Method and device for controlling the speed of a motor vehicle

Abstract

Method for controlling the speed of a motor vehicle, wherein the control is based on a predetermined setpoint for the vehicle speed, wherein this setpoint is adjusted depending on environmental conditions, and wherein the method comprises the following steps: Determine whether and, if so, at what distance from the current position of the motor vehicle a situation with an increased risk of reduced traffic speed is to be expected on a planned route, whereby this determination is made at least partially on the basis of traffic data available for the past; and Adjusting the target value for the vehicle speed underlying the control system depending on the result of this determination, wherein the adjustment of the target value for the vehicle speed is carried out taking into account an initial driver input, wherein this driver input defines at least one driver preference regarding the effects achieved by this adjustment; characterized in that In a case where it is determined that and at what distance from the current position of the motor vehicle a situation with an increased risk of reduced traffic speed is to be expected on the intended route, the driver is offered a selection of several different alternative target values ​​for the vehicle speed, whereby if the driver makes a second driver input by selecting one of the proposed alternative target values, the adjustment of the target value for the vehicle speed underlying the control is carried out on the basis of the selected alternative target value.

Description

[0001] The invention relates to a method and a device for controlling the speed of a motor vehicle.

[0002] The invention relates in particular to a method and a device for dynamically readjusting the current setpoint of the vehicle speed in a cruise control system, in an adaptive speed or distance control system, or in any system for partially or fully automated control of the vehicle speed.

[0003] Various systems for controlling the speed of a motor vehicle are known in the prior art. The basic system is usually referred to as cruise control and involves simple speed control using the engine, accelerating the vehicle if necessary, and allowing the driver to easily set the desired speed using a corresponding button located on the steering wheel or the vehicle's center console. Adaptive cruise control is additionally capable of controlling the brakes and monitoring the traffic ahead in order to maintain a specific distance to a vehicle in front or to initiate an abrupt reduction in speed if the distance to the vehicle ahead becomes too small.

[0004] Furthermore, adaptive cruise control systems for stop-and-go traffic and / or traffic jam assist systems are known, capable of bringing the vehicle to a standstill and restarting it depending on the surrounding traffic. Additionally, assistance systems are known that automatically adjust the vehicle speed based on upcoming speed limits. Future generations of autonomous vehicles will require comparable systems for controlling vehicle speed.

[0005] German patent DE 10 2014 203 296 A1 discloses, among other things, a speed control system in which a standard speed control function is executed when heavy traffic is detected. Under conditions of low traffic density, the powertrain variables are updated.

[0006] From DE 10 2014 204 206 A1, among other things, a method for optimizing the energy consumption of a vehicle is known, wherein the energy consumption for several conceivable speed profile trajectories is compared in order to identify the profile for an optimal speed.

[0007] From US 8 620 569 B2, among other things, a control device is known in which a speed pattern optimized with regard to low fuel consumption is calculated and a corresponding adjustment of the vehicle control is made based on this speed pattern.

[0008] In general, the systems described above regulate the vehicle speed based on target values ​​(e.g., for the average vehicle speed or the distance to the vehicle in front) or activate special operating modes when certain vehicle speed thresholds are reached (e.g., a traffic jam assist device can be activated when the driving speed on a motorway is below 50 km / h).

[0009] However, situations can arise, particularly on longer journeys, where an intelligent, dynamic, and potentially automatic adjustment of the target vehicle speed by the cruise control system is desirable. For example, a driver who has set a desired vehicle speed of 120 km / h on the motorway might encounter a traffic accident or congestion 50 km away. It usually takes some time for the situation (e.g., the accident-related traffic disruption) to be resolved or for normal traffic conditions to return. In such cases, it is disadvantageous for the driver to be unaware of the traffic situation or the resulting delay.-disruption according to the original plan, as this only causes stress and frustration for the driver, whereas a reduction in fuel consumption could have been achieved by reducing the vehicle speed earlier.

[0010] Current approaches include, among other things, the suggestion of alternative routes by the respective navigation system (e.g. leaving the motorway and driving on a correspondingly fuel-saving route).

[0011] From DE 100 28 661 A1, among other things, a method for the sensible use of traffic jam-related delays is known, whereby an interesting waypoint or guidance to such a waypoint is suggested to the user if the determined delay times on the route to the destination are greater than or equal to the time required to reach the interesting waypoint.

[0012] German patent DE 10 2015 005 902 A1 discloses, among other things, a method for operating a motor vehicle and a traffic light assistant, wherein a traffic light sequence is determined depending on a calculated relative position of the motor vehicle with respect to a traffic light arranged in front of the motor vehicle in the direction of travel, as well as depending on the calculated traffic flow, and wherein at least one functional unit of the motor vehicle is controlled depending on the calculated traffic light sequence. The aim is to enable fuel-efficient and comfortable passage through a traffic light.

[0013] German patent DE 10 2013 011 538 A1 discloses, among other things, a method for operating a longitudinal driver assistance system of a motor vehicle, whereby a target speed deviating from a desired speed specified by the driver is determined, taking into account route information describing the route to a destination and a destination arrival time, and set as the new desired speed. This setting can be made either after confirmation by the driver or immediately. In particular, whenever new route information is available, it can be checked whether an adjustment of the currently set desired speed is necessary and / or advisable.

[0014] From DE 10 2008 035 944 A1, inter alia, a method for optimizing the driving operation of a motor vehicle is known, wherein several different route parameters, which are characteristic for a route profile of a determined route between the vehicle's starting point and destination, as well as at least one driving condition for the determined route, are determined, and wherein a target driving speed along the determined route is determined taking into account the route parameters and the driving condition. Furthermore, the route is divided into segments based on the route parameters and / or the driving condition.

[0015] From DE 10 2013 009 945 A1, a generic method and a device for speed control of a drive train of a motor vehicle are known, in which a speed profile for a route to be travelled is obtained taking into account dynamic data obtained from previous travel on the route, and in which the vehicle can be controlled according to this speed profile.

[0016] From DE 10 2014 215 673 A1 a driver assistance system is known in which locations with reduced target speed are predicted and taken into account, whereby the locations with reduced speed are static, e.g. speed limits in towns or construction sites, so that their length is fixed in advance.

[0017] From DE 10 2007 043 602 A1 a method for adjusting the speed of a vehicle in front of a signaling system is known; this concerns an optimization of the vehicle approach in the immediate vicinity of the signaling system.

[0018] From DE 10 2005 045 891 B3, a speed optimization strategy for a vehicle, primarily aimed at fuel efficiency, is known, in which, among other things, the traffic flow is taken into account.

[0019] From DE 10 2012 212 065 A1 a so-called traffic jam assistant is known, which aims to optimize the control of the vehicle in a traffic jam.

[0020] For further information on the state of the art, reference is made to US 2014 / 0222259 A1 as an example.

[0021] It is an object of the present invention to provide a method and a device for controlling the speed of a motor vehicle which allows for individual consideration of expected traffic situations with reduced traffic speed, such as traffic jams, while reducing the stress load on the driver.

[0022] This problem is solved by the method according to the features of independent claim 1 or the device according to the features of dependent claim 10.

[0023] In an inventive method for controlling the speed of a motor vehicle, the control is based on a predetermined setpoint for the vehicle speed, whereby this setpoint is adjusted depending on environmental conditions. The method comprises the following steps: - Determine whether and, if so, at what distance from the current position of the vehicle a situation with an increased risk of reduced traffic speed is to be expected on a planned route, whereby this determination is made at least partially on the basis of traffic data available for the past; and - Adjusting the target value for vehicle speed underlying the control system depending on the result of this determination.

[0024] According to one embodiment, the determination step also includes taking into account situations in which a traffic obstruction on a planned route does not yet exist, but is expected to occur in the future based on data available from the past.

[0025] The invention also includes, in particular, the concept of adjusting the setpoint underlying the speed control based on traffic forecasts using mass data (“Big Data”) or predictive analysis, wherein a speed reduction carried out to avoid congestion is not made with regard to a traffic jam already existing at the current time in a specific area, but to avoid a traffic jam which is highly likely to occur in the near future based on data available for the past in the area in question (e.g. due to peak traffic times, roadworks, etc.).

[0026] Such data can be derived, for example, from data collected in the past for the route in question and processed on a central server or in cloud storage. This latter analysis can even be performed before the journey begins, as soon as the route has been programmed into the navigation system, provided that sufficient information has been collected for the selected route in the past.

[0027] The invention is based in particular on the concept of equipping a system for partially or fully automated vehicle speed control with the ability to intelligently adjust the speed in light of known or predicted future traffic situations with reduced traffic speeds (e.g., an accident in 20 km), instead of following a speed setpoint specified by the driver. This reduces stress for the driver resulting from stop-and-go traffic or traffic jams and also avoids unnecessary fuel consumption.

[0028] The invention further includes the concept of automatically modifying the respective speed setpoint within certain limits in a speed control system operating on the basis of speed setpoints, taking into account current and predicted traffic information.

[0029] The invention includes, firstly, the detection of driving situations that justify an adjustment (i.e., an "override") of the current target value of the vehicle speed. Secondly, the invention includes a suitable strategy for adjusting the target value for the vehicle speed.

[0030] According to the invention, the target value for the vehicle speed is adjusted taking into account a first driver input, whereby this driver input determines at least one preference of the driver with regard to the effects achieved by this adjustment.

[0031] According to the invention, the driver can thus be given the option of selecting from different optimization criteria, whereby the driver or vehicle occupant can determine whether, at a given time, arrival time, fuel savings, or avoiding stop-and-go traffic is of greater importance. This takes into account that different optimization criteria generally result in different characteristic journey profiles, whereby different priorities may exist depending on the individual driver or vehicle occupant and their personal time management.

[0032] According to one embodiment, the aforementioned driver input weights the relevance of at least one, in particular all, of the following parameters when adjusting the target value for the vehicle speed: the reduction in driver stress achieved by the adjustment, the fuel savings achieved by the adjustment, and the shift in the vehicle's arrival time at the destination caused by the adjustment.

[0033] According to the invention, the adjustment of the target value for the vehicle speed can be carried out, in particular with regard to reducing the stress load on drivers or vehicle occupants, whereby, for example, a vehicle standstill or a stop & go situation can be avoided under all circumstances.

[0034] According to the invention, the adjustment of the setpoint for the vehicle speed underlying the control is based on a second driver input, in which the driver makes a selection from a plurality of different suggested setpoints for the vehicle speed if it has been determined that and at what distance from the current position of the motor vehicle a situation with an increased risk of reduced traffic speed on the intended route is to be expected, whereupon the driver was offered a plurality of different alternative setpoints for the vehicle speed to choose from.

[0035] According to one embodiment, the target value of the vehicle speed is adjusted by specifying a limit value for the vehicle speed that must not be undercut and / or a limit value for the vehicle speed that must not be exceeded.

[0036] According to one embodiment, at least one limit value is selected depending on the current target value for the vehicle speed.

[0037] According to one embodiment, the determination step further includes estimating the time period until the situation with increased risk of reduced traffic speed is resolved.

[0038] According to one embodiment, this estimate is based on traffic data available from the past.

[0039] According to one embodiment, depending on the result of the investigation, an automatic suggestion is made to the driver to interrupt the journey.

[0040] According to the invention, the driver can be advised to interrupt the journey, for example, in the form of a break, a meal, or shopping, if such opportunities exist along the route and no other optimization is possible. For instance, if a serious traffic jam caused by an accident cannot be avoided even by reducing the vehicle's speed, the driver can be advised to take a break and engage in more productive activities (eating, shopping, resting, etc.) to avoid otherwise wasting time in the traffic jam.

[0041] The invention further relates to a device for controlling the speed of a motor vehicle, wherein the control is based on a predetermined setpoint for the vehicle speed, this setpoint being adjusted depending on ambient conditions, and wherein the device is configured to carry out a method with the features described above. For advantages and preferred embodiments of the device, reference is made to the preceding descriptions in connection with the method according to the invention.

[0042] Further embodiments of the invention can be found in the description and the dependent claims.

[0043] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying figure.

[0044] The only Fig. Figure 1 shows a flowchart to illustrate a possible sequence of the method according to the invention in one embodiment.

[0045] Although the following refers to motorways or expressways as examples, the disclosure is in principle applicable to any traffic situation.

[0046] The following section describes the procedure for detecting traffic situations according to the invention that justify an adjustment of the current target vehicle speed. This involves monitoring areas on a specific route selected by the driver (e.g., a motorway section entered using the navigation system) that could negatively impact the vehicle speed (e.g., accidents, traffic jams, roadworks, etc.). Two data and information sources can be used for this purpose. Firstly, current traffic data (e.g., TMC) with information about traffic jams, accidents, etc., can be accessed. Secondly, traffic data with information about areas where there is an increased risk of reducing traffic speed can be used, such as...The route can be derived from data collected in the past for the route in question and processed on a central server or in cloud storage. This latter analysis can be performed before the journey begins, as soon as the route has been programmed into the navigation system, provided that sufficient information has been collected for the selected route in the past.

[0047] The following describes a strategy according to the invention for adjusting the target value of the vehicle speed according to one embodiment of the invention: The driver can initially input their own preferences regarding arrival time, stress level, and fuel savings into the system in case an adjustment of the target vehicle speed is necessary. If a situation is detected that causes a reduction in traffic speed on the upcoming route, and if the cruise control system is activated, the device according to the invention automatically adjusts the target vehicle speed after notifying the driver accordingly. According to the invention, one or more alternative target vehicle speeds can be calculated based on the following parameters and rules: a) According to the invention, it is first possible to estimate how long a situation with reduced traffic speed will last (e.g., how long it takes for a traffic jam of 3 km length to clear). This can be done based on historical data (by means of predictive analysis) or simply using a lookup table, which contains estimates for different traffic speed reduction scenarios (e.g., for accidents, traffic jams, or slow-moving traffic of 3 km, 7 km, or 10 km length). b) The vehicle should reach the area in question at reduced traffic speed after the estimated time period described above if the cause of the reduced traffic speed is highly likely to have been partially or completely resolved. The aim here is to reduce the driver's stress and frustration by delaying or avoiding exposure to the traffic jam or stop-and-go situation ("stress reduction parameter"). c) Preferably, an assessment is made of the impact of reducing the target value for the vehicle speed on the driver's original schedule; this may take into account that the driver may need to arrive at the destination within a certain time window ("arrival time parameter"). d) Furthermore, it is preferable to estimate the influence of reducing the target speed for the vehicle speed on fuel consumption and emission values ​​(“fuel consumption parameters”). e) Furthermore, the device is preferably capable of continuously readjusting the target value for the vehicle speed in light of new information regarding the area of ​​traffic speed reduction. For example, if the traffic situation improves, the target value for the vehicle speed can be reset to its original value. Conversely, if the traffic situation deteriorates, the device can perform a second reduction of the target value for the vehicle speed. In some cases, the target value for the vehicle speed may also be increased if the arrival time parameter is particularly critical. f) Preferably, the target value for the vehicle speed is maintained within a predetermined range. This means that the vehicle speed preferably does not fall below a minimum value and does not exceed any applicable local speed limits. In particular, it may be required that the vehicle speed remains within a predetermined tolerance range around the original target values.

[0048] Several methods can be used to select suitable target values ​​for the vehicle speed. Firstly, optimization algorithms can be applied to reduce driver stress, arrival time, and fuel consumption (according to the parameters mentioned above). Secondly, the vehicle speed can be automatically adjusted. In this case, the most favorable alternatives can also be suggested to the driver.

[0049] In embodiments of the invention, even in the case of an extreme situation - such as a particularly serious accident with several hours of traffic delay - the driver can be offered a break in order to use the relevant period of time in another way (e.g. to have a meal or to go shopping) if no other suitable optimization is available.

[0050] In the following, a specific example of implementation will be presented with reference to the one in Fig. The flowchart shown in section 1 describes the process, whereby the numerical values ​​given below are merely examples and are not based on concrete data regarding fuel savings. The delay caused by a traffic jam is not taken into account; rather, the focus is on when the vehicle reaches the traffic jam.

[0051] In step S10, a driver programs a route (e.g., 200 km long) using their navigation system. In step S20, the driver specifies that the arrival time is not critical, fuel savings are particularly important, and stress levels are a parameter of medium importance.

[0052] In step S30, the driver activates a cruise control system on the motorway, selecting a target value for the vehicle speed of 140 km / h.

[0053] In step S40, the device according to the invention begins monitoring areas with reduced traffic speed and, after some time, detects a major traffic obstruction (e.g., "7 km of slow-moving traffic") at a distance of 70 km from the current location of the vehicle. In step S50, based on historical data or a reference table, it is estimated that this type of traffic jam will clear up after an average of 30 minutes.

[0054] In step S60, alternative target values ​​for the vehicle speed are calculated and suggested to the driver, with an estimate of the impact on the stress parameter, the arrival time parameter, and the fuel consumption parameter. The following suggestions are made in the example: (i) Maintaining a vehicle speed of 140 km / h: Delay of 0 minutes, fuel savings of 0%, high stress level (as traffic congestion is likely to still exist at the time of arrival); (ii) Reduction of vehicle speed to 120 km / h: Delay of 5 minutes, fuel savings 7%, medium stress level; (iii) Reducing vehicle speed to 100 km / h: Delay of 12 minutes, fuel savings of 15%, low stress.

[0055] Although the present example is limited to three alternatives, any further scenarios (e.g. with target speeds at intervals of 5 km / h) can be calculated.

[0056] In step S70, the driver selects, for example, alternative (iii). In the case of autonomous driving mode and if the parameters entered by the driver in step S20 are known, a system-based or automatic selection of, for example, alternative (iii) can also occur.

[0057] In step S80, the device according to the invention reduces the target value for the vehicle speed to 100 km / h. In the case of an autonomously driving vehicle, a change to the right lane is also highly likely to occur.

[0058] In step S90, the device according to the invention continuously monitors the traffic jam. After a driving time of 40 minutes, the device receives information that the traffic jam has cleared. In step S100, the driver is notified accordingly, whereupon the original target value for the vehicle speed of 140 km / h is set.

Claims

[1] Method for controlling the speed of a motor vehicle, wherein the control is based on a predetermined setpoint for the vehicle speed, wherein this setpoint is adjusted depending on environmental conditions, the method comprising the following steps: Determine whether and, if so, at what distance from the current position of the motor vehicle a situation with an increased risk of reduced traffic speed is to be expected on a planned route, whereby this determination is based at least partially on historical traffic data; and Adjusting the target value for the vehicle speed underlying the control system depending on the result of this determination, wherein the adjustment of the target value for the vehicle speed is carried out taking into account an initial driver input, whereby this driver input establishes at least one driver preference regarding the effects achieved by this adjustment; characterized by , that In a case where it is determined that and at what distance from the current position of the motor vehicle a situation with an increased risk of reduced traffic speed is to be expected on the intended route, the driver is offered a selection of several different alternative target values ​​for the vehicle speed, whereby if the driver makes a second driver input by selecting one of the proposed alternative target values, the adjustment of the target value for the vehicle speed underlying the control is carried out on the basis of the selected alternative target value. [2] Method according to claim 1, characterized by , that the step of determining includes taking into account situations in which a traffic obstruction on a planned route does not currently exist, but is expected to occur in the future based on data available from the past. [3] Method according to claim 1 or 2, characterized by , that the first driver input weights the relevance of at least one, in particular all, of the following parameters when adjusting the target value for the vehicle speed: - the reduction in driver stress achieved through the adjustment, - fuel savings achieved through the adjustment; - the change in the arrival time of the vehicle at the destination caused by the adjustment. [4] Method according to any one of claims 1 to 3, characterized by , that the adjustment of the target value of the vehicle speed is carried out by specifying a limit value for the vehicle speed that must not be undercut and / or a limit value for the vehicle speed that must not be exceeded. [5] Method according to claim 4, characterized bythat this limit value is selected depending on the current target value for the vehicle speed. [6] Method according to any one of the preceding claims, characterized by that the step of determining further includes the estimation of a time period until the situation with increased risk of reduced traffic speed is lifted. [7] Method according to claim 6, characterized by that this estimate is based on traffic data available from the past. [8] Method according to any one of the preceding claims, characterized by , that depending on the result of the investigation, an automatic suggestion is made to the driver to interrupt the journey. [9] Method according to any one of the preceding claims, characterized by, that several situations with an increased risk of reduced traffic speed are monitored and the target value of the vehicle speed is adjusted depending on the result of this monitoring. [10] Device for controlling the speed of a motor vehicle, wherein the control is based on a predetermined setpoint for the vehicle speed, wherein this setpoint is adjusted depending on environmental conditions, characterized by that the device is configured to perform a method according to one of the preceding claims.

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