5,708,584
`[11] Patent Number:
`United States Patent
`Doi et al.
`[45] Date of Patent:
`Jan. 13, 1998
`
`
`[19]
`
`USOOS708584A
`
`[54] VEHICLE RUNNING MODE DETECTING
`SYSTEM
`
`FOREIGN PATENT DOCUMENTS
`61-146644
`7/1996
`Japan.
`
`[75]
`
`Inventors: Ayumu Doi; Yasnnori Yamamoto;
`Hideki Nishitake; Tomohiko Adachi.
`all of Hiroshima-ken. Japan
`
`[73] Assignee: Mazda Motor Corporation,
`Hmm’ “Pa"
`
`[21] Appl. No.: 525,218
`
`[22] Filed:
`Sep. 8, 1995
`[30]
`Foreign Application Priority Data
`
`Japan .................................... 6—220294
`[JP]
`Sep. 14. 1994
`[51]
`Int. CL6 ........................................................ 3601‘ 8/32
`[52] U.S. Cl. .................................... SIM/426.044; 364/461;
`180/169; 130/170; 340/903
`[5 8] Field of Search ..................... 364/426.041. 426.044.
`364/460. 451. 565; 180/167—170. 176-179;
`123/350. 352; 342/454. 455‘, 340/901 904
`_
`References Cited
`u_s_ PATENT DOCUMENTS
`
`[56]
`
`
`11/1986 Etch ........................................ 180/169
`4,621,705
`5,053,979 1011991 Etoh ..............
`364/426044
`
`5,396,426
`3/1995 Hibino et a1.
`.. 364/426044
`5,420,792
`5/1995 Bntsuen et a1.
`......................... 364/461
`
`Primary Examiner—Gary Chin
`Anomey, Agent, or Firm—Sixbey. Friedman. beedom &
`Ferguson. RC; Gerald J. Ferguson. Jr.
`[57]
`ABSTRACT
`
`In a vehicle running mode detecting system. a relative speed
`of a vehicle. equipped with the vehicle running mode
`detecting system. to a forward object is calculated on the
`basis of a time elapsed from a reference time based on which
`the time elapsed is measured and a change in the distance
`between the vehicle and the forward object during the time
`elapsed. Whether the vehicle is running in a constant dis-
`tance mode where the distance between the vehicle and the
`forward object is kept substantially constant or in a varying
`distance mode where the vehicle is accelerating or deceler-
`ating relative to the forward object and the distance between
`the vehicle and the forward object is varying is determined
`on the basis of the change in the distance between the
`vehicle and the forward object. The reference time is
`updated less frequently when the vehicle is running in the
`constant distance mode than when the vehicle is running in
`the varying distance mode.
`
`9 Claims, 5 Drawing Sheets
`
`
`-
`25.______._--
`
`6
`
`HEADUP
`DISPLAY
`
`
`
`OBJECT RECOGNITION
`i
`
`
`
`3
`
`RADAR HEAD
`UN IT
`
`
`
`VEHICLE
`SPEED SENSOR
`
`MEANS
`
`:
`
`
`DESTRUCTION
`
`DETERMINING
`
`
`MEANS
`
`
`
`
`
`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`

`

`US. Patent
`
`Jan. 13, 1998
`
`Sheet 1 of 5
`
`5,708,584
`
`
`
`
`
` HEADUF’
`
`
`
`DISPLAY
`
`
`
` VEHICLE
`CONTROL
`
`CONTROL
`
`U NIT
`
`
`
`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`

`

`US. Patent
`
`89
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`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`
`
`
`

`

`US. Patent
`
`Jan. 13, 1993
`
`Sheet 3 of 5
`
`5,708,584
`
`FIG.4
`
`START
`
`Ltn INPUT
`
`$1
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`
`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`

`

`US. Patent
`
`Jan. 13, 1998
`
`Sheet 4 of 5
`
`5,708,584
`
`FIG.5
`
`
`
`d(i)=L(i)—L(i-H
`
`dti—1)=L(i-1)-L(i*2)
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`ACCELERATION
`
`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`

`

`US. Patent
`
`Jan. 13, 1993
`
`Sheet 5 of 5
`
`5,708,584
`
`(SEC)
`
`
`
`TIMEELAPSED
`
`DISTANCE (m)
`
`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`

`

`5,708,5 84
`
`1
`VEHICLE RUNNING MODE DETECTING
`SYSTEM
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`This invention relates a vehicle running mode detecting
`system which is provided with a relative speed calculating
`means which calculates the relative speed of a vehicle to a
`forward object being ahead of the vehicle in the way on the
`basis of a time elapsed from a reference time and a change
`in the distance between the vehicle and the forward object
`during the time elapsed.
`2. Description of the Related Art
`As disclosed, for instance,
`in Japanese Unexamined
`Patent Publication No. 61 (1986)—146644, there has been
`known a vehicle running mode detecting system in which
`the relative speed of a vehicle to the forward vehicle running
`ahead thereof is calculated on the basis of changes in the
`distance between the vehicles during difierent time intervals,
`thereby eliminating necessity of additional relative speed
`calculating means.
`However in the system, since the relative speed is uni-
`formly calculated independently from the running mode of
`the vehicle. i.e., whether the vehicle is running substantially
`at a constant distance from the forward vehicle or at a
`decreasing or increasing distance from the forward vehicle,
`efficiency of calculating the relative speed is low.
`
`SUMMARY OF THE INVENTION
`
`In View of the foregoing observations and description, the
`primary object of the present invention is to provide a
`vehicle running mode detecting system which can detect the
`relative speed of a vehicle to a forward object (e.g., a
`forward vehicle) at a high efficiency.
`In accordance with one aspect of the present invention.
`there is provided a vehicle running mode detecting system
`comprising a relative speed calculating means which calcu—
`lates the relative speed of a vehicle, equipped with the
`vehicle running mode detecting system, to a forward object
`on the basis of a time elapsed from a reference time based
`on which the time elapsed is measured and a change in the
`distance between the vehicle and the forward object during
`the time elapsed, a running mode determining means which
`determines whether the vehicle is running in a constant
`distance mode where the distance between the vehicle and
`the forward object is kept substantially constant or in a
`varying distance mode where the vehicle is accelerating or
`decelerating relative to the forward object and the distance
`between the vehicle and the forward object is varying on the
`basis of the change in the distance between the vehicle and
`the forward object, and a reference time updating means
`which receives an output of the running mode determining
`means and updates the reference time less frequently when
`the running mode determining means determines that the
`vehicle is running in the constant distance mode than when
`the running mode determining means determines that the
`vehicle is running in the varying distance mode.
`In an embodiment,
`the reference time is updated at
`predetermined intervals which are set longer when the
`running mode determining means determines that
`the
`vehicle is running in the constant distance mode than when
`the running mode determining means determines that the
`vehicle is running in the varying distance mode.
`In another embodiment, the running mode determining
`means determines that the vehicle is running in the constant
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`2
`distance mode unless the distance to the forward object
`decreases or increases continuously.
`In still another embodiment, the running mode determin-
`ing means determines that the vehicle is running in the
`constant distance mode when the change in the distance to
`the forward object is small even if the distance to the
`forward object decreases or increases continuously.
`In still another embodiment, the reference time updating
`means updates the reference time when the running mode
`determining means keeps determining that the vehicle is
`running in the constant distance mode for a time not shorter
`than a predetermined time.
`In accordance with another aspect of the present
`invention. there is provided a vehicle running mode detect—
`ing system comprising a relative speed calculating means
`which calculates the relative speed of a vehicle. equipped
`with the vehicle running mode detecting system, to a for—
`ward object on the basis of a time elapsed from a reference
`time based on which the time elapsed is measured and a
`change in the distance between the vehicle and the forward
`object during the time elapsed. a running mode determining
`means which determines that the vehicle is running in a
`varying distance mode where the vehicle is accelerating or
`decelerating relative to the forward object and the distance
`between the vehicle and the forward object is varying on the
`basis of the change in the distance between the vehicle and
`the forward object. and a reference time updau‘ng means
`which receives an output of the running mode determining
`means and updates the reference time more frequently as the
`degree of acceleration or deceleration of the vehicle
`increases.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view of a vehicle equipped with a
`running control system employing a vehicle running mode
`detecting system in accordance with an embodiment of the
`present invention,
`FIG. 2 is a schematic block diagram of the running control
`system,
`FIG. 3 is a block diagram of the control unit.
`FIG. 4 is a flow chart for illustrating the basic control of
`the control unit,
`
`FIG. 5 is a flow chart for illustrating the manner of
`determining the running mode of the vehicle, and
`FIG. 6 is a view for illustrating the manner of determining
`the mnning mode of the vehicle.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`In FIG. 1. a vehicle I is equipped with a running control
`system comprising a radar head unit 3 mounted in the front
`of the vehicle body 2, a control unit 4. a vehicle speed sensor
`5, a headup display 6, an alarm 7 (FIG. 2) and a vehicle
`control device 8.
`
`The radar head unit 3 emits a pulse laser beam (as a radar
`wave) forward of the vehicle 1 from a source and receives
`reflected light beam reflected by a forward object in the way
`such as a vehicle, thereby measuring the distance from the
`vehicle 1 to the forward object. The radar head unit 3 is of
`a scan type which causes a pulse laser beam, which is small
`in width and like a sector in a vertical cross-section, to scan
`horizontally through a relatively wide angle.
`As shown in FIG. 2, signals from the radar head unit 3 and
`the vehicle speed sensor 5 which detects the running speed
`
`MERCEDES
`
`EXHIBIT 1004
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`MERCEDES
`EXHIBIT 1004
`
`

`

`3
`
`5 .7085 84
`
`4
`
`of the vehicle 1 are input into the control unit 4 and the
`running mode of the vehicle 1 is determined by the control
`unit 4 and shown by the headup display 6. When it is
`determined that the forward object is an obstruction for the
`vehicle 1 to clear. the alarm 7 operates and the vehicle
`control device 8 automatically causes brakes 8a of the
`vehicle 1 to operate to decelerate the vehicle 1.
`As shown in FIG. 3. the control unit 4 comprises an object
`recognition means 25 which receives a signal from the radar
`head unit 3 and recognizes a forward object such as a
`forward vehicle in the way of the vehicle 1. a relative speed
`calculating means 22 which receives signals from the object
`recognition means 25 and a timer means 21 and calculates
`the relative speed of the vehicle 1 to the forward object on
`the basis of a time elapsed from a reference time based on
`which the time elapsed is measured and a change in the
`distance between the vehicle 1 and the forward object during
`the time elapsed. a running mode determining means 23
`which receives outputs of the object recognition means 25
`and the vehicle speed sensor 5 and determines whether the
`vehicle 1 is running in a constant distance mode where the
`distance between the vehicle 1 and the forward object is kept
`substantially constant or in a varying distance mode where
`the vehicle 1 is accelerating or decelerating relative to the
`forward object and the distance between the vehicle 1 and
`the forward object is varying. and a reference time updating
`means 24 which receives an output of the running mode
`determining means 23 and sets the reference time updating
`frequency by the relative speed calculating means 22 lower
`when the running mode determining means 23 determines
`that the vehicle 1 is running in the constant distance mode
`than when the running mode determining means 23 deter—
`mines that the vehicle 1 is running in the varying distance
`mode.
`
`The control unit 4 further comprises an obstruction deter-
`mining means 26 which receives outputs of the object
`recognition means 25 and the relative speed calculating
`means 22 and determines whether the forward object is an
`obstruction for the vehicle 1 to clear.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`distances L(i-19) to L(i-l) are stored by the object recogni-
`tion means 25.
`
`Then the running mode (RIM) of the vehicle 1 is deter-
`mined on the basis of the change in the vehicle-to-vehicle
`distance calculated on the basis of the output of the object
`recognition means 25 and the running speed of the vehicle
`1 detected by the vehicle speed sensor 5. (step S2) Then the
`running mode determining means determines whether the
`current running mode is the constant distance mode (CDM)
`or the varying distance mode (VDM). (step S3)
`When it is determined that the current running mode is
`constant distance mode, it is registered in the obstruction
`determining means 26. (step S4) Thereafter it is determined
`whether the preceding running mode (the running mode one
`point before) was the constant distance mode. (step SS)
`When it is determined that the preceding running mode was
`also the constant distance mode. it is determined that the
`current base point (or the refaence time) from which the
`time elapsed is measured is the point which is 21 point
`before. When it is determined in step SS that the preceding
`running mode was not the constant distance mode. that is.
`when the preceding running mode was the varying distance
`mode. the base point is updated to the point 3 point before
`(step S7) and then the relative speed is calculated according
`to the following formula (step SS).
`RF{D(D-L(BP)}/t(i-BP)
`
`wherein Rs represents the relative speed. L(i) represents the
`vehicle-to-vehicle distance at the current point. MBP) rep-
`resents the vehicle-to—vehicle distance at the base point BP
`and t(i—BP) represents the time difference (the time elapsed)
`between the current point and the base point BP.
`For example. assuming that the time elapsed from the
`base point BPl is T] and the change in the vehicle-to-
`vehicle distance during the time T1 is L1 in the part
`indicated at P1 in FIG. 6. the relative speed Rs is L1/I‘l.
`When it is determined in step S6 that the current base
`point is the point which is 21 point before. the base point is
`updated to the point 1 point before (step S9) and then step
`S8 is executed. That is, when the running mode is the
`constant distance mode at successive tow points including
`the current point. the base point is not updated until the
`running mode keeps being the constant distance mode. In
`this particular embodiment. the base point is updated way
`21 points when the running mode keeps being the constant
`distance mode.
`When it is determined in step S3 that the current running
`mode is the varying distance mode. the step 7 is executed
`and the base point BP is updated to the point 3 point before
`after that the current running mode is the varying distance
`mode is registered in the obstruction determining means 26
`in step 810. For example, when the vehicle-to—vehicle
`distance is decreasing. i.e.. when the vehicle 1 is accelerat-
`ing relative to the forward vehicle as in the part indicated at
`P2 in FIG. 6. the base point BP is changed from 131’] to BP2
`and the relative speed Rs is L2/I‘2 assuming that the time
`elapsed from the base point BP2 is T2 and the change in the
`vehicle-to-vehicle distance during the time T2 is L2. Thus
`when the varying distance mode continues. the base point
`BP is constantly updated to BP3. BP4 and so on so that the
`relative speed Rs can be calculated following abrupt change
`in the same.
`
`The running mode determining means 23 determines that
`the vehicle is running in the constant distance mode unless
`the distance to the forward object decreases or increases
`continuously and also determines that the vehicle is running
`in the constant distance mode when the change in the
`distance to the forward object is small even if the distance
`to the forward object decreases or increases continuously.
`Further the running mode determining means 23 determines
`whether the vehicle 1 is accelerating. decelerating or running
`at a constant speed on the basis of the signal fi‘om the vehicle
`speed sensor 5.
`The reference time updating means 24 updates the refer-
`ence time when the running mode determining means 23
`keeps determining that the vehicle 1 is running in the
`constant distance mode for a time not shorter than a prede-
`termined time in order to prevent deterioration in accuracy
`of detecting the relative speed.
`The control by the control unit 4 will be described
`hereinbelow with reference to FIG. 4 assuming that a '
`forward vehicle is recognized as the forward object. In this
`particular example. the object recognition means 25 detects
`the vehicle—to-vehicle distance (the distance between the
`forward vehicle and the vehicle 1) at regular intervals on the
`basis of the signal from the radar head unit 3. In the
`following description. L(i) denotes the current vehicle-to-
`vehicle distance.
`In FIG. 4. the vehicle-to—vehicle distance L(i) is input.
`(step 81) More particularly. the last 19 vehicle-to—vehicle
`
`50
`
`55
`
`65
`
`In step 83. the running mode is determined in the manner
`shown in FIG. 5. That is, the changes in the vehicle-to-
`vehicle distance between each of last three points and the
`preceding point d(i). d(i—l) and d(i—2) are calculated as
`follows. (step Sll)
`
`MERCEDES
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`EXHIBIT 1004
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`

`5,708,584
`
`d(0=L(O-L(i-1)
`d(i-l)=L(i-1)—L(i-2)
`
`d(i-2)=L(i-2)—L(i-3)
`
`Then it is determined whether or not the changes d(i), d(i- l)
`and d(i—2) are all negative or two of them are negative with
`the other being 0. (step 812) When it is determined that the
`changes d(i), d(i-l) and d(i-2) are all negative or two of them
`we negative with the other being 0. it is determined whetha
`the sum of the changes d(i), d(i-l) and d(i—2) is smaller than
`a predetermined value dcl. (step 813) When it is determined
`the former is smaller than the latter, that is, when the change
`in the vehicle-to—vehicle distance is large, it is determined
`that the vehicle 1 is accelerating relative to the forward
`vehicle. (step 814) Otherwise it is determined that the
`vehicle 1 is running at a constant distance from the forward
`vehicle since the degree of acceleration is low. (step SIS)
`When it is not determined in step 812 that the changes
`d(i), d(i—1)) and d(i-2) are all negative or two of them are
`negative with the other being 0. it is determined whether or
`not the changes d(i). d(i-l) and d(i-2) are all positive or two
`of them are positive with the other being 0. (step 816) When
`it is determined that the changes d(i). d(i-l) and d(i-2) are all
`positive or two of them are positive with the other being 0,
`it is determined whether the sum of the changes d(i), d(i- l)
`and d(i-Z) is larger than a predetermined value dc2. (step
`817) When it is determined the former is larger than the
`latter, that is, when the change in the vehicle-to—vehicle
`distance is large,
`it is determined that the vehicle 1 is
`decelerating relative to the forward vehicle.
`(step 818)
`Otherwise it is determined that the vehicle 1 is running at a
`constant distance from the forward vehicle since the degree
`of deceleration is low. (step SIS)
`Thus when all
`the changes in the vehicle-to—vehicle
`distance in the last three intervals are not of the same sign
`(including 0), the running mode is determined to be the
`constant distance mode and the relative speed is calculated
`without changing the base point Further even if all the
`changes in the vehicle-to—vehicle distance in the last three
`intervals are of the same sign (including 0), the change in the
`vehicle-to-vehicle distance is determined to be not abrupt
`and the running mode is determined to be the constant
`distance mode if the absolute value of the sum of the
`changes is smaller than a predetermined value. For example,
`in the part indicated at P3 in FIG. 6, though the three
`successive changes in the vehicle-to-vehicle distance are all
`positive,
`it
`is determined that the running mode is the
`constant distance mode since the change L3 in the elapsed
`time T3 is small. In this case, the relative speed is 1.3/I‘3.
`Thus in the vehicle running mode detecting system of the
`present invenfion, the reference time is updated less fre-
`quently when the vehicle is running in the constant distance
`mode where the relative speed of the vehicle to the forward
`object need not be calculated so accurately than when the
`vehicle is running in a varying distance mode where the
`relative speed should be calculated accurately. Accordingly,
`the elficiency of calculating the relative speed can be
`improved.
`What is claimed is:
`
`1. A vehicle running mode detecting system comprising a
`relative speed calculating means which calculates the rela-
`tive speed of a vehicle, equipped with the vehicle running
`mode detecting system, to a forward object on the basis of
`a time elapsed from a reference time based on which the
`time elapsed is measured and a change in the distance
`between the vehicle and the forward object during the time
`elapsed,
`
`6
`a running mode determining means which determines
`whether the vehicle is running in a constant distance
`mode where the distance between the vehicle and the
`
`forward object is kept substantially constant or in a
`varying distance mode where the vehicle is accelerating
`or decelerating relative to the forward object and the
`distance between the vehicle and the forward object is
`varying on the basis of the change in the distance
`between the vehicle and the forward object. and
`a reference time updating means which receives an output
`of the running mode determining means and updates
`the reference time less frequently when the running
`mode determining means determines that the vehicle is
`running in the constant distance mode than when the
`running mode determining means determines that the
`vehicle is running in the varying distance mode.
`2. A vehicle running mode detecting system as defined in
`claim 1 in which said reference time updating means updates
`the reference time at predetermined intervals which are set
`longer when the running mode determining means deter-
`mines that the vehicle is running in the constant distance
`mode than when the running mode determining means
`determines that the vehicle is running in the varying distance
`mode.
`
`3. A vehicle running mode detecting system as defined in
`claim 2 in which the running mode dew-mining means
`determines that the vehicle is running in the constant dis-
`tance mode unless the distance to the forward object
`decreases or increases continuously.
`4. A vehicle running mode detecting system as defined in
`claim 3 in which the running mode determining means
`determines that the vehicle is running in the constant dis—
`tance mode when the change in the distance to the forward
`object is small even if the distance to the forward object
`decreases or increases continuously.
`S. A vehicle running mode detecting system as defined in
`claim 4 in which the reference time updating means updates
`the reference time when the running mode determining
`means keeps determining that the vehicle is running in the
`constant distance mode for a time not shorter than a prede-
`termined time.
`
`6. A vehicle running mode detecting system as defined in
`claim 1 in which the running mode detainining means
`determines that the vehicle is running in the constant dis-
`tance mode unless the distance to the forward object
`decreases or increases continuously.
`7. A vehicle running mode detecting system as defined in
`claim 1 in which the running mode determining means
`determines that the vehicle is running in the constant dis-
`tance mode when the change in the distance to the forward
`object is small even if the distance to the forward object
`decreases or increases continuously.
`8. A vehicle running mode detecting system as defined in
`claim 1 in which the refa'ence time updating means updates
`the reference time when the running mode determining
`means keeps determining that the vehicle is running in the
`constant distance mode for a time not shoner than a prede-
`termined time.
`
`9. A vehicle running mode detecting system comprising
`a relative speed calculating means which calculates the
`relative speed of a vehicle, equipped with the vehicle
`running mode detecting system, to a forward object on
`the basis of a time elapsed from a reference time based
`on which the time elapsed is measured and a change in
`the distance between the vehicle and the forward object
`during the time elapsed,
`
`5
`
`10
`
`15
`
`2O
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`

`

`5 ,708,5 84
`
`7 ‘
`a running mode determining means which determines a
`degree of acceleration or deceleration of the vehicle
`relative to the forward object and a variation in the
`distance between the vehicle and the forward object on
`the basis of the change in the distance between the
`vehicle and the forward object. and
`
`5
`
`8
`a reference time updating means which receives an output
`of the running mode determining means and updates
`the reference time more frequently as the degree of
`acceleration or deceleration of the vehicle increases.
`
`*
`
`*
`
`*
`
`*
`
`*
`
`MERCEDES
`
`EXHIBIT 1004
`
`MERCEDES
`EXHIBIT 1004
`
`