Running Dynamics Research Articles

Development of a Design Procedure Combining Topological Optimization and a Multibody Environment: Application to a Tram Motor Bogie Frame

Nowadays, it is essential to find increasingly rapid and efficient design strategies. This approach becomes crucial in the railway industry, where components must be verified according to multiple reference standards, both structurally and dynamically. In this context, the present research activity aims to develop a fast and effective desin procedure based on European reference standards. The goal was to develop the geometry of a motor bogie frame for a tram vehicle, integrating three fundamental tools for development: finite element simulations and topological structural optimization, a Write Computer Aided Design (CAD) environment, and a multibody environment. Their integration could enhance design accuracy, streamline the traditional design workflow, and support innovation. The optimization process involved the introduction of complex technological constraints, directing the geometry toward production by casting. A tool was developed to automate running dynamics simulations and the output of results for immediate verification of the entire vehicle performance. Finally, the new geometry was tested both structurally and dynamically. The mass was reduced by approximately 7% while ensuring satisfactory mechanical performance. The maximum value of stress was reduced by about 16%. The dynamic performance showed negligible variation, confirming the encouraging outcomes to make this procedure increasingly effective and reliable.

Influence of the Beiring Sorenson Hold and the Barbell Back Squat on Running Cadence in Military Ruck Marching: A Cross-Sectional Observational Study

Ruck marching is a key performance indicator for tactical preparation; however, marching under load causes changes in biomechanics, which can increase injury risk. Although this risk of injury from changes is known, current methods commonly used for assessing physical fitness have not adequately identified how to minimize these changes. In this observational study, 14 ROTC cadets underwent a series of physical muscular fitness tests prior to performing a six-mile ruck march. These included an evaluation of postural endurance via the Biering Sorenson hold, lower body strength via the back squat, and upper body strength via bench press. After the tests were performed, ruck march performance was evaluated by total time to completion and running dynamics. Multiple regression analysis was performed to determine if bench press maximum, back squat maximum, or Sorenson hold were predictors of the performance of the ruck March. Average cadence shared a positive significant relationship with the Sorenson hold (r = 0.76, p = 0.02) and a negative significant relationship with the back squat (r = -0.76, p = 0.02). Additionally, the Sorenson hold did not share any significant relationships with total ruck time (r = -0.3, p = 0.29) or ground contact time (r = -0.41, p = 0.31). The back squat did not share significant relationships with ground contact time (r = -0.37, p = 0.37) or average smoothness (r = -0.38, p = 0.31). This study highlights the potential relationship that the Sorenson hold and back squat can have on running cadence, which has shown significant changes in previous research evaluating the changes in running performance and characteristics from weight ruck marching. Further investigation of the relationship of these assessments on the performance of ruck marching should be performed with larger numbers of cadets in the future.

Vertical and Lateral Dynamics of 4L Freight Bogie

Freight wagons in Europe have used Y25 bogies since the 1960s. Although very cost-effective, Y25 suffers from intrinsic limitations due to its architecture and running behaviour. This study introduces an innovative lightweight bogie, named 4L bogie, aimed at removing those limitations as well as improving running dynamics and track friendliness. This task was particularly challenging as the high ratio between laden and tare weight (up to 5:1) forced us to use a non-conventional suspension system and an innovative architecture of frame, reducing the mass by about 15% and the yaw moment of inertia by about 30% with respect to the Y25 bogie. Maintenance issues were addressed by reducing the number of components and easing overhaul, while the new design was validated from both the structural and the running dynamics point of view, assessing its interaction with the track in terms of stability, curving behaviour and the vertical response of the 4L bogie. Stability was improved by about 20% even in empty conditions and high conicity at the wheel/rail contact. Vertical dynamic force on a straight track, evaluated according to the Ride Force Count metric, and wear behaviour on sharp and mild curves were considerably reduced, leading to an improved track friendliness of the bogie.

Analysis of Kinematic Variables According to Menstrual Cycle Phase and Running Intensity: Implications for Training Female Athletes

Depending on the phase of the menstrual cycle, different values of running kinematic variables can be obtained. The aim of this study is to analyze whether there are changes in the kinematic variables in running throughout the menstrual cycle and to relate them to running performance and injury prevention. Eight regular female runners and triathletes performed a maximal treadmill test, as well as a submaximal test (6′ stages at 50%, 60% and 80% of maximal aerobic speed) in each of the phases of the menstrual cycle: menstruation phase (day 2.4 ± 0.7), follicular phase (day 10.4 ± 2.2) and luteal phase (day 21.8 ± 2.1). Running dynamics were measured using RunScribe. For parametric data, a general linear model of repeated measures was applied, with two intrasubject independent variables, menstrual cycle phases (with three levels: Menstruation, Follicular, and Luteal) and running intensity (with four levels relative to the maximum speed reached in the test: 100%, 80%, 60%, and 50%). For variables with non-normal distributions, Friedman tests were performed with Wilcoxon post-tests adjusted for significance according to Bonferroni. The maximum stance velocity from foot strike to the point of maximum pronation (°/s) was higher in the menstruation phase than in the follicular and luteal phases (p = 0.008), the step rate (s/min) was higher in the follicular phase than in the menstruation and luteal phases (p = 0.049), the vertical velocity (m/s) was lower in the follicular phase than in the menstruation (p = 0.004) and luteal phases (p = 0.003), and the contact time (ms) was lower in the luteal phase than in the menstruation and follicular phases. These results suggest that training at high intensities could be a factor in greater risk of injury in female athletes, especially in the menstruation phase, finding in the luteal phase and at an intensity of 80% a greater efficiency in the running.

Restricted antennal movement impacts the tandem running dynamics in a ponerine ant

BackgroundTandem running is a recruitment method found in some species of ants where one ant follows another ant to reach a destination having maintained a physical contact with its antennae, throughout the journey. It is considered that the exchange of information regarding the destination among the nestmates happened during the process of tandem running. We examined the impact of restricting antennal movement on tandem running by using Diacamma indicum, a tandem-running ponerine ant by following 480 tandem runs across 9 treatment colonies and comparing it with 10 control relocating colonies.ResultThough all the 19 colonies relocated successfully, treatment colonies took significantly longer time to do so. Restricted antennal movement did not influence the ability to become tandem leaders, initiate tandem runs or the work organization significantly. However, antennae-restricted ants performed fewer tandem runs and took significantly longer time. Followers with single or both antennae-restriction performed significantly higher number of interruptions and the alignment between the leader and follower was impacted as antenna-restricted followers subtended a greater angle and walked more to the side of the leader as compared to the control followers.ConclusionThis study showed unhindered movement of the followers’ antennae is important for tandem-running ants. In the next step, to gain a comprehensive understanding of this recruitment method, it is essential to individually delineate different sensory modalities.

ОБОСНОВАНИЕ РАЦИОНАЛЬНОЙ КОНСТРУКЦИИ КРИВОШИПНОГО МЕХАНИЗМА КОЛЕСНО-ШАГАЮЩЕГО ДВИЖИТЕЛЯ

The article substantiates the rational design of the crank mechanism of a wheel-step mover. Kinematics analysis of a prototype of the wheel-step mover revealed the presence of oscillations in the vertical coordinate of the central axis during movement. To eliminate this drawback, differential geometry methods were used, thanks to which a method for calculating the non-circular profile of support shoes was created. Studies of the dynamics of the crank mechanism of the wheel-step mover showed that even in a steady state of motion, periodically acting inertial forces arise. To reduce their effect, non-circular gears should be used in the mover power drive. The dimensions of the crank mechanism links have been calculated, at which the cross-country ability of the running system, its kinematics and dynamics characteristics are improved, energy costs when laying a track are reduced, as well as the negative impact of the machine on the fertile soil layer. The polar coordinates of the involute points have been calculated. They are needed to construct the tooth profiles of non-circular gears. As the power drive of the crank mechanism, non-circular gears have symmetrical geometric parameters along two axes and provide a constant movement speed. Thus, the wheel-step running system can be used in agriculture, the timber industry, mining, and when working in emergency situations. The mover design being developed is intended for unmanned ground vehicles. This type of unmanned vehicles is at the initial stage of its development, inferior in frequency to air and marine unmanned vehicles. A targeted concentration of production and financial resources is necessary to ensure that domestic industry has a leading position in the production and sale of unmanned ground vehicles.

Kinetic, Physiological and Fatigue Level Differences Depending on the Menstrual Cycle Phase and Running Intensity

Background: Depending on the phase of the menstrual cycle an athlete is in, some kinetic, physiological, and fatigue variables will show differences. The aim of this study is to analyze whether there are changes in these variables over the course of the menstrual cycle. Methods: Eight regularly practicing women runners and triathletes performed a maximal treadmill test and a submaximal test (6′ stages at 50%, 60%, and 80% of maximal aerobic speed) in each of the phases of the menstrual cycle: bleeding phase (day 2.4 ± 0.7), follicular phase (day 10.4 ± 2.2), and luteal phase (day 21.8 ± 2.1). Running dynamics were measured (using RunScribe) at the end of each test, as were lactate concentration, heart rate, and fatigue (evaluated on a scale of 0–5). Results: Higher shock (G) values were recorded in the bleeding phase (η2 = 0.27) and higher vertical spring stiffness (kN/m) was recorded in the follicular phase (η2 = 0.25). The phase of the menstrual cycle had a significant effect on average and peak heart rate, which was significantly higher in the follicular phase (η2 = 0.45 and η2 = 0.48, respectively). Conclusions: Higher vertical spring stiffness was observed in the follicular phase, in addition to higher peak and average heart rate.

The Validity of a Three-Dimensional Motion Capture System and the Garmin Running Dynamics Pod in Connection with an Assessment of Ground Contact Time While Running in Place.

A three-dimensional motion capture system (MoCap) and the Garmin Running Dynamics Pod can be utilised to monitor a variety of dynamic parameters during running. The present investigation was designed to examine the validity of these two systems for determining ground contact times while running in place by comparing the values obtained with those provided by the bilateral force plate (gold standard). Eleven subjects completed three 20-s runs in place at self-selected rates, starting slowly, continuing at an intermediate pace, and finishing rapidly. The ground contact times obtained with both systems differed significantly from the gold standard at all three rates, as well as for all the rates combined (p < 0.001 in all cases), with the smallest mean bias at the fastest step rate for both (11.5 ± 14.4 ms for MoCap and -81.5 ± 18.4 ms for Garmin). This algorithm was developed for the determination of ground contact times during normal running and was adapted here for the assessment of running in place by the MoCap, which could be one explanation for its lack of validity. In conclusion, the wearables developed for monitoring normal running cannot be assumed to be suitable for determining ground contact times while running in place.

The validity and reliability of wearable devices for the measurement of vertical oscillation for running.

Wearable devices are a popular training tool to measure biomechanical performance indicators during running, including vertical oscillation (VO). VO is a contributing factor in running economy and injury risk, therefore VO feedback can have a positive impact on running performance. The validity and reliability of the VO measurements from wearable devices is crucial for them to be an effective training tool. The aims of this study were to test the validity and reliability of VO measurements from wearable devices against video analysis of a single trunk marker. Four wearable devices were compared: the INCUS NOVA, Garmin Heart Rate Monitor-Pro (HRM), Garmin Running Dynamics Pod (RDP), and Stryd Running Power Meter Footpod (Footpod). Fifteen participants completed treadmill running at five different self-selected speeds for one minute at each speed. Each speed interval was completed twice. VO was recorded simultaneously by video and the wearables devices. There was significant effect of measurement method on VO (p < 0.001), with the NOVA and Footpod underestimating VO compared to video analysis, while the HRM and RDP overestimated. Although there were significant differences in the average VO values, all devices were significantly correlated with the video analysis (R > = 0.51, p < 0.001). Significant agreement between repeated VO measurements for all devices, revealed the devices to be reliable (ICC > = 0.948, p < 0.001). There was also significant agreement for VO measurements between each device and the video analysis (ICC > = 0.731, p < = 0.001), therefore validating the devices for VO measurement during running. These results demonstrate that wearable devices are valid and reliable tools to detect changes in VO during running. However, VO measurements varied significantly between the different wearables tested and this should be considered when comparing VO values between devices.

Comparison of leg dynamic models for quadrupedal robots with compliant backbone

Many quadrupeds are capable of power efficient gaits, especially trot and gallop, thanks to their flexible trunk. The oscillations of the system that includes the backbone, the tendons and musculature, store and release elastic energy, helping a smooth deceleration and a fast acceleration of the hindquarters and forequarters, which improves the dynamics of running and its energy efficiency. Forelegs and hindlegs play a key role in generating the bending moment in the trunk. In this paper we present our studies aimed at modeling and reproducing such phenomena for efficient quadrupedal robot locomotion. We propose a model, called mass-mass-spring model, that overcomes the limitation of existing models, and demonstrate that it allows studying how the masses of the legs generate a flexing force that helps the natural bending of the trunk during gallop. We apply our model to six animals, that adopt two different galloping patterns (called transverse and rotatory), and compare their energy efficiency.

Running Dynamics of Rail Vehicles

The importance of simulation calculations in developing railway vehicles and their subsystems is consistently growing compared to physical experiments and track tests [...]

Exploring Patterns of Train Delay Evolution and Timetable Robustness

Uncertainty affects the overall performance of railway systems. It can be captured tracking the successive departure and arrival events of trains at stations in the scheduled railways. Markov chains has shown to be an effective means to model variabilities in the departure and arrival delays of trains. The empirical data of actual operations are used to develop the Markov matrices. Transitions between delay states comprise the internal dynamics of running and dwelling processes in probabilistic terms, presenting particular patterns of deterioration, recovery and state keeping in the prevailing timetable setting. All these features conform to the practice of railway operations as well as train dispatchers and drivers. Hence, delay-based Markov chains becomes a simple and effective tool to predict delays in the following events of trains and distribution of delays over a longer period of time using simple performance measures. We have developed the homogeneous and non-homogeneous Markov models and tested their performances using the actual data collected in the Netherlands railway network. The analysis and evaluation show that the railway corridor considered in this study performs well and the corresponding Markov chain models can be used effectively to predict train delays and to evaluate timetable robustness. The outcomes of the homogeneous and non-homogeneous model are evaluated with respect to the observed data resulting that the non-homogeneous model performs better than the homogeneous model.

A Comparison of a Novel Stretchable Smart Patch for Measuring Runner's Step Rates with Existing Measuring Technologies.

A novel wearable smart patch can monitor various aspects of physical activity, including the dynamics of running, but like any new device developed for such applications, it must first be tested for validity. Here, we compare the step rate while running in place as measured by this smart patch to the corresponding values obtained utilizing ‘‘gold standard’’ MEMS accelerometers in combination with bilateral force plates equipped with HBM load cells, as well as the values provided by a three-dimensional motion capture system and the Garmin Dynamics Running Pod. The 15 healthy, physically active volunteers (age = 23 ± 3 years; body mass = 74 ± 17 kg, height = 176 ± 10 cm) completed three consecutive 20-s bouts of running in place, starting at low, followed by medium, and finally at high intensity, all self-chosen. Our major findings are that the rates of running in place provided by all four systems were valid, with the notable exception of the fast step rate as measured by the Garmin Running Pod. The lowest mean bias and LoA for these measurements at all rates were associated consistently with the smart patch.

Deep-Learning-Based Accurate Identification of Warehouse Goods for Robot Picking Operations

In order to explore the application of robots in intelligent supply-chain and digital logistics, and to achieve efficient operation, energy conservation, and emission reduction in the field of warehousing and sorting, we conducted research in the field of unmanned sorting and automated warehousing. Under the guidance of the theory of sustainable development, the ESG (Environmental Social Governance) goals in the social aspect are realized through digital technology in the storage field. In the picking process of warehousing, efficient and accurate cargo identification is the premise to ensure the accuracy and timeliness of intelligent robot operation. According to the driving and grasping methods of different robot arms, the image recognition model of arbitrarily shaped objects is established by using a convolution neural network (CNN) on the basis of simulating a human hand grasping objects. The model updates the loss function value and global step size by exponential decay and moving average, realizes the identification and classification of goods, and obtains the running dynamics of the program in real time by using visual tools. In addition, combined with the different characteristics of the data set, such as shape, size, surface material, brittleness, weight, among others, different intelligent grab solutions are selected for different types of goods to realize the automatic picking of goods of any shape in the picking list. Through the application of intelligent item grabbing in the storage field, it lays a foundation for the construction of an intelligent supply-chain system, and provides a new research perspective for cooperative robots (COBOT) in the field of logistics warehousing.

Fore-Aft Asymmetry Improves the Stability of Trotting in the Transverse Plane: A Modeling Study.

Quadrupedal mammals have fore-aft asymmetry in their body structure, which affects their walking and running dynamics. However, the effects of asymmetry, particularly in the transverse plane, remain largely unclear. In this study, we examined the effects of fore-aft asymmetry on quadrupedal trotting in the transverse plane from a dynamic viewpoint using a simple model, which consists of two rigid bodies connected by a torsional joint with a torsional spring and four spring legs. Specifically, we introduced fore-aft asymmetry into the model by changing the physical parameters between the fore and hind parts of the model based on dogs, which have a short neck, and horses, which have a long neck. We numerically searched the periodic solutions for trotting and investigated the obtained solutions and their stability. We found that three types of periodic solutions with different foot patterns appeared that depended on the asymmetry. Additionally, the asymmetry improved gait stability. Our findings improve our understanding of gait dynamics in quadrupeds with fore-aft asymmetry.

The Effects of Wobbling Mass Components on Joint Dynamics During Running.

Soft tissue moves relative to the underlying bone during locomotion. Research has shown that soft tissue motion has an effect on aspects of the dynamics of running; however, little is known about the effects of soft tissue motion on the joint kinetics. In the present study, for a single subject, soft tissue motion was modeled using wobbling components in an inverse dynamics analysis to access the effects of the soft tissue on joint kinetics at the knee and hip. The added wobbling components had little effect on the knee joint kinetics, but large effects on the hip joint kinetics. In particular, the hip joint power and net negative and net positive mechanical work at the hip was greatly underestimated when calculated with the model without wobbling components compared with that of the model with wobbling components. For example, for low-frequency wobbling conditions, the magnitude of the peak hip joint moments were 50% greater when computed accounting the wobbling masses compared with a rigid body model, while for high-frequency wobbling conditions, the peaks were within 15%. The present study suggests that soft tissue motion should not be ignored during inverse dynamics analyses of running.

Center of Mass Offset Enhances the Selection of Transverse Gallop in High-Speed Running by Horses: A Modeling Study.

Horses use the transverse gallop in high-speed running. However, different animals use different gaits, and the gait preference of horses remains largely unclear. Horses have fore-aft asymmetry in their body structure and their center of mass (CoM) is anteriorly located far from the center of the body. Since such a CoM offset affects the running dynamics, we hypothesize that the CoM offset of horses is important in gait selection. In order to verify our hypothesis and clarify the gait selection mechanisms by horses from a dynamic viewpoint, we developed a simple model with CoM offset and investigated its effects on running. Specifically, we numerically obtained periodic solutions and classified these solutions into six types of gaits, including the transverse gallop, based on the footfall pattern. Our results show that the transverse gallop is optimal when the CoM offset is located at the position estimated in horses. Our findings provide useful insight into the gait selection mechanisms in high-speed running of horses.

Gearless Track-Friendly Metro with Guided Independently Rotating Wheels

Track–vehicle severe interaction on track with small curve radius results in rail wear and corrugation, and wheel polygonization, which drain considerable resources for rail grinding and wheels re-profiling in metro lines. To reduce the damage caused by track-vehicle severe interaction, the paper analyzes the reasons leading to rail wear and then proposes an architecture of a metro vehicle with independently rotating wheels driven directly by permanent magnet synchronous motors. The architecture is axle guidance, offered by passive linkages, which ensures that all axles are oriented radially, while control strategy was kept as simple as possible, identifying only two basic traction conditions. The concept is first discussed and then validated through a comprehensive set of running dynamics simulation performed with a multibody software to evaluate rail wear and rolling contact fatigue in traction/braking, coasting with different cant deficiency/excess conditions. The multibody dynamics simulation shows that the proposed architecture is virtually capable of avoiding both wear and rolling contact fatigue damages, and achieves the highest possible track friendliness. The concept of the proposed architecture is a track-fiendly metro architecture and could be a good reference for reducing rail-track interaction damages and maintainace cost.

Classification Model for Discriminating Trunk Fatigue During Running.

Fatigue is often associated with increased injury risk. Many studies have focused on fatigue in the lower extremity muscles brought on by running, yet few have examined the relationship between fatigue of the core musculature and associated changes in running gait. To investigate the relationship between trunk fatigue and running dynamics, this study had two goals: (1) to use machine learning to determine which gait parameters are most associated with trunk fatigue; and (2) to develop a machine learning algorithm that uses those parameters to classify individuals with trunk fatigue. We hypothesized that we could effectively differentiate between the non-fatigued and fatigued states using machine learning models derived from running gait parameters. Seventy-two individuals performed a trunk fatigue protocol. Lower extremity running biomechanics were collected pre- and post- the trunk fatigue protocol using an instrumented treadmill and 10-camera motion capture system.The fatiguing protocol involved executing a series of trunk fatiguing exercises until established fatigue criteria were reached. Gait variables extracted from the non-fatigued and fatigued states served as model inputs to aid in the development of the machine learning model that would distinguish between non-fatigued and fatigued running. The machine learning protocol determined three variables - stance time, maximum propulsive GRF and maximum braking GRF - to be the best discriminators between non-fatigued and fatigued running. The SVM with Bagging was the best performing model that discriminated between non-fatigued and fatigued running with an accuracy of 82%, precision of 77%, recall of 90%, and area under the receiver operating curve of 0.91. The machine learning model was effective in classifying between non-fatigued and fatigued running using three gait parameters extracted from GRF waveforms. The ability to classify fatigue using these easy to measure GRF derived parameters enhances the ability for the model to be integrated into wearable technology and the clinical setting to aid in the detection of fatigue and potentially injury, as fatigue is often a precursor to injury.Clinical Relevance- This model has the potential to be implemented in a clinical setting to determine the onset of trunk fatigue through basic gait analysis, involving only the ground reaction forces. This model would be aimed toward injury prevention since fatigue is linked to increased risk of injury.

Capsule Vehicle Dynamics Based on Levitation Coil Design Using Equivalent Model of a Sidewall Electrodynamic Suspension System

A levitation system based on sidewall electrodynamic suspension (EDS) is considered for a capsule vehicle, which is a next-generation high-speed transportation system currently being studied. This levitation system does not require controlling of the gap between the guideway and the vehicle on which the superconducting electromagnet is mounted. However, when the vehicle is operated in a levitated state, the ride comfort is worse than that of the levitation system based on electromagnetic suspension (EMS), making it necessary to develop methods that can ensure good riding comfort. In addition, because the EDS system is complex and nonlinear with a combination of electromagnetics and mechanical dynamics, it is complicated to analyze the dynamic characteristics of the capsule vehicle, and the corresponding numerical analysis is time-consuming. Therefore, to easily understand the running dynamics of a capsule vehicle in the sidewall EMS system, the magnetic suspension characteristics corresponding to the primary suspension are simply modeled by considering the levitation stiffness in the vertical direction and the guidance stiffness in the lateral direction, similar to that in the case of the mechanical suspension. In this study, mathematical models of the levitation and guidance stiffnesses with respect to the speed and position of a vehicle body running at high speeds in a levitated state in the sidewall EDS system were derived for three design proposals of the levitation coil. The dynamic behavior of the vehicle based on the three design proposals was investigated by simulating a capsule vehicle model with 15 degrees of freedom.