United States
`Weidman et al.
`
`ent
`
`[19]
`
`[54] TRAFFIC RESPONSIVE SPEED
`CONTROL SYSTEM
`'
`
`.
`[75] Inventors: Joseph S. Weidman, Walled Lake;
`'
`Henry C. Yee, Royal Oak; Jack G.,
`Elliott, Farmington; Zaven Margo-
`Sum’ mmng am a 0 w
`[73] Assigneep The Bendix Corporation’ south?eld,
`Mich‘
`
`‘ B"h,llfM'h.
`
`[22] Filed:
`‘
`'
`[21] Appl' NO" 86’922
`
`Nov. 4, 1970
`
`[52] US. Cl ------------------------------- ~343/7 ED, 130/32-1
`[51] Int- Cl- --------------------------- --G015 9/04, G018 9/46
`[53] Field of Search -----343/7'ED; 180/821, 98, 105;
`'
`354/4
`
`[56]
`
`.
`References cued
`- UNITED STATES PATENTS
`.
`
`[ll]
`
`[45]
`
`3,725,921
`Apr. 3,, 1973
`
`.
`
`..
`
`Primary Examiner-Benjamin A. Borchelt
`Assistant Examiner—G. E. Montone
`Att0rney—Lester L. Hallacher and Flame, Hartz,
`Smith and Thompson
`.
`'
`ABSTRACT
`[57]
`A system for automatically adjusting the speed of a
`vehicle to existing traffic conditions is described. The
`system functions in conjunction with an automatic
`speed control system to maintain a safe‘v following
`distance between vehicles traveling in the same
`direction. A range and range-rate sensor generates
`signals which are indicative of the distance between
`the vehicles, as well as the closing or opening velocity
`of the vehicles. These signals are used to accelerate or
`decelerate the trailing‘ vehicle to maintain a safe and
`optimum distance between the vehicles in accordance
`with the speed of the lead vehicle. The system is non;
`cooperative, so that the lead vehicle need not be
`similarly equipped in order for the system to operate.
`The systemis capable of overriding the speed control
`system within the vehicle but can be overridden by the
`
`MaCMunn . . . . . . . - . . . . . . . . . . . . . . . .
`
`driver when deceleration of acceleration decision is
`
`3,442,347
`3 337 866
`’
`’
`2,804,160
`_ 3,385,964
`3,476,204
`'
`
`""343/7 ED
`5/1969 Hodgson et a1‘ "
`8/1967 Gisonno ........................... ..343/7 ED
`.
`8/1957
`Rashld ............................ ..180/82.1
`5/1968 Gel-an et 3L “
`W343” ED
`11/1969 Westby etal ......................... ..l80/98
`
`executed. Although the system can override (the speed
`.
`control system, the speed set into the speed. control
`.
`_
`'
`system can not be exceeded except by dr1ver override.
`However, overriding of the speed control system by
`the invention system or by driver override does not
`destroy the speed set by the driver.
`'
`30 Claims, 5 DrawingFigures
`
`l'
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`MERCEDES
`EXHIBIT 1016
`
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`MERCEDES
`EXHIBIT 1016
`
`MERCEDES
`EXHIBIT 1016
`
`
`
`

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`ATTORNEY
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`MERCEDES
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`EXHIBIT 1016
`
`MERCEDES
`EXHIBIT 1016
`
`
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`
`
`
`
`
`
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`

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`PATU‘HEDAPRIi I975
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`
`MERCEDES
`EXHIBIT 1016
`
`

`
`PATENTEDAPRS ' I975
`
`sum II BF 4
`
`3,725,921
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`lNVENTORS
`JOSEPH s. WEIDMAN '
`HENRY C. YEE
`JACK G. ELLIOTT
`ZAVEN MARGOS IAN
`8* ,nwwg
`
`I
`
`ATTORNEY
`
`MERCEDES
`EXHIBIT 1016
`
`

`
`3,725,921
`
`1
`TRAFFIC RESPONSIVE SPEED CONTROL
`SYSTEM
`
`CROSS-REFERENCES TO RELATED
`APPLICATIONS AND PATENTS
`
`U. S. Pat. No. 3,455,4ll, entitled AUTOMOBILE
`SPEED CONTROL, by R. W. Carp, et al.
`U. S. Pat. No. 3,659,293 entitled RANGE DETECT
`ING DOPPLER RADAR, by Ra'dhar Gupta.
`10
`U. S. application Ser. No. 75,056, ?led Sept. 24,
`1970, entitled DIPLEX MULTl-FREQUENCY CW
`DOPPLER RADAR, by William R. Faris.
`The above-referenced disclosures are assigned to
`Bendix Corporation, the assignee of the instant applica
`tion, and fully describe subsystems which can op
`tionally be employed in the inventive system.
`
`BACKGROUND OF THE INVENTION
`
`2
`a constant speed can be held for a relatively long period
`of time. However, such a system has little or no safety
`value and does not assist in maintaining smooth traffic
`flow in congested areas.
`Because of the infeasibility of adopting a completely
`automatic collision avoidance system and because the
`presently existing automatic speed control systems are
`lacking in safety features, a type of system which falls
`between the two would constitute a marked improve
`ment over the present state of the art. A system which
`would lie between the afore-described types of systems
`would include a system which would offer automatic
`speed control of the vehicle and simultaneously pro
`vide a means wherein the trailing vehicle is maintained
`at an optimum trailing distance behind the lead vehicle.
`This would greatly improve the flow of traffic through
`congested areas and simultaneously provide some
`safety features, because the driver of the automatically
`controlled vehicle would be presented visual or audible
`signals indicative of potentially hazardous conditions,
`and also because a safe following distance would be
`maintained. However, the system would not attempt to
`completely assume control of the vehicle to avoid all
`types of hazardous conditions.
`
`25
`
`The continual increase in population of vehicles on
`the nation’s roadways emphasizes the need for a system
`for automatic vehicle control which simultaneously
`enhances driver safety and decreases congestion. This
`is particularly true around urban areas where accidents
`and congestion are continually increasing. Several
`types of automatic vehicle control systems of varying
`sophistication have been proposed in the past. The
`most sophisticated type of system is an automatic colli
`sion avoidance system. These systems are intended to
`monitor the highway appearing before the traveling
`vehicle so that hazardous passing or driving conditions
`can be avoided. Accordingly, adriver attempting to
`pass a vehicle will be forewarned or prevented from
`passing if the possibility of a head-on collision with an
`' oncoming vehicle exists. Alternatively, a vehicle travel
`ing in the same direction as the radar-equipped vehicle,
`and which is involved in a collision or suddenly slows
`for some reason, presents a hazardous condition which
`would automatically be avoided by the instantaneous
`braking or turning of the collision avoidance equipped
`vehicle. The collision avoidance system is therefore
`capable of overriding the driver’s attempts at con
`trolling the vehicle in such instances.
`It has also been proposed to ‘adapt a collision
`avoidance system such that it is capable of automati
`cally maintaining a safe traveling distance between
`vehicles traveling in the same direction. Accordingly,
`this type of system would constitute a complete safety
`control package, in that it would avoid head-on and
`rear-end collisions and simultaneously optimize traffic
`flow through congested areas. Although such systems
`are theoretically feasible, they are economically in
`feasible and accordingly have not been adopted as of
`the present date.
`Various types of systems are available for automati
`cally maintainingia preselected velocity for the vehicle.
`These systems are a driver convenience and provide lit
`tle or no safety. The vehicle is held at a preselected
`speed which is chosen by the driver consistent with
`prevailing traffic conditions. This type of system then
`automatically maintains the vehicle at the preselected
`velocity irrespective of road grade, wind conditions,
`and without attention from the driver. However, the
`driver can assume control of the vehicle velocity by
`either braking or accelerating the vehicle at his option.
`This type of system is very convenient for the driver,
`especially for turnpike and long-distance driving where
`
`SUMMARY OF THE INVENTION
`
`The inventive system is directed to an adaptive speed
`control system, and accordingly automatically main
`tains a safe trailing distance between‘ two vehicles. The
`inventive system operates in conjunction with an auto
`matic speed control system, and therefore provides
`both driver convenience and safety features while
`simultaneously assisting in. the optimization of traffic
`flow through congested areas.
`The system includes an active energy source which
`can be optical or microwave, so that energy is trans
`mitted from the system within the trailing vehicle and is
`re?ected back from a leading vehicle. The re?ected
`signal contains information indicative of the range to
`the lead vehicle and the relative velocity of the two
`vehicles. The return signal is then processed to auto
`matically accelerate or decelerate the trailing vehicle
`to maintain an optimum following distance in ac
`cordance with the speed of the lead vehicle. Because
`energy is transmitted from the system and re?ected
`energy is received back, the system is noncooperative
`and therefore does not require an identical system in
`the lead vehicle.
`The system operates in conjunction with an auto
`matic speed control system and is capable of overriding
`the control function of the speed control system so that
`a driver can conveniently set his vehicle to a
`preselected desired speed and automatically maintain
`this speed. When the vehicle comes up upon a slower
`traveling vehicle, the adaptive speed control system au
`toinatically‘slows the trailing vehicle so that it assumes ’
`the speed of the lead vehicle. The controlled vehicle
`will then continue at this speed automatically and will
`accelerate arid decelerate in accordance with the ac‘
`celeration and deceleration of the lead vehicle. How
`ever, if desired, the driver can override the adaptive
`speed control system and pass the lead vehicle at his
`option.
`Because the system is responsive to objects appear- 7
`ing in front of the vehicle, the energy beam width must
`
`35
`
`45
`
`55
`
`60
`
`65
`
`MERCEDES
`EXHIBIT 1016
`
`

`
`3,725,921
`
`3
`be narrow in order to avoid responses from adjacent
`lane objects and fixed roadside objects. When the ener
`gy source is a microwave radar system, this is provided
`by a narrow beam antenna. However, even with a nar
`row beam antenna, there are some instances, such as
`going around curves, in which the radiation beam will
`be aimed at a ?xed roadside target, such as a sign or
`lamppost. The system must therefore incorporate a
`fixed target rejection capability in order to avoid sud
`den decelerations because of erroneous signals caused
`by reflections from such targets.
`The adaptive speed control system should remain in
`sensitive to signals re?ected from targets which are
`present at an excessive range in front of the vehicle.
`This can be done by establishing a threshold for the
`receiver system so that received targets which are
`below a threshold level do not actuate the receiving cir
`cuitry. The inventive system can incorporate a more so
`phisticated cutoff range system, which is more fully
`described hereinafter.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a conceptualblock diagram of an adaptive
`speed control system.
`FIG. 2 is a functional block diagram of the adaptive
`speed control system.
`FIG. 3 is a block diagram of a preferred embodiment
`of the system for generating the throttle control signal.
`FIG. 4 is a block diagram of a preferred embodiment
`of the system for generating the brake control signal.
`FIG. 5 is a graph of the response of a nonlinear am
`plifier used in the system.
`
`20
`
`25
`
`4
`voltages, and accordingly generates an error signal
`when the measured velocity V2 is different from the
`desired velocity V2. The error voltage output from
`Comparator 13, present on Output Lead 21, serves as
`an input to the Accelerator Pedal Control 14, so that
`the velocity of the car is increased or decreased in ac
`cordance with the polarity of the error signal. There
`fore, as the vehicle attempts to change speed in
`response to road grades or wind the vehicle is automati_
`cally maintained at the selected speed by the system.
`Several automatic speed control systems which
`operate in accordance with the above description are
`presently available. However, one system which can be
`used is fully described in U.S. Pat. No. 3,455,41 l.
`
`SENSOR SYSTEM
`
`Sensor System 22, shown in FIG. 1, is used to deter
`mine the range and range-rate between the two vehi
`cles. This system can be optical or microwave but must
`include the capability of transmitting and receiving
`energy which is conveniently generated and detected.
`Because both range and range-rate information are
`required, a Doppler radar system is a convenient means
`of obtaining the required information. A system which
`completely ful?lls the requirements of an adaptive
`speed control system is fully described in US. Pat. No.
`3,659,293, fully referenced hereinabove.
`The Doppler radar system described in the above
`referenced patent application is a Gunn diode Doppler
`radar system where a variable voltage is applied to the
`Gunn diode so that two discreet frequencies are trans
`mitted on a time-sharing basis. The energy re?ected
`from the target therefore creates two Doppler frequen
`cies which form a composite signal. The phase relation
`ship of the two Doppler frequencies is indicative of the
`range between the radar system and the target, while
`the Doppler frequency is directly related to the relative
`velocity between the transmitting antenna and the tar
`get from which the received energy is reflected. The
`range and range-rate data are extracted from the
`received signal and processed to effect the desired
`vehicle control.
`
`DETAILED DESCRIPTION
`
`35
`
`FIG. 1 shows a conceptual block diagram of the
`adaptive speed control system. The speed control
`system, which is indicated generally by reference nu
`meral 10, is divided into two parts, 11 and 12. The por
`tion indicated by numeral 11 indicates the automatic
`speed control system of the convenience type ex
`plained hereinabove, and several types of which are
`available. The portion indicated by reference numeral
`12 shows the circuitry added to the automatic speed
`control system to convert it into an adaptive speed con
`trol system.
`The inventive adaptive speed control system can be
`best understood by ?rst understanding the automatic
`speed control system 11 and the other portions of the
`inventive system which are known in the art.
`
`AUTOMATIC SPEED CONTROL SYSTEM
`The Automatic Speed Control System 11 is intended
`to maintain the forward velocity of the Vehicle 16 at
`any value selected by the driver. This is accomplished
`by placing a reference voltage V2, which is representa
`tive of the desired speed, onto an Input Lead 19 of a
`Signal Comparator 13. The actual speed V2’ of Vehicle
`16 actuates Speedometer 17 of known type, so that a
`measured velocity V2 is the output of the speedometer.
`A sensor, which can be coupled to the speedometer
`cable, generates a voltage proportional to the measured
`velocity V2. This voltage is fed back to Voltage Com
`parator 13. Comparator 13 generates a voltage which is
`proportional to the difference between the two input
`
`45
`
`THE ADAPTIVE SPEED CONTROL SYSTEM v
`The inventive adaptive speed control system shown
`in the conceptual block diagram of FIG. 1 includes the '
`Automatic Speed Control Section 11 and the Adaptive
`Speed Control Section 12. Section 12 includes a Sensor
`System 22, which can be of the type ‘described
`hereinabove, and a Signal Processing Circuit 23 and a
`Brake Pedal Actuator 24.
`Functional Block 27 is used to indicate the geometry
`of the vehicular system; that is, the important parame
`ters of the two vehicles which will result in the required
`range and range-rate information and those which dic
`tate the required control functions. Accordingly,
`Geometry Block 27 is shown receiving an input V2’,
`which is the actual velocity of the radar bearing vehi
`cle. An input is also received from the Leading Car
`Functional Block 26, so that the actual velocity, V1’ of
`. the lead car is input to the system. Because of the
`65 operation of Sensor System 22, the V2’ and V1’ infor
`mation is processed so that range R and range-rate R
`information is generated by the sensor system. Because‘
`the sensor system is also affected by ambient noise and
`
`MERCEDES
`EXHIBIT 1016
`
`

`
`3,725,921
`
`20
`
`25
`
`6
`Absent signal is generated in response to theabsence of
`a Doppler signal, the memory is activated to remember
`the existing signal for a preselected period of time. At
`the expiration of the time a very small accelerate signal
`is generated to very slightly accelerate the vehicle. This
`causes a Doppler signal and also reactivates the Adap
`tive Speed Control. The acceleration resulting from
`this generation is very slight and is not noticeable by
`the occupants of the vehicle.
`Referring again to FIG. 2, it is noted that there is a
`Range Cutoff Input to the Signal Generator 23. The
`Range Cutoff Signal is used to maintain the sensitivity
`of the system to within the maximum desired range,
`such as 250 or 300 feet. A maximum range sensitivity is
`desired in order to prevent the system from functioning
`when distant objects ?rst appear within the line of sight
`of the radar. A system for providing range cutoff is
`described in application Ser. No. 75,056, filed Sept. 24,
`1970. The provision of range cutoff is optional because
`the inherent system sensitivity provides some range cu
`toff capability.
`The Target Present Signal is fed to a Resume Circuit
`31, the output of which actuates Speed Adjust Circuit
`32, so that the automatic speed controloperation of
`System 11 of FIG. 1 can be overridden if necessary.
`Resume Circuit 31 also serves to slightly accelerate the
`vehicle under the zero Doppler condition explained
`hereinabove. Speed Adjust 32 actuates the Speed Con
`trol Electronic Unit 33 and actuates the system.
`Speed Control Unit 33 can be similar to the auto
`matic speed control circuit described in the above
`referenced US. Pat. No. 3,455,41 1. This unit receives
`Driver Control Signals such as On-Off, Accelerate,
`Decelerate, and Memorize signals. Accordingly, the
`driver dictates the operation of the system at his option.
`Furthermore, the circuit receives Driver Override
`Signals, such as Throttle and Brake, so that the system
`is automatically overridden at his option without the
`requirement of additional driver steps beyond those
`which he would ordinarily assume, such as accelerating
`or braking the vehicle by actuation of the appropriate
`
`5
`other errors, Functional Block 28 is used to represent
`these inputs. Sensor System 22 then generates a Range
`Signal R and a Range-Rate Signal R which are input to
`Signal Processor 23. Signal Processor 23 also receives
`the measured velocity V2 of the vehicle from the
`speedometer cable sensor.
`If the range and range-rate information are such that
`the trailing vehicle is falling behind the lead vehicle, or
`is closing at a rate which can be reduced by decreasing
`the vehicle accelerator deflection, a Throttle Error
`Function E is generated and fed to Comparator Circuit
`13. The E signal in Circuit 13 will override any signals
`received from the automatic speed control system and
`cause the vehicle velocity to change, thus causing trail
`ing Vehicle 16 to assume the optimum safe trailing
`distance behind the lead vehicle.
`If the range and range-rate information show that the
`trailing vehicle is closing upon the leading vehicle and
`is within a range which is less than the optimum trailing
`range so that braking is required, a Brake Function E,,
`is generated and fed to the Brake Pedal Actuator 24.
`This input slows the trailing vehicle so that it assumes
`the optimum trailing distance and follows the speed of
`the lead vehicle.
`FIG. 2 is a functional block diagram of the inventive
`adaptive speed control system. The E and El, Signal
`Generator 23 is equivalent to Signal Processing Circuit
`23 shown in FIG. 1. Signal Generator 23 receives a
`Range R input, a Range-Rate R input, an Ap
`’ proach/Recede signal, and a Target Present input from '
`the Sensor System 22 of FIG. 1.
`_
`The Range R and Range-Rate R and Ap
`proach/Recede signals are generated from the Doppler
`information present in the received signal. The Ap
`proach/Recede signal is a signal which is indicative of
`the opening or closing relationship of the two vehicles.
`The Target Present signal is used‘to inform the system
`that a target is present within the operative rangeof the
`system, and therefore indicates that a Doppler signal is
`received and serves to actuate the system and put it
`into the Adaptive Speed Control Mode.
`'
`As is known, the operation of a Doppler radar system
`is dependent upon the presence of a relative velocity
`between two objects. The adaptive speed control
`system described herein simultaneously maintains a
`constant optimum spacing between two vehicles and
`also maintains the velocity of a trailing vehicle at the
`velocity of the leading vehicle. Accordingly, when the
`system has controlled the trailing car to the point that it
`is traveling at the same velocity as the lead vehicle,
`there is no Doppler signal present. In the absence of a
`provision for this difficulty, the car would then be con
`trolled either by the Automatic Speed Control System
`of the convenience type explained he'reinabove or by
`environmental parameters, such as hills, grades, wind,
`etc., which ordinarily affect the velocity. of a car. Ac
`cordingly, the car would then either accelerate or
`.decelerate with respect to thepreceding vehicle, caus
`ing the presence of a Doppler signal in the adaptive
`speed control system. This is an undesirable operation
`as the car would therefore bewhunting about the op
`timum speed and following distance, causing passenger
`
`35
`
`40
`
`45
`
`5.0
`
`55
`
`65
`
`pedal.
`
`'
`
`.
`
`.
`
`v
`
`_
`
`-
`
`,
`
`The car speed V2 is fed back to the E and 'Eq Signal
`Generator, so that the E and El, signals banlbe' ’
`generated in accordance with the range and rangelrate
`calculations. The E signal is fed to Speed ‘Adjust 32
`which actuates Throttle Actuator 34 through Speed
`Control Unit 33. This signal then actuates the throttle
`and changes the speed of the vehicle. It should be noted
`that the vehicle velocity change executed by Throttle
`Actuator 34 can either increase or’ decrease ‘the
`velocity of the car. In those instances in which some
`decrease of velocity is required but the decrease is not '
`so drastic as to require a braking action, the automobile
`accelerator is merely raised above its existing position
`so that the speed of the car decreases. v,In those in
`stances in which an increase in velocity ‘is required the
`accelerator is actuated in .the opposite direction ‘to
`cause an increase in the car speed.
`7
`"
`—
`When the information input to E and E1, Generator
`23 dictates that a braking action is required, ari'E,J
`signal is generated. This signal is smoothed and ain
`pli?ed in the Circuit 36 and then serves to actuate the
`Brake Actuator 37, which executes the braking func
`tion. A braking action is then applied to the vehicle in
`
`discomfort.
`
`I
`
`I
`
`v
`
`V
`
`This is avoided by providing the Adaptive Speed
`Control System with a memory circuit. When a Target
`
`MERCEDES
`EXHIBIT 1016
`
`

`
`7
`proportion to the value of the [5,, signal so that the car is
`slowed an amount sufficient for the assumption of the
`optimum following distance.
`A Speed Sensor 39, which is coupled to the
`speedometer of the vehicle, generates a signal which is
`proportional to the velocity of the controlled vehicle.
`This signal is input to Speed Control Unit 33 and used
`to generate the V2 voltage which is indicative of the
`vehicle speed.
`A Control Display Panel 38 receives inputs from the
`E and Eb Generator as well as Percent Brake and Per
`cent Throttle Signals from Brake Actuator 37 and
`Throttle Actuator 34, respectively. Control Panel 38
`can therefore include a visual indication so that the
`driver is aware of the operation of the system. For ex
`ample, an acceleration signal can be indicated by a
`green light, a deceleration signal by a red light, and a
`normal condition signal by a yellow light. The Percent
`Brake and Percent Throttle Signals can be used to
`change the intensity of the red and green lights, respec
`tively, and thereby indicate the amount of braking or
`acceleration which is occurring. Furthermore, Control
`And Display Panel 38 can include the On and Off
`Switch, the Accelerate, Decelerate, Memorize, and
`other controls which are necessary for inputs to the
`system.
`Although it is not apparent from the description of
`FIG. 2, the system has several very signi?cant ad
`vantages. In operating under the control of the speed
`control system, the driver selects the speed of the vehi
`cle. The adaptive speed control system cannot ac
`celerate the vehicle above this speed. Also, the adap
`tive speed control system, in some/instances, overrides
`the automatic speed control system. However, the re
`membered speed selected by the driver is not
`disturbed, so that automatic control is resumed at the
`remembered speed when the adaptive control ceases to
`function. These features
`are
`fully
`described
`hereinafter.
`As explained hereinabove, the inventive system has
`alternative modes of operation. The controlled vehicle
`is either brought to a safe following distance behind a
`lead vehicle or is maintained at a selected cruising
`speed when no lead vehicle is present. The steady safe
`following distance is governed by the speed of the lead
`vehicle. When the distance to the lead vehicle deviates
`from the desired range or when the two vehicles do not
`have the same velocity, appropriate commands are au
`tomatically sent to the throttle or brake so that the fol
`lowing vehicle assumes the speed of the lead vehicle
`and maintains the optimum following distance.
`The throttle and brake commands are represented by
`error signals, which are used to maintain the proper
`vehicle control and are based on a control law using
`two error functions, E and E,,. E is the accelerator error
`function which is used to control the vehicle by use of
`the accelerator pedal, and E1, is the brake error func
`tion which is used to decelerate the vehicle by use of
`the brakes. In order to properly utilize the error func
`tions, it is necessary to equate the variables of the
`system geometry into two usable equations which
`respectively de?ne the E and E,, functions.
`This was accomplished by the use of numerous
`hybrid computer simulations in which the various vari
`ables .of the system were changed and the optimum
`coefficients for the various parameters were de?ned.
`
`35
`
`45
`
`55
`
`65
`
`3,725,921
`
`8
`Accordingly, the Throttle and Brake Commands, E
`and El, respectively, are based on a control de?ned as
`follows:
`.
`
`5
`
`m.p.h.)
`
`'‘ (3)
`
`Where:
`E = The accelerator error function
`Eb = The brake error function
`R = Range of the lead car in feet
`R = Range-Rate between the two vehicles (positive if
`range is increasing and negative if range is decreas
`ing)
`R0 = Desired range
`V2 = Controlled car speed
`R0, the desired range, de?nes the following distance
`for a particular speed and, accordingly, is defined as:
`
`R0 = 55 + V2
`
`(4)
`
`Substituting equation (4) for the RI value of equa
`tion ( 1) yields:
`
`25
`
`The inventive system is designed to provide proper
`throttle and brake operation based on the E and E,,
`signals, respectively. The implementation of the Throt
`tle Command is described with respect to FIG. 3, and
`the implementation of the Brake Command is
`described with respect to FIG. 4. The E and E,, com
`mand functions are limited only by the capability of the
`automobile engine and braking capabilities.
`A block diagram of a preferred embodiment of a
`system for implementing the Throttle Command Func
`tion E is shown in FIG. 3. The system includes a
`Summing Ampli?er 41 which receives four inputs in
`dividually indicative of Range R, Range-Rate R, Car
`Speed V2, and a 55-foot offset. Reference to equation
`(1) hereinabove shows that these four parameters are
`those which define the Accelerator Error Function E. '
`Accordingly, the output of Summing Ampli?er 4-1.is
`the Accelerator Error Function E. The output of
`Summing Ampli?er 41 serves as an input to Memory
`Circuit 42.
`I
`Memory 42 is a circuit of well known type, for exam
`ple a charged capacitor, and is used in order to prevent
`noise from disturbing the E value when the Doppler
`signal is zero, which occurs when the two vehicles have
`zero relative velocity.
`The range input information which is derived from
`the Sensor System is fed to a Memory Circuit 43. The
`output of Memory Circuit 43 serves as the Range R
`input to Summing Ampli?er 41.‘
`Memory 43 receives an input from Timer 44 through
`a Resume Circuit 46 and also a direct input from Timer
`44. Timer 44 also receives a Target Absent input from
`the Sensor System.
`Memory 43, Timer 44, and Resume Circuit 46
`cooperate in a manner which enables the adaptive
`speed control system to maintain control of the vehicle
`even when the Doppler frequency is zero. This occurs
`when there is no relative velocity between the lead and
`following car. When there is a relative velocity between
`the two vehicles, a Doppler frequency exists and a
`
`MERCEDES
`EXHIBIT 1016
`
`

`
`9,
`_ Range Input is presented to Memory 43. In this condi
`tion, the Range Signal R serves as an input to Summing
`Circuit 41. When the Doppler frequency goes to zero,
`Timer 44 receives a Target Absent Input so that the
`timer switches Memory 43 to a memory mode so that
`the last Range Input is remembered. Accordingly, the
`Range Output R from Memory 43 remains constant for
`a preselected period of time determined by Timer 44.
`At the expiration of the time period, Timer 44 actuates
`Resume Circuit 43. The output of Resume Circuit 43
`actuates Memory 43 so that a very small voltage is
`added to the stored voltage which represents the re
`membered Range Input. This results in the appearance
`of a small range‘ increase and causes the vehicle to very
`slightly accelerate, resulting in a Doppler frequency.
`An input to Memory 43 is then available, and the car is
`under the control of the Adaptive Speed Control
`System. The voltage input to Memory 43 from Resume
`Circuit 46 is very small, so that a very slight accelera
`tion of the vehicle is realized. For this reason, the occu
`pants of the vehicle will be unaware of the acceleration
`and the change of velocity will be undetectable. The
`desired smooth, comfortable ride of the vehicle there
`fore is not disturbed by this operation of the system.
`The output of Timer 44 actuates a