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The control system for energy-efficient train operation with the inclusion of a detailed train motion model and train traction system energy efficiency is presented in the paper. A piecewise affine train model is constructed with the parameters obtained for the electromotive train of an industrial manufacturer. The model encompasses intrinsic features of the train system such as linearized resistance force, a set of traction and braking force physical limitations and passengers comfort constraints. The resulting quadratic optimization problem is solved parametrically through dynamic programming giving the off-line precomputed optimal control law that is a function of train speed and traversed path. The on-line computed traction force profile is then tuned with respect to the traction system energy efficiency. The developed control system is evaluated on a detailed real case study scenario put together with a railway operator and the train manufacturer. The presented results show the possibility of significant energy consumption reductions achieved by energy-efficient train control.

With the continuous development of rail transit industry and the acceleration of train speed, higher requirements are established for the operation quality of high-speed trains and the reliability of transmission system. In the process of train running, speed fluctuation and vibrations from various parts of the driving devices are common, which could be greatly affected by the traction torque. During traction transmission, the harmonic vibration torque exists in traction motor due to that the motor is connected with non-sinusoidal alternating current. In order to study the vibration influence of the electrical component of traction transmission system on the rail vehicles, i.e., bogie and car-body, an electro-mechanical coupling dynamic model for rail transit vehicles was established by explicitly incorporating the electric-induced traction into the transmission model. The dynamics responses of the vertical, lateral and longitudinal acceleration on vehicle components, such as axle box and car-body were quantitative analyzed. By comparison with field test, it was observed that there was a vibration peak of 12-times of the fundamental rotor frequency on the bogie frame and axle box, which existed at conditions of traction, uniform speed and braking. However, the vibration acceleration exhibit nearly little difference with or without traction force, especially at low frequency domain

A new traction force approach (TFA) for weld root fatigue analysis of complex cruciform connections is introduced. The approach defines the local nominal weld stress by using a solid element model and connecting the welded parts only from the toe and root lines. This enables the peak weld forces to be distinctly defined. The TFA approach was validated with a fully connected solid element model. As a comparison, the same analyses were performed for a shell element model. The study shows that the approach that is introduced here gives a good estimate for the local weld force with a maximum error of 10% while the commonly used shell element model greatly overestimates the peak weld force, particularly for complex connections. The analysis of fatigue-tested connections showed that by using TFA, instead of an approach based on overall nominal weld stress, the scatter range index is reduced from 3.71 to 1.98. The TFA approach is much more efficient compared to conventional approaches because of the low pre- and post-processing effort.

The article presents an analysis of the loading the milling working body of the disc cutting machine. The diagram of the current efforts on the working body of the disc cutting machine is presented. The process of loading a milling working body in a steady-state mode of movement is considered. It is established that in the steady state mode of operation of the cutter the feed force created by the weight of the working body and the force of the hydraulic cylinders of lifting and lowering will be equal to the resistance of movement along the y axis. The concept of an average cutter is proposed, its main characteristics are presented, the cutting angle, the back angle, the width of the wear site, the width of the cutter, the thickness of the cut chips, the angle of rotation. The diagram of the forces acting on the average cutter is presented, the thickness of the cut chips and the number of cutters installed on the working body are determined. It is established that the average cutter is affected by the force – caused by the action of the torque, and the result of the action of the traction force. These two forces determine the total active force. It is determined that the feed force is directly proportional to the area of the mill indentation and the number of cutters. The ground resistance to cutting, the resistance to moving the working body, and the feed force are considered. A system of equations is obtained that connects the components presented above. The torque and power generated by the drive for rotating the working body are determined.

Introduction. Farmers make extensive use of two-wheel tractors equipped with traction and drive interchangeable units. Two-wheel tractors are required to move evenly with minimal slip of the drive wheels on the soil. The tractive force on the drive wheels of the tillage unit is the decisive power factor in this case. An objective traction force value can be measured only by carrying out experimental studies. Materials and Methods. To determine the traction force on the drive wheels of the twowheel tractor, the design of the experimental stand was proposed and substantiated (RF patent for useful model No. 188610 “Movable module of the test stand”), and a methodology for planning and conducting a multifactor experiment to determine the traction force was developed. Results. As a result of the laboratory tests the calculation dependencies of the tractive force on the drive wheels of the Neva MB23-MultiAGRO Pro two-wheel tractor were obtained. Soil conditions, design and technological parameters, operating modes of the two-wheel tractor, and rolling resistance forces were taken into account. Discussion and Conclusion. The use of the developed regression models of the traction force under the condition of ensuring uniform movement with the minimum permissible slipping of the driving wheels of the two-wheel tractor on the soil will allow obtaining the permissible values of the two-tractor motion speed and form the zones of its most effective functioning.

In this paper an ecological adaptive cruise controller to reduce the fuel consumption and ensure the safe inter-vehicle distance for vehicles with step-gear transmissions is presented. An optimal control strategy using reinforcement learning with a novel actor-gear-critic architecture is proposed to obtain the continuous traction force trajectory and the discrete gear shift schedule. The traction force is determined from an actor network to maintain a desired inter-vehicle distance which improves the driving safety in a car-following process. The gear shift schedule is derived from a gear network to reduce the fuel consumption. The control strategy is model-free and allows continuous online learning for different driving situations without look-ahead velocity information. Particularly the nonlinear vehicle dynamics, the nonlinear transmission efficiency map for different gear ratios, and the nonlinear fuel consumption map are learned for fuel consumption reduction. The proposed controller is evaluated for different driving scenarios to demonstrate its robustness. Furthermore simulation comparisons for different gear shift schedules and velocity trajectories are given underling the advantages in terms of fuel economy and driving safety.

The traction force of a tracked unmanned ground vehicle (UGV) depends on the soil thrust generated by the shearing action on the soil-track interface. In the development of soil thrust, because the continuous-track system consists of a number of single-track systems connected to each other, interference occurs between the adjacent single-track systems through the surrounding soil. Thus, the total soil thrust of the continuous-track system is not equal to the sum of the soil thrust of each single-track system, and the interference effect needs to be carefully considered. In this study, model track tests were conducted on model single-, double-, and triple-track systems according to relative density of soil and shape ratio (i.e., the length of the track plate to grouser depth). The test results indicated that the interference effect reduced soil thrust due to the overlapping shear zones between adjoining single-track systems. The loss of soil thrust increased as the relative density of the soil increased and the shape ratio decreased. Based on these findings, a soil thrust multiplier that can be utilized to assess the soil thrust of a continuous-track system was developed.

The cone index (CI), as an indicator of the soil strength, is closely related to the traction performance of tractors. This study evaluates the traction performance of a tractor in terms of the CI during tillage. To analyze the traction performance, a field site was selected and divided into grids, and the CI values at each grid were measured. The CI maps of the field sites were created using the measured CI. The traction performance was analyzed using the measured traction load. The traction performance was grouped at CI intervals of 400 kPa to classify it in terms of the CI. When the CI decreased, the engine speed and tractive efficiency (TE) decreased, while the engine torque, slip ratio, axle torque, traction force, and dynamic traction ratio (DTR) increased. Moreover, the DTR increased up to approximately 13%, and the TE decreased up to 9%. The maximum TE in the DTR range of 0.45–0.55 was higher than approximately 80% for CI values above 1500 kPa. The DTR and TE results obtained in terms of the CI can help efficiently design tractors considering the soil environmental conditions.

Military operations usually include movement over existing roads and also through natural terrain. Wooded terrain is one of the most challenging environments which affect vehicle mobility. The ability of a vehicle to cross a forest area depends on the possibility of determining if the vehicle is able to manoeuvre between tree stems or can override individual trees. Overriding tree obstacles can be more effective if a vehicle needs a shorter time to cross some tree stems rather than manoeuvring around them. Vehicle movement to cross a forest stand depends on vegetation factors as the stem diameter, stem spacing, and also on tree root parameters, which determine the mechanical tree stability, and a vehicle’s ability to override the trees. Also, the technical parameters (width, length, turning radius, weight, traction force) of the selected military vehicle are important to classify the cross-country movement options. This study describes both the theoretical predictions of the movement of vehicles in forest stands and summarizes the results of one of the most extensive testing of vehicles’ ability to cross individual trees.

This article develops a new reconfigurable wheel composed of Six Adaptive Prisms (6AP). Then, an Unmanned Ground Vehicle (UGV) is established with four proposed wheels to investigate some primary t...

Differential steering is an emerging steering concept based on traction force differences between left and right sides of vehicles equipped with independently actuated wheels. Actually, this concep...

Recent studies have demonstrated that the power-cycling hydrodynamic mechanical (PCHM) transmission has excellent performance in improving power performance and fuel economy of a wheel loader. However, these results have been obtained by assuming that its speed ratio can always change continuously. Hence, this study first investigated the speed ratio of the transmission how to change when shifting from one gear to another. It was found that the concept of the PCHM transmission suggested in the literature is ineffective, even for a configuration with two gears in the gearbox. Then, the configuration of the PCHM transmission was developed as a different one to increase the torque multiplication capacity and efficiency of the transmission. A design method for this transmission is proposed to quantify its performances. The design method is based on a multi-objective optimization problem which is comprised of two objectives, seven design variables and eleven constraints. The relationships between average efficiency of the transmission and maximum tractive force of the vehicle and the seven transmission parameters are qualitatively examined. Results show that the performance of the transmission depends mainly on the number of transmission gears instead of on three parameters of the torque converter. The average efficiency is not sensitive to the maximum tractive force on a globally optimal Pareto front. The PCHM transmission with the new configuration can enable the average efficiency and the maximum tractive force to increase by 2.1 % and by 6.6 %, compared to that of the traditional hydrodynamic mechanical transmission, respectively.

Most of existing in-pipe robots are applied to de-fect inspection and regular maintenance, etc. There is al-most no in-pipe robot for big-diameter pipelines cleaningand are still problems of traction force and obstacle-overcoming. To deal with the problems, a novel wheeledand wall-pressing type in-pipe cleaning robot (IPCR) withhigh pressure water jet is proposed. Then the preloadmechanism, traction force, and obstacle-overcoming capa-bility of the IPCR are analyzed. The vibration equations ofthe simplified vibration system of the IPCR are established.Also, the necessity of preloading force is verified andmethods to improve obstacle-overcoming capability areproposed. Finally, the traveling capability is verified in adynamics simulation system. The simulation results showthat the proposed IPCR is powerful with traction force andhas a certain capability of obstacle-overcoming. Setting theattitude angle is zero and adding preloading force to allsprings can obviously weaken vibration of the IPCR.

The power on gear shift control of a parallel hydraulic hybrid vehicle (PHHV) is researched in this paper. A multibody dynamic model is built to capture the main vibration characteristics of PHHV powertrain, based on which the power on gear shift control strategy is designed and verified. To avoid the vehicle driving torque interruption during gear shift, power on gear shift control strategy is designed. In the control strategy, hydraulic pump/motor (HPM) compensates the engine torque when the engine clutch is disengaged for gear shift. The engine clutch engagement process is carefully controlled by LQR control strategy to mitigate the vehicle powertrain vibration and improve the vehicle driving comfort. Extended Kalman filter (EKF) is adopted to estimate the PHHV parameters required by LQR control. The available HPM torque depends on its working pressure which varies a lot with different accumulator state of charge. So the HPM torque compensation capability is investigated by analysing the traction force requirement during gear shift. To obtain the gear shift traction force demand, a gear shift schedule considering both vehicle fuel economy and dynamic performance is designed. The simulation results show that the HPM could satisfy most of the torque compensation requirements during gear shifts with the designed gear shift schedule in typical driving cycles.

Railway train energy simulation is an important and popular research topic. Locomotive traction force simulations are a fundamental part of such research. Conventional energy calculation models are not able to consider locomotive wheel–rail adhesions, traction adhesion control, and locomotive dynamics. This paper has developed two models to fill this research gap. The first model uses a 2D locomotive model with 27 degrees of freedom and a simplified wheel–rail contact model. The second model uses a 3D locomotive model with 54 degrees of freedom and a fully detailed wheel–rail contact model. Both models were integrated into a longitudinal train dynamics model with the consideration of locomotive adhesion control. Energy consumption simulations using a conventional model (1D model) and the two new models (2D and 3D models) were conducted and compared. The results show that, due to the consideration of wheel–rail adhesion model and traction control in the 3D model, it reports less energy consumption than the 1D model. The maximum difference in energy consumption rate between the 3D model and the 1D model was 12.5%. Due to the consideration of multiple wheel–rail contact points in the 3D model, it reports higher energy consumption than the 2D model. An 8.6% maximum difference in energy consumption rate between the 3D model and the 1D model was reported during curve negotiation.

Driving on ice is still a risky activity. Research has investigated the factors contributing to the friction mechanism and has reported experimental studies of pneumatic tyres on ice in order to develop models that predict tractive and braking performance on ice/snow. Therefore, developing testing methods to obtain relevant experimental data for the validation of models is equally important. There are agricultural and industrial vehicles which are also designed for pulling but there are no specific studies reporting experimental tests on traction force of such machines in snowy conditions. However, this issue is very topical, as demonstrated by the appearance on the market of winter tyres for such vehicles. This study presents a method for testing winter tyres in outdoor test facilities with a focus on traction performance. The conclusions will serve in future investigations as a concise knowledge source to develop improved testing facilities and tyre–ice interaction models, aiding the development of better tyre designs and improved vehicle safety systems. The functional tests hereafter described have been carried out with the aim of evaluating the possibility of measuring the influences of different technique solutions on the performance of certain 17.5 R25 sized industrial tyres.

This paper proposes a novel multi-wound differential pulley winch (MWDPW) component for assisting the ascending/descending operations of a wall climbing robot. The robotic platform enabling rope access in dangerous environments (ROPE RIDE) climbs vertical walls using a rope and embedded winch. The original winch installed on the ROPE RIDE was a single wound winch, which had problems such as rope slip, velocity ripple during descending motion, resulting the bad cleaning performance and unstable motion on the wall. These problems are mainly due to the concentration of traction force on the rope because a small portion of the winch pulley holds the entire weight of the robot. Therefore, we have developed a new winch, MWDPW, by using multi-wound differential traction pulley and pressure rollers to solve the traction force concentration problem by distributing the traction force along the entire wrapping angle. Compared to other multi-wound winches, the MWDPW has the special feature of a differential gear and pressure roller to distribute the traction force and minimize the rope slip. The tension of the MWDPW is analyzed using the basic capstan equation, and empirical results to minimize the rope slip are presented by varying design parameters such as the winding method and presence of the pressure rollers. We expect the proposed mechanism to improve the safety of a wall-climbing robot for wall-cleaning operations.

Purpose The traction behaviours of lubricating oil significantly affect the stability and lubrication regime of aviation high-speed ball bearings. Rolling elements will slide at a low traction force (TF). Therefore, traction behaviours need to be studied, and a fitting expression for traction curves to rapidly calculate the traction coefficient (TC) should be developed. Design/methodology/approach The traction behaviours of an aviation lubricating oil were studied in severe operating conditions with a self-designed two-disc testing rig. Based on the least squares method and the Levenberg–Marquardt theory, a rapid calculation expression was developed by fitting the obtained traction curves. The correction of this expression was experimentally verified by comparing the TCs under different operating conditions. This expression was also used to modify the commonly accepted quasi-dynamic model of rolling bearings. Findings An increase of the load led to an increase in the TC. In comparison, the temperature and entrainment speed showed inverse effects. The proposed expression exactly predicted the trend of the experimentally acquired traction curve. The calculation with the modified dynamic model showed that the action of the TF on a single rolling element varied and that the temperature increase of the outer raceway is higher than the inner raceway, which is caused by the TF and relative sliding speed between the elements and raceways. Originality/value The proposed fitting expression is able to simplify the TC calculation of synthetic aviation lubricating oil in practical engineering applications. This paper can provide an important reference for the traction behaviour of synthetic aviation lubricating oil under severe conditions and assist with its rapid calculation and practical application in engineering.

： Rovers are one of the most important vehicles used for conducting planetary exploration missions. On deformable terrain, traction is limited by the mechanical properties of the soil; therefore, a lack of traction and wheel slippage causes difficulties during operation of the rover. One possible solution for increasing the traction force is to increase the size of the wheel-terrain contact area. Flexible wheel forms can change depending on terrain conditions. So, flexible wheels exhibit high performance in traversing deformable terrain. However, the flexible metal wheel-terrain model for a planetary rover on deformable terrain has not yet been presented in detail. In this paper, a flexible metal wheel and a flexible wheel model that can quantitatively evaluate the sinkage and traction performance of flexible metal wheels on deformable terrain are designed. The theory has been built over the existing equations and validated with by test results. This paper establishes models for estimating static sinkage and dynamic wheel-terrain interaction mechanics. Experimental results from a single-wheel test show that the model can be used for mobility prediction with good accuracy. Based on the calculated model values and experimental results, the drawbar pull and torque of the flexible wheel clearly increases and sinkage clearly decreases compared with a rigid wheel of the same dimensions. The new model can be used to predict the traction performance of flexible wheels. This study can provide a reference for the flexible wheel design of planetary rovers.

In this paper, a new adjustable segmented wheel is proposed whose platform is composed of a complex closed-loop scissor mechanism wrapped over adjustable spokes. The new platform composed of four proposed wheels is specified to avoid halting, to increase traction force and to adjust body orientation while interacting soft or composite terrains. The soil contact model (SCM), extended from Bekker’s theory is implemented to derive the wheel-soil interaction formulations. Furthermore, the Lagrange approach is used to derive the unmanned ground vehicle (UGV) dynamics including interaction forces. The best configurations of adjustable wheel are tabulated according to the terrain properties and the motion types. Finally, the proposed UGV is compared with a typical ordinary UGV to investigate traction forces and halting avoidance. Based on the simulation results and primary tests of the experimental setup, it can be inferred that this new mechanism can effectively adapt itself to different terrain conditions in order to pass the soft concave regions, climb the soft obstacles and move on the composite terrains.

Purpose This study aims to evaluate the rheological properties of aviation lubricating oil under conditions of heavy load, high speed and high temperature and the applicability of the classical rheological model under severe conditions. Design/methodology/approach A Chinese aviation lubricating oil was used and its traction curves were obtained using a new two-disk tribotester. Its rheological parameters were calculated based on empirical formulae. Moreover, the traction force was calculated based on the classical Eyring rheological model. Findings The traction curves are obtained with respect to contact pressure, temperature and rolling speed. The rheological parameters are significantly influenced by environmental factors, especially viscosity. The traction force calculated using the Eyring model is consistent with the experimental results. Originality/value A novel two-disk tribotester was designed using a gas bearing and speed–force closed-loop control to ensure measurement accuracy. The mechanism of rheological properties was analyzed and the applicability of the classical rheological model under severe conditions was verified. It provided an experimental and theoretical basis for expanding the application of classical rheological models under extreme conditions.

Pipelines are important tools for transporting fluids. The regular use of pipeline robots to inspect pipelines is an important safety measure. Passive and active screw pipeline robots have been developed and have various characteristics. In this work, the structure and driving method of screw pipeline robots were introduced. An obstacle crossing model of active and passive screw pipeline robots was established and compared using the developed screw pipeline robots. A traction model of the active and passive screw pipeline robots that considers lateral and longitudinal slip characteristics was obtained. Then, the proposed pipeline robot traction model with lateral and longitudinal slips was verified through experiments. A traction experiment on the active screw pipeline robot with improved contact confirmed that an increase in the adhesion coefficient and reduction in driving wheel slip can increase traction force.

This paper presents a hypothetical conversion of a conventional heavy haul diesel-electric locomotive to its hybrid counterpart by incorporating a battery energy storage system. Starting from the basic parameters of a 1.6 MW diesel-electric locomotive currently found in the national railway company locomotive fleet, the quasi-static model of the locomotive is derived and validated. The conventional locomotive model is then converted to its hybrid counterpart by adding a battery energy storage system in parallel to the generator and equipping it with an adequate optimized energy management control strategy. The hybrid locomotive powertrain components are also appropriately re-sized in order to meet comparable traction force and power performance. Both the conventional and hybridized locomotive models are then used for the purpose of comparative analysis of main vehicle characteristics for the mountainous railway route driving scenario, which includes realistic slope and speed limitations. The obtained simulation results are used to gain insights about the possible advantages of the proposed conversion/drivetrain hybridization in terms of feasible reduction of fuel consumption and related CO2 emissions, while also considering additional hybridization costs and return-of-investment period.

Tractors and self-propelled harvesters are equipped with high volume pneumatic tyres with a low tyre inflation pressure. The contact patch can shift forwards or backwards in reference to the wheel centre as reaction on traction or brake forces because of the elastic tyre wall. Theoretical investigations – as necessary for modelling and simulation of dynamic vehicle behaviour – are complicated, since important tyre metrics cannot directly be measured based on the large deformations. Additionally, different definitions are often used. This is especially valid for the conversion of a drive torque into a traction force. In this context, the moment arm of the wheel load and the rolling radius of the tyre at zero slip condition are especially important. In contrast to the hitherto existing perception, the magnitude and position of the moment arm of the wheel load in reference to the wheel centre is dependent on traction and brake forces in addition to the motion resistance. The rolling radius of an elastic pneumatic tyre can be interpreted as radius of a fictitious rigid substitute wheel. This contribution emphasizes the outstanding importance of the rolling radius rdyn for all calculations on pneumatic tyres and the important roll of the variable moment arm of the wheel load for the moment compensation on the wheel.

The technological process of operation of a cylindrical bad-shaping roller of onion harvesting machine has been theoretically studied. The technological and design parameters of the cylindrical bad-shaping roller have been determined. They have a limiting effect on the operation of the machine for onion harvesting. They are diameter, width and rotational speed of the cylindrical bad-shaping roller, traction force, contact area and pressure of the cylindrical bad-shaping roller on the soil.

Complex pipeline network should be inspected regularly for safety. In general, these tasks are often completed by large pipe-climbing robots or customized equipment. Most of them are not effective, and cannot work on pipes with uncertain barriers. Moreover, some pipes are mounted in constrained scenarios, so bulky robots are not applicable. This paper presents a tethered soft-rigid pipe-climbing robot to fill the gap. Two indispensable actions, i.e. embracing pipe and moving along it, are realized by a soft component and a 3D printed wheel mechanism. The latter includes two forces: thrust force from the compressed air and tractive force from wheels, to drive the robot comprehensively, and a lightweight body (only 160g) benefits agile motion. In operation, pressure exerted on the soft component enables the robot to embrace pipes of different diameters, with controllable adhesion force, and locomotion force is also regulated. Inspired from vehicle, an elastic damper is attached between the wheel structure and the robot body, which can effectively alleviate vibration when crossing barriers. In addition, theoretical models are constructed to analyse and control thrust force, and the locomotion performance is analysed by dynamics model. Experiments demonstrate that this robot can perform rapid climbing at a speed of 1.09m/s in load-free scenarios, and it can move at a maximum speed of 0.828m/s with 500g load. Reconstruction of a flexible pipe using the robot is also demonstrated.

There is substantial motivation to develop novel adhesives which take advantage of the superior adhesive strength and adaptability of many natural animal adhesives; however, the tools typically used to study these mechanisms are incapable of determining the precise interactions of molecules at an adhesive interface. In this study, a surface specific, order sensitive vibrational spectroscopy called sum frequency generation (SFG) is, for the first time, combined with multiple bulk characterization techniques to examine a novel, simple biomimetic adhesive fluid inspired by tarsal fluid of insects. Insects perform complex adhesive demands, including sticking, climbing vertically and running upside-down with little difficulty. Thus, we hypothesize that both bulk and surface specific properties of the fluid contribute to the success of this wet adhesive mechanism. SFG spectra of biomimetic emulsion exhibited similar hydrocarbon organization on hydrophobic and hydrophilic substrates to natural beetle fluid previously studied with the same method (Fowler et al., 2021). Bulk characterization techniques indicated that the emulsion had a shear-thinning profile with the ability to enhance traction forces during climbing and low surface tension ideal for surface wetting on the majority of natural surfaces. Multi-technique comparisons between emulsion and pure squalane revealed that a hydrocarbon only based fluid could not replicate the traction promoting properties of the emulsion. We conclude that the insect tarsal fluid adhesive mechanism relies upon contributions from both surface-specific properties optimizing traction force and bulk properties promoting rapid surface wetting and maintaining pull-off force for fast detachment.

This article discusses the development of a method for assembling electromagnets based on the mutual influence of the magnetic characteristics of the parts. It also clarifies the term “complementary assembly” as more appropriate than “selective assembly” for this, as well as similar methods. For clarity, the model of the magnetic system is proposed to be considered in the form of an equivalent electric circuit, which allows you to concentrate on the most important factor affecting the final characteristic - the magnetic permeability of the material, or by analogy, presented in the form of magnetic resistance. The developed equivalent circuit, with the exclusion of effects that have less influence on the operation of the electromagnet, is a chain of series-connected resistors. The total resistance of these resistors must be kept constant to provide the closest possible output characteristic. The complementary assembly becomes possible by picking up the resistances of the resistors (which represents the magnetic properties of the real parts of the electromagnet) to get as close as possible to the required total resistance. Thus, the resistances of some resistors compensate for the deviation of the resistance of other resistors. The real influence of the magnetic properties of parts on the traction force was verified by the constructed experiment with statistical data processing.

The present study aims to provide a modified model for analysing the longitudinal dynamics of ground vehicles. Bearing in mind that an inevitable tire slip occurs under the transmission of driving torque to the drive wheels, the pure rolling assumption employed in many previous works is modified in this research. This paves the way through the development of a more realistic simulation framework with promising performance when used in vehicle and powertrain related topics. The modified equation of motion is an explicit function of tire slip ratio, and as a result, by rewriting the power balance equation, a dissipation term due to tire slip appears, which is consistent with the outcome of the recent contributions. Simulation results indicate a significant difference between the modified and simplified models in the case of a relatively high tractive force. Moreover, tire slip loss is obviously large in such a case, so that its neglect would lead to a noticeable inaccuracy in the response of the traditional model. An average of 35% improvement in the accuracy of prediction of tire consumed energy is observed in 0 to 100 km/h half-throttle acceleration manoeuvre using the modified model.

The following article covers the novel design of a linear flux modulating motor for direct-driven belt conveyors and gives an insight into considerations for manufacturing and system efficiency. In common approaches, belt conveyors are driven by attaching a geared electric machine to one of the drums, using the traction force between the drum and the belt to introduce linear motion. Since the contact area between the belt and the drum is small compared to the total belt surface, the achievable force in contact with the drum is limited. In order to increase the traction force between drum and belt, the tension inside the belt must be increased. The downside of this is higher mechanical stress and more complex belt designs to withstand the additional force. To overcome the mentioned aspects of common belt conveyors and to pave the way for new material flow models, a novel highly integrated direct-driven belt conveyor is presented. Efficient 3D FEM simulation results are provided, utilizing the symmetric properties of the motor to reduce simulation time considerably. In addition, an optimized design is presented resulting in a decreased force ripple and higher average force. Furthermore, an efficiency map for the desired operation range is given.

This paper reports a study into the possibility of using the chassis of combine-harvesters as a mobile energy device. The operational requirements for mobile energy technological devices for general purposes have been developed.The traction-coupling characteristics of the combine-harvester with an adapter that increases traction force have been investigated.The theoretical dependences have been derived of the motion speed, the power on a hook, the specific fuel consumption, as well as a factor of loading the wheels of the driven axle, on the traction force on the hook of an energy-technological device.It is noted that the use of the controlled axle with drive wheels reduces the slippage of the engines of the energy technological device. At the engine slippage level of up to 16 % an energy device, equipped with a driven axle with drive wheels, generates a traction force on the hook of up to 40 kN. Under the conditions of driving the axle by the hydraulic transmission mainline, the motion speed of an energy device decreases by 17.9 %, 28.5 %, 35.9 %, and 49.0 %, respectively, on gears I, II, III, and IV of the drive axle gearbox.The power on the energy device’s hook is increased due to the corresponding increase in traction effort: on gear III, at a traction effort within 35‒40 kN, the capacity on the hook is 68‒75 kW. Under these conditions, the specific fuel consumption is 430‒460 g/kWh at the device’s motion speed within 1.9‒1.95 m/s.The limits for changing the load factor on the wheels of the driven axle (not less than 0.2) have been determined, at which the requirements for control over an energy device are met.The specific fuel consumption (540‒580 g/kWh) by a combine-harvester with a throughput capacity of 9‒11 kg/s has been established, when using it as an energy technological device for general purposes at a motion speed of 1.7–2.1 m/s and a traction effort on the hook of 24‒33 kN, Исследована возможность использования шасси зерноуборочных комбайнов в качестве мобильного энергосредства. Разработаны эксплуатационные требования к мобильным энерготехнологических средствам общего назначения.Исследованы тягово-сцепные характеристики зерноуборочного комбайна с адаптером, который увеличивает его тяговое усилие.Получены теоретические зависимости скорости движения, мощности на крюке, удельных расходов топлива и коэффициента нагрузки на колеса направляющего моста от тягового усилия на крюке энерготехнологического средства.Отмечено, что использование управляемого моста с ведущими колесами уменьшает буксование движителей энерготехнологического средства. При уровне буксования движителей до 16 % энергосредство, оборудованое управляемым мостом с ведущими колесами, развивает тяговое усилие на крюке до 40 кН. При приводе моста от магистрали гидрообъемной трансмиссии скорость движения энергосредства уменьшается на 17,9 %, 28,5 %, 35,9 % и 49,0 % соответственно на I, II, III и IV передачах коробки переменных передач ведущего моста.Мощность на крюке энергосредства увеличивается вследствие соответствующего увеличения тягового усилия: на III передачи при тяговом усилии в пределах 35–40 кН, мощность на крюке составляет 68–75 кВт. При таких условиях удельные расходы топлива составляют 430–460 г/кВт ч при скорости движения средства в пределах 1,9–1,95 м/с.Определены границы изменения коэффициента нагрузки на колеса направляющего моста (не менее 0,2), при которых обеспечивается выполнение требований управляемости энергосредства.Установлено значения удельных расходов топлива (540–580 г/кВт ч) зерноуборочного комбайна с пропускной способностью 9-11 кг/с при его использовании в качестве энерготехнологического средства, когда скорость движения составляет 1,7–2,1 м/с, а тяговое усилие на крюке 24–33 кН, Досліджено можливість використання шасі зернозбиральних комбайнів в якості мобільного енергозасобу. Розроблено експлуатаційні вимоги до мобільних енерготехнологічних засобів загального призначення.Досліджено тягово-зчіпні характеристики зернозбирального комбайна з адаптером, що збільшує тягове зусилля.Отримано теоретичні залежності швидкості руху, потужності на гаку, питомих витрат палива та коефіцієнта навантаження на колеса напрямного моста від тягового зусилля на гаку енерготехнологічного засобу.Відмічено, що використання керованого моста з ведучими колесами зменшує буксування рушіїв енерготехнологічного засобу. За рівня буксування рушіїв до 16 % енергозасіб, обладнаний керованим мостом з ведучими колесами, розвиває тягове зусилля на гаку до 40 кН. За умов приводу моста від магістралі гідрооб'ємної трансмісії швидкість руху енергозасобу зменшується на 17,9 %, 28,5 %, 35,9 % та 49,0 % відповідно на І, ІІ, ІІІ та ІV передачах коробки перемінних передач ведучого моста.Потужність на гаку енергозасобу збільшується внаслідок відповідного збільшення тягового зусилля: на ІІІ передачі за тягового зусилля в межах 35–40 кН, потужність на гаку складає 68–75 кВт. За таких умов питомі витрати палива становлять 430–460 г/кВт∙год за швидкості руху засобу в межах 1,9–1,95 м/с.Визначено межі змінення коефіцієнта навантаження на колеса напрямного моста (не менше 0,2), за яких забезпечується виконання вимог керованості енергозасобу.Встановлено питомі витрати палива (540–580 г/кВт∙год) зернозбирального комбайна з пропускною здатністю 9–11 кг/с за умов його використання в якості енерготехнологічного засобу за швидкості руху 1,7–2,1 м/с та тяговому зусиллі на гаку 24–33 кН

Mathematical and computer models of the electric drive of electric vehicle for dynamic processes research in case of a decrease in the traction coefficient of wheels with the road and the occurrence of slipping have been created. The models take into account the presence in the kinematic scheme of the mechanical differential, the dynamic properties of the electric motor, the nonlinearity of the dependence of the friction coefficient on the wheel slip velocity. A computer simulation of the slipping processes has been made while driving on a horizontal road, when starting and overtaking with a run over a section of reduced grip with one wheel, as well as driving downhill to a similar area with two wheels. The analysis of time diagrams has shown their full compliance with the physical concepts and laws explaining the processes, and confirmed its adequacy. This allows us to consider these models as basic for studying the processes of slipping with various types of electric motors, electric drives systems, methods of control, as well as conditions of adhesion deterioration. Such researches may allow generalized conclusions to be drawn when creating systems for the implementation of maximum traction force and microprocessor control in case of an emergency.

In robot teaching for contact tasks, it is necessary to not only accurately perceive the traction force exerted by hands, but also to perceive the contact force at the robot end. This paper develops a tandem force sensor to detect traction and contact forces. As a component of the tandem force sensor, a cylindrical traction force sensor is developed to detect the traction force applied by hands. Its structure is designed to be suitable for humans to operate, and the mechanical model of its cylinder-shaped elastic structural body has been analyzed. After calibration, the cylindrical traction force sensor is proven to be able to detect forces/moments with small errors. Then, a tandem force sensor is developed based on the developed cylindrical traction force sensor and a wrist force sensor. The robot teaching experiment of drawer switches were made and the results confirm that the developed traction force sensor is simple to operate and the tandem force sensor can achieve the perception of the traction and contact forces.

In plant process pipelines, it is necessary for locating defects appears because of corrosion, cracks, etc. creating hurdles at inside circumference of pipeline. In spite of this, deterioration anyway takes place reducing overall toughness of pipeline. If it has been unnoticed and happen to be critical, pipe may develop leakage getting rupture involving serious damage. Several methods have been reported by researchers to mitigate these defects. However, an innovative method is proposed for carrying out an inspection of inner circumference of pipelines. An inspection robotic arm having active pipeline diameter approachability with automated adjusting tractive force has been designed and implemented for scrutiny of longer length major pipelines having various diameters. Robots dimensional design consider a schematic comprising 3 sets of parallelogram wheeled leg mechanism circumferentially spaced out 120° apart symmetrically. Such design structure permits possibility for realizing compatibility to pipe inner circumference together with adjusting tractive force. Based on evaluating mechanical movements for adaptation to pipe inner circumference, suitable mechanical models have been configured and their control circuit hardware including control topology has been described. To check compatibility and adjustments inside the process pipeline, prototype robot has been developed and field experiments have been performed in process pipeline. The experimentation data matching with theoretical analysis has been presented. Mobile robot is used for visual inspection as well as conducting non destructive testing for monitoring inner surface defects, cracks, corrosion, ageing and wall thickness of main pipeline. Using mobile robot, several types of flaws in the pipelines have been detected and categorized using variety of algorithms. Hardware results also have been presented.

This paper presents a tractive force estimation method for a hybrid PM-electromagnetic suspension system within a maglev train prototype. The main structure of the levitation system consisted of levitation cores, levitation coils, and inserted permanent magnets installed on both sides of the train. The key variable affecting tractive force were magnetic flux density from the levitation coils and permanent magnets, the cross section of the levitation cores, and the permeability of air gaps. To estimate traction force, the magnetic circuits of the levitation systems were first analyzed accounting for air gap variation as a results of total train weight, as tractive force across air gaps would need to balance the weight of the train. The simulations were carried out using a finite element analysis (FEA) program with constant air gaps of 10mm, at which permanent magnets were installed. The simulation and estimation results were compared to verify the accuracy of the proposed estimation method.

Based on compressive and shearing rheological models of the deep-sea sediment simulant, new rheological calculation formulae of traction forces for actual track shoe structures were deduced and the...

The force control of an industrial robot, as a significant control strategy, enables a robot to perform contact assignment or be guided by humans in free space. The existing six-dimensional force sensors installed at the end of manipulators own only one perceptual unit, which fail to detect the traction force given by one's hands accurately when the end effector contacts with the manipulated objects. In this study, a six-dimensional traction force sensor has been developed to measure the traction force, based on which a tandem type force sensor that can detect the traction force and contact force simultaneously is proposed. The tandem type force sensor consists of a general six-dimensional force sensor, which is used to measure the contact force between the end effector and the manipulated objects, and a six-dimensional traction force sensor, which is used to measure the traction force exerted by one's hand. The basic structure of the six-dimensional traction force sensor is designed, and the calibration experiment verifies the six-dimensional traction force sensor performs well.

Walking on natural terrain like soil and rock is a challenging problem that has been approached from a variety of strategies such as using sophisticated control methods, compliant legs, and compliant feet. In this paper we explore how to modify granular jamming feet for walking applications by adding stabilizing internal structures. Previous work has explored how granular jamming technology can be used to create compliant and stiffness changing feet that enable locomotion over a diverse range of natural terrain by allowing robot feet to conform around 3D multicomponent terrain such as wood chips and gravel and stiffen, preventing slip. To date, no work has been done to tune granular jamming feet for the specific application of walking. We show that adding internal structures to granular jamming membranes can increase the force they are able to resist without slipping by 1.5x while maintaining their ability to conform around obstacles. When attached to a robot, we see increases in speed of up to 1.4x, decreases in the duty cycle necessary to reach desired foot trajectories of up to 5%, and increases in traction force of up to 1.2x over a diverse set of natural terrain.

All-Terrain Vehicle (ATV) faces many drastic challenges in off road environment. Under those condition , one of the most challenging situation is that the rear wheel get struck in mud, but the Traction force make the rear wheel to get rid of mud. But, there is no such arrangement in front wheel so as to get rid of mud. To make the wheel to get rid of mud it requires, external efforts. Considering these constrain a novel idea that a modification in the design of wish bone has been done so as to adjust the camber angle, in transverse motion in the suspension system thus problem has been rectified.

Theoretically, there is zero slip between two bodies when there is no relative motion in their contact points. In the contact between a wheel and a surface, zero slip can be obtained only in the case of a single contact point. In this case, the wheel and the surface must be rigid. The theoretical zero-slip condition can’t be obtained in the contact between tire and terrain surface. In much of the scientific literature, two alternatives are suggested for a practical definition of the zero-slip condition: the point at which the gross traction force is equal to zero, or the point at which the net traction force is equal to zero. In the ASABE (2013), there is still no unique definition for the practical zero-slip condition. According to the definition of zero-slip condition, the rolling radius is not constant and depends on the slip. A detailed finite-element model using Lagrangian elements was built for each tire, taking into account the effect of all tire materials and their arrangement, lug shape, and inflation pressure. The soil model was built with Eulerian elements, which allow a large degree of deformation and flow of the soil. The initial verification experiments of the tire models were conducted by pressing the tires against a rigid plane. Each tire was examined under several different inflation pressures. Very good correlations were obtained between the experimental and model results. The verification test for the gross and net traction forces was performed in the soil-bin laboratory at the Technion. Special equipment was built, including a heavy dragging platform and a cell to hook the tire. This equipment allows control of the tire slip. The net traction force, gross traction force, and vertical load were measured in each test. Good correlations were obtained between the experimental and model results. Using the FEM model developed, some definitions for zero-slip condition were examined. The results indicate that the best criterion for zero-slip condition is definition of the point at which the gross traction force is equal to zero.

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.

The track system is generally applied for heavy off-road vehicles. While moving on the off-road, the track system horizontally transmits an engine torque to the soil-track interface, resulting in slip displacement and an associated soil thrust acting as a traction force. As soil thrust is developed on the bottom and the side of the track system (hereinafter referred to as “bottom thrust” and “side thrust”, respectively), it is imperative to evaluate both the bottom thrust and the side thrust to assess the off-road tracked vehicle’s performance. Unlike the bottom thrust, however, the mechanisms of the side thrust have not been fully understood. To address this, this study aimed to evaluate the side thrust for off-road tracked vehicles. A new mechanism for the side thrust was theoretically investigated based on the punching shear theory. A series of model track experiments were conducted on a model track system with silty sand. From the experiment results, the shapes of the failure surface were observed, and the side thrust was measured for verification purposes. Particular attention was given to the development of a side thrust prediction model for the heavy off-road tracked vehicles based on the proposed mechanism.

This research proposes a new extendable platform for an unmanned ground vehicle to overcome the obstacle climbing issue. The new platform is basically established on scissor mechanism principles which have been innovated to achieve long and rigid displacement. A couple of scissor mechanisms are embedded in the rover platform adjusting the mass center of rover respect to the rear and front wheels. Accordingly, it yields geometric control of the contact forces, which can simultaneously reduce the slip of the wheels and increase the performance of the obstacle climbing up. To demonstrate the performance of the proposed platform, the 3D kinematics is derived. Subsequently, the stick-slip Euler-Lagrange dynamics is derived and a three-level controller including the torque optimization is implemented to simulate the rover facing obstacles. Finally, without any hardware prototyping, the extendable rover is simulated and compared with a typical fixed-geometry rover to show the enhancement of the climbing ability by using the proposed concept. Moreover, controlling the normal contact forces of the wheels yields the slip reduction, which subsequently, increases the traction force.

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.

Preoperative skin sterilization, disinfection, and fracture reduction are all necessary for surgeries of the fractured lower extremity. This procedure requires several medical personnel, even though its tasks are relatively simple. Therefore, development of an assistant device for the preoperative disinfection and the simple fracture reduction is required as an alternative. To obtain the design specifications of the equipment, we evaluated lifting and traction forces using the lower extremities of Korean fresh cadavers. The lifting force was measured when each leg was lifted from the table using 39 Korean fresh cadavers. The same method was applied to measure the traction force on a femoral fracture model using 22 Korean fresh cadavers. The mean lifting force was 36.8 ± 11.8 N, and the mean traction force was 116.8 ± 37.9 N. Regression analysis yielded the following equations: lifting force = 0.6724*(body weight) - 0.8068, R2 = 0.71; traction force = 1.6880*(body weight) + 18.1495, R2 = 0.57. This study determined the lifting and traction forces, not just the body segment weights. These results will be helpful for developing medical assistant devices.

Tractors, the primary component of agricultural mechanization, are actively used for maintaining agricultural activities and carrying burdens on agricultural fields under challenging conditions. Tractors are not only required to possess a high tractive force at low operating speeds but also to produce the power necessary for operating the equipment attached to them when used for agricultural purposes. It is of great importance to determine the degree of force that powertrains, especially the clutch, of the tractors are exposed to on agricultural fields and to use the data obtained in this process concerning their guarantee periods. This study measured the motor rotation speed, clutch surface temperature, and frequency and force of pushing the clutch pedal of a tractor used under five different agricultural field conditions. Furthermore, torque and transfer of the dynamometer and power take-off (PTO) were measured. Based on the data obtained from field tests, the tractor clutch development and validation processes were revised. The prototype clutch was produced and tested by completing the required 1 million rotations safely under new boundary conditions within the guarantee period.

The negative impact of non-uniformity of current distribution in the power circuit of a freight direct current rolling stock on its operation efficiency was experimentally established. In contrast to existing approaches, the presented study reveals the entire range of factors that together affect non-uniformity of current distribution. The method of calculation of comprehensive influence of structural, technological and operational factors on current distribution was developed. It made it possible to determine conditions of elimination of the difference of currents and to increase traction properties of locomotives when controlling freight trains. The proposed coefficients allow analyzing the effect of various factors on current distribution and relationship between parameters of motors, connected in parallel. They visually show that deviation of currents at interaction of a locomotive with freight wagons affect not only particular parameters of wheel-motor units, but also their connection. The merit of this approach is the possibility of evaluation of non-uniformity of current distribution depending on the structure of electric machines and connection of structural parameters of a wheel-motor unit. Results of the study can be used during repairs of freight direct current rolling stock and in designing automatic control systems.

We have established the laws of change in the vehicle acceleration time at the existing step transmission of ICE, when implementing the total traction force, boundary for the drive wheels adhesion to the road, and during implementation of the proposed rational law for acceleration control. To model ICE speed characteristics, we applied the empirical dependence by S.R. Leyderman. The analytical expressions obtained allow us to implement such a change in vehicle acceleration depending on its speed that makes it possible to ensure maximum dynamism at minimal engine power consumption, taking into consideration a nonlinear change in external resistance. The maximum acceleration, which is possible to implement using the rational dynamic characteristic, can reach 7 m/s 2 . Based on the dependences obtained, it is possible to determine effective work of ICE required to accelerate a vehicle at different gears. An analysis of calculation results revealed that the transition from lower to higher gears is accompanied by a sharp decrease in engine energy expenditure required to accelerate the vehicle. It was established that for the case of hybrid vehicles, acceleration using the electric drive, rather than accelerating at lower gears of the mechanical drive, makes it possible to reduce energy losses by 20 % (for a four-cylinder internal combustion engine). Energy preservation is accomplished by reducing the fluctuation of traction force, as well as the possibility of a step-free change in motion speed.