Non-cooperative Target Research Articles

Appointed-time safety-guaranteed control for spacecraft flying around non-cooperative target based on fully actuated system theory

Oriented to the control problem of the spacecraft flying around the non-cooperative target, an appointed-time safety-guaranteed control method based on the fully actuated system theory is proposed considering the effects of external disturbances and undesired orbital manoeuvres of the non-cooperative target. First, the relative motion dynamics model is established based on the Line-of-sight (LOS) frame and then transformed into the fully actuated form to reduce the complexity of controller design. Furthermore, an appointed-time safety-guaranteed controller is designed to guarantee the appointed-time convergence and flight safety of the fly-around system. Finally, the effectiveness and robustness of the designed control method are verified by three groups of fly-around simulations.

Image Segmentation Solutions for Improved Non-Cooperative Target Recognition

The number of failed satellites in space is increasing, and they need to be fueled through space docking to extend their life or clean them out of orbit. Visual measurement is widely used in the docking session because of its real-time performance and economy, but the collected images will have background interference, which directly leads to the degradation of the accuracy of visual measurement. Reduce the difficulty of subsequent image processing by solving these problems. For the non-cooperative target of the star-arrow docking ring and the solar sail panel, which are two significant targets, this paper is based on target detection, according to the image difference, binarization, morphological operations and other methods to complete the accurate segmentation of the two targets, which can be more accurately complete the target detection, and the image segmentation effect is obvious. The target image obtained by image segmentation does not contain background interference, which is convenient for feature extraction and matching of the image.

Event‐driven fault‐tolerant attitude tracking control of spacecraft for noncooperative target interest surface

AbstractThis paper explores the problem of relative attitude stabilization between a noncooperative target interest surface (NCTIS) and a bandwidth‐restricted spacecraft subjected to parameter uncertainties, exogenous disturbance, actuator faults, and input saturation. The proposed angular velocity estimator provides the rotational angular velocity of NCTIS. The proposed control scheme uses a dynamic surface control framework with the finite time disturbance observer to attenuate multi‐source disturbances, and it deals with the restricted communication resources by employing a dynamic event‐triggered mechanism. The presented scheme relaxes the prior upper bound of total disturbance and improves the traditional event‐triggered technique. Stability analysis shows the ultimate uniform boundedness of the closed‐loop system's state trajectory. In addition, the Zeno‐free behavior can be guaranteed in the design. Comparing numerical simulation results with advanced techniques shows the effectiveness of the proposed scheme.

Multiple Noncooperative Targets Encirclement by Relative Distance-Based Positioning and Neural Antisynchronization Control

From prehistoric encirclement for hunting to GPS orbiting the earth for positioning, target encirclement has numerous real world applications. However, encircling multiple non-cooperative targets in GPS-denied environments remains challenging. In this work, multiple targets encirclement by using a minimum of two tasking agents, is considered where the relative distance measurements between the agents and the targets can be obtained by using onboard sensors. Based on the measurements, the center of all the targets is estimated directly by a fuzzy wavelet neural network (FWNN) and the least squares fit method. Then, a new distributed anti-synchronization controller (DASC) is designed so that the two tasking agents are able to encircle all targets while staying opposite to each other. In particular, the radius of the desired encirclement trajectory can be dynamically determined to avoid potential collisions between the two agents and all targets. Based on the Lyapunov stability analysis method, the convergence proofs of the neural network prediction error, the target-center position estimation error, and the controller error are addressed respectively. Finally, both numerical simulations and UAV flight experiments are conducted to demonstrate the validity of the encirclement algorithms. The flight tests recorded video and other simulation results can be found in <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://youtu.be/B8uTorBNrl4</uri>

Research on game strategy of spacecraft chase and escape based on adaptive augmented random search

To solve the problem of the survival differential policy interception between a spacecraft and a non-cooperative target pursuit game, the pursuit game policy is studied based on reinforcement learning, and the adaptive-augmented random search algorithm is proposed. Firstly, to solve the sparse reward problem of sequential decision making, an exploration method based on the spatial perturbation of parameters of the policy is designed, thus accelerating its convergence speed. Secondly, to avoid the possibility of falling into local optimum prematurely, a novelty degree function is designed to guide the policy update, enhancing the efficiency of data utilization. Finally, the effectiveness and advancement of the exploration method are verified with numerical simulations and compared with those of the augmented random search algorithm, the proximal policy optimization algorithm and the deep deterministic policy gradient algorithm.

Classification and Recognition Method of Non-Cooperative Objects Based on Deep Learning.

Accurately classifying and identifying non-cooperative targets is paramount for modern space missions. This paper proposes an efficient method for classifying and recognizing non-cooperative targets using deep learning, based on the principles of the micro-Doppler effect and laser coherence detection. The theoretical simulations and experimental verification demonstrate that the accuracy of target classification for different targets can reach 100% after just one round of training. Furthermore, after 10 rounds of training, the accuracy of target recognition for different attitude angles can stabilize at 100%.

Skeleton-based coordinate system construction method for non-cooperative targets

Due to the lack of structure and part information in non-cooperative targets, the task of pose estimation suffers from unstable and unreliable initial coordinate system. In this paper, we introduce a curve-skeleton-based method to construct the robust coordinate system automatically for non-cooperative targets. First, a nonmanifold-Laplacian-based method is proposed to extract the curve skeleton from point clouds. The proposed method solves the over-contraction problem while preserves the topology and structure of skeleton well during point clouds contraction. Additionally, we create the skeleton graph to detect the skeleton structure and key points automatically. Then, the detected skeleton feature is used to construct target coordinate system, and improve the stability and robustness. Specifically, a real-scan dataset is constructed in this paper, and the proposed point cloud contraction method outperforms previous methods in structural representation and visualization. The mean rotation error of proposed coordinate system construct method performs 0.1249° and 1.2135° in 0%–30% noise ratio of distortions and outliers, and performs 7.04° and 4.21° in real-scan aircraft and satellite datasets. The results in complete and incomplete datasets verify the robustness and reliability of our skeleton-based coordinate system.

Near-infrared H2S telemetry system under non-cooperative target with a novel mixed heterodyne optical structure scheme for high efficiency

A gas leakage telemetry system under non-cooperative target was designed and developed based on laser absorption spectroscopy technology, targeting the combination frequency absorption band of Hydrogen sulfide (H2S) gas molecules. A distributed feedback (DFB) laser centered at 1578 nm was adopt, with mature packaging process and high market maturity. The returned signal of diffuse reflection is extremely weak, decreasing exponentially with the increase of telemetry distance, and direct detection technology is difficult to achieve ideal performance at telemetry distance and lower detection limit. Thus, heterodyne detection technology was introduced to significantly amplify diffuse reflection signal and improve the signal-to-noise ratio (SNR) of telemetry system. For further detection sensitivity, wavelength modulation spectroscopy (WMS) technology was combined to suppress background noise through the electrical modulation of DFB laser. Alternating signal was applied to the laser to alter its output characteristics during the process of laser oscillation. Compared with exterior modulation methods, this interior modulation method does not require additional modulator, which avoids optical loss and is more economical. Combining the advantages of fiber structure and space optical path structure, a novel mixed heterodyne optical structure which was more applicable to this system was independently designed after the specific analysis of main noise sources. Then, the effect of heterodyne detection technology was verified in contrast of direct detection technology. Sensor performance was validated through calibration and stability experiments. The limit of detection (LoD) reached a minimum of 3.44 parts-per-million (ppm·m) with a 98 s averaging time. And the packaged system was fully capable of detecting the hazardous critical concentration of H2S and acting as an alarm mechanism.

Noncooperative Target Finite-Time Surrounding Control of Spacecraft Formation

This paper proposes a novel distributed control method for surrounding a noncooperative target that has maneuverability by spacecraft formation. A relative orbit error dynamic model between the target and the formation is established dependent on a reference spacecraft under the 2-body assumption. To estimate and compensate for the target’s control input rapidly, a novel finite-time extended state observer is developed. It is stable in the sense of fast finite-time uniformly ultimately bounded stability. A fast terminal sliding mode controller is proposed for finite-time convergence of the system. Simulation examples are implemented to show the effectiveness of proposed algorithm.

Parameter Precise Estimation Technology of Active Segment of Non-cooperative Targets Based on Long Short-Term Memory

Traditional algorithms do not fully utilize the timing information of non-cooperative targets, and setting too many motion parameters can lead to complex dynamic model calculations. This paper proposes a long short-term memory (LSTM) network-based method for estimating the parameters of the active segment of the non-cooperative target under single-satellite observation. Based on the simulation training set of the active segment of the non-cooperative target, the network parameters of the LSTM network are designed, the motion characteristics of the active segment of the non-cooperative target are fully excavated through data-driven methods, and the candidate cutting trajectories are screened and predicted to realize the estimation of the motion parameters of the active segment of the non-cooperative target under the condition of single-satellite observation. The experimental results show that the estimation method proposed in this paper can effectively deal with the inaccurate problem with the non-cooperative target’s active segment motion model established under the condition of single-satellite observation, obtain more accurate active segment motion parameters, and provide a feasible new idea and method for the parameter estimation of the active segment of the non-cooperative target under the single-satellite observation.

High-Resolution BVLOS Radar Imaging Method for Non-Cooperative Complex Maneuvering Targets

High-Resolution BVLOS Radar Imaging Method for Non-Cooperative Complex Maneuvering Targets

CMTI: Non-line-of-sight Radar Imaging for Non-cooperative Corner Motion Target

CMTI: Non-line-of-sight Radar Imaging for Non-cooperative Corner Motion Target

An Omnidirectional Compliant Docking Strategy for Non-cooperative On-orbit Targets: Principle, Design, Modeling and Experiment

An Omnidirectional Compliant Docking Strategy for Non-cooperative On-orbit Targets: Principle, Design, Modeling and Experiment

3-D High-Resolution ISAR Imaging for Noncooperative Air Targets

3-D High-Resolution ISAR Imaging for Noncooperative Air Targets

Distance-Based Multiple Noncooperative Ground Target Encirclement for Complex Environments

Distance-Based Multiple Noncooperative Ground Target Encirclement for Complex Environments

Dual-Frequency Phase Unwrapping for 3D InISAR Imaging of Non-Cooperative Targets

Dual-Frequency Phase Unwrapping for 3D InISAR Imaging of Non-Cooperative Targets

Lightweight Network-Based End-to-End Pose Estimation for Noncooperative Targets

Lightweight Network-Based End-to-End Pose Estimation for Noncooperative Targets

BiGAT: A Model for Recognizing Motion Intentions of Space Non-Cooperative Targets

BiGAT: A Model for Recognizing Motion Intentions of Space Non-Cooperative Targets

Anti-unwinding Twistor-based Finite-time Control for Flying Around a Non-cooperative Target

An integrated attitude and orbit finite-time control based on anti-unwinding twistor representation for flying-around with non-cooperative target is proposed in this paper. Firstly, an integrated attitude and orbit model based on traditional twistor representation is established for non-cooperative flying-around problem with complex initial situation. Secondly, an anti-unwinding representation is proposed to avoid the unwinding phenomenon. Thirdly, a finite-time controller in the framework of the anti-unwinding twistor representation is designed to guarantee the spacecraft to reach the desired state quickly. Finally, the effectiveness of the proposed method is verified by numerical simulations.

Adaptive hybrid Kalman filter for attitude motion parameters estimation of space non-cooperative tumbling target

Attitude motion parameters estimation of the space non-cooperative tumbling target is the premise of the on-orbit target capture task. However, existing methods cannot balance the estimation accuracy and efficiency. In this paper, an adaptive hybrid Kalman filter is presented to estimate the attitude, angular velocity and inertia motion parameters of the space non-cooperative tumbling target. First, the dynamic model of the non-cooperative tumbling target is derived, and the nonlinear discrete state-space equation is obtained. Then, a hybrid Kalman filter is designed by combining the extended Kalman filter and the unscented Kalman filter. The adaptive technique is introduced to track time-varying uncertain measurement noise caused by complex space disturbances. After that, based on the first-order linearization technique, the sufficient condition for the local convergence of the proposed method is proved. Finally, the numerical simulation experiment was conducted to compare the proposed method with the adaptive extended Kalman filter and the adaptive unscented Kalman filter. The experimental results show that the estimation accuracy of the proposed method is much higher than that of the adaptive extended Kalman filter and slightly lower than that of the adaptive unscented Kalman filter, and the iteration-average Central-Processing-Unit time is 64.2% smaller than that of the adaptive unscented Kalman filter and slightly longer than that of the adaptive extended Kalman filter. The proposed method achieves a much higher accuracy with a slight loss of iteration-average Central-Processing-Unit time.