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1

Human-induced force reconstruction using a non-linear electrodynamic shaker applying an iterative neural network algorithm

Peláez-Rodríguez César, Magdaleno Álvaro, Salcedo-Sanz Sancho, Lorenzana Antolín

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

|

Vol. 71, nr 3

art. no. e144615

EN

An iterative neural network framework is proposed in this paper for the human-induced Ground Reaction Forces (GRF) replication with an inertial electrodynamic mass actuator (APS 400). This is a first approach to the systematization of dynamic load tests on structures in a purely objective, repeatable and pedestrian-independent basis. Therefore, an inversion-free offline algorithm based on Machine Learning techniques has been applied for the first time on an electrodynamic shaker, without requiring its inverse model to tackle the inverse problem of successful force reconstruction. The proposed approach aims to obtain the optimal drive signal to minimize the error between the experimental shaker output and the reference force signal, measured with a pair of instrumented insoles (Loadsol©) for human bouncing at different fre- quencies and amplitudes. The optimal performance, stability and convergence of the system are verified through experimental tests, achieving excellent results in both time and frequency domain.

2

Zastosowanie systemu analizy ruchu BTS do określenia chwili utraty stabilności

Matuszewska Agata, Liszkowski Jakub, Walczak Tomasz, Buśkiewicz Jacek

Aktualne Problemy Biomechaniki

|

2019

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z. 17

69--76

PL

W pracy przeprowadzono próbę wyznaczenia chwili utraty stabilności dla upadków z pozycji statycznej. Pozycją początkową, jaką przyjmowała osoba badana, było stanie na dwóch nogach z rękami wzdłuż tułowia. Rejestracji ruchu dokonano dzięki wykorzystaniu systemu BTS. W celu wyznaczenia chwili utraty stabilności zaproponowano i opracowano własne miary i parametry, bazujące na pomiarach wykonanych z użyciem platform dynamometrycznych oraz systemu analizy ruchu. Dla analizowanego przypadku ruchu wielkości te pozwoliły na szacunkowe wyznaczenie chwili utraty stabilności.

EN

Assessing of human stability loss was performed at this work in case of falls from a static position. At the beginning patient takes the starting position as standing on two legs with hands along the thorax. Human motion registration was performed by using BTS system. In order to determine the instant of human stability loss the new measures and parameters were proposed, which based on measurements from force platforms and motion analysis system. These parameters allowed to assess the instant of stability loss for analyzed motion.

3

The influence of minimalist and conventional sports shoes and lower limbs dominance on running gait

Jandova S., Volf P., Vaverka F.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 3

3--9

EN

Purpose: The aim of this study was to determine how minimalist running shoes (MRS), conventional running shoes (CRS) and the dominance of lower limbs influence the running gait. Methods: Trained recreational runners (N = 13) who have been engaged in regulary running for more than one year were participants in this study. They were experienced with using MRS and CRS for more than half year and they used both types of shoes. An in-shoe pressure measuring system (Pedar-X®, Novel, Munich, Germany) was used to monitor plantar pressure and vertical force and the temporal parameters when running in MRS and CRS during the stance phase, the swing phase and over one stride. Results: Running in CRS significantly prolonged stance, swing and stride phases by 2–11% compared to MRS. In contrast, when running in MRS significantly larger values of maximum pressure (9–14%) and maximum vertical force (3–7%) than in CRS were found. Conclusions: For this reason, running in MRS could be recommended to recreational runners only with care. The effect of limb dominance on temporal characteristics was detected when running in CRS. Significantly longer stance phase for dominant limb is associated with a shorter swing. The kinematics variables were significantly higher for dominant limb than for non-dominat limb when running in MRS and CRS (by 12–23%).

4

Reference values of spatiotemporal parameters, joint angles, ground reaction forces, and plantar pressure distribution during normal gait in young women

Fryzowicz A., Murawa M., Kabaciński J., Rzepnicka A., Dworak L. B.

Acta of Bioengineering and Biomechanics

|

2018

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Vol. 20, no. 1

49--57

EN

The aim of this study was to establish the reference values of spatiotemporal parameters, joint angles, ground reaction forces and plantar pressure distribution collected simultaneously on the same measurement path during normal gait in a homogenous group of young, healthy women. Methods: The studied group consisted of 28 healthy women aged 21 years on average. The motion capture system BTS Smart-D, 2 AMTI force platforms and Footscan pedobarographic platform were used in this research. The 14-metre measurement path and the 6-metre distance that examined women had to walk through before entering the measurement area ensured that a natural gait pattern was recorded. Statistical analysis was performed to evaluate differences between right and left lower extremities. Results: The applied method enabled collecting several parameters regarding normal female gait biomechanics such as: spatiotemporal parameters, angle-time characteristics as well as range of motion of pelvis, hip, knee and ankle joints in gait cycle, force-time characteristics and peaks of ground reaction force components in stance phase, peak pressure and time of loading of defined foot regions in stance phase. Conclusions: The results may be used by clinicians, physiotherapists or researchers as a reference in diagnosing gait disorders or evaluating patient’s walking pattern. In recent literature there are some disparities in gait parameters reference values even regarding similar research groups. These differences may arise from distinct method, slower or faster gait, other laboratory environment etc. This should be considered and more than one source of normative values should be checked when searching for reference data.

5

Shoe insert embedded foot pressure monitoring system

Marciniak B., Lutowski Z., Bujnowski S., Marciniak T.

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2017

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no. 3

91--95

EN

The article presents the technical solution of the shoe insert, which can measure the foot pressure on the ground, and the proposal of an algorithm, which based on the received data of a shoe insert, decides whether the investigated person walks or runs. The algorithm is characterized by low computational complexity, which allows it to be used in mobile devices.

PL

W artykule przedstawiono propozycję rozwiązania technicznego wkładki do obuwia służącej do pomiaru nacisku stopy na podłoże oraz propozycję algorytmu, który na podstawie otrzymanych danych z czujników tensometrycznych wkładki podejmuje decyzję, czy badana osoba idzie czy biegnie. Algorytm charakteryzuje się małą złożonością obliczeniową, co pozwala na jego zastosowanie w urządzeniach mobilnych.

6

Modelowanie obciążeń dynamicznych w formie przysiadów na kładkach dla pieszych

Pańtak M.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2017

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z. 64, nr 3/I

189--202

PL

Konstrukcje budowlane charakteryzujące się zwiększoną podatnością dynamiczną i możliwością występowania drgań odczuwalnych przez ich użytkowników narażane są często na intencjonalne wzbudzanie drgań przez osoby wykonujące podskoki lub przysiady. Obciążenia dynamiczne tego typu wystąpić mogą m.in. na: kładkach dla pieszych, trybunach stadionowych, stropach budynków (podczas wydarzeń sportowo-rekreacyjnych, dyskotek, koncertów). W referacie przedstawiono charakterystykę obciążeń dynamicznych w formie sił reakcji podłoża generowanych podczas ciągłych, rytmicznych przysiadów wykonywanych przez jedną osobę wraz z propozycją modeli matematycznych tych obciążeń. Zaproponowane modele opracowano w oparciu o wyniki badań laboratoryjnych sił reakcji podłoża i wstępnie zweryfikowano w drodze dynamicznych analiz numerycznych oraz badań terenowych przykładowych kładek dla pieszych. Wyniki analiz i badań potwierdziły poprawność i skuteczność stosowania modeli w celu wyznaczania wartości sił reakcji podłoża powstających podczas ciągłych, rytmicznych przysiadów oraz ustalania wartości odpowiedzi dynamicznej konstrukcji.

EN

Dynamic forces generated by moving persons can lead to excessive vibration of the long span, slender and light-weight structure such as floors, stairs, stadium stands and footbridges. These dynamic forces are generated during walking, running, jumping and rhythmical body swaying in vertical or horizontal direction etc. One of the important type of dynamic loading of a susceptible and light-weight structures can be the ground reaction forces generated during rhythmically repeated squats. In the paper the load models of the ground reaction forces generated during partial squats have been presented. Elaborated models was compared to the forces measured during laboratory tests carried out by author in wide range of frequency using force platform. Moreover, the load models were initially validated during dynamic numerical analyses and dynamic field tests of the exemplary footbridges.

7

Foot mechanics in young women are altered after walking in high-heeled shoes

Winiarski S., Rutkowska-Kucharska A., Zostawa P., Uścinowicz-Zostawa N., Klich S.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 3

107--113

EN

Nowadays, fashion has caused that many young women are wearing high-heeled shoes. Therefore, the aim of this study was to examine the effects of long-term walking in high-heeled shoes on the foot mechanics during barefoot gait. Methods: Forty-three young women (22 ± 2.1 years) divided into two groups participated in this retrospective cohort study. The first group was composed of women who frequently wear high-heeled footwear. The second, infrequent wearers group, consisted of women who preferred flat-heeled shoes. Measurements of gait parameters were recorded for barefoot gait. A motion analysis system and two force plates were used in order to evaluate the lower-limb rocker mechanism, transverse foot arch height and parameters of ground reaction force. Results: Walking in high-heeled shoes modified barefoot foot mechanics, which manifested itself in a shorter duration (by ca. 4%) of the first and second rocker and a significantly longer duration (by 5%) of the third rocker phase as well as a substantial reduction in height of the transverse foot arch (by around 50%) in women habitually walking in high-heeled shoes. A significantly shorter relative duration of the third rocker (44.3% of cycle time) and greater value of the vertical component of ground reaction force (114.7% BW) in the third rocker phase were found in the group of women habitually walking in high-heeled shoes. Conclusions: The mechanism of foot rolling, with flattened foot arch, and significantly higher values of the vertical component of ground reaction force and shorter time might lead to overload in lowerlimb joints in young women.

8

Dynamic load indicators for take-off–landing sequence in blocks and attacks of elite female volleyball players

Kabaciński J., Dworak L. B., Murawa M., Rzepnicka A.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 1

41--46

EN

Purpose: Dynamic loads during landings determined by the ground reaction forces (GRFs) may elaborate internal loads and increase the risk of overload knee injuries as a result of performing volleyball jumps many times. The study dealt with a biomechanical assessment of dynamic load indicators in female volleyball players for the motion sequence of take-off–landing in blocks and attacks. Methods: Twelve professional female volleyball players participated in the study. Blocks and attacks were filmed by two cameras. GRFs vs. time graphs were recorded with the use of a force platform. Values of dynamic load indicators in terms of the relations of peak of vertical component of GRF, build-up index of this force (BIF), and power output (P) during landing to the vGRF, BIF and P during take-off (L/T) were calculated. Results: The statistically significant ( p < 0.05) highest values of L/T indicators were found for back row attack spikes: 2.4 (vGRF), 12.2 (BIF) and 3.1 (P). In the case of blocks, slide attack spikes and attack line spikes, results of these variables were in range: 1.8÷2.1, 5.9÷7.6 and 2.1÷2.9, respectively. Conclusions: The reduction of GRFs during landings contributes to decreasing the level of the load indicators L/T which should minimize the incidence of anterior cruciate ligament and patellar tendon injuries in female volleyball players.

9

Comparison of ground reaction forces during the Basic Step on the Core Board platform at various levels of stability

Karczewska M., Madej A., Sadowska A., Mastalerz A., Urbanik Cz.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 4

63--70

EN

Purpose: The aim of this paper was to examine and compare the changes of ground reaction forces observed during the Basic Step on the Core Board fitness device at various levels of stability. Material and method: The study involved 10 female students. Participants stepped on and off the Core Board 10 times at 3 levels of stability. After completing a series of steps, the Core Board’s stability was modified and the participant repeated the whole series. The measurement platform to examine three components of the reaction force (horizontal in the sagittal and frontal planes, and vertical) was used. Results: The ground reaction force (GRF) observed on the Core Board, in the vertical and horizontal components is higher at all three levels of stability than on the platform without the device. Significant differences in GRF were observed in the horizontal component in the frontal plane (Fz) at all three levels of mobility as well as in impulse, measured on platforms with the device. Conclusion: The results on the Core Board training device present highest horizontal ground reaction forces in frontal plane at the highest level of Core Board mobility and this showing little medio-lateral stability and a more reactive way of movement regulation of the participants. As a consequence of the force patterns found it may be suggested that fitness training concepts should focus more possibly higher strains on the locomotor system most likely caused by changed ground reaction force patterns, an idea that has to be further analyzed with more complex measurement approaches.

10

Differences in pediatric vertical ground reaction force between planovalgus and neutrally aligned feet

Pauk J, Szymul J.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 2

95--101

EN

Ground reaction forces (GRF) reflect the force history of human body contact with the ground. The purpose of this study was to explore human gait abnormalities due to planovalgus by comparing vertical GRF data between individuals with planovalgus and those with neutrally aligned feet. Second we estimated associations between various measurements and vertical GRF parameters in a pediatric population. Boys and girls between the ages of 4 and 18 years (72 planovalgus feet and 74 neutrally aligned feet) took part in this study. Ground reaction forces were recorded by two Kistler platforms and normalized to body weight. Comparison of vertical GRF between planovalgus and neutrally aligned feet suggests that the first and the second peaks of vertical force (Fz1, Fz2) are most affected by planovalgus. The results also indicate that neutrally aligned feet display a different ground reaction force pattern than planovalgus, and that differences between boys and girls may be observed. The shape of the vertical GRF curve can help in clinical interpretation of abnormal gait.

11

Examination of the effect of psychophysical factors on the quality of human gait recognition

Derlatka M.

Acta Mechanica et Automatica

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2014

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Vol. 8, no. 4

194--198

EN

The paper presents an analysis concerning the influence of selected psychophysical parameters on the quality of human gait recognition. The following factors have been taken into account: body height (BH), body weight (BW), the emotional condition of the respondent, the physical condition of the respondent, previous injuries or dysfunctions of the locomotive system. The study was based on data measuring the ground reaction forces (GRF) among 179 participants (3 315 gait cycles). Based on the classification, some kind of confusion matrix were established. On the basis of the data included in the matrix, it was concluded that the wrong classification was most affected by the similar weight of two confused people. It was also noted, that people of the same gender and similar BH were confused most often. On the other hand, previous body injuries and dysfunctions of the motor system were the factors facilitating the recognition of people. The results obtained will allow for the design of more accurate biometric systems in the future.

12

Integral method (IM) as a quantitative and objective method to supplement the GMFCS classification of gait in children with cerebral palsy (CP)

Dziuba A., Bober T., Kobel-Buys K., Stempień M.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 2

105--111

EN

Gait analysis is an objective tool for the clinical assessment of locomotor activity in children with cerebral palsy (CP). Correct diagnosis and properly planned rehabilitation are necessary for enhanced motor functions in persons suffering from cerebral palsy. Orthoses, orthopedic operations, medications and physiotherapy are the most common treatments. However, there is still a lack of objective methods for assessing motor behavior and monitoring the progress of recovery. The aim of the study was to use the ground reaction force patterns generated during walking to create the Integral Method (IM), which could become an objective tool that could supplement the functional classification of CP children based on the Gross Motor Function Classification System (GMFCS). A total of 15 healthy children and 34 children with CP who walk independently participated in the study. A Kistler force plate and GRFintegral software were used. Of the 34 measurements based on the IM for CP children, 17 matched the level assigned by the GMFCS, 2 children were assigned a higher level, and 15 were assigned a lower level. Pearson’s correlation coefficient between the IM and the GMFCS was moderate (r = 0.61, p ≤ 0.01). Asymmetry was found in 11 cases. The IM supplements the GMFCS and is an objective and quantitative assessment of motor abilities. The method allows for the detection of asymmetry, diagnosis of the improvement of gait pattern and assessment of foot support technique. With the appropriate software, the IM provides pediatricians, neurologists, orthopedists, surgeons and physiotherapists with a simple and fast way to assess gait.

13

Próba stworzenia kryteriów oceny funkcji chodu z wykorzystaniem platformy PDM-S

Jaszczur I., Koprowski P., Wrzosek Z.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2013

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Vol. 19, nr 1

24--31

PL

Chód, jako podstawowa forma lokomocji, jest przedmiotem zainteresowań i wielu opracowań, począwszy od patologii chodu po sport wyczynowy. Badaniu podlegają różne aspekty chodu, takie jak np.: długość i częstotliwość kroków, analiza fazy podparcia i wymachu, przebieg sił reakcji podłoża, charakterystyka kinematyki stawów. Szczegółowymi zagadnieniami analizy chodu są: kinematyka, kinetyka, dynamiczna elektromiografia oraz ocena kosztów energetycznych. W niniejszej pracy zaprezentowana została próba stworzenia kryteriów oceny funkcji chodu za pomocą platformy dynamograficznej PDM-S, z uwzględnieniem wpływu masy ciała. Utworzony wzorzec, w dalszym etapie, może posłużyć do badań nad wpływem treningu lub nad ubytkami sprawności, wynikającymi z przyczyn patologicznych.

EN

Many researchers are interested in gait as the primary form of transportation. Various aspects of gait can be analyzed as e.g. length and frequency of steps, support and swing phase, the course of ground reaction forces, joint kinematics. Specific issues relating to gait are among others: kinematics, kinetics, dynamic electromyography and assessment of energy costs. In this paper, an attempt to create criteria for the assessment of gait function by means of the PDM-S platform, with influence of body weight, will be presented. The obtained pattern can be used for further examination on the effects of training or pathological changes of locomotory system.

14

Analiza obciążeń w step aerobics na podstawie literatury

Błażkiewicz M., Kowalczyk P.

Aktualne Problemy Biomechaniki

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2008

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z. 2

13--18

PL

Step aerobics jest jedną z bardziej popularnych form rekreacji ruchowej. Uważa się, że podwyższenie wysokości stopnia, lub zaaplikowanie w choreografii kroków typu high-impact zwiększa poziom trudności i intensywność zajęć, a w konsekwencji bardziej obciąża układ ruchu, co często prowadzi do kontuzji. Siła reakcji podłoża jest jedną ze zmiennych, która dostarcza informacji o obciążeniach. Niniejsza praca zawiera podsumowanie wyników, podawanych w literaturze, dotyczących zmian sił reakcji podłoża podczas najczęściej wykonywanych kroków aerobikowych.

EN

Step aerobics classes are offered at many gyms and fitness centers. The step aerobics is distinguished from other forms of aerobics exercise by its use of an elevated platform (the step). The height can be tailored to individual taste by inserting risers under the step. The main objective of the paper is description of human movement and vertical ground reaction forces during common steps in a simple choreography on the base of the various articles.

15

Dynamic loads in some movement structures in acrobatics. A preliminary study

Dworak L. B., Twardowska M., Wojtkowiak T., Kmiecik K., Mączyński J.

Acta of Bioengineering and Biomechanics

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2005

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Vol. 7, nr 1

69-75

EN

The aim of the paper was identification of force-time characteristics of ground reaction forces exerted during take-off and landing phases in the six typical acrobatic elements. The tests of a pilot study character were carried out on two professional athletes aged 17 and I8. The levels of such parameters characterizing dynamic loads and overloads of examined movement structures as: maximal and average values of vertical ground reaction forces, total time of support phases, time necessary for generation of maximal force, force buildup indexes as well as force impulses were calculated. The results obtained suggest that dynamic overloads are serious and of traumatic character.

16

A study characterizing dynamic overloads of professional dancers. Biomechanical approach

Dworak L. B., Gorwa J., Kmiecik K., Mączyński J.

Acta of Bioengineering and Biomechanics

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2005

|

Vol. 7, nr 1

77-84

EN

Many jumps made in classical and modem ballet are responsible for serious injuries. A pilot experiment that was earned out with two professional dancers measured the temporary character of ground reaction forces in a few chosen elements of classical dance. The method of piezoelectric dynamometry as well as video recording were applied. The results of the experiment concerning the dynamic overloads, which are defined by the value of ground reaction forces, allow us to set the direction of a further research in the area of biomechanical interpretations.

17

Dynamic overloads during marching past gait

Dworak L. B., Kmiecik K., Mączyński J.

Acta of Bioengineering and Biomechanics

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2000

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Vol. 2, nr 1

71-75

EN

The paper presents quantities which characterise overloads during marching past gait obtained from the time curves of the ground reaction forces. The following quantities were interpreted: time of single support, time of strike, extreme values of ground reaction force in the sagittal plane, build-up force indexes and velocity of marching past gait.