Dynamometric Platform Research Articles

On-Screen Visual Feedback Effect on Static Balance Assessment with Perturbations.

In this study, the novel mobile dynamometric platform, OREKA, was utilized to perform an extensive analysis of the centre of pressure behaviour during different tilt motion exercises. This platform is based on a parallel manipulator mechanism and can perform rotations around both horizontal axes and a vertical translation. A group of participants took part in an experimental campaign involving the completion of a set of exercises. The aim was to evaluate the platform's potential practical application and investigate the impact of visual on-screen feedback on centre of pressure motion through multiple balance indicators. The use of the OREKA platform enables the study of the impact on a user's balance control behaviour under different rotational perturbations, depending on the availability of real-time visual feedback on a screen. Furthermore, it presented data identifying postural control variations among clinically healthy individuals. These findings are fundamental to comprehending the dynamics of body balance. Further investigation is needed to explore these initial findings and fully unlock the potential of the OREKA platform for balance assessment methodologies.

Tool-integrated thin-film sensor systems for measurement of cutting forces and temperatures during machining

Effective in-process control mechanisms are vital for the future development of production processes and ask for reliable monitoring of process variables. For this, new tool-integrated sensor systems for measuring cutting forces and temperature for machining of hardened steel are proposed. Thin-film technology is used to apply a thermoresistive temperature sensor in the chip-workpiece contact area for the first time on industrial cutting inserts with chip breaker geometry. Complementary piezoresistive thin-film sensors based on diamond-like carbon (DLC) and manganin layers were developed and deposited on a washer. It was placed beneath the indexable insert to measure the cutting forces. Turning experiments were conducted to study sensor life and accuracy. All sensors showed an adequate lifetime for laboratory purposes. Temperature compensation methods were investigated for force measurement and results compared to forces recorded by a dynamometric platform. While temperature compensation for the DLC-based sensor needs further optimization, results of the manganin-based sensor compared well with the expected cutting forces. The manganin thin-film sensor exhibited rapid responsiveness and great reproducibility, underscoring its prospective utility for real-time monitoring of cutting forces in machining operations.

Texting on a Smartphone While Walking Affects Gait Parameters

Cell phone use while walking is an ever-increasing traffic hazard, and leads to an augmented risk of accidents. There is a rising number of injuries to pedestrians using a cell phone. Texting on a cell phone while walking is an emerging problem among people of different ages. The aim of this experiment was to investigate whether using a cell phone while walking affects walking velocity, as well as cadence, stride width, and length in young people. Forty-two subjects (20 males, 22 females; mean age: 20.74 ± 1.34 years; mean height: 173.21 ± 8.07 cm; mean weight: 69.05 ± 14.07 kg) participated in the study. The subjects were asked to walk on an FDM-1.5 dynamometer platform four times at a constant comfortable velocity and a fast velocity of their choice. They were asked to continuously type one sentence on a cell phone while walking at the same velocity. The results showed that texting while walking led to a significant reduction in velocity compared to walking without the phone. Width, cadence, and length of right and left single steps were statistically significantly influenced by this task. In conclusion, such changes in gait parameters may result in an increased risk of pedestrian crossing accidents and tripping while walking. Phone use is an activity that should be avoided while walking.

Wearable Magnetic Flexonic Sensor Nodes for Simultaneous Normal Force and Displacement Measurements

Illustrated in the context of home-based stroke rehabilitation, this paper presents the design and development of magnetic flexonic sensor nodes (FSNs) with configurable parameters for simultaneous sensing of normal forces and displacement. The FSN is composed of a magnetic sensor in flexible elements that can be embedded in wearable devices and rapid-prototyped at a low cost to facilitate distributed force sensing applications. As an illustration, a shoe insole with 19 embedded FSN for monitoring the plantar force distribution and arch height has been designed, prototyped, and experimentally evaluated by comparing it with a commercial dynamometric platform. The FSN-embedded insole directly measures the arch height and captures the transients of the plantar forces in five different zones in real-time. Because of the simplicity and low cost, FSNs have the potential to facilitate fabricating low-cost sensing systems, for example, for home-based stroke rehabilitation where the insole stiffness and arch height of the embeddable electronic sensors can be configured according to the patient's specific abnormal plantar distribution to adapt to different range and distribution and wearable configuration during different rehabilitation state.

The assessment of lower extremity peripheral artery disease impact on body mass center disorders

BackgroundLower extremity peripheral artery disease is a problem of contemporary medicine and along with the ischemic heart disease it is considered to be a civilization disease. The risk of the disease increases significantly within a group of people reaching the age of 55 years and is closely related to co-occurring hazardous factors, such as diabetes, hyperlipidemia, hypertension or tobacco smoking. The first symptom reported by patients is intermittent claudication. Such symptoms may indicate that lower extremity peripheral artery disease does have an impact on posture disorders and motor skills. MethodsThe study covered four stages. The first stage involved medical interviews to obtain information regarding anthropometry, age, motor organ surgery, concomitant diseases and the lifestyle. In the following stage the value of the ankle brachial index for both lower limbs were calculated. In case of symptomatic patients, additionally, the location of artery stenosis/aortoiliac section, was verified. The third stage involved using a dynamometric platform for determination of the body mass center position for both studied groups. In the fourth stage a treadmill walk test was used to assess the participants for intermittent claudication. FindingsBased on the obtained results, an attempt was taken to observe the relationship between the clinical characteristics of the disease and the body mass center position deviations. Interpretation: The attempt was undertaken to assess whether the measurement of body mass center position might be a diagnostic parameter to evaluate the patient's condition and thus an indication for taking a decision for surgical treatment or rehabilitation.

Compensated and decompensated vertical posture of a patient with scoliosis

In 40 patients with thoracic and combined scoliosis of III and IV degrees, the loading of both legs during standing and walking was determined using Kistler dynamometric platforms. The results of the studies and analysis of posture characteristics allowed the authors to distinguish two options for compensating for the imbalance in the body that occurs during the formation of the primary curvature of the spine. A number of provisions are made regarding the pathogenesis of scoliosis, predicting the course of the disease, as well as treatment

Influence of insole material density in the stability of patients with prosthetic unilateral transtibial amputation

People with lower limb amputation present greater displacements of their centre of gravity in a static situation than able-bodied individuals, as they depend on visual information to a greater extent, which implies an altered stability pattern. The efficacy of different hardness of plantar support to help maintain stability has not yet been determined. The aim of the present study is to assess stability in people with unilateral transtibial amputation with prosthesis in a static situation with insoles of different degrees of hardness and visual conditions with respect to the able-bodied population. For this purpose, 25 patients with amputation and 25 able-bodied individuals were included in both groups, postural stability was assessed by stabilometry. This assessment was carried out under normal conditions (on the floor of the dynamometric platform with eyes open), and under altered conditions (with the interposition of different materials such as plantar support: rigid and soft insoles and, eyes shut). Three variables were considered to assess stability: length of movement of the barycenter (mm), lateral velocity (mm/sg) and anterior velocity (mm/sg). All of them were analysed with the patient in static on the dynamometric platform. The results showed statistically significant differences between the two groups, (amputees and controls) with less stability in the amputee group (p < 0.05) when analysing the variables of length of movement of the barycenter, lateral velocity and anterior velocity. Amputee patients with open eyes exhibited greater stability than those with closed eyes. The hard insoles improved the stability data in amputees (length of movement of the barycenter and anterior velocity) with respect to the barefoot condition, and the soft insoles showed less stability than the patients with hard insoles, or than the barefoot patients. From the results obtained in this study, we can conclude that the PP-DWST 4 mm rigid insoles improve static stability in people with amputation. However, soft insoles impair stability and are therefore discouraged.

Kinetic analysis of gait in adults with asymptomatic flatfoot

Purpose: The aim of our study was to assess the influence of asymptomatic flatfoot on the kinetic parameters of the lower limb during gait. Methods: Individuals of both sexes were studied: 15 women [age 25 ± 5 years] and 19 men [age 25 ± 4 years] with bilateral asymptomatic flatfoot, as well as 16 women [age 26±4 years] and 14 men [age 24 ± 3 years] with normal feet on both sides. A threedimensional VICON motion analysis system coupled with KISTLER dynamometric platforms was used to perform kinetic gait analysis. Results: Women with flatfoot showed significantly lower maximal relative moments in the ankle in the sagittal plane (p &lt; 0.05) and significantly lower maximal relative moments in the knee in the sagittal plane in the Terminal Stance (p &lt; 0.001). In men, a significant difference was found in terms of hip rotation moment in the transverse plane in the Mid Stance (p &lt; 0.01): men with normal feet showed moments of external rotation, while men with flatfoot generated internal rotational moments. Moreover, men with flatfoot showed significantly lower (p &lt; 0.01) maximal relative moments in the knee in the transverse plane in the Mid Stance. Conclusions: Women with flatfoot have a weakened lower limb propulsion mechanism, whereas, in men with flatfoot, there is a change in the mechanics of the lower limb in the transverse plane. Our findings cast some doubt on flatfoot as a putative risk factor for stress injuries and degenerative changes in lower-limb structures, and suggest that gender differentiation should be taken into account in the analysis and therapy of flatfoot.

BIOMECHANICAL CHARACTERISTICS OF THE LOCOMOTOR ACTIVITY IN CHILDREN OF 3–6 YEARS OLD WITHOUT MOVEMENT DISORDERS

Purpose of the study — to form normative guidelines for the values of kinetic and kinematic parameters of gait in children aged 3–6 years without motor disorders. Materials and methods. Using video analysis to determine the normative range of the values of locomotor characteristics, the gait profile (Gait profile Score — GPS) was assessed in children aged 3–6 years (n=16) without movement disorders in the laboratory of biomechanics of the Ilizarov Centre. Kinematic parameters were recorded with Qualisys 7+ optical cameras (n=8), kinetic parameters were recorded using Kistler dynamometric platforms (n=6). The examination consisted of two tests: 1 — independent walking with the usual speed of movement on a 7-m track; 2 — carried out on the background of comfortable for the child accompaniment by an adult for 1 hand. Analysis of results was carried out by automated calculations of kinematics and kinetics values using descriptive statistics. The assessment of the normality of the distribution of the studied parameters was performed according to 12 univariate criteria. Results. It has been established that the main characteristics of locomotor activity in age-homogeneous groups of children aged 3–6 years obey the normal distribution function and, therefore, the normative range of functioning values can be determined by the rule of sigma deviations. The article presents selective values of kinematic and kinetic parameters of gait in children aged 3–6 years without movement disorders recommended as normative guidelines. Conclusions. For children 3–4 years old, examination conditions are acceptable both independently and with support by the hand. For children aged 5–6 years, the examination should include only independent walking, walking with support by the hand distorts the structure of the locomotor stereotype of the accompanying person, and therefore such a gait should be regarded as unnatural

Development of a Fast Thermal Model for Calculating the Temperature of the Interior PMSM

A 40 kW–4000 rpm interior permanent magnet synchronous machine (IPMSM) applied to an electric vehicle (EV) is introduced as the study object in this paper. The main work of this paper is theoretical derivation and validation of the first-order and multi-order transient lumped-parameter thermal network (LPTN) for the development of a fast thermal model. Based on the first-order LPTN built, the study finds that the heat transfer coefficient of fluid and thickness of the air gap layer are the main influencing factors for the final temperature and time of reaching the steady state. The larger the heat transfer coefficient of fluid is, the lower the steady node temperature is. The smaller the air layer thickness is, the lower the steady node temperature is. The multi-order LPTN theory is further deduced based on the extension of the first-order LPTN. For the constant load and rectangular periodic load, transient node temperatures of the IPMSM are obtained by modeling and solving the first order inhomogeneous differential equations. Temperature rise curves and efficiency maps of the IPMSM under load conditions are realized on a dynamometer platform. The FLUKE infrared-thermal imager and the thermocouple PTC100 are used to validate the mentioned method. The experiment shows that the LPTN of the IPMSM can accurately predict the node temperature.

Generalized cutting force model for peripheral milling of wood, based on the effect of density, uncut chip cross section, grain orientation and tool helix angle

The influence of the grain angle on the cutting force when milling wood is not yet detailed, apart from particular cases (end-grain, parallel to the grain, or in some rare cases 45°-cut). Thus, setting-up wood machining operations with complex paths still relies mainly on the experience of the operators because of the lack of scientific knowledge easily transferable to the industry. The aim of the present work is to propose an empirical model based on specific cutting coefficients for the assessment of cutting force when peripheral milling of wood based on the following input: uncut chip thickness and width, grain angle (angle between the tool velocity vector and the grain direction of the wood), density and tool helix angle. The specific cutting coefficients were determined by peripheral milling with different depths of cut wood disks issued from different wood species on a dynamometric platform to record the forces. Milling a sample into a round shape (a disk) allows to measure the cutting forces toward every grain angle into a sole basic diameter reduction operation. Force signals are then post-processed to carefully clean the natural vibrations of the system without impacting their magnitudes. The experiment is repeated on five species with a large range of densities, machining two disks per species for five depths of cut in up- and down milling conditions for three different tool helix angles. Finally, a simple cutting force model, based on the previously cited parameters, is proposed, and its robustness analysed.

Vulnerability of the foot's morphological structure to deformities caused by foot loading paradigm in school-aged children: a cross-sectional study

The study aimed to assess the association between the key predictive foot structure variables and its loading paradigm in 625 school-aged children. Clinical appraisal relied primarily on having the plantar parts of their feet comprehensively assessed with Podoscan 2D Foot CAD, and a dynamometer platform, the research tools of choice widely acknowledged for their overall accuracy and reliability, with a view to determining the distribution of respective foot loads, as well as addressing both balance and gait issues. The Clarke's angle, Wejsflog index, length and width of the feet, regardless of gender, proved the key predictive variables for the foot-loading paradigm. Notably the Clarke's angle, construed the most sensitive variable in assessing flat-footedness, offered an extra added value in overall investigative effort. The actual design of the study protocol effectively complements a standard clinical assessment procedure, whereas by comprehensively addressing those variables, it is also believed to aid clinicians in gaining an extra, hands-on, diagnostic potential, so that any teenagers exposed to the highest risk of developing foot deformities could effectively be identified through pertinent screening tests, and consequently offered a task-oriented, therapeutic management, specifically aimed at preventing potential postural complaints in later life.

Comparison of postural control between strabismic and non-strabismic children

Abstract Objective To compare the postural control of children with strabismus versus non-strabismus children. Material and methods Cross-sectional cohort study with a total of 171 children, including 73 children with esotropia, 24 with exotropia, and 74 controls. Postural control was determined using a dynamometric platform in a standing position in various conditions: eyes open and eyes closed, near and gaze fixation, and with and without foam pad. The studied variables were the area, the mean speed, and the lengths in the X and Y axis of the centre of pressure displacement. Results Children with esotropia and exotropia had significantly higher mean values (speed, lengths of X and Y) compared to controls. In the open-eye, far distance fixation, and on foam pad, as well as under exam conditions; with eyes open, without foam pad, and far distance fixation, the exotropia values were higher than those of endotropia and controls. With eyes closed, there were no differences between the three groups under the described examination conditions, but their values were worse compared to their respective ones with eyes open. Conclusions The children with strabismus had a worse postural control than the non-strabismus ones. All of the them appeared to be more unstable with eyes closed than with eyes open, which demonstrates that vision plays an important relevant role in postural stability in both strabismus and non-strabismus children.

The effect of motor control training according to the Kinetic Control concept on the back pain of female football players.

Due to a significant burden associated with training sessions and matches, female football players often suffer from lumbar pain. Physical exercise is considered an effective form of therapy for this condition. The exercises in the Kinetic Control concept are one of the forms of motor control training. The aim of the study was to evaluate the effectiveness of motor control training according to the Kinetic Control concept on the level of lumbar spine pain, degree of disability, functional level and load distribution of lower limbs in football players. The study included 18 football players, randomly divided into two study groups: A - female players implementing their training plan with additional Kinetic Control training (n= 9) and B (control) - female players implementing their training plan only (n= 9). Pain intensity was measured using Visual Analogue Scale (VAS) and Laitinen's questionnaire. Functional disability was assessed using Oswestry Disability Index (ODI) and Back Pain Functional Scale (BPFS). The asymmetry index was assessed in a balance test with open and closed eyes and a countermovement jump (CMJ). There was a significant statistical difference between the groups (p< 0.05) in measurements using VAS, ODI and BPFS, in favor of group A. Asymmetry index values in tests on the dynamometer platform did not differ significantly between the groups (p> 0.05). A statistically significant correlation was found between the asymmetry index score in the closed-eye balance test (r= 0.567, p= 0.049) and the CMJ landing phase (r= 0.641, p= 0.033), and the level of pain measured using VAS. Motor control training in the Kinetic Control concept reduced the pain symptoms of the lumbar spine and the degree of disability and increased the functional level in football female players.

A sitting or standing position – which one exerts more loads on the musculoskeletal system of the lumbar spine? Comparative tests based on the methods of mathematical modelling

The work aimed to assess the functioning of the musculoskeletal system within the lumbar spine in relation to everyday postures of sitting and standing. The comparative analysis was based both on experimental tests and computer simulations performed in the AnyBody Modeling System environment. Input data used to prepare models were based on the information obtained in experimental tests. The test participants were tasked with adopting two postures: 1) standing position and 2) sitting position. Kinematics measurements were performed using the Zebris ultrasonic system. During sitting position, the tests additionally involved the use of a dynamometric platform measuring reaction forces occurring between buttocks and the seat. The comparative analysis included measurements of the trunk inclination angle and the pelvic inclination angle as well as results of computer simulations. The sitting posture is responsible for increased trunk inclination and a change in the position of the pelvis. In terms of the sitting position, it was possible to observe an increase in the loads affecting individual intervertebral joints of the lumbar spine by 155-184% in comparison with the standing posture (100%). Simulations revealed an increased muscle activity of the erector spinae, abdominal internal oblique muscles and abdominal external oblique muscles. Adopting a sitting position increases the loads on the lumbar spine and increases the activity of the erector spinae and abdominal muscles compared to the standing position, which is caused by change in the position of the pelvis and the curvature of the lumbar region.

Effects of Motor Control Training on the Concept of Kinetic Control in Treating Patella Ligament Tendinopathy in a Female Football Player: A Case Study

Objectives: Patellar ligament tendinopathy, also known as jumper’s knee, is a group of pain symptoms of the anterior side of the knee joint. The Kinetic Control (KC) concept uses the movement control rating system, based on motor tests and exercises aimed at re-educating motor control. The present study explored the effects of motor control training on the KC concept in treating patella ligament tendinopathy in a female football player. Methods: The current case study was conducted on a 20-year-old female football player. She had been complaining of pain in the front of the right knee joint for two months. Her treatment involved KC training was conducted for 6 weeks (3 times a week for 30 minutes). To investigate the effectiveness of the presented therapy, the following tools were used: Visual Analogue Scale (VAS), The Victorian Institute of Sport Assessment–Patella (VISA-P scale), the Modified Laitinen Pain Questionnaire, Counter Movement Jump (CMJ) test on a dynamometric platform, and quadriceps muscle isometric test. The Asymmetry Index (AI) was applied to assess the asymmetry of quadriceps strength and lower limb loading. Results: The degree of pain (i.e. measured by the VAS) decreased from 7 points at pre-training to 1 point after 6 weeks of therapy. In the VISA-P measurement, pain decreased as a result of an increase in points from 53 to 82. Pain complaints (i.e. measured using the Laitinen questionnaire) decreased from 7 to 2 points. After treatment, the AI improved in all phases of the tests. Discussion: The achieved data indicated that the neuromuscular KC training was effective in treating patellar tendinopathy. However, it is necessary to conduct further studies with larger sample size.

Dual-tasking effects on static and dynamic postural balance performance: a comparison between endurance and team sport athletes.

In sports, postural balance control has been demonstrated to be one of the limiting factors of performance and a necessary component to achieve any sport technique. Team players (TP) must process and react to multiple external stimuli while executing at the same time the skills of the game. By contrast, endurance athletes (END) must perform the same gesture repetitively without a concurrent coordination of continuous stimuli-related actions. However, END are used to facilitate their physical performance by adopting cognitive strategies while performing their sport gesture. Therefore, we aimed to investigate static and dynamic balance performance in these two types of athletes, both in single and dual-task conditions. Nineteen END and sixteen TP underwent a static and a dynamic balance assessment on a dynamometric platform and an instrumented oscillating board, respectively. Among TP static but not dynamic postural balance performance was negatively affected by dual-tasking considering the area of the confidence ellipse (p < 0.001; d = 0.52) and the sway path mean speed (p < 0.001; d = 0.93). Conversely, END unaltered static balance performance but showed an overall improvement in the dynamic one when dual-tasking occurred. The limited human processing capacity accounted the worsening of the cognitive performance in both TP (p < 0.05; d = 0.22) and END (p < 0.001; d = 0.37). Although TP are more used coping dual tasking, the better performance of END could be accounted for by the employment of the external attentive focus (i.e. counting backward aloud) that called into play a strategy close to those adopted during training and competitions. These surprising results should be considered when driving and developing new trainings for team players in dual-tasking conditions.

Post-Effect on the Centre of Feet Pressure during Stance by Continuous Asymmetric Mediolateral Translations of a Supporting Platform—A Preliminary Study in Healthy Young Adults

Various diseases are associated with the impaired control of the medio-lateral (ML) position of the centre of feet pressure (CoP), and several manoeuvres have been proposed for enhancing the CoP symmetry. Here, we assessed in healthy standing subjects the feasibility and outcome of a novel protocol entailing a reaction to a continuous asymmetric ML displacement (10 cm) of the support base. The periodic perturbation consisted of a fast half-cycle (0.5 Hz) followed by a slow half-cycle (0.18 Hz). One hundred successive horizontal translation cycles were delivered in sequence. Eyes were open or closed. CoP was recorded before, after, and during the stimulation by a dynamometric platform fixed onto the translating platform. We found that the post-stimulation CoP was displaced towards the direction of the fast half-cycles. The displacement lasted several tens of seconds. Vision did not affect the amplitude or duration of the post-stimulation effect. The magnitude of post-stimulation CoP displacement was related to the perturbation-induced ML motion of CoP recorded during the stimulation. Over the successive perturbation cycles, the time-course of this motion revealed an adaptation phenomenon. Vision moderately reduced the adaptation rate. The findings support the feasibility of the administration of a simple asymmetric balance perturbation protocol in clinical settings to help patients recover the symmetry of the CoP. This protocol needs to be further validated in older populations and in patients.

Comparativa del control postural entre niños estrábicos y no estrábicos

ObjectiveTo compare the postural control of children with strabismus versus non-strabismus children. Material and methodsCross-sectional cohort study with a total of 171 children, including 73 children with esotropia, 24 with exotropia, and 74 controls. Postural control was determined using a dynamometric platform in a standing position in various conditions: eyes open and eyes closed, near and gaze fixation, and with and without foam pad. The studied variables were the area, the mean speed, and the lengths in the X and Y axis of the centre of pressure displacement. ResultsChildren with esotropia and exotropia had significantly higher mean values (speed, lengths of X and Y) compared to controls. In the open-eye, far distance fixation, and on foam pad, as well as under exam conditions; with eyes open, without foam pad, and far distance fixation, the exotropia values were higher than those of endotropia and controls. With eyes closed, there were no differences between the 3 groups under the described examination conditions, but their values were worse compared to their respective ones with eyes open. ConclusionsThe children with strabismus had a worse postural control than the non-strabismus ones. All of the them appeared to be more unstable with eyes closed than with eyes open, which demonstrates that vision plays an important relevant role in postural stability in both strabismus and non-strabismus children.

Speed running is determined by strength and power in young football players

Introduction: For years researchers and trainers have been looking for determinants of sports talent in the youngest and also in the relationship between individual motor features relevant in given sport disciplines. There is a fundamental consensus in the opinion that the strength and power of the lower limbs are correlated with the speed of running. However, this relationship also among the youngest is not so clear. The purpose of the work was to show the relationship between strength and power generated during vertical jump and achieved height jump and the speed of flat running in the youngest footballers. Material and methods: The research covered 75 children training football at the age of 6–14 years divided into two age groups. The subjects made a countermovement jump on a dynamometric platform measuring strength, power, speed of rebound and the height obtained, after which they performed a flying run over a distance of 20 m. Results: A strong, positive correlation was demonstrated between all dynamic and kinetic parameters of the jump and running speed. This correlation turned out to be clearly stronger in the older group of football players than in the younger group. Conclusions: The obtained results suggest that strength and power are good predictors, such an important feature in football as the player’s motion speed, already at the basic level of training.