Method and Apparatus for Performing Driving Assistance
The present invention relates to methods and apparatuses for performing driving assistance for a controlled vehicle, involving determining a longitudinal acceleration target value on the basis of a lateral acceleration of the controlled vehicle and one or more setting parameters, and controlling a longitudinal acceleration of the controlled vehicle on the basis of the calculated longitudinal acceleration target value. According to the invention, a lateral acceleration acting, during cornering, on a proceeding vehicle, which moves in the longitudinal direction on the road ahead of the controlled vehicle, is estimated, and the one or more setting parameters for the calculation of the longitudinal acceleration target value are set based on the estimated lateral acceleration acting on the proceeding vehicle during cornering.
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The present invention relates to a method and an apparatus for performing driving assistance for a vehicle.
BACKGROUNDIn the prior art of performing driving assistance for a vehicle, there are known the concepts of so-called Electronic Stability Control (ESC), also referred to as Electronic Stability Program (ESP) or Dynamic Stability Control (DSC), which is a computer-implemented control technology for improving the safety of a vehicle's stability by detecting and reducing loss of traction, wherein the control target is the yaw moment of the vehicle.
Other control concepts for performing driving assistance for a vehicle such as so-called cruise control (CC) and adaptive cruise control (ACC) are known. According to cruise control (CC), the longitudinal acceleration of a controlled vehicle is controlled based on a comparison of a user-set target speed and a current speed of the controlled vehicle. If the current speed is lower than the user-set target speed, the controlled vehicle will be positively accelerated until the current speed matches the user-set target speed, and if the current speed is larger than the user-set target speed, the controlled vehicle will be decelerated until the current speed matches the user-set target speed. According to adaptive cruise control (ACC), the vehicle will be controlled similar to the above-described cruise control (CC) but, in addition, as soon as and as long as it is determined that a distance to a proceeding vehicle is equal or lower than a user-set or pre-set target distance, the longitudinal acceleration of the controlled vehicle will be controlled such as to keep the target distance to the proceeding vehicle at least as long as the proceeding vehicle is traveling at a speed equal to or lower than the target speed.
Recently, according to EP 1 992 537 A2, another concept for performing driving assistance for a vehicle was proposed, which concept (referred to as e.g. G-Vectoring Control, GVC) can be provided alternatively or also additionally to the above-mentioned Electronic Stability Control (ESC), in which the control target is the longitudinal acceleration of the vehicle and the control is based on a lateral acceleration and lateral jerk of the vehicle. The longitudinal acceleration control concept of GVC may be extended as Preview G-Vectoring Control (PGVC) by using a predicted lateral acceleration and lateral jerk of the vehicle.
Specifically, according to a control concept, a lateral acceleration of the vehicle, which is an acceleration of the vehicle in a lateral direction perpendicular to a longitudinal direction of the vehicle corresponding to a moving direction of the vehicle, and a lateral jerk of the vehicle, which is a jerk of the vehicle in the lateral direction, are determined. Based on the determined lateral acceleration and lateral jerk, a longitudinal acceleration of the vehicle is controlled.
While the principle concept of control of longitudinal acceleration of the vehicle and the control on the basis of lateral jerk has been developed, it is desirable to modify and develop further the control concept of EP 1 992 537 A2 for providing improved safety and higher driver's comfort and convenience, and in particular for providing improved vehicle handling and cornering behavior.
SUMMARY OF THE INVENTIONIn view of the above object, there is proposed a method for performing driving assistance for a vehicle according to claim 1 and an apparatus for performing driving assistance for a vehicle according to claim 15 according to the present invention. Further, a computer program product according to claim 16 is proposed. Dependent claims relate to some of the preferred embodiments of the present invention.
According to a general aspect of the present invention, there may be provided a method or apparatus for performing driving assistance for a vehicle in which a lateral acceleration and a lateral jerk of the moving vehicle or at least parameters indicative of the lateral acceleration and the lateral jerk of the moving vehicle are determined, in particular regularly determined or even continuously monitored, and a longitudinal acceleration of the moving vehicle may then be controlled on the basis of the determined lateral acceleration and lateral jerk.
Also, in addition or as an alternative there may be provided a method or apparatus for performing driving assistance for a vehicle in which a lateral acceleration and a lateral jerk of the moving vehicle or at least parameters indicative of the lateral acceleration and the lateral jerk of the moving vehicle are predicted (estimated) in advance based on a vehicle speed of the controlled vehicle and on the basis of curvature information such as a curvature of a curve of the road ahead of the controlled vehicle, e.g. at a preview point, in particular regularly predicted (estimated) or even continuously predicted (estimated), and a longitudinal acceleration of the moving vehicle may then be controlled on the basis of the predicted (estimated) lateral acceleration and lateral jerk, e.g. on the basis of a time derivative of the curvature of a curve of the road ahead of the controlled vehicle and the vehicle speed of the controlled vehicle.
According to a first aspect of the invention, there is proposed a method for performing driving assistance for a controlled vehicle moving in a longitudinal direction on a road, comprising determining a longitudinal acceleration target value on the basis of a (determined and/or predicted/estimated) lateral acceleration of the controlled vehicle and one or more setting parameters, and controlling a longitudinal acceleration of the controlled vehicle on the basis of the calculated longitudinal acceleration target value.
According to the first aspect, the method may further comprise estimating or determining on a driving-character (driving characteristics) of a proceeding vehicle, which moves in the longitudinal direction on the road ahead of the controlled vehicle, and setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated or determined driving-character (driving characteristics) of the proceeding vehicle during cornering.
In preferred aspects, a driving characteristics of the proceeding vehicle may be determined or estimated on the basis of information received from the proceeding vehicle and/or from a data center which has information of the proceeding vehicle, using a communication protocol between the controlled vehicle and the proceeding vehicle and/or the data center. Preferably, a driving characteristics of the proceeding vehicle is estimated or determined on the basis of information detected by sensors from the controlled vehicle, a driving characteristics of the proceeding vehicle is estimated or determined based on the longitudinal acceleration and/or lateral acceleration acting on the proceeding vehicle, and/or a driving characteristics of the proceeding vehicle is estimated based on a predicted longitudinal acceleration and/or lateral acceleration, which will act on the proceeding vehicle.
It is to be noted that the information on a driving characteristics of the proceeding vehicle (which may indicate a speed, position, lateral acceleration, and/or longitudinal acceleration of the proceeding vehicle) may be obtained via data communications being established between the controlled vehicle and the proceeding vehicle and/or between a data center and the controlled vehicle, wherein the data sensor obtains the data from the proceeding vehicle or from other vehicle external sensors. In addition or alternatively, information on the driving characteristics may be obtained from sensor data e.g. from sensors of the controlled vehicle, which may detect a relative speed and relative position between the controlled vehicle and the proceeding vehicle. Then, speed, position and longitudinal acceleration of the proceeding vehicle may be determined based on speed and/or position of the controlled vehicle and relative speed and/or relative position between the controlled vehicle and the proceeding vehicle. Lateral acceleration of the proceeding vehicle may be estimated based on the estimated speed and position of the proceeding vehicle and based on curvature information indicating a curvature of a road at the position of the proceeding vehicle.
According to the first aspect, the method may comprise, in addition to or representing the step of estimating/determining the driving characteristics of the proceeding vehicle, estimating (e.g. predicting) or determining a lateral acceleration which is acting or will act, during cornering, on a proceeding vehicle, which moves in the longitudinal direction on the road ahead of the controlled vehicle, and setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated lateral acceleration which is acting or will act on the proceeding vehicle during cornering.
The present invention allows to advantageously increase the safety and driving convenience for the driver of the controlled vehicle in that the settings of the setting parameters of the longitudinal acceleration control are adjusted also depending on an estimated lateral acceleration of the proceeding vehicle, if any.
For example, controlling the longitudinal acceleration without any knowledge about the proceeding vehicle may disadvantageously lead to a situation in which the distance to the proceeding vehicle may reduce below a threshold during cornering. Then, the driver of the controlled vehicle may need to actively use a brake in addition to the longitudinal acceleration control operation in order to avoid reducing the distance to the proceeding vehicle further, or an adaptive cruise control may activate in order to reduce the speed of the controlled vehicle in order to avoid reducing the distance to the proceeding vehicle further, thereby reducing the driving convenience for the driver of the controlled vehicle.
However, according to the present invention, longitudinal acceleration control may be based on an estimated lateral acceleration acting on the proceedings vehicle by setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated lateral acceleration acting on the proceeding vehicle during cornering.
Especially, by adjusting the setting parameters such that longitudinal acceleration control based on the lateral acceleration of the controlled vehicle is adapted to the estimated lateral acceleration of the proceeding vehicle advantageously helps to avoid that the distance to the proceeding vehicle is reduced too much so that there is no necessity for the driver to actively decelerate by using the brake or that there is no necessity that the adaptive cruise control may activate.
Preferably, the method further comprises determining a speed of the proceeding vehicle, wherein the lateral acceleration acting on the proceeding vehicle is preferably estimated based on the determined speed of the proceeding vehicle and curvature information. This has the advantage that the lateral acceleration acting on the proceeding vehicle can be reliably and accurately estimated based on curvature information such as a curvature of the road ahead of the controlled vehicle as can be derived e.g. from map data (e.g. navigation map data). Preferably, the method may further comprise determining a position of the proceeding vehicle, and determining a curvature of the road at the position of the proceeding vehicle based on map data, wherein the lateral acceleration acting on the proceeding vehicle is preferably estimated based on the determined speed of the proceeding vehicle and the determined curvature of the road at the position of the proceeding vehicle.
According to the above aspect, it is preferable that the position of the proceeding vehicle is determined based on position data received from the proceeding vehicle; and/or the method may further comprise determining a position of the controlled vehicle, and determining a distance from the controlled vehicle to the proceeding vehicle (e.g. by means of a sensor such as radar, sonar, or light reflection etc.), wherein the position of the proceeding vehicle is preferably determined based on the position of the controlled vehicle and the determined distance to the proceeding vehicle.
According to another preferred aspect, the step of determining the longitudinal acceleration target value on the basis of a lateral acceleration of the controlled vehicle and one or more setting parameters is performed in one of a plurality of setting modes, wherein the one or more setting parameters may preferably be set differently in each of the plural setting modes preferably such that an average lateral acceleration and/or a maximum lateral acceleration acting on the controlled vehicle during cornering is different for each of the plural setting modes when being controlled based on the longitudinal acceleration control. Accordingly, possibly in accordance with driver's preferences, there may be provided setting modes providing less longitudinal deceleration during cornering (at the entrance of the curve) and/or higher positive acceleration at the exit of a curve than other setting modes.
In the above preferred aspect, it is further preferable that the plural setting modes comprise at least a first setting mode and a second setting mode, an average lateral acceleration and/or a maximum lateral acceleration acting on the controlled vehicle during cornering being larger in the second setting mode than in the first setting mode, wherein the step of setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated lateral acceleration acting on the proceeding vehicle during cornering preferably comprises selecting the first setting mode, if an absolute value of the estimated lateral acceleration acting on the proceeding vehicle is smaller than a threshold value, and/or selecting the second setting mode, if the absolute value of the estimated lateral acceleration acting on the proceeding vehicle is larger than the threshold value.
Accordingly, even if a driver of the controlled vehicle may have pre-selected the second setting mode as a default setting according to the driver's preferences, when it is determined that the estimated lateral acceleration acting on the proceeding vehicle during cornering may be less than the threshold, still the first setting mode will actually be selected for the longitudinal acceleration control, thereby leading to a lower average lateral acceleration and/or a maximum lateral acceleration acting on the controlled vehicle during cornering compared to the pre-set control behavior so that it can be efficiently and advantageously avoided that the distance to the proceeding vehicle reduces too much during cornering.
In further embodiments, the method may further comprise a step of determining which setting mode has been pre-set as a default setting according to the driver's preferences, i.e. whether the driver has pre-selected the first or second setting mode (or another setting mode). Preferably, the above selection of a setting mode can be performed further in dependence of the pre-set setting mode. For example, when the user has pre-set the first setting mode (or another setting mode in which the average lateral acceleration and/or the maximum lateral acceleration acting on the controlled vehicle during cornering is even lower than in the first setting mode), the second setting mode will preferably not be selected even in case the absolute value of the estimated lateral acceleration acting on the proceeding vehicle is larger than the threshold value. Instead, the pre-set setting mode is preferably maintained. Only in case the user has pre-set the second setting mode (or another higher setting mode in which the average lateral acceleration and/or the maximum lateral acceleration acting on the controlled vehicle during cornering is even higher than in the second setting mode), the second setting mode (or even a higher setting mode) is preferably selected in case the absolute value of the estimated lateral acceleration acting on the proceeding vehicle is larger than the threshold value.
Specifically, in the above preferred aspect, it is further preferable that the plural setting modes comprise at least a first setting mode and a second setting mode, an average lateral acceleration and/or a maximum lateral acceleration acting on the controlled vehicle during cornering being larger in the second setting mode than in the first setting mode, wherein the step of setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated lateral acceleration acting on the proceeding vehicle during cornering preferably comprises selecting the first setting mode if an absolute value of the estimated lateral acceleration acting on the proceeding vehicle is smaller than a threshold value (although the driver may have pre-selected the second setting mode), selecting the first setting mode if the absolute value of the estimated lateral acceleration acting on the proceeding vehicle is larger than the threshold value but the user has pre-selected the first setting mode, and/or selecting the second setting mode, if the absolute value of the estimated lateral acceleration acting on the proceeding vehicle is larger than the threshold value and the user has pre-selected the second setting mode.
In all of the above aspects, the position of the proceeding vehicle may be determined based on position data received from the proceeding vehicle and/or the speed of the proceeding vehicle may be determined based on speed data received from the proceeding vehicle. Also, lateral and/or longitudinal acceleration acting on the proceeding vehicle may be determined based on sensor data received from the proceeding vehicle. Alternatively, or in addition, the position of the proceeding vehicle may be determined based on a relative position of the proceeding vehicle detected by sensors from the controlled vehicle (e.g. based on sensed direction and/or distance to the proceeding vehicle, and/or the speed of the proceeding vehicle may be determined based on a relative speed to the controlled vehicle based on sensor data such as camera, sonar and/or radar.
According to another preferred aspect, the one or more setting parameters comprise at least one gain factor for control of negative longitudinal acceleration of the vehicle, wherein an absolute value of the longitudinal acceleration target value increases with increasing gain factor and decreases with decreasing gain factor. Preferably, the step of setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated lateral acceleration acting on the proceeding vehicle during cornering comprises setting the at least one gain factor for control of negative longitudinal acceleration of the vehicle based on a function of the estimated lateral acceleration acting on the proceeding vehicle during cornering. Preferably, the at least one gain factor for control of negative longitudinal acceleration of the vehicle as a function of the estimated lateral acceleration acting on the proceeding vehicle during cornering decreases with increasing absolute value of the estimated lateral acceleration acting on the proceeding vehicle during cornering.
Accordingly, during negative longitudinal acceleration control (deceleration control) of the controlled vehicle (e.g. at an entrance of a curve), the at least one gain factor will be determined on the basis of the function of the absolute value of the estimated lateral acceleration of the proceeding vehicle which decreases with increasing absolute value of the estimated lateral acceleration acting on the proceeding vehicle.
That is, when it is determined that the estimated lateral acceleration acting on the proceeding vehicle is lower, thereby indicating a lower cornering speed of the proceeding vehicle, the at least one gain factor will be set as a higher value, thereby leading to a stronger longitudinal deceleration of the controlled vehicle, and when it is determined that the estimated lateral acceleration acting on the proceeding vehicle is higher, thereby indicating a higher cornering speed of the proceeding vehicle, the at least one gain factor will be set as a lower value, thereby leading to a less strong longitudinal deceleration of the controlled vehicle.
Accordingly, it is efficiently, reliably and conveniently possible to perform the longitudinal acceleration control such that the distance to the proceeding vehicle does not easily decrease below a safety distance at which either the driver may need to actively decelerate or that an additionally provided adaptive cruise control may need to decelerate the vehicle at the expense of the driver's convenience and driving comfort.
According to another preferred aspect, the one or more setting parameters comprise at least one gain factor for control of positive longitudinal acceleration of the vehicle, wherein an absolute value of the longitudinal acceleration target value increases with increasing gain factor and decreases with decreasing gain factor. Preferably, the step of setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated lateral acceleration acting on the proceeding vehicle during cornering comprises setting the at least one gain factor for control of positive longitudinal acceleration of the vehicle based on a function of the estimated lateral acceleration acting on the proceeding vehicle during cornering, the at least one gain factor for control of positive longitudinal acceleration of the vehicle as a function of the estimated lateral acceleration acting on the proceeding vehicle during cornering increases with increasing absolute value of the estimated lateral acceleration acting on the proceeding vehicle during cornering.
Accordingly, during positive longitudinal acceleration control (positive acceleration control) of the controlled vehicle (e.g. at an exit of a curve), the at least one gain factor will be determined on the basis of the function of the absolute value of the estimated lateral acceleration of the proceeding vehicle which increases with increasing absolute value of the estimated lateral acceleration acting on the proceeding vehicle.
That is, when it is determined that the estimated lateral acceleration acting on the proceeding vehicle is lower, thereby indicating a lower cornering speed of the proceeding vehicle, the at least one gain factor will be set as a lower value, thereby leading to a less strong positive longitudinal acceleration of the controlled vehicle, and when it is determined that the estimated lateral acceleration acting on the proceeding vehicle is higher, thereby indicating a higher cornering speed of the proceeding vehicle, the at least one gain factor will be set as a higher value, thereby leading to a stronger positive longitudinal acceleration of the controlled vehicle.
Accordingly, it is efficiently, reliably and conveniently possible to perform the longitudinal acceleration control such that the distance to the proceeding vehicle does not easily decrease below a safety distance at which either the driver may need to actively decelerate or that an additionally provided adaptive cruise control may need to decelerate the vehicle at the expense of the driver's convenience and driving comfort.
According to another preferred aspect, determining the longitudinal acceleration target value may comprise determining a second longitudinal acceleration target value being calculated on the basis of a determined lateral acceleration and a corresponding lateral jerk of the vehicle during cornering.
According to another preferred aspect, which may be used alternatively or in addition to the above aspect, determining the longitudinal acceleration target value may comprise determining a third longitudinal acceleration target value being calculated on the basis of an estimated lateral acceleration of the vehicle at a preview point, which is preferably located ahead of the controlled vehicle at a predetermined preview distance or at a preview distance which preferably is calculated on the basis of a predetermined preview time and the current speed of the vehicle, the estimated lateral acceleration at a preview point being preferably calculated on the basis of an estimation of curvature of the road at the preview point and the current speed of the controlled vehicle.
In preferred aspects of the invention, the longitudinal acceleration target value is determined based on the second longitudinal acceleration target value and the third longitudinal acceleration target value.
According to a second aspect of the present invention, there is proposed an apparatus (such as a control unit or control system integrated in or mountable to a vehicle) for performing driving assistance for a controlled vehicle moving in a longitudinal direction on a road according to a method as described in any one of the preceding claims, comprising longitudinal acceleration target value determining means for determining a longitudinal acceleration target value on the basis of a lateral acceleration of the controlled vehicle and one or more setting parameters, and longitudinal acceleration control means for controlling a longitudinal acceleration of the controlled vehicle on the basis of the calculated longitudinal acceleration target value.
The apparatus may comprise driving characteristics determining means for estimating or determining driving characteristics of a proceeding vehicle, which moves in the longitudinal direction on the road ahead of the controlled vehicle, and setting means for setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated or predicted driving characteristics of the proceeding vehicle.
Specifically, there may be provided an apparatus (such as a control unit or control system integrated in or mountable to a vehicle) for performing driving assistance for a controlled vehicle moving in a longitudinal direction on a road according to a method as described in any one of the above first aspect and preferred aspects thereof. The apparatus may comprise longitudinal acceleration target value determining means for determining a longitudinal acceleration target value on the basis of a lateral acceleration of the controlled vehicle and one or more setting parameters, and longitudinal acceleration control means for controlling a longitudinal acceleration of the controlled vehicle on the basis of the calculated longitudinal acceleration target value. In addition, the apparatus may further comprise lateral acceleration estimation means for estimating a lateral acceleration acting, during cornering, on a proceeding vehicle, which moves in the longitudinal direction on the road ahead of the controlled vehicle, and setting means for setting the one or more setting parameters for the calculation of the longitudinal acceleration target value based on the estimated lateral acceleration acting on the proceeding vehicle during cornering.
According to a third aspect of the present invention, there is proposed program product comprising computer program means for causing a vehicle control apparatus to execute the steps of a method as described in any one of the above first aspect and preferred aspects thereof.
In the above, the term “acceleration” may refer to a derivative of speed (or velocity) with respect to time and the term jerk refers to a derivative of acceleration with respect to time, or to a second derivative of speed (or velocity) with respect to time. Typically, if not stated otherwise, the term “acceleration” as used in the present disclosure may include positive acceleration (i.e. increasing speed) as well as negative acceleration (i.e. deceleration or reducing speed).
A lateral direction of the vehicle can also be referred to as a direction of the pitch axis of the vehicle and a longitudinal direction of the vehicle can be referred to as a direction of the roll axis of the vehicle.
Moreover, while velocity, acceleration and jerk are in general vector quantities, terms such as lateral acceleration, longitudinal acceleration, and lateral jerk are typically referring to scalar quantities.
In a Cartesian coordinate system of the vehicle having the yaw, pitch and roll axes as principal axes of the coordinate system, a lateral acceleration refers to the pitch axis coordinate of the acceleration vector and a longitudinal acceleration refers to the roll axis coordinate of the acceleration vector. Similarly, a lateral jerk refers to the pitch axis coordinate of the jerk vector.
In the driving control, while the longitudinal acceleration may preferably need to discriminate between positive acceleration (acceleration of the vehicle in the sense of increasing speed) and negative acceleration (deceleration) of the vehicle in the sense of decreasing speed and/or braking, the lateral acceleration does not necessarily need to discriminate between positive lateral acceleration (i.e. acceleration towards the left/right) and negative lateral acceleration (i.e. acceleration towards the right/left) since driving control should preferably be performed similar for left turn and right turn driving.
Therefore, a lateral acceleration may similarly refer to the absolute value of the pitch axis coordinate of the acceleration vector, however, then a lateral jerk may preferably refer to the derivative of the absolute value of the lateral acceleration with respect to time. On the other hand, a lateral jerk preferably again may preferably need to discriminate between positive jerk (i.e. increasing lateral acceleration) and negative jerk (i.e. decreasing lateral acceleration).
Preferred embodiments of the present invention will be described below with reference to the accompanying figures. The described features and aspects of the embodiments may be modified or combined to form further embodiments of the present invention.
Longitudinal acceleration control for cornering (named Preview G-Vectoring Control: PGVC) is one of the driver assistance systems to reduce the driver's pedal works on the winding road driving. This system can decelerate/accelerate the vehicle automatically depend on the curvature of driving course. However it has no function to decelerate/accelerate the vehicle to keep the distance from a proceeding vehicle. Adaptive Cruise Control (ACC) is the function to keep the distance from a proceeding vehicle, and combination of PGVC and ACC would be one of the solutions to keep the distance from the proceeding vehicle during the cornering scenario. It is useful to deal these two functions independently from the view point of tuning/adding/replacing/reducing these functions. However, independent longitudinal acceleration controls by these different functions may change the longitudinal acceleration discontinuously, and it will give discomfort to a driver.
To avoid this discontinuous change of longitudinal acceleration, PGVC has an input signal from object detection device and changes the longitudinal acceleration control for cornering based on proceeding vehicle information (distance, speed). PGVC parameters are set to decelerate/accelerate the vehicle for cornering as the proceeding vehicle doing. For example, if the proceeding vehicle drives the curve slowly to reduce the lateral acceleration during cornering, ego vehicle also drives the curve slowly, even though the driver selected high-acceleration cornering setting. As the result, ego vehicle keeps the distance from the proceeding vehicle during cornering, and deceleration control by ACC to keep a safe time gap to proceeding vehicle would not be activated; longitudinal acceleration during cornering would be smooth.
The longitudinal acceleration Gx of the controlled vehicle is controlled by PGVC and ACC system. During driving on the straight road (
In this figure, the ego-vehicle may have lost the proceeding vehicle because of the limitation of obstacle detection device performance. However, even though the ego-vehicle keeps detecting the proceeding vehicle, ACC would decelerate the vehicle based on the distance between ego-vehicle and proceeding vehicle during cornering. This deceleration is controlled independently of longitudinal acceleration control for cornering and longitudinal acceleration does not change smoothly during cornering. This embodiment is proposed to solve this issue and provides the smooth longitudinal acceleration control for cornering with the proceeding vehicle.
In the below, first, the longitudinal-acceleration control for cornering is described. In order to extend the function of ACC to use in winding road driving, exemplarily, an additional longitudinal-acceleration control algorithm according to GVC or PGVC is proposed, using curvature information.
As the longitudinal-acceleration control based on a lateral motion, longitudinal-acceleration using lateral jerk called “G-Vectoring Control” (GVC) is available. As a fundamental equation defining GVC, the following equation can be used:
where Gxt
Specifically, based on sensor input by a sensor A or sensor system, which is configured to directly input a regularly or periodically determined or even continuously monitored lateral acceleration GY in the pitch axis direction of a vehicle to a control unit (controller) or indirectly provide sensor information on the basis of which the lateral acceleration GY can be estimated, a longitudinal acceleration control target value Gxt
The sensor A or sensor system may comprise acceleration sensitive sensors such as e.g. motion sensors, accelerometers and/or yaw-rate, pitch-rate and/or roll-rate sensitive gyro-sensors. In addition, or alternative, the sensor A may comprise a steering wheel (or driving wheel) angular sensor sensitive to a steering wheel angle (or driving wheel angle) and a lateral acceleration may be calculated on the basis of vehicle speed and the determined steering wheel angle (or driving wheel angle), and/or it may be estimated on the basis of pitch, roll and/or yaw rates determined by a gyro-sensor.
Based on the input lateral acceleration GY, a derivative of the lateral acceleration GY with respect to time is derived or calculated, referred to as lateral jerk Gy, and based on the lateral acceleration GY and the lateral jerk ĠY, the longitudinal acceleration target control value Gxt
Here, Cxy and T are auxiliary control parameters that can be pre-defined and stored in a memory unit of the control unit 1. Cxy is referred to as a “gain factor” (a dimensionless parameter), and the longitudinal acceleration target control value Gxt
According to equation (1) above, the sign of the longitudinal acceleration target control value Gxt
Here, the lateral acceleration GY may discriminate between left and right lateral direction by being negative for left (or right) sided lateral acceleration and correspondingly being positive for right (or left) sided lateral acceleration. On the other hand, lateral acceleration GY may also only refer to an absolute value of lateral acceleration, however, then the lateral jerk ĠY needs to refer to the derivative of the absolute value of lateral acceleration with respect to time.
Specifically, when a vehicle is entering a curve for cornering and the driver moves the steering wheel so that the vehicle turns about the yaw axis, lateral acceleration GY (which is zero on a straight road independent of whether the vehicle is accelerating, decelerating or moving at a constant speed) will start to increase from zero, see period between times t1 and t2 in
In an intermediate period between times t2 and t3 in
Here, depending on the topology of the curve, the time period between times t2 and t3 may be very short or not even exist. In the later case, the lateral acceleration GY may increase from zero to a maximum value and thereafter directly decrease again down to zero when leaving the curve.
As shown in
The longitudinal acceleration target control value Gxt
Consequently, directly after entering the curve and beginning the cornering in the first period between times t1 and t2, the longitudinal acceleration target control value Gxt
In the intermediate period between times t2 and t3, the longitudinal acceleration target control value Gxt
Finally, in the last stage of cornering before leaving the curve, during the period between times t3 and t4, the longitudinal acceleration target control value Gxt
According to the relations as explained with reference to
Summarizing the above, in the control of the longitudinal acceleration GX of the vehicle according to the longitudinal acceleration target control value Gxt
In addition to GVC as discussed above, as another longitudinal-acceleration control based on curvature, longitudinal-acceleration using longitudinal-acceleration model called “Preview G-Vectoring Control” (PGVC) is also available.
Gy
By assuming that acceleration/deceleration is executed with an equivalent algorithm to longitudinal-acceleration control in response to lateral motion of the vehicle (i.e., GVC), it is possible to control longitudinal-acceleration before lateral motion of the vehicle actually occurs. With GVC, on the basis of the above-mentioned assumption, longitudinal-accelerations corresponding to Gy_pv are calculated by using Gy_pv in place of the lateral jerk (ĠY) given by Equation (1). In this manner, a longitudinal-acceleration command value (Gxt_pv) related to the lateral motion of the vehicle that will be generated (rather than lateral motion of the vehicle that was generated) is given. Under the some assumptions (κ pv is positive, V is constant), Gxt_pv is given by Equation (3) from Equations (1), (2) using gain (Cxy_pv) and time constant (Tpv).
The longitudinal control of PGVC (Gxt_PGVC) is calculated based on the G-Vectoring Control command (Gxt
In
Desired acceleration during cornering strongly depends on a driver's taste: some driver likes high-acceleration cornering and some driver wants to turn without excessive acceleration. In response to the difference of the driver's preference, different settings of PGVC will be prepared by changing the PGVC parameters (mainly the gain Cxy, Cxy
Specifically, a driver input switch 230 may be adapted to allow a user to select parameter settings of the PGVC parameters which can be input as driver input information to the PGVC parameter setting block 110 embodying a setting means. On the other hand, vehicle dynamics information detection devices 210 (such as sensors including speed sensor, accelerometer, gyro-sensor, steering wheel angle sensor etc.) may provide information on the vehicle dynamics (vehicle dynamics information) such as vehicle speed, steering wheel angle, lateral and/or longitudinal acceleration acting on the controlled vehicle etc. The vehicle dynamics information is provided to the PGVC block 120 embodying a longitudinal acceleration target value determining means. In addition curvature information (such as map data and/or a curvature at a preview point determined based on map data) is provided from a curvature detection device 220 to the PGVC block 120 embodying the longitudinal acceleration target value determining means.
A PGVC controller 100 (e.g. a longitudinal acceleration control means) comprises the PGVC block 120 and the PGVC parameter setting block 110, and is adapted to output the target control value Gxt
Using these information, PGVC parameters are set to decelerate/accelerate the vehicle for cornering as the proceeding vehicle doing. For example, if the proceeding vehicle drives the curve slowly to reduce the lateral acceleration during cornering, ego vehicle also drives the curve slowly, even though the driver selected high-acceleration cornering setting like setting 4 in
In this case, driver selects the setting 4 at the beginning. During the driving on the straight road (
Features, components and specific details of the structures of the above-described embodiments may be exchanged or combined to form further embodiments optimized for the respective application. As far as those modifications are readily apparent for an expert skilled in the art they shall be disclosed implicitly by the above description without specifying explicitly every possible combination, for the sake of conciseness of the present description.
Claims
1. Method for performing driving assistance for a controlled vehicle moving in a longitudinal direction on a road, comprising:
- determining a longitudinal acceleration target value (GXT—PGVC) on the basis of a lateral acceleration (GY; GY—PV) of the controlled vehicle and one or more setting parameters (CXY; TS; CXY—PV; TS—PV), and
- controlling a longitudinal acceleration (GX) of the controlled vehicle on the basis of the calculated longitudinal acceleration target value (GXT—PGVC),
- wherein
- estimating or determining a driving characteristics of a proceeding vehicle which moves in the longitudinal direction on the road ahead of the controlled vehicle, and
- setting the one or more setting parameters (CXY; TS; CXY—PV; TS—PV) for the calculation of the longitudinal acceleration target value (GXT—PGVC) based on the estimated or predicted driving characteristics of the proceeding vehicle.
2. Method according to claim 1, wherein
- a driving characteristics of the proceeding vehicle is estimated or determined on the basis of information received from the proceeding vehicle or from a data center which has information of the proceeding vehicle, using a communication protocol between the controlled vehicle and the proceeding vehicle or the data center,
- a driving characteristics of the proceeding vehicle is estimated or determined on the basis of information detected by sensors of the controlled vehicle,
- a driving characteristics of the proceeding vehicle is estimated or determined based on the longitudinal acceleration and/or lateral acceleration acting on the proceeding vehicle, and/or
- a driving characteristics of the proceeding vehicle is estimated based on a predicted longitudinal acceleration and/or lateral acceleration, which will act on the proceeding vehicle.
3. Method according to claim 1, wherein
- estimating or determining a driving characteristics of the proceeding vehicle comprises estimating or determining a lateral acceleration (GY—EST—PV) and/or longitudinal acceleration acting, during cornering, on the proceeding vehicle, and
- wherein the one or more setting parameters (CXY; TS; CXY—PV, TS—PV) for the calculation of the longitudinal acceleration target value (GXT—PGVC) are set based on the estimated or determined lateral acceleration (GY—EST—PV) and/or the estimated or determined longitudinal acceleration acting on the proceeding vehicle during cornering.
4. Method according to claim 2, wherein
- determining a speed of the proceeding vehicle,
- wherein the lateral acceleration (GY—EST—PV) acting on the proceeding vehicle is estimated based on the determined speed of the proceeding vehicle and curvature information.
5. Method according to claim 2, wherein
- determining a position of the proceeding vehicle, and
- determining a curvature of the road at the position of the proceeding vehicle based on map data,
- wherein the lateral acceleration (GY—EST—PV) acting on the proceeding vehicle is estimated based on the determined speed of the proceeding vehicle and the determined curvature of the road at the position of the proceeding vehicle.
6. Method according to claim 5, wherein
- the position of the proceeding vehicle is determined based on position data received from the proceeding vehicle.
7. Method according to claim 5, wherein
- determining a position of the controlled vehicle, and
- determining a distance from the controlled vehicle to the proceeding vehicle,
- wherein the position of the proceeding vehicle is determined based on the position of the controlled vehicle and the determined distance to the proceeding vehicle.
8. Method according to claim 1, wherein
- determining the longitudinal acceleration target value (GXT—PGVC) on the basis of a lateral acceleration (GY; GY—PV) of the controlled vehicle and one or more setting parameters (CXY; TS; CXY—PV; TS—PV) is performed in one of a plurality of setting modes,
- wherein the one or more setting parameters are set differently in each of the plural setting modes such that an average lateral acceleration and/or a maximum lateral acceleration acting on the controlled vehicle during cornering is different for each of the plural setting modes.
9. Method according to claim 8, wherein
- the plural setting modes comprise at least a first setting mode (setting 1; setting 2; setting 3) and a second setting mode (setting 2; setting 3; setting 4), an average lateral acceleration and/or a maximum lateral acceleration acting on the controlled vehicle during cornering being larger in the second setting mode than in the first setting mode,
- wherein setting the one or more setting parameters (CXY; TS; CXY—PV; TS—PV) for the calculation of the longitudinal acceleration target value (GXT—PGVC) based on the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering comprises selecting the first setting mode (setting 1; setting 2; setting 3), if an absolute value of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle is smaller than a threshold value (Gy1; Gy2; Gy3), and selecting the second setting mode (setting 2; setting 3; setting 4), if the absolute value of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle is larger than the threshold value (Gy1; Gy2; Gy3).
10. Method according to claim 1, wherein
- the one or more setting parameters comprise at least one gain factor (CXY—PV—D; CXY—D) for control of negative longitudinal acceleration of the vehicle, wherein an absolute value of the longitudinal acceleration target value (GXT—PGVC) increases with increasing gain factor (CXY—PV—D; CXY—D) and decreases with decreasing gain factor (CXY—PV—D; CXY—D), and
- wherein setting the one or more setting parameters (CXY; TS; CXY—PV, TS—PV) for the calculation of the longitudinal acceleration target value (GXT—PGVC) based on the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering comprises setting the at least one gain factor (CXY—PV—D; CXY—D) for control of negative longitudinal acceleration of the vehicle based on a function of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering, wherein the at least one gain factor (CXY—PV—D; CXY—D) for control of negative longitudinal acceleration of the vehicle as a function of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering decreases with increasing absolute value of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering.
11. Method according to claim 1, wherein
- the one or more setting parameters comprise at least one gain factor (CXY—PV—A; CXY—A) for control of positive longitudinal acceleration of the vehicle, wherein an absolute value of the longitudinal acceleration target value (GXT—PGVC) increases with increasing gain factor (CXY—PV—A; CXY—A) and decreases with decreasing gain factor (CXY—PV—A; CXY—A), and
- wherein setting the one or more setting parameters (CXY; TS; CXY—PV; TS—PV) for the calculation of the longitudinal acceleration target value (GXT—PGVC) based on the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering comprises setting the at least one gain factor (CXY—PV—A; CXY—A) for control of positive longitudinal acceleration of the vehicle based on a function of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering, wherein the at least one gain factor (CXY—PV—A; CXY—A) for control of positive longitudinal acceleration of the vehicle as a function of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering increases with increasing absolute value of the estimated lateral acceleration (GY—EST—PV) acting on the proceeding vehicle during cornering.
12. Method according to claim 1, wherein
- determining the longitudinal acceleration target value (GXT—PGVC) comprises determining a second longitudinal acceleration target value (GXT—GVC) being calculated on the basis of a determined lateral acceleration (GY) and a corresponding lateral jerk (ĠY) of the vehicle during cornering.
13. Method according to claim 1, wherein
- determining the longitudinal acceleration target value (GXT—PGVC) comprises determining a third longitudinal acceleration target value (GXT—PV) being calculated on the basis of an estimated lateral acceleration (GY—PV) of the vehicle at a preview point, which is located ahead of the controlled vehicle at a predetermined preview distance (Lpv) or at a preview distance (Lpv) which is calculated on the basis of a predetermined preview time (tpv) and the current speed of the vehicle, the estimated lateral acceleration (Gy—est) at a preview point being calculated on the basis of an estimation of curvature of the road at the preview point and the current speed of the controlled vehicle.
14. Method according to claim 12, wherein
- the longitudinal acceleration target value (GXT—PGVC) is determined based on the second longitudinal acceleration target value (GXT—GVC) and the third longitudinal acceleration target value (GXT—PV).
15. Apparatus for performing driving assistance for a controlled vehicle moving in a longitudinal direction on a road according to the method as described in claim 1, comprising:
- longitudinal acceleration target value determining means (120) for determining a longitudinal acceleration target value (GXT—PGVC) on the basis of a lateral acceleration (GY; GY—PV) of the controlled vehicle and one or more setting parameters (CXY; TS; CXY—PV; TS—PV), and
- longitudinal acceleration control means (100) for controlling a longitudinal acceleration (GX) of the controlled vehicle on the basis of the calculated longitudinal acceleration target value (GXT—PGVC),
- wherein
- driving characteristics determining means (240) for estimating or determining driving characteristics of a proceeding vehicle, which moves in the longitudinal direction on the road ahead of the controlled vehicle, and
- setting means (110) for setting the one or more setting parameters (CXY; TS; CXY—PV; TS—PV) for the calculation of the longitudinal acceleration target value (GXT—PGVC) based on the estimated or predicted driving characteristics of the proceeding vehicle.
16. Computer program product comprising computer program means for causing a vehicle control apparatus to execute the steps of a method according to claim 1.
Type: Application
Filed: Jan 30, 2014
Publication Date: Apr 2, 2015
Applicant: Hitachi, Ltd. (Tokyo)
Inventors: Junya TAKAHASHI (Munich), Heiko ALTMANNSHOFER (Tann), Makoto YAMAKADO (Tokyo), Atsushi YOKOYAMA (Tokyo)
Application Number: 14/168,304
International Classification: B60W 30/18 (20060101); G05D 13/02 (20060101);