulation degradation datasets for health prognosis of a control moment gyroscope\u2019s flywheel system

The deployment of Autonomous Underwater Vehicles (AUVs) for ocean observation is one of the important methods in marine scientific research. The stability of AUV attitude control determines the efficiency and safety of underwater operations. In practical systems, the actuators carried by AUVs have saturation, and the saturation of the actuators greatly affects the performance and stability of AUV attitude control. This article designs an anti-windup [Formula: see text] robust state feedback controller and an anti-windup [Formula: see text] robust dynamic output feedback controller for the pitch attitude control of AUVs to solve the pitch attitude control problem of AUVs subject to input constraints. Firstly, building a Linear-parameter varying (LPV) model for the AUV. Then, we design two anti-windup [Formula: see text] robust controllers based on LPV model. Simulation results verify the reasonable of LPV model and the effectiveness of proposed controllers. Proposed controllers can enable the system to quickly reach the desired attitude under input constraints.

In this study, a novel flying legged robot configuration with enhanced obstacle-crossing capability is introduced. Legged robots, especially RHex robots, already possess high obstacle-crossing capability; however, the obstacle size that can be overcome is directly dependent on the leg length. Although stair climbing–descending, obstacle course and inclined surface algorithms have been studied for the RHex robot, flight capability has not been explored. In this study, this improvement is achieved with minimal impact on the RHex’s design by adding just a thruster as an additional propulsion system to propel the robot into flight. The attitude control is realized using the mass actuation of the robot legs, similar to how animals like lizards and cats utilize their limbs or tails as inertial appendages to stabilize their body pitch during mid-air maneuvers. Instead of direct and complete flight control, the aim was a temporary flight similar to obstacle-clearing flights of chickens. Hence, a nonlinear 2D model is developed to investigate the kinematics and dynamics of the RHex robot. Equations of motion are derived, linearized and used in a state feedback regulator design; the regulator is also expanded for reference tracking.

Lead-time composite control of the single-gimbal control moment gyro under multi-source disturbances.

This paper presents a six-degree-of-freedom (6-DOF) fuel-optimal trajectory optimization framework using indirect methods, where both translational and rotational motions are governed by thruster-based actuation. The formulation couples translational and rotational dynamics, which guarantees local optimality of the spacecraft’s roto-translational motion. A representative thruster configuration is used to simulate various mission scenarios, including nominal operations and thruster failure cases. The methodology is demonstrated in the context of a hypothetical large-aperture space telescope in-space servicing and assembly (ISA) mission in a Sun–Earth L2 halo orbit. The paper also introduces an optimal attitude control strategy for the evolving space structure using the thrusters of a distributed multi-agent CubeSat swarm as attitude control actuators. Time-varying inertial properties and no-thrust time interval constraints are incorporated into the optimal attitude control formulation using smooth time-triggered activation functions and continuation. Angular constraints are also incorporated, using additional Lagrange multipliers, to prevent solar exposure of sensitive instruments. Simulation results demonstrate that the proposed 6-DOF formulation achieves fuel-optimal solutions under nominal conditions and generates feasible trajectories under prescribed thruster failure scenarios. The attitude control framework also successfully maintains the orientation of the evolving space structure while satisfying the prescribed constraints, thereby ensuring safe assembly and operations in deep-space ISA missions.