/Users/andrea/_magisterarbeit/korpus/clean/testkorpus/30/file16.html NN ----------------------------------------- : Back RB EMFMotion NP Feedbackfind NP . SENT HomeAccessoriesBatteriesBooksBrainStemConnectionsControllersDriversGiftsKitsLEGOLocomotionSensorsRelatedProducts NP BrainStem NP Moto NP 1 CD . SENT 0 CD Module NN 3 LS A DT Back NP EMF NP H NP BridgeBack NP EMF NP refers VVZ to TO using VVG the DT voltage NN generated VVN by IN a DT spinning JJ motor NN EMF NN to TO conclude VV the DT speed NN of IN the DT motor's JJ rotation NN . SENT This DT can MD be VB used VVN in IN motion NN control NN algorithms NNS to TO modulate VV the DT velocity NN or CC to TO compute VV the DT angular JJ distance NN the DT motor NN has VHZ traveled VVN over IN time NN . SENT This DT article NN attempts VVZ to TO describe VV this DT form NN of IN motion NN control NN feedback NN in IN more JJR detail NN . SENT Contents NNS . SENT IntroductionThe NP ProcessThe NP Moto NP 1 CD . SENT 0 CD and CC Back RB EMFBack NP EMF NP Measurement NN CircuitsLimitationsCredit NP and CC AttributionIntroductionTypically NP a DT motor NN takes VVZ power NN in IN the DT form NN of IN voltage NN and CC current JJ and CC converts VVZ the DT energy NN into IN mechanical JJ energy NN in IN the DT form NN of IN rotation NN . SENT With IN a DT generator NN , , this DT process NN is VBZ simply RB reversed VVN . SENT A DT generator NN takes VVZ mechanical JJ energy NN and CC converts VVZ it PP into IN both DT electrical JJ energy NN with IN a DT voltage NN and CC current JJ . SENT Most JJS motors NNS can MD be VB generators NNS by IN just RB spinning VVG the DT motor NN and CC looking VVG for IN a DT voltage NN current JJ on IN the DT motor NN windings NNS . SENT Note NN . SENT A DT very RB simple JJ demonstration NN of IN this DT is VBZ to TO wire VV two CD LEGO NP motors NNS together RB . SENT If IN you PP spin VV one PP , , the DT other JJ spins VVZ based VVN on IN the DT current NN you PP create VVP when WRB turning VVG the DT windings NNS of IN the DT first JJ motor NN . SENT If IN you PP have VHP them PP around RB , , give VV this DT a DT try NN , , it PP is VBZ fascinating JJ . SENT When WRB doing VVG Back RB EMF JJ measurements NNS for IN motion NN control NN , , this DT fact NN that IN a DT motor NN can MD also RB be VB a DT generator NN is VBZ exploited VVN . SENT The DT motor NN is VBZ run VVN almost RB continually RB as IN a DT motor NN with IN current NN being VBG supplied VVN to TO turn VV the DT windings NNS . SENT Occasionally RB , , and CC for IN a DT very RB short JJ period NN of IN time NN , , the DT process NN is VBZ reversed VVN . SENT The DT windings NNS are VBP allowed VVN to TO float VV and CC the DT inertia NN in IN the DT motor NN keeps VVZ it PP spinning JJ while IN a DT measurement NN of IN the DT voltage NN from IN the DT spinning JJ motor NN generator NN is VBZ taken VVN . SENT The DT voltage NN observed VVD when WRB the DT motor NN is VBZ spinning VVG is VBZ directly RB proportional JJ to TO the DT speed NN the DT motor NN is VBZ running VVG . SENT This DT fact NN can MD be VB used VVN to TO peek NN at IN the DT motor's JJ speed NN with IN no DT optical JJ encoders NNS or CC other JJ forms NNS of IN active JJ feedback NN . SENT ContentsThe NP ProcessReading NP the DT velocity NN from IN a DT motor NN using VVG Back NP EMF NP requires VVZ two CD alternating VVG steps NNS . SENT First RB , , the DT motor NN is VBZ run VVN for IN some DT period NN of IN time NN by IN providing VVG current JJ to TO the DT windings NNS . SENT This DT current NN can MD be VB supplied VVN as IN a DT constant JJ voltage NN or CC a DT PWM NP motor NN input NN to TO vary VV the DT speed NN . SENT The DT second JJ step NN is VBZ to TO remove VV the DT current JJ from IN the DT windings NNS and CC float VV them PP . SENT This DT means VVZ that IN there EX is VBZ no DT active JJ circuit NN between IN the DT windings NNS and CC any DT other JJ source NN sink NN . SENT This DT allows VVZ the DT inertia NN in IN the DT motor NN and CC mechanical JJ system NN to TO spin VV the DT motor NN long RB enough RB to TO measure VV the DT voltage NN produced VVN by IN the DT motor NN . SENT Typically RB these DT two CD steps NNS are VBP alternated VVN roughly RB 50 CD Hz NP or CC times NNS per IN second JJ . SENT The DT time NN required VVN for IN the DT motor NN to TO flip VV from IN a DT motor NN to TO a DT generator NN depends VVZ on IN the DT inherent JJ capacitance NN or CC stored VVD charge NN in IN the DT induction NN of IN the DT motor NN windings NNS . SENT This DT time NN is VBZ typically RB in IN the DT order NN of IN a DT millisecond NN or CC two CD , , depending VVG on IN the DT conditions NNS . SENT Watching VVG the DT process NN on IN a DT scope NN can MD give VV you PP some DT idea NN of IN the DT timing NN . SENT Below IN we PP walk VVP through IN some DT simulated JJ scope NN pictures NNS to TO show VV these DT various JJ steps NNS and CC introduce VV some DT terminology NN used VVN in IN the DT BrainStem NP Moto NP 1 CD . SENT 0 CD Application NN to TO control VV a DT motor NN using VVG Back NP EMF NP . SENT Above IN we PP see VVP how WRB a DT scope NN might MD look VV when WRB running VVG a DT motor NN at IN 1 CD 4 CD speed NN . SENT Notice VV how WRB the DT Back NP EMF NP rises VVZ up RP to TO roughly RB 1 CD 4 CD of IN the DT PWM NP maximum NN voltage NN and CC stabilizes VVZ . SENT If IN the DT Back JJ EMF NP measurement NN gap NN is VBZ too RB long RB , , the DT motor NN will MD begin VV to TO slow VV down RP and CC the DT feedback NN will MD drop VV accordingly RB . SENT Next RB , , we PP see VVP what WP the DT scope NN might MD look VV like IN when WRB running VVG the DT motor NN at IN 3 CD 4 CD speed NN . SENT Notice NN how WRB most JJS everything NN remains VVZ the DT same JJ but CC now RB the DT stable JJ Back NP EMF NP signal NN is VBZ roughly RB 3 CD 4 CD of IN the DT maximum JJ motor NN winding VVG voltage NN . SENT Finally RB , , we PP see VVP what WP the DT 3 CD 4 CD speed NN case NN might MD look VV like IN when WRB the DT motor NN is VBZ under IN load NN . SENT Since IN the DT motor NN has VHZ a DT great JJ deal NN of IN current JJ developing VVG a DT large JJ induction NN in IN the DT windings NNS when WRB it PP is VBZ under IN load NN , , the DT inductive JJ spike NN is VBZ bigger JJR and CC the DT stable JJ Back NP EMF NP region NN takes VVZ longer RB to TO achieve VV as IN this DT larger JJR induction NN must MD be VB dumped VVN from IN the DT windings NNS first JJ before IN the DT Back JJ EMF NP region NN stabilizes VVZ . SENT Proper JJ tuning VVG of IN the DT latency NN before IN taking VVG the DT measurement NN is VBZ important JJ to TO minimize VV the DT measurement NN gap NN while IN allowing VVG enough JJ time NN for IN stable JJ Back NP EMF NP measurement NN . SENT ContentsThe NP Moto NP 1 CD . SENT 0 CD and CC Back RB EMFThe NP BrainStem NP Moto NP 1 CD . SENT 0 CD module NN is VBZ a DT very RB flexible JJ motion NN control NN board NN . SENT It PP has VHZ the DT built VVN in IN parameters NNS to TO handle VV timing NN required VVN for IN Back NP EMF NP feedback NN control NN using VVG a DT PID JJ loop NN to TO manage VV the DT motor NN outputs NNS based VVN on IN the DT velocity NN feedback NN provided VVN by IN the DT Back JJ EMF NP measurement NN . SENT Below RB is VBZ a DT diagram NN of IN the DT flow NN of IN information NN in IN the DT closed JJ loop NN control NN when WRB using VVG the DT Moto NP 1 CD . SENT 0 CD module NN in IN A DT D NP velocity NN mode NN Back NP EMF NP mode NN . SENT This DT loop NN repeats VVZ at IN an DT adjustable JJ frequency NN with IN typical JJ values NNS ranging VVG from IN 10 CD 200 CD Hz NP . SENT to TO effect VV speed NN control NN without IN encoders NNS . SENT The DT settings NNS the DT orange NN inputs NNS on IN the DT left NN are VBP all RB adjustable JJ through IN a DT simple JJ User NP Interface NP that WDT runs VVZ on IN a DT variety NN of IN platforms NNS . SENT Here RB is VBZ the DT interface NN used VVN to TO adjust VV these DT settings NNS . SENT ContentsBack NP EMF NP Measurement NN CircuitsThe NP Back NP EMF NP measurement NN circuit NN can MD be VB a DT bit NN challenging VVG . SENT The DT circuit NN needs VVZ to TO handle VV the DT possibly RB large JJ voltages NNS of IN the DT motor NN and CC convert VV them PP into IN a DT range NN that IN the DT A NP D NP inputs NNS of IN a DT microcontroller NN can MD handle VV . SENT In IN addition NN , , the DT windings NNS of IN the DT motor NN invert NN when WRB the DT motor NN direction NN changes NNS so IN the DT circuit NN needs VVZ to TO both CC adjust VV the DT voltage NN range NN and CC create VV an DT input NN offset VVN so RB that IN the DT neutral JJ not RB spinning JJ voltage NN output NN of IN the DT measurement NN circuit NN centers NNS around IN a DT known VVN value NN . SENT If IN you PP are VBP only RB running VVG the DT motor NN in IN one CD direction NN , , this DT circuit NN can MD be VB as RB simple JJ as IN a DT resistor NN ladder NN to TO scale VV the DT voltage NN to TO the DT A NP D NP range NN . SENT If IN the DT motor NN is VBZ running VVG bi NP directionally RB , , a DT more RBR sophisticated JJ circuit NN is VBZ required VVN . SENT The DT Acroname NP 3 CD A NP Back NP EMF NP H NP Bridge NP uses VVZ a DT two CD stage NN operational JJ amplifier NN to TO manage VV this DT voltage NN scaling NN and CC offset VVN . SENT This DT circuit NN also RB must MD have VH the DT brake NN turned VVD ON RP for IN floating VVG the DT windings NNS during IN the DT Back JJ EMF NP measurement NN gap NN due JJ to TO the DT characteristics NNS of IN the DT LMD NP 18200 CD H NP Bridge NP employed VVN for IN the DT motor NN outputs NNS on IN the DT 3 CD A NP Back NP EMF NP H NP Bridge NP . SENT This DT activation NN of IN the DT brake NN circuit NN is VBZ referred VVN to TO as IN auto NN braking VVG in IN the DT Moto NP 1 CD . SENT 0 CD module NN . SENT There EX are VBP probably RB as IN many JJ ways NNS to TO measure VV the DT voltage NN in IN a DT Back JJ EMF NP circuit NN as IN there EX are VBP potential JJ motor NN , , direction NN , , and CC voltage NN combinations NNS . SENT The DT key NN is VBZ to TO ensure VV that IN the DT measurement NN is VBZ passive JJ so IN it PP doesn't VVD affect VV the DT motor NN and CC that IN it PP is VBZ fast RB so RB that IN the DT motor NN can MD spent VVD most JJS of IN the DT time NN running NN . SENT ContentsLimitationsBack NP EMF NP velocity NN measurement NN is VBZ novel JJ and CC great JJ if IN you PP don't VVD have VH an DT encoder NN on IN your PP$ motor NN . SENT Good JJ quadrature NN encoders NNS like IN those DT used VVN in IN the DT Garcia NP robot NN will MD typically RB out RB perform VV the DT Back JJ EMF NP measurement NN method NN described VVD here RB . SENT In IN addition NN , , encoders NNS can MD give VV absolute JJ position NN information NN whereas IN Back NP EMF NP can MD only RB report VV velocity NN . SENT Position NN must MD be VB computed VVN through IN integrating VVG the DT velocity NN over IN time NN which WDT has VHZ significant JJ limitations NNS . SENT One CD other JJ limitation NN of IN Back NP EMF NP velocity NN control NN is VBZ that IN it PP effectively RB reduces VVZ the DT maximal JJ duty NN cycle NN that WDT can MD be VB obtained VVN from IN the DT motor NN as IN it PP requires VVZ the DT motor NN to TO be VB turned VVN off RP at IN times NNS during IN the DT operation NN to TO facilitate VV the DT measurements NNS . SENT ContentsCredit NP and CC AttributionBack NP EMF NP motion NN control NN has VHZ been VBN around RP for IN decades NNS finding VVG use NN in IN model NN trains NNS , , audio JJ tape NN transport NN mechanisms NNS , , and CC other JJ special JJ purpose NN uses NNS . SENT Acroname NP first RB learned VVD of IN this DT approach NN to TO speed VV control NN while IN talking VVG with IN Randy NP Sargent NP about RB work VV he PP and CC Bill NP Bailey NP were VBD doing VVG with IN velocity NN measurement NN for IN robotics NNS . SENT Thanks NNS to TO Randy NP and CC Bill NP for IN sharing VVG this DT information NN with IN the DT robotics NNS community NN . SENT aboutRoboticsarticlesbrainstemcontactdownloadsexamplesforumsgarciagalleryhow NN tohomeideasstandardsindexinformationmailing NN listPPRKRelated JJ LinksAcroname NP Products NPS . SENT 3 LS A DT Back NP EMF NP H NP BridgeNASA NP CMU NP Summer NPS Robot NN Course NP featuring VVG the DT Acroname NN powered VVN TrikebotAcroname NP Products NPS . SENT BrainStem NP Moto NP 1 CD . SENT 0 CD ModulePathhome NN . SENT robotics NNS . SENT info NN . SENT articles NNS . SENT back RB emfvoice NN . SENT 720 CD 564 CD 0373 CD , , email NP . SENT sales NNS acroname JJ . SENT com NN , , address NN . SENT 4894 CD Sterling NN Dr NN . SENT , , Boulder NP CO NP , , 80301 CD 2350 CD , , privacy NN Copyright NP 1994 CD 2005 CD Acroname NP , , Inc NP . SENT , , Boulder NP , , Colorado NP . SENT All DT rights NNS reserved VVD . SENT