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Towing cable arrays have made significant contributions across various fields, and their outspread process is crucial for realizing their functionalities. However, research on the dynamic characterization of the outspread process of towed cable arrays lacks systematic organization. This paper reviews, organizes, and analyzes the outspread process of towing cable arrays, drawing on relevant models, case studies, and structural features. It ingeniously applies concepts from parachute outspread to the analysis of towing-cable-array deployment. The study systematically examines the deployment of towing cable arrays under varying cable lengths, wave conditions, and the interactions between line arrays. The goal is to integrate existing research on the outspread of towing cable arrays, addressing the gaps in the description of this process and providing a comprehensive analysis of the outspread characteristics under different conditions. Additionally, this paper identifies current limitations in this area and provides insights for future developments. Furthermore, it explores the potential application of AI to address these challenges. The aim of this paper is to contribute meaningfully to this field. [ABSTRACT FROM AUTHOR]

When the landing position of a shipborne helicopter on the deck does not meet the requirements for towing it into the hangar, its position must first be corrected before towing can proceed. This paper studied the methods for using Shipborne Rapid Carrier Robots (SRCRs) to correct helicopter positions on the deck and proposed two correction methods, the stepwise correction method and the continuous correction method, aiming to improve the efficiency of the position adjustment process. Firstly, the actual helicopter landing position deviation was divided into two components—lateral offset and fuselage yaw angle—to quantitatively assess the deviations. Then, a mathematical model of the SRCR traction system was established, and its traction motion characteristics were analyzed. The kinematic characteristics and control processes of the two proposed position correction methods were subsequently studied, revealing the coordinated control relationships between key control elements. Finally, simulations were conducted to validate the feasibility of the proposed correction methods and compare their efficiencies. The results indicated that both the stepwise and continuous correction methods effectively achieved the position correction objectives. The stepwise method was more efficient when the initial yaw angle was small, while the continuous method proved more efficient when the initial yaw angle was large and the lateral offset was minimal. The results of this study may provide a valuable reference for correcting the positions of helicopters on deck. [ABSTRACT FROM AUTHOR]

Maneuver simulation of a standard ship model gives indication of numerical accuracy. In the numerical calculation of ship maneuvering, uncertainty analysis is a necessary step to ensure the accuracy of the calculation. In this study, uncertainty pair analysis is carried out in the simulation of the turning circle motion of the standard ship model ONRT in waves. According to the uncertainty analysis procedure recommended by the International Towing Tank Conference (ITTC), the change of ship resistance caused by the number of grids is studied to determine the influence of grid density on the numerical prediction. The simulation of turning motion in waves is carried out based on the uncertainty analysis. It is found that the minimum number of overset grids for this simulation is 1.4 million. The numerical results are fairly accurate compared to experimental results, and this technique provides a method with low calculated cost for this simulation. [ABSTRACT FROM AUTHOR]

Currently, cranes used at sea are insufficient in efficiency. Accordingly, a floating multi-robot coordinated towing system is proposed to meet offshore towing needs. However, the towing robot is prone to overturning because of the system's utilization of rope-driven robot flexibility and its floating attributes in fluid environments. First, the kinematics and dynamics of the towing system are analyzed through coordinate transformations and hydrodynamic theory. Subsequently, physical modeling of the towing system is conducted, with an emphasis on analyzing the system's fluid-structure coupling properties, supplemented by illustrative examples. Finally, the stability of the floating robot is assessed based on ship stability theory, encompassing analyses of the rope tension effects, size and shape of the floating base, and external environmental factors influencing system stability. Results show that the special shape of the floating base is beneficial in reducing water resistance and improving the stability of the floating robot in the flow field. The results provide a good basis for the system structural design and application. [ABSTRACT FROM AUTHOR]

In the field of civil aviation, the nose landing gear is a critical component that is prone to damage during taxiing. With the advent of new technologies such as towing taxi-out and hub motors, the nose landing gear faces increasingly complex operational environments, thereby imposing higher performance demands. Ensuring the structural safety of the nose landing gear is fundamental for the successful application of these technologies. However, current research on aircraft nose landing gear under these new conditions is somewhat lacking, particularly in terms of reliable analysis models for real-world scenarios. This study focuses on a typical Class C aircraft, specifically the B-727 model, for which a finite element model of the nose landing gear is developed. Modal testing of the aircraft's nose landing gear is conducted using the impact hammer method, and the results are compared with those from the simulations. The experimental data indicate that the error range for the first seven natural frequencies is between 0.23% and 9.27%, confirming the high accuracy of the developed landing gear model. Furthermore, with towing taxi-out as the primary scenario, a dynamic model of the aircraft towing system is established, and an analysis on the structural strength and topological optimization of the nose landing gear under various conditions, including high speeds and heavy loads, is performed. The results show that the developed model can effectively support the analysis and prediction of the mechanical behavior of the nose landing gear. Under high-speed, heavy-load conditions, the nose landing gear experiences significantly increased loads, with the maximum deformation primarily occurring at the lower section of the shock strut's outer cylinder. However, no damage occurred. Additionally, under these conditions, an optimized structural design for the landing gear was identified, which, while ensuring structural strength, achieves a 22.32% reduction in the mass of the outer cylinder, also ensuring safety in towing taxi-out conditions. [ABSTRACT FROM AUTHOR]

Positioning technology is one of the key steps of automatic docking. At present, vehicle docking technology is widely used in airport baggage cars, towing trailers and other fields, and the docking process is mostly done manually. In order to realize the automatic docking of vehicles in mixed scenes, this paper proposes a fast positioning method for docking vehicles in mixed traffic scenes. First, using the regression relationship between the template size in the camera's field of view and the actual distance, FFT template matching and threshold judgment methods are employed to locate, track, and match the template, as well as verify the threshold results, in order to achieve template long-distance positioning and ROI extraction. Then, based on the regression relationship between AprilTag pixels in the camera's field of view and actual distance, the experiment of AprilTag minimum recognition pixel is designed. Finally, the real-time pixels of AprilTag are calculated from the real-time ranging results, and compared with the minimum recognition pixel of AprilTag, it is judged whether the recognition conditions are met, so as to carry out the subsequent AprilTag positioning. The experimental results demonstrate that the method proposed in this paper can achieve rapid and accurate positioning of a target docking vehicle at a long distance, while reducing the mismatch rate. On this basis, by designing the identification conditions of AprilTag, the rapid identification and positioning of AprilTag is realized, which reduces the traversal time of the algorithm. The feasibility of this positioning method is verified by the attitude angle error experiment, which provides supporting conditions for the subsequent docking path planning and vehicle control. [ABSTRACT FROM AUTHOR]

The offshore wind sector is moving into deep waters and using floating platforms to harness the higher wind speeds in exposed locations. There are various floating platform types currently in development, but semi-submersibles are considered the most prominent early movers. Such floaters need to be towed to and from wind farm locations for installation, special cases of repair and decommissioning. As with any other offshore activity, metocean limits exist for towing operations which can impact the development of a wind farm. It is important to calculate the motion and loads of the platform before commencing the towing operations and to check whether they exceed the defined limits to enable safe execution. In this paper, two approaches using two different numerical tools to predict the motion of a fully assembled floating wind platform under tow are presented and compared. A potential flow-based method derived from a low forward speed approach and a hybrid approach combining potential flow and Morison equation methods are investigated, and the numerical predictions are compared and validated against experimental results. Both methods demonstrate accurate predictions, depending on the wave condition and towing speed, albeit differing in execution time and the simplicity of the simulation setup. The first method was found to provide good predictions of the motion in low-speed (0.514–1.543 m/s) towing conditions. The second method provides better results for all the towing speeds and wave heights. As the wave height and towing speed increase, deviations from experiments were observed, signifying non-linear phenomena that are difficult to analyse using the mentioned potential-flow-based methods. [ABSTRACT FROM AUTHOR]

The aviation industry has proposed multiple solutions to reduce fuel consumption, air pollution, and noise at airports, one of which involves deploying electric trucks for aircraft towing between the stand and the runway. However, the introduction of tow trucks results in increased surface traffic, posing challenges from the perspective of air traffic controllers (ATCOs). Various solutions involving automated planning and execution have been proposed, but many are constrained by their inability to manage multiple active runways simultaneously, and their failure to account for the tow truck battery state of charge during assignments. This paper presents a novel system for taxi operations that employs autonomous tow trucks to enhance ground operations and address deficiencies in existing approaches. The system focuses on identifying conflict-free solutions that minimise taxi-related delays and route length while maximising the efficient use of the tow trucks. The algorithm operates at a strategic level and uses a centralised approach. It has the capacity to cater for multiple active runways and considers factors such as the tow truck battery state of charge and availability of charging stations. Furthermore, the proposed algorithm is capable of scheduling and routing tow trucks for aircraft taxiing without generating traffic conflicts. [ABSTRACT FROM AUTHOR]

A simulation approach relying on a single grid topology has been employed to replicate the motion characteristics of different experimental facilities, including towing tank, rotating arm mechanism, and planar motion mechanism using a single mesh. The control volume and computational mesh setup was built in a way to enable to perform both steady and time dependent simulations to compute entire set of coefficients required by the standard submarine equations of motion. Mesh is consisted of a rectangular prism shaped background and a spherical overset domain which can be rotated, circulated and oscillated depending on the simulation type. To enable the implementation of this approach to the rotating arm simulations, modifications to source code of the open-source computational fluid dynamics software OpenFOAM have been made. Motivation is to change the perspective on the problem by using the knowledge of mathematics behind the solution algorithms and the software structure. In this study extensive set of time-independent coefficients obtained via straight and oblique towing as well as steady rotation simulations are presented for a fully appended generic submarine geometry. Results are then compared with the benchmark experimental data. It is found that the consistency between results are quite satisfactory. [ABSTRACT FROM AUTHOR]

The present paper investigates the unexpected unstable failure observed commonly on fiber tows tensile-tested under strain-controlled loading, although the force on the fibers should theoretically be relaxed under controlled strain. A model of the reaction of the load train when the fibers break under strain-controlled conditions is proposed. The criterion for instability is based on the comparison of the filament strength gradient and the overstress induced by the reaction of the load train when the fibers fail. The contribution of multiplet filament failures attributed to the fiber inter-friction and stress waves was taken into account. The compliance of the load train for the test results considered in the present paper was measured. It is shown that, depending on the number of filaments sharing the overload, the values of the structural parameters, and the fiber characteristics, the condition of unstable failure may have been fulfilled by the SiC fiber tows that were tested in house, as discussed in the present paper. The critical parameters that were identified and quantified include the load train compliance, gauge length, fiber stiffness, and bonding of the tow ends. This should allow the proper conditions for stable failure. Important implications for the validity and an analysis of the strengths derived from the unstable fracture of the tows are discussed. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced plastic (CFRP) is a composite material with high specific strength and is applied to transportation and aviation equipment. However, conventional processing methods require large-scale production apparatus or a high level of dexterity that only comes with extensive experience which makes it difficult to achieve high processing efficiency. The objective of this study is to develop a novel method for forming thermos-plastic CFRP (CFRTP) preforms implementing a 3D printer for press molding. Applying this method offers the advantage that continuous carbon fibers can be formed on a free-form surface. It also reduces the manufacturing time and operator skill required. The goal of this research is to establish a method for molding a free-form surface composed of continuous fibers by employing a 3D-printed preform designed to match the unfolded polygonised diagram of the free-form surface. Previous research introduced an unfolding approach for converting a three-dimensional shape to a plane surface based on a computer-aided design and manufacturing (CAD/CAM) system, enabling the generation of an unfolding diagram that maintains the continuity of fiber tow. Furthermore, the validity of unfolded diagram was confirmed by reproducing the objective three-dimensional shape from the unfolded diagram using thermos-setting CPRP (CFRTS) tow prepreg. In this study, the viability of the proposed molding process using CFRTP preform fabricated by a 3D printer was verified and an assessment of the formability of the molded parts was conducted. [ABSTRACT FROM AUTHOR]

The authors have developed a method to estimate the catch efficiency of sampling gear using acoustic information. Since different sampling conditions will cause different sampling results, it is necessary to know more details about catch efficiency to quantitatively catch juvenile fish. In this study, we estimated the catch efficiency of a framed midwater trawl (FMT) for juvenile walleye pollock, and investigated differences in the catch efficiency of the FMT due to various influencing factors. To clarify the effects of different sampling conditions on catch efficiency, we investigated changes in catch efficiency by survey time (daytime and nighttime), net color (black and cyan), and towing speed (2 kt, 3 kt, 4 kt). It was quantitatively shown that the catch efficiency was higher at nighttime than during the daytime, the catch efficiency of black net was higher than that of cyan net, and the catch efficiency was higher at the faster towing speed. Comparing the estimated catch efficiency under different conditions, we found that survey time was the most important influencing factor. [ABSTRACT FROM AUTHOR]

Purpose: Drownings are a societal phenomenon occurring worldwide, hence the importance of rescue skills, including directly towing a victim to a safe place. The purpose of this study was to evaluate the most effective towing techniques based on kinematic parameters, considering different types of drowning cases, for their recommendation for widespread use in water rescue. Methods: The research involved 18 water lifeguards aged 18-25 years. The evaluation included speed tests in towing a mannequin over a distance of 50 m using the Extended Arm Tow (EAT), Double Armpit Tow (DAT), "Sailor" Technique Tow (STT) and with a rescue tube (RT), accompanied by video recording to measure in the designated measurement area the number of cyclic paddling movements by the lower limbs, angles of the body attack, towing velocity, and its decrease during towing. Results: Number of cyclic paddling movements by the lower limbs, towing with a RT was considered the most beneficial, and least beneficial was the DAT. In the DAT, the lifeguard swam with the smallest body angle, in contrast to the STT, where this angle was the largest. The effect of the number of cyclic paddling movements and the body angle by the lifeguard was the velocity, with the highest value recorded in towing using a RT; in other techniques, velocity were similar. Conclusions: Institutions associated with water rescue should recommend towing using a RT for direct rescue actions in the water, as its use shortens the time, while simultaneously increasing safety for both the rescuer and the victim. [ABSTRACT FROM AUTHOR]

The effective assessment of risk and speed limitations in ice are critical for the route planning of polar cruise ships. While the Polar Operational Limit Assessment Risk Indexing System (POLARIS) is widely used to evaluate the operational risk in ice, its scope of assessment is limited to the ship's assigned ice class. For a specific ship with a given ice class, the propulsion performance under varying ice conditions is more essential for assessing the besetting risk and finding an optimal route. To establish a more detailed risk evaluation method for a PC6 class polar cruise ship, propulsion performance under various ice conditions is obtained via model tests in an ice tank. During the tests, the tow force, propeller torque, and thrust are measured under different ship velocities and propeller rotation rates, and the relations between required delivered power (P) and ship velocity (V) under the tested ice thicknesses and concentrations are obtained and extended to other ice conditions by curve fitting. A new risk index outcome, RIO*, is proposed after POLARIS according to the optimized load ranges of the ship's rated power. Four risk levels, including low, medium, high, and unnavigable, are classified with the required propulsion power in ice being 50%, 85%, 100%, and >100% of the rated power, respectively. The recommended speed limit for each risk level is proposed based on the economical service speed of 11 kn, the operational limit of 3 kn by POLARIS and the minimum speed of 0.5 kn to avoid besetting, respectively. Based on the RIO* and P–V relations, the speed map for varying ice thicknesses and concentrations can be calculated. On these bases, a route planning simulation for the present polar cruise ship is performed. Results of the case study show that 29% of the simulated area is identified as "unnavigable" by the present procedure, while only 8% is detected by POLARIS. [ABSTRACT FROM AUTHOR]

The offshore wind sector is moving into deep waters and using floating platforms to harness the higher wind speeds in exposed locations. There are various floating platform types currently in development, but semi-submersibles are considered the most prominent early movers. Such floaters need to be towed to and from wind farm locations for installation, special cases of repair and decommissioning. As with any other offshore activity, metocean limits exist for towing operations which can impact the development of a wind farm. It is important to calculate the motion and loads of the platform before commencing the towing operations and to check whether they exceed the defined limits to enable safe execution. In this paper, two approaches using two different numerical tools to predict the motion of a fully assembled floating wind platform under tow are presented and compared. A potential flow-based method derived from a low forward speed approach and a hybrid approach combining potential flow and Morison equation methods are investigated, and the numerical predictions are compared and validated against experimental results. Both methods demonstrate accurate predictions, depending on the wave condition and towing speed, albeit differing in execution time and the simplicity of the simulation setup. The first method was found to provide good predictions of the motion in low-speed (0.514–1.543 m/s) towing conditions. The second method provides better results for all the towing speeds and wave heights. As the wave height and towing speed increase, deviations from experiments were observed, signifying non-linear phenomena that are difficult to analyse using the mentioned potential-flow-based methods.

The debris-tether-tug (DTT) system, has been considered as one of the most promising techniques for the space debris removal. In order to decrease the control difficulty of the DTT system, the DTT system was usually designed with a single tether. However, when the target owns the complex attitude motion, the removal efficiency of the classic DTT system (towing the target by a single tether) is limited. A modified DTT model with the hierarchical-tethered architecture is proposed to improve the removal efficiency in this paper. Based on the Hamiltonian variational principle, the coupling non-smooth dynamic model for the hierarchical-tethered towing system is established, in which, four tethers are divided into two groups to describe the asymmetry of the DTT model well. The symplectic Runge-Kutta method is employed to simulate the evolution of the orbit radius of the target, the length of the tethers, the position of the tethers' mass center and the target attitude angle. The numerical results reported show that, the competition relationship between the attitude stability of the target and the stability of the variation of the sub-tethers is affected by the relative stiffness of the tethers. In addition, the capture ability of the modified DTT system for the space target with a certain spinning speed is illustrated, which provides a theoretical basis for the design of the DTT system in future. [ABSTRACT FROM AUTHOR]

The mono-column composite bucket foundation has gained practical application in offshore wind power due to its advantages of simple fabrication, fast construction, and low cost. To ensure the safe and stable transportation of this structure to its designated sinking position, this study focuses on producing a scaled model of the mono-column composite bucket foundation. Through model testing, the floating characteristics of the structure during towing in regular waves are examined. The conclusion of the study is as follows: a significant towing force is required to provide the initial velocity of the structure. As the wave period and height increase, the structure necessitates a larger towing force, experiences greater pitch and heave responses, and exhibits more noticeable fluctuations in internal air pressure. The paper aims at providing practical engineering insights. [ABSTRACT FROM AUTHOR]

In recent years, the International Maritime Organization (IMO) has gradually introduced more stringent new Ship Energy Efficiency Design Index (EEDI) bills, and transport ships are more inclined to reduce the speed and increase the length and square coefficient to meet the design requirements. However, the size of the ship model that can be accommodated in the towing tank is seriously limited. Under the action of the scale effect, the accuracy of the prediction results of the resistance performance of large ships is particularly prominent. To break through the limitations of the test site, a large-scale ship model resistance towing test system and data analysis method in the port were established. By comparing with the results of small-scale model tests in the towing tank, the applicability of the 1957 ITTC friction line and Grigson friction line in the resistance prediction of the full-formed ship was analyzed, and the scale effects of resistance components were also examined. The results show that the scale effect of the form factor of full-formed ships is weak. The three-dimension method based on the empirical formula of mixed-form friction resistance of ITTC-Grigson is more suitable for predicting the resistance performance of full-formed ships. [ABSTRACT FROM AUTHOR]

One of the most crucial tasks for naval architects is computing the energy required to meet the ship's operational needs. When predicting a ship's energy requirements, a series of hull resistance tests on a scale model vessel is carried out in constant speed stages, while the acceleration stage measurements are ignored. Another important factor in seakeeping analysis is the ship's hydrodynamic added mass. The second law of dynamics states that all this valuable information, that is, the dependence of the hull resistance on the vessel's speed and the added mass, is accessible from just one acceleration stage towing test done up to the maximum speed. Therefore, the acceleration stage, often overlooked in traditional towing experiments, can be a valuable source of information. For this reason, this work aims to generalise Froude's scaling procedure to full-scale vessels for the accelerated stage towing tests. [ABSTRACT FROM AUTHOR]

A variety of mission equipment is mounted and utilized on UUVs (unmanned underwater vehicles) for the development of marine resources and underwater searching for military purposes. For exploration of a wide area, it is advantageous to use a towed underwater platform, and for precision exploration to a specific location, to use an active mobile ROV (remotely operated vehicles). Since the TUV (towed underwater vehicle) moves according to the speed of the towing vessel, it cannot be operated if the vessel is stationary or the speed is low. Therefore, TUVs do not have equipment that is useful at low speeds, such as optical cameras or forward looking sonars. If a TUV capable of active movement such as stationary or low-speed operation is developed, it can search a wide area and then accurately search for a specific location, with one platform mounting various mission equipment. In this paper, we propose a method for estimating the control model for a prototype of this novel TUV, and propose a depth and posture control algorithm to which the model is applied. The proposed TUV and control algorithm were verified by experiments under the flow rate environment in the circulating water channel. [ABSTRACT FROM AUTHOR]

The state of near-Earth space pollution is considered, including the dynamics of growth of this pollution. Presented current information on the launch of nano-satellites, which is an additional factor in the pollution of low earth orbit. On the basis of open information, the analysis of the development of Russian and foreign approaches to the most polluted orbits cleaning, including technological experiments with the use of various means of capture is carried out. For different capture devices the options of towing space debris objects to the disposal orbit are considered.

The traditional method of taxiing for civil aircraft, which relies on their engines, may be surpassed by the new method of towing taxi-out due to its superior advantages such as reduced energy consumption, lower emissions, and higher efficiency. However, the towing taxi-out system poses a challenge to lateral stability due to the concentration of mass at the rear, leading to severe instability when turning at high speeds. To address this issue, a nonlinear civil aircraft towing and taxiing system model and a linear four-degree-of-freedom civil aircraft towing and taxiing system reference model were established using TruckSim and Matlab/Simulink software. The fuzzy proportional–integral–derivative controller was utilized, with the braking torque of each wheel serving as the control variable and the real-time yaw rate difference and its rate of change as the fuzzy control input. The controller was compared and validated with a traditional PID controller. The results of the simulation showed that the fuzzy PID control has better nonlinear characteristics and stronger adaptability to operating conditions compared to traditional PID control, providing timely, effective, adaptive, and robust control effects for the vehicle dynamics model. Under the fuzzy PID control, the peak yaw speed of the civil aircraft decreased to 10 degrees per second under double-shift conditions, representing an increase of 23.1%. Furthermore, the lateral stability and safety of the towing taxi-out system were improved, as evidenced by the reduction in the yaw rate of the tractor and civil aircraft under the hook condition. The use of this controller provides valuable technical guidance and support for the practical development and safe application of the towed glide mode. [ABSTRACT FROM AUTHOR]

Collision avoidance is a priority task for ensuring the safety of a maritime transportation system. However, for a ship towing system, which is characterized by multiple vessels and physical connections, the research works about collision avoidance is limited. Thus, this paper proposes a speed and heading control-based conflict resolution of a ship towing system for collision avoidance. Two systems compose the core of the proposed conflict resolution: the risk assessment system and the coordination control system. The risk assessment is to identify the conflict and determine the time of avoiding action by calculating the index of conflict and the available maneuvering margin. The coordination control is based on the model predictive control (MPC) strategy to cooperatively control two tugboats for regulating the position, heading, and speed of the manipulated ship. Simulation experiments show that according to the index of conflict, the time cost, and the fuel consumption, a selected operation of combined heading and speed can be recommended for a ship towing system to provide a safer and more efficient towage manipulation. • Formulate the risk assessment criteria for a multi-vessel towing system. • Propose an MPC-based control method for a towing system to regulate multi-objectives. • Provide an optimal collision avoidance operation for a multi-vessel towing system. [ABSTRACT FROM AUTHOR]

It is necessary for robot-trailer to tow robot to the charging station for recharging when the robot fails, or the battery cannot support the robot to the charging station. However, the delay of towing robot is affecting the working efficiency of mobile robot. Based on the task priority of the mobile robot and impact degree on the room after the power failure, the paper proposes a distributed scheduling of robot being towed to recharge for reducing the delay expectation. This work designs a Distributed Three Nodes Service (DTNS) scheduling based on the communication between charging stations. The two-step path-planner based on decision factor and travel path is used in the scheme. Simulations show that the distributed scheduling of this work can well ensure the success communication in the case of low power, and DTNS can well reduce the delay expectation of towing robot to recharge. Compared with First Come First Service (FCFS) scheduling, DTNS reduces the towing delay by 48.71%, 48.83% and 40.45% when there are some robots sending the towing request, and by 58.77%, 39.97% and 41.90% when no robot sends request in the case of 1, 2 and 3 robot trailers in the service space respectively. [ABSTRACT FROM AUTHOR]

A new towing taxi-out departure mode has become the preferred choice to replace the traditional departure mode of civil aircraft due to its obvious advantages of low energy consumption, low emissions, and high efficiency. However, the inertia may lead to potential lateral instability and even "Jack-knifing", as the mass of the system is concentrated in the rear. In this paper, the lateral instability mechanism and influencing factors of the civil aircraft towing taxi-out system were studied using computer virtual simulation technology and taking Boeing 737–400 and AM210 tractors as research objects. The results show that the "Jack-knifing" phenomenon was caused by the lateral instability of the system when the sliding speed of the system was more than 15 km/h, and the system was accompanied by the lateral slip condition. Furthermore, the safety zone, side-show zone and jack-knifing zone of the system were defined in terms of towing speed and steering angle. Additionally, a towing safety zone was created under different airport track conditions by analyzing the lateral stability of the system. The conclusion of this study may provide a theoretical basis and reference for the safe application of the new taxi-out departure mode. [ABSTRACT FROM AUTHOR]

A tethered towing system provides an effective method for capturing pieces of space debris and dragging them out of orbit. This paper focuses on the in-plane stability analysis and libration control of a two-segment tethered towing system. The first segment is the same as the traditional single-tether towing system. The second segment is similar to a simplified space tether net. The dynamic equations are established in the orbit frame. Considering the elasticity of the tethers, the equilibrium solutions are obtained and the stability of equilibrium solutions is proved. An in-plane libration controller based on the sliding mode control scheme is designed to ensure the safety of the towing mission and save fuel. The controller suppressed the librations of the in-plane angles in the desired state by applying two external torques. Finally, simulation results are provided to validate the effectiveness of the proposed controller. [ABSTRACT FROM AUTHOR]