Control device and method for improving fuel efficiency in a CACC system

Abstract

Disclosed herein is a control device and method for improving fuel efficiency in a CACC system. This device and method can improve fuel efficiency by controlling vehicle speed so that, if a vehicle using the CACC system senses a preceding vehicle and enters a CACC activation mode, the vehicle is driven using an optimized cost, taking into account a target vehicle speed, a current vehicle speed, a minimum driving speed set in the vehicle, and a deceleration distance. The control method for improving fuel efficiency in a CACC system includes setting a target speed profile based on a target speed and an expected driving path of a subject vehicle, determining whether there is a target vehicle that the subject vehicle is to follow, and controlling the driving speed of the subject vehicle according to the set target speed profile based on the presence of the target vehicle.

Description

[0001] This application is a divisional application. The application number of the parent application is 2017108323391, the application date is September 15, 2017, and the name of the invention is “Control device and method for improving fuel efficiency in CACC system”. Technical Field

[0002] An exemplary embodiment of the present invention relates to a control device and method for improving fuel efficiency in a cooperative adaptive cruise control (CACC) active mode in a CACC system, and more specifically, to a control device and method for improving fuel efficiency in a CACC active mode, which can improve fuel efficiency by controlling the vehicle speed so that the vehicle travels using optimized cost taking into account the target vehicle speed set in the vehicle, the current speed of the vehicle, the minimum driving speed, and the deceleration distance if the vehicle using the CACC system senses a vehicle ahead and enters the CACC active mode. Background Art

[0003] An Adaptive Cruise Control (ACC) system operates to perform automated driving at a speed equal to or lower than a speed set by the driver, while maintaining a predetermined distance from a target vehicle. The ACC system provides functionality for maintaining a sufficient distance to prevent a collision with a target vehicle ahead, acquired through distance and / or position measurement sensors installed on the vehicle or a cruise function for automated driving at a user-set speed.

[0004] The ACC system enables the driver to adjust the vehicle's driving speed without continuously operating the accelerator pedal to provide convenience to the driver, and can achieve safe driving by maintaining a predetermined distance from a target vehicle and preventing the vehicle from traveling at a speed exceeding a set speed.

[0005] Meanwhile, the CACC system enhances ACC functionality by adding V2X (Vehicle to Everything) communication to the aforementioned ACC system. The CACC system receives information about road speed limits via V2I (Vehicle to Infrastructure) and other vehicles traveling in the same lane via V2V (Vehicle to Vehicle), and uses this information to enhance ACC performance.

[0006] In recent years, in association with a driving route setting system such as navigation in a vehicle, a CACC system may set and use a target speed profile to improve fuel efficiency in consideration of road information on the driving route.

[0007] Generally, a CACC system operates by avoiding a collision with a target vehicle by driving according to a set target speed profile when the target vehicle is not present. If the target vehicle is detected or a preceding vehicle is connected to the CACC system, the system decelerates to maintain a predetermined distance from the target vehicle. However, if the target vehicle is detected and braking is performed to maintain a predetermined distance, driving is performed using a target speed profile different from the initially set target speed profile, and the vehicle's speed is adjusted based on the target vehicle's speed. Consequently, rigid control, with frequent acceleration and deceleration, may be implemented, reducing fuel efficiency. Summary of the Invention

[0008] An object of the present invention is to provide a control device and method for improving fuel efficiency in a cooperative adaptive cruise control (CACC) system, which can control the current speed of a subject vehicle when a target vehicle is present, and can set a new target speed curve with an optimized cost based on the current speed, wherein the current speed changes according to the target vehicle in the CACC system, which is based on V2X (Vehicle to Everything) communication and radar.

[0009] Other purposes and advantages of the present invention can be understood through the following description and become apparent with reference to the embodiments of the present invention. In addition, it will be apparent to those skilled in the art that the purposes and advantages of the present invention can be achieved by the claimed means and combinations thereof.

[0010] According to one aspect of the present invention, a collaborative adaptive cruise control (hereinafter referred to as "CACC") system provided in a subject vehicle for controlling the driving speed of the subject vehicle includes: a communication unit configured to receive vehicle information, the vehicle information including the position and driving information of adjacent vehicles; an information collection unit configured to collect driving information of a leading vehicle and vehicle information of the subject vehicle using sensors provided on the subject vehicle; and a control unit configured to select a target vehicle to be followed by the subject vehicle based on the vehicle information of the adjacent vehicles acquired by the communication unit and the driving information of the leading vehicle collected by the information collection unit, and to control the driving speed of the subject vehicle based on the target speed of the subject vehicle if no target vehicle to be followed by the subject vehicle is selected, and to control the driving speed of the subject vehicle based on the speed information of the target vehicle, the speed information of the subject vehicle and the target time interval if a target vehicle to be followed by the subject vehicle is selected.

[0011] The CACC system according to aspects of the present invention may further include a drive unit configured to control a throttle and a brake, wherein the control unit controls the drive unit to control the driving speed of the subject vehicle. Furthermore, the CACC system according to aspects of the present invention may further include a driver vehicle interface (DVI) unit configured to receive a target speed and / or target time interval input from a driver and to notify the driver of status information of the CACC system.

[0012] The control unit may include: a state management unit configured to manage the state of the CACC system; a target vehicle selection unit configured to select a target vehicle to be followed by the subject vehicle based on vehicle information of an adjacent vehicle acquired from the communication unit and driving information of a preceding vehicle collected by the information collection unit; a curve management unit configured to set a target speed curve based on a target speed and an expected driving path of the subject vehicle if there is no target vehicle selected by the target vehicle selection unit, and to set a target speed curve based on speed information of the target vehicle, speed information of the subject vehicle, and an expected driving path if there is a target vehicle selected by the target vehicle selection unit; and a driving management unit configured to control the driving speed of the subject vehicle according to the set target speed curve.

[0013] The status management unit can display the status of the CACC system as one of an off state in which the CACC system does not work, a standby state in which the CACC system is working but does not control the driving speed of the subject vehicle, an ACC activated state in which the driving speed of the subject vehicle is controlled only using information obtained from the subject vehicle in a state in which no vehicle exists in an area of interest connected by V2V communication, and a collaborative activated state in which the driving speed of the subject vehicle is controlled using information from the adjacent vehicles obtained by V2V communication and information obtained from the subject vehicle in an area of interest connected by V2V communication.

[0014] If there is a possibility of collision when the driving speed of the subject vehicle is controlled according to the set target speed curve, the driving management unit may request the curve management unit to set a new target speed curve, and the curve management unit may be reset based on the speed information of the target vehicle, the speed information of the subject vehicle and the expected path information according to the request for the new target speed curve setting from the driving management unit.

[0015] According to another aspect of the present invention, a control method for improving fuel efficiency in a cooperative adaptive cruise control (hereinafter referred to as "CACC") system provided in a subject vehicle for controlling the driving speed of the subject vehicle includes: determining whether to start the CACC system operation; setting a target speed curve based on the target speed and expected driving path of the subject vehicle; determining whether there is a target vehicle that the subject vehicle is to follow; as a result of the determination, if there is no target vehicle, controlling the driving speed of the subject vehicle according to the set target speed curve; as a result of the determination, if there is a target vehicle, comparing the minimum distance Ds that can prevent the subject vehicle from colliding with the target vehicle even if it is traveling according to the target speed curve with the current distance Dc to the target vehicle; and as a result of the comparison, if the current distance Dc is greater than the minimum distance Ds, controlling the driving speed of the subject vehicle according to the target speed curve, and performing fuel-efficient driving if the current distance Dc is less than the minimum distance Ds.

[0016] Here, fuel-efficient driving can be performed by considering a driving cost Cc in the case of driving while maintaining the decelerated current speed after deceleration so that the minimum distance Ds becomes less than the current distance Dc, a driving cost Ccontrol in the case of driving according to a new target speed curve generated based on the decelerated current speed, the speed of the target vehicle, the speed of the subject vehicle, the minimum driving speed set in the subject vehicle, the distance required to reach the target vehicle speed Vtarget by the auxiliary deceleration device, and a distance margin according to the deceleration method.

[0017] Performing fuel-efficient driving may include comparing a driving cost Cc in a case of current constant-speed driving such that a minimum distance Ds becomes less than a current distance Dc after deceleration of the subject vehicle with a driving cost Ccontrol in a case of driving according to a new target speed curve generated based on the decelerated current speed; as a result of the comparison, if the driving cost Cc is less than the driving cost Ccontrol, maintaining the constant-speed driving at the current speed of the subject vehicle or performing deceleration by comparing the current speed of the subject vehicle with the speed of a target vehicle; and as a result of the comparison, if the driving cost Cc is greater than the driving cost Ccontrol, comparing the current speed of the subject vehicle with a minimum speed set in the subject vehicle, wherein comparing the current speed of the subject vehicle with the minimum speed set in the subject vehicle includes, if the current speed of the subject vehicle is higher than the minimum speed set in the subject vehicle, performing deceleration driving by an auxiliary deceleration device; and if the current speed of the subject vehicle is lower than the minimum speed set in the subject vehicle, performing driving at the minimum speed set in the subject vehicle.

[0018] Maintaining constant speed driving at the current speed of the subject vehicle or performing deceleration by comparing the current speed of the subject vehicle with the speed of the target vehicle may further include, if the current speed of the subject vehicle is lower than the speed of the target vehicle, performing driving at the current speed of the subject vehicle; and if the current speed of the subject vehicle is greater than the speed of the target vehicle, comparing the current distance Dc2 between the subject vehicle and the target vehicle with the sum of the distance Dcruise required to reach the driving speed of the target vehicle by the auxiliary deceleration device and the distance margin M1 according to the auxiliary deceleration device.

[0019] Comparing the current distance Dc2 with the sum of the distance Dcruise and the distance margin M1 may include traveling at the current vehicle speed if the current distance Dc2 is greater than the sum of the distance Dcruise and the distance margin M1; and comparing the current distance Dc2 with the sum of the distance Dbrake required to reach the target vehicle's driving speed by performing braking through the brake and the distance margin M2 required during braking by the brake if the current distance Dc2 is less than the sum of the distance Dcruise and the distance margin M1.

[0020] Comparing the current distance Dc2 with the sum of the distance Dbrake and the distance margin M2 may include performing deceleration by an auxiliary deceleration device of the vehicle if the current distance Dc2 is greater than the sum of the distance Dbrake and the distance margin M2; and performing deceleration by braking if the current distance Dc2 is less than the sum of the distance Dbrake and the distance margin M2.

[0021] The target speed profile may be set in consideration of road information regarding a travel path of the vehicle, and the road information may include road curvature, grade, and turning radius.

[0022] The following effects can be achieved according to the configurations and combinations thereof and the usage relationship therebetween according to the embodiments of the present invention as described above.

[0023] When the CACC system is executed, fuel efficiency can be improved by following a new target speed profile without collision even in the presence of a target vehicle.

[0024] Furthermore, since there is no need to artificially perform continuous deceleration according to the distance to the target vehicle, an additional advantage can be provided on the side of fuel efficiency.

[0025] Furthermore, while ensuring a sufficient distance to prevent a collision with a target vehicle, the system is configured to follow a new driving method according to the vehicle's current speed, and thus can optimize driving costs.

[0026] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0028] Figure 1 A schematic diagram of a CACC system according to the present invention;

[0029] Figure 2 Schematic diagram showing the region of interest (ROI) of the CACC system on a straight road;

[0030] Figure 3 A block diagram illustrating a configuration of a CACC system according to an embodiment of the present invention;

[0031] Figure 4 A schematic diagram illustrating state transitions of a CACC system according to an embodiment of the present invention;

[0032] Figure 5 A schematic diagram illustrating a target speed curve generated by the curve management unit 337 according to a target speed setting of a driver and a driving speed of a target vehicle according to an embodiment of the present invention;

[0033] Figure 6 Schematic diagram showing a new target speed curve set by the curve management unit 337 according to the driving speed of the target vehicle;

[0034] Figure 7 A schematic diagram illustrating an example of setting a new target speed profile after deceleration to maintain a preset minimum vehicle distance or minimum time interval according to an embodiment of the present invention;

[0035] Figure 8 A schematic diagram illustrating an example of a driving speed of a subject vehicle according to an inter-vehicle distance and the cost magnitudes of Cc and Ccontrol according to the present invention;

[0036] Figure 9 A schematic diagram illustrating a change in the inter-vehicle distance between a subject vehicle and a target vehicle when the subject vehicle is traveling at a constant speed higher than that of the target vehicle according to an embodiment of the present invention;

[0037] Figure 10 is a schematic diagram showing the distance relationship between Dcruise, Dbrake, M1 and M2;

[0038] Figure 11 is a flowchart of a control method for improving the fuel efficiency of a CACC system using a target speed profile if a target vehicle exists according to an embodiment of the present invention; and

[0039] Figure 12 is a flowchart illustrating a control method for performing fuel-efficient driving according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to clearly illustrate the present invention, parts irrelevant to the description are omitted. In the entire description of the present invention, the same or similar elements in various drawings are marked with the same reference numerals.

[0041] Throughout the description of the present invention, the terms "connected to" or "coupled to" used to indicate connection or coupling of one element to another element include both the case where an element is "directly connected to or coupled to" another element and the case where an element is connected or coupled to another element via another element. The term "comprising" used in this specification means that in addition to the components described, one or more other components are not excluded.

[0042] The term "on" used to indicate that an element is on another element includes both the case where the element is directly on the other element and the case where the element is located on the other element via the other element. In contrast, the term "directly on" means that the element is directly on another element without the intervention of any other element.

[0043] Although the terms "first, second, etc." are used to describe different elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish an element, component, region, layer, or section from other elements, components, regions, layers, or sections. Therefore, in the following description, a first element, a first component, a first region, a first layer, or a first section may be different from or the same as a second element, a second component, a second region, a second layer, or a second section without departing from the scope of the present invention.

[0044] In the following description of the present invention, the terms used are used to illustrate the embodiments of the present invention, but do not limit the scope of the present invention. In this description, unless otherwise specified, singular expressions may include plural expressions. The term "comprising" as used in the specification means that in addition to the presence or addition of the described features, regions, wholes, steps, operations, elements and / or parts, one or more other features, regions, wholes, steps, operations, elements and / or parts are not excluded.

[0045] Spatially relative terms such as "below," "beneath," "lower," "above," and "above" as shown in the figures may be used to facilitate description of the relationship between an element or constituent element and another element or other constituent elements. Spatially relative terms should be understood to include different orientations of the elements during use or operation in addition to the orientation shown in the drawings. For example, if the elements shown in the figures are described oppositely, an element described as being "below" or "beneath" another element may be placed "above" the other element. Thus, the exemplary term "below" may include two orientations corresponding to "below" and "above." Elements may be rotated 90° or at another angle, and the spatially relative terms may be interpreted accordingly.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used as the meanings commonly understood by those skilled in the art to which the present invention belongs. In addition, terms that are commonly used but not defined in dictionaries should not be ideally or excessively explained unless they have been clearly and unambiguously defined.

[0047] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Matters defined in this specification, such as detailed configurations and elements, are merely specific details provided to assist those skilled in the art in fully understanding the present invention. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms.

[0048] First, terms that may be used in the specification will be defined.

[0049] Front vehicle: A vehicle that is in front of the subject vehicle and moving along the same road and in the same direction as the subject vehicle

[0050] Clearance: The distance between the rear of the vehicle ahead and the head of the subject vehicle

[0051] Region of interest: An area in which potential vehicles of interest and target vehicles described later exist and which may have an impact on the control of the CACC system provided in the subject vehicle

[0052] Potential vehicles of interest: Vehicles that are present in the area of interest and are in V2V communication with the subject vehicle

[0053] Target vehicle: A vehicle that follows the subject vehicle and may or may not be connected to the subject vehicle via V2V communication

[0054] Time interval: A value calculated based on the speed of the subject vehicle and the distance between the subject vehicle and the vehicle ahead (time interval = distance / speed)

[0055] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0056] Figure 1 Schematic diagram of the CACC system to which the present invention is applied.

[0057] like Figure 1 As shown, the CACC system 300 applied to the present invention is a system in which wireless communication with the vehicle ahead and / or infrastructure is added to enhance the sensing capability of the ACC system of the prior art. The CACC system 300 can use V2I communication to receive road speed limits, time intervals (the time difference between the subject vehicle and the vehicle ahead), and / or other standard messages from roadside equipment (RSE). That is, the CACC system 300 of the vehicle can receive input of information (such as recommended set speeds or time intervals) from the regional traffic control system through V2I communication. In addition, the CACC system can receive adjacent vehicle information including driving information (speed and acceleration) of the adjacent vehicle 20 through V2V communication with at least one adjacent vehicle 20, or can transmit its own vehicle information to the adjacent vehicle 20. In addition, the CACC system can use sensors in the prior art to obtain vehicle information of vehicles that may be ahead of the subject vehicle.

[0058] In this case, the traveling vehicle information may include a vehicle identification (ID) for distinguishing from other vehicles, vehicle shape, size, braking performance, vehicle financial resource information including gross vehicle weight, vehicle position information indicated by 3D coordinates of latitude, longitude and altitude, vehicle approach angle measured based on true north, vehicle speed, acceleration, yaw rate, braking status, throttle position and steering angle.

[0059] Furthermore, the CACC system can receive input from the driver regarding a set speed or time interval via a driver vehicle interface (DVI) 60, and can notify the driver of the status information of the CACC system. Furthermore, the CACC system can obtain vehicle information 50 from various sensors or control devices provided within the vehicle. Based on the various data collected through the above-described methods, the CACC system can control the vehicle's speed by controlling the throttle or brakes.

[0060] As described above, by acquiring information through V2V and / or V2I communication, the CACC system can more accurately control the time interval with the vehicle ahead while maintaining a smooth ride and can respond very quickly to speed changes of multiple vehicles ahead. Furthermore, the CACC system offers the advantage of being able to set shorter time intervals without compromising safety or the driver's sense of stability.

[0061] Figure 2 Schematic diagram showing the region of interest (ROI) of the CACC system on a straight road.

[0062] The CACC system may only be interested in neighboring vehicles that enter a region of interest (ROI). Information from vehicles outside the ROI may be nearly meaningless for controlling the vehicle. Therefore, the CACC system may only use information from vehicles within the ROI to perform control operations, reducing the load applied to the CACC system.

[0063] refer to Figure 2 The ROI can be set to 16m and 32m in length in the left and right directions, respectively, based on the center of the vehicle equipped with the CACC system. Furthermore, the ROI can be set to 250m in front of the driver's seat and 100m in the rear. For curved roads, the ROI can be curved to match the curvature of the straight road.

[0064] In addition, the CACC system can set a target vehicle and a potential vehicle of interest (PVOI). A target vehicle refers to a vehicle in front that is followed by a subject vehicle on which the CACC system is installed. That is, when calculating a time interval, the CACC system uses the distance maintained between the subject vehicle and the target vehicle, and the target vehicle becomes a target for which the time interval is continuously maintained. A potential vehicle of interest refers to a vehicle that is within an area of interest and is connected to the CACC system through V2V communication. A potential vehicle of interest may be a vehicle that may affect the speed control of a subject vehicle on which the CACC system is installed. A vehicle that is in a side lane and is expected to join the lane of the subject vehicle, or a vehicle that is in the same lane as the subject vehicle and the target vehicle and is in front of the target vehicle may be a potential vehicle of interest, and the potential vehicle of interest may become a target vehicle.

[0065] Figure 3 is a block diagram showing the configuration of a CACC system according to an embodiment of the present invention.

[0066] refer to Figure 3 The CACC system according to the present invention may include an information collection unit 310, a communication unit 320, a DVI unit 340, and a control unit 330. The control unit 330 may include a state management unit 331, a driving management unit 333, and a target vehicle selection unit 335, and may further include a curve management unit 337.

[0067] The communication unit 320 can receive road speed limits, time intervals (the time difference between the subject vehicle and the preceding vehicle), and / or other standard messages from the RSE 10 via V2I communication. In other words, the vehicle's CACC system 300 can not only receive recommended set speeds or time intervals from the regional traffic control system via V2I communication, but also receive information related to roads, traffic, weather, and daily life. Furthermore, the communication unit 320 can receive neighboring vehicle information, including the driving information (speed and acceleration) of the neighboring vehicle 20, through V2V communication with at least one neighboring vehicle 20, or transmit its own vehicle information to the neighboring vehicle 20. Specifically, in this case, the communication unit can provide the neighboring vehicle 20 with not only its own driving information but also identification information or driving information of the preceding vehicle. If the neighboring vehicle only provides identification information, the communication unit can use the information from the neighboring vehicle with identification information to obtain vehicle information of the vehicle preceding the neighboring vehicle that has transmitted the identification information. Thus, the subject vehicle can obtain vehicle information even relative to the target vehicle and the vehicle preceding the target vehicle. On the other hand, when only identification information is transmitted, the amount of data transmitted by each vehicle can be reduced.

[0068] Furthermore, the information collection unit 310 can collect surrounding environment information collected using sensors, as well as subject vehicle information required for controlling the CACC system. Subject vehicle information can include the subject vehicle's speed, throttle, and brake control information, and surrounding environment information can include information collected by sensors about neighboring vehicles 20. Specifically, if a target vehicle is in front of the subject vehicle, the information collection unit can collect surrounding environment information by calculating the distance and speed of the target vehicle using radar or lidar.

[0069] DVI unit 340 can receive setting information input by the driver via the driver-vehicle interface and can transmit information to the driver that needs to be notified, such as status information of CACC system 300 and warning information that may be generated by CACC system 300. As an example, the driver can input a target speed and / or target time interval via DVI unit 340, and CACC system 300 can operate the subject vehicle to match the input target speed and / or target time interval. As another example described later, DVI unit 340 can also be used to inform the driver of status information regarding whether the CACC system is in an off state, a standby state, or an active state.

[0070] In addition, the CACC system may further include a drive unit (not shown). The drive unit may control a throttle valve and / or a brake according to a control signal of a control unit 330 described later.

[0071] Control unit 330 can control the driving speed of the subject vehicle based on the information acquired by information collection unit 310 and communication unit 320. Specifically, control unit 330 can select a target vehicle for the subject vehicle to follow based on the vehicle information of adjacent vehicles acquired by communication unit 320 and the driving information of the preceding vehicle acquired by information collection unit 310. If no target vehicle has been selected, control unit 330 can control the driving speed of the subject vehicle based on the target speed of the subject vehicle. If a target vehicle has been selected, control unit 330 can control the driving speed of the subject vehicle based on the speed information of the target vehicle, the speed information of the subject vehicle, and a target time interval. In this case, the user can set the target speed and target time interval, or the CACC system can automatically set the target speed and target time interval to suit the situation based on the information acquired by information collection unit 310 and communication unit 320.

[0072] In order to perform the above functions, the control unit 330 may include a state management unit 331 , a driving management unit 333 , a target vehicle selection unit 335 and / or a curve management unit 337 .

[0073] The target vehicle selection unit 335 can select a potential vehicle of interest and a target vehicle based on the vehicle information of multiple neighboring vehicles 20 obtained by the communication unit 320. A potential vehicle of interest refers to a neighboring vehicle that is present in the area of interest as described above. If a neighboring vehicle is within the area of interest based on the position information received from the neighboring vehicle and the position information of the subject vehicle, the corresponding neighboring vehicle can be selected and registered as a potential vehicle of interest. In addition, a preceding vehicle that is directly in front of the target vehicle among the potential vehicles of interest can be selected as the target vehicle. Specifically, in the case of a target vehicle, it is necessary to verify the target vehicle with very high reliability, and therefore the target vehicle can be selected by verifying the following three conditions based on the preceding vehicle information collected by the information collection unit 310.

[0074] 1. Using the position information of potential vehicles of interest, select potential vehicles of interest traveling in the same lane as the subject vehicle (hereinafter referred to as the "first group of potential vehicles of interest").

[0075] 2. Potential vehicles of interest (hereinafter referred to as the "second group of potential vehicles of interest") are selected, wherein the presence range information received from each potential vehicle of interest in the first group of potential vehicles of interest is within a value (0.1×(range measured by the sensor)) and (0.7×(length of each potential vehicle of interest)) greater than the other values. In this case, if the length of the potential vehicle of interest is unknown, the value (0.7×(length of each potential vehicle of interest)) may be 3.3 m.

[0076] 3. Potentially interesting vehicles (hereinafter referred to as "third group of potentially interesting vehicles") are selected, wherein the speed information received from each potential interesting vehicle of the second group of potentially interesting vehicles is within 1 m / s of the speed measured by the sensor.

[0077] Typically, only one potential vehicle of interest is included in the third group of potential vehicles of interest selected by verifying the three conditions. However, if the third group of potential vehicles of interest includes two or more potential vehicles of interest, the closest potential vehicle of interest may be selected as the target vehicle based on the position information of each of the third group of potential vehicles of interest.

[0078] If the presence / absence of a target vehicle or a vehicle of potential interest is determined by the target vehicle selection unit 335 , such information may be transmitted to the state management unit 331 , the driving management unit 333 , and / or the curve management unit 337 for the purpose of matching respective functions.

[0079] The state management unit 331 can manage the state of the CACC system. The CACC system can be in an off state, a standby state, or an active state depending on the state of the subject vehicle and the presence / absence of target vehicles and / or potential vehicles of interest.

[0080] Figure 4 Schematic diagram showing state transitions of a CACC system according to an embodiment of the present invention.

[0081] refer to Figure 4 The CACC system may include an off state 400 in which the CACC system is not operating, a standby state 500 in which the CACC system is operating but not controlling the driving speed of the subject vehicle, and an active state 600 in which the driving speed of the subject vehicle is controlled. Specifically, the active state 600 may include an ACC active state 610 in which the driving speed of the subject vehicle is controlled using only information obtained from the subject vehicle in a state where there are no vehicles connected via V2V communication in the area of interest, and a cooperative active state 620 in which a neighboring vehicle connected via V2V communication exists in the area of interest, and the driving speed of the subject vehicle is controlled using information from the neighboring vehicle obtained via V2V communication and information obtained from the subject vehicle.

[0082] The CACC system is not in operation in the off state 400. That is, the CACC system is not in operation in the off state 400. The CACC system can be switched to the off state 400 by stalling the vehicle or by manual operation of the driver.

[0083] Standby state 500 is a state in which the CACC system waits to be activated. In standby state 500, the CACC system does not perform speed control. If the subject vehicle is started, the CACC system may transition to standby state 500 after automatically completing self-diagnosis in off state 400. Alternatively, the CACC system may transition from off state 400 to standby state 500 through manual operation by the driver. Furthermore, if a manual control input (such as brake or throttle control) from the driver is received in active state 600, the CACC system may transition to standby state 500.

[0084] The activation state 600 is a state in which the CACC system is activated to perform speed control. As described above, the activation state 600 may include the ACC activation state 610 and the cooperative activation state 620. If there is no potential vehicle of interest or target vehicle connected via V2V communication, the CACC system operates in the ACC activation state 610, and if there is a potential vehicle of interest or target vehicle connected via V2V communication, the CACC system operates in the cooperative activation state 620. If the speed of the subject vehicle becomes higher than a predetermined speed (hereinafter referred to as "first speed") while the CACC system is in the standby state 500, it may transition to the activation state 600. In addition, if the speed of the subject vehicle decreases below the first speed in the activation state 600, the CACC system may prohibit acceleration or may transition to the standby state 500.

[0085] When the CACC system transitions to the active state 600, it may first operate in the ACC active state 610. In the ACC active state 610, cruise control may be performed to match the maximum speed set by the ACC system in the prior art, or subsequent control may be performed if there is a vehicle ahead. In the ACC active state 610, if there is a potential vehicle of interest or a target vehicle connected through V2V communication, and the data received from the potential vehicle of interest or the target vehicle is reasonable, the CACC system may transition to the cooperative active state 620. In an embodiment of the present invention, if the relevant information of the potential vehicle of interest or the target vehicle received using V2V communication is consistent with the vehicle information acquired by the sensor of the subject vehicle through the information collecting unit 310, it may be verified that the data is reasonable. This verification may be performed by the target vehicle selection unit 335.

[0086] Furthermore, the CACC system may transition to the ACC active state 610 if no potential vehicle of interest or target vehicle exists in the cooperative active state 620 , and may transition to the ACC active state 610 even if no V2V communication is performed or only unreasonable data is received.

[0087] The cooperative activation state 620 of the CACC system may include a non-following mode 621, a following mode 622, and a following mode 623. The non-following mode 621 is a mode executed when a potential vehicle of interest is connected through V2V communication but there is no target vehicle, and speed control of the subject vehicle by the CACC system may be affected by data received from the potential vehicle of interest.

[0088] Following mode 622 is a mode executed in the presence of a target vehicle connected through V2V communication, and in this case, speed control of the subject vehicle by the CACC system may be affected by information from the connected target vehicle and potential vehicles of interest.

[0089] Following mode 623 is a mode executed when a target vehicle is present but not connected via V2V communication. In this case, the target vehicle may be sensed by sensors of the subject vehicle, and this information may be acquired by information collection unit 310. In this case, speed control of the subject vehicle by the CACC system may be influenced by sensor-sensed information from the connected potential vehicle of interest and the target vehicle.

[0090] In the cooperative activation state 620 , the CACC system may operate in one of the three modes described above, and the three modes may be determined based on whether a target vehicle exists and whether the target vehicle is connected via V2V communication.

[0091] That is, reference Figure 4 In the cooperative activation state 620, if there is no target vehicle in the area of interest but there is a potential vehicle of interest, the CACC system may transition (A) to a non-following mode 621, and if there is a target vehicle connected via V2V communication, the CACC system may transition (B) to a following mode. If there is a target vehicle in the area of interest that is not connected via V2V communication and there is also a potential vehicle of interest in the area of interest, the CACC system may transition (C) to a following mode 623.

[0092] If there is neither a connected target vehicle nor a potential vehicle of interest, the CACC system may transition to the ACC active state 610 .

[0093] The maximum and minimum requirements for each mode controllable in the active state 600 of the CACC system may be defined as shown in Table 1 below.

[0094] [Form 1]

[0095]

[0096]

[0097] Referring to Table 1, the CACC system cannot set the minimum time interval to 0.5s or less, cannot perform deceleration control of 5m / s^2 or more by controlling the maximum brake, and cannot perform acceleration control of 2.75m / s^2 or more by controlling the throttle.

[0098] Reference again Figure 3 The state management unit 331 can manage the state of the CACC system 300 according to the above method. If the CACC system 300 is in the active state, the driving management unit 333 can control the driving speed of the subject vehicle. In the case of the CACC system 300, the driving speed is generally controlled so that the driver can drive to match the set target speed. However, if a target vehicle is present, the driving speed can be controlled so that the subject vehicle can follow the target vehicle.

[0099] According to the present invention, the driver can set a target speed profile that maximizes fuel efficiency based on the set target speed, and the driving management unit 333 can manage the driving speed of the subject vehicle according to the set target speed profile. In other words, the driving management unit 333 can control the driving speed of the subject vehicle by controlling auxiliary deceleration devices including the throttle, brake, and fuel cutoff.

[0100] In this case, the target speed profile used may be set by the profile management unit 337. However, if a target vehicle is present ahead and following control is performed, traveling according to the set target speed profile may not be possible, and in this case, a new target speed profile needs to be generated to maximize fuel efficiency.

[0101] Figure 5 FIG. 1 is a schematic diagram illustrating a target speed curve generated by the curve management unit 337 according to a target speed setting of a driver and a driving speed of a target vehicle according to an embodiment of the present invention.

[0102] refer to Figure 5 If the driver sets a target speed Vset, the curve management unit 337 can calculate the target speed curve V by integrating road information that can be obtained based on the set target speed Vset with respect to the future driving path. old_calc(t) for improving or maximizing fuel efficiency. The curve management unit 337 can collect map information and navigation information stored in the subject vehicle based on route information input by the driver or automatically calculated, as well as road information such as the curvature, slope, and turning radius of a specific road on a road related to a preceding vehicle from a regional traffic control system using V2I communication and / or from a preceding vehicle using V2V communication, and can use the collected road information to set a target speed profile. The target speed profile can be automatically generated whenever the driver sets a target speed or changes the route, regardless of the current state of the CACC system.

[0103] The target speed profile generated by the profile management unit 330 may be transmitted to the driving management unit 333 , and the driving management unit 333 may control the driving speed of the subject vehicle to match the target speed profile.

[0104] However, if there is a target vehicle traveling at a constant speed ahead, although the target speed profile is set and the subject vehicle travels accordingly, the travel management unit 333 may perform control ignoring the target speed profile in order to match the interval distance or time interval for preset safety. Figure 5 As shown in the example of , in a case where the speed of the target vehicle is lower than the speed according to the target speed profile, if the subject vehicle travels according to the target speed profile, a collision will occur between the subject vehicle and the target vehicle after a period of time.

[0105] That is, if the current time is t0, a collision may occur within the minimum time t1 below which is achieved.

[0106]

[0107] Here, D(t0) represents the distance between the subject vehicle and the target vehicle at t0, V old_calc (t) represents the driving speed of the subject vehicle at time t through the target speed curve, and V target Indicates the target vehicle's speed.

[0108] To prevent such a collision, the driving management unit 333 may perform follow-up control regardless of the target speed profile, but to maximize fuel efficiency, it is necessary to set a new target speed profile and perform driving accordingly. Therefore, the driving management unit 333 may request the profile management unit 337 to set a new target speed profile based on the presence of the target vehicle, and the profile management unit 337 may set the new target speed profile to match this request.

[0109] As an example of setting a new target speed profile, the profile management unit 337 may set a new target speed profile to match the speed of the target vehicle.

[0110] Figure 6 FIG. 3 is a schematic diagram illustrating a new target speed curve set by the curve management unit 337 according to the driving speed of the target vehicle.

[0111] refer to Figure 6 The curve management unit 337 can set a new target speed curve V based on the driving speed of the target vehicle. new_calc_0 (t). The newly set target speed profile may be transmitted to the driving management unit 333 to control the driving speed of the subject vehicle. That is, if there is a target vehicle, the profile management unit 337 may set a new target speed profile having the same speed variation as that of the target speed profile in the prior art based on the driving speed of the target vehicle instead of the target speed set by the driver, so as to improve or maximize fuel efficiency. Figure 6 For example, if the target speed set by the driver is 80 km / h and the driving speed of the target vehicle is 60 km / h, the curve management unit 337 may set the new fuel efficiency improvement target speed curve to V new_calc0 =V old_calc (t) -20. The newly set target speed profile may be transmitted to the driving management unit 333, and the driving management unit 333 may manage driving according to the newly set target speed profile.

[0112] However, when setting a new fuel efficiency improvement target speed curve in this method, it is necessary to determine whether the preset minimum separation distance or minimum time interval can be maintained. If not, the driving management unit 333 is required to perform speed change including an artificial deceleration section.

[0113] More specifically, when the subject vehicle is traveling at the new target speed profile, in order to prevent a collision between the subject vehicle and the target vehicle, the distance between the subject vehicle and the target vehicle should meet a preset allowable minimum distance Dmin or a preset allowable time interval τ minutes. Here, the allowable minimum distance Dmin may be Dmin = τ minutes × E(V). Here, E(V) may be the average value of the driving speed of the subject vehicle during the time interval τ minutes. In this case, if the current distance between the subject vehicle and the target vehicle is equal to or greater than Ds calculated by the following equation, then when the subject vehicle is traveling at the new target speed profile, the minimum distance between the subject vehicle and the target vehicle becomes greater than Dmin to prevent a collision. That is, Ds may refer to the minimum distance used to prevent a collision between the target vehicle and the subject vehicle while following the new target speed profile, and may be calculated by the following equation.

[0114] Ds=Dmin+|min(Δd)|

[0115] Here, min(A) refers to the minimum value of A, and |B| refers to the absolute value of B. In addition, Δd is the relative distance change between the subject vehicle and the target vehicle, and the target vehicle speed V can be expressed as follows: target With the newly set target speed curve V new_calc_0 (t) is calculated by integrating the differences between them.

[0116] Δd=∫(V target -V new_calc_0 (t))dt

[0117] Referring to the above equation, min(Δd) may be a maximum distance narrowed by a speed difference between the subject vehicle and the target vehicle.

[0118] Therefore, if the current inter-vehicle distance between the target vehicle and the subject vehicle is less than Ds, there is a possibility of collision when driving with the newly set target speed profile, and therefore a speed change including an artificial deceleration section for ensuring Ds may be additionally required.

[0119] Figure 7 1 is a diagram illustrating an example of setting a new target speed profile to maintain a preset minimum vehicle distance or minimum time interval after deceleration is performed according to an embodiment of the present invention.

[0120] refer to Figure 7 , when driving is performed to follow the V set as the new target speed curve by the curve management unit 337 new_calc_0 In the case of (t), it is determined that the preset minimum vehicle distance or minimum time interval cannot be maintained, and therefore additional deceleration needs to be performed.

[0121] Additional deceleration can be performed by the main brake (friction brake) or an auxiliary deceleration device. Here, auxiliary deceleration can refer to a device that can decelerate the vehicle in addition to the main brake (friction brake), and can include all devices such as fuel cutoff, engine braking, auxiliary braking (retarder or exhaust brake), and kinetic energy coasting (neutral state). Compared with the case of using the main brake, auxiliary deceleration can improve fuel efficiency and slow down the vehicle.

[0122] According to the deceleration method, the speed V of the deceleration section set by the driving management unit 333 is calculated. decel In the embodiment of the present invention, when deceleration is performed using an auxiliary deceleration device such as fuel cutoff, the speed V at each time is decel (t) can be calculated as follows.

[0123] V decel (t)=∫a Fuelcut dt+V current

[0124] Here, a Fuelcut refers to the vehicle acceleration in the case where the auxiliary deceleration device is executed (deceleration has a negative (-) value), and V current Indicates the current speed of the subject vehicle.

[0125] However, if the calculated V decel (t) Lower than the minimum speed V preset in the CACC system low_limit , then V decel (t) may be set as a minimum speed. Here, as the minimum speed, a value equal to or greater than a first speed capable of changing the state of the CACC system from the active state 600 to the standby state 500 may be used.

[0126] If artificial deceleration is performed as described above, Figure 7 As shown, the marginal distance from the target vehicle is ensured (710). After ensuring the marginal distance, the driving management unit 333 may request the curve management unit 337 to generate a new target speed curve, and the curve management unit 337 may generate a new target speed curve V according to the request. new_calc_t (t). The driving management unit 333 may calculate the driving cost during driving based on the new target speed profile, maintain the driving cost during driving and at the current speed, and control the driving speed of the subject vehicle using a driving method with a low driving cost. Here, the driving cost may refer to a cost calculated by taking into account all economic consumption factors including the fuel consumption required for vehicle driving.

[0127] In an embodiment, the driving management unit 333 may calculate the driving cost Cc when the current speed is maintained during driving and the driving cost Cc when the new target speed curve V is used. new_calc_t (t) The driving cost Ccontrol of the vehicle under driving conditions, and the calculated driving costs can be compared with each other. If Ccontrol is less than Cc, the driving management unit can also set the minimum speed V preset in the CACC system 300 to low_limit It is compared with the current driving speed Vc of the subject vehicle, and if the current driving speed Vc is higher than the minimum speed V low_limit , the driving management unit can ensure a distance equal to or longer than Ds by performing deceleration through the auxiliary deceleration device. If the current driving speed Vc is lower than the minimum speed V low_limit , the driving management unit 333 can be based on the minimum speed V low_limit To keep moving.

[0128] In contrast, if Cc is less than Ccontrol, the driving management unit can compare the current speed of the vehicle with the driving speed V of the target vehicle. targetThe comparison is performed and the target vehicle's driving speed, the current driving speed of the subject vehicle, the preset minimum speed of the subject vehicle, the auxiliary deceleration device until the target vehicle's driving speed V is reached are considered. target The required distance Dcruise is then applied by braking until the target vehicle reaches its speed V. target The required distance Dbrake and the distance margins M1 and M2 according to the deceleration method set the traveling speed of the vehicle.

[0129] More preferably, if the current speed of the vehicle is lower than the speed of the target vehicle, the driving management unit may be set to maintain the current speed, and if the current speed of the vehicle is higher than the speed of the target vehicle, the driving management unit may combine the current distance to the target vehicle with the speed of the target vehicle to reach the driving speed V of the target vehicle by decelerating the subject vehicle through the auxiliary deceleration device. target The required distance is compared with the value obtained by summing the distance margins M1 according to the deceleration method.

[0130] In addition, if the auxiliary deceleration device is used to decelerate the subject vehicle to reach the target vehicle's running speed V target If the value obtained by summing the required distance and the distance margin M1 according to the deceleration method is greater than the current distance to the target vehicle, the driving management unit can calculate the current distance to the target vehicle and the driving speed V required to reach the target vehicle by braking. target The required distance Dbrake is compared with the value obtained by summing the distance margin M2 according to the deceleration method. Here, the distance Dbrake may include the minimum separation distance Dmin set in the CACC system. That is, the distance Dbrake may be obtained by braking the vehicle to the target vehicle speed V target The distance Dx is defined as the sum of the required distance Dx and the minimum separation distance Dmin. The distance Dx is always less than the speed V of the target vehicle that is decelerated by the auxiliary deceleration device. target The value of the required distance, and in this case, the braking range can be within the braking range allowed in the CACC system.

[0131] Figure 8 FIG. 1 is a diagram illustrating an example of a driving speed of a subject vehicle according to an inter-vehicle distance and the sizes of costs Cc and Ccontrol according to the present invention.

[0132] refer to Figure 8 Segment A corresponds to the case where the current inter-vehicle distance Dc1 is greater than Dx. In this case, since a safe inter-vehicle distance is ensured, a collision with the target vehicle will not occur even if the current target speed profile is followed, so driving according to the set target speed profile can be performed.

[0133] On the contrary, the section B corresponds to the current vehicle distance Dc2 being less than Dx but greater than the target vehicle travel speed V by the auxiliary deceleration device. target The sum of the required distance Dcruise and the distance margin when the auxiliary deceleration device is used, and driving is performed to maintain the current vehicle speed.

[0134] Here, M1 is a certain value set by the user according to the distance measurement error between the subject vehicle and the target vehicle and the speed control error of the CACC system, and may be set to a value equal to or greater than 0. More preferably, M1 may include a certain value set by the vehicle manufacturer during factory shipment.

[0135] Dcruise can refer to the speed V of the target vehicle that is decelerated by the auxiliary deceleration device. target The required distance can be calculated by the following equation.

[0136] D cruise =∫0 t V decel (τ)dτ+Dmin

[0137] Section C corresponds to the current vehicle distance Dc3 being less than the target vehicle speed Vc3, which is reduced by the auxiliary deceleration device. target The distance Dcruise and the distance margin M1 according to the auxiliary deceleration device are combined, and a configuration for performing deceleration by the auxiliary deceleration device is disclosed. Thereafter, in section D, the driving speed of the subject vehicle may be equal to the driving speed V of the target vehicle. target , in order to maintain the current workshop distance.

[0138] As described above, Dc1, Dc2, and Dc3 are certain amounts indicating the current inter-vehicle distance given at different determination time points, and continuous distance determination may be performed at each time point.

[0139] Figure 9 FIG. 1 is a diagram illustrating a change in the inter-vehicle distance between a subject vehicle and a target vehicle when the subject vehicle is traveling at a constant speed higher than that of the target vehicle according to an embodiment of the present invention.

[0140] refer to Figure 9 Section A1 is the section where the subject vehicle maintains its current speed. In Section A1, the target vehicle travels at a constant speed, thereby reducing the inter-vehicle distance between them. Section B1 corresponds to a situation where the current inter-vehicle distance Dc1 is less than the sum of Dcruise and M1 and greater than the sum of Dbrake and M2. In Section B1, the auxiliary deceleration device reduces relative speed, resulting in a lower slope of inter-vehicle distance reduction compared to Section A1.

[0141] Here, M2 is a value set in consideration of deceleration that can provide a comfortable braking force to the driver when performing braking, and can be optionally set by the user or at the time of vehicle shipment in consideration of a vehicle speed error and a braking force set in the CACC system.

[0142] More preferably, the setting M2 may be set in consideration of a deceleration value that enables the driver to feel smooth braking, and the deceleration for smooth braking may be set within a range lower than a maximum deceleration set in the CACC system.

[0143] The distance margin M2 according to braking may have a value smaller than that of the distance margin M1 according to the auxiliary deceleration device, and the value may be a negative value.

[0144] Furthermore, the value Dbrake+M2 should be set to be always smaller than the value Dcruise+M1, and the sum of the deceleration distance due to braking and the distance margin M2 should be smaller than the sum of the deceleration distance by the auxiliary deceleration device and the distance margin M1.

[0145] Section C1 may be a section requiring emergency braking, and may occur due to the sudden intrusion of a potential vehicle of interest or the deceleration of a target vehicle. In section C1, the current inter-vehicle distance Dc2 becomes less than the sum of Dbrake and the distance margin M2 due to braking, and in this case, the brakes may be used to brake the subject vehicle.

[0146] exist Figure 9 In the graph shown, sections B1 and C1 are configured to pass through the auxiliary deceleration device until the target vehicle reaches the travel speed V by comparing the current vehicle distance during the determination period with the vehicle distance and the vehicle distance under the condition that the subject vehicle travels at a normal speed higher than that of the target vehicle. target The sum of the distances required to control the movement of the subject vehicle.

[0147] Figure 10 Schematic diagram showing the distance relationship among Dcruise, Dbrake, M1 and M2.

[0148] refer to Figure 10 In an embodiment of the present invention, it is disclosed that an auxiliary deceleration device (in Figure 10 In the example of fuel cutoff, the distance Dcruise obtained by summing the distance Dfuelcut over which deceleration is performed and the minimum distance Dmin set in the CACC system is obtained. Figure 10 The start time 1010 of executing the fuel cut as the auxiliary deceleration means is shown, and further the time 1010 of executing the fuel cut as the auxiliary deceleration means is shown. targetThe time 1020 to perform braking within the range of the required distance Dx and the deceleration set in the CACC system).

[0149] M1 is the distance margin when deceleration is performed by the auxiliary deceleration device and can be set by the user in consideration of the speed error and distance measurement error for the target vehicle. M2 is the distance margin during braking and can correspond to the measurement and setting error.

[0150] like Figure 10 As shown, Dfuelcut has a value that is physically greater than the values of Dx and Dmin, and the value of Dcruise is also greater than the value of Dbrake.

[0151] Figure 11 4 is a flowchart of a control method for improving fuel efficiency of a CACC system using a target speed profile if a target vehicle exists according to an embodiment of the present invention.

[0152] In the case of the CACC system according to the present invention, it is determined whether to start operation of the CACC system (S10). If the CACC system is not operating, speed control is not performed (S50). However, if the CACC system is operating, a target speed profile may be set based on the target speed and the expected driving path of the subject vehicle (S20). As an example, when the CACC system transitions from the off state 400 to the standby state 500, the target speed profile may be set. The target speed profile may be set based on path information set by the user, taking into account the road grade, curvature, and inclination stored in the control unit.

[0153] As described above, after the target speed profile is set, a determination is made as to whether a target vehicle exists (S30). If the target vehicle does not exist, the subject vehicle's travel is controlled according to the set target speed profile (S60). If the target vehicle exists, a process is performed to compare the current inter-vehicle distance Dc between the target vehicle and the subject vehicle with a minimum distance Ds that would prevent a collision with the target vehicle even if the subject vehicle were traveling according to the target speed profile (S40).

[0154] As a result of the comparison, if Dc is greater than Ds, traveling is controlled according to the target speed profile set in S20 ( S60 ), and if Dc is less than Ds, fuel efficiency traveling may be performed ( S100 ).

[0155] Fuel-efficient driving can be performed by considering the driving cost Cc of driving in the case of maintaining the decelerated current speed after deceleration so that Ds becomes less than Dc, the driving cost Ccontrol of driving according to a new target speed curve generated based on the decelerated current speed, the target vehicle speed, the current speed of the subject vehicle, the minimum driving speed set in the subject vehicle, the distance required to reach the target vehicle speed Vtarget by the auxiliary deceleration device without releasing the CACC system, and the distance margin according to the deceleration method.

[0156] Figure 12 is a flowchart illustrating a control method for performing fuel-efficient driving according to an embodiment of the present invention.

[0157] In order to perform fuel-efficient driving, the CACC system compares a driving cost Cc of maintaining the current speed of the subject vehicle after deceleration so that Ds becomes less than Dc in the case of constant speed driving with a driving cost Ccontrol in the case of driving according to a new target speed curve generated based on the decelerated current speed (S110).

[0158] In this case, if Cc is greater than Ccontrol, the CACC system compares the current speed of the subject vehicle with a minimum speed Vlow_limit set in the CACC system ( S111 ).

[0159] If the current speed of the subject vehicle is higher than the minimum speed, the CACC system operates to decelerate the subject vehicle through the auxiliary deceleration device (S112), and if the current speed of the subject vehicle is lower than the minimum speed, the CACC system operates to drive the subject vehicle at the minimum speed (S123).

[0160] In contrast, if Cc is less than Ccontrol, the CACC system compares the current speed of the subject vehicle with the speed of the target vehicle (S120). If the current speed of the subject vehicle is lower than the speed of the target vehicle, the CACC system drives the subject vehicle by maintaining the current speed (S121), while if the current speed of the subject vehicle is higher than the speed of the target vehicle, the CACC system compares the current distance Dc2 between the subject vehicle and the target vehicle with the speed of the target vehicle through the auxiliary deceleration device until the target vehicle reaches the driving speed V targetThe required distance Dcruise is compared with the sum of the distance margin M1 required for the auxiliary deceleration device (S130). If the current distance Dc2 between the subject vehicle and the target vehicle is greater than the sum of Dcruise and the distance margin M1 for determining the time of the auxiliary deceleration device, the CACC system is set to maintain the current speed (S133), and if the distance Dc2 between the subject vehicle and the target vehicle is less than the sum of Dcruise and M1, the CACC system compares the distance Dc2 between the subject vehicle and the target vehicle with the sum of the distance Dbrake required to brake by the brake until the target vehicle reaches the driving speed and the distance margin M2 required during braking (S131).

[0161] If the current distance Dc2 between the subject vehicle and the target vehicle is less than the sum of Dbrake and the distance margin M2, the CACC system performs braking through the brake (S132), and if the current distance Dc2 between the subject vehicle and the target vehicle is greater than the sum of Dbrake and the distance margin M2, the CACC system performs deceleration through the auxiliary deceleration device.

[0162] As described above, according to the present invention, the vehicle can be controlled to improve fuel efficiency under adverse traffic conditions by applying the above logic each time to control the vehicle to follow the optimal fuel-efficient driving curve or speed.

[0163] On the other hand, it should be understood that for ease of explanation, CACC is illustrated in the specification. CACC is only one of the various ADAS functions, and the CACC implementation scheme proposed according to the present invention can also be used to implement other related ADAS functions. For example, the method proposed according to the present invention can even be used to implement one or a combination of the following ADAS functions: such as CACC, ACC (adaptive cruise control), LCDAS (lane change determination assist system), LDWS (lane departure warning system), LKAS (lane keeping assist system), RBDPS (road boundary departure prevention system), PDCMS (pedestrian detection and collision mitigation system), CSWS (curve speed warning system), FVCWS (forward vehicle collision warning system) and LSF (low speed follow).

[0164] In one or more exemplary embodiments, the functions described can be implemented by hardware, software, firmware, or some combination thereof. In the case of software implementation, these functions can be stored or sent to a computer-readable medium as one or more instructions or codes. Computer-readable media include communication media and computer storage media, and computer storage media include specific media that help transfer computer programs from one place to another. Storage media can be specific available media that can be accessed by a computer. For example, but not limited to, this computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or another optical disk storage, magnetic disk storage or another magnetic storage device, or another medium that can be accessed by a computer and can be used to transfer or store desired program code in the form of instructions or data structures. In addition, a certain connection can be appropriately referred to as a computer-readable medium. For example, if a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared, radio, or ultra-high frequency is used to send software from a website, server, or another remote source, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology such as infrared, radio, or ultra-high frequency is included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc. Generally speaking, disks reproduce data magnetically, while optical discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0165] In the situation that embodiment is realized by program code or code segment, should recognize that code segment can indicate some combination of program, function, subroutine, program, routine, subroutine, module, software package, class or instruction, data structure or program command.Code segment can be connected to another code segment or hardware circuit by transmitting and / or receiving information, data, variable, parameter or memory content.Information, variable, parameter and data can use some appropriate mode that comprises memory sharing, message transmission, token transmission and network transmission to transmit, send or transmit.In addition, in some respects, the step of method or algorithm and / or operation can be used as one, combination or a group of code and / or command on machine-readable medium and / or computer-readable medium, and it can be integrated into the thing of computer program.

[0166] In the case of a software implementation, the above techniques can be implemented by modules (e.g., programs or functions) that perform the above functions. The software code can be stored in a memory module and can be executed by a processor. The memory unit can be implemented in the processor or external to the processor, and in this case, the memory unit can be communicatively connected to the processor by various means known in the art.

[0167] In the case of a hardware implementation, the processing unit may be implemented in at least one of an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, other electronic units designed to perform the functions described above, and combinations thereof.

[0168] As described above, one or more embodiments are illustrated. For the purpose of explaining the above embodiments, not all possible combinations of components or methods are described, but those skilled in the art will recognize that many additional combinations and permutations of the various embodiments are possible. Therefore, the above embodiments may include all substitutions, modifications, and variations within the true meaning and scope of the appended claims. In addition, the terms "comprising" and / or "consisting of" as used in the specification and claims mean that in addition to the described components, steps, operations, and / or devices, the presence or addition of one or more other components, steps, operations, and / or devices is not excluded.

[0169] As used herein, the term "estimation" or "estimation" refers to the process of determining or estimating a state of a system, environment, and / or user from a set of observations typically occupied by events and / or data. The estimation can be used to identify a specific situation or operation and can generate, for example, a probability distribution of states. The estimation can be probabilistic and a probability distribution of corresponding states can be calculated based on a consideration of data or events. The estimation can be a technique for constructing upper-level events from a set of events and / or data. This estimation can estimate new events or operations from a set of observed events and / or stored event data, regardless of whether the events are closely related in time and whether the events and data are from one or more event and data sources.

[0170] In addition, the terms "component", "module" or "system" used in the description of the present invention are not limited thereto, but may include hardware, firmware, a combination of hardware and software, software or computer-related entities, such as software being executed. For example, a component is not limited to its name, but may be a process executed on a processor, a processor, an object, an executable execution thread, a program and / or a computer. Exemplary, an application driven by an operating device and an operating device may be a component. One or more components may reside in a process and / or execution thread, and the components may be concentrated in one computer and / or may be distributed between two or more computers. In addition, such components may be executed from various computer-readable media storing various data structures. Components may communicate with each other through local and / or remote processes based on signals having one or more data packets (e.g., data from a local system, another component of a distributed system and / or a component that interacts with other systems by signals over a network such as the Internet).

[0171] It should be understood that the above embodiments are exemplary to help facilitate understanding of the present invention, but do not limit the scope of the present invention. Therefore, the scope of the present invention is defined by the appended claims, and should be interpreted as all amendments and modifications derived from the meaning and scope of the appended claims and their equivalent concepts fall within the scope of the present invention.

Claims

1. A cooperative adaptive cruise control (CACC) system provided in a subject vehicle for controlling a driving speed of the subject vehicle, comprising: a communication unit configured to receive vehicle information including position and driving information from a neighboring vehicle using vehicle-to-vehicle (V2V) communication; an information collecting unit configured to collect driving information of a preceding vehicle and vehicle information of the subject vehicle using sensors provided on the subject vehicle; as well as a control unit configured to select a target vehicle to be followed by the subject vehicle from the adjacent vehicles located in the area of interest based on the vehicle information of the adjacent vehicles acquired by the communication unit and the driving information of the preceding vehicle collected by the information collection unit, Wherein, the control unit is further configured to: If there is no vehicle connected by vehicle-to-vehicle (V2V) communication in the area of interest, controlling the travel speed of the subject vehicle based on the target speed of the subject vehicle, controlling a travel speed of the subject vehicle based on information received from the potential vehicle of interest through vehicle-to-vehicle (V2V) communication if there is a potential vehicle of interest connected through vehicle-to-vehicle (V2V) communication in the area of interest and the target vehicle is not present, If the target vehicle present in the area of interest is not connected through vehicle-to-vehicle (V2V) communication, controlling a travel speed of the subject vehicle based on information received from the potential vehicle of interest through vehicle-to-vehicle (V2V) communication and information about the target vehicle detected by the information collecting unit of the subject vehicle, If the target vehicle present in the area of interest is connected through vehicle-to-vehicle (V2V) communication, a travel speed of the subject vehicle is controlled based on information received from the potential vehicle of interest and the target vehicle through vehicle-to-vehicle (V2V) communication.

2. The cooperative adaptive cruise control (CACC) system of claim 1 , further comprising: A drive unit configured to control the throttle and brake, The control unit controls the driving unit to control the driving speed of the subject vehicle.

3. The cooperative adaptive cruise control (CACC) system of claim 1 , further comprising: A driver vehicle interface (DVI) unit is configured to receive the target speed and / or target time interval input from a driver and inform the driver of status information of the cooperative adaptive cruise control (CACC) system.

4. The cooperative adaptive cruise control (CACC) system according to claim 1, wherein: The control unit comprises: a state management unit configured to manage a state of the cooperative adaptive cruise control (CACC) system; a target vehicle selecting unit configured to select the target vehicle to be followed by the subject vehicle from the neighboring vehicles located in an area of interest based on the vehicle information of the neighboring vehicle acquired from the communication unit and the driving information of the preceding vehicle collected by the information collecting unit; a curve management unit configured to set a target speed curve based on the target speed and the expected travel path of the subject vehicle if the target vehicle selected by the target vehicle selection unit does not exist, and to set a target speed curve based on speed information of the target vehicle, speed information of the subject vehicle, and the expected travel path if the target vehicle selected by the target vehicle selection unit exists; and The driving management unit is configured to control the driving speed of the subject vehicle according to the set target speed curve.

5. The cooperative adaptive cruise control (CACC) system according to claim 4, wherein: the state management unit displays the state of the cooperative adaptive cruise control (CACC) system as one of the following: an off state in which the cooperative adaptive cruise control (CACC) system does not operate; a standby state in which the cooperative adaptive cruise control (CACC) system operates but does not control the travel speed of the subject vehicle; and an adaptive cruise control active state in which, in a state in which no vehicle connected by vehicle-to-vehicle communication exists in an area of interest, the travel speed of the subject vehicle is controlled using only information acquired from the subject vehicle. and a cooperative activation state in which the neighboring vehicle connected by vehicle-to-vehicle communication exists in the area of interest and the traveling speed of the subject vehicle is controlled using information from the neighboring vehicle acquired by the vehicle-to-vehicle communication and information acquired from the subject vehicle.

6. The cooperative adaptive cruise control (CACC) system according to claim 4, wherein: If there is a possibility of collision when the driving speed of the subject vehicle is controlled according to the set target speed curve, the driving management unit requests the curve management unit to set a new target speed curve, and The curve management unit resets the target speed curve based on the speed information of the target vehicle, the speed information of the subject vehicle, and expected path information according to the request for setting the new target speed curve from the travel management unit.

7. A control method for improving fuel efficiency in a cooperative adaptive cruise control (CACC) system, wherein the cooperative adaptive cruise control (CACC) system is provided in a subject vehicle for controlling the driving speed of the subject vehicle, the control method comprising the following steps: determining whether to activate the cooperative adaptive cruise control (CACC) system; Setting a target speed curve based on the target speed and the expected travel path of the subject vehicle; Determining whether there is a target vehicle that the subject vehicle is to follow among adjacent vehicles located in the area of interest; As a result of the determination, if the target vehicle does not exist, controlling the travel speed of the subject vehicle according to the set target speed profile; As a result of the determination, if the target vehicle exists, comparing a minimum distance Ds with a current distance Dc to the target vehicle, wherein a collision with the target vehicle can be prevented even if the subject vehicle travels the minimum distance Ds according to the target speed profile; and As a result of the comparison, if the current distance Dc is greater than the minimum distance Ds, the driving speed of the subject vehicle is controlled according to the target speed profile, and if the current distance Dc is less than the minimum distance Ds, fuel-efficient driving is performed, wherein the fuel-efficient driving is performed in consideration of: a driving cost Cc in a case where the vehicle is driven at the decelerated current speed after deceleration so that the minimum distance Ds becomes smaller than the current distance Dc; a driving cost Ccontrol in a case where the vehicle is driven according to a new target speed curve generated based on the decelerated current speed; the speed of the target vehicle; the speed of the subject vehicle; the minimum driving speed set in the subject vehicle; the distance required to reach the target vehicle speed Vtarget by the auxiliary deceleration device; and a distance margin according to the deceleration method, If there is no adjacent vehicle in the region of interest, the driving speed of the subject vehicle is affected by the target speed of the subject vehicle. If there is a potential vehicle of interest connected through vehicle-to-vehicle (V2V) communication in the area of interest and the target vehicle is not present, the driving speed of the subject vehicle is affected by information received from the potential vehicle of interest through vehicle-to-vehicle (V2V) communication, If the target vehicle present in the area of interest is not connected through vehicle-to-vehicle (V2V) communication, the driving speed of the subject vehicle is affected by information received from the potential vehicle of interest through vehicle-to-vehicle (V2V) communication and information about the target vehicle detected by an information collection unit of the subject vehicle, If the target vehicle present in the area of interest is connected through vehicle-to-vehicle (V2V) communication, the driving speed of the subject vehicle is affected by information received from the potential vehicle of interest and the target vehicle through vehicle-to-vehicle (V2V) communication.

8. The control method according to claim 7, wherein: Executing the fuel-efficient driving includes: Comparing the following: the driving cost Cc when the subject vehicle is traveling at a current constant speed after deceleration so that the minimum distance Ds becomes smaller than the current distance Dc; and the driving cost Ccontrol when traveling according to the new target speed curve generated based on the decelerated current speed; As a result of the comparison, if the driving cost Cc is less than the driving cost Ccontrol, maintaining constant speed travel at the current speed of the subject vehicle or performing deceleration by comparing the current speed of the subject vehicle with the speed of the target vehicle; and As a result of the comparison, if the driving cost Cc is greater than the driving cost Ccontrol, the current speed of the subject vehicle is compared with a minimum speed set in the subject vehicle, Wherein, the current speed of the subject vehicle is compared with the minimum speed set in the subject vehicle, including: if the current speed of the subject vehicle is higher than the minimum speed set in the subject vehicle, deceleration driving is performed through the auxiliary deceleration device; if the current speed of the subject vehicle is lower than the minimum speed set in the subject vehicle, driving is performed at the minimum speed set in the subject vehicle.

9. The control method according to claim 8, wherein: Maintaining constant speed travel at the current speed of the subject vehicle or performing deceleration by comparing the current speed of the subject vehicle with the speed of the target vehicle further comprises: If the current speed of the subject vehicle is lower than the speed of the target vehicle, performing travel at the current speed of the subject vehicle; and If the current speed of the subject vehicle is greater than the speed of the target vehicle, the following items are compared: the current distance Dc2 between the subject vehicle and the target vehicle; the sum of the distance Dcruise required to reach the driving speed of the target vehicle through the auxiliary deceleration device and the distance margin M1 according to the auxiliary deceleration device.

10. The control method according to claim 9, wherein: Comparing the sum of the distance Dcruise and the distance margin M1 with the current distance Dc2 includes: If the current distance Dc2 is greater than the sum of the distance Dcruise and the distance margin M1, performing travel at the current vehicle speed; and If the current distance Dc2 is less than the sum of the distance Dcruise and the distance margin M1, the following items are compared: the current distance Dc2; the sum of the distance Dbrake required to reach the driving speed of the target vehicle by performing braking by the brake and the distance margin M2 required during braking by the brake.

11. The control method according to claim 10, wherein: The current distance Dc2 is compared with the sum of the distance Dbrake and the distance margin M2, including: if the current distance Dc2 is greater than the sum of the distance Dbrake and the distance margin M2, deceleration is performed by the auxiliary deceleration device of the vehicle, and if the current distance Dc2 is less than the sum of the distance Dbrake and the distance margin M2, deceleration is performed by braking with the brake.

12. The control method according to claim 7, wherein: The target speed profile is set in consideration of road information regarding the vehicle's travel path.

13. The control method according to claim 12, wherein: The road information includes road curvature, grade, and turning radius.

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