Rope Length Research Articles

A geometric model with stochastic error for abnormal motion detection of portal crane bucket grab

Abnormal swing angle detection of bucket grabs is crucial for efficient harbor operations. In this study, we develop a practically convenient swing angle detection method for crane operation, requiring only a single standard surveillance camera at the fly-jib head, without the need for sophisticated sensors or markers on the payload. Specifically, our algorithm takes the video images from the camera as input. Next, a fine-tuned ‘the fifth version of the You Only Look Once algorithm’ (YOLOv5) model is used to automatically detect the position of the bucket grab on the image plane. Subsequently, a novel geometric model is constructed, which takes the pixel position of the bucket grab, the steel rope length provided by the Programmable Logic Controller (PLC) system, and the optical lens information of the camera into consideration. The key parameters of this geometric model are statistically estimated by a novel iterative algorithm. Once the key parameters are estimated, the algorithm can automatically detect swing angles from video streams. Being analytically simple, the computation of our algorithm is fast, as it takes about 0.01 s to process one single image generated by the surveillance camera. Therefore, we are able to obtain an accurate and fast estimation of the swing angle of an operating crane in real-time applications. Simulation studies are conducted to validate the model and algorithm. Real video examples from Qingdao Seaport under various weather conditions are analyzed to demonstrate its practical performance.

დატვირთული ბაგირის სტატიკური წონასწორული მდგომარეობის გაანგარიშება საწყის მონაცემთა მიმდევრობითი ვარიაციის გზით დრეკადი წაგრძელების გათვალისწინებით

The article discusses the task of implementing a discrete method for calculating the static equilibrium of suspended ropes in the modern programming language MS Visual Basic. A discrete general rope loading scheme for a rope suspended in a gravity field is proposed.Unlike analytical methods, it is possible to realize any number and direction load vector acting on the rope.The assignment and solution of the task can be given on the basis of the initial data given in the form of the length of the installation rope or the maximum tension of the rope.

The Hydrodynamic Similarity between Different Power Levels and a Dynamic Analysis of Ocean Current Energy Converter–Platform Systems with a Novel Pulley–Traction Rope Design for Irregular Typhoon Waves and Currents

In the future, the power of a commercial ocean current energy convertor will be able to reach the MW class, and its corresponding mooring rope tension will be very good. However, the power of convertors currently being researched is still at the KW class, which can bear less rope tension. The main mooring rope usually has a single cable and a single foundation. To investigate the dynamic response and rope tension of an MW-class ocean current generator mooring system, here, a similarity rule is proposed for (1) coefficients without any fluid–structure interaction (FSI) using the Buckingham theorem and (2) ones with FSI. The overall hydrodynamic drag and moment including the hydrodynamic coefficients in these two situations are represented in a Taylor series. Assuming similarity between the commercial MW-class and KW-class ocean current convertors, all hydrodynamic parameters of the MW-class system are estimated based on the known KW-class parameters and based on the similarity formula. In order to overcome the extreme tension of the MW-class system and to provide good stability, in this paper, we propose a pulley–rope design to replace the traditional single-traction-rope design. The static and dynamic mathematical models of this mooring system subjected to the impact of typhoon waves and currents are proposed, and analytical solutions are obtained. We find that the pulley–rope design can significantly reduce the dynamic rope tensions of the mooring system. The effect of the length ratio of the main traction rope, rope A, to the seabed depth on the dynamic tension of stabilizing converter rope D is significant. The length ratio is within a safe range, and the maximum rope dynamic tension is less than the fracture strength. In addition, if the rope length ratio is over the critical value, the larger the ratio, the higher the safety factor of the rope. In summary, the pulley–rope design can be safely used in an MW-level ocean current generator system.

Observer-based proportional-retarded controller for payload swing attenuation of 2D-crane systems including load hoisting-lowering

Crane systems are essential systems utilized in industry and for research. Nevertheless, they are always affected by endogenous and exogenous disturbances, which may generate undesirable payload oscillations, compromising people’s security and the system itself. Thus, to deal with these issues and control these mechatronic systems efficiently, this manuscript develops a novel robust observer-based proportional-retarded controller for perturbed two-dimensional cranes, considering variation in the rope length. This novel scheme makes the trolley follow a desired reference signal while reducing the payload variations. The controller structure allows for compensating disturbances, while a new control approach introduces artificial delays that stabilize the closed-loop system and attain the desired control objective. A formal theoretical analysis demonstrates the validity of the new proposal. Then, experimental results show the outstanding performance of the proposed control scheme and its superior performance against other methodologies from the literature.

Length matters: Effects of fishing gear and fishing behavior on the catch efficiency of demersal seines

Raiding seals pose a big problem to gillnet fishers in areas with high seal abundances. As moving to active gears could be a potential solution for that problem, one gear of particular interest in areas with relatively flat sea bed structure is the so-called “MiniSeine” – a demersal seine that is reduced in size so it can be operated from small vessels. Besides its ability to catch most of the species targeted by gillnet fishers, it offers various advantages compared to other active gears. To reduce the gear in size to fit on a small vessel, the present study assessed how seine rope length (4 coils vs 8 coils), seine rope diameter (18 mm vs. 22 mm) and seine net configurations of different sizes and shapes (three different designs) affect the catch efficiency and the ratio of fish below minimum conservation reference size (MCRS). In general, shorter seine ropes (4 coils) resulted in significantly lower catches than longer ones (8 coils), except for the smallest seine configuration. Larger seine net configurations and longer seine ropes caught generally less fish below MCRS, both up to around 10 %. The seine rope diameter did not affect catches significantly. As potential “adjusting screw” to counteract lower catches due to shorter seine ropes, the effect of different layout patterns of the seine ropes on the catch efficiency was assessed. Laying out the second seine rope perpendicular to the first one can increase the fishing area to more than three times while CPUE showed a tendency to be increased compared to the standard layout pattern. Besides its importance for a successful development of the MiniSeine, these findings are of equal interest for the large-scale demersal seine fishery.

Finite-Time Neural Network-Based Hierarchical Sliding Mode Antiswing Control for Underactuated Dual Ship-Mounted Cranes With Unmatched Sea Wave Disturbances Suppression.

As typical mechanical transportation equipment, cooperative dual ship-mounted cranes are widely used to transport large goods or containers in the marine environment. However, the control problem of the dual ship-mounted crane system is much more complex due to its underactuated characteristic and persistent unmatched disturbances. To solve these problems, we propose a novel neural network (NN)-based hierarchical sliding mode adaptive (HSMA) control method in this article. More specifically, an appropriate hierarchical sliding mode surface is first designed to connect the actuated and underactuated system state variables effectively. At the same time, the NNs are constructed to compensate for the unmatched interference of ship motions induced by sea waves simultaneously. Not only can the booms and the rope lengths reach their desired positions in finite time, but also the synchronous swing angles of the payload can be effectively eliminated. The asymptotic convergence of the closed-loop system's equilibrium points is achieved through rigorous mathematical proofs. Furthermore, the stability of each sliding mode surface is also analyzed utilizing the Lyapunov technique and Barbalat's lemma. Finally, numerous groups of compared numerical simulation results are investigated to further show the effectiveness and strong robustness of the proposed NN-based HSMA controller.

Technical review of encircling ringed gillnet for gillnet standardization in Indonesia

Abstract A technical review of encircling ringed gill nets for gillnet standardization in Indonesia is necessary to determine the design and construction by the waters and their fish target. The aim of this study was to describe the characteristics and design of fishing gear, including dimension, shape, and construction. The result of the identification of encircling ringed gillnet belonging to the local fishermen associated with the size of black pomfret (Parastromateus niger) as the fished target is used for the preparation of fishing gear standardization materials for the concerned by adjusting the size of fish target by measuring a fish length of about 150 up to 250 mm or a fish body circumference of about 300 up to 400 mm. As a result, the encircling ringed gillnet is made of nylon monofilament diameter 0.35 mm, and PE 380 d/6 mesh size 76,2 mm, ML = 2879 mesh, and MD = 218 mesh with an upper rope length of 120.65 m shorter than the lower rope 142,6 m. This Gillnet has a buoyancy of 173.6 grf/m and a sinking power of 124,7 grf/m or a buoyancy ratio of 1,39 sinking power. The gillnet is trapezoidal-shaped, operated by making the circumference of the net to fish closed around FAD (Fish Aggregating Device) near waters of more than 20 m depth with an attached net height of 13,30 m.

Design and Self-Calibration Method of a Rope-Driven Cleaning Robot for Complex Glass Curtain Walls

Rope-driven robots are increasingly used to safely and efficiently clean complex glass curtain walls. However, continuous global cleaning is difficult for most robots because of their poor performance in overcoming obstacles and adapting to curved surfaces, and an inconvenient winch calibration on complex surfaces further burdens such work. This paper presents a 3-DOF rope-driven robot and a winch self-calibration method for efficient cleaning. The robot, by integrating a 5-rope parallel configuration, a self-adaptive cleaning body, and a self-compensating driving winch, is designed to perform continuous, compliant, and accurate spatial motion on curved walls with obstacles. By deducing the kinematic model, the constraint relationship related to orderly arranged winch positions, maneuverable body positions, and accessible rope lengths is established during the robot tracking 3D trajectory. Combining the established relationship, a series of regulations are formulated for easily acquiring body positions and rope lengths, and then a self-calibration method is proposed by accurately calculating winch positions without using professional instruments. Experimental results show that the robot can perform global and precise movement on complex glass surfaces. Applying the proposed method, the maximum winch calibration error is 6.6 mm, and the maximum body tracking error is controlled within 9.6 mm.

The performance of anchovy purse seine in the North Coastal Java Sea, Indonesia

Small pelagic fishes including anchovies in Indonesia are caught by using different types of fishing gears. However, the anchovy purse seine commonly used polyethylene (PE) as material webbing which is less effective in the North Coastal Java Sea. This study aims to describe the design and construction of the anchovy purse seine and the characteristics of this gear construction. The research was carried out in the North Coastal Java Sea of Indonesia between May and June 2021. The main data from the nine anchovy purse seine units were collected using purposive sampling. The sampling method was performed by identifying and measuring the components of the number of anchovy purse seiners. The ratio of the length of the head rope to the length of the ground rope is between 0.926 and 0.991, so the net is not exactly rectangular, but almost trapezium in shape. The anchovy purse seine was constructed using webbing polyamide (PA) with 8 mm–9 mm in mesh size, which is considered a small mesh size. It is assembled with some ropes, floats, and sinkers. The anchovy purse seine is characterized by the dominant buoyancy value, 48 % larger than the sinking force. The sinking speed is 0.15 m/s, and the sinking time is 164 s. The anchovy purse seine's design and construction are suitable for operating in the waters of North Coast of Java.

An Enhanced Energy Coupling-Based Control Method for Quadrotor UAV Suspended Payload with Variable Rope Length

An Enhanced Energy Coupling-Based Control Method for Quadrotor UAV Suspended Payload with Variable Rope Length

Boosting efficiency of mussel spat collection for ecological sustainability: Identifying critical drivers and informing management

Abstract The long‐term sustainability of natural and bottom‐cultured mussel beds relies on the availability of spat (i.e. juvenile mussels). Traditional spat collection methods, which disrupt the donor population and its habitat, have prompted the adoption of suspended mussel spat collectors (SMCs) as an ecologically sustainable alternative. However, practical experience has demonstrated that SMC efficiency is subject to significant spatiotemporal variability, with the underlying biotic and abiotic drivers remaining unresolved. Based on 11‐year SMC practices in the Dutch Wadden Sea, we first validated, through field experiments, the inference that larval abundance and settlement rate in seawater are the primary determinants of SMC efficiency. Secondly, we screened the key factors driving variation in SMC efficiency using an integrated dataset that includes both management options (i.e. user‐defined factors, like SMC types) and environmental conditions (i.e. site‐specific factors, such as hydrodynamics). Lastly, we developed a predictive model to explore the sensitivity of SMC efficiency to these key factors. The efficiency of SMCs was not affected by larval abundance and settlement rate, but rather regulated by management options and environmental conditions, with the key factors identified as SMC type, substrate size, mean wave height and starfish abundance. Rope‐based SMCs outperform net‐based SMCs in terms of harvest efficiency. Both types of SMCs exhibit consistent sensitivity to environmental conditions, with harvest efficiency higher in areas with lower mean wave height and fewer starfish. Increasing substrate size (i.e. rope length and net area) in these areas has the potential to further improve SMC efficiency. Synthesis and applications: Our study highlights the importance of environmental conditions over life cycle‐related factors in regulating SMC efficiency. This offers optimistic prospects for investment in larger‐scale deployment of SMCs and maximizing efficiency through site suitability assessments beforehand. The predictive model we developed can provide information for this purpose. Furthermore, strategically adjusting management options would further optimize SMC efficiency, but it is necessary to balance the associated benefits and costs. Overall, our study underscores the predictability and controllability of SMC efficiency and informs management to maximize sustainable spat supply in both mussel culture and restoration.

Anti-swing control of varying rope length tower crane based on adaptive neural network sliding mode

Due to its complex nonlinear, underdriven, and strongly coupled characteristics, the tower crane will cause the load to swing violently when working, which will cause the tower crane to tip over in serious cases, and there exists a huge safety hazard. In this article, a new artificial neural network sliding mode control method is designed for the control problems of tower crane lifting in position and load swing prevention, which has strong robustness to disturbances and unmodeled dynamics, and ensures that the tower crane lifting is accurately tracked in position and suppresses the load swing at the same time. First, a nonlinear dynamics model of a five-degree-of-freedom tower crane considering the actual working conditions is established. Aiming at the problem that it is difficult to effectively control the nonlinear model of the tower crane system, a new neural sliding mode controller and compensation controller are designed based on the sliding mode control theory and using radial basis function neural network. The neural sliding mode controller is used to approximate the sliding mode equivalent controller with uncertainty and strong nonlinearity, and the compensation controller realizes the compensation of the neural sliding mode controller for the difference between the system control inputs and the uncertainty of the system. The convergence and stability of the proposed control system is rigorously demonstrated using the Lyapunov stability theory. Simulation studies have been carried out to verify the correctness of the model established in this article, as well as the excellent control performance of the control system and the ability to deal with system uncertainty, proving its strong robustness.

Test and analysis of walnut (Juglans regia L.) tree vibration transfer based on a low-frequency shaking table

Clarifying the low-frequency vibration transfer law of fruit trees is an important prerequisite for studying the intelligent harvesting operation of a low-frequency shaker. Through a vibration transmission test involving vibration parameters, tree parameters, and proportional acceleration, this study found that vibration frequency, amplitude, pre-tension, and rope length were the most significant influencing factors of proportional acceleration. Among them, amplitude and pre-tension have positive effects on proportional acceleration, vibration frequency and rope length have negative effects on proportional acceleration, and the interaction between amplitude and vibration frequency has significant effects on proportional acceleration. The proportional acceleration has a maximum response of 8.12 m/s2 when the vibration frequency is 6.86 Hz, the amplitude is 64.92 mm, the pre-tension is 1007.02 N, and the rope length is 6 m. The results of the study can guide research on and development of a low-frequency intelligent shaking machine as well as its field operation.

Correlation of Water Quality Parameters on Growth Performance of Seaweed (Kappaphycus alvarezii Doty, 1986) Cultivated with Diagonal Method

Kappaphycus alvarezii seaweed is an exported commodity that has economic value and is a leading commodity in aquaculture. The present study aims to analyze the correlation between water quality parameters and the growth of Kappaphycus alvarezii seaweed using the diagonal method. A completely randomized design using three treatments and four replications was applied for the experimental design. The research was carried out from May to June 2023 in the waters of Angkue Village, Bone Regency, Indonesia. Treatment in this diagonal model was based on the length of the diagonal rope, namely 2.5 m (treatment 1), 3.5 m (treatment 2), and 4.5 m (treatment 3) of the water depth and seaweed maintained for 42 days at a water depth of five meters. The results showed that the absolute growth of seaweed was 17,537.0 g during the study, with an average of 5845.67 ± 359.34 g. In treatment 1, the absolute growth was 1368.55 ± 5.29 g; in treatment 2, it was 1467.83 ± 4.58 g; and in treatment 3, it was 1547.88 ± 1.24 g, with the highest growth rate and the lowest growth rate in the first week. Water quality parameters all contribute positively to seaweed growth, but those that contribute most strongly to seaweed growth are brightness, phosphate, nitrate, and salinity.

VIDEO TRACKING BASED GRAVITY ACCELERATION ANALYSIS ON PENDULUM SWING

VIDEO TRACKING BASED GRAVITY ACCELERATION ANALYSIS ON PENDULUM SWING

A novel payload swing control method based on active disturbance rejection control for 3D overhead crane systems with time-varying rope length

To effectively mitigate payload swing in three-dimensional (3D) overhead crane systems during hoisting/lowering operations, a novel payload swing control method based on active disturbance rejection control (ADRC) is proposed in this work. Through a nonlinear tracking differentiator (NTD) is improved to extract the differential signals from the reference trajectory, a nonlinear extended state observer (NESO) is designed to estimate the total disturbance in the crane systems, and a compensation controller, based on the sliding mode method and utilizing a composite signal, is developed to ensure stable actuation, accurate positioning, and swing elimination. The feasibility of this control method is validated by comparative simulation analysis.

Modeling and Numerical Computation of the Longitudinal Non-Linear Dynamics of High-Speed Elevators

High-speed elevator systems comprise numerous components, and vibration issues are prevalent. The evident non-linear behavior resulting from changes in the wire rope length adds complexity to the investigation of elevator dynamics issues. This paper investigates dynamics modeling and numerical solution methods for longitudinal vibrations in a typical high-speed elevator system. The primary contributions of this paper include constructing a dynamics model for high-speed elevators using a substructure dynamics modeling approach. This model incorporates Newton’s law and the Lagrange equation to comprehensively represent the dynamics of the elevator car, car frame, traction system, and tension system. Additionally, a non-linear dynamics model of the steel wire rope is developed using the centralized mass method. This paper also presents an algorithm to solve the time-domain dynamics based on the variable-step-length Runge–Kutta method. Furthermore, it investigates the non-linear dynamics of elevators considering variations in the elevator’s intrinsic frequency and different elevator control strategies, focusing on the response characteristics of high-speed elevator dynamics. The findings of this thesis hold significant importance in the field of high-speed elevator dynamics. They aid in the design and debugging of high-speed elevator systems and serve as a foundation for future research into the non-linear aspects of elevators.

Experimental study on the course stability of a towed barge model

The course instability problem of towed objects is discussed in the paper. It is noted that many non-selfpropelled vessels do not have directional stability, as a result of which they make oscillatory movements relative to the course of the towing ship. Increased yaw rate leads to a decrease in towing speed, an increase in loads on the elements of the towing device and a significant increase in the width of the running lane. These factors can lead to an emergency and significantly complicate the towing process, especially on inland waterways. Two main ways to increase directional stability are considered. These are towing “on V-line”, that is a system in which the towing rope is divided into two parts and attached to two points of the towed barge, located symmetrically relative to the centerline, and the installation of skegs in the stern. To determine the effect of these methods, tests of a model of the mixed riversea navigation oil barge 2731 are carried out in calm deep water conditions in the experimental tank of the Admiral Makarov State University of Maritime and Inland Shipping. The root end of the towing rope is attached to the pylon of the towing tank trolley and, thus, the reverse influence of the barge on the characteristics of the tug movement is not taken into account. Sixteen options are considered. The half-width of the running lane is taken as a criterion for the stability of barge movement. As follows from the test results, with increasing towing speed and towing rope length, the width of the running lane increases slightly. The installation of end washers on the skegs has no effect on the stability of the barge. To reduce the width of the running lane occupied by the barge, it is recommended to use towing “on the V-line” and use skegs with fixed flaps.

Enhanced Trajectory Tracking of 3D Overhead Crane Using Adaptive Sliding-Mode Control and Particle Swarm Optimization

Cranes hold a prominent position as one of the most extensively employed systems across global industries. Given their critical role in various sectors, a comprehensive examination was necessary to enhance their operational efficiency, performance, and facilitate the control of transporting loads. Furthermore, due to the complexities involved in disassembling and reinstalling cranes, as well as the challenges associated with precisely determining system parameters, it became essential to implement adaptive control methods capable of efficiently managing the system with minimal resource requirements. This work proposes a trajectory tracking control using adaptive sliding-mode control (SMC) with particle swarm optimization (PSO) to control the position and rope length of a 3D overhead crane system with unknown parameters. The PSO is mainly used to identify the model and estimate the uncertain parameters. Then, sliding-mode control is adapted using the PSO algorithm to minimize the tracking error and ensure robustness against model uncertainties. A model of the systems is derived assuming changing rope length. The model is nonlinear of second order with five states, three actuated states: position x and y, and rope length l, and two unactuated states, which are the rope angles θx and θy. The system has uncertain parameters, which are the system’s masses Mx, My and Mz, and viscous damping coefficients Dx, Dy and Dy. A simulation study is established to illustrate the influence and robustness of the developed controller and it can enhance the tracking trajectory under different scenarios to test the scheme.

Pengaruh kemiringan pada bagian sayap terhadap kelajuan tenggelam tali pemberat alat tangkap pukat cincin

Purse seine is a tool (gear) used to catch pelagic fish that form a swarm. As with other fishing gear, a purse seine unit consists of a net, a boat, and auxiliary equipment (rollers, lights, echosounders, and so on). Purse seine is a fishing gear classified in the surrounding net group. Purse seine is also known as a ring trawl because it is equipped with a ring that is used as a place to attach the coloring rope which is very important during the operation of the net. Because the net that was originally bagless will form a pocket at the end of the capture operation. The ring trawl itself has a different name in each region in Indonesia, in North Sulawesi it is known as soma pajeko. There are three technical factors that need to be considered for the success of ring trawl fishing, namely: (1) circular speed, (2) speed and depth of sinking ballast rope, and (3) speed of pulling the choir ropeThe speed of sinking is largely determined by the ballast, the type of material, the size of the thread and the size of the net bit, as well as the ratio of the length of the float rope and the ballast rope. The sinking speed of the ballast rope is calculated based on the relationship between the depth and the sinking time of the ballast rope needed. The speed of the ballast can be increased by increasing the weight of the ballast, but it must be considered because it will increase the tension of the net. Ballast weight per meter ballast ropeBut it should be considered because it will add tension to the net. Greater ballast weight per meter ballast rope will add greater sinking speed. The method used in this study is an experimental method, which is a study that looks for the influence of certain variables on other variables under tightly controlled conditions. The analysis in this study consisted of 4 net models with different slope percentages, namely 57%, 75%, 100% and 125% slopes. The results of the analysis showed that the more tilted the wing with a slope of 57%, 75% and 100%, the more the sinking rate of the ballast rope but for a slope of 125% it does not contribute to the speed of sinking 57% slope at a depth of 5.5 meters the required time is 16.37 seconds, 75% slope at a depth of 5.5 meters is 15.16 seconds, 100% slope at a depth of 5.5 meters the time required is 19.84 seconds and 125% slope the time required at a depth of 5.5 meters is 19.88 seconds. The best sinking speed of the four net models that have been made based on existing data is at 75% slope.