Method for automatic acceleration adjustment in a motor vehicle

Abstract

A method for automatic acceleration adjustment in a motor vehicle (1), wherein a detection device (2) determines a speed limit applicable to a road section, wherein a cruise control device (6) determines a cruise control target acceleration based on the speed limit, and wherein a control device (8) controls a drive device (9) of the motor vehicle (1) with a drive target acceleration based on the cruise control target acceleration, wherein a distance control device (12) determines a distance control target acceleration based on a detected vehicle distance to a preceding vehicle (13), and the drive target acceleration is limited by the distance control target acceleration such that the drive target acceleration remains below the distance control target acceleration, characterized in that the detection device (2) comprises a radio device (28) which wirelessly receives route information from a stationary route device for determining the speed limit, wherein the cruise control device (6) determines the cruise control target acceleration based on an active target acceleration profile, wherein the target acceleration profile defines a target acceleration profile over time (26, 27), wherein the detection device (2) comprises a map processing device (5) which reads route information from a map for the road segment in order to determine the speed limit, wherein the detection device (2) for determining the speed limit wirelessly receives route information from a remote vehicle, and wherein the map processing device (5) estimates a route to be travelled by the motor vehicle based (1) on a probability calculation and the road segment lies on this estimated route.

Description

[0001] The invention relates to a method for automatic acceleration adjustment in a motor vehicle according to the preamble of claim 1.

[0002] Adaptive cruise control systems are known from the prior art; these regulate the speed of the vehicle in such a way that a desired distance or a defined distance range to a vehicle ahead is maintained. This significantly reduces the driver's workload, as they no longer have to perform the corresponding braking and acceleration maneuvers themselves.

[0003] For example, a generic method for automatic acceleration adjustment in a motor vehicle is known from DE 10 2010 006 442 A1.

[0004] Furthermore, DE 10 2013 224 716 A1 discloses a method for operating a motor vehicle to perform a diagnostic and / or adaptation function, in which the vehicle's speed can be automatically adjusted to achieve an operating state required for performing the diagnostic and / or adaptation function. Among other things, this involves determining an upcoming road segment and providing road characteristics for that segment. Road characteristics, such as speed, altitude, and curve information, can be obtained from a digital navigation map stored in a navigation system. The upcoming road segment can also be determined as the section of the vehicle's route that the driver is most likely to travel.

[0005] Furthermore, WO 2015 / 047177 A1 discloses a method for controlling a vehicle convoy in which the vehicle control can be carried out on the basis of a driving profile of a vehicle in the convoy, wherein the driving profile can include target speeds, target acceleration values ​​or target distances.

[0006] EP 1 930 863 B1 describes a system for the automatic recognition of traffic signs and mentions in principle the possibility of integrating such a system into an adaptive cruise control system.

[0007] DE 10 2011 053 778 A1 describes a system for the automatic recognition of traffic signs and proposes to adjust the accelerator pedal sensitivity depending on a detected speed limit.

[0008] US Patent 2012 / 0253628 A1 describes a motor vehicle equipped with a camera system for automatic traffic sign recognition and an adaptive cruise control system to which a target speed can be set. If a speed limit is detected based on a traffic sign that does not correspond to the target speed, the adaptive cruise control is deactivated and, if necessary, reactivated with a target speed updated to reflect the speed limit.

[0009] German patent DE 103 03 010 A1 describes a motor vehicle equipped with adaptive cruise control and a system for automatically detecting and evaluating traffic signs. It proposes that when driving on a section of road with a speed limit, this speed limit should increase the target speed determined by the adaptive cruise control. This is intended to prevent the prescribed speed limit from being exceeded while maintaining a safe distance.

[0010] GB 2 520 130 A discloses a vehicle speed control system comprising a control unit that steers a vehicle to maintain a set speed. The system determines the current legal speed limit by using an image sensor, such as a camera, to detect speed limit signs and / or a navigation system and / or information media that receive data from, for example, a smart speed limit sign. Depending on the current legal speed limit and environmental and / or situational conditions, the system determines a suitable vehicle speed, which is output to a human-machine interface to prompt the driver to select the appropriate vehicle speed as the cruising speed.

[0011] However, a disadvantage of this prior art is that this approach prioritizes the predetermined speed limit over other factors, such as safe distance control and driving comfort. Therefore, the object of the invention is to provide an improved consideration of speed limits in automatic distance control.

[0012] This problem is solved with respect to a method for automatic acceleration adjustment according to the preamble of claim 1 by the features of the characterizing part of claim 1.

[0013] The method according to the invention serves for the automatic acceleration adjustment of a motor vehicle. A detection device determines a speed limit that applies to a section of road. Preferably, the motor vehicle includes the detection device. This speed limit can be specified by a standard, such as the road traffic regulations or the like, or it can be a practical requirement resulting from the current traffic situation or the road layout. Furthermore, a cruise control device determines a target acceleration based on the speed limit. Preferably, the motor vehicle also includes the cruise control device. Any type of acceleration, as used here and subsequently, also includes negative acceleration in the sense of deceleration.According to the invention, a control device controls a drive device of the motor vehicle based on the cruise control setpoint acceleration. The motor vehicle comprises the control device and the drive device. The drive device acts on the motor and brakes of the motor vehicle to adjust the actual acceleration of the motor vehicle.

[0014] The method according to the invention further provides that a distance control device determines a target acceleration based on a detected vehicle distance to a vehicle ahead, and that the target acceleration of the drive is limited by the target acceleration of the distance control in such a way that the target acceleration of the drive remains below the target acceleration of the distance control. A vehicle ahead is understood to be another vehicle that has already traveled the road segment at a distance from the motor vehicle or is about to travel the road segment.

[0015] According to the inventive method, the detection device comprises a radio device which wirelessly receives route information from a stationary route device, for example a traffic light or other traffic signal system, to determine the speed limit.

[0016] The invention recognizes that, even more important than avoiding exceeding a speed limit indicated by a traffic sign, it is crucial to prevent the desired speed set by the cruise control from causing the vehicle to accelerate sharply if this simultaneously leads to a rapid reduction in the distance to the vehicle ahead. The invention therefore aims to prevent excessive acceleration, particularly since this regularly results in reverse corrective interventions, such as hard braking in response to excessive acceleration. This benefits both comfort and fuel consumption.

[0017] According to a preferred embodiment, the detection device determines a speed limit that applies to a section of road currently being traveled by the vehicle. Alternatively or additionally, the detection device can preferably determine a speed limit that applies to a section of road to be traveled in the future, within the vehicle's line of sight. It is also possible that this section of road to be traveled in the future applies outside the vehicle's line of sight. For the purposes of determining line of sight, the focus here is not only on distance, but on the existence of an unobstructed line of sight.

[0018] Another preferred embodiment is characterized in that the detection device comprises a camera arrangement which optically captures route information to determine the speed limit. In this way, the route information can be determined dynamically. The detection device includes a map processing device which reads route information from a map of the road segment to determine the speed limit. This map can be stored in a map memory of the map processing device containing the route information or a plurality of route information.

[0019] The map processing device estimates a route for the vehicle based on a probability calculation and assumes that the road segment lies on this estimated route. This probability calculation can be based, for example, on statistical information about routes traveled by other vehicles in the past.

[0020] To determine the speed limit, the detection device also receives route information wirelessly from a remote vehicle.

[0021] Regarding route information, it is preferably intended that the route information relates to the road segment and includes a speed limit, a traffic sign, traffic signal information, curve information, traffic situation information, and / or statistical speed data. Such a speed limit can be present as such, in particular through assignment using the map above. Alternatively, the speed limit can also result from the processing of a traffic sign. Traffic signal information can be, for example, the status of a traffic light or other traffic signal system. Curve information can include, in particular, a measurement of the curve radius or similar for the road segment. Traffic situation information can include a statement about the number of vehicles on the road segment.The statistical speed data may include, for example, the average driving speed of vehicles on the road section, which has been recorded in the past and possibly over a longer period of time.

[0022] The absence of a speed limit can also be interpreted as route information. It is therefore preferred that the route information refers to the road segment and includes an indication that the segment is unrestricted, and that the detection device determines a speed limit for the unrestricted section, which is stored in a data memory for unrestricted sections. In this way, the driver can, for example, specify a desired speed for sections of highway without a speed limit, which then takes effect every time such a section is driven. This data memory can also be identical to the map memory mentioned above.

[0023] Building on this, it is preferred that the speed limit stored in the data memory be adjustable via a user interface of the vehicle and updated in the data memory after being set, and that after the vehicle's ignition is switched off, the speed limit stored in the data memory is reset to a starting value. This ensures that, in the event of a driver change, the setting made by a previous driver is not adopted by a subsequent driver.

[0024] Connecting a trailer to a motor vehicle restricts its handling and is also subject to speed limits. Therefore, it is preferable for the detection device to include a sensor for detecting a trailer connected to the motor vehicle and to adjust the speed limit accordingly. This minimizes the risk of the motor vehicle and trailer exceeding the speed limit. Alternatively or additionally, the connection of a trailer to the motor vehicle can also be detected by an electrical connection to the trailer and the motor vehicle's power supply to the trailer.

[0025] To accommodate both effective speed limiting and the driver's desired speed, the cruise control system preferably determines a target cruise control speed based on the driver's input and then determines the target cruise control acceleration based on that target speed. Thus, the cruise control system considers both the driver's input and the speed limit when determining the target cruise control acceleration.

[0026] One way to implement such a driver setting involves the driver explicitly specifying the desired cruise control speed. A preferred alternative is that the driver setting includes a target speed offset, and the cruise control target speed is based on this offset and the speed limit. In this way, the driver can specify that they want the vehicle to travel at a speed that is a certain amount above or below the speed limit.

[0027] With regard to the distance control device, it is preferably provided that it determines the distance control target acceleration in such a way that a target minimum distance to the vehicle in front is maintained.

[0028] As a rule, the vehicle's drive system is controlled with a non-zero target acceleration when a target speed, which can be determined by the speed limiter and the adaptive cruise control, does not match the vehicle's actual speed. The greater the difference between the actual and target speeds, the greater the target acceleration will be. However, it can be advantageous to provide a more nuanced approach to the target acceleration than simply "jumps." The cruise control system determines the target acceleration based on an active target acceleration profile, which defines a temporal target acceleration progression.Therefore, the target acceleration is not constant over time - specifically in relation to the time during which a non-zero target acceleration is applied - but rather it exhibits a changing profile.

[0029] Here, it is particularly advantageous that the target acceleration profile over time follows an essentially asymptotic approach to a maximum acceleration value. The acceleration value in this context refers to the absolute value of the acceleration. This approach avoids abrupt acceleration jumps and limits the maximum acceleration value.

[0030] Finally, it is preferred that the active target acceleration profile be determined from a multitude of stored target acceleration profiles, wherein the determination of the active target acceleration profile is based on a difference between the speed limit and the current actual speed of the vehicle, on the current actual speed of the vehicle, on the type of road currently being traveled on by the vehicle, and / or on an expected speed limit. Accordingly, a situation-dependent target acceleration profile can be used.

[0031] Further features and advantages of the invention will become apparent from the following description of a non-limiting embodiment, which is explained in more detail below with reference to the figures. The drawing schematically shows: Fig. 1 an embodiment of an electronic system in a motor vehicle for carrying out the method according to the invention, Fig. 2 a flowchart for an embodiment of the method according to the invention, Fig. 3 a motor vehicle with the electronic system of Fig. 1 for carrying out the method according to the invention in a first driving situation, Fig. 4 the motor vehicle of Fig. 3 in a second driving situation and Fig. 5 a target acceleration profile for use in an embodiment of the method according to the invention.

[0032] The one in Fig. The electronic system shown in 1 serves for automatic acceleration adjustment in a motor vehicle 1. Such a motor vehicle 1 is in each of the Fig. 3 and Fig. Figure 4 illustrates this. A detection device 2 of the motor vehicle 1 comprises a position sensor 3, which in this case is a GPS receiver, a camera arrangement 4, which is directed forward in the direction of travel of the motor vehicle 1, and a logic unit that processes the data received from the position sensor 3 and the camera arrangement 4. In this exemplary embodiment, and preferably, the detection device 2 also includes a distance sensor 24 for detecting the vehicle distance to a vehicle 13 traveling ahead, which is also located in the Fig. Figure 3 is shown. In the present embodiment, the detection device 2 further comprises a logic unit, which here simultaneously forms a map processing device 5, which has access to a map containing various route information stored in a map or data memory (not shown separately here). In the present embodiment, the detection device 2 further comprises a radio device 28, which can wirelessly receive route information from a stationary route control device (not shown) to determine the speed limit.

[0033] The electronic system also includes a cruise control device 6, which receives a speed limit from the detection device 2 and a driver input from an operating interface 7. The driver input consists of an offset from the speed limit, such that a speed 5 km / h above the speed limit is specified. This target speed offset is entered via an offset input 23 of the operating interface 7 and can be either positive or negative relative to the speed limit. The cruise control device 6 outputs a target cruise control acceleration to a control device 8, which in turn controls a drive device 9 of the vehicle 1 with a target drive acceleration. The drive device 9 can influence the acceleration and speed of the vehicle 1 by directly accessing the motor 10 and brakes 11 of the vehicle 1.Likewise, the cruise control device 6 receives data on vehicle kinematics from the drive device 9.

[0034] If the detection device 2 cannot determine a current speed limit from either the camera arrangement 4 or the map processing device 5, the last determined speed limit is preferably retained.

[0035] Furthermore, the electronic system includes a distance control device 12, which receives a vehicle distance to a vehicle 13 ahead, as measured here by the distance sensor 24. In this embodiment, the logic unit and the map processing device 5 (identical to it here), the cruise control device 6, the distance control device 12, and the control device 8 are formed by a processor device 17.

[0036] Both the offset input 23 mentioned above and the operating interface 7 as a whole can be implemented for input via buttons on the steering wheel of the vehicle 1. These buttons allow the electronic system mentioned above to be switched between a standby and an active state. Furthermore, the driver can override the electronic system through active intervention. This can be done via the buttons as well as via the accelerator or brake pedal of the vehicle 1. Optionally, after such active intervention, the electronic system switches to standby mode or returns to the state before the active intervention. The operating interface 7 also features a graphical display of the currently set speed limit and the target speed offset, as well as a situation-dependent warning output when the electronic system transitions to standby mode.

[0037] An exemplary driving situation of the motor vehicle 1 for the application of the method according to the invention is shown in the Fig. Figure 3 is shown. Based on this and on the aforementioned vehicle kinematic data – which it also receives – the distance control device 12 determines a target acceleration for distance control, which is transmitted to the control device 8. In the control device 8, the target acceleration for the drive is then limited to the value of the target acceleration for distance control. This limitation can optionally refer to the signed acceleration or to a specific magnitude of the acceleration.

[0038] The Fig. Figure 2 shows a sequence of events as it unfolds in the situation of Fig. 3. The camera arrangement 4 detects a traffic sign 14 and, based on this, determines a currently applicable speed limit of 50 km / h in a detection step 15. Similarly, the position sensor 3, which receives position information from navigation satellites 16, could have determined this speed limit by comparing this position information with a map stored in a map memory, which contains various route information.

[0039] The cruise control device 6 of the processor device 17 sets a cruise control target speed of 55 km / h in a speed step 18, based on the speed limit thus determined and an exemplary target speed offset of 5 km / h according to a driver input. In the same step, the distance control device 12, also formed by the processor device 17, calculates a distance control target speed. This calculation is based on the vehicle distance to the vehicle ahead 13, which the distance sensor 24 has detected. Based on this distance control target speed, the signed distance control target acceleration is then calculated in calculation step 19, and – again based on the above cruise control target speed – the also signed cruise control target acceleration is calculated.In the subsequent comparison step 20, it is checked whether the cruise control setpoint acceleration is greater than the adaptive cruise control setpoint acceleration. If so, in a distance control step 21, the control device 8 steers the drive device 9 according to the adaptive cruise control setpoint acceleration. If, on the other hand, the adaptive cruise control setpoint acceleration exceeds the cruise control setpoint acceleration, in a cruise control step 22, the control device 8 steers the drive device 9 according to the cruise control setpoint acceleration.

[0040] The calculation of the cruise control target acceleration can now be based on a target acceleration profile, which defines a target acceleration curve over time (26, 27). Examples are shown in the Fig. Figure 5 shows two such target acceleration profiles 26 and 27 over time. Both target acceleration profiles 26 and 27 have in common that the resulting cruise control target acceleration, starting from zero, assumes a final value in the manner of an asymptotic approximation. Target acceleration profile 26 applies, for example, to the case of a small difference between the speed limit and the current actual speed of vehicle 1, and a low current actual speed of vehicle 1, whereas target acceleration profile 27 applies to the case of a larger difference between the speed limit and the current actual speed of vehicle 1, and a higher current actual speed of vehicle 1.

[0041] Referring again to the Fig. 3. Instead of the detection of traffic sign 14 by the camera arrangement 4 and the determination of the speed limit based thereon, it is also possible that, according to the provisions in the Fig. In the situation shown in Figure 4, the camera arrangement 4 captures curve information 25 – that is, information about the degree of curvature of a road section to be driven on – and determines a speed limit based on this curve information. In this case, the speed limit is therefore not based on a standard, but rather results from the driving characteristics of the vehicle 1 and the "difficulty" of the curve corresponding to the curve information 25. Similarly, the position sensor 3, which receives position information from navigation satellites 16, could have determined this speed limit by comparing this position information with a map stored in a map memory, which contains various route information.

[0042] It may be that a minimum speed is specified for the cruise control device 6 and / or for the distance control device 12, below which the respective functionality is not available or only partially available.

[0043] In a first exemplary scenario, the detection device 2 detects a speed limit that is below this minimum speed. At the same time, there is no vehicle ahead within range of the distance control device 12. In this case, the cruise control device 6 accelerates the vehicle 1 up to the minimum speed and then switches the electronic system to standby mode.

[0044] A second exemplary scenario corresponds to the first scenario above, with the difference that, due to a positive target speed offset, the cruise control target speed determined by the cruise control device 6 is above the minimum speed. In this case, the electronic system remains active until – for example, due to a reduction in the target speed offset – the cruise control target speed falls below the minimum speed, at which point the procedure is the same as in the first scenario.

[0045] In a third exemplary scenario, a vehicle 13 ahead is within range. Here, a distinction is again made as to whether the vehicle 1 has a so-called "stop-and-go" functionality. This allows the distance control device 12 to regulate the distance of the vehicle 1 to the vehicle 1 ahead without having to maintain a minimum speed.

[0046] Therefore, if in the third scenario the vehicle 1 does not have "stop-and-go" functionality, the electronic system switches to standby mode as soon as the minimum speed, based on the distance control device 12, is undershot. If the vehicle 1 has "stop-and-go" functionality, the electronic system remains active as long as the vehicle 13 ahead is within range of the distance sensor 24. Only when the vehicle 13 ahead, for example, due to a deviating route or exceeding the speed limit, moves outside the range of the distance sensor 24, does the electronic system switch to standby mode.

Claims

[1] Method for automatic acceleration adjustment in a motor vehicle (1), wherein a detection device (2) determines a speed limit applicable to a road section, wherein a cruise control device (6) determines a cruise control setpoint acceleration based on the speed limit, and wherein a control device (8) controls a drive device (9) of the motor vehicle (1) with a drive setpoint acceleration based on the cruise control setpoint acceleration, wherein a distance control device (12) determines a distance control setpoint acceleration based on a detected vehicle distance to a vehicle ahead (13), and the drive setpoint acceleration is limited by the distance control setpoint acceleration such that the drive setpoint acceleration remains below the distance control setpoint acceleration. characterized by , that the detection device (2) comprises a radio device (28) which wirelessly receives route information from a stationary route device for determining the speed limit, wherein the cruise control device (6) determines the cruise control target acceleration based on an active target acceleration profile, wherein the target acceleration profile defines a target acceleration profile over time (26, 27), wherein the detection device (2) comprises a map processing device (5) which reads route information from a map for the road segment in order to determine the speed limit, wherein the detection device (2) for determining the speed limit wirelessly receives route information from a remote vehicle, and wherein the map processing device (5) estimates a route to be travelled by the motor vehicle based (1) on a probability calculation and the road segment lies on this estimated route. [2] Method according to claim 1, characterized by , that the detection device (2) determines a speed limit which applies to a section of road currently being traveled by the motor vehicle (1) and / or that the detection device (2) determines a speed limit which applies to a section of road to be traveled in the future within the sight range of the motor vehicle (1) and / or a section of road to be traveled in the future outside the sight range of the motor vehicle (1). [3] Method according to claim 1 or 2, characterized by , that the detection device (2) comprises a camera arrangement (4) which optically detects route information for determining the speed limit. [4] Method according to any one of claims 1 to 3, characterized by , that the route information relates to the road segment and includes a speed limit, a traffic sign (14), traffic signal information, a curve information (25), traffic situation information and / or statistical speed data. [5] Method according to any one of claims 1 to 4, characterized by , that the route information relates to the road segment and includes a designation of the road segment as unrestricted and that the detection device (2) determines a speed limit for the unrestricted road segment which has been stored in a data storage device for unrestricted road segments. [6] Method according to claim 5, wherein the speed limit stored in the data storage can be set via an operating interface (7) of the motor vehicle (1) and is updated in the data storage after setting, and wherein after switching off the ignition state of the motor vehicle (1) the speed limit stored in the data storage is reset to a starting value. [7] Method according to any one of claims 1 to 6, characterized by , that the detection device (2) has a sensor device for detecting a trailer connected to the motor vehicle and, in the case of a trailer connected to the motor vehicle (2), adjusts the speed limit. [8] Method according to any one of claims 1 to 7, characterized by , that the cruise control device (6) determines a cruise control setpoint speed based on a driver input and determines the cruise control setpoint acceleration based on the cruise control setpoint speed. [9] Method according to claim 8, characterized by , that the driver's input includes a target speed offset and the cruise control target speed is based on the target speed offset and the speed limit. [10] Method according to any one of claims 1 to 9, characterized by , that the distance control device determines the distance control target acceleration in such a way that a target minimum distance to the vehicle in front (13) is maintained. [11] Method according to claim 1, characterized by , that the temporal target acceleration profile (26, 27) provides for an essentially asymptotic approach to a maximum acceleration amount as time increases. [12] Method according to claim 1 or 11, characterized by, that the active target acceleration profile is determined from a multitude of stored target acceleration profiles, wherein the determination of the active target acceleration profile is based on a difference between the speed limit and the current actual speed of the motor vehicle (1), on the current actual speed of the motor vehicle (1), on the type of road currently being traveled by the motor vehicle (1) and / or on an expected speed limit.

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