Abstract:
For regulating the speed of a motor vehicle, a control apparatus is equipped with an object detection system, and the reference speed is determined as a function of at least one preceding vehicle in the evaluation region of the object detection system, such that upon recognition of an imminent lane change by the regulated vehicle, vehicles in the adjacent destination lane are additionally taken into consideration for calculation of the reference speed by expanding the evaluation region in the direction of the destination lane, and consideration is given only to vehicles in the destination lane whose distance from the regulated vehicle is less than a predetermined distance value.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method and an apparatus for regulating the speed of a motor vehicle, the apparatus being equipped with an object detection system, and in which the reference speed is determined as a function of at least one preceding vehicle in the evaluation region of the object detection system. 
         [0003]    2. Description of Related Art 
         [0004]    Published German patent document DE 196 37 245 discloses a method and an apparatus for regulating the speed of a vehicle in consideration of preceding vehicles. In order to select a preceding vehicle as a regulation target, a future driving path profile is determined. In the context of an intended and/or incipient lane change by the regulated vehicle, the determined future driving path is widened. 
         [0005]    As a result, in the context of an intended lane change, vehicles in the lane alongside are also taken into consideration; incorrect reactions by the speed regulator often occur because consideration is given to vehicles in the adjacent lane that, however, result in incorrect reactions because of their great distance from the regulated vehicle, which reactions are not comprehensible to, and therefore inconvenient for, the driver. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention relates to a method and an apparatus for regulating the speed of a motor vehicle, the apparatus being equipped with an object detection system, and in which the reference speed is determined as a function of at least one preceding vehicle in the evaluation region of the object detection system, such that upon recognition of an imminent lane change by the regulated vehicle, vehicles in the adjacent destination lane are additionally taken into consideration for calculation of the reference speed by expanding the evaluation region in the direction of the destination lane, and consideration being given only to vehicles in the destination lane whose distance from the regulated vehicle is less than a predetermined distance value. Provision can additionally be made that the evaluation region on the side opposite the destination lane is reduced during the lane change. 
         [0007]    What is meant in the context of the present invention by the term “destination lane” is the adjacent lane into which the regulated vehicle would like to change by way of a lane change action. In the context of the disclosure of the present invention, an explanation has been given here, by way of example, of a lane change of a vehicle from a center lane M to a right lane R of a three-lane road. This disclosure is, however, explained only by way of example. What is of course meant in the context of the invention is any lane change from an arbitrary lane to another arbitrary lane adjacent on the left or right side, the indications “left,” “right,” and “center” to be correspondingly modified here as applicable. 
         [0008]    The essence of the present invention is to describe a method and an apparatus such that only those vehicles in the adjacent lane that are relevant to the planned lane change are sensed. 
         [0009]    For this purpose, advantageously, upon recognition of a lane change intention, the evaluation region of the object detection sensor is expanded beyond the own lane toward the destination lane, although only those vehicles in the adjacent lane whose distance is below a certain distance value are taken into consideration. As a result, vehicles far away in the adjacent destination lane are not considered, so that erroneous and undesired controller behavior can be avoided. 
         [0010]    Advantageously, the evaluation region is dimensioned substantially so that it senses the lane currently being traveled in. 
         [0011]    It is additionally advantageous that the predetermined distance value is a predefined value, with the result that the function is easily implemented and the controller behavior with respect to distance is always comprehensible, or else the predetermined distance value is a modifiable value, with the result that the controller behavior can be adapted to the particular contextual situation in each lane change situation, and the method becomes particularly convenient as a result of this adaptiveness. For example, the predetermined modifiable distance value can be accomplished as a function of the speed of the own (regulated) vehicle, or else can be configured as a function of the relative speed of the detected vehicle in the destination vehicle lane with respect to the regulated own vehicle. 
         [0012]    It is additionally advantageous that the evaluation region is reduced, during the lane change, on the side opposite the destination lane. The influence of vehicles that are located in the adjacent lane opposite the destination lane is thereby reduced; this can be relevant in particular when the vehicle in the adjacent lane that is opposite the destination lane wishes to change to what is at present the own lane. In addition, preceding vehicles in the own lane are given less-dominant consideration because a portion of the own lane is no longer covered by the reduced evaluation region, with the result that the controller behavior is determined even more by vehicles in the destination lane, and the driving behavior of a human driver is even more strongly simulated. It is particularly advantageous in this context that the reduction of the evaluation region on the side opposite the destination lane occurs only within the distance region within which the evaluation region on the destination-lane side is expanded. 
         [0013]    It is additionally advantageous that recognition of an imminent lane change by the regulated vehicle is accomplished by evaluation of a lane change recognition device. The lane change recognition device can be, for example, coupled to the directional indicator, so that when the driver actuates the turn-signal lever and the directional indicator is activated, the system according to the present invention registers an imminent lane change. It is additionally possible to recognize the imminent lane change intention by way of a yaw rate signal, by ascertaining the rotation angle of the vehicle about its vertical axis and recognizing, from the time derivative of said rotation angle, that the own vehicle is moving toward a adjacent lane. Systems of this kind are already present in most modern vehicles by way of vehicle-dynamics control systems, so that this reliable signal is usable in particularly advantageous fashion. A further possibility for recognizing an imminent lane change consists in evaluating a steering wheel angle signal, a rotation angle sensor being installed, for example, in the steering column of the steering wheel and detecting a motion of the steering wheel that can result in a lane change. 
         [0014]    It is additionally advantageous that the expansion of the evaluation region on the destination-lane side and/or the reduction of the evaluation region on the side opposite the destination-lane side are canceled after a predetermined time period has elapsed, the time period usually being dimensioned such that an average lane change can be carried out in that time. Alternatively, it is advantageous that the expansion of the evaluation region on the destination-lane side and/or the reduction of the evaluation region on the side opposite the destination-lane side are canceled when the end of the lane change operation by the regulated vehicle is recognized by evaluation of the lane change signal of a lane change recognition means. Once again, the directional indicator, a yaw rate sensor, and/or a steering wheel angle sensor are advantageously provided as a lane change recognition means. 
         [0015]    Implementation of the method according to the present invention in the form of a control element that is provided for a control unit of an adaptive separation and speed control system of a motor vehicle is of particular importance. A program that is executable on a computing device, in particular on a microprocessor or signal processor, and is suitable for carrying out the method according to the present invention, is stored in the control element. In this case the invention is therefore implemented by a program stored on the control element, so that said control element equipped with the program represents the invention in the same way as the method for whose performance the program is suitable. An electrical storage medium, for example a read-only memory, can be used in particular as a control element. 
         [0016]    Further features, possible applications, and advantages of the invention are evident from the description below of exemplifying embodiments of the invention which are depicted in the Figures of the drawings. All features described or depicted, individually or in any combination, constitute the subject matter of the invention, regardless of their grouping in the Claims or their internal references, and regardless of their formulation or depiction in the description and the drawings, respectively. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic block diagram of an embodiment of the apparatus according to the present invention. 
           [0018]      FIG. 2  is a schematic plan view of the detection region of the system according to the present invention. 
           [0019]      FIG. 3  is a plan view of the detection region of the system according to the present invention, with an expanded evaluation region. 
           [0020]      FIG. 4  is a schematic plan view of the detection region of the system according to the present invention, with an expanded evaluation region and a reduced evaluation region. 
           [0021]      FIG. 5  is a flow chart of the method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]      FIG. 1  shows an adaptive separation controller  1  that possesses an input circuit  2  by way of which input signals  4 ,  6 ,  8 ,  10  are deliverable to adaptive separation controller  1 . The input signals  4  provided are signals of an object detection sensor  3  that can be configured, for example, as a lidar sensor, a radar sensor, a video sensor, or an ultrasonic sensor. The configuration as a radar sensor is particularly advantageous, the separation as well as the relative speed and azimuth angle of the detected objects being forwarded in this case from radar sensor  3  to input circuit  2 . Also delivered to input circuit  2  are input signals  6  that derive from a driver-actuable operating element. Provided as a driver-actuable operating element  5  is, for example, a steering column lever or buttons on the steering wheel with which the driver can put adaptive separation controller  1  into operation, switch it off, and modify operating parameters of separation controller  1 . Also delivered to input circuit  2  of adaptive separation controller  1  is an input signal  8  that derives from a vehicle speed sensor  7 . Vehicle speed sensor  7  makes available a signal that represents the speed of regulated vehicle  18  and that is delivered to adaptive separation controller  1  so that the relative speed of the objects recognized by way of object detection sensor  3  can be converted into absolute speeds, and so that speed-dependent functions can be controlled. Also provided is a lane change recognition device  9  with which a lane change signal  10  is outputtable to input circuit  2 . Lane change recognition means  9  is embodied, for example, as a directional indicator switch, so that when the driver actuates the turn-signal lever, adaptive separation and speed controller  1  is informed that the driver is planning a lane change. It is additionally possible to embody lane change recognition device  9  as a yaw rate sensor, which measures the rotation angle of the vehicle about its vertical axis and can recognize a lane change based on the derivative over time of the yaw rate angle. Alternatively, a steering wheel angle sensor that can recognize, from the steering wheel actuation, an intention to change lanes, can be provided as a lane change recognition device. This lane change recognition signal  10  can, for example, indicate to adaptive separation controller  1  whether a lane change is intended and, if a lane change is intended, the direction in which it is to be expected and, if applicable, when said lane change operation has been completed. 
         [0023]    Input signals  4 ,  6 ,  8 ,  10  delivered to adaptive separation controller  1  by way of input circuit  2  are forwarded by way of a data exchange device  11  to a calculation device  12 , where output signals are ascertained from the input signals using the method according to the present invention. The output signals ascertained in calculation device  12  are forwarded via data exchange device  11  to an output circuit  13  that in turn makes output signals  14 ,  16  available. Output signal  14  is an acceleration signal that is outputted to a power-determining positioning element  15  of an internal combustion engine and can be embodied, for example, as an acceleration request or as a torque request. This acceleration signal is converted by power-determining positioning element  15 , which can be embodied e.g. as an electrically controllable throttle valve or as an electrically controllable fuel quantity metering device in the form of a fuel injection valve of a reservoir injection system, into a vehicle acceleration. Also outputted by output circuit  13  is a deceleration signal  16  that is connected to a deceleration device  17  of the vehicle. The deceleration signal is outputted as a deceleration request, as a brake pressure request, or as a braking force request, and is forwarded by a braking force amplifier to the wheel brakes of the vehicle, which in turn convert the deceleration signal into a vehicle deceleration. According to the present invention, in the case in which a planned lane change is recognized by way of lane change recognition device  9 , this is reported to adaptive separation controller  1  whereupon, in calculation device  12 , the evaluation region of the objects recognized by object detection sensor  3  is modified in such a way that the evaluation region is expanded in the direction of the destination lane. As a result, the controller reaction to vehicles in the adjacent destination lane can already be implemented early on, thereby regulating the vehicle in the context of a lane change without sudden accelerations or decelerations. 
         [0024]      FIG. 2  schematically depicts the evaluation region of object detection system  3  when driving straight ahead. Regulated vehicle  18 , which is equipped at the front of the vehicle with an object detection sensor  3 , is visible. In the case in which it is equipped as a radar sensor, object detection sensor  3  can emit microwave radiation and receive the partial radiation reflected from objects within the detection region, and recognize the separation and relative speed of the detected objects. A coordinate system dx, dy is described for this purpose with respect to object detection sensor  3 , coordinate axis dx being oriented in the direction of the extended vehicle longitudinal axis, and coordinate axis dy being oriented in the lateral direction with respect to the direction of travel. Provided inside the object detection region is an evaluation region  20  that substantially encompasses the region of the lane presently being traveled in, and thus has a typical width of dyL to dyR, the separation between dyL and dyR typically corresponding to one lane width. This evaluation region  20  is delimited laterally, in the region of the lane delimiters, by lateral evaluation region boundaries  19 . The provision of this evaluation region means that only those detected objects that are located within this region are evaluated, but not objects that are located outside evaluation region  20 . For example, if regulated vehicle  18  is traveling in center lane M of a three-lane road, then by way of example, only center lane M is evaluated by way of evaluation region  20  with regard to relevant objects. Objects that are located to the left or right of lane M that is presently being traveled in, i.e. objects having lateral offsets of dy&lt;dyL, as well as objects that are located next to evaluation region  20  to the right, i.e. with lateral offsets dy&gt;dyR, are consequently located in the adjacent left lane L or the adjacent right lane R, and are not taken into consideration for determination of the reference speed of regulated vehicle  18 . As a result of the provision of this above-described evaluation region  20 , objects in adjacent lanes are not evaluated, so that slower objects in neighboring lanes, or stationary objects at the side of the road, have no influence on the reference speed of adaptive separation controller  1 . 
         [0025]    If, when driving with adaptive separation controller  1  activated, an imminent lane change is recognized by lane change recognition device  9 , the relevant evaluation region is modified within calculation device  12 . For this purpose, as described in  FIG. 3 , evaluation region  20  is expanded on the side corresponding to the destination lane. In the case of a lane change to the right, the destination lane is the adjacent right lane, and in the case of an intended lane change to the left, the adjacent left lane is the destination lane. In the example depicted, lane change recognition device  9  recognizes a lane change to the right by the fact that, for example, the directional indicator is actuated to the right by the driver, or a corresponding steering wheel motion has been detected, or a corresponding yaw-rate signal has been identified. In this case an expanded evaluation region  21 , which evaluates a region in the neighboring lane to the right, is provided on the side of the destination lane, i.e. in the region of lane R. The width of expanded evaluation region  21  is dimensioned so that it likewise typically provides one lane width, so that the right-hand boundary of expanded evaluation region  21  (DY=DYRneu) corresponds to three times half the lane width DYR. According to the present invention, expanded evaluation region  21  is evaluated only out to a certain distance dx, since objects located farther away in the destination lane need not be taken into consideration for regulation at present. Two evaluation region parameters dx 1  and dx 2  are thus provided, such that expanded evaluation region  21 , beginning at dx=dx 1 , narrows to normal width; and at distance dx 2 , evaluation region  20  reaches lateral boundaries  19  of evaluation region  20  when driving straight ahead, as described in  FIG. 2 . Evaluation region parameters dx 1  and dx 2  can be predefined distance values, but optionally it is also possible to modify these distance values dx 1  and dx 2  as a function of the present vehicle speed V that is identified by vehicle speed sensor  7 , or as a function of the relative speed Vrel that is identifiable by way of object detection sensor  3 . For example, at higher speeds V the length of expanded evaluation region  21  can be shifted toward greater distances dx. As a result of expansion  21  (depicted in  FIG. 3 ) of evaluation region  20  in the distance region from dx=0 to distance values dx=dx 1  or dx=dx 2 , consideration is given only to those vehicles in the destination lane that are occupying a distance region relevant for regulation of the reference speed. 
         [0026]      FIG. 4  depicts a further embodiment according to the present invention that improves the regulation behavior of adaptive separation controller  1  when a lane change has been recognized. Regulated vehicle  18  is once more visible, with object detection sensor  3 , which monitors the region in front of the vehicle with regard to relevant objects, mounted on the front side. If what is recognized is, as in the present case, a lane change to the right into lane R, then not only are objects sensed within the region of lane M that is presently being traveled in, i.e. objects having a lateral offset of dyL&lt;dy&lt;dyR, but additionally also objects in the adjacent right lane that have a lateral offset of dyR&lt;dy&lt;dyRneu, this expanded evaluation region  21  being utilized for regulation only out to distance values dx=dx 1  or dx=dx 2 . To ensure that vehicles that are located in the adjacent left lane L and may be driving too close to center lane M, or that are intending to make a lane change from lane L to lane M, are not taken into consideration in the determination of the reference speed of regulated vehicle  18  (since otherwise undesired controller reactions might occur that the driver may perceive as disruptive and in some cases as hazardous), left boundary  19  of evaluation region  20  can be no longer positioned at dy=dyL as previously, but can instead be shifted so that evaluation region  20  is delimited by boundary  22 , resulting in a reduction of the lateral evaluation region  20  on the side opposite destination lane R. This is done by modifying evaluation boundary  19  on the left side toward quantitatively smaller dy values, so that the new lateral evaluation region boundary  22  that is opposite the destination lane side moves farther toward the center of lane M that is presently being traveled in. 
         [0027]      FIG. 5  depicts a flow chart of the method according to the present invention. The flow chart begins in step S 24  at “Start”; step S 24  can be followed by a step S 32  “End” that can optionally be present. The following step S 25  checks whether adaptive separation and speed controller  1  is active or deactivated. If ACC system  1  is switched off, S 25  branches to No and execution waits for the activation of adaptive separation controller  1 . If adaptive separation and speed controller  1  is active, step S 25  then branches to Yes, and step S 26  queries whether a lane change is imminent. Input signals  10  of lane change recognition device  9  are evaluated for this purpose. If this evaluation indicates that a lane change is not imminent, step S 26  branches again to No and the method waits until a lane change has been recognized by lane change recognition device  9 . Upon recognition of an intent to change lanes, the method branches to Yes in step S 26 , and in step S 27  the evaluation region  20 , which covers center lane M, is expanded to the destination lane in accordance with expanded evaluation region  21 . Optionally, in the following step S 28 , provision can additionally or alternatively be made that evaluation region  20  on the side opposite the destination lane, i.e. the adjacent left lane L, is narrowed by decreasing left boundary  19  of evaluation region  20  from dy=dyL to dy=dyLneu. At this stage, for the duration of the lane change, what is processed is the modified evaluation region, in which vehicles in the destination lane are utilized to ascertain the reference speed of regulated vehicle  18 , and any objects at the left edge of lane M that is presently being traveled in, i.e. between left boundaries  19  and  22  of the evaluation region, are no longer taken into consideration for ascertaining the reference speed of the regulated vehicle. If it is found in the next step S 29  by way of lane change recognition device  9  that the lane change is not yet complete, or in the case in which a predetermined time period for the lane change has not yet elapsed, step S 29  then branches to No and the modified evaluation region (in accordance with the preceding steps S 27  and S 28 ) is maintained. If step S 29  recognizes that the lane change is complete or that the time period that was provided for the lane change has elapsed, step S 29  then branches to Yes, and in the following step S 30  the expanded evaluation region  21  is narrowed back down to the lane width presently being traveled in, so that objects having a lateral offset of dy&gt;dyR are no longer evaluated for regulation purposes. If the optional or alternative step S 28  was provided, then the optional or alternative step S 31  is also necessary; this provides that the evaluation region narrowed to dy=dyLneu is reset back to the old dimension, by setting the left boundary of evaluation region  20  back to the lateral offset dy=dyL. Once the original evaluation region  20  has been reestablished in accordance with steps S 30  and/or S 31 , and regulated vehicle  18  is once again traveling straight ahead with no intention to change lanes, the method according to the present invention is terminated at step S 32  and can be resumed again, upon recognition of a new lane change, with step S 26 .