A Force Platform Free Gait Analysis

Transcription

1 Poceedings A Foce Platfom Fee Gait Analysis Tokio Maeda 1,2, *, Tatsuo Ishizuka 3, Sakua Yamaji 4 and Yuji Ohgi 3 1 Keio Reseach Institute at SFC, 5322 Endo, Fujisawa, Kanagawa , Japan 2 Koseki Gakuin Touto Rehabilitation College, Ohashi, Meguo, Tokyo , Japan 3 Gaduate School of Media and Govenance, Keio Univesity, 5322 Endo, Fujisawa, Kanagawa , Japan; tatsu47@sfc.keio.ac.jp (T.I.); ohgi@sfc.keio.ac.jp (Y.O.) 4 Faculty of Envionment and Infomation Studies, Keio Univesity, 5322 Endo, Fujisawa, Kanagawa , Japan; sakualennon@gmail.com * Coespondence: tokio3813@gmail.com; Tel.: Pesented at the 12th Confeence of the Intenational Spots Engineeing Association, Bisbane, Queensland, Austalia, Mach Published: 24 Febuay 2018 Abstact: Using multiple cameas with foce platfoms is a classical and popula method fo gait analysis. Howeve; it is difficult to measue natual walking; because the subjects have to adjust thei steps to place on the foce platfom. This study poposes two igid body linked segment models to estimate the joint foce and gound eaction foce without foce platfom. In ode to validate the accuacy of the models; the authos compaed thei kinetic paametes with those of classical model. The esults showed that the poposed models could estimate the gound eaction foce and the joint foce with high accuacy (less than 10% in the thid quatile on all axes). In addition; using the cente of pessue fom foce platfom could also estimate the joint toque with high accuacy. These esults suggest that we can analyze the gait without foce platfom; if the cente of pessue is povided in the futue. Keywods: gait analysis; igid body linked segment model; uppe body abbeviated model; foce platfom fee; kinetics; joint foce; joint toque; gound eaction foce 1. Intoduction In ode to analyze human gait, combination of optical cameas and foce platfoms is a popula and classical method in biomechanics. When the expeimente foces subjects walk in the laboatoy, it is difficult fo them to step onto the foce platfoms in thei natual walk. Usually, they have to adjust thei step length fo the pe-defined foce platfom alignment. Some of pevious studies had measued the pessue distibution o estimated a vetical component of gound eaction foce using a pessue senso on the floo o attached pessue sensos undeneath the shoes. Howeve, in those studies, since the pessue senso could output only vetical foce component, it is not sufficient fo the kinetics appoach [1,2]. Recently, motion captue system with/and miniatue inetia senso device has been epoted in the field of medicine and ehabilitation. Howeve, most of the cases, physiotheapists s assessment has been limited fo the kinematical issue not fo the kinetics one [3,4]. Since, the kinematics is the esult of the motion, fom the viewpoint of the causal association, the cause of the motion is obviously muscula foce and extenal foce acting to the human body. Theefoe, fo the deep insight of the walking, kinetic appoach must be necessay. Thus, the pupose of this study was to popose a gait analysis methodology which is foce platfom fee and validate the accuacy of its esult of the kinetics compaing to the classical model. Poceedings 2018, 2, 207; doi: /poceedings

2 Poceedings 2018, 2, of 6 2. Rigid Body linked Segment Model 2.1. Classical Rigid Body Linked Segment Model fo Lowe Limbs A classical igid linked segment model is only fo lowe limbs (Model A) (Figue 1 left). In ode to identify segment s joint foces and toques on the stance leg, this classical model equies gound eaction foce by the foce platfoms Full Body Rigid Body Linked Segment Model without Foce Platfom Fo the full body igid linked segment model (Model B), the authos divide human body into 15 segments, then solve the equations of motion fom the teminal segments except stance side lowe limb (Figue 1 middle). An advantage of Model B is to allow us to solve the joint foce and toque without using foce platfoms. A disadvantage is that it is impossible to solve joint foces and toques duing the double suppoting peiod Uppe Body Abbeviated Rigid Body Linked Segment Model without Foce Platfom A full body igid linked segment model abbeviating the uppe body (Model C) is ou second poposed model (Figue 1 ight). The authos suppose segments of uppe body as one single segment. An advantage of this model is that we can educe the numbe of segments fo the calculation, then it leads us to educe eflective makes in the expeiment. On the othe hand, a disadvantage of this model is that the integation pocess fo uppe body segments into one single mass might be ove o unde estimation of the total uppe body kinetics in asymmety motion. Fo all models, the inetial paametes wee efeed Ae [5] and Okada [6]. Gx 1 1p F 1 τ 1 τ 7 τ 4 16p F 7 2pc 7p Gx 2pL 7 7d 2d F 8 F 9 τ 9 Gx 9 8p 8d τ τ 3 8 9p 3p Gx 8 Gx 3 3dR F 4 4p Gx 4 2pR Gx 2 4d τ 5 5p F 5 F 3 Gx 5 5d τ 6 Gx 16 F 10 16dR 16dL Gx 10 F 10 10p τ 10 τ 13 13p F 13 Gx 10 3dL F 6p 10 10p τ 10 τ 13 13p F 13 F 6 Gx 6 Gx 10 10p τ 10 τ 13 F13 13p 10d Gx 13 13d Gx 12 10d 10d Gx 13 13d Gx 13 13d F 11 τ F τ Gx 11 11p F Gx τ p τ F p 14p 11d Gx 14 14d 11d Gx 14 14d Gx 12 F 12 F ga τ 15 F 12 Gx 12 F ga τ 15 τ 12 12p 15p τ 15p 12 τ 15d F 12p 15 15d F 15 z Gx 15 Gx 15 F 11 τ Gx p τ 14 11d Gx 14 F 12 F ga τ 12 12p left: Model A middle: Model B ight : Model C F 14 14p 14d τ 15 15p 15d F 15 Gx Expeimental and Analysis Method Figue 1. Rigid body linked segment models. Motion Captue System (Vicon MX T-20) and foce platfoms (Kistle, 9281C) wee used. Nine voluntee eldes (71.6 ± 7.2, 5 males, 4 females) wee ecuited fo this study. Subjects walked in the laboatoy setting condition which had 5 m staight couse with two platfoms. They wee asked to walk natually. Then thee to fou successful data which the subjects wee able to place thei steps on the foce platfom wee analyzed. The authos examined only one single suppoting peiod by thee diffeent models. Fo the assessment of the diffeence between models, we examined absolute value of the diffeence D, D = A(t) B(t), and the atio of the diffeence E, E = A(t) B(t) / Max(A) Min(A) 100 (%). Hee

3 Poceedings 2018, 2, of 6 A(t) is the standad time seies and B(t) is the compaing time seies. In this study, we used the classical model (Model A) as A(t) and compaed poposed Model B and Model C as B(t). This study was appoved by Keio Univesity Shonan Fujisawa Campus ethics committee in 19 May Results The joint foces on the hip wee calculated by thee diffeent models with espected to the local coodinate system of the thigh. Figue 2 shows examples of hip joint foces calculated by thee models duing one single walking cycle. In Figue 2, time seies of Model A, Model B and Model C show simila patten duing thei single suppoting peiod in both sides. Axis-I and Axis-J in the figues ae the medio-lateal and anteo-posteio axis espectively. Then Axis-K was along with the longitudinal axis of the segments. Figue 2. Compaison of Hip joint foce. * DSP: Double suppoting peiod. The absolute diffeence between Model A and Model B was less than 50 N and its median is about 14 N in Axis-K, which is along with the longitudinal axis of the thigh. As fo othe axes, the medians of absolute deviations wee less than 10 N. On the othe hand, the atio of the diffeence shows less than 3% in Axis-K. It means that the magnitude of the joint foce on Axis-K in hip was emakably lage than othes. Convesely, the absolute diffeence of the joint foce component on Axis-I and Axis-J wee smalle than that of Axis-K, but its diffeence atios wee lage than Axis-K s one. Similaly, lagest absolute diffeence between Model A and Model C can be seen also in Axis-K, and its atio of diffeence is smallest. Figue 3 shows the hip joint toques calculated by thee models. We can see lage deviation of the magnitude of joint toque on Axis-I (Flexion/Extension) athe than those of Axis-J and Axis-K. Although, Model B and Model C could estimate gound eaction foce with high accuacy in the single suppoting phase. Theefoe, the location of the cente of pessue should be identified fo ou futhe investigation. Nishikawa [7] mentioned that fee moment τ z can be small enough to neglect in case of walking. Theefoe, the authos decided to neglect fee moment τ z in this study and calculate the joint toques of lowe limbs. F ga is the gound eaction foce calculated by Model C without foce platfoms. Then, in ode to impove accuacy of the toque estimation, we calculated joint toques (Joint Toque D) of the lowe limbs using the cente of pessue measued by the foce platfoms and the gound eaction foce by calculated by Model C (abbeviated uppe body model). Figue 4 shows the estimated esult of the hip joint toque, Joint Toque D. While thee had been emakable deviation of the hip joint toque between Model A and Model B/Model C (Figue 3), Figue 4 shows that the esults of this stepwise estimation with the location of the cente of pessue was impoved.

4 Poceedings 2018, 2, of 6 Figue 3. Compaison of Hip joint toque. * DSP: Double suppoting peiod. 5. Discussion Figue 4. Compaison of Hip joint toque. * DSP: Double suppoting peiod. Model A, the classical invese dynamics model of lowe extemities used the gound eaction foce and its location of the cente of pessue fo the extenal moment by the gound eaction foce. Then we calculated joint foces/toques of single suppoted stance leg fom the foot segment towad hip joint. In geneal, this pocedue has been believed the gold standad method in the biomechanics [8]. In this study, in ode to validate accuacy of the esults of Model B, full bodied invese dynamics and Model C, full, but abbeviated uppe bodied invese dynamics model, we evaluated the deviation of the calculated foces/toques between Model A vesus Model B, Model A vesus Model C. In geneal tendency, both of Model B and Model C could well estimate the joint foces and toques. Howeve, the magnitude of those eos was depending on the segment axis. The lagest eo can be seen in Axis-K, which is along with the longitudinal axis of the lowe extemity. Axis-I and Axis-J ae the anteo-posteio and medio-lateal axis of the thigh espectively. Since those axes component of the load wee much lowe than that of Axis-K, the maximum eo was always shown in the Axis-K. Howeve, the atio of eo was smallest in Axis-K convesely. The authos ecognize seveal causes fo those eos which deviated fom the Model A. Both of poposed model, Model B and Model C equie the sequential calculation of the equation of the motion fom the distal end segments of the uppe extemities, head o abbeviated uppe tunk. In those calculation pocess, the accumulated eos might esult in the total eo. Since ou validation between thee models used same obtained motion captue data set, the eo cause should be model dependent. Fo example, the estimation of

5 Poceedings 2018, 2, of 6 the moment of inetial of the composite segments. At this moment, we could not identify a concete eo eason. Howeve, even though the gait cycle of the subjects wee fluctuated 10 to 20% within the expeimental tials, the mean eo atio was less than 10%. In addition, the eos and its atio of Model B and Model C wee almost the same. Thus, the authos can popose that Model C is the appopiate and convenient model fo the eal gait analysis situation because of its simple setting. At this moment, we could not identify a pecise eason of the deviation of the hip joint toque on the single suppoting leg between Model A and Model B/Model C, while the joint foces wee well pedicted. In ode to solve those eo in the joint toques, we examined hip joint toque of the single suppoting leg by the classical lowe body model (Model A) with estimated gound eaction foce by the Model C and the cente of pessue location which was measued by the foce platfoms. The calculated hip joint toque esult was impoved athe than those of the esults by Model B and Model C (Figue 3). Theefoe, if we took the incemental steps fom the abbeviated uppe body model (Model C) fo the gound eaction foce estimation, then the classical lowe body model (Model A) with only the location of the cente of pessue, the joint toques can be well estimated. Thus, the altenative of the foce platfom, such as the pecise pessue senso mat/capet will be expected in the futue. 6. Conclusions In this study, we examined thee of mathematical models fo the gait analysis. Table 1 shows the usefulness, possibility and the pe-equisite of each model. As a esult, the authos concluded that ou poposed abbeviated uppe body model, Model C can be used with satisfied accuacy and convenience in the expeimental configuation. Because, Model C equies additional one single eflective make to the classical lowe body model. This additional one make would be the epesentative of the uppe body. Also, whole bodied abbeviated model, Model C do not equie foce platfom. That means a gait analysis on the stai o even the outside ough teain can be achieved by this model. Howeve, in this study, since we calculated the lowe limb joint toques using the location of cente of pessue obtained by the foce platfoms, we need a futhe investigation the equipment o method fo measuing of the cente of pessue fo the impovement of joint toque estimation. Table 1. Usefulness, availability and pe-equisite of each model. Classical Model Full Body Model Abbeviated Model Numbe of makes ++(12~20 Points) -(30~40 Points) ++(13~21 Points) Estimation of Hip joint foce Estimation of Hip joint toque + Conditional Conditional Estimation of joint foce and joint toque in the Uppe limbs Measuement of gait with a cane + Conditional Conditional Measuement on the stais Conditional + + Measuement on the ough teain : Extemely useful; +: Useful; Conditional: conditionally useful ; -: Impossible. Refeences 1. Miyazaki, S.; Iwakua, H. A Device fo Continuous Measuement of Vetical Foot Foce duing Walking. Jpn. J. Med. Electon. Biol. Eng. 1977, 15, Oda, J.; Yasuda, A. Dynamic Analysis of Nomal Walking by Foot Pessue Distibutions. Tans. Jpn. Soc. Mech. Eng. Se. A 1991, 57, Sakuai, S.; Sakamoto, M.; Nakazawa, R.; Kawagoe, M.; Kato, K. Investigation of the Repoducibility of a 3D Acceleomete-Based Gait Analysis System of the Tibia. Soc. Phys. The. Sci. 2010, 25, 7 12.

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