Pupil Dilation

Pagina 1

PUPKLARYCONTROLSYSTEM Black- BOX symphatetic+ NON- LINEARSYSTEMLIGHT INTENSITY(±) EÉÉFÉ"") , Retina , CNS,@MIDBRAIN IRIS> × pretectun> """"""""" j Muscles^ NUCLEUS (= A.I ¥:L. (a) NotaCOMPLETE SYSTEMIDENTIFICATION *BLACK- BOXAPPROACH: r TheWhitemodelistoCOMPLEXtoProvidea detaileddescriptiomofeachComponent, soam INPVI- OUTPUTapproximatiomisconsideredlumpimg allComponentsinaSINGLEBlock * LINEARIZATION @Constantillumination: Ict)- Ir > EQUILIBRIUMPoint: (Ir,Ar) #= | (Ir,Ar) @VariationsaroundWP: Ict)= Ir+SI ' Alt)= Ar+SAwuere SL= ARSI+Irsa#a #, #= %ÌL.a, SIA) SL Thesystem}regulatesthePUPILDIMENSIONby→ ar > + > GCS)^- → GMPENSATINGa DECREASEinIIVIENSITY(SI<0) → withamINCREASEofPUPIL'SAREA(sa>0)Salt) Ir → toKEEPconstanttheFLUX(SL- -0) PARAMETERSARE EXPERIMENTALLY Ma. E ' » OBTAINED * I/O APPROXIMATIONProposerobyStarkandClynes: GCS)= : (1+25)} 3ELEMENTS: I gives(w)>-270' as w→ cs , ± GAIN: kle-i-ka.IR BUTsince HeisverySmau, E TRIPLESTABLEREALPOLE(@- %) FLLTF«1 w 㱺STABILITYE PUREDELAY(ofD) It givestheinfiniteCirclesconvergingtoMCW)= 0D=0.18s [=0.1s n HIGHLYSTABLECONTROLinNORMALCONDITIONS Noengineerwouldhavedesignedsucha CONTROLLOOP, butthisiswhatapparentiythebodyhascomeup withthroughoutevolution PATHOLOGICALor DRUGSINDUCEDCONDITIONS CRITICALFREQUENCYIdentification sincetheconsideredmodelispersèUNSTABLE(→ -270. ), butKEPTSTABLEthankstotheVERYLOWGAIN, am Interestingparameteris theCR. FREQUENCY, thatistheWethatgives(wa)= - 180. (theCrossingpointwiththenegativeaxis: ahu ) soitisthePointwheretheGAINMARGINis computer: %-1? GM= %LTF(wc) Wc µ,• Re >soWeistheFrequencyoftheSTEADYOSCILLATIONSthatwouldappear ifGAINwereHIGHER Kitee- IWD LTFCW)= ma (w)= arg(14# È" )- arg(1-3W'è+jwr(3-neri)). . (1+JWZ)} ⊥+jwr)> = 1+3(jwr)> +3ljwc)+(jwr)> = = - WD- fan' 1 (WZ(3- ✓%) = 1-3Wh' +3jwe-jwa.is=…