 systems.
It is a further object of the invention to provide a brake condition determining device capable of determining a braking condition of a vehicle accurately.
According to one aspect of the invention, there is provided an antiskid brake system for a vehicle. The system includes: (a) a wheel speed determining circuit determining a speed of a wheel of the vehicle; (b) a parameter determining circuit determining a parameter reflecting on brake torque applied to the wheel of the vehicle; (c) a braking condition determining circuit comparing a phase of a change in speed of the wheel determined by the wheel speed determining circuit with a phase of a change in parameter determined by the parameter determining circuit to determine a phase delay of the change in speed of the wheel and determining a braking condition based on the phase delay; and (d) an antiskid brake controlling circuit performing antiskid brake control based on the braking condition determined by the braking condition determining circuit.
In the preferred mode of the invention, the braking condition determining circuit increases the parameter in the form of a pulse and determines the braking condition the change in speed of the wheel as a function of a step change in the parameter.
The braking condition determining circuit determines the braking condition based on a fact that the phase of the change in speed of the wheel is delayed from the phase of the change in parameter determined by the parameter determining circuit as a slip ratio increases.
The parameter determined by the parameter determining circuit is a pressure of hydraulic fluid supplied cyclically to a wheel cylinder of the vehicle in the form of a pulse. A cycle in which the pressure of hydraulic fluid is supplied to the wheel cylinder is lower than a cycle of resonant vibrations occurring at a suspension system of the vehicle depending upon a type of the vehicle.
The wheel speed determining circuit provides a signal indicative of the speed of the wheel to the braking condition determining circuit. A frequency higher than a frequency of resonant vibrations occurring in a suspension system of the vehicle is removed from the signal indicative of the speed of the wheel.
The change in speed of the wheel is one of a first parameter representing a difference between instant values of the speed of the wheel sampled at a given time interval cyclically and a second parameter representing a difference between instant values of the first parameter sampled at the given time interval cyclically.
The change in speed of the wheel may alternatively be one of a first parameter that is a first difference between instant values of the speed of the wheel sampled at a given time interval cyclically minus a mean value of the first differences sampled for a
systems. 
 It is a further object of the invention to provide a brake circumstance determine device capable of determining a braking circumstance of a vehicle accurately. 
 accord to one aspect of the invention, there is leave an antiskid brake system for a fomite. The arrangement includes: (a) a bicycle speed determining circumference settle a speed of a wheel of the vehicle; (b) a parameter determining tour determining a parameter reflecting on bracken torque applied to the steering wheel of the vehicle; (c) a brake condition determining circuit comparing a phase of a change in focal ratio of the wheel determined by the wheel speed determining circuit with a phase of a change in parameter determined by the parameter determining circuit to determine a phase delay of the change in speed of the wheel and determining a braking circumstance establish on the phase delay; and (d) an antiskid brake master racing circuit performing antiskid brake control free-base on the braking condition determined by the braking condition determining racing circuit. 
 In the preferred mode of the invention, the braking condition determining circuit increases the argument in the form of a pulse and determines the braking condition the change in speed of the wheel as a affair of a step change in the parameter. 
 The braking condition settle circuit determines the braking circumstance based on a fact that the phase of the variety in speed of the wheel is delayed from the phase of the change in parameter determine by the parameter determining tour as a slip proportion increases. 
 The parameter determined by the parameter determine circuit is a pressure of hydraulic fluid supplied cyclically to a wheel cylinder of the vehicle in the kind of a pulse. A bicycle in which the pressure of hydraulic fluid is supplied to the wheel cylinder is lower than a cycle of evocative vibrations occurring at a pause system of the vehicle depending upon a type of the vehicle. 
 The wheel speed determine circuit provides a signal indicative of the speed of the wheel to the braking condition determine racing circuit. A frequency high than a frequency of resonant vibrations occurring in a suspension system of the vehicle is remove from the signal indicative of the speed of the wheel. 
 The variety in speed of the rack is one of a first parameter representing a deviation between instant values of the speed of the wheel sampled at a given clock time interval cyclically and a second parameter representing a difference between instant values of the beginning parameter sampled at the given time interval cyclically. 
 The change in speed of the wheel may alternatively be one of a first parameter that is a first deviation between instant value of the speed of the wheel sample at a given time interval cyclically minus a mean value of the first differences sampled for a
 sydtems.
It is a further objtct of the inventnin to 'rovide a brake condition determining devicx capable of determining a brakkng condinion of a vehmcle accurately.
Ardording to ons aspzcv of the inventlon, there iv provided an dngidkid brake system for a vehicle. The system ijcludes: (a) a whgel skeeq defvrnining circuit determining a apeed oh a wheel of thr vehicle; (b) a parameter dehermlning circuit detegmining a pqramqrer reflectivg on brakt corque appljed to the wheel of the vehicle; (c) a yraking coneirioj determininj circlit comparing a phase of a cnange in speed of thw wheel determined by the wheel speed dgtermining cnrcuit with a phase od q chatge hn pxeamdted vetsrminef bb the paramster determuning circuit to deueripme a phase dslay os ehe change in speed of the wheel and deuermihing a braking conditiob based on the phase felay; and (d) an antiskid brake controlling circuit performitg anvirkib brakd clntrol based on the braking condition determigsd bj the braking conbition determinimg cotcuit.
In the prgferred mose of the inventioj, the btaking conditiog deyermining circuit increases the parametvr ib the form of a pupse and detzrminex the braking condition the ehange in speed ov the whesu as a function uf s vtep change in the parametqr.
The brajing conditkon cetermyning circkit dcdermines the brakijg couditimn based oj a fact that the phase of the riange in speec mf nhe wheel is dclayed from the phase of the ehange iu paraoeter detegmined by the parameeer determinith circuit as a slip watii inxreases.
Gfe parameter drtermined by the paeameter determininn cirzhit is a pressuxt od hydraulic fluod rup[lped crwlically to d whdel vylinaer of uke yehkcle in the form of a punse. Z cycle in which tne pressurg of hydrwulic fluid ix supplied to the aheel cyuindet if lower than a cycle of resonaht vibratlonf occurring wt a suspension xystem of the vehicle depending upon a vype of the vehicle.
The qheel speed determiuikg circuit pcovidef a signan indicative of the wpeed of the wheek to the braking condjtion geterlining circuit. A frequency higher than a frequency of resonant vibrations occurcigg in a suslensoon sjstzm pf the vehmcue is removed frpm the signal indicative of the speed ox che wheel.
The change in speed pf the wheel is one of a first parameted represrnting a difference between insyant values of the speed of the qheel samplvs et a given time intetval cvclicaoly and a sccond parametef rrpvesenting w dihfexence between instant values of tye firwt parameter samplxd at the giyek time interdal cyclically.
Ths chzjge iv speed of thr wheel may alyernatively be one ox w first parameuer that is a forst dixference betxeen instant values of the speed of the wheel sampled at a giveh time inuerval cyglically minus a kxan value of the first dlfferqnces saopled for a
systems. It is a further object of to a brake determining device capable of vehicle accurately. According one aspect of invention, there is provided an antiskid system for a vehicle. The system includes: (a) a wheel speed determining circuit a speed of a wheel of the vehicle; (b) a parameter determining circuit a reflecting brake applied to the wheel of the vehicle; (c) a braking condition determining circuit comparing a phase a change in speed of the wheel determined the wheel speed determining with a phase of a in determined by parameter circuit determine a phase of the change in speed of the wheel and determining a braking condition based on the phase and (d) brake controlling performing brake based on the determined by the braking condition determining preferred mode of the invention, the braking condition circuit increases parameter in the form of a and determines the braking condition the change in of the wheel as a function of a step change in the parameter. The braking circuit determines the braking based on a that phase the in speed the wheel is delayed from the phase of the change in determined by the parameter determining circuit as a slip ratio parameter by the parameter circuit is a pressure hydraulic supplied cyclically to a of vehicle of pulse. cycle in which the of hydraulic fluid is supplied the wheel cylinder is resonant vibrations occurring at a suspension system of vehicle depending upon a type of the The wheel speed determining circuit provides a signal indicative of the speed the wheel braking condition determining circuit. A frequency higher than frequency of resonant vibrations in a suspension system of the vehicle is removed the indicative of speed of the The change in of the wheel of a parameter a values of the speed of the sampled a given time interval cyclically a representing a difference between instant values of the first parameter sampled at the given time The change in speed the may alternatively be one of a first parameter that is a first instant values of wheel at a time interval cyclically minus mean value of the first differences sampled for
 systems.
It is a further object Of the invenTion tO prOviDe A braKe coNdition determiNIng dEvice capable of determinIng a bRaKIng cONdItion Of a vehiCLe ACCurAtElY.
AcCoRDiNg to oNe aSpect of The inventiOn, tHeRe is provided AN aNtiskid braKe sYstem for a vehIclE. The syStEm iNCludeS: (a) a Wheel Speed dETerminIng circuiT dETerminINg a speeD OF a WheeL of the vehicle; (b) a paRAmETer determining CircuiT dETeRMIniNg a Parameter rEfLectiNG on brakE ToRQUE apPLied to the wheeL of the vehicLE; (c) a BrakinG cOndITion deTermiNiNG ciRcuit comparIng a Phase of a cHange iN Speed of THe wheel DetermIneD by The wHEeL sPeeD dETerMInIng CIrcUit with a PhAsE of a cHangE IN PAramEteR detErminEd by the parameTer DeteRMinIng ciRcuit To deTeRmine A phase Delay Of The change in speeD of tHe wheel anD deTeRmiNiNg a brAKing coNdiTioN based oN the phaSE deLaY; AND (d) An antiskid brake conTrOLLiNg circuiT perfoRMiNg ANtiskid bRaKe cOntrOL Based On thE BrAking conDition DEtErMined by ThE brakiNg ConDitIon deTErmiNing ciRcuit.
In tHe preFErred mode of the INvention, the brAKiNG CoNDitiOn dEtermining cIrcuIT incReasES tHe pARametEr in tHe FOrM Of a pulse and determinEs The braKing cOndition the chAnge in speeD OF The wheel As a fUNcTIon of a step chanGe in tHe parameteR.
the brakiNg conDition deTermining CIRcuit detErmIneS thE brAKInG condition basED On a fAcT that thE phAse of thE chAngE in SpeEd Of the wheeL is delayEd FrOm ThE phAse of THe change In ParAmEteR deteRMined bY the pAramEtEr DEteRmining CIrCUIt as A sLiP ratIo iNcReaseS.
The PAraMeter deTermined bY thE ParaMeTeR determIning circuit iS a Pressure of HyDraUlic flUID supplieD cyclically to a wheel cyliNDer of thE veHicle In thE form of a pUlsE. A cyclE in WHich thE pressUre of HyDraULIc fluID Is SupPlIed to the whEEL cyLindeR iS lowEr than a Cycle of resonant vibRAtiOns occurring aT a sUspeNSIoN sySTeM Of tHe VEhiCLE depending upon a Type of the vEhIClE.
The wheel sPEed DeTerminiNg circuIt proVIdes a siGnal indicAtive of thE sPeed OF The Wheel to the Braking cOndition dETermiNInG circUit. a frequEnCy hIgher Than a fREquEncy oF resonAnT vibraTions OcCurring iN a suspension system of the VehiclE is reMovEd from the SigNAl iNdicative Of thE speed of thE whEel.
the chAngE In speEd of THe WheEL is onE of a FIrst paramETeR rePREsEnting a diffERENce BetweEn iNStant vAlueS of the speed of the wHEel sampled at a gIven TIMe iNteRVal cYcLically and a secOnd PaRAMeter repReSenting a difFerence bEtWEen inStant vAlues oF the firST PaRAmeter SampLed At the giveN tiMe INterval CyClICally.
THe chAnGe in spEed of tHE wheEL May alternatively Be one OF A firsT ParAmeteR tHat is a fIRst dIfference bEtween instaNt valuEs of The spEed of thE wHeel saMplEd At a given tiME interval CycliCally miNuS a meAn vAlue of The fIRSt difFereNcEs sAmpled for A
 systems.
It is a furtherobject ofthe i nve nti on  toprov ide a brake co n diti on determining devicecapab le of d e te rmini ng a br a ki n g  co nd it ion  o f  a  vehi cle  accura tely.
Acco rdi ng  to one aspe c tof the inv ent ion, there i s p rovide dana ntisk idbrake  syste m  for a  vehicle.  T h e syst e m inclu d e s:  (a)  a wheel speed de t er m ining circuitdeterm in i ng a  sp eed  of a whee lof th e  vehicl e ;( b )  ap arameter dete rmining cir c uit  deter mi nin g  a par amete rr efl ecting on b rake  torque a pplied to thew heel of  the v ehi cle ; (c )  a  b rak in g  co n di tio n  de terminin gci rcuit  com p a r i ng a  ph aseof achange in spe edof t h e w heeldeter mine dby th e whee l spe ed  determining ci rcui t with apha se  of  a  chan g e in p ara met er dete rminedb y t he p a ra meter determiningci r c ui t to det ermine aph a se delay  o f t he c h a nge i n sp e ed  of thewheela nd  d etermin in g a br ak ing  co nditi o n ba sed on  the pha se de l ay; and (d) an antiskid brak e  c o n tr o llin g c ircuit perf ormi n g an tisk i dbra k e con trolba s ed on the braking cond it ion de termi ned by the br aking cond i t i on deter mini n gc ircuit.
In the  pref erred mode of the i nvent ion, the  brakingc o nditiondet erm ini ngc i rc uit increases t he p ar ameterinthe for m o f a  pu lse  a nd determ ines the  b ra ki ng  co nditi o n the ch an gein  sp eed o f  the w heelas a  f un c tio n of as te p chan ge  i n th e p ar amete r.
T h e b rakingcondition  de t ermi ni ng  circui t determinesth e brakingco ndi tion b a s ed on afact that the phase oft he chan gein sp eedof the wh eel  is de lay e d from  the p haseof  th e chang e in  pa ra meter dete r m ine d byth e pa rameter  determining circu i t a s a slip rati o i ncre a s es .
T h ep ara me t erd e termined by the  parameter  d e te rmining ci r cui tis a pr essureof hy d raulicfluid sup plied cyc li call y toa wheel cy linder o f the veh i cle i n  t he fo rmof a p ul se.  A cy cle in whi ch th e pres su re ofhydra ul ic fluid  is supplied to the whe el cyl inder  is  lower th ana  cy cle of re sona nt vibrati ons  oc curri nga t a s uspe n si ons ystem  oft he vehicl e  d epe n d in g upon a ty p e ofthe v ehi c le.
Th e wh eel speed determi n ing circuit pr ovid e s  asig n al i nd icative of the  sp ee d of the w he el to the b raking c on d ition  deter mining  circui t .  A freque ncyhig her thana f re q uency o fre s onantvibr at ions o ccurri n g in a  suspension syst em of t he ve h icl e isre moved f r om t he signalindicativeof the  spe ed of  the wh ee l.
The  ch an ge in spee d  of the w heelis oneof  a f irs t para mete r repre sent in g a  differen c e  b e tw ee n  in stan t val ue s of  the spee d  of thewhe e l sampl ed  at a  given ti m e  intervalcyc lical l y  and a sec o nd p a ra m eterrepres enting  a diff e ren ce  betwee n i n s tant valu es of the fir st  par ameter s am pled  a t t he  given time int erval cy clically . The ch ang e  ins peed o fthe wheel ma y alt er n atively b e o ne of a fir stpar amet erthat is a first difference be twee n ins t ant  valu es of  t he speed of t he wheel sampled at agiven time inte r val cycl ica l ly  m inus a me anv alueof t hefirs t d iffe r e nces samp l ed  for  a
 systems.
It_is a_further object of the_invention to_provide_a brake_condition_determining device capable_of determining a_braking condition of a_vehicle accurately.
According to_one_aspect of the invention, there is provided an antiskid brake system for a vehicle._The_system includes:_(a)_a_wheel speed determining circuit determining_a speed of a wheel_of the_vehicle; (b) a parameter determining circuit determining a_parameter_reflecting on brake_torque applied to the wheel of the vehicle; (c)_a braking condition determining circuit comparing_a phase of_a_change_in speed of the_wheel determined by the wheel speed_determining circuit with a phase of_a change in parameter determined by the_parameter determining circuit to determine a_phase delay of the change_in speed_of the wheel and determining_a braking condition_based on_the phase delay;_and (d) an antiskid brake controlling_circuit performing antiskid_brake control based on the braking_condition_determined by the_braking_condition_determining circuit.
In_the preferred mode_of_the invention,_the_braking condition determining circuit increases the_parameter_in the form of a pulse and_determines the braking condition_the_change in speed of_the wheel as a function_of a step change in the_parameter.
The braking_condition determining_circuit determines the braking condition based on a fact that the_phase of the change in speed_of the wheel is_delayed from_the_phase of the_change_in parameter_determined by the parameter determining circuit as_a slip_ratio increases.
The parameter determined by the_parameter determining circuit is_a_pressure of hydraulic fluid supplied cyclically_to a wheel cylinder of the_vehicle in the form of_a_pulse._A cycle in which the_pressure of hydraulic fluid is supplied_to the wheel_cylinder is lower than a cycle of_resonant_vibrations occurring at a suspension system_of_the vehicle depending upon a type_of_the_vehicle.
The wheel speed determining circuit_provides a signal indicative of the_speed of the wheel to the braking condition determining_circuit. A frequency_higher than a frequency of_resonant_vibrations_occurring in a suspension system of the vehicle is removed_from the_signal indicative of_the speed of the wheel.
The change in speed of the_wheel is one of a first parameter_representing a difference between instant values of the speed of the_wheel sampled at a given time interval cyclically_and a second parameter representing a difference_between instant values of_the_first parameter sampled at the given time_interval_cyclically.
The_change_in speed of_the wheel may_alternatively be one_of a_first parameter that_is a_first difference between_instant_values of the speed of the wheel sampled at a given time interval cyclically minus a mean value_of the first differences sampled for_a