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In this paper, the controllable set of long-distance guidance segment trajectories for Earth departure circumlunar rendezvous is investigated. Firstly, the mathematical model of controllable set is given according to the long-distance guidance dynamics process. Second, on the basis of the long-distance guidance trajectory design, the controllable set calculation is transformed into a multi-objective nonlinear optimal control problem, and the concept of loosely controllable set is introduced and a controllable set algorithm is proposed. Thirdly, the accuracy of the algorithm is verified by comparing the simulation example with the point design results in other literatures, which are within the envelope of the controllable set in this paper. Finally, the parameter characteristics of the controllable set of long-distance guidance trajectory are analyzed. The conclusions of the study can provide an important reference for the design of long-distance guidance trajectories in future manned lunar landing or lunar exploration missions.

To ensure the successful completion of the manned spacecraft flight missions during China Space Station phase, an analysis of the mission characteristics was conducted. In response to the challenges posed by extended in-orbit flight duration, complex and variable external thermal flux, docking at different ports of the space station, new emergency rescue missions, high precision landing requirements, and efficient earth-to-space transportation, the following coping strategies were proposed, including: implementing long-life design to accommodate extended missions, actively temperature controlling and passive thermal insulation for temperature-sensitive equipment, developing all-directional rendezvous and docking designs, adding emergency rescue spacecraft on the ground, upgrading the re-entry guidance and control methods, and adopting autonomous rapid rendezvous and rapid return technologies. These strategies have been successfully implemented during the space station phase, ensuring the successful completion of the Shenzhou-12 to Shenzhou-18 crewed spacecraft missions. The results demonstrate that the analysis of the mission characteristics was accurate, and the proposed countermeasures are reasonable and feasible, effectively ensuring the safety and reliability of the crewed spaceflight missions for China Space Station.

Chronic total occlusion percutaneous coronary intervention (CTO-PCI) has made significant progress with the retrograde approach, particularly when antegrade techniques are insufficient or not clinically indicated. Despite its advantages, the conventional externalization process carries some notable challenges, including procedural complexity, increased equipment requirements, and elevated risk of rupture of fragile collateral vessels. This article examines the \"deep dive rendezvous\" or DDR technique that we propose in great detail. This novel interventional solution builds on the previously elaborated rendezvous approaches, however, with the added value of offering an enhanced guidewire support through deep intubation into the retrograde system. By refining the rendezvous technique, we propose DDR (deep dive rendezvous) as a streamlined and effective alternative to conventional externalization. This technique has the potential to reduce risks of procedural complications, preserve collateral vessel integrity, and diminish the need for additional equipment or introduction of complex procedural steps. In conclusion, the versatility of this technique extends to serving as both a primary strategy and a bailout solution, making it a valuable option in cases where conventional externalization is either impractical or unsafe during the retrograde Chronic total occlusion percutaneous coronary intervention (CTO-PCI).

Aiming to realize the aerial rendezvous of multi-unmanned aerial vehicles (UAVs) with a carrier, this work proposes a rendezvous guidance and formation control (RGFC) scheme for UAVs. First, according to three-dimensional relative kinematics between the leader in UAVs and the aerial rendezvous point (ARP) behind the carrier, a predefined-time sliding-mode rendezvous guidance method is designed under terminal line-of-sight (LOS) angle and velocity constraints. Then, a predefined-time event-triggered consensus (PTETC) control method for the followers in UAVs is proposed to realize multi-UAV formation control with lower communication consumption. By applying fundamental filtering techniques to the available system states and invariant manifolds, an unknown system dynamics estimator (USDE) is designed to estimate the unknown disturbances. On this basis, a USDE-based UAV backstepping control structure is developed for UAVs to track guidance commands within a predefined time. Furthermore, the stability of the closed-loop system is proved by using a Lyapunov function, and Zeno behavior under PTETC is excluded. Finally, numerical simulations validate the effectiveness of the proposed RGFC scheme.

This paper proposes a novel approach to solving the time-optimal rendezvous problem for spacecraft in orbit. Initially, the characteristics of the time-optimal rendezvous solution in the in-plane motion of the relative equations of motion are analyzed using the direct collocation method. A time-delay filter is designed in the frequency domain using the analysis results. And then, it transforms the time-optimal control problem into a parameter optimization problem. By solving this optimization problem, the switching times of the bang–bang control profile can be determined. The effectiveness of the proposed method is examined through various simulations, demonstrating its ability to resolve the discontinuities caused by the bang–bang control profile while also being effectively applicable under various boundary conditions. Additionally, the proposed method turns out to be robust against disturbances through real-time application.

This paper details the design of a guidance architecture, in the form of a layered, finite state machine, meant to enable safe and autonomous rendezvous operations. The onboard software uses relative state parametrization based on relative orbital elements which provide significant geometrical insight into the shape of the relative orbit. The development is structured in two main steps: first, novel closed-form impulsive control schemes, derived from the Gauss Variational Equations expressed in a velocity-aligned frame, are formulated. These complement available strategies from the literature and generalize them for arbitrarily eccentric reference orbits. Secondly, the definition of the guidance layer provides the chaser spacecraft with the capability to select, schedule, and execute the proper maneuvers to complete a given rendezvous scenario, ensuring operational safety and predictability. The functionality and performance of the implemented architecture are analyzed through numerical tests in a linear propagator and a high-fidelity non-linear simulator. The results provide validation of the developed maneuvers’ strategies, as well as demonstrating how the proposed guidance architecture can be used in a straightforward fashion across different target orbit scenarios, while guaranteeing the same level of passive safety.

The route fusion rendezvous strategy is mostly used for air refueling within the safety zone, with fewer restrictions on the rendezvous airspace. There are fewer restrictions on the combined airspace. The refueling aircraft follows a set route, and the UAV gradually converges with the refueling aircraft by adjusting its own course. The UAVs gradually merge with the fueler’s route until they track the fueler to a certain distance behind the fueler and synchronize with the fueler’s status. The subsequent docking process is carried out. The fused route design is analogous to the use of missiles to track and strike moving targets. The unmanned aircraft are treated as pursuers moving at high speed. The fueling aircraft are treated as targets moving in a fixed pattern to be returned. The main objective of the convergent route design is to draw on and select appropriate guidance laws to bring the unmanned aircraft close to the fuel tanker. The main objective of the route fusion design is to use and select a suitable guidance law that allows unmanned aircraft to approach the fueling aircraft and achieve autonomous rendezvous. The traditional navigation laws are Pure Pursuit (PP) and Proportional Navigation (PP). The basic idea is to change the speed vector of a drone by varying its size. The difference is that the pure tracking guidance law requires the speed vector of the drone to coincide with the line of sight. In contrast, the example guidance law starts from the fact that the angular rate of rotation of the drone’s speed vector and the ratio guiding law is to keep the angular rate of rotation of the speed vector of the drone and that of the target in a fixed proportion.

This paper addresses the design, analysis, and validation of safe close-proximity operations around uncooperative targets, with an application to the ClearSpace-1 (CS-1) mission. It is focused on the areas of Guidance, Navigation, and Control (GNC), and Mission Analysis, due to their criticality for the success and safety of this kind of operation. The relevance of the concepts, of the GNC solutions, and their validation is demonstrated for the case study of CS-1, a reference mission for the rendezvous, capture, and de-orbiting of an uncooperative target (i.e., the VESPA payload adapter). It is shown how the design approach can be adopted for the Concept of Operations of CS-1, covering the definition of keep-out zones, corridors, and GO/NO GO criteria, for assessing the passive safety of trajectories, and for the incorporation of active safety strategies. The analysis is adopted for functional chains such as the Navigation and Control, and the combination of a prototyping and a high-fidelity simulator is adopted for directed Model-in-the-Loop Monte-Carlo campaigns. The outcomes are intended to support the industry in the development of Close-Proximity Operations similar to that of CS-1. These can be adopted in a wide variety of missions, including Active Debris Removal and In-Orbit Servicing. In particular, the adopted concepts are a key contribution to the standardization of Close-Proximity Operations for non-cooperative rendezvous missions, and act towards a sustainable and safe commercial application.

In order to realize the simulation of the damage effectiveness of air defense projectiles against air targets, this paper uses the C++ programming language to complete the development of ammunition air damage simulation model by constructing the ammunition combat model and target vulnerability digital model, and designs the visualization simulation software of ammunition air damage effectiveness based on the Unity 3D engine. The results show that the visualization and simulation software of ammunition damage effectiveness against air targets can calculate the damage effect of ammunition on air and visualize the results of missile rendezvous, combat guidance and air target damage, which provides reference for the design of air defense ammunition introduction.

Intelligent and safe overtaking maneuvering is always a challenging task for autonomous vehicles. This paper proposes and experimentally implements a novel approach of overtaking maneuvering using modified form of Rendezvous Guidance (RG) algorithm for trajectory planning and obstacle avoidance, considering driver safety and comfort during autonomous overtaking. The simulations for all possible scenarios are conducted to ensure the effectiveness of proposed modified RG algorithm. These scenarios involved presence and absence of obstacle vehicle in overtaking lane alongside leading vehicle in driving lane. In addition, the enhanced performance of modified RG algorithm is established over conventional RG algorithm by comparative analysis. The results indicate that overtaking maneuvering period could be decreased by 10% using a modified RG algorithm and vehicle will cover less distance to complete overtaking. The efficacy of proposed method is justified by performing experiments using mobile robots. The experimental results and simulation results of modified RG algorithm are compared, and their plots are almost identical.