Parallel Cables Research Articles

A Suspended Cable-Driven Parallel Robot With Articulated Reconfigurable Moving Platform for Schönflies Motions

Cable-driven parallel robots (CDPRs) can provide large translational workspace with high payload, but their rotational capability is generally limited due to the inherent design. Additionally, among the existing topology structures of CDPRs, few lower mobility CDPRs with subspatial motions are reported till now. Aiming to narrow the abovementioned research gaps, this article presents a novel suspended CDPR with an articulated reconfigurable moving platform to generate Schönflies motions and enhance the rotational capability. The proposed robot uses four pairs of parallel cables to constrain the redundant motions. The moving platform consists of one end-effector gripper and two subplatforms, which are articulated through revolute joints. A gearbox is embedded in the moving platform to amplify the rotational motion about the vertical axis. For the proposed robot, the kinematic and static modeling is given in detail. The multiobjective optimal design is conducted to determine the dimensional parameters. The reconfiguration of the moving platform is formulated as an optimization problem and demonstrated through a case study. The interference-free static workspace is determined through a numerical approach. A prototype of the proposed robot is fabricated, and experimental tests are performed to evaluate the feasibility of the proposed robot.

Lightning inductive coupling characteristics of parallel cables: Computation and measurement validation

AbstractA simulation model composed of an interfering cable and a disturbed cable is established for studying the lightning inductive characteristics between parallel cables. Effects of the horizontal distance between cables (5–40 cm), their height difference (−6–32 cm), as well as the length of disturbed cable (1–100 m) are investigated for the cable induced voltage, which is measured at the resistive load connected between one terminal of the disturbed cable and the ground, when various lightning surge currents (8/20 μs, 5/320 μs, and 0.5 μs/100 kHz) are delivered into the interfering cable. Our findings show that an increase of horizontal distance between cables can give rise to an exponential decrease of the cable induced voltage, and that there exist linear correlations between either the height difference of two cables or the length of disturbed cable and the cable induced voltage, which reaches maximum when the cables are located at the same height and of equal length. Verification experiments for the effect of horizontal distance have also been made, and, in general, they all show a reasonable agreement with the simulations. A detailed theoretical explanation of obtained findings is provided as well.

AC-MFL testing of orthogonal cracks detection of square billet based on the flexible-printed parallel cable magnetizer

Longitudinal and transverse cracks that appear in the manufacturing and processing of square steel billets are a critical safety hazard. An integrated alternating current magnetic flux leakage (ACMFL) detection probe is composed of parallel cables (PC) magnetizer and pick-up coils manufactured by flexible printed circuit (FPC). Experiments verified the probe could detect longitudinal and transverse cracks in a unidirectional scan. It was proven that when the probe scans the cracks parallel to the direction of the magnetic flux line, the signal at the end of the crack mainly originates from the local magnetic flux leakage (LMFL) field. With an increase in the frequency, the LMFL characteristics become more obvious. Experiments show that the probe can effectively detect longitudinal cracks with a width of 0.4 mm or more when the depth is 0.4 mm, and cracks with a depth of more than 0.3 mm when the width is 1.0 mm in the axial scanning.

Theoretical analysis and design of fire protection and thermal insulation of parallel wire or strand cables

In this study, a transient heat flow model has been established for parallel wire or strand cables at high temperature by employing the lumped thermal mass approach, and the numerical solution of the surface temperature as a function of time in each layer of the steel wire or strand inside the cable was calculated. Accuracy of the theoretical method is verified through uniform heating test of 73Φ15.7 mm steel strand cable. The results calculated show that temperature field inhomogeneity of cable section is overestimation on the condition that heat conduction inside the cable is not considered. Considering heat conduction or not, the maximum temperature difference of the core steel stand at the same time point is 373 . Unprotected 73Φ15.7 mm cable is damaged in only 12 min in UL1709 fire, and arrangement of fire protection layer around cable can effectively retard the temperature rise of cable surface. The experimental results are in good agreement with the theoretical calculation values in early stage of fire, and the temperature difference between the two is within 10%. Besides, the numerical calculations were analyzed in accordance with the fire protection requirements limiting the surface temperature of cables. It was observed that the minimum thickness of the fire protection layer required to meet the PTI DC45.1-12 standard was linearly related to the numerical value of the section factor of the outermost layer of steel wires or steel strands in the equivalent model, and the slope of the function was approximately equal to the conduction coefficient of fire protection layer, as the cable was subjected to fire for 30 min. Further, based on this, a simple method was proposed to calculate the minimum thickness of the fire protection layer for parallel wire or strand cables.

TENSE CONDITION OF DEEP INSERT ROPES

The problem of determining the stress state of deep anchor rope anchors between structural elements is solved in the scientific work. The purpose of this work was to develop a method for determining the stress state of deep anchor rope anchors in order to increase the level of safety of mining operations and maximize the monolithic nature of the rock formation. According to the goal, the main task was to study the relationship between the elements of rope anchors and the nature of the load distribution.
 An analysis of recent work and publications has shown that the use of a single anchor is uneven distribution of load fields, high concentration of stress forces around the perimeter of the structure and the formation of uneven zones of inelastic deformations. However, the stress forces are reduced by using several rope anchors, leaving local perturbations. Attempts to reduce local perturbations on the surface of the tectonic layer of the rock led only to an increase in current.
 The model of interaction of an anchor through a layer of a fixer with an array of rock mass is formed. In the anchor, the cable is much smaller in diameter than the size of the array in the plane it is normal. As a result, the compressive stiffness of the array in the direction of the parallel cable can be assumed to be infinite. The cross section of the anchor cable will be considered round. The cable is located in a cylindrical bore. Assume that their axes coincide. There is a fastener between the array and the cable. Its outer surface is stationary and transmits only tangential stresses. The inner surface of the fastener interacts with the outer surface of the cable without the possibility of their mutual displacement.
 According to this model, our proposed method of determining the stress state allows you to calculate the stress forces and set the allowable characteristics at the stage of manufacture of rope anchors. It is also possible to determine the stress state of the elements of the deep anchor rope anchors, in particular the tangential stresses on the surface of the adhesive bond of the cable and fastener. According to the results, the prospects of the study are analytical calculations of this design and derivation of optimal parameters of rope anchors.

Dynamic response and damage mechanism of parallel wire cables under contact explosion

With the global threat of terrorism on the rise, the protection of important infrastructure such as cable-stayed bridges from terrorist assaults has become a major concern. In cable-stayed bridge designs, the cables are crucial load-carrying components, and their failure could result in the progressive collapse of the bridge with catastrophic results. However, there is very limited understanding of the blast effects on cables. This paper presents a study on the blast performance of parallel wire cables under contact explosions. Field blast tests were conducted on four identical parallel wire cable specimens with varying charge weights and prestress levels. Arbitrary-Lagrangian-Eulerian (ALE) algorithm is utilized to develop the numerical model in LS-DYNA. The numerical model is then validated and further used to investigate the damage mechanism of the cable under contact explosions. The results indicate that the damage process of cables under contact blasts can be divided into three stages: Compression, divergence, and stretching. The wires arranged in angular points facing the detonation are particularly vulnerable, and high-density polyethylene (HDPE) is prone to be pelted off by explosive pressure. Parametric analyses were carried out to investigate the influences of charge weight and prestressing force on the damage degree of cables. The relationship between the TNT equivalent and the number of fracture wires is derived from the parametric analysis results. Furthermore, the prestress is found to have a considerable impact on the degree of cable damage induced by contact explosions. Taking prestress into account, a damage evaluation method for blast-damaged cables is proposed.

A Novel AC-MFL Probe Based on the Parallel Cables Magnetizing Technique

A Novel AC-MFL Probe Based on the Parallel Cables Magnetizing Technique

Design of a Planar Cable-Driven Parallel Crane Without Parasitic Tilt

Abstract Cable-driven parallel robots (CDPRs) offer high payload capacities, large translational workspace, and high dynamics performances. Their rotational workspace is generally far more limited, however, which can be resolved using cable loops, as was shown in previous research. In the case of fully constrained CDPRs, cable loops can induce unwanted torques on the moving-platform (MP), causing it to tilt and move away from its intended position, which we call parasitic tilt. Hence, the orientation accuracy of such robots is usually limited. This paper deals with the design, modeling, and prototyping of a planar CDPR with infinite rotations, without parasitic tilt and without an additional motor. This robot, which we call a cable-driven parallel crane (CDPC), is composed of a mobile platform (MP) with an embedded mechanism and a transmission module. The MP is linked to the frame by four cables, three of them acting in parallel, forming in effect a double parallelogram. Among these three parallel cables, two form a cable loop, i.e., they are two strands of the same cable redirected to and from the MP through an embedded pulley. The two-degree-of-freedom (dof) motions of the moving-platform of the CDPC and the internal dof of its embedded mechanism are driven by a total of three actuators, which are fixed to the frame. As a consequence, the overall system is fully actuated, its total mass and inertia in motion is reduced, and it is free of parasitic tilts.

Theoretical and experimental examination of simple coaxial photonic crystals for undergraduate teaching

A study implementing a coaxial photonic crystal with a simple structure composed of only one type of coaxial cable is described. The coaxial photonic crystal consists of alternating sections of a single cable and N parallel cables, with impedances of ZH and ZH/N, respectively. The high mismatch in impedance at the interfaces enables access to a highly superluminal group velocity with few cables. An easily realizable method is also presented to measure both the amplitude of transmission and the phase of the crystal by using an oscilloscope and a function generator. The measurements were validated by an advanced vector network analyzer and matched the results of theoretical analysis based on the transfer matrix method. The experiment only requires electronic components and equipment that are typically used in undergraduate teaching laboratories.

Study on optimization of laying mode of two parallel high voltage cables in the same phase of two circuits

In power lines, the proportion of parallel cables is gradually increasing, but the uneven current distribution and sheath circulation affect the safe and stable operation of parallel cables. Existing studies show that cable current and sheath circulation are obviously affected by cable laying mode. At present, the designed cable laying mode is as “pin” laying and horizontal “I” laying. Combined with the above engineering difficulties, this paper focuses on the parameter optimization scheme of 220 kV two circuit parallel cables in the same direction when the metal sheath is cross connected and grounded. Firstly, the operation model of 220kV two circuits in-phase two parallel cables is established. The numerical differences between the current distribution non-uniformity coefficient and sheath circulating current of the cables are analyzed and calculated under the condition of “pin” laying and horizontal “I” laying. Meanwhile, the influence of different phase sequence arrangement on the current distribution non-uniformity coefficient and sheath circulating current of the cables is compared. Secondly, the cable laying mode of “symmetrical pin” is designed, and the improvement effect of uneven coefficient of cable current distribution and metal sheath circulating current under “symmetrical pin” laying is compared and analyzed. Finally, the differences of the above parameters in different phase sequence arrangements are compared and analyzed. The research results show that the symmetrical pin laying can improve the uneven distribution of current and sheath circulating current, which has important engineering practical value.

Flexible Printed Probe for Orthogonal Cracks Detection of Square Billet Based on the Parallel Cables Magnetizer

Flexible Printed Probe for Orthogonal Cracks Detection of Square Billet Based on the Parallel Cables Magnetizer

An F-Actin Mega-Cable Is Associated With the Migration of the Sperm Nucleus During the Fertilization of the Polarity-Inverted Central Cell of Agave inaequidens.

Asparagaceae’s large embryo sacs display a central cell nucleus polarized toward the chalaza, which means the sperm nucleus that fuses with it during double fertilization migrates an atypical long distance before karyogamy. Because of the size and inverted polarity of the central cell in Asparagaceae, we hypothesize that the second fertilization process is supported by an F-actin machinery different from the short-range F-actin structures observed in Arabidopsis and other plant models. Here, we analyzed the F-actin dynamics of Agave inaequidens, a classical Asparagaceae, before, during, and after the central cell fertilization. Several parallel F-actin cables, spanning from the central cell nucleus to the micropylar pole, and enclosing the vacuole, were observed. As fertilization progressed, a thick F-actin mega-cable traversing the vacuole appeared, connecting the central cell nucleus with the micropylar pole near the egg cell. This mega-cable wrapped the sperm nucleus in transit to fuse with the central cell nucleus. Once karyogamy finished, and the endosperm started to develop, the mega-cable disassembled, but new F-actin structures formed. These observations suggest that Asparagaceae, and probably other plant species with similar embryo sacs, evolved an F-actin machinery specifically adapted to support the migration of the fertilizing sperm nucleus within a large-sized and polarity-inverted central cell.

Research on the Orientation Error of the Translational Cable-Driven Parallel Robots

Abstract Parallel cables are widely used in cable-driven parallel robots (CDPR) to provide constraints to the end-effector and to realize translational degrees-of-freedom(DOFs). However, when there are structural errors, parallel cables become no longer parallel and will cause orientation errors of the end-effector, which cannot be compensated by kinematic calibration. In this paper, the orientation assurance method is studied considering a 3DOFs translational CDPR. First, the kinematic model and error mapping model of the CDPR are established by using the closed-loop method, considering the pulley radius. Second, the influence of the structural parameters errors on the error of the end-effector is analyzed with the sensitivity index, which establishes a theoretical basis for the simplification of the accuracy synthesis process. Third, the design tolerances of the cable connection points are determined through accuracy synthesis, which is implemented with the genetic algorithm considering the optimal manufacturing cost and the orientation constraints of the end-effector. Finally, to reduce the influence of cable length error, the method of adjusting the initial pose was proposed and studied, which is verified as an effective approach to reduce the orientation error.

Resilient electrical distribution grid planning against seismic waves using distributed energy resources and sectionalizers: An Indian's urban grid case study

The urban and suburban advancement has increased the consumption of energy per capita gradually. Electrical distribution companies have expanded their network to cater to the demand, making the system more vulnerable to low probability high impact events. The extreme events occurred in last five year had shown us complete to partial blackout, which calls for resiliency enhancement. The presented study concentrates on the Dehradun, India, which listed as the most earthquake-prone region by Union Nations Development Programme. Hence, this paper proposes three main strategies to make a resilient distribution grid against an earthquake; (i) Hardening approach at grid side and demand side against earthquake disaster (ii) Monte-Carlo methodology for earthquake hazard model (iii) K-means algorithm with clustering quality index to identify the multiple vulnerable zones. Grid side hardening is performed using the optimal unit placement of the Solar PV plant (SPP) with storage and parallel cables with sectionalizers. For demand-side hardening, electric vehicles are considered storage after an event, duly taking their future growth rate into account. Furthermore, a Mixed Integer non-linear problem is formulated to identify the optimal sizing and sitting of SPP with storage. The proposed methodology is developed and applied to the distribution system (156-bus) of Dehradun, India.

A Novel Shape Finding Method for the Main Cable of Suspension Bridge Using Nonlinear Finite Element Approach

The determination of the final cable shape under the self-weight of the suspension bridge enables its safe construction and operation. Most existing studies solve the cable shape segment-by-segment in the Lagrangian coordinate system. This paper develops a novel shape finding method for the main cable of suspension bridge using nonlinear finite element approach with Eulerian description. The governing differential equations for a three-dimensional spatial main cable is developed before a one-dimensional linear shape function is introduced to solve the cable shape utilizing the Newton iteration method. The proposed method can be readily reduced to solve the two-dimensional parallel cable shape. Two iteration layers are required for the proposed method. The shape finding process has no need for the information of the cable material or cross section using the present technique. The commonly used segmental catenary method is compared with the present method using three cases study, i.e., a 1666-m-main-span earth-anchored suspension bridge with 2D parallel and 3D spatial main cables as well as a 300-m-main-span self-anchored suspension bridge with 3D spatial main cables. Numerical studies and iteration results show that the proposed shape finding technique is sufficiently accurate and operationally convenient to achieve the target configuration of the main cable.

Muon Tracker with Unsegmented Plastic Scintillator Panels

A muon tracker was developed using three polyvinyl toluene scintillator panels instrumented with photomultiplier tubes (PMTs) mounted at the corners. Panels are mounted in parallel on an aluminum frame which allows for simple adjustment of angle, orientation and separation distance between the panels. The responses of all PMTs in the system are digitized simultaneously at sub-nanosecond sample spacing. Software was developed to adjust settings and implement event rejection based on the number of panels that detected a scintillation event within a 400-nanosecond record. The relative responses of the PMTs are used to calculate the position of scintillation events within each panel. The direction of the muons through the system can be tracked using the panel strike order. Methods for triangulation by both time-of-flight (TOF) and PMT magnitude response are reported. The time triangulation method is derived and experimentally demonstrated using parallel cables of differing length. The PMTs used in this experiment are only optimized for amplitude discrimination, not for time spread jitter as would be required to implement TOF methods into the scintillator panels. A Gaussian process regression machine learning tool was implemented to learn the relationship between PMT response features and positions from a calibration dataset. Resolution is analyzed using different numbers of PMTs and low-versus-high PMT sensitivities. Muons traveling in forward and reverse directions through the detector system were counted in all six axis orientations. The muon detector was deployed for 28 days in an underground tunnel and vertical muon counts were recorded.

ВИЗНАЧЕННЯ ОПТИМАЛЬНОЇ КРИВИЗНИ ПРУЖНО ДЕФОРМОВАНИХ ВАНТ ПОСЕРЕДИНІ ПРОЛЬОТУ У ВИСЯЧОМУ ПОКРИТТІ ЗА ДОПОМОГОЮ КОМП’ЮТЕРНОЇ СИСТЕМИ MATHCAD

Abstract. The paper presents the theoretical results of improving and refining the general methodology for selecting the cross section of a flexible elastic thread for cable-stayed using the capabilities of computer programs. A technique is proposed for finding the optimal curvature of the cable in the middle of the span by compiling the target function of the cable cost and coverage and determining its minimum. The hanging coating of the building is considered, consisting of parallel-located flexible cables. Coating elements are laid on them. It is assumed that the load is evenly distributed over the curved surface of the coating. With this application of load, the sag curve is adopted as a chain line. In the calculation, two states of the thread are considered. In the first state, it is loaded with a linear load uniformly distributed along its length from its own weight. In the second state, the thread is loaded with the total calculated linear load evenly distributed along its length. To select the cross section of the thread, the maximum longitudinal force arising in it in the second state is determined, which depends on the curvature in the middle of the span. This curvature is determined on the basis that the difference between the lengths of the thread in the first and second states is equal to the elastic elongation according to Hooke's law. Using ordinary algebraic methods, solving the problem is quite complicated. Therefore, it was proposed to solve it using the MathCAD computer system. With the found value of the curvature in the middle of the span, the required cross-sectional area of the thread is calculated. After that, the appropriate rope is selected according to the assortment. To optimize the cable-stayed coating, the optimal curvature in the middle of the span is determined in the first state, at which the total cost of cable-stayed and coating will be minimal. For this purpose, the objective function of the cost of the cable and the coverage that lies on this cable has been compiled. To determine the optimal curvature, it is proposed to accept a series of values of this curvature with some step in a certain range. For each curvature, the value of the objective function is calculated. Using the MathCAD computer system, it is proposed to build the graph of the objective function and find the value of the optimal curvature at which this function has a minimum. After that, it is proposed to find the corresponding optimal sagging arrow. The proposed method allows us to determine the optimal parameters of the hanging coating with parallel cables on the basis of the minimum cost, as well as to calculate the necessary cross-sectional parameters of the flexible cable from the strength condition.

Development of Cable-driven Anthropomorphic Robot Hand

This letter presents a novel design of an anthropomorphic robotic hand. By using a parallel plate knuckle with a universal joint, it is possible to achieve two degree of freedom (DOF) at a joint of a finger with wide working range in the proposed design. Each degree of freedom of the robotic hand is driven by parallel cables with single motor that mimics the muscle antagonism of the human hand. The proposed robotic hand embodies human-like features and achieves an adaptive grasping capability by adopting compliant coupling between the distal and the proximal interphalangeal joints. Experiments are conducted to validate the performance of the robotic hand.

Multi-Pair Cable Measurements for 5G Indoor Service Provisioning

This paper considers the 5G new radio (NR) indoor service provisioning scenario where the CPRI link terminates at remote radio unit (RRU) in the building and multi-pair cable, i.e. CAT-5, is used to provide connectivity between distributed antenna unit (DAU) and RRU. The paper focuses on the de-tailed methodology for multi-pair copper channel measurement including measurement equipment specifications, their respective settings, measurement parameters i.e. characteristics impedance, insertion loss (IL), far-end-crosstalk (FEXT) and near-end-crosstalk (NEXT). The measurements include the cables for next-generation multi-pair system, where multi-pair cables, i.e. CAT-5 cables, are used from the RRU to the DAUs in a building. Conventionally, many multi-pair cables share the same duct in a building and interfere with each other, therefore two parallel multi-pair CAT-5 cables of 50m each are considered for the measurement scenario. This setup result in 4 twisted pairs terminate at each DAU and this configuration is termed as next-generation multi-pair MIMO (NGMM). The number of twisted pairs is increased by using the Phantom mode circuit connected to the opposite ends of each CAT-5 cable and the resulting configuration is called next-generation multi-pair super MIMO (NGMSM). The cable parameters have been measured for frequencies up to 1 GHz and 250 MHz for NGMM and NGMSM, respectively. DL data rate of each configuration is examined by applying conventional block diagonalization.

Study on Optimization of Laying Mode of Two Parallel High Voltage Cables in the Same Phase of Two Circuits

Study on Optimization of Laying Mode of Two Parallel High Voltage Cables in the Same Phase of Two Circuits