Cable Problem Research Articles

Towards Tethered Tool Manipulation Planning with the Help of a Tool Balancer

Handling and maneuvering tools across a robot workspace is a challenging task that often requires the implementation of constrained motion planning. In the case of wired or tethered tools, their maneuvering becomes considerably harder by the tool cable. If the cable presence is not considered, the robot motions may make the cable become entangled with the robot arms or elements of its workspace, causing accidents or unnecessary strain on the robot and the tool. Furthermore, the behavior of the tool cable during manipulation and its degree of entanglement around the robot are difficult to predict. The present paper introduces a constrained manipulation planner for dual-armed tethered tool manipulation involving tool re-grasping. Our solution employs a tool balancer to straighten the tool cable and facilitate the cable deformation problem. The planner predicts the cable states during manipulation and restricts the robot motions in order to avoid cable entanglements and collisions while performing tool re-posing tasks. Furthermore, the planner also applies orientational constraints to limit the cable bending, reducing the torque and stress suffered by the robot due to the cable tension. Simulations and real-world experiments validated the presented method.

Cooperative Transport of a Slung Load Using Load-Leading Control

A system for cooperative transport of a slung load by a team of autonomous rotorcraft is described. The method described here is hierarchical and centralized, with the payload defined as the leader (here denoted as load-leading control): the payload uses knowledge of its current state and its desired trajectory to determine the net force and moment acting upon its center of gravity required to follow the desired trajectory. Using knowledge of the cable attachment geometry, the required cable forces are computed and transmitted to the rotorcraft. The cable force optimization problem is defined and shown to be nonconvex; constraints that make the problem convex are introduced. Cable forces computed using both the convex and nonconvex formulations are compared. Controllers for both payload and rotorcraft trajectory tracking are designed. Hardware implementation that uses small single-board computers carried onboard the payload and rotorcraft is described. Flight demonstrations conducted in an indoor motion capture studio using preplanned trajectories as well as human-in-the-loop control of the payload are described to show trajectory following and rejection of impulse disturbances. An outdoor flight test showing coordinated transport in the presence of light winds is described. All calculations are hosted on the computers carried on the payload and rotorcraft, and the system is shown to be capable of real-time control and path following both for fixed and in-flight changing formations.

Modeling the capacitated p-cable trench problem with facility costs

In this work, two network design concepts which have been proven to be relevant with respect to telecommunication applications, are joined within a unified approach. First, the cable trench problem searches for cost-minimizing network structures that take into account two types of edge costs appearing in the installation of wire-based networks, namely trenching costs and cable costs. Second, the facility location problem considers the placement of shared telecommunication equipment, like switches or concentrators, together with an assignment of entities to demand nodes. Following practical needs, we join these concepts within the new capacitated cable trench problem with facility costs and service capacity in terms of number of customers that can be served by facilities. Within this setting, facility location decisions in wire-based networks can be taken under a more realistic cost scenario. A mixed-integer linear program and valid inequalities are proposed. Experiments indicate a positive impact of the valid inequalities on computational time and integrality gap.

Multi objective ant colony algorithm for electrical wire routing

Ant colony optimisation algorithms have been applied to solve wide range of difficult combinatorial optimisation problems like routing problems, assigning problems, scheduling problems and revealed remarkable solutions. In this paper we present a novel approach of ant colony optimisation algorithm to solve the electrical cable routing problem. The study focuses on optimising wire lengths, number of bends and angles of bends. We have studied these objectives in cable routing and modified the ant colony system algorithm to get better solutions. Ants are directed to search for the optimal path between the starting and the ending points by avoiding the obstacles. While ants are navigating, they travel the paths with less number of bends and consider angles of the bends towards 90, 180, and 270 degrees. Normal walls are presented as a grid and doors, windows and other obstacles are represented as rectangles. The possible points to follow by ants are designed according to the BS 7671 (IET Wiring Regulations) standards. The results of the simulation prove with comparisons that this method is feasible and effective for optimising the electrical wire routing.

Numerical Calculation of Two-Dimensional Subsea Cable Tension Problem Using Minimization Approach

Subsea cable laying is a risky and challenging operation faced by engineers, due to many uncertainties arise during the operation. In order to ensure that subsea cables are laid out diligently, the analysis of subsea cable tension during the laying operation is crucial. This study focuses on the fatigue failure of cables that will cause large hang-off loads based on catenary configuration after laying operation. The presented problem was addressed using mathematical modelling with consideration for a number of defining parameters, which include external forces such as current velocity and design parameters such as cable diameter. There were two types of subsea cable tension analyses studied: tensional analysis of catenary configurations and tensional analysis of lazy wave configurations. The latter involved a buoyancy module that was incorporated in the current catenary configuration that reduced subsea cable tension and enhanced subsea cable lifespan. Both analyses were solved using minimization through the gradient-based approach concerning on the tensional analysis of the subsea cable in differentconfigurations. Lazy wave configurations were shown to successfully reduce cable tension,especially at the hang-off section.

An evaluation of the generalized–[formula omitted] time integration scheme for a transient response of nonlinear structures

The recently developed promising generalized–α time integration scheme for nonlinear structures is evaluated and compared with Bathe scheme. The nonlinear benchmarks are developed and implemented in order to assess reliability and numerical efficiency of the schemes. Both schemes proved to be comparably efficient and accurate while Bathe method has higher frequency resolution. A practical application of the considered schemes to the nonlinear cable structure problem that support conclusions is supplied.

Electrical Layout Optimization of Onshore Wind Farms Based on a Two-Stage Approach

Electrical layouts have a significant impact on the investment cost and electrical losses of wind farms, and therefore, layouts should be optimized for reducing their share in the project budgets. In this study, a two-stage method for electrical layout optimization is given. In the first stage, the total trenching length between wind turbines and substation is minimized and in the second stage, the cabling process is performed. The contribution of this article with respect to earlier studies is twofold: First, a new theory for cabling is given and it has shown that determination of the best type of electrical cable is a priori. The suggested cabling theory reduces the complexity of the electrical layout problem since the cable related variables and constraints are avoided. Second, a new bi-objective problem is defined which allows parallel cabling over the previously defined paths. The cabling problem defined aims to minimize the net present cost of the electrical losses and initial investment costs over a known path. Moreover, a novel 3D methodology is introduced for calculating the total length of cables and trenching over the surface of the ground more accurately. All theoretical work is applied on a real onshore wind farm.

Creep deformation calculation method on sandstone rock foundation settlement of nuclear island

Most nuclear island built its foundation on the bed rock. Generally the bearing capacity of these bed rocks is very high and the settlements of these buildings are very small. But in some cases we should consider the nonlinear part of the bed rock deformation when the bedrock is sandstone, Siltstone and Shale ect. under the foundation. Because these Metamorphic deformations are mostly creep deformation. This article analyzed settlements of a nuclear island’s foundation which are much greater than it were being designed. The deformation of sandstone is very large when with high load on top of it. Long time of deformation can bring many problems in nuclear power plant, such as pipe tolerance, building connection problem, cable connection problem and can make damage of them. Compared observed dates and a calculation result by using FEM software. And here gives a simple calculation method on nuclear island foundation settlement on sandstone.

An instantaneous frequency analysis method of stay cables

This paper presents and evaluates in detail a conjugate-pair decomposition method for tracking the instantaneous frequency of a vibration signal by processing only three (or more) most recent data points, and Probability Box theory was employed to obtain the uncertain probability distribution of instantaneous frequency. A composite cable-stayed bridge with large span, named as Guanhe Bridge, was selected as the engineering background; the proposed conjugate-pair decomposition method is verified and compared with Hilbert–Huang transform method using the measured dynamical data of structural health monitoring system. Moreover, the uncertain probability distribution of instantaneous frequency was discussed; the Probability Box also can be obtained. Results show that the identify results are close to each other using conjugate-pair decomposition and Hilbert–Huang transform, respectively; but the variance of conjugate-pair decomposition is less than Hilbert–Huang transform, and conjugate-pair decomposition requires only a few data points for sliding-window fitting to extract the instantaneous frequency, and the Probability Box of instantaneous frequency will be useful to evaluate safety and potential fatigue problems in the bridge cables.

A fuzzy evidential reasoning based approach for submarine power cable routing selection for offshore wind farms

Offshore wind farms have developed fast as an environmentally friendly source of energy. The submarine power cable of the offshore wind farm, used for connecting power generation devices to onshore equipment, may have a significant impact on navigation safety and is prone to being damaged (e.g. caused by fishing or emergency anchoring by ships) when adopting unfavorable routing. This paper proposes a fuzzy evidential reasoning method for submarine power cable routing selection of the offshore wind farm by comprehensively considering the conditions for cable laying and its influence on maritime safety. The kernel of this approach is to establish a three-layer decision-making framework after fuzzification of the input variables, to derive the belief rule base, and to obtain the optimal routing from the submarine power cable candidates using evidential reasoning and index value. The proposed approach is applied to a real routing selection problem of a submarine power cable for an offshore wind farm in Zhejiang Province of China. The resulting choice corresponds to the discussions in a workshop unanimously.

Fractional cable problem in the frame of meshless singular boundary method

In this study, singular boundary method (SBM) is employed for solving fractional cable problem in two dimensional space with initial and Dirichlet-type boundary conditions. The process is modeled as a two dimensional time-fractional equation in sense of Riemann–Liouville fractional derivatives. A splitting scheme is applied to split the solution of the inhomogeneous governing equation into homogeneous solution and particular solution. We present the numerical operation for calculating the particular solution and homogeneous solution. For achieving approximation particular solution and homogeneous solution, we employ Method of Particular solution (MPS) and SBM, respectively. We use θ-weighted and finite difference method as time discretization for time derivatives. A comparison between the present method and other methods is given to show the accuracy of SBM applying on this equation. Consequently, some numerical examples with different domains are tested and compared with the exact analytical solutions to display the validity and accuracy of the numerical method in comparison with other methods.

Tree-Based Intermittent Connection Fault Diagnosis for Controller Area Network

Controller area network (CAN) is the most widely adopted network protocol in vehicle communication systems. The intermittent connection (IC) fault, a random cable connectivity problem with short durations, occurring in the CAN network may result in system performance degradation and system level failures in severe cases. Therefore, the health management of CAN-based networked systems demands effective detection and accurate localization of the IC fault. However, the diagnosis of IC fault in CAN network has not been fully exploited. This paper proposes a novel tree-based IC fault diagnosis method to identify the various IC fault locations in the CAN network. First, the error event pairs for network nodes are defined by analyzing the data-link layer information upon each error. Then, the domains of error event pairs and the information cost of IC faults included in the domains are derived. Finally, a tree-based minimal cost diagnosis algorithm is proposed to find the locations of the IC faults. Laboratory testbed is constructed and the case studies are conducted to demonstrate the performance of the proposed method. The results show that IC fault identified by the proposed method agree well with the case study setups.

TIO: A VLC-enabled hybrid data center network architecture

To satisfy the ever-increasing bandwidth demand of modern data centers, researchers have proposed hybrid Data Center Networks (DCNs), which employ high-bandwidth Optical Circuit Switches (OCSs) to compensate for Electrical Packet Switches (EPS). Existing designs, such as Helios and c-Through, mainly focus on reconfiguring optical devices to meet the estimated traffic requirements. However, these designs face two major challenges in their OCS-based networks, namely, the complex control mechanism and cabling problems. To solve these challenges, we propose TIO, a hybrid DCN that employs Visible Light Communication (VLC) instead of wired OCS design to connect racks. TIO integrates the wireless VLC-based Jellyfish and wired EPS-based Fat Tree seamlessly and combines the opposite and complementary characteristics, including wireless VLC direct connection and wired electrical packet switching, random graph, and Clos topology properties. To further exploit the merits of TIO, we design a hybrid routing scheme and congestion-aware flow scheduling method. Comprehensive evaluations indicate that TIO outperforms the Jellyfish and Fat Tree in both topology properties and network performance, and the flow scheduling method also evidently improves performance.

Performance evaluation of PMSG-based LFAC system for offshore wind power

Nowadays, the practice of Low Frequency AC (LFAC) transmission and grid integration for the multi mega-watt (MW) long distances is an interesting approach. The LFAC approach has the ability to solve the charging current problem in underground AC cables and is an alternative to the conventional offshore transmission schemes. This paper presents the Permanent Magnet Synchronous Generator (PMSG)-based LFAC transmission for offshore wind power to integrate the onshore grid. The PMSG-based offshore wind power is integrated onshore grid via LFAC and High Voltage AC for comparison. The Machine Side Converter extracts the maximum power from the wind and maintains the generator terminal voltage, whereas Grid Side Converter (GSC) maintains the constant DC link voltage by adjusting the dq currents of the grid. The simulation results demonstrate and verify the significant improvement in the power transfer capability, reduced power loss and control schemes performance. The complete work is modelled and analysed using PSCAD/EMTDC.

On the Cable Pseudo-Drag Problem of Cable-Driven Parallel Camera Robots at High Speeds

SummaryThis paper presents a control strategy for solving the cable pseudo-drag problem of cable-driven parallel camera robots at high speeds. The control strategy belongs to a hybrid position/tension control method based on cable tension optimization. The cable catenary model and cable pseudo-drag problem are considered firstly. Then, the dynamic model of the cable-driven parallel camera robot is established. The cable tension optimization is proposed. And then a control strategy is put forward and its stability is proved. Simulation results of a four-cable camera robot are presented and discussed.

Simultaneous Optimisation of Cable Connection Schemes and Capacity for Offshore Wind Farms via a Modified Bat Algorithm

Offshore wind energy has attracted worldwide attention and investments in the last decade due to the stability and abundance of wind resources. As one of the main components of this, internal array cables have a great impact on the levelised cost of energy of offshore wind farms, and thus their connection layout is a matter of concern. In this paper, a classical mathematical problem—the traveling salesman problem, which belongs to the field of graph theory—is applied to solve the offshore wind farm cable connection layout optimization problem. Both the capital investment on cables, cable laying, and the cost of power losses associated with array cables are considered in the proposed model. A modified bat algorithm is presented to resolve the problem. Furthermore, a cable crossing detection method is also adopted to avoid obtaining crossed cable connection layouts. The effectiveness was verified through a case study.

A Microcontroller-Based Remote Embedded SCADA Control System With the Aid of a 32-Bit Microcontroller

Supervisory control and data acquisition are well established control and visualization systems in industry. SCADA systems are DCS, PLC, soft PLC, industrial computer or microcontroller based. Some of those types of control are suitable for certain industries and are not for others. DCS is suitable in process control such as chemical, petrochemical, pharmaceutical industry and alike. PLCs are more suitable for food industry, beverages, car industry etc. Microcontrollers are emerging as a competitive option in small open SCADA system. All those types of control are based on data sharing using different types of networks such as Fieldbus, Profibus, Modbus and high speed ethernet. Those nets are interconnected using hard cabling which renders the communication distance very limited. One option is the use of public services such as internet but the risk is too high due to hacking, sabotage just to name few. This is demonstrated by the various conferences held over the world discussing protective ways against such practices. To overcome those problems including the cabling problem, one can call upon wireless communication with the aid of microcontroller and a SMART PHONE. This paper presents the design of a remote embedded SCADA system based on a 32 bit Microchip microcontroller. The controller has three main tasks to carry out. It controls a heat exchanger rig. It drives a multimedia graphic expansion board and it communicates with the SMARTPHONE using GSM where it interacts with the process either in normal mode or emergency mode. The proposed scheme has several advantages. It can communicate to any user independent of distance and time. It could be easily customized to allocate small and probably middle industry. On top of the cost effectiveness, the system could be expanded in local network to accommodate more complex applications.

Optimal configuration problem identification of electrical power cable in tidal turbine farm\xa0via traveling salesman problem modeling approach

Electrical power cables in tidal turbine farms contribute a significant share to capital expenditure (CAPEX). As a result, the routing of electrical power cables connecting turbines to cable collector hubs must be designed so as to obtain the least cost configuration. This is referred to as a tidal cable routing problem. This problem possesses several variants depending on the number of cable collector hubs. In this paper, these variants are modeled by employing the approach of the single depot multiple traveling salesman problem (mTSP) and the multiple depot mTSP of operational research for the single and multiple cable collector variants, respectively. The developed optimization models are computationally implemented using MATLAB. In the triple cable collector cable hub variant, an optimal solution is obtained, while good-quality suboptimal solutions are obtained in the double and single cable collector hub variants. In practice, multiple cable collector hubs are expected to be employed as the multiple hub configurations tend to be more economic than the single hub configurations. This has been confirmed by this paper for an optimal tidal turbine layout obtained with OpenTidalFarm. Suggestions are presented for future research studies comprising a number of heuristics.

Harmonious Cable Actuation Mechanism for Soft Robot Joints Using a Pair of Noncircular Pulleys

Various slim robots, such as surgical robots or humanoid robot fingers, are remotely actuated using transmission cables. If pull–pull drive is applied to actuate them using circular driving spools regardless of the shape of the joints, the tension of the driving cable becomes difficult to be maintained properly. Fortunately, it is possible to solve such a cable slack problem by providing an appropriate cable actuation length to the joint structure of the robot from the cable driving unit. Therefore, we propose a harmonious nonlinear cable actuation mechanism suitable for driving noncircular shaped joints. The proposed cable driver can mechanically provide the required cable actuation length to suit the angle change of the target joint using a pair of noncircular pulleys without increasing the number of actuators. In this paper, a design methodology of a noncircular pulley that can be applied to pulleyless rolling joints (PR joints) as well as pulleyless hinge joints is shown. Moreover, a practical cable driver is designed for actuating a hyper-redundant discrete bending joint composed of PR joints, and its effectiveness is verified through experiments. This novel cable actuation mechanism using noncircular pulleys or gears is expected to be applicable to various miniature robots such as surgical robots and animal robots of continuum structure in the future.

Free Space Intra-Datacenter Interconnects Based on 2D Optical Beam Steering Enabled by Photonic Integrated Circuits

Data centers are continuously growing in scale and can contain more than one million servers spreading across thousands of racks; requiring a large-scale switching network to provide broadband and reconfigurable interconnections of low latency. Traditional data center network architectures, through the use of electrical packet switches in a multi-tier topology, has fundamental weaknesses such as oversubscription and cabling complexity. Wireless intra-data center interconnection solutions have been proposed to deal with the cabling problem and can simultaneously address the over-provisioning problem by offering efficient topology re-configurability. In this work we introduce a novel free space optical interconnect solution for intra-data center networks that utilizes 2D optical beam steering for the transmitter, and high bandwidth wide-area photodiode arrays for the receiver. This new breed of free space optical interconnects can be developed on a photonic integrated circuit; offering ns switching at sub-μW consumption. The proposed interconnects together with a networking architecture that is suitable for utilizing those devices could support next generation intra-data center networks, fulfilling the requirements of seamless operation, high connectivity, and agility in terms of the reconfiguration time.