CA2185523A1 - Blind spot detector - Google Patents
Blind spot detectorInfo
- Publication number
- CA2185523A1 CA2185523A1 CA002185523A CA2185523A CA2185523A1 CA 2185523 A1 CA2185523 A1 CA 2185523A1 CA 002185523 A CA002185523 A CA 002185523A CA 2185523 A CA2185523 A CA 2185523A CA 2185523 A1 CA2185523 A1 CA 2185523A1
- Authority
- CA
- Canada
- Prior art keywords
- threshold
- vehicle
- view
- field
- blind spot
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R1/00—Optical viewing arrangements; Real-time viewing arrangements for drivers or passengers using optical image capturing systems, e.g. cameras or video systems specially adapted for use in or on vehicles
- B60R1/12—Mirror assemblies combined with other articles, e.g. clocks
Abstract
A device for detecting the presence of an object in the blind spot of a vehicle comprises a passive infrared sensor mountable on the vehicle so as to have its field of view directed toward the blind spot. The infrared sensor generates a signal in response to a heat-emitting object moving about its field of view. A bandpass filter passes signals having a frequency within a predetermined band characteristic of moving vehicles. An indicator indicates the presence of an object upon detection of a signal in the predetermined band.
Description
W095/25322 2 1 8 ~ ~ 2 ~ Pcr1c~95l00134 3~3 ~D SPOT D.3TECTO~ I
This invention relates to a blind spot detector ~or use in moving vehicles, particularly, but not exclu8ively! A71t~ R. It can also be applied to other r7 ~rr~;rS7~irnF~ for example, detecting t~e presence of children near a school bus It has been a long rerorni 7ecl problem that the driver of an automobile has a blind spot on either side of the vehicle to the rear of the driverls prf:;t;nn in which overtaking vehicles are not visible either in the rear view mirror or the side mirrors. This can lead to pot~nti;7lly ~7A~y~J P situations when the driver changes lanes, part;r~1lArly in dense traffic. Quite often two cars may proceed in pArAl~ with the trA;l;n~ car ~ ininrj i~ the blind spot of the leading car for some crnFir7~ors7hle period of time. If the leading driver changes lane~ without properly making a visual check of his blind spots, a crlliP;on can result.
In the prior art, various A7 t~ ~3 have been made to provide d~ot~rt;on devices for ~7~t~rt;n~ the rrl~C~onre of objects in the blind spot. An example of one such device is described in ~S Patent No. 5,122,796. This patent ~7.;ACI~7s~P a vehicle ~7~t~o~tr~r which employs an electro-optical emitter for sending a light beam to a trr7;1;
vehicle and a receiver for picking up the light r~flect-~fl from the vehicle. This device is typical of the prior art in that it requires an active tr;~nF~i tti n,q element to direct a light beam to the vehicle to be ~7~t~rt~1. US
Patent No. 4,260,980 discloses a similar alla-ly employing 111trs~Frn;c waves. US Pate~t No. 3,697,985 discloses a system emp~oying Doppler radar systems.
The systems ~7~Prr;hl~fl in the above patent have in common the fact that they are active systems; that is they require the use of a trAnPn~i tt~r to send some sort of signal which is r~fl~ct~fl off the tr~;ling vehicle and ll WO 95/~5~22 2 18 5 ~ 2 ~ PCT/CA95100~34 ~ - 2 -picked up by a detector on the leading vehicle Such active devices are relatively expen6ive to make and are very sen6itive to rnn~min~t;nn by dirt and the like thrown up from the road Such active devices have a 5 significant power consumption and need to be hard wired into the vehicle electrical system IJS Patent No. 3,681,750 discloses a pasDive system which relies on the detector picking up ultrasonic ~m;s~inn~ from the trailing vehicle. Such a device 10 reguires a frusto-conical horn to pick up the llltrnSnn;r signals from the appropriate direction, but even with such a horn the system has poor pn~;tinn;ll disrr;m;n~tinn. ~Urth~ - e, the horn has a si~n;f;-Ant size and thus impairs the aerodynamic and aesthetic 15 g,lA7; t~ of the vehicle .
US patent no. 5,249,128 A;~rlo~ the use of a passive infrared A~ter~ tn~ for range sensing. ~here is no teArh;n~ of blind spot A~t~ctinn or how to discriminate vehicle signals from fal6e signalæ q~n~r~t~d, for 20 example, by the road surface.
An obj ect of the invention is to provide a small, low cost blind 6pot detector that can }~e conveniently to a vehicle without the need to hard wire it into the vehicle ~- ~tr; CAl system According to the pre6ent invention there is provided a device for detecting the presence of an object in the blind spot of a moving vehicle, ,- ~ ~;nq a pas6ive infrared motion 6ensor ~hle on the vehicle so as to have its field of view directed toward the blind spot, said infrared sensor q~nor7t;nq a signal in LeD~ D~ to a heat-emitting object moving about its field of view; a hAnArA~s filter for passing signal6 having a rLe~ue~ey ';
within a pr~A~t~rm;noA band rh~r~ct~ tic of moving vehicles; and an ;nA;rAtnr for ;n,l;c~r;nq the pre6ence of wo gs/~ 2 1 8 ~ S 2 3 PCT~C~95~00134 an object upon lPtect; nn of a signal in said prP-lPtP~;nP~ band The dPt~qctor ~rrnr~l;n~ to the invention is - responfiive to the heat gPnPrAted by the engine of the 5 trailing vehicle. ~ simple low cost passive infrared motion sensor, developed for the home security market, is preferred. A suitable fiensor i5 dual element lithium r~nt~lAte crystal with a low noise EET transistor mounted on a ~ e and ~nrlnF~ in a metal housing with a 10 silicon window having part number ~iEIMANN I~I 958.
Such a sensor has a Fresnel lenfi with well defined lobefi . The lithium tAntAl Ate crystals discharge when infrared r~ t; nn falls on them. ~he~ an object moves acrosfi the field of view of the ~lPtPCtn-, it moves across 15 the ~ oll~e lobea so as to ~pn~ tp an output signal. If the two objects are stationary relative to each other, no output signal is produced.
The vehicle carrying the sensor is of course moving along the road. If the road surface were at a uniform 20 temperature, it would be produce no output signal. In rr~ct; rP, due to differential heating the road surface does produce an output signal at the d~t~ctnr that can be as large as that caused by the trailing vehicle. It has been found, however, that differential heating causes a 25 ~ict;nrtly aifferent signature from a moving vehicle ~:Pn~rAl 7y road signals r--;~---; ly lie in the fre~auency range below 0 51Iz. These signals are mostly P~r~ Pd by the b~n~lr~ filter.
When two vehicles are traveling in parallel along 30 the highway, the random motion of the trailing vehicle across the field of view of the ~lPtPctor will result in the ~lPt~rt; c n of the trailing vehicle even if the two vehicles are moving along the road at the same speed Such a ~7PtPctnr can be made at ~l ~y low cost 35 due in part to the fact that motion ~ensors are mabb w095~s322 2~8~52~ PCJ/C~9SJ00134 _ 4 _ !
!
produced for the security market. The sensors are rugged and consume low power since the control circuitry can be made using CMOS devices. Using lithium batteries, the battery life is P~ortP~a to exceed si~ months rnnt;mlcnls 5 use under average nr~r~tinr~ conditions. It is envisaged that the device will be ;itt~rhoa, preferably adhesively, to the side view mirrors of a vehicle and left pP~-nPntly on. In the idle state, the current drair. will be very small indeed When a vehicle i8 detected, a light-emitting diode will be ;11 n2ted, and this will be visible through the side ~indow from the driver~s pof~;t;nn Unlike most infrared sensing devices working in the reguired t ~ tllre range, the inventive device does not 15 reguire a chopper, cryogenic cooling unit, or ~o~-~n;
lenses. Only a very si~ple s;~n~;n~ Cnna~it;nn;n~ circuit is reguired.
The Fresnel lenses are preferably made of polyethylene.
An important preferred aspect of the irvention is the ability to adapt to rh~n~; n~ ~ t.Pnrnl r,~; r~l cnnla;t;nn~. For example, in periods of heavy rain, car si ~ eS are reduced due to the cooling effect of rain.
Fortunately, the road signature is also reduced due to the fact that the thermal mass of the rain evens out the t- L~ e v~r;Pt;nn~ in the road surface. In the preferred ~ the invention exploits this effect to adaptively adjust the threshold at which a vehicle is considered present lalorona;n r on the nu~ber of noise events ~lotectecl below the present threshold in a pr~ torm;no~l period of time For examplê, if a large number of noise events are flotectod, the threshold is raised . If only a f ew are detected the threshold is lowered This makes the flotertnr more sensitive, but only w0 9~22 2 1 8 ~ ~ 2 3 PCT/C~95/00134 when there is relatively little road noise, for e~ample during periods of heavy rain.
The invention also provides a method of detecting the presence of an object device for ClPtPf~;n~ the presence of an object in the blind Epot of a moving vehicle, characterized in that it co~,prises directing a passive infrared sensor toward the blind spot, said infrared sensor gPnPrZ~t;n~ a signal in response to a heat-emitting object moving about its field of view;
passing signals through a ~ filter for having a ~rPq-lfnry within a prp~lptp~;np~ band rh~r~ftPr; ~tic of moving vehicles; and ;n~ qting the presence of an object upon ~lPtert;r-n of a signal in said rrPtlPtPrm;nP~ band.
The invention will now be ~lP~hPtl in n~ore detail, by way of example only, with reference to the -'3f- ~ ying drawings, in which~
Figure 1 is a plan view showing three vehicles moving along adj acent lanes in a highway;
Figure 2 i8 a rear view of the vehicles shown in 2 0 Figure 1;
Figure 3 ifi a ~ ; c view showing the angular ~o--s~ of the infrared ~l~PtP~ tnr;
Figure 4a is a circuit diagram of the signal conditioning circuit;
Figures 4b to 4f show the signal at various stages in the signal cnn~l;t;on;n~ circuit; and Figure S shows the voltage regulator for the conditioning circuit;
Figure 6 shows the system field o~ view in the direction of travel in more detail;
Figure 7 shows the ~ ;Pr frequency response of a second . ';
i WO 95/25322 2 18 ~ ~ 2 3 PC'r~CA9~/0013~
Figure 8 is a system block diagram of the second ' o~
Figure 9 is a top level flow chart describing the op~rA~ t; nn of the second r--hotA~
Figure 10 is a noise ~ flow chart for the second `~
Figure 11 is a flow chart showing the car detection ~rati nn of the second ~
Figure 12 is a flow chart tA~ rih;n~ the threshold setting operation;
Figure 13 shows the lens cnnf;~lr~At;nn in elevational view; and Figure 14 shows the lens cnnf;~ Ati~n in plan view;
and Figure 15 is a ~ t~ d circuit diagram of the second: A ' ~ ~
Referring now to Figure 1, vehicles 7, 8 and 9 are shown mo~ring along adjacent lanes of a highway, with vehicles 8 and 9 in the blind spot on either side of 20 vehicle 7.
Vehicle 7 haæ side view mirrors 1, 2 with respective passive infrared d~tectnr~ la, 2a mounted thereon. I~ach infrared d~tect~r ha8 a hr'r;-'''ntAl field of view Q. The field of view of n~otectnr la has respective outer and 25 inner edges 3, 4, whereas the detector 2a has a field of view ~ with respect to inner and outer edges 5, 6. These edge8 are chosen to outline the vehicle blind spot Figure 2 shows the same layout from the rear, and thus shows the field of view ~ of the detectors la, 2a in 30 the vertical plane. AS will be apparent from Figures 1 and 2, the ~ tPntnrs la, 2a have a generally ' ~d directed conical field of view covering the vehicle blind WO 95125322 2 1 8 ~ S 2 3 PCr/CA9510013~ ~
8pOt. Vehicles outside this conical field of view are not normally detected.
The ~lPtertnrs la, 2a are normally mounted on the side view mirrors with an adhesive. The detectors include 5 red light-~m;t~;n~ diodes that are visible from the driver's position and that ;ll n~te when a moving heat-emitting source is detected in the field of view ~, ~ of the ~lPtectnrs la, 2a. This alerts the driver to the presence of a vehicle in the blind spot, although before 10 switching lanes the driver should still make a guick visual check by glancing over his shoulder The passive infrared motion ~letect~rs employed in the device have lenses that give an angular response as shown in Figure 3, that is they have a series of radial 15 lobes 10 in the circumf erential direction . This means that the detector has its greatest response along radii a, c, with a minimum along radius b between the radii a and c. The crystals are ~ P~7 80 that a st~t;nn;~ry object pr~7llr~ a ~ero ~utput signal.
As an object moves across the field of view ~rom a to c, the r~7;~inn received by the crystals within the t~ctnr passes through a minimum at b maYimUm at c. mis creates an output signal from the crystals, which in the invention is used to detect the presence of an object.
me relative ~ of the obj ect and detector is caused in part the random motion of the trailing vehicle across the f ield of view of the detector.
This output signal is conditioned by the Cnn~7;~;nn;n~ circuit 5hown in Figure 4a FPfPrrins now to Figure 4, the signal conditioning circuit comprises a clPte-rnr 20, a filter _7;f;Pr 30, an . lif;Gr 40, a ~ _ !nr 50 and a monostable circuit ~0. The cl~otPctor ;nnlll~7P,c: the passive infrared sen50r 21 which is 8llrr~;
with steady voltage V2 provided by the voltage re~ nr shown in Figure 5 . The voltage V2 is s~lppl; P~ through WO 95f25322 2 1 ~ 5 S 2 3 pCTlC~.9510013J, I
series resistors Rl, R2. These resistors in conjunction with the capacitor C, provide a ripple-_ree voltage supply to the sensor 21 The output voltage of the detector 20, which is in 5 the microvolt range, i8 shown in Figure 4a When a target is ~l~t~ct~l, the spike 22 occurs.
The filter/ _l;f;Pr 30 ~r;~ two np~r~t;o ~mrl;f;~rF: 31, 32, which form a band pass filter that matches the output L- e.~ y response of the infrared 10 sensor and rl;~rr;m;n~tes vehicle response from road noise. The circuit also provides a s;rJn;fir~nt amount of gain, providing an output signal in the millivolt range as shown in Figure 4b The output of circuit 30 is applied to ~ r 15 circuit 40, which comprises opPri~t;nn~l l;fi"r 41 This provides further l;f;r~t;rn and also DC filtering through ~r~r; tnr C8 . The output voltage is offset with a voltage provided by resistor network Rll and R12 The output of _ l; f; ~r circuit 40, which is shown in Figure 20 4c, is a circuit in the millivolt range.
The output _l;f;or 40 is applied to co~parator 50, ~- ~;n~ r~rat;onzll, _l;f;-~r~ 51, 52. ~'~ _ r,r 50 is a ~q~r;~ n-making circuit that defines upper and lower bounds of thè input signa~ (Figure 4d). These are set 25 with variable resistor R15, which therefore sets the sensitivity of the circuit. When the - - ~nr 50 registers the target, due to the signal falling outside the upper and lower bounds, as shown in Figure 4d, the r produces a _alling edge voltage signal of 30 small ~ r~tirn at its output. This filter signal is in the volt range and is applied to _ ~hle m~ultivibrator 60, which is a falling edge triggered circuit used to ~ -prolong the duration of the output signal of the c _ rr me output signal, shown in figure 4e, is an 35 output pulse whose ~lllr~tirn is set by resistor R20 and WO 95/2S322 pCTlC~9~/0013~1 ~ ` 2185S23 9.
capacitor Cll The ontput o~ monostable 60 is a voltage Gignal in the volt range, which is used to drive LED 62 that acts as a visual ;nA;c~trr to the driver of the presence of a target.
The conditioning circuit shown in Figure 4 is implemented in CMOS and therefore has very low power cv~u,~ion. This i8 also helped by the fact that it i8 purely a passive, non-r~A;~tin~ device The detector normally operates in the 6 to 14 micron 10 long wave infrared ~ t;nn and is ~Pn~r~l ly responsive to the heat emitted by the engines of moving vehicles. It has bee~ found that the device responds well to vehicle engines with minimal false ;nA;r~;r,nc While the device has been desig~ed particularly with 15 ~ ' 1P~ in mind, it can be applied to other applications, for example aircraft ~l;n~t;oncl where there is a need to detect the yL~5~:uc~ of heat-P"~;tt;
targets The d~tertnrs are ~tt~rh~d to the side mirrors by a 20 durable automotive adhesive. Since they are self-rnn~;n~l and battery QpGr~tPd, no wiring or electrical rnnnPct;rn to the vehicle PlPr~ric~l system is required.
This means they can be distrih~ltPd as low-cost accessories for easy non-invasive ~ ;r~t;nn by the 25 vehicle owner. ~11 he has to do is stick the device in the appropriate poc;~;nn where it is visible from the driver~s pos;r;on through the vehicle window By using a lithium battery, rr,nt;mlnllc opPr~t;~r,n in excess of six months can be achieved. The device is not 30 designed to be switched off. When no target is detected, the current con~, , ; r,n is nominal .
If desired, an ~AA;t;nn~l LED having a different color, such as a amber LED, can be provided to give early warning of a low battery condition.
WO 95/25322 2 1 8 ;~ PCT/CA9~10013.
The optics of the passive ;nfr~rPcl detector will now be discussed in more detail with reference to Figures 6, 13 and 14 This infrared detector could be used in either the first: -' discussed above or in the second 5 ~mhoA1 - to be described below me infrared A~t~rtor only responds to changes in observed t~ _ t e across its field of view. Thus, it is only pOSS;hl.Q for the system to detect objects which cross the field of view. Objects colaing straight towards 10 the 6ensor produce little or now response. For this reason the FoV is angled out from the vehicle direction by about 20 +5~ so that vehicles entering the blind spot actual are f orced to cross the FoV.
Secondly the optimum focal length has been found to 15 be about 25 mm. Shorter focal lengths give a larger FoV
~field of view), but produce a lower effective car frequency ~ign~tl~re. miS makes ~r~r~t;nn of car and road ~ S A;~'f;rl~1t or ~ -_ hl-o, Longer focal lengths have several disadvantages:
a) me llaL~ L spot beam requires better alignment .
b) The beam may not cover the hot spot on the car.
c) More lens ~ are required to give the reguired hnr~7rmt~7 coverage.
d~ A larger physical size of the unit is required to house the larger optics.
The optics is ;3r~ to give the FoV shown in Pigure 6. The ~1;5 must be fairly precise to get this FoV Three angles are involved which can be termed 30 yaw, pitch, and roll. Yaw A~t~rm;nF~ the Tlnr;7-~nt~1 FoV
and is least critical of the three It is est~hl i ch~A by the user simply by aligning a reference line towards the rear of the car. Tnl ~r~nce is + 5 . The roll angle Al~t~rmin-~: the extent to which the FoV extends to the , w09s~22 2 1 8 ~ ~2 3 PCI/C~ 95/01)13~ i ~' - 11 -side of the car. Ideally the FoV of view would be limited to the adjacent lane (3.5 m) In fact, it is chosen to extend slightly beyond this so that sufficient signature is picked up f rom cars in the blind spot . me result is 5 that ocr~qinn~lly there will be triggering from cars one lane over Roll angle should be 15 ~ 2. Pitch i8 the most r~r;t;C~l angle and ~7PtPrm;nPq h~q1c~11y how far the FoV extends behind the car . If it is too high ob~ ects very far away (b7~ 7;n~q, setting sun etc.) will give 10 false triggers. If it is too low the vehicle will not be ~7PtectPfl until it is well into the blind spot. Pitch angle is set to 1.5 i 1.
Pitch and roll angles are set by the user placing a circular level on a surface of the device which when 15 level is set to give the correct roll and pitch angles.
me device la, 2a uses eight lens elementa (i. . .viii) to give h~r; ~nt~l coverage o~ about 60, as shown in Figure 13 The second: ' ' , as shown i~ Figure 8, has a 20 passive infrared detector 70, a hanflr~qq ,l;f;Pr ?1, a detector circuit 72, an LED flasher 73, and a noise event counter 74.
The: l;f;Pr 71 has a specific b~nflr;-qq l~h~rPrtPr;qtic to provide near optim 1 dis~r;m;n~t;on 25 between vehicle and road ~ackground signatures. It has been detern7ined P~pPr; lly that with proper optical alignment, the electronic siy~Lu eb of vehicles lie rr;r-r;7y in the region above 0.5 Erz~ while the electronic s;~n~t~res of the road background lie 30 primarily below O.s ~z In bright sunshine because of differential heating o~ the road surface, the ba~ylvu~d signature can easily be as large as that of a vehicle so that it is vital that these siy~ Lu~ es be filtered out. The device has in fact 35 three filters with high pass cut offs at 0 08, 0 7 and -wog~322 2 1 8 5 ~ 2 3 pCI~/CA95J00i3~ `
O . 7 ~Iz, respectively. As well a second order low pass filter cut off at 4.2 ~z is used to limit high fre~auency noise. The filter response is shown in Fiy-ure 7.
The ~; ~n~tllre received from cars i8 strongly 5 r1~r~n~lPnt on weather cnn~;tinn~. Particularly in medium to heavy rain, the &ignature from vehicles can be .' ;r~qlly reduced. Fortunately, it is possihle for the device to ~ t~rm;n~ when this ~nni;t;~n eYists by nitoring h~ J, ,u i noise as the h~rk~rolln~l sig~ature ~0 is reduced as well during rain - i . e . the road tends to be of re uni~orm t ~ I._LaLUL~:: due to the high thermal - mass of the rain water.
The blind spot elPte~ctnr takes advanLcly~= of this e__ect by collnt;n~ noise values over a given threshold in 15 the noise event counter 74. ~fter a l~L~ ;n~ period, a threshold is chosen that depends on the number of noise counts over the roise threshold. Eligher counts give higher thresholds The period is ~t~n;nP~l by rmlnt;ng the numher of samples below the lowest possible car 20 cl~tP~-t;~n threshold. Thus, the St~t;~t;r~ are not upset by the presence or absence of vehicles in the blind spot.
Sper;f;r~lly, with the ,,l;f;~r gain set to 66 dB
the noise threshold used is 30 mv. The po~3;hl~ cæ
detection thresholds are 50 mv, 100 mv, 150 mv and 200 25 mv me count is done to a m~ximum of 32 events below 50 mv Each event is sampled for about 800 msec so that a new threshold is chosen about every 25 sec if no events over 50 mv occur. The threshold for the next 25 sec interval is set based on the numher of events between 30 30 and 50 mv as follows:
less than 3 events m = 50 mv between 3 and 7 events m = loo mv between ~ and 20 events m = 150 mv more than 20 events Th = 200 mv WO 95125322 2 1 8 5 S 2 3 PCT~CA95/00134 A time out check is alGO ;~r7 ~-1 to prevent the system locking up due to constant noise or car signatures over 50 mv. After one minute of this condition, the threshold is set to 200 mv.
The detailed ortPr~t;nn of the second ~ - , which is mieLu~LuCeSSOr based, is illustrated in Figures 9 to 12.
The detailed circuitry for the second: ' ' is shown in Figure 15 The circuit is controlled by microprocessor 100, which is a Motorola 6805 A signal from passive infrared ~9Ftecto~ 101 is fed through operational ~ ~ 1 i f i ~~~ 102, 103, which also act as b~n-lr~s filters. The output of; _l;fi~r 103 is fed to op~rFIt;nn~l: 1ifi-~rS 104, 105, which acts as ~ , ~ o~. Switches 106 provide the threshold adj__ circuitry.
The invention also has other ~rrlir~ti,~nc, such as school bus child detectors. An inte~r~t~d Multiple unit could cover a long vehicle, such as tractor trailers.
With the current invention, pickup of shadows from overpasses call occur, in particular on sunny days. This is because of the cooler road t ~ ~ under the underpass. It is possible to -~ e for this hy having two d~tPctnrs with one pointing straight down at the road to establish the ~le~ell~e of a shadow. This information can then be, n~ with the data from the car detection sensor to reduce the ~tert; nn of shadows .
The current iIlvention takes advantage of the relative motion of the two vehicles to produce the ~l~tertion signal Normally in most driving s;tll~t;nn~:
this is s~lf~in;~nt to give a very high prnh~hil;ty of detection. }Iowever it is conceivable, ~pe~;A~ly under heavy rain when car s; ~n~tllres are reduced, that relative motion may not be enough to trigger the device This 35 problem can be uveLc by me~h~nir~lly vibrating the WO 95125322 2 1 8 ~ S 2 3 PCT/C~95/00l34 mirror, le~6 or 5ensor to provide a scanning motion of the car ~ig ~eOre ac~o~ ehe iececc~r.
~'
This invention relates to a blind spot detector ~or use in moving vehicles, particularly, but not exclu8ively! A71t~ R. It can also be applied to other r7 ~rr~;rS7~irnF~ for example, detecting t~e presence of children near a school bus It has been a long rerorni 7ecl problem that the driver of an automobile has a blind spot on either side of the vehicle to the rear of the driverls prf:;t;nn in which overtaking vehicles are not visible either in the rear view mirror or the side mirrors. This can lead to pot~nti;7lly ~7A~y~J P situations when the driver changes lanes, part;r~1lArly in dense traffic. Quite often two cars may proceed in pArAl~ with the trA;l;n~ car ~ ininrj i~ the blind spot of the leading car for some crnFir7~ors7hle period of time. If the leading driver changes lane~ without properly making a visual check of his blind spots, a crlliP;on can result.
In the prior art, various A7 t~ ~3 have been made to provide d~ot~rt;on devices for ~7~t~rt;n~ the rrl~C~onre of objects in the blind spot. An example of one such device is described in ~S Patent No. 5,122,796. This patent ~7.;ACI~7s~P a vehicle ~7~t~o~tr~r which employs an electro-optical emitter for sending a light beam to a trr7;1;
vehicle and a receiver for picking up the light r~flect-~fl from the vehicle. This device is typical of the prior art in that it requires an active tr;~nF~i tti n,q element to direct a light beam to the vehicle to be ~7~t~rt~1. US
Patent No. 4,260,980 discloses a similar alla-ly employing 111trs~Frn;c waves. US Pate~t No. 3,697,985 discloses a system emp~oying Doppler radar systems.
The systems ~7~Prr;hl~fl in the above patent have in common the fact that they are active systems; that is they require the use of a trAnPn~i tt~r to send some sort of signal which is r~fl~ct~fl off the tr~;ling vehicle and ll WO 95/~5~22 2 18 5 ~ 2 ~ PCT/CA95100~34 ~ - 2 -picked up by a detector on the leading vehicle Such active devices are relatively expen6ive to make and are very sen6itive to rnn~min~t;nn by dirt and the like thrown up from the road Such active devices have a 5 significant power consumption and need to be hard wired into the vehicle electrical system IJS Patent No. 3,681,750 discloses a pasDive system which relies on the detector picking up ultrasonic ~m;s~inn~ from the trailing vehicle. Such a device 10 reguires a frusto-conical horn to pick up the llltrnSnn;r signals from the appropriate direction, but even with such a horn the system has poor pn~;tinn;ll disrr;m;n~tinn. ~Urth~ - e, the horn has a si~n;f;-Ant size and thus impairs the aerodynamic and aesthetic 15 g,lA7; t~ of the vehicle .
US patent no. 5,249,128 A;~rlo~ the use of a passive infrared A~ter~ tn~ for range sensing. ~here is no teArh;n~ of blind spot A~t~ctinn or how to discriminate vehicle signals from fal6e signalæ q~n~r~t~d, for 20 example, by the road surface.
An obj ect of the invention is to provide a small, low cost blind 6pot detector that can }~e conveniently to a vehicle without the need to hard wire it into the vehicle ~- ~tr; CAl system According to the pre6ent invention there is provided a device for detecting the presence of an object in the blind spot of a moving vehicle, ,- ~ ~;nq a pas6ive infrared motion 6ensor ~hle on the vehicle so as to have its field of view directed toward the blind spot, said infrared sensor q~nor7t;nq a signal in LeD~ D~ to a heat-emitting object moving about its field of view; a hAnArA~s filter for passing signal6 having a rLe~ue~ey ';
within a pr~A~t~rm;noA band rh~r~ct~ tic of moving vehicles; and an ;nA;rAtnr for ;n,l;c~r;nq the pre6ence of wo gs/~ 2 1 8 ~ S 2 3 PCT~C~95~00134 an object upon lPtect; nn of a signal in said prP-lPtP~;nP~ band The dPt~qctor ~rrnr~l;n~ to the invention is - responfiive to the heat gPnPrAted by the engine of the 5 trailing vehicle. ~ simple low cost passive infrared motion sensor, developed for the home security market, is preferred. A suitable fiensor i5 dual element lithium r~nt~lAte crystal with a low noise EET transistor mounted on a ~ e and ~nrlnF~ in a metal housing with a 10 silicon window having part number ~iEIMANN I~I 958.
Such a sensor has a Fresnel lenfi with well defined lobefi . The lithium tAntAl Ate crystals discharge when infrared r~ t; nn falls on them. ~he~ an object moves acrosfi the field of view of the ~lPtPCtn-, it moves across 15 the ~ oll~e lobea so as to ~pn~ tp an output signal. If the two objects are stationary relative to each other, no output signal is produced.
The vehicle carrying the sensor is of course moving along the road. If the road surface were at a uniform 20 temperature, it would be produce no output signal. In rr~ct; rP, due to differential heating the road surface does produce an output signal at the d~t~ctnr that can be as large as that caused by the trailing vehicle. It has been found, however, that differential heating causes a 25 ~ict;nrtly aifferent signature from a moving vehicle ~:Pn~rAl 7y road signals r--;~---; ly lie in the fre~auency range below 0 51Iz. These signals are mostly P~r~ Pd by the b~n~lr~ filter.
When two vehicles are traveling in parallel along 30 the highway, the random motion of the trailing vehicle across the field of view of the ~lPtPctor will result in the ~lPt~rt; c n of the trailing vehicle even if the two vehicles are moving along the road at the same speed Such a ~7PtPctnr can be made at ~l ~y low cost 35 due in part to the fact that motion ~ensors are mabb w095~s322 2~8~52~ PCJ/C~9SJ00134 _ 4 _ !
!
produced for the security market. The sensors are rugged and consume low power since the control circuitry can be made using CMOS devices. Using lithium batteries, the battery life is P~ortP~a to exceed si~ months rnnt;mlcnls 5 use under average nr~r~tinr~ conditions. It is envisaged that the device will be ;itt~rhoa, preferably adhesively, to the side view mirrors of a vehicle and left pP~-nPntly on. In the idle state, the current drair. will be very small indeed When a vehicle i8 detected, a light-emitting diode will be ;11 n2ted, and this will be visible through the side ~indow from the driver~s pof~;t;nn Unlike most infrared sensing devices working in the reguired t ~ tllre range, the inventive device does not 15 reguire a chopper, cryogenic cooling unit, or ~o~-~n;
lenses. Only a very si~ple s;~n~;n~ Cnna~it;nn;n~ circuit is reguired.
The Fresnel lenses are preferably made of polyethylene.
An important preferred aspect of the irvention is the ability to adapt to rh~n~; n~ ~ t.Pnrnl r,~; r~l cnnla;t;nn~. For example, in periods of heavy rain, car si ~ eS are reduced due to the cooling effect of rain.
Fortunately, the road signature is also reduced due to the fact that the thermal mass of the rain evens out the t- L~ e v~r;Pt;nn~ in the road surface. In the preferred ~ the invention exploits this effect to adaptively adjust the threshold at which a vehicle is considered present lalorona;n r on the nu~ber of noise events ~lotectecl below the present threshold in a pr~ torm;no~l period of time For examplê, if a large number of noise events are flotectod, the threshold is raised . If only a f ew are detected the threshold is lowered This makes the flotertnr more sensitive, but only w0 9~22 2 1 8 ~ ~ 2 3 PCT/C~95/00134 when there is relatively little road noise, for e~ample during periods of heavy rain.
The invention also provides a method of detecting the presence of an object device for ClPtPf~;n~ the presence of an object in the blind Epot of a moving vehicle, characterized in that it co~,prises directing a passive infrared sensor toward the blind spot, said infrared sensor gPnPrZ~t;n~ a signal in response to a heat-emitting object moving about its field of view;
passing signals through a ~ filter for having a ~rPq-lfnry within a prp~lptp~;np~ band rh~r~ftPr; ~tic of moving vehicles; and ;n~ qting the presence of an object upon ~lPtert;r-n of a signal in said rrPtlPtPrm;nP~ band.
The invention will now be ~lP~hPtl in n~ore detail, by way of example only, with reference to the -'3f- ~ ying drawings, in which~
Figure 1 is a plan view showing three vehicles moving along adj acent lanes in a highway;
Figure 2 i8 a rear view of the vehicles shown in 2 0 Figure 1;
Figure 3 ifi a ~ ; c view showing the angular ~o--s~ of the infrared ~l~PtP~ tnr;
Figure 4a is a circuit diagram of the signal conditioning circuit;
Figures 4b to 4f show the signal at various stages in the signal cnn~l;t;on;n~ circuit; and Figure S shows the voltage regulator for the conditioning circuit;
Figure 6 shows the system field o~ view in the direction of travel in more detail;
Figure 7 shows the ~ ;Pr frequency response of a second . ';
i WO 95/25322 2 18 ~ ~ 2 3 PC'r~CA9~/0013~
Figure 8 is a system block diagram of the second ' o~
Figure 9 is a top level flow chart describing the op~rA~ t; nn of the second r--hotA~
Figure 10 is a noise ~ flow chart for the second `~
Figure 11 is a flow chart showing the car detection ~rati nn of the second ~
Figure 12 is a flow chart tA~ rih;n~ the threshold setting operation;
Figure 13 shows the lens cnnf;~lr~At;nn in elevational view; and Figure 14 shows the lens cnnf;~ Ati~n in plan view;
and Figure 15 is a ~ t~ d circuit diagram of the second: A ' ~ ~
Referring now to Figure 1, vehicles 7, 8 and 9 are shown mo~ring along adjacent lanes of a highway, with vehicles 8 and 9 in the blind spot on either side of 20 vehicle 7.
Vehicle 7 haæ side view mirrors 1, 2 with respective passive infrared d~tectnr~ la, 2a mounted thereon. I~ach infrared d~tect~r ha8 a hr'r;-'''ntAl field of view Q. The field of view of n~otectnr la has respective outer and 25 inner edges 3, 4, whereas the detector 2a has a field of view ~ with respect to inner and outer edges 5, 6. These edge8 are chosen to outline the vehicle blind spot Figure 2 shows the same layout from the rear, and thus shows the field of view ~ of the detectors la, 2a in 30 the vertical plane. AS will be apparent from Figures 1 and 2, the ~ tPntnrs la, 2a have a generally ' ~d directed conical field of view covering the vehicle blind WO 95125322 2 1 8 ~ S 2 3 PCr/CA9510013~ ~
8pOt. Vehicles outside this conical field of view are not normally detected.
The ~lPtertnrs la, 2a are normally mounted on the side view mirrors with an adhesive. The detectors include 5 red light-~m;t~;n~ diodes that are visible from the driver's position and that ;ll n~te when a moving heat-emitting source is detected in the field of view ~, ~ of the ~lPtectnrs la, 2a. This alerts the driver to the presence of a vehicle in the blind spot, although before 10 switching lanes the driver should still make a guick visual check by glancing over his shoulder The passive infrared motion ~letect~rs employed in the device have lenses that give an angular response as shown in Figure 3, that is they have a series of radial 15 lobes 10 in the circumf erential direction . This means that the detector has its greatest response along radii a, c, with a minimum along radius b between the radii a and c. The crystals are ~ P~7 80 that a st~t;nn;~ry object pr~7llr~ a ~ero ~utput signal.
As an object moves across the field of view ~rom a to c, the r~7;~inn received by the crystals within the t~ctnr passes through a minimum at b maYimUm at c. mis creates an output signal from the crystals, which in the invention is used to detect the presence of an object.
me relative ~ of the obj ect and detector is caused in part the random motion of the trailing vehicle across the f ield of view of the detector.
This output signal is conditioned by the Cnn~7;~;nn;n~ circuit 5hown in Figure 4a FPfPrrins now to Figure 4, the signal conditioning circuit comprises a clPte-rnr 20, a filter _7;f;Pr 30, an . lif;Gr 40, a ~ _ !nr 50 and a monostable circuit ~0. The cl~otPctor ;nnlll~7P,c: the passive infrared sen50r 21 which is 8llrr~;
with steady voltage V2 provided by the voltage re~ nr shown in Figure 5 . The voltage V2 is s~lppl; P~ through WO 95f25322 2 1 ~ 5 S 2 3 pCTlC~.9510013J, I
series resistors Rl, R2. These resistors in conjunction with the capacitor C, provide a ripple-_ree voltage supply to the sensor 21 The output voltage of the detector 20, which is in 5 the microvolt range, i8 shown in Figure 4a When a target is ~l~t~ct~l, the spike 22 occurs.
The filter/ _l;f;Pr 30 ~r;~ two np~r~t;o ~mrl;f;~rF: 31, 32, which form a band pass filter that matches the output L- e.~ y response of the infrared 10 sensor and rl;~rr;m;n~tes vehicle response from road noise. The circuit also provides a s;rJn;fir~nt amount of gain, providing an output signal in the millivolt range as shown in Figure 4b The output of circuit 30 is applied to ~ r 15 circuit 40, which comprises opPri~t;nn~l l;fi"r 41 This provides further l;f;r~t;rn and also DC filtering through ~r~r; tnr C8 . The output voltage is offset with a voltage provided by resistor network Rll and R12 The output of _ l; f; ~r circuit 40, which is shown in Figure 20 4c, is a circuit in the millivolt range.
The output _l;f;or 40 is applied to co~parator 50, ~- ~;n~ r~rat;onzll, _l;f;-~r~ 51, 52. ~'~ _ r,r 50 is a ~q~r;~ n-making circuit that defines upper and lower bounds of thè input signa~ (Figure 4d). These are set 25 with variable resistor R15, which therefore sets the sensitivity of the circuit. When the - - ~nr 50 registers the target, due to the signal falling outside the upper and lower bounds, as shown in Figure 4d, the r produces a _alling edge voltage signal of 30 small ~ r~tirn at its output. This filter signal is in the volt range and is applied to _ ~hle m~ultivibrator 60, which is a falling edge triggered circuit used to ~ -prolong the duration of the output signal of the c _ rr me output signal, shown in figure 4e, is an 35 output pulse whose ~lllr~tirn is set by resistor R20 and WO 95/2S322 pCTlC~9~/0013~1 ~ ` 2185S23 9.
capacitor Cll The ontput o~ monostable 60 is a voltage Gignal in the volt range, which is used to drive LED 62 that acts as a visual ;nA;c~trr to the driver of the presence of a target.
The conditioning circuit shown in Figure 4 is implemented in CMOS and therefore has very low power cv~u,~ion. This i8 also helped by the fact that it i8 purely a passive, non-r~A;~tin~ device The detector normally operates in the 6 to 14 micron 10 long wave infrared ~ t;nn and is ~Pn~r~l ly responsive to the heat emitted by the engines of moving vehicles. It has bee~ found that the device responds well to vehicle engines with minimal false ;nA;r~;r,nc While the device has been desig~ed particularly with 15 ~ ' 1P~ in mind, it can be applied to other applications, for example aircraft ~l;n~t;oncl where there is a need to detect the yL~5~:uc~ of heat-P"~;tt;
targets The d~tertnrs are ~tt~rh~d to the side mirrors by a 20 durable automotive adhesive. Since they are self-rnn~;n~l and battery QpGr~tPd, no wiring or electrical rnnnPct;rn to the vehicle PlPr~ric~l system is required.
This means they can be distrih~ltPd as low-cost accessories for easy non-invasive ~ ;r~t;nn by the 25 vehicle owner. ~11 he has to do is stick the device in the appropriate poc;~;nn where it is visible from the driver~s pos;r;on through the vehicle window By using a lithium battery, rr,nt;mlnllc opPr~t;~r,n in excess of six months can be achieved. The device is not 30 designed to be switched off. When no target is detected, the current con~, , ; r,n is nominal .
If desired, an ~AA;t;nn~l LED having a different color, such as a amber LED, can be provided to give early warning of a low battery condition.
WO 95/25322 2 1 8 ;~ PCT/CA9~10013.
The optics of the passive ;nfr~rPcl detector will now be discussed in more detail with reference to Figures 6, 13 and 14 This infrared detector could be used in either the first: -' discussed above or in the second 5 ~mhoA1 - to be described below me infrared A~t~rtor only responds to changes in observed t~ _ t e across its field of view. Thus, it is only pOSS;hl.Q for the system to detect objects which cross the field of view. Objects colaing straight towards 10 the 6ensor produce little or now response. For this reason the FoV is angled out from the vehicle direction by about 20 +5~ so that vehicles entering the blind spot actual are f orced to cross the FoV.
Secondly the optimum focal length has been found to 15 be about 25 mm. Shorter focal lengths give a larger FoV
~field of view), but produce a lower effective car frequency ~ign~tl~re. miS makes ~r~r~t;nn of car and road ~ S A;~'f;rl~1t or ~ -_ hl-o, Longer focal lengths have several disadvantages:
a) me llaL~ L spot beam requires better alignment .
b) The beam may not cover the hot spot on the car.
c) More lens ~ are required to give the reguired hnr~7rmt~7 coverage.
d~ A larger physical size of the unit is required to house the larger optics.
The optics is ;3r~ to give the FoV shown in Pigure 6. The ~1;5 must be fairly precise to get this FoV Three angles are involved which can be termed 30 yaw, pitch, and roll. Yaw A~t~rm;nF~ the Tlnr;7-~nt~1 FoV
and is least critical of the three It is est~hl i ch~A by the user simply by aligning a reference line towards the rear of the car. Tnl ~r~nce is + 5 . The roll angle Al~t~rmin-~: the extent to which the FoV extends to the , w09s~22 2 1 8 ~ ~2 3 PCI/C~ 95/01)13~ i ~' - 11 -side of the car. Ideally the FoV of view would be limited to the adjacent lane (3.5 m) In fact, it is chosen to extend slightly beyond this so that sufficient signature is picked up f rom cars in the blind spot . me result is 5 that ocr~qinn~lly there will be triggering from cars one lane over Roll angle should be 15 ~ 2. Pitch i8 the most r~r;t;C~l angle and ~7PtPrm;nPq h~q1c~11y how far the FoV extends behind the car . If it is too high ob~ ects very far away (b7~ 7;n~q, setting sun etc.) will give 10 false triggers. If it is too low the vehicle will not be ~7PtectPfl until it is well into the blind spot. Pitch angle is set to 1.5 i 1.
Pitch and roll angles are set by the user placing a circular level on a surface of the device which when 15 level is set to give the correct roll and pitch angles.
me device la, 2a uses eight lens elementa (i. . .viii) to give h~r; ~nt~l coverage o~ about 60, as shown in Figure 13 The second: ' ' , as shown i~ Figure 8, has a 20 passive infrared detector 70, a hanflr~qq ,l;f;Pr ?1, a detector circuit 72, an LED flasher 73, and a noise event counter 74.
The: l;f;Pr 71 has a specific b~nflr;-qq l~h~rPrtPr;qtic to provide near optim 1 dis~r;m;n~t;on 25 between vehicle and road ~ackground signatures. It has been detern7ined P~pPr; lly that with proper optical alignment, the electronic siy~Lu eb of vehicles lie rr;r-r;7y in the region above 0.5 Erz~ while the electronic s;~n~t~res of the road background lie 30 primarily below O.s ~z In bright sunshine because of differential heating o~ the road surface, the ba~ylvu~d signature can easily be as large as that of a vehicle so that it is vital that these siy~ Lu~ es be filtered out. The device has in fact 35 three filters with high pass cut offs at 0 08, 0 7 and -wog~322 2 1 8 5 ~ 2 3 pCI~/CA95J00i3~ `
O . 7 ~Iz, respectively. As well a second order low pass filter cut off at 4.2 ~z is used to limit high fre~auency noise. The filter response is shown in Fiy-ure 7.
The ~; ~n~tllre received from cars i8 strongly 5 r1~r~n~lPnt on weather cnn~;tinn~. Particularly in medium to heavy rain, the &ignature from vehicles can be .' ;r~qlly reduced. Fortunately, it is possihle for the device to ~ t~rm;n~ when this ~nni;t;~n eYists by nitoring h~ J, ,u i noise as the h~rk~rolln~l sig~ature ~0 is reduced as well during rain - i . e . the road tends to be of re uni~orm t ~ I._LaLUL~:: due to the high thermal - mass of the rain water.
The blind spot elPte~ctnr takes advanLcly~= of this e__ect by collnt;n~ noise values over a given threshold in 15 the noise event counter 74. ~fter a l~L~ ;n~ period, a threshold is chosen that depends on the number of noise counts over the roise threshold. Eligher counts give higher thresholds The period is ~t~n;nP~l by rmlnt;ng the numher of samples below the lowest possible car 20 cl~tP~-t;~n threshold. Thus, the St~t;~t;r~ are not upset by the presence or absence of vehicles in the blind spot.
Sper;f;r~lly, with the ,,l;f;~r gain set to 66 dB
the noise threshold used is 30 mv. The po~3;hl~ cæ
detection thresholds are 50 mv, 100 mv, 150 mv and 200 25 mv me count is done to a m~ximum of 32 events below 50 mv Each event is sampled for about 800 msec so that a new threshold is chosen about every 25 sec if no events over 50 mv occur. The threshold for the next 25 sec interval is set based on the numher of events between 30 30 and 50 mv as follows:
less than 3 events m = 50 mv between 3 and 7 events m = loo mv between ~ and 20 events m = 150 mv more than 20 events Th = 200 mv WO 95125322 2 1 8 5 S 2 3 PCT~CA95/00134 A time out check is alGO ;~r7 ~-1 to prevent the system locking up due to constant noise or car signatures over 50 mv. After one minute of this condition, the threshold is set to 200 mv.
The detailed ortPr~t;nn of the second ~ - , which is mieLu~LuCeSSOr based, is illustrated in Figures 9 to 12.
The detailed circuitry for the second: ' ' is shown in Figure 15 The circuit is controlled by microprocessor 100, which is a Motorola 6805 A signal from passive infrared ~9Ftecto~ 101 is fed through operational ~ ~ 1 i f i ~~~ 102, 103, which also act as b~n-lr~s filters. The output of; _l;fi~r 103 is fed to op~rFIt;nn~l: 1ifi-~rS 104, 105, which acts as ~ , ~ o~. Switches 106 provide the threshold adj__ circuitry.
The invention also has other ~rrlir~ti,~nc, such as school bus child detectors. An inte~r~t~d Multiple unit could cover a long vehicle, such as tractor trailers.
With the current invention, pickup of shadows from overpasses call occur, in particular on sunny days. This is because of the cooler road t ~ ~ under the underpass. It is possible to -~ e for this hy having two d~tPctnrs with one pointing straight down at the road to establish the ~le~ell~e of a shadow. This information can then be, n~ with the data from the car detection sensor to reduce the ~tert; nn of shadows .
The current iIlvention takes advantage of the relative motion of the two vehicles to produce the ~l~tertion signal Normally in most driving s;tll~t;nn~:
this is s~lf~in;~nt to give a very high prnh~hil;ty of detection. }Iowever it is conceivable, ~pe~;A~ly under heavy rain when car s; ~n~tllres are reduced, that relative motion may not be enough to trigger the device This 35 problem can be uveLc by me~h~nir~lly vibrating the WO 95125322 2 1 8 ~ S 2 3 PCT/C~95/00l34 mirror, le~6 or 5ensor to provide a scanning motion of the car ~ig ~eOre ac~o~ ehe iececc~r.
~'
Claims (19)
1. A device for detecting the presence of an object in the blind spot of a vehicle, characterized in that it a passive infrared motion sensor mountable on the vehicle so as to have its field of view directed toward the blind spot, said infrared sensor generating a signal in response to a heat-emitting object moving about its field of view; a bandpass filter for passing signals having a frequency within a predetermined band characteristic of moving vehicles; and an indicator for indicating the presence of an object upon detection of a signal in said predetermined band.
2. A device as claimed in claim 1, characterized in that said infrared detector further comprises a multi-lobe lens defining said field of view, said multi-lobe lens enhancing variations in said signal as the heat-emitting object moves across said field of view.
3. A device as claimed in claim 2, characterized in that said multi-lobe lens defines a generally cone-shaped field of view directable downward to the side of the vehicle.
4. A device as claimed in claim 2, characterized in that the field of view of said multi-lobe lens is angled out from the vehicle direction by about 20° 5° so that vehicles entering the blind spot are forced to cross the field of view.
5. A device as claimed in claim 3, characterized in that said lens is a Fresnel lens.
6. A device as claimed in claim 5, characterized in that said Fresnel lens is made of polyethylene.
7. A device as claimed in claim 1, characterized in that said sensor is a dual element Lithium Tantalate crystal.
8 A device as claimed in any one of claims 1 to 7, characterized in that it further comprises a threshold detector, said threshold indicator only indicating the presence of an object when said signal exceeds said threshold.
9. A device as claimed in claim 8, characterized in that it further comprises means for adaptively adjusting said threshold in response to changing road conditions
10. A device as claimed in claim 9, characterized in that said means for adaptively adjusting said threshold comprises a noise event counter, which counts the number of noise events below the present threshold within a predetermined period and adjusts said threshold in accordance with the number of noise counts within said predetermined period,
11. A device as claimed in claim 1, which is a self-contained unit mountable on an exterior portion of said vehicle.
12. A device as claimed in claim 11, characterized in that said self-contained unit is adhesively mountable on said exterior portion.
13. A device as claimed in claim 11, characterized in that said self-contained unit is adhesively mountable onto a side mirror of the vehicle
14. A device as claimed in claim 1, characterized in that said indicator comprises a light-emitting device.
15. A device as claimed in claim 14, characterized in that said light-emitting device is a light-emitting diode.
16. A method of detecting the presence of an object device for detecting the presence of an object in the blind spot of a moving vehicle, characterized in that it comprises directing a passive infrared motion sensor toward the blind spot, said infrared sensor generating a signal in response to a heat-emitting object moving about its field of view; passing signals through a bandpass filter for having a frequency within a predetermined band characteristic of moving vehicles; and indicating the presence of an object upon detection of a signal in said predetermined band.
17. A method as claimed in claim 16, characterized in that the presence of an object is only indicated when said signal exceeds a predetermined threshold.
18. A method as claimed in claim 17, characterized in that said threshold is adaptively adjusted in response to changing road conditions.
19. A device as claimed in claim 18, characterized in that the number of noise events below the present threshold within a predetermined period are counted, and said threshold is adjusted in accordance with the number of noise counts within said predetermined period.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US21276594A | 1994-03-15 | 1994-03-15 | |
| US08/212,765 | 1994-03-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2185523A1 true CA2185523A1 (en) | 1995-09-21 |
Family
ID=22792339
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002185523A Abandoned CA2185523A1 (en) | 1994-03-15 | 1995-03-14 | Blind spot detector |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU1886695A (en) |
| CA (1) | CA2185523A1 (en) |
| WO (1) | WO1995025322A1 (en) |
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| DE102009040003A1 (en) | 2009-09-03 | 2011-03-10 | Valeo Schalter Und Sensoren Gmbh | Method for classifying object present in dead angle portion of motor vehicle, involves using sensor unit of motor vehicle (1) and determining two distance values by sensor unit for objects to be classified |
| DE102010018038B4 (en) | 2010-04-23 | 2023-08-10 | Valeo Schalter Und Sensoren Gmbh | Method for warning a driver of a vehicle of the presence of objects in a blind spot area and corresponding driver assistance device |
| WO2013034182A1 (en) * | 2011-09-08 | 2013-03-14 | Valeo Schalter Und Sensoren Gmbh | Method for creating a vehicle surroundings map, driver assistance device, and vehicle having a driver assistance device |
| US9916014B2 (en) | 2014-04-11 | 2018-03-13 | Continental Automotive Systems, Inc. | Display module with integrated proximity sensor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4321594A (en) * | 1979-11-01 | 1982-03-23 | American District Telegraph Company | Passive infrared detector |
| FR2608777B1 (en) * | 1986-12-23 | 1989-03-24 | Trt Telecom Radio Electr | INTRUSION DETECTION AND RECOGNITION DEVICE FOR LAND VEHICLES |
-
1995
- 1995-03-14 AU AU18866/95A patent/AU1886695A/en not_active Abandoned
- 1995-03-14 WO PCT/CA1995/000134 patent/WO1995025322A1/en active Application Filing
- 1995-03-14 CA CA002185523A patent/CA2185523A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1995025322A1 (en) | 1995-09-21 |
| AU1886695A (en) | 1995-10-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |