Large Traction Force Research Articles

Mechanics Model of Driving Wheel of Wheel Tractor Based on Furrow Effect and Adhesion Effect and a Novel Design Method of Driving Wheel with Large Traction Force

Mechanics Model of Driving Wheel of Wheel Tractor Based on Furrow Effect and Adhesion Effect and a Novel Design Method of Driving Wheel with Large Traction Force

Increasing the efficiency of trenchless laying machines using vibrating knives

Modern requirements for the laying of underground communications consist of a combination of high construction rates with low energy consumption. The highest rate of laying linear objects is ensured by knife-type cable and pipe-layers, which are designed for their trenchless burial - this is when a narrow slot is cut in the soil, through which a cable or pipeline is launched. A feature of this process is the need to use large traction forces, which are determined by the resistance forces of the soil when cutting it. Accordingly, the cutting resistance of the soil depends on the dimensions of the width and depth of the gap and the physical and mechanical properties of the soil. Finding ways to reduce forces for deep cutting of soils is an important problem.
 One of the ways to improve the efficiency of trenchless laying machines is to equip them with vibrating knives. It is known that when the knife oscillates in the vertical direction, it leads, depending on the soil and the speed of movement, to a 30…60% decrease in traction resistance. But the use of more complex vibration movements of the knives allows reducing the traction resistance during deep cutting of soils by 70…90%. It is well-known that various designs of mechanical drive are used to implement the process of vibration of knives. These are complex devices that, together with the entire machine, require calculations. Therefore, studying the forced vibration of the knives of pipe deepeners is an urgent task, which is aimed at reducing the energy consumption of the process of soil deep cutting and improving the overall performance of knife machines for trenchless laying of underground utilities.
 To achieve the goal, the paper considered possible variants of the vibration oscillation of the knives and provided calculation dependencies for determining the resistance of soil cutting by active knives; also the dependence for determining the maximum average drive power of a centralized unbalanced vibrator was given. At the same time, the dimensions of the gap obtained, the physical and mechanical properties of the soil and the technical characteristics of the vibrator were taken into account.The obtained recommendations can be used when designing trenchless laying machines using vibrating knives.

TRANSPORT AND TECHNOLOGICAL MODULE WITH ELECTRIC WHEEL DRIVE

Agriculture of the Russian Federation suffers huge losses due to the lack of the necessary equipment to work on soils with low load-bearing capacity. As a result, harvesting of winter crops takes more than 40 days, and crop losses amount to 42 percent. When applying fertilizers, about 40 percent of the soil surface is compacted by the wheels of agricultural machinery. Compaction of the soil leads to the appearance of large and dense blocks of earth during plowing. Tractors of traction classes 1,4-5 are used as part of the tractor fleet of peasant farms. Such a nomenclature of tractor types leads to additional costs associated with low annual loading of tractors, over-compaction of soils, tractors of high traction classes. (Research purpose) The research purpose is justifying the use of a transport and technological module with an electric wheel drive. (Materials and methods) Gave a schematic diagram of a modular power-technological means and a kinematic scheme of the wheel drive of a transport and technological module. (Results and discussion) We have developed a transport and technological module with an electric drive of the driving wheels from the generator, which in turn rotates due to the tractor power take-off shaft connected by a cardan transmission. It was determined that the electronic control unit and wheel speed sensors are responsible for the necessary kinematic correspondence between the driving wheels of the tractor and the transport and technological module. It was found that this eliminates the need for a synchronous power take-off shaft on the tractor and, as a result, makes the technological module universal. (Conclusions) It was shown that the use of a transport and technological module with an electric wheel drive serves as an effective way to solve the problem of ballasting and makes it possible to improve the technological properties of a second-generation tractor. It was stated that the use of a transport and technological module with an electric wheel drive will allow the tractor to be used to perform transport work requiring a large traction force on soils with low load-bearing capacity, such as the transportation of forests, manure in the spring and autumn thaw and others.

An investigation into printing pressure of 3D printed continuous carbon fiber reinforced composites

3D printing of continuous carbon fiber reinforced polymer (CCFRP) composites is an innovative manufacturing technology of composites. This research developed a novel 3D-printed extruder to fabricate CCFRP composites using an in-situ impregnation technique. The printed CCFRP composites present relatively low void content and competitive mechanical properties due to the well impregnation of carbon fibers. The printing pressure during the 3D printing was analyzed with an in-situ traction force monitor system. The effect of printing pressure on mechanical properties and void distribution of 3D-printed CCFRP composites was then investigated by adjusting the layer thickness. It demonstrates that a thinner printing layer can generate a larger ironing force, minimizing the void formation, thus improving the mechanical properties and surface quality of final parts. However, the large traction force would reduce the dimension accuracy. A trade-off between dimension accuracy and mechanical properties should be made when optimizing the processing parameters of 3D printing.

A Surgical Robotic System for Long-Bone Fracture Alignment: Prototyping and Cadaver Study

In this paper, we design, develop, and validate a surgical robotic system, entitled Robossis, to assist long-bone fracture reduction, i.e., alignment, surgeries. Unlike traditional long-bone fracture surgeries, Robossis enables the surgeon to precisely align the fractured bone in the presence of large traction forces and torques. The proposed surgical system includes a novel 3-armed robot, a bone-gripping mechanism, and a master controller. The 6-DOF 3-armed wide-open parallel robot has a unique architecture, which facilitates positioning the bone inside the robot, providing a large workspace for surgical maneuvers. Kinematic analysis shows that the symmetric 3-armed mechanism provides a significant advantage over the Gough-Stewart platform, i.e., 15 times larger rotational workspace, which is a vital advantage for fracture alignment. Theoretical and experimental testing are performed to demonstrate Robossis performance, including high accuracy and force insertion capabilities. A successful cadaver test was performed using a Robossis prototype, which shows that guided by intraoperative X-ray imaging, Robossis is able to manipulate bone in all translational and rotational directions while encountering the muscle payload surrounding the femur. Robossis is designed to balance accuracy, payload, and workspace, and its innovative design presents major advantages over the existing robot designs for the reduction of long-bone fractures.

Current status and research advances on the use of assisted traction technique in endoscopic full-thickness resection

Endoscopic full-thickness resection (EFTR) allows completely resecting deep submucosal tumors (SMTs) in the gastrointestinal wall, which has a broad application prospect in clinic. However, its application and promotion are limited by complex surgical procedures and high surgical risk. Various auxiliary traction techniques are expected to reduce the operation difficulty and risk of EFTR and improve its operative success rate. To provide a reference for clinicians, we summarize various auxiliary traction techniques in EFTR in this article. The clip-with-line method is simple to operate and widely used, whereas its traction is limited and there is a risk of clip falling off. The snare traction method and the clip-snare traction method has advantage of large traction force, but its thrust is affected by the hardness of snare. The traction point of the grasping forceps traction method is flexible and easy to adjust. Nevertheless, it requires the use of a dual-channel upper endoscope, which is difficult to operate. The transparent cap traction method and the full-thickness resection device traction method takes a short time and is easy to promote, whereas the resectable lesion is limited, and the size of the lesion may affect the success rate. In contrast, the suture loop needle-T-tag tissue anchors assisted method has a large resection range, but the operation is complicated and the feasibility has not been verified. The robot-assisted method has flexible operation and excellent visualization, whereas it is expensive and difficult to operate. There is no report of the application of magnetic anchor technology in EFTR, but it may have good application prospects in the auxiliary traction of EFTR.

Design and analysis of a hydraulic drive downhole traction in-pipe robot based on flexible support structure

For the strict requirement of convey tools in horizontal well operation, this paper proposes a hydraulic drive downhole traction in-pipe robot based on the flexible support structure, which has the characteristics of compact structure, large traction force, and high reliability. Based on the design of mechanical structure, the motion principle of the robot continuous propulsion is analyzed. Analysis of mechanical characteristics of the flexible support structure is obtained. Hydraulic system including some key hydraulic components are designed and analyzed. Control strategy of purely hydraulic drive mode is researched. Simulation analysis and experimental platform are all accomplished to prove feasibility of purely hydraulic drive mode, and some parameters that affect the robot performance are discussed. Results show that the novel in-pipe robot has a total length of 3.4 m and can adapt to borehole diameter of 155–218 mm. When load is 15 kN, robot motion speed reaches 0.12 m/s. What is more, this novel traction robot does not require an electric power source and has great advantages in safety and reliability, which shows considerable potential for the downhole operation.

Design and Analysis of a Low-Speed and High-Torque Dual-Stator Permanent Magnet Motor With Inner Enhanced Torque

Given the problem that the drive system of the traditional mine transportation winch outputs a large traction force through the cooperation of an induction motor and reducer to meet the needs of a large traffic volume and heavy-load starting, this paper studies a low-speed and high-torque dual-stator permanent magnet direct drive motor with a separated magnetic circuit. The inner motor is a torque motor, and the outer motor is a direct drive motor, which is characterized by no magnetic circuit coupling and independent control. The proposed motor has an excellent heavy load starting ability and operation efficiency, and it improves the output torque without increasing the motor volume, which belongs to a special application. According to the working characteristics of the inner and outer motors and the constraints between the overall dimensions, the size equation is derived, and the design principles of the electromagnetic parameters, pole-slot combination and winding structure are described. The torque characteristics and temperature rise characteristics of the motor are simulated using the finite element method and compared with the torque performance and electromagnetic materials cost of the single stator low-speed and high-torque permanent magnet motor with different rotor structures. The results show that the proposed motor has a high torque density and starting torque, and it greatly reduces the motor volume on the basis of a small cost difference.

Mechanical Model of Drilling Robot Driven by the Differential Pressure of Drilling Fluid

A new type of drilling robot driven by drilling fluid is proposed, whose traction force is provided by differential pressure inside and outside of the drilling robot. The fluid mechanical model of differential pressure is established based on the principle of pressure drop. The equations for calculating the traction force of the robot in no-load condition and load condition are derived respectively. The dynamic model of drilling robot is established and the calculation method of key parameters such as weight on bit (WOB) and rate of penetration (ROP) in the dynamic model is derived. The influence of flow rate of drilling fluid on ROP/velocity and traction force of the drilling robot is analyzed. Among them, with the increasing of flow rate, the ROP/velocity and the traction force of drilling robot increases in a nearly linear trend. In the no-load condition (traction process), the drilling robot will be in acceleration until the telescopic cylinder stops pumping drilling fluid. In the load condition (drilling process), the drilling robot will reach a balance with the mechanical drilling rate within 0.1s. The proposed drilling robot can provide the possibility for the downhole operations in horizontal well with long displacement or in the condition of large traction force request. What’s more, this paper will provide a theoretical guidance for the control of ROP and WOB in the drilling process, and promote the application of drilling robots.

A Novel Double Bevel Support Structure for Downhole Robot

Downhole robot is driven by friction force between the downhole robot and the borehole wall. The traction force $$=$$ friction coefficient * support force. The friction coefficient is generally ranging from 0.1 to 0.4, and the support force is usually small. So the traction force of the downhole robot has been subject to the objective conditions. In order to improve the traction force, in this paper, a novel downhole robot with double bevel self-locking structure (DBSS) is invented. The mechanical model of the DBSS is established. And the mathematical equations of mechanical model are deduced according to the mechanical model. Furthermore, the angle ranges of the bevels and the friction coefficient of each contact surface are obtained. Then, an experimental device of DBSS is designed and fabricated. And the experimental results show that the experimental data are basically the same as the theoretical calculation values. The proposed DBSS will have a great application prospect on downhole robot with large traction force. And the DBBS will reduce the damage produced by the friction block compared with the cam self-locking structure.

Rigid External Distraction with Intranasal Bone-borne Traction Hooks for Midfacial Hypoplasia

Rigid external distraction is currently performed to correct cases of severe maxillary hypoplasia. As an improvement of this technique, we propose the use of an intranasal bone-borne traction hook. This study is a retrospective chart review of the intranasal bone-borne traction hooks used in the treatment of severe maxillary hypoplasia. There were 110 patients treated with the hooks from 2005 to 2017. The maximum traction force was 7.75 kg, and there were few complications encountered during distraction. There were 76 patients who had the hooks removed under local anaesthesia. A cephalometric analysis was conducted in 56 patients. The average advancement of A-point was 9.9 ± 4.2 mm, 8.4 ± 2.5 mm, 11.0 ± 3.7 mm, 17.9 ± 4.4 mm for the trans-sutural distraction osteogenesis (DO), maxillary anterior segment DO, Le Fort I osteotomy DO and Le Fort III/II osteotomy DO, respectively. The average changes of sella-nasion-point A (SNA) were 8.89 ± 4.30 degrees, 8.21 ± 3.17 degrees, 10.49 ± 3.26 degrees, and 15.10 ± 4.00 degrees, respectively. The A point-nasion-B point (ANB) also showed increases in all procedures with P < 0.001. In conclusion, this technique sufficiently advances the midface and ensures the scars are concealed in the nasal base. The traction hook can bear a large traction force, causes minimal complications and is easily removed.

Modeling of rolling contact fatigue in rails at the microstructural level

A micromechanical-based finite element framework is developed to investigate the rolling contact fatigue (RCF) in rails. The microstructure of a representative part of the rail in contact with the wheel during wheel passage is modeled using Voronoi tessellation algorithm. The geometry explicitly represents microstructural grain and grain interface features that represent actual microstructure of rail steel. The grain interface is modeled using cohesive elements. For higher computational efficiency, moving Hertzian load is applied to the rail surface instead of moving the wheel explicitly on top of the rail. The jump-in-cycles approach is employed to efficiently simulate a large number of loading cycles, while the material degradation at the grain interface is represented by an accurate damage evolution law. Additionally, the model is used to evaluate the effects of temperature change, traction coefficient, and grain size on initiation and progression of RCF. The results indicate that colder temperatures increase the progression of RCF, while warmer temperatures do not have any significant effects. Large traction forces at the wheel-rail interface significantly accelerate RCF growth, mainly through migration of subsurface micro-cracks to the surface of the rail. The surface cracks grow into larger ones that lead to loss of rail material. Controlling the grain size can have a positive effect on both the initiation and migration of sub-surface cracks. Changing yield strength of material with the Hall-Petch relation, the model evaluates the effect of refining the grain size. The results indicate that smaller grains can improve RCF properties of the rail. The effect of maximum contact pressure on RCF is studied, and the results show a power relation between maximum contact pressure and RCF life. Also several case studies are simulated and compared with the experimental observations. The simulation results are in close agreement with the experimental observations for the crack pattern and crack depth.

Dia1-dependent adhesions are required by epithelial tissues to initiate invasion.

Developing tissues change shape and tumors initiate spreading through collective cell motility. Conserved mechanisms by which tissues initiate motility into their surroundings are not known. We investigated cytoskeletal regulators during collective invasion by mouse tumor organoids and epithelial Madin-Darby canine kidney (MDCK) acini undergoing branching morphogenesis in collagen. Use of the broad-spectrum formin inhibitor SMIFH2 prevented the formation of migrating cell fronts in both cell types. Focusing on the role of the formin Dia1 in branching morphogenesis, we found that its depletion in MDCK cells does not alter planar cell motility either within the acinus or in two-dimensional scattering assays. However, Dia1 was required to stabilize protrusions extending into the collagen matrix. Live imaging of actin, myosin, and collagen in control acini revealed adhesions that deformed individual collagen fibrils and generated large traction forces, whereas Dia1-depleted acini exhibited unstable adhesions with minimal collagen deformation and lower force generation. This work identifies Dia1 as an essential regulator of tissue shape changes through its role in stabilizing focal adhesions.

Path Tracking for a Skid-steer Vehicle using Model Predictive Control with On-line Sparse Gaussian Process

Skid-steer vehicle can generate a large traction force, which is especially good for navigation on a rough terrain. However, the turning motion is so sensitive to slippage effect that designing a controller is still challenging problem. Also, the motion of the vehicle is affected not only by wheel motion, but also by the road properties and the characteristics of wheel control. With this in mind, we employ a model predictive control (MPC) with an on-line model learning. The velocity model, which represents the relationship between true vehicle velocity and input command, is learned with an on-line sparse Gaussian process (GP). The on-line sparse GP can reduce the computational complexity of GP and also consistently update the model from the driving data. Finally, combining with MPC makes it possible to generate an optimal policy based on the learned model. Experiments are conducted to test the tracking performance of skid-steer robot. The results show the more reliable performance than the method based on a conventional model with parameter adaptation.

Design and analysis of cleaning mechanism for an intermittent screw-driven pipeline robot

For achieving the compact size and large traction force of cleaning robots, this paper presents an intermittent-cleaning robot based on the screw-driven mechanism. The robot has two working modes: Linear reciprocating cleaning (LRC) mode and Spiral reciprocating cleaning (SRC) mode. The working principle, kinematic analysis, traction and driving force calculations for both working modes, were obtained and compared. Furthermore, in order to ensure the working stability, the failure mode analysis was performed. Simulation and experiments were conducted to verify the proposed robotic mechanism. The results show that the proposed intermittent-cleaning robots can effectively complete the cleaning work of the pipeline.

The Role of Stress Fibers in the Shape Determination Mechanism of Fish Keratocytes

Crawling cells have characteristic shapes that are a function of their cell types. How their different shapes are determined is an interesting question. Fish epithelial keratocytes are an ideal material for investigating cell shape determination, because they maintain a nearly constant fan shape during their crawling locomotion. We compared the shape and related molecular mechanisms in keratocytes from different fish species to elucidate the key mechanisms that determine cell shape. Wide keratocytes from cichlids applied large traction forces at the rear due to large focal adhesions, and showed a spatially loose gradient associated with actin retrograde flow rate, whereas round keratocytes from black tetra applied low traction forces at the rear small focal adhesions and showed a spatially steep gradient of actin retrograde flow rate. Laser ablation of stress fibers (contractile fibers connected to rear focal adhesions) in wide keratocytes from cichlids increased the actin retrograde flow rate and led to slowed leading-edge extension near the ablated region. Thus, stress fibers might play an important role in the mechanism of maintaining cell shape by regulating the actin retrograde flow rate.

Epitaxially grown collagen fibrils reveal diversity in contact guidance behavior among cancer cells.

Invasion of cancer cells into the surrounding tissue is an important step during cancer progression and is driven by cell migration. Cell migration can be random, but often it is directed by various cues such as aligned fibers composed of extracellular matrix (ECM), a process called contact guidance. During contact guidance, aligned fibers bias migration along the long axis of the fibers. These aligned fibers of ECM are commonly composed of type I collagen, an abundant structural protein around tumors. In this paper, we epitaxially grew several different patterns of organized type I collagen on mica and compared the morphology and contact guidance behavior of two invasive breast cancer cell lines (MDA-MB-231 and MTLn3 cells). Others have shown that these cells randomly migrate in qualitatively different ways. MDA-MB-231 cells exert large traction forces, tightly adhere to the ECM, and migrate with spindle-shaped morphology and thus adopt a mesenchymal mode of migration. MTLn3 cells exert small traction forces, loosely adhere to the ECM, and migrate with a more rounded morphology and thus adopt an amoeboid mode of migration. As the degree of alignment of type I collagen fibrils increases, cells become more elongated and engage in more directed contact guidance. MDA-MB-231 cells perceive the directional signal of highly aligned type I collagen fibrils with high fidelity, elongating to large extents and migrating directionally. Interestingly, behavior in MTLn3 cells differs. While highly aligned type I collagen fibril patterns facilitate spreading and random migration of MTLn3 cells, they do not support elongation or directed migration. Thus, different contact guidance cues bias cell migration differently and the fidelity of contact guidance is cell type dependent, suggesting that ECM alignment is a permissive cue for contact guidance, but requires a cell to have certain properties to interpret that cue.

Interplay of RhoA and mechanical forces in collective cell migration driven by leader cells

The leading front of a collectively migrating epithelium often destabilizes into multicellular migration fingers where a cell initially similar to the others becomes a leader cell while its neighbours do not alter. The determinants of these leader cells include mechanical and biochemical cues, often under the control of small GTPases. However, an accurate dynamic cartography of both mechanical and biochemical activities remains to be established. Here, by mapping the mechanical traction forces exerted on the surface by MDCK migration fingers, we show that these structures are mechanical global entities with the leader cells exerting a large traction force. Moreover, the spatial distribution of RhoA differential activity at the basal plane strikingly mirrors this force cartography. We propose that RhoA controls the development of these fingers through mechanical cues: the leader cell drags the structure and the peripheral pluricellular acto-myosin cable prevents the initiation of new leader cells.

2A1-O04 空気圧駆動式3体節イモムシ型管内走行ロボット(特殊移動ロボット(1))

This paper deals with a new inspection robot imitating a green caterpillar. Gas or water pipes for individual or corporate houses and boilers or hot water pipes for industries are settled in the ground or in the narrow spaces and some of them are covered by casings or hard heat insulators. So, it is very difficult to inspect from outside of the pipe. However, we are easy to inspect the pipe from inside of the pipe. Conventional inspection robots imitating an earthworm and inchworm could not move in different diameter pipe and could not generate large traction force. The green caterpillar sticks a passage such as the leaf by its prolegs. The new inspection robot can move in the pipe whose diameters are from 70 mm to 100 mm, generating the traction force of 17.6 N.

20701 イモムシ型管内走行ロボットを構成する要素の一考察(OS7 ロボティックス・メカトロニクス(4),オーガナイズドセッション)

We have many small diameter pipes that are gas or water pipes for individual or corporate houses. They must be periodically inspected in order to protect the accident previously. We have proposed an in-pipe mobile robot that is imitated the waving motion of the green caterpillar. The robot is constructed by two somites and three suction brakes. The somites are imitated the waving motion driven by the pneumatic and the vacuum pressures. The robot was confirmed to move in pipes whose diameters are more than 70 mm. The robot is needed the large traction force in the case of the long pipe movement, because it must tow the pressure lines. Now, we investigated the traction force from the mechanisms of the robot. The traction force depended on the friction force of the suction brake and shrinking force of the somite. It was obtained 31 N.