© ISO 2016 Prosthetics — Quantification of physical parameters of ankle foot devices and foot units Prothèses — Quantification des paramètres physiques des dispositifs de cheville/pied et unités pour[.]
TECHNICAL SPECIFICATION ISO/TS 695 First edition 2016-06-15 Prosthetics — Quantification o f physical parameters o f ankle foot devices and foot units Prothèses — Quantification des paramètres physiques des dispositifs de cheville/pied et unités pour les pieds Reference number ISO/TS 16955:2016(E) © ISO 2016 ISO/TS 695 : 01 6(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2016, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Contents Page iv Introduction v Scope 2 Normative re ferences 3 Terms and definitions Symbols and abbreviated terms Requirements Setup conditions 7 Quantification 7.1 Heel, mid-foot and toe characteristics 7.1.1 Procedure 7.1.2 Data collection and calculations 7.2 Roll-over characteristics 7.2.1 Procedure 7.2.2 Data collection and calculations 7.3 Torsional characteristic 7.3.1 Procedure 7.3.2 Data collection and calculations 7.4 Frontal plane characteristics 7.4.1 Procedure 7.4.2 Data collection and calculations Accessories 8.1 General 10 8.2 Procedure 10 8.3 Results 10 Annex A (informative) Quick re ference 1 Annex B (informative) Three dimensional locus o f force contact point on foot-sole Bibliography Foreword © ISO 2016 – All rights reserved iii ISO/TS 695 : 01 6(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso.org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html The committee responsible for this document is ISO/TC 168 Prosthetics and orthotics iv © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Introduction T h re e maj or fac tors contribute to fo o t de s ign: a) shape and size; b) strength requirements; c) functional performance Where — a) i s obviou s a nd defi ne d b y the fo o twe ar, b) i s s p e c i fie d i n I S O 2 re ferri ng to I S O 2 675 ( but i s no t s u itable — s ele c tion o f a s p e c i fic a n kle - fo o t device or prosthesis), and — fo o t for u s e a s a gu ide for the un it i n the pre s c rip tion o f a n i nd ividua l lower l i mb c) i s add re s s e d i n th i s Te ch n ica l Sp e c i fic ation The AOPA group of ISO/TC 168 members between 2006 and 2009 carried out work on a method to replace design criteria for prosthetic ankle-foot devices with compliance criteria which would be group “Testing” convened in Seattle, Washington and decided to work on a standard, based on the work of the AOPA group and other international groups The vision statement was: “To develop a standard app l ic able to b o th j oi nte d device s and u nj oi nte d device s with ela s tic elements I n 010 , the worki ng wh ich de s c rib e s quantitative me tho d s to eva luate or as s e s s key p er formance i nd ic ators o f pro s the tic an kle - fo o t device s wh ich a re correlate d to me a s u rab le pro s the s i s u s er b enefit.” T he s ub s e quent work on th i s ta s k h as made it cle ar that it s i s ts o f (at le a s t) two elements: fi rs tly, to develop a s ta nda rd wh ich de s crib e s quantitative me tho d s to eva luate or a s s e s s key p er formance i nd ic ators and s e cond ly, to i nve s tigate and attemp t to e s tabl i sh the correlation b e twe en the s e me as u re s and relevant me a s u re s o f pro s the tic u s er b enefit T h i s Te ch n ic a l Sp e c i fic ation de s crib e s s olely the quantitative me tho d s to eva luate or as s e s s key p er forma nce i nd ic ators T he fol lowi ng — “may” i s us e d to i nd ic ate that s ome th i ng i s p erm itte d defi nition s apply i n u nders tand i ng how to i mplement an I S O I nternationa l Stand ard a nd other normative ISO deliverables (TS, PAS, IWA) — “shall” indicates a requirement — “should” indicates a recommendation — “can” is used to indicate that something is possible, for example, that an organization or individual is able to something I n o f the I S O/I E C D i re c tive s , Par t (s i x th e d ition, 01 1) defi ne s a re qu i rement a s a n “e xpre s s ion i n the content o f a c u ment conveyi ng c riteri a to b e claimed and from which no deviation is permitted.” In 3.3.2 o f the I S O/I E C D i re c tive s , Par t (s i x th fu l fi l le d i f compl i ance e d ition, 01 1) defi ne s with the c u ment i s to b e a re com mendation as an “e xpre s s ion i n the content o f a c ument conveyi ng that among s evera l p o s s ibi l itie s one i s re com mende d as p ar tic u la rly s u itable, without mention i ng or e xclud i ng o thers , or th at a cer tai n cours e o f ac tion i s pre ferre d but no t ne ce s s ari ly re qui re d , or that (i n the negative action is deprecated but not prohibited.” © ISO 2016 – All rights reserved form) a cer tai n p o s s ibi l ity or cou rs e o f v TECHNICAL SPECIFICATION ISO/TS 695 : 01 6(E) Prosthetics — Quantification o f physical parameters o f ankle foot devices and foot units Scope This Technical Specification describes quantitative methods to evaluate or assess key per formance indicators of prosthetic ankle foot devices For each method, the set-up and test configurations are described Also included is a variety o f parameters which are derived or calculated from the recorded data 2 Normative re ferences The following documents, in whole or in part, are normatively re ferenced in this document and are indispensable for its application For dated re ferences, only the edition cited applies For undated re ferences, the latest edition o f the re ferenced document (including any amendments) applies ISO 10328, Prosthetics — Structural testing of lower-limb prostheses — Requirements and test methods ISO 22523:2006, External limb prostheses and external orthoses — Requirements and test methods ISO 22675:2016, Prosthetics — Testing of ankle-foot devices and foot units — Requirements and test methods 3 Terms and definitions For the purposes o f this document, the following terms and definitions apply heel, mid- foot and toe characteristics physical parameters to describe the response o f the ankle foot device under load a fter heel strike in mid stance and prior toe off 3.2 roll-over characteristics physical parameters to describe the sagittal plane properties o f the ankle foot device relevant for the patient during stance-phase 3.3 full contact motion physical parameter to describe the angular range o f motion o f the shin where the heel and the toe are in contact with the ground simultaneously torsional characteristic physical parameter to describe the rotational response o f the ankle foot device under load and additional torque in transversal plane 3.5 frontal plane characteristics physical parameter to describe the frontal plane response o f the ankle foot device during roll over on four different tilted ground angles in frontal plane © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Symbols and abbreviated terms Symbols and abbreviated terms are those used in ISO 10328 and ISO 22675 Requirements To determine comprehensive ankle foot device performance and to claim compliance with this Technical Specification, all parameters shall be quantified and the strength requirements specified in ISO 22523:2006, 4.4, shall be met I f an ankle foot device allows for di fferent adjustments on key per formance indicators, the manu facturer/submitter shall define the settings relevant for quantification To claim compliance with this Technical Specification, all parameters shall be quantified in the specific adjustments and the strength requirements specified in ISO 22523:2006, 4.4, shall be met Samples for the quantification shall be from the same production batch as those for strength testing I f not otherwise specified in this Technical Specification, the test preparation as described in ISO 10328 or ISO 22675 shall apply NOTE The order of tests given in Table A.1 minimizes the effort for test setup and configuration Setup conditions Use the coordinate system and test configurations specified in ISO 22675:2016, Clause 6, except P T is located at 700 mm height on a line which is located at midfoot and parallel to the u-axis The test methods specified are defined for a prosthetic foot o f size 26 cm and appropriate for a 70 kg amputee For all the described test methods, a force moment sensor shall be positioned above midfoot and at the height of 500 mm, see Figure In order to quanti fy the influence o f compliant components between knee and ankle foot device, the force moment sensor is positioned at a height of 500 mm A displacement sensor rigidly connected to the force moment sensor parallel to u-axis shall be used to record vertical displacement (su) An angular sensor rigidly connected to the force moment sensor perpendicular to u-axis shall be used to record the torsional angle (αu) Using the data acquired by the sensors, the following characteristics shall be calculated — Stiffness at static plate angle — Lever arm length at static plate angle NOTE D l l = (Δ Fu/Δ su) = (Mo/Fu) Calculations in ranges of Fu < 10 % Fumax to be considered carefully because of noise — Lever arm length changes at static plate angle Δ ls = l2 - l1 — E ffective foot length at tilting plate Δ llt = l2 - l1 — Full contact motion at tilting plate Δα = α2 -α1 © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) — E= E nerg y at s tatic p late angle — Torsional stiffness ∫ Dα = — Tors iona l angu lar nge Δα — E ffe c tive Δ fo o t width at ti lti ng plate u u F ⋅Δ (Δ M u = Δα lwt s u /Δα u2 u) -Δα = l2 - l1 u1 Figure — Setup 7 Quantification 7.1 7.1 Heel, mid- foot and toe characteristics Procedure Per form the qua nti fic ation figuration o f fo o t and of fo o t the he el , m id- fo o t pl at form de s c rib e d angles of -7,5° and 10° in addition (see Figure 2) T he p e a k force i n the lo ad i ng pro fi le for a nd for to e charac teri s tics u s i ng is designed The loading and unloading time shall be within (1 ± 0,1) s for wh ich the an kle Per form the quanti fic ation o f m id- fo o t ch arac teri s tic a s s tate d ab ove but with the force ma xi mu m b o dy weight i n the lo ad i ng pro fi le (s e e for shall be within (1 ± 0,1) s © ISO 2016 – All rights reserved ge ome tric a l quanti fic ation o f the he el and to e charac teri s tics (s e e sh a l l b e i n accordance with % (8 N ) o f the ma xi mu m b o dy weight (0 °) and the p e a k the lo ad i ng i n I S O 2 675 : 016 , 4.1 , u s i ng plate wh ich the a n kle fo o t fo o t Figure 3) fo o t device plate hori zonta l Figure 3) in accordance with 200 % (1 373 N) of the device i s de s igne d T he lo ad i ng and un lo ad i ng ti me ISO/TS 695 : 01 6(E) Figure 2 — Heel, mid- foot and toe characteristics (tilting angle o f foot platform) T he lo ad i ng pro fi le s l l b e a s i nu s oid a l wave with the p e a k at the s p e c i fie d lo ad Figure 3 — Loading profile 7.1 Data collection and calculations During the test, vertical displacement (su), vertical force (Fu) and outward moment (Mo) shall be recorded Using this data the following characteristics shall be calculated (see also Table 1) © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Table 1 — Heel, mid- foot and toe characteristics Tes t Parameter Measured signal/C alculated value 1) Stiffness 2) Lever arm length at Fu max Heel and toe 3) Lever arm length changes 4) Moment 5) E nerg y 1) Stiffness Mid-foot 2) Lever arm length at Fumax 3) 7.2 E nerg y Roll-over characteristics 7.2 Procedure Per form the quanti fication configuration o f fo o t and force of the rol l- over fo ot platform of F1cmax charac teri s tics (see Figure 4) using the geometrical ISO 22675:2016, 13.4.2, except Figure 5), and and the lo ading profi le des crib ed i n — applyi ng the — the du ration o f the lo ad i ng pro fi le s l l b e with i n 0 m s ± 10 % © ISO 2016 – All rights reserved b e twe en the pl ate angle s −1 ° and +2 ° (s e e ISO/TS 695 : 01 6(E) Figure 4 — Roll-over characteristics Figure 5 — Loading profile and foot platform angle 7.2 Data collection and calculations During the test, foot platform angle (α), vertical force (Fu) and outward moment (Mo) shall be recorded Using this data the following characteristics shall be calculated as shown in Table © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Table 2 — Roll-over characteristics Test Parameter Measured signal/Calculated value 1) Effective foot length Rollover 2) Full contact motion 7.3 7.3 Torsional characteristic Procedure Per form the quantification o f torsional characteristics using the geometrical configuration described in 7.1.1 (mid-foot characteristics) except that the vertical force (Fu) is applied at a constant level in accordance with 100 % o f the maximum body weight (687 N) for which the ankle foot device is designed (Figure 6) Apply the force profile as shown in Figure Apply a torsional moment o f −15 Nm to +15 Nm while the foot is under maximum load ( Figure 7) The torsional moment time shall be within (10 ± 1) s Figure — Torsional characteristics © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Figure 7 — Force and moment profile 7.3 Data collection and calculations During the test, torsional angle (αu) and torsional moment (Mu) shall be recorded Using this data the following characteristics shall be calculated as shown in Table Table — Torsional characteristic Tes t Torsion 7.4 Parameter Measured Signal/C alculated Value 1) Torsional stiffness 2) Torsional angular range Frontal plane characteristics 7.4.1 Procedure Per form the quanti fic ation o f the pro fi le s de s c rib e d i n 7.2.1, except fronta l pla ne ch arac teri s tics fro nta l Figure 8) using the setup and — sagittal-plane, — the he el dum my i s mou nte d i n the — characteristics, — the j oi nt i n the top lo ad appl ic ation p oi nt i s blo cke d aga i n s t ro tation ab out the u-a xi s the ti lti ng p l ate i s ti lte d s tatic a l l y i n the (s e e the fronta l fronta l p l a ne i n add itio n to the ti l ti ng mo vement i n pl ane angle on top o f the ti lte d plate, a ngle i s s e t i n an a ngle o f ± ° a nd i n an angle o f ±10 ° to quanti fy the me d i a l a nd latera l © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) a) Sagittal b) Frontal Figure — Frontal plane characteristics Figure 9 — Loading profile and foot platform angular range in sagittal plane 7.4.2 Data collection and calculations During the test, foot platform angle (α), vertical force (Fu) and forward moment (Mf) shall be recorded Using this data the following characteristics shall be calculated as shown in Table © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Table — Frontal plane characteristics Tes t Parameter Measured Signal / C alculated Value Frontal Plane Effective foot width 8.1 Accessories General Tors ion adap ters , s ho ck ab s orb ers , an kle un its a nd o ther a comparison test 8.2 fu nc tiona l comp onents c an b e te s te d by doi ng Procedure Clause using a relevant foot and the functional component Repeat the tests without the functional component Ru n the te s ts s p e ci fie d i n 8.3 Results C omp are the re s u lts i n order to quanti fy the 10 fu nc tiona l i n fluence o f the comp onent to the relevant fo o t © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) Annex A (informative) Quick re ference Table A.1 — Quick re ference Tes t a Test profiles Parameters Measured signal/C alculated value 1) Stiffness 2) Lever arm length 3) 7.1 E nerg y 1) Stiffness 2) Lever arm length 3) Lever arm length changes 4) Moment 5) E nerg y 7.3 1) Torsional stiffness 2) Torsional angular range 7.2 1) Effective foot length 2) Full contact motion 7.4 1) Effective foot width a T he o rder o f te s ts g i ven i n th i s tab le m i n i m i z e s the e ffo r t © ISO 2016 – All rights reserved fo r te s t s e tup a nd co n fi g u ratio n 11 ISO/TS 695 : 01 6(E) Annex B (informative) Three dimensional locus o f force contact point on foot-sole The force contact point, fcp, ( f1 , u1 , o1) is calculated as the cross point of line A (screw line calculated from the output of 6-axis load cell) and line B (swing foot plate surface) shown in Figure B.1 a) The origin is on the centre of 6-axis load cell Locus of the point ( f1 , u1 , o1) is corresponding to but not equal 2] The “roll-over shape” is the locus of cop (centre f of pressure) on the foot-sole in sagittal plane The force F and the moment M f f f F and the moment M p on the screw line shown in Figure B.2 f f M = Mp + Mr (B.1) to the “rol l- over s hap e” u s e d b y Re erence s [ ] and [ me as u re d by a -a xi s lo ad cel l are p o s itione d on the centre o cel l, and are e qua l ly tra n s orme d to the orce T he -a xi s lo ad cel l s hou ld b e clo s ely p o s itione d to the Mp = a ⋅ F M r = ra × F oot or h igher re s olution (B.2) (B.3) Mp / / F) ( ( the lo ad Mr ⊥ F) ( r − ) / / F then ( r − ) × F = (B.4) From Formula (B.2) and Formula (B.3), Formula (B.4) is transformed to Formula (B.5): r × F − M + ( a ⋅ F ) = Formula (B.5) is the screw line A, where r = ( f, u, o) t , F = ( Ff , Fu , Fo ) t , M = ( M f , M u , Mo ) t From the relation of Formula (B.6), a is calculated from Formula (B7): M ⋅ F = ( Mp + Mr ) ⋅ F = Mp ⋅ F = a ⋅ F ⋅ F M F +M F +M F M a = ⋅ F = f f u u o o F⋅F Ff + Fu + Fo From Formula (B.5) and Formula (B.6), the screw line A on each plane is expressed as follows — Sagittal plane ( f plane) fFu − uFf − Mo + aFo = – u — Frontal plane (u- o plane) uFo − oFu − M f + aFf =0 (B.5) (B.6) (B.7) (B.8) (B.9) When the 6-axis load cell is positioned as shown in Figure B.1 b), the screw line A on the sagittal plane is expressed as Formula (B.8) in which f is changed to f - fa This should be applied to Formula (B.10) 12 © ISO 2016 – All rights reserved ISO/TS 695 : 01 6(E) In Formulae (B.11), (B.12) and (B.13), f(t) should be changed to f(t)-fa In Formula (B.13), f1(t) should be changed to f1(t)-fa The equation of line B (swing foot plate) is expressed as Formula (B.10) from Figure B.3 and Figure B.4 u u = tanθ ⋅ f − u1 − TA,L + fTA,L tanθ (B.10) cos θ Then, line A and line B in sagittal plane are expressed as the function of time (t) Line A: f( t ) Fu ( t ) − u( t ) Ff ( t ) − Mo ( t ) + aFo ( t ) = (B.11) Line B: u TA,L + fTA,L tan θ ( t ) cos θ ( t ) u( t ) = tanθ ( t ) ⋅ f( t ) − u1 ( t ) − (B.12) From Formulae (B.11) and (B.12), f( t ) Fu ( t ) − tanθ ( t ) f( t ) Ff ( t ) + u1 ( t ) Ff ( t ) + u TA,L + fTA,L tan θ ( t ) Ff ( t ) − M o ( t ) + aFo ( t ) = cos θ ( t ) then, f1 ( t ) u TA,L − u ( t ) Ff ( t ) − + cos θ ( t ) = B y s ub s tituti ng lo c u s o f the (B.13) fTA,L tanθ ( t ) Ff ( t ) + Mo ( t ) − aFo ( t ) (B.14) Fu ( t ) − tanθ ( t ) Ff ( t ) f1 (t) for f(t) in Formula (B.12), u (t) is determined, and the locus of the point ( f1 , u ), the force contac t p oi nt on the fo o t- s ole i n the s agitta l plane i s fi xe d Screw line A in the frontal plane (u-o plane) is expressed as Formula (B.15) from Formula (B.8) u( t ) Fo ( t ) − o( t ) Fu ( t ) − M f ( t ) + aFf ( t ) = (B.15) B y s ub s tituti ng ( ) for u(t) in Formula (B.15), o1 (t) is determined, and the locus of the point ( f1 , u1 , o1), u1 t the th re e d i men s iona l lo c u s o f force contac t p oi nt on fo o t- s ole i s fi xe d One of the calculated results of three dimensional locus of force contact point on foot-sole is shown in Figure B.5 © ISO 2016 – All rights reserved 13 ISO/TS 695 : 01 6(E) a) Setup to derive the given formulae Key b) Alternative setup screw line (Line A) load cell (M, F) foot plate (Line B) force contact point fcp (f1 , u1 , o1 ) Figure B.1 — Principle to measure the 3D locus o f the force contact point on foot-sole Key screw line (Line A) Figure B.2 — Relation between output o f 6-axis load cell and screw line 14 © ISO 2016 – All rights reserved