BARTLETT, R.M.

BEST, R.J.

SAWYER, R.A.

English

ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive

JAVELIN FLIGHT SIMULATION-INTERACTIVE SOFTWARE FOR RESEARCH AND COACHES BEST, R.J.*+; BARTLETT, R.M.+ and SAWYER, R.A.* *Department of Aeronautical and Mechanical Engineering * University of Salford UK +Department of Sport and Human Sciences Creve+Alsager College of Higher Education UK AmRAcT &I interactive computer softvare package bas been developed that s h l a t e s  the fl ight of the men's new rules and ladies javelin's based on reasured aerdynaic  data. !be program includes user directed inputs of the most important variables in javelin throwing with a coaprebensive HELP section giving scientific knd mn-scientific descriptions of each variable as well as sets of realistic inputs to be used as a guide by t ie  user. The beer can assess the effects of small changes in each release variable in a may that i s  impxsible to control in the field without having to put athletes throqh ptentially hazardous experimentation. Tk extensive softwre graphics reveal a real-time simulated javelin flight based on the user's inp~;? release data. The flight graphics include a vindow vhich zoom in on the javelin showing important f1i;c: information, and essential past flight i n f o m t i ~  including sillulated distance Worn and landing angle. Plight graphics are followed by options to  dump infowtion on black and vhite or mlour printers, re-run the simulation in real t i r e ,  input new release data, calculate the opt iau  release conditions and range possibilities for that particular throver, or to  choose an extensive graph p lo t t i q  section. l?x graph plottinq routines allov observation of flight characteristics (e.g. velocity variation durinq flight) relatinq to the sinulation mst recently perforped. The col~ur  cded graph section is  an essential prerequisite for resear,:lr, coach, teacher, student, athlete and mufacturer since it can be used to develop a aectlanicai and aercdyc-:: understanding of the event. Additional sof tare  raterial incorporated includes 'unconstrained opt:aisa:i:n a l q o r i t h  ard I-dimensional contour mapplnq or isometric plotting using N# library routines vith the autacr;' extensive data libraries. In conclusion, the package pernits fine observations to be lade conparing different javelins acd s a i l  variations in athletic t e c h i p s  using applied optiml control theory. The progran bas been , w d  as ui ai3 t j  coaches, researchers, teachers, students, ranufacturers and, o! course, tbe athlete and i s  priaarily used as i n  aid i n  deve1:pinq an understanding of mis  complex throwing event. A central feature in e l i te  athletics i s  the problem of determining and elisinatinq errors in t e c b i p e .  m i s  has two prerequisites, firstly there needs to be an optimm performance lode1 to serve as a referenciiq system, and secondly variations from this Podel need to  be assessed quantitatively and rectified. Obviously t.?e latter cannot be attempted unless the former has been developed. In throwing events the ultinate perfomme . parameter, q e ,  i s  a function of the associated release conditions since tbe projectile's path cannot te affected by the thrower after release. During the airborne phase there are clearly defined gravitational and aerodynamic forces acting such that throvinq can be considered as an in i t ia l  (release) condition problen and the differential  equations that describe the trajectory of any thorn implement are of the forn: he re  f a t  release (t=ffi) is equal to f (0) (RJBEAM and RUST, 1984). From this i t  can be shorn that the complete trajectory, and therefore the range, of a throm inplemnt i s  already determined once the init ial  (release) cordition f (0) is chosen. The problem can be solved, and o p t h l  release conditions found, if javelin flight can be accurately simulated. The state vector f ,wnprises displacesents, angles, velocities ard angular velocities relating to the javelin at  any specified tm during flight. Sinilarly, (0) comprises displacements, angles. velocities ard angular velocities at  the instant of f VIII Symposium ISBS - 279 - Prague 1990 release, and since tbese are all datanined by tbe throw, tbere mst be optiml sets of initial (release) coditions for each athlete uhicb will produce a M X ~  range. Computer sh la t ions  of javelin flight are nov a coma feature in javelin research (e.g. EST, UiULETf and SUIYER, 1989; W and WYS, 1987), although the wide availability of s h l a t i o n  software i s  not yet w t .  I t  io tbe objective of this paper to pnscnt an inbmt ive  jrvelin flight sirmlatica software pacltagc for w by rescarchon, mnufactumr, teachers, coachrs and, of c a n e ,  athlete. Tbe defini t im that f o l l a a r e  based, ubaPcver pouible, on tbe mtrtion and axes system standarb put forward by BOPKM (1%6) and tk POY& %XEY (1967). All definitions relate to or about the javelin centre of gravity (a;). D Drag Lor-; tbe resolved aMdyMlic force acting parallel to tbc relative vind vector, V. g Gravitational Acceleration. Iy Ibnent of Inertia about the javelin's body axes y axis (pitch axis). L Light Force; the resolved aerodywic force acting perpendicular to the relative wind vector, V; i n  Z-dimsional simlation this lies in the earth axes rY plane. I Javelin kss .  W Pitchhq Ibaent; lbmt tendiq to rotate tbe javelin about its body axes y axis (pitch axis) in the XZ plane of the javelin body axes. q Pitch Rate; the angular velocity conpmnt in the XZ plane of the javelin body axes: In 2-dinensional simulation q = 0. R Range; horizontal distance from the a; at release (t=Os, x(0) = Om)  to the point &ere the the javelin f i s t  touches the qmund on landing. t Tine; t (0)  represents the instant of release. V Javelin CG Velocity with respect to air. VX Javelin CC Velocity with respect to earth. Vn ibdnal Velocity; the maxim release speed capability of a throwr at  = 35' (athlete specific). vw In this paper V, represents the air velocity relative to the m m l  earth borisontal x axis a t  a height of In; tailwind positive. Vx The colponcnt of VK along horizontal mml earth horizontal x axis. V, The conpment of Vg along the vertical now1 earth vertical z axis. x CC co-ordinate in the normal earth x direction (forwards positive). z CC co-ordinate in the m m l  earth z direction (upvards positive, unlike BOPKIN, 1966). dk Rue aerodyrmic Angk PI Attack with r s ~ t  to air; tbe angle between the javelinas x (long) axis and th projection of V on to the mraal earth rZ plm.  vIII Symposium ISBS - 280 - Prague 1990 ax Angle of Attack vith respect to earth; as a except Vx is projected instead of V (i.e. 6-Y in 2dimnsional siulation). y hqle of Climb; tbe direction angle of VI relative to the horizontal plane of tba n o m l  earth ares; y (0) = Angle of Release. B Inclhtion Angle; the attitudc angle betveen the javelin x (loq) axis and tbe horizontal plane of the mnal earth axes. (0) as in q(0) denotes a paraaeter value at tbe instant of release, t(0). Dot as in 4 denotes differentiation vitb respect to tile. Dash or prize as in q' denotes a perturbation. So= of the mre important variables for 2di~nsional mtion are sbom in Figure 1, where the above notation are conceptually simplified. Pigure 1: Soce important release variables VIII Symposium I S B S  Prague i990 I An ieportant assumption in present flight simlation research is that a l l  javelin activity in flight wars in a single vertical plane ( m m l  earth XZ p I m J ,  thus reducing tbp. pmblen to 6vo dimensions. This ars~@m is ryonablr(EUTL8E and BEST, 1988; EXlBWl, 1984). A 2 ~ 1 0 ~ 1  campuk a ida t ion  of javelin fliqht essentially m i s t s  of two stages. Firstly, a complete set of aerodpadc farm and monent data for the relevant r q e  of arrgles of attack and air  s p d s  encountered in javelin flight am reqaired. The vertical plane aetodynaric lwiel described !q EST and MTL.tlT (1988, 1989) fulfils tbe 2 d k 6 i o n a l  criteria involved. The second stage of the computer flight rimlation involves a .etbod for predictiag javelin position's aqles ,  velocities and w l a r  velocities a t  any h e  during the javelin's flight. There are sir differential equations of wtion to be solved (three f i rs t  order, x a 9 and three second order, x z 8 ). IJr;ing mrlier definitions, these sir differmtial equations can be expressed as first order by resolving, viz: and fo r  the atave to  be solved, four further equations are required since L,D,R = L,D,K(V,a) and a = 1: f ,8, VY); The differential equations are solved numerically usiq the Runge-Xutta 4tb order ~ L k d  (e.7. SCiUXN, 1386) vith L,D and K recalculated during each of the four steps, and al l  equations salved simal2necusly. Since x(3) = Om,  Ranqe can be expressed viz; = R(VK(0), 8 (01, aI((D), ¶(Dl, Z I O ) ,  VH) me above equation for Ranqe reveals the user input requirements for javelin fliqht simulations saltdare. The final assumption relates tb the fact that an athlete throe at  a different release speed, Vk/O), for each value of arqle of release, Y ( 0 ) .  The speed/anqle relationship used by the authors vas ca!culated by replotting the data of VIITASALO - and KORJJS (1388) and fittinq polynomials based on the principle of parsimy, such that: SOmm The coquter softdare presently runs on an Acorn Archimedes 300 and 400 series microcomputer and will soon be available on PC based sys-. T k  chosen p r q r d q  l a q g e  i s  structured BASIC V since BASIC i s  the mst papular and videly used prcq&ng language and the mst suited to the wide range of users for vboa the %fedare i s  vritten. VIII Symposium ISBS - 2 8 2  - Prague 1990 IM min pmqm h l a d t r  met dirrcted intrnctive keybxd hptc based on the aquation; with w adM inpllt all- a chob of IAN approcnd coqrtition javelins including lea's Apollo 1001 new m l u  javelin and ladies 60Og Apllo bmdp jamlin. This section of the program features a coqnhenrive U 5 P  section giving scientific and mm-scientific dcrriptianr of each wiab le  as well as sets of realistic in@ v to be used as a wide by the wu. Graphics diagrarr ua wd as w a d d i t i a l  aid dth, for e x a ~ l e ,  the r e l e v ~ t  wiable (e.g. q(0)) frol Figure 1 flarbing vbra tbr ntpain w t e r  value i s  to be entered. If a parark valw is entared tbat ia outride the ml mqe of values encountued in the javelin event th pser is given a caution and the option to enter a new value tor that variable. This is ane -1e of the m u s  debqqiq proxtdures designed to avoid a program crash. lost striking advantage of this section is that the user can urau the effects M mnge of wll c k q a  in each release variable separately in a way that is virtually iqussible to control in the field, and indeed, asws s n l l  changes in athletic technique in an applied sense vhen used in conjunction vith high speed cineratoqraphy (BEST, 1988). RELERSE PIRASTERS Release Height 211 ~oainal Uelocity 3 8 u s  Angle o f  Release 32' Rnqle o f  Rttwk (or) 1' True lnqle of Rttack (a )  - 1  7' Release Pitcn Rate 1; llind Speed 2u s ;a Landing inciination Angle = -58.2' Flight Time = 3 . 5 5 s  9 '' 3 18 28 38 48 58 63 79 88 98 180 RAHGE/* Pigwe 2: Post-flight javelin rimlation graphics Pollowing the user input section, colour graphics reveal r real-tim simlated javelin flight based on the user supplied release pameter data, cullinatiq in infomtion described in Figure 2. Fliqht grapbics include s a window zoolinq i n  on tbe javelin to rhov i t s  inclination and tbe direction of Vk. Finally, flight graphics are folloved by options to dmp infomtion into colav or black and ubite printen. I Since range can br accurately simlatad and the release variables Y ( 0 ) ,  a ( 0 )  and q(0) are optiaa variables ( B P S T , m  and SAWYW, 1989), ttvro urt k an o p t h l  set of tbese variakles for any given set of VN, z(O) and Vw, such that when ~ifferentiating witb respect to Range (R) ;  q(0)l = ~ ~ ( 0 ) '  = y ( 0 ) '  = 0 VIII Symposium ISBS Prague 1990 The o p t k b t h  algorithr &men for this software L th DSC mtbod ot Davis, Svam and Qqry (BOX,MVIES and SUET, 1x9). ?bh .method, an ex twim of and superior to Rombrockas method, is an wonstrained l h ,  direct search optinisation algorittm (unmnstrahd because the s w a t i o n  dces m t  predict f la t  landingr in either m ' s  or ladies javelin throvbq, the latter being a limitation of the resmcb being looked a t  ~ t l y ;  BEST, 1988). DSC ms chosen in prefer- to tbe mre w m n  awl quicker Po-ell's m W  because Poucllls rthod, ale being mst efficiant in tbr reqion of tbr optimm vharr tbr hmction (R) can be well appruximted by a ripbratic, can prom inefficient for coqLu ~oneyletricdl surfaces and vhn the starting p i n t  is a long way f m  tbe o p t h .  T k  htter is certainly a v i b i l i t y  since the initial g~er;8 or s t a r t iq  point is h.or the user input data. DSC ovucole~ tbese possible fncificiencies and i s  prcgraned within the softme in order to amqasa ndirmionitl optkiratim w l~ ,  h Wlideaa v&nr space, ud continuwly uslag arpbq -tion to redefine utually ortboaonrl direction vectors via Q1vScbridt ortborormalistim r e l a t h s h i p  (BIIUEOPP and W, 1966). This uvblu DSC to cope with the r i m  and skews of mre colqlex surfaces. Wition81 softare p m g r d  in  ANSI Forban 77 i s  also available alloving 3dixnsional contorn rapping aad i smt r ic  plottinq using )IK; library routines and the authors1 extensive data 1:craries. Figure 3: Lift, drag and pitchinq maent profile (Pig. 2 release data) me optimistion routine i s  folloved by a cboise to re-run the original simulation in real t h e ,  input new release data or to choose an extensive graph plotting section. Tbe latter allow observation of various fliqbt characteristics wing the authors' 5-point, colour coded graph plottiq routines. For example, Figure 3 shows tbe aercdyxdnic forces md mpents acting d u r b  tbe flight described in Figure 2, while Figure 4 rhovs pitch rate variatianr during flight, emphasizing the mu faailiar constant negative (rose dcvn) rotation of the mnls new rules javelin. The graph section i s  an essential prerequisite for researcher, coach, teacher, studa~t, athlete and mufacturer s h  it can be used to develop an understandinq of this complex aerody~lic  and VIII symposium ISBS - 284 - Prague 1990 mechanical throwing event. Fi jure  I :  Pixh rate profile (Pi?. 2 :e!ease Cat.) A jave!;l :light shu!ttion scf:i&re packaqe tds been developed 3s a rese3rch;:eanlg t x :  f: CXI!ZS, a:h!etss, research scientis:~, wx:xPxe:s and ~"ij~e:ii ty tejching cf 2 i i  coqlex a'3.:e(.ic e v a t .  The scfvdare includes rea!-ti= fliqht qra~hics,  a comprehensive HILP section, optinisa:ion 3: a'.n!eC? specific re!ease variables, meas9xed aeradynamic data and graphical flight analysis section. The main advantage of the pryraa i s  t,bt i t  an he used by the ccach t c  assess or, cozputer what i s  vr?nq with aspects of an athlete's technique vificut putting those athletes lirder potentidI!y ha:ar?:cs a p r i w n t a t i s n  in the field. REi'EENiES Mii?LbT, R.Y. and BEST, R.J. (1333) The biomech&?i:s of javelin t?~ovinq: a reviev. J .Spr t  Sciences 6 ,  1-33, s BEST, R.J. (1988) Hen's New k:es and Lddies Ldvelin : Aerodynamics, Flight Shulaticn aid Bioxchaniz; Ccnsiderations. Unpublished &ste:'s Thssis, Oriversity of Sdlfcrd, UK. Em, R.J. and BUTLFT, R.Y. (1498) Aerodynaaic chracteristics of nev rules javelins. In Eiomchanics in S p r i  , Institution c I  Xechanical Engineers, London, 13-10. 3251, R.J. 'and B A R T L F T ,  R . K .  (!963) Ladies javelin: aerodpanis,  flight sisulation and bioxchtnisal considerations. !n Biomecha;.;cs in Sport , He:!enic Sports Research Institute, Athens, 88-10), 3ES ,  R.J., &Wnt?T, R.I. and S A m ,  R.A.  (!333) Cocpter p r d i c t d  optim! release charxteristics f:r vary:" abili tf  %Le javelin throvers. In Pr%e+iinqs 6: the Xi1 International Conqres; of Biomechanics , KIA, n&r 270. VIII S p p o s i u m  ISBS - 285 - Prague 1990 BIMXOFP, C. and ~~, S. (1966) A Survey of Wem Uqebra. McMilian, Nev York. KX, I.J., DAVIES, D. d SSIJANN, W.B. (1969) Hon-Linear Optimization Techniques. Oliver and Boyd, Edinburgh. EOFKLV, B.R. (1966) A scheme of notation and namclature for aircraft dymaics and associated aerodynamics. RAE (Royal Aircraft Establishment) Technical Reprt TR 66200, parts 1-5. FJBJBBARD, N. (1984) Optiml javelin trajectories. J. Biomechanics 17, 777-787. E B W ,  I. and ALAWAYS, L.W. (1987) Optilaal release conditions for the new rules javelin. Int. J. Spr t  Biosechanics 3, 207-221. c H;BW, I. and RUST, R.J. (1984) Simulatim of javelin flight llsinq experimental aerodynamic data. J. BioPecbanics 17, 769-776. RCYAL AER0MIC.U SOCIFI'Y (1967) mineering Sciences Data Unit (PSC3 Aeronautical Series), Ites nuhers I 67331, 67002, 67003 and 67037. Royal Aeronautical Society, London. XFM9N, R.E. (1986) Basic Numerical Hethods. Edward mid, London. VIEAX, J.T. and IORTOS, T. (1988) On-line m s u r e m t  of kinepatic characteristics for the javelin. In Bi3whdnics XI-B (editedhy C. de Crwt, A.P. Bollander, P.A. Euijinq and C.J. van Inqen Schenau), Ree 0c:venity Press, bterdar, 582-587. T?.e a!:thors wish to acknowledge the Financial support of tbe British Sport Council, without vhich this research ,auld not have been possible. V I I I  Symposium ISBS Prague 1990 

JAVELIN FLIGHT SIMULATION-INTERACTIVE SOFTWARE FOR RESEARCH AND COACHES

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JAVELIN FLIGHT SIMULATION-INTERACTIVE SOFTWARE FOR RESEARCH AND COACHES

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ISBS (International Society of Biomechanics in Sports): Conference Proceedings Archive