Curve Tracking Research Articles

An Experimental and Numerical Study on Reduction of Generated Axial Force

This paper proposes an experimental and numerical study to reduce the generated axial force (GAF) in a tripod constant velocity joint (CVJ). Based on the GAF model developed through kinematic and frictional analysis on the tripod CVJ, the key parameters that have a significant influence on the GAF are obtained. These parameters vary with the design parameters of the CVJ and the optimal design parameter with the lowest GAF are presented. The GAF of a tripod CVJ is estimated by the developed model, with respect to various design parameters, and the results shows that track curvature highly affects the GAF whereas contact angle hardly affects the GAF. The GAF decreases with the decrease of track curvature, and the minimum GAF occurs at −20% track curvature and +20% contact angle.

Trajectory-Tracking Control for Manipulators Based on Fuzzy Equivalence and a Terminal Sliding Mode

To suppress the chattering of manipulators under heavy-load operations, a control method called fuzzy equivalence & terminal sliding mode (FETSM) was applied to the trajectory tracking of motion curves for manipulators. Based on the switching term of the equivalent sliding mode (ESM), a fuzzy parameter matrix processed by the simple fuzzy rules was introduced, and the fuzzy switching term was obtained. By summing the fuzzy switching term and the equivalent term of the equivalence and a terminal sliding mode (ETSM), the control law of the FETSM for manipulators was obtained. On this basis, the stability of the system was analysed and the finite arrival time of it was deduced. On the premise of ensuring the stability of the system, the fuzzy rules and membership functions were designed for the fuzzy constants in the fuzzy switching term. Simulation tests show that the proposed FETSM can ensure sufficient trajectory-tracking precision, error convergence speed, and robustness. Compared with the ETSM, the proposed FETSM can reduce the chattering time by 94.75 % on average; compared with the proportion-integral-differential (PID) control method, the maximum chattering amplitude by the FETSM can be reduced by at least 99.21 %. Thus, the proposed FETSM is suitable for those manipulators under heavy-load operations.

Fully Automatic Operation Algorithm of Urban Rail Train Based on RBFNN Position Output Constrained Robust Adaptive Control

High parking accuracy, comfort and stability, and fast response speed are important indicators to measure the control performance of a fully automatic operation system. In this paper, aiming at the problem of low accuracy of the fully automatic operation control of urban rail trains, a radial basis function neural network position output-constrained robust adaptive control algorithm based on train operation curve tracking is proposed. Firstly, on the basis of the mechanism of motion mechanics, the nonlinear dynamic model of train motion is established. Then, RBFNN is used to adaptively approximate and compensate for the additional resistance and unknown interference of the train model, and the basic resistance parameter adaptive mechanism is introduced to enhance the anti-interference ability and adaptability of the control system. Lastly, on the basis of the RBFNN position output-constrained robust adaptive control technology, the train can track the desired operation curve, thereby achieving the smooth operation between stations and accurate stopping. The simulation results show that the position output-constrained robust adaptive control algorithm based on RBFNN has good robustness and adaptability. In the case of system parameter uncertainty and external disturbance, the control system can ensure high-precision control and improve the ride comfort.

Formation Mechanism of Metro Rail Corrugation Based on Wheel–Rail Stick–Slip Behaviors

Field investigation shows that most corrugations occur on the inner rail surface of curved tracks with a radius of less than 700 m. In order to explore the formation mechanism of metro corrugation, the relationship between wheel–rail stick–slip characteristics and rail corrugation is studied by combining single wheelset curving and a rigid–flexible coupling model. The numerical results illustrate that the lateral torsional stick–slip vibration of inner rail–inner wheel of the guiding wheelset on the small radius curve eventually leads to the generation of inner rail corrugation, and the lateral torsional stick–slip vibration of outer rail–outer wheel of the driven wheelset may also occur, but the intensity is weak and the probability is low. The lateral torsional stick–slip vibration of inner rail–inner wheel of the guiding wheelset on the large radius curve is also easy to cause inner rail corrugation, but the degree of inner rail corrugation is lower than that on the small radius curve; the outer rail on the large radius curve is still not easy to produce corrugation. The formation mechanism of rail corrugation on the straight track is different from that on the curve track, which is mainly related to the wheel–rail longitudinal torsional stick–slip vibration.

Are weight shifting and dynamic control strategies different in postmenopausal women with and without type-I osteoporosis?

ObjectiveTracking postural control processes at dynamic conditions might help develop an appropriate rehabilitation program in osteoporotic women. This study aimed to investigate the differences in center of pressure (COP) control at weight shifting and dynamic tasks between postmenopausal women with and without type-I osteoporosis. Also, we investigated the correlations between bone mineral density (BMD), the activity-specific balance confidence questionnaire (ABC-Q) score, and postural control parameters. MethodA total of 62 volunteer postmenopausal women participated in this study. The participants were classified into non-osteoporotic (NOP, T-score >1, n = 35, age = 60.04± 5.33 years) and osteoporotic (OP, T-score < −2.5, n = 27, age = 61.88 ± 5.34 years) groups. The COP sway was recorded using a Kistler force plate during performance-based Limits of Stability (LOS), Curve Tracking (CT), Sit to Stand (STS), and Turn tasks. In addition, the level of balance confidence in daily activities was evaluated by ABC-Q. ResultsIn the LOS task, COP sway velocity in the anterior direction (P = 0.02) and COP maximum excursion in the side-to-side direction (right-side P = 0.027 and left-side P = 0.044) were significantly lower in the OP than the NOP group. In the CT task, all the quantified parameters, including errors and area, showed significantly lower values in the OP group than the NOP group (P < 0.05). In the STS task, the rising index score was significantly higher in the OP group than the NOP group (P = 0.014). The two groups had an equal ABC-Q score (P = 0.175). The COP sway variables correlated significantly with the lumbar and femoral neck T-score (P < 0.05). ConclusionBMD decline can change weight shifting and dynamic postural control in postmenopausal women.

MPC Based Trajectory Tracking for An Automonous Deep-Sea Tracked Mining Vehicle

Model predictive control (MPC) has been successfully used in trajectory tracking for autonomous vehicles based on certain kinematic model under low external disturbance conditions, but when there are model uncertainties and external disturbances, autonomous vehicles will fail to follow the pre-set trajectory. This paper studies trajectory tracking control based on MPC for an autonomous deep-sea tracked mining vehicle in polymetallic nodule mines with model uncertainty and external disturbances. A MPC algorithm is designed for trajectory tracking. To address model uncertainties caused by vehicle body subsidence and track slippage, a drive wheel speed correction controller is designed by experimental data fitting, and Kalman filtering (KF) and adaptive Kalman filtering (AKF) are introduced to improve tracking performance by rejecting external disturbances especially during curve tracking. To handle dead zones and obstacles during actual operation, an obstacle avoidance strategy is proposed that uses the tri-circular arc obstacle avoidance trajectory with an equal curvature for path re-planning. Finally, Simulink&amp;Recurdyn co-simulations validate the performance of the proposed MPC controller through a comparison with nonlinear MPC(NMPC).

Curve tracking and comparison during electricity spot trading based on judgment methods for curve similarity

Accurate tracking of load curves during transactions in the electricity generation process and timely identification and adjustment of aberrant electricity prices are key to ensuring profits from bidding in the production of enterprises. By selecting three judgement methods for curve similarity, i.e. Euclidean metric, correlation coefficient and mean square error (COE-MSE), and discrete Fréchet distance, this study tracked and compared an electricity generation curve, a transaction curve, and a bidding and declaration curve of a hydropower station where reservoirs have strong regulating capacity in a river basin in the Sichuan Province power grid. The advantages and disadvantages of the three methods were analysed and compared. The results demonstrate that the COE-MSE and discrete Fréchet distance can meet the requirements of electricity generation according to the transaction results when electricity generation enterprises participate in electricity spot trading. Furthermore, the discrete Fréchet distance shows advantages in identifying eigenvalues and tracking trends of the curves.

Experimental and Numerical Assessing the Lateral Resistance of Ballasted Railway Track Equipped with Mid-Winged Sleeper

Tendency of engineers toward continuous welded rails and its beneficial effects have raised the importance of lateral stability in railways. Small radius curves of tracks and temperature variations cause lateral force in tracks. There are different procedures to increase the lateral resistance of railway tracks. These methods are implemented using different materials by changing the size, geometry and dimensions of track components, especially sleepers. Although there are studies conducted on winged sleepers, utilizing mid-winged sleepers with modified geometry and dimension is considered in this research. Winged sleepers considerably increase the lateral resistance of tracks. However, some operational problems exist in its maintenance as the collision between wings of sleepers and tamping machine tines occurs. In this study, a number of experimental tests and numerical modeling were conducted on the lateral resistance of conventional and mid-winged sleepers. The lateral resistant force of tracks was measured by track panel loading test and single sleeper push test. The results revealed that by changing the conventional track to the mid-winged track, the lateral resistance increased considerably. The mid-winged panels tests, single mid-winged sleeper tests and numerical modeling indicate 58% to 64% increase in lateral resistance of mid-wing track compared with the conventional tracks.

Identification of the Major Noise Energy Sources in Rail Vehicles Moving at a Speed of 200 km/h

In this work, the problematic identification of the main sources of noise occurring from the exploitation of railway vehicles moving at a speed of 200 km/h were analyzed. Within the conducted experimental research, the testing fields were appointed, measurement apparatus selected, and a methodology for conducting measurements was defined, including the assessment of noise on a curve and straight track for electric multiple units of the so-called Pendolino, an Alstom type ETR610 series ED25 train. The measurements were made using a microphone camera Bionic S-112 at a distance of 22 m from the track axis. As a result of the conducted experimental research, it was indicated that the noise resulting from vibrations arising at the wheel-rail contact (rolling noise) was the dominant source of sound.

Analysis of the ‘dynamics of railway vehicles’ research field development using scientometric approach

The paper demonstrates the possibilities of a scientometric approach using CiteSpace II software analysis of the field of railway dynamics with detection of research front, main clusters of cross-cited papers, their evolution and pivotal points (see terms in Sections 2.1 and 2.2). The initial database contained 5126 Web Of Science records published between 1975 and 2019 (45 years). The linguistic analysis determined the evolution of burst terms and grouped the papers in 14 clusters that corresponded with the view of the specialists in the field. ‘Railway vehicle’, ‘Curved track’ (hunting stability and derailment risk), ‘Unconventional railway truck’, ‘Railway turnout (crossing)’ and ‘Polygonal wear’ clusters were analysed in more detail with a determination of top-cited papers in each cluster and papers that determined connections between clusters (pivotal papers). Two pivotal papers were verified with their authors.

On the Planning and Construction of Railway Curved Track

Increasing demand for railway vehicle speed has pushed the railway track designers to develop high-quality track. An important measure of track quality is the character of the transition curve track connecting different intersecting straight tracks. A good transition curve track must be able to negotiate the intermittent stresses and dynamic effects caused by changes in lateral acceleration at high speed. This paper presents the constructional methods for planning transition curves considering the dynamics of movement. These methods consider the non-compensated lateral acceleration, deviation in lateral acceleration and its higher time derivatives. This paper discusses the laying methods of circular, vertical and transition curves. Key aspects in laying a curved track e.g. widening of gauge on curves are discussed in this paper. This paper also suggests a transition curve which is effective not only from a dynamic point of view considering lateral acceleration and its higher time derivative but also consider the geometric conditions along with the required deflection angle.

An alternative frequency-droop scheme for wind turbines that provide primary frequency regulation via rotor speed control

This paper proposes a frequency-droop control scheme for wind turbines using rotor speed control. The control scheme is proposed as a better alternative to conventional frequency-droop control techniques. When conventional frequency-droop control is used, the frequency response produced by the wind turbine is dependent on the method of power tracking employed. When power tracking is achieved using torque control, the wind turbine’s frequency response is limited to short duration responses, even when operating reserve is available via de-loaded power tracking. This means that reserves cannot be fully utilised. When power tracking is achieved using power signal feedback, conventional frequency-droop methods under-deliver on the expected frequency-droop response due to rotor deceleration during frequency response. The proposed control scheme is unaffected by rotor deceleration and the method of power tracking employed as primary frequency regulation is achieved by varying the wind turbine’s power tracking curve, rather than adding droop control signals to the wind turbine’s power tracking reference. The effectiveness of the control scheme is validated through simulations using DIgSILENT PowerFactory. The results show that the control scheme produces the same frequency regulating response in wind turbines that achieve power tracking using torque control as those that use power signal feedback. This is an improvement on conventional frequency-droop control techniques and will improve the consistency and predictability of frequency regulating services procured from wind farms.

A track initiation method for radar target tracking based on B-spline curve interpolation

A novel efficient track initiation method based on B-spline curve interpolation is proposed. The framework of the proposed method is built based on a dynamic programming track-before-detect framework with B-spline curve interpolation. In order to effectively detect the target in the clutter area, B-spline curve interpolation algorithm is used to accumulate the energy of the candidate target along a valid curve rather than a straight line. The continuous smoothness of the B-spline ensures the continuity of the velocity acceleration of the track, and its locality enables the curve shape of the track to be adapted. Because the curvature of track curve is limited by dynamic overload, the curvature can be calculated by B-spline curve to limit the false track. Meanwhile, the measurement error of the radar system is used as a constraint condition. The experiment results show that the method proposed in this paper has better track initiation accuracy, lower error rate and faster detecting speed compared with several traditional track initiation algorithms.

On the permissible speeds of empty freight cars mounted on 18-100 model bogies

Problem of ensuring motion safety of empty freight cars is most acute in relation to cars on bogies of model 18-100, which is mainly due to operational wear of wheelsets, side frames and bolsters, as well as spring suspension elements. A potential threat to traffic safety arises when a train, composed of mostly empty and lightly loaded cars, moves along track sections that have deviations in the geometry of rail track of III and higher degrees or combinations and sequences of deviations of II degree. The article presents the main results of complex studies: mathematical modeling of the dynamic interaction of the track and empty freight cars of various types of bogie wear based on the Universal Mechanism software and field tests of cars on measuring sections of tangent, easement and circular curves with a radius of 350, 650, 800, 1000 and 2050 m on the section Belorechenskaya — Maykop of the North Caucasian railway. Dynamic qualities and motion stability of empty freight cars of various types are investigated depending on the parameters of the technical condition of the running gears and the deviations of the geometry of the rail track of II and III degrees of various types and combinations when moving in tangent and curved track sections. Authors provide tables and graphs of the dependences of indicators of dynamic qualities and motion stability of universal empty freight cars of various types on the motion speed in tangent sections of the track and circular curves of various radii and easement curves containing artificial deviations of the geometry of the rail track, most negatively affecting traffic safety. Recommendations are given for correcting the regulatory documents of the Russian Railways, which regulate the permissible speed of motion of empty freight cars, depending on the technical condition of the running gear.

A Machine Vision System Based on Driving Recorder for Automatic Inspection of Rail Curvature

Because of long distance of railway lines, it is difficult to find an appropriate method to inspect the rail track condition efficiently and accurately. In this article, a machine vision system based on driving recorder and image signal processing is proposed to evaluate the rail curvature automatically. The proposed machine vision system consists of four modules including the video acquisition module, the image extraction module, the image processing module, and the track condition assessment module. Three classic edge detection methods are adopted and compared for rail edge detection. In line with the videos of driving recorder, coordinate systems for train and rail are defined in the Lagrangian space, and the track curvature is estimated using the proposed chord offset method and double measurement method. For evaluating the track condition, an index describing the concordance between the train and track is defined. In the case study, a set of videos from the driving recorders of trains during their in-service operations are analyzed by the proposed technique, and the obtained results are verified by comparison with those obtained by a track geometry inspection vehicle. It is shown that the proposed technique can evaluate the track curvature accurately. Moreover, the influence of the position of deployed driving recorder, the focal length and anti-shake of camera on the accuracy of evaluation results is discussed. It is testified that the proposed technique provides a simple and reliable way to inspect the track curvature.

Determining the effects of non-catastrophic nail puncture on the operational performance and service life of small soft case commercial Li-ion prismatic cells

This work focused on the operational effects of Li-ion batteries (LIBs) that had been partially damaged and were allowed to continue operating afterwards. The intent was to simulate the operation of a damaged cell in an abusive environment, such as that found in electric vehicles and hybrid-electric vehicles. A test rig implementing a drop hammer with a nail attached was used to puncture approximately halfway through cycling LIBs to determine how their operation was affected. For all LIBs tested, the puncture caused a rapid spike in temperature. The dynamic impact immediately caused an initial drop in capacity of approximately 11%, and capacity continued to decrease throughout the remainder of the cycles. The cells also reached their end of life within an average of 43 cycles after the puncture, much sooner than the rated lifetime. Postmortem analysis of the punctured LIBs presented impact induced physical damage to the electrodes, oxidation of the electrolyte, and degradation of the interior components of the cells. This caused a decrease in discharge capacity and shortened useful lifetime due to hindering the charge capability of the cells. The degradation mechanism of the cells was further determined using peak tracking of the incremental capacity curves throughout their lifetimes.

Curved Ballasted Track-Vehicle Dynamic Interaction: Effects of Curve Radius and Track Structural Nonlinearity

Abstract In this work, a model for characterizing the ballasted track-vehicle interaction is presented. The vehicle is modelled as a multi-rigid-body system consisting of a car body, two bogie frames and four wheelsets, and the track is modelled by finite elements including the rail, the sleeper and the track bed. All bodies are connected by spring-dashpot elements. With novelty, the geometric nonlinearity of curved rail beam and mechanical nonlinearity of ballasted bed lateral resistance have been fully considered. Besides, numerical solution procedures including iteration and increment have been also developed to accurately clarify the dynamic nonlinear performance of vehicle-track systems. Apart from model validations in statics and dynamics, the influence of track nonlinearity and curved track radius on vehicle-track dynamic performance has been revealed in detail.

Accidents and injuries in elite MotoGP motorcycle riders

ObjectiveEvaluating incidence, characteristics and risk factors of accidents and injuries in each elite motorcycle racing class (MotoGP, Moto2 and Moto3), 2013–2017. DesignDescriptive epidemiological study. SettingMotoGP Medical Team, Dorna Sports SL. ParticipantsCompeting riders in elite motorcycling racing classes, 2013–2017. InterventionsBenchmarking incidence, characteristics and risk factors of accidents and injuries in each elite motorcycle racing class, 2013–2017. Main outcome measuresAssociation between accident type (by class and year) and fracture, withdrawal from race, need for surgery, injuries (fractures or contusions/wounds) and time riders kept inactive. Circuit and curve, weather conditions, presence and type of fracture, clinical outcome, and time until return to competition. Event outcomes were defined as rider fit/rider unfit after each accident. Racing class, track curves and circuits with the most and fewest accidents, circuit characteristics, speed and deceleration, G-forces, and time race differences between classes. Results9092 accidents (mean 1818,4 per year). Most during race and under wet-weather conditions. Class and circuit with most accidents 2013–2017 were Moto3 (3374; 37.11%) and MWC – Marco Simoncelli —with 430.119/9092 accidents resulted in a fracture (1.31%), 83, surgical fractures (70%). Most frequent surgical fractures were upper extremity (clavicular; 29/119; 21%). On average, riders returned to competition after two circuits (1–5 weeks). ConclusionsAccidents are not uncommon among elite motorcycle riders; incidences of fractures and surgical fractures are low. Factors such as weather conditions and circuit’s characteristics influence the risk of accidents. Further research is necessary to clarify the magnitude of the role each of these factors play.

Developing and testing a new quantitative near infrared spectroscopy online tracking measuring system for soil detection during automatic dishwashing

Near infrared (NIR) measurements have been used for several years to examine the processes taking place in the dishwasher during dishwashing. It is possible to differentiate between the soil components butterfat, oatmeal and egg-yolk and to determine their concentration in the dishwashing liquor quantitatively. Consequently, time-consuming dishwashing tests can be avoided by weighing the dishes. However, this method is also based on a small number of NIR measurements which are carried out intrusively during the dishwashing process, i.e. outside the dishwasher. These few NIR measurements make it difficult to investigate the dynamics of a dishwashing process. In this study, the development, testing and usage of a new online tracking measuring system is presented. The latter was used to perform 38 dishwashing processes, each containing 51 NIR spectra, to develop a calibration model using the partial least squares regression method with cross-validation. This new online tracking measuring system, based on the calibration, can determine the concentrations of three different soil components in the dishwashing liquor during automatic dishwashing. By recording the 51 spectra, it is possible to display a tracking curve for each soil component, i.e. the concentration courses of the dishwashing process over time. This results in a significantly better time resolution and it was possible to investigate the first dynamic part of the tracking curve, i.e. the beginning of the dishwashing process. This could lead to the opportunity to change the state of the dishwasher depending on the concentrations detected in the first step and, secondly, to a more environmentally friendly and cost-reducing dishwashing process.

Estimation of lateral track irregularity using a Kalman filter. Experimental validation

The aim of this work is the development of a model-based methodology for the estimation of lateral track irregularities from measurements from different sensors mounted on an in-service vehicle: a gyroscope to measure wheelset yaw angular velocity, two accelerometers to measure lateral acceleration of the wheelset and bogie frame, and an encoder to obtain forward velocity of the vehicle. The proposed methodology is based on the Kalman filtering technique, through the use of a highly simplified linear dynamic model of a bogie, capable of capturing the most relevant lateral dynamic behaviour of the entire vehicle. The simplified dynamic model (SM) is based on a vehicle running at variable forward velocity on a track, which comprises straight, curve and transition sections. Finally, the proposed methodology has been experimentally validated through an experimental campaign carried out in a 90 m 1:10 scaled track facility at the University of Seville and an instrumented scaled vehicle. The results of the estimation of the lateral alignment are analysed in the space domain and in the space frequency domain, according to standards. These results are promising, showing a good performance for monitoring lateral alignment on straight and curve tracks, with a very low computational cost. Only in the case of very sharp curves, when continuous flange contact takes place, the estimator is not able to precisely estimate lateral alignment.