SE542810C2

SE542810C2 - A method and an apparatus for selecting a gear in a motor vehicle approaching an intersection

Info

Publication number: SE542810C2
Application number: SE1850648A
Authority: SE
Inventors: Afram Kourie; Anders Björkman; Frank Mohr; Marcus Engman
Original assignee: Scania Cv Ab
Priority date: 2018-05-29
Filing date: 2018-05-29
Publication date: 2020-07-14
Also published as: DE102019002941B4; BR102019010083A2; DE102019002941A1; SE1850648A1

Abstract

A method for automatically selecting a gear in a powertrain of a motor vehicle, comprising:- determining (101) that the motor vehicle approaches an intersection,- acquiring (102) information relating to traffic conditions in the intersection,- based on the acquired information relating to the traffic conditions, selecting (103) a target gear, which target gear is to be engaged when accelerating the motor vehicle in connection with the intersection.

Description

A method and an apparatus for selecting a gear in a motor vehicle approaching an intersection TECHNICAL FIELD OF THE INVENTION The present invention relates to a method and an apparatus for automatically selecting a gear in a powertrain of a motor vehicle. The invention also relates to a computer program, a computerreadable medium and a motor vehicle.

BACKGROUND AND PRIOR ART Under certain circumstances, when a driver of a motor vehicle reduces the vehicle speed by means of a brake pedal, the powertrain of the motor vehicle is disengaged by e.g. engaging a neutral gear or by depressing a clutch. Successive downshifting, in which each gear is only engaged for a short amount of time, is thereby avoided. When the driver depresses the accelerator pedal again, a gear that enables the motor vehicle to be quickly accelerated is usually engaged.

However, in some cases, the current traffic situation prevents the motor vehicle from being quickly accelerated. This may e.g. be the case when the motor vehicle approaches a heavily trafficked intersection, in which acceleration of the motor vehicle has to be adapted to surrounding traffic. In such situations, only limited acceleration may be possible.

SUMMARY OF THE INVENTION It would be desirable to achieve a method and an apparatus for automatically selecting a gear in a powertrain of a motor vehicle, which method and apparatus enable an, in at least some aspect, improved gear selection in connection with intersections. In particular, it would be advantageous to provide such a method and apparatus that on one hand provide an improved drivability, and on the other hand provide a reduced fuel consumption and noise level when possible.

To better address these concerns, a method and an apparatus as defined in the independent claims are provided.

According to one aspect, a method for automatically selecting a gear in a powertrain of a motor vehicle is provided. The method comprises: - determining that the motor vehicle approaches an intersection, - acquiring information relating to traffic conditions in the intersection, - based on the acquired information relating to the traffic conditions, selecting a target gear, which target gear is to be engaged when accelerating the motor vehicle in connection with the intersection.

According to another aspect, an apparatus configured for automatically selecting a gear in a powertrain of a motor vehicle is provided. The apparatus is configured to: - determine that the motor vehicle approaches an intersection, - acquire information relating to traffic conditions in the intersection, - based on the acquired information relating to the traffic conditions, select a target gear, which target gear is to be engaged when accelerating the motor vehicle in connection with the intersection.

The method and the apparatus according to the invention enable an evaluation of the traffic situation in an intersection prior to entering, and select a gear that is deemed suitable with regard to the current traffic situation. The target gear should be a gear that can provide a desired degree of acceleration in the intersection. For example, if there is no traffic present in the intersection, it is possible to enter and exit without high acceleration, and a relatively high gear may therefore be selected. If there is traffic present, but the traffic conditions are such that it will be possible to enter and exit the intersection if the motor vehicle can be quickly accelerated, a low gear providing high acceleration may be selected. If the traffic conditions are such that it is impossible to enter the intersection regardless of acceleration ability, fuel consumption and low noise may be prioritized and a relatively high gear may be selected. Thus, the method and apparatus according to the invention provide improved possibilities to enter and exit the intersection with an acceleration adapted to the current traffic situation. The fuel consumption and the drivability may thereby be improved.

In particular, but not exclusively, the method and the apparatus according to the invention are suitable for use in a heavy goods vehicle, such as a truck or a bus.

Preferred embodiments of the invention are disclosed in the dependent claims.

It will be appreciated that all the embodiments described with reference to the method aspect of the present invention are applicable also for the apparatus aspect of the present invention. That is, the apparatus may be configured to perform any one of the method steps of the described embodiments.

Other advantageous features as well as advantages of embodiments of the present invention will appear from the following description.

DEFINITIONS By a motor vehicle is herein intended a motor vehicle which is powered by an internal combustion engine and/or by an electric motor. The motor vehicle may be configured to be driven by a driver or to be driven autonomously.

By an intersection is herein intended an at-grade intersection, such as a roundabout or a crossroad, where roads going in different directions meet.

By accelerating the motor vehicle is herein intended actively increasing a vehicle speed of the motor vehicle by means of the powertrain of the motor vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will in the following be further described by means of example with reference to the appended drawings, wherein Fig. 1 is a flow chart showing a method according to an embodiment of the invention, Fig. 2 schematically illustrates an exemplary driving situation, and Fig. 3 schematically shows an electronic control unit forming part of an apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION A method for automatically selecting a gear in a powertrain of a motor vehicle according to an embodiment of the invention is schematically illustrated in fig. 1. Optional steps are marked with dashed lines.

In a step 101, it is determined that the motor vehicle approaches an intersection.

In a step 102, information relating to traffic conditions in the intersection is acquired. This information may include information about surrounding vehicles or other road users in or in the vicinity of the intersection. The information is preferably acquired continuously, e.g. at a preset rate.

In a step 103, based on the acquired information relating to the traffic conditions, a target gear is selected, which target gear is to be engaged when accelerating the motor vehicle in connection with the intersection, i.e. when a driver of the motor vehicle depresses an accelerator pedal, or when the vehicle speed is otherwise increased by means of the powertrain. The target gear should be a gear that may provide a necessary or possible acceleration in the intersection depending on the traffic conditions. Of course, apart from the traffic conditions, factors relating to vehicle dynamics, e.g. a vehicle mass, a road gradient and a powertrain configuration, should preferably also be taken into account when selecting the target gear.

The step 101 of determining that the motor vehicle approaches an intersection may comprise using positioning information and map data. The map data may be obtained from digital maps and the positioning information may e.g. be GPS (global positioning system) information. The positioning information may be used to determine the location of the motor vehicle relative to the map data. Various present-day cruise control systems use map data and positioning information. Such systems may then provide the map data and positioning information required for the method according to the present invention, thereby minimising the additional complexity involved in determining that the motor vehicle approaches an intersection. That the motor vehicle approaches an intersection may also be determined based on information received from another vehicle. It may also be retrieved from positioning information and road information stored previously on board, or from information obtained from traffic systems related to the expected travelling route.

The step 101 of determining that the motor vehicle approaches an intersection may also comprise using data provided from at least one sensor provided in or on the motor vehicle. This may be e.g. data from a camera, a radar or a navigation sensor. Furthermore, information related to driving operations may be used for determining that the motor vehicle approaches an intersection. For example, it may be detected that the clutch is being depressed, that the foot brake is operated and/or that a direction indicator is turned on. This information may be combined with data from e.g. a camera or a navigation sensor to determine that the motor vehicle approaches an intersection.

The step 102 of acquiring information relating to traffic conditions in the intersection may comprise sensing of traffic conditions using at least one sensor provided in or on the motor vehicle. The at least one sensor may e.g. be a radar, a lidar, a camera, a microphone, or a combination of several such sensors. Sensors are commonly provided on motor vehicles for other purposes, and using sensor data from those sensors is therefore a cost efficient way of acquiring traffic information. Moreover, the above mentioned sensors, in particular in combination, can provide accurate information relating to traffic conditions in the intersection.

The information relating to traffic conditions in the intersection may also be acquired at least partly using e.g. vehicle-to-vehicle communication or be provided by from a central node communicating with the motor vehicle, or from a traffic surveillance system or similar. It is possible to use a combination of sensors and communication systems to get a better overview of the traffic situation in the intersection.

The information about traffic conditions may include information about a presence of at least one relevant object in a vicinity of the intersection, and at least one of a position, a speed and a direction of motion of the at least one relevant object. The method may in this case comprise assessing whether at least one relevant object, such as another motor vehicle, or another road user, is present in the vicinity of the intersection, and determining at least a position and a speed of the at least one relevant object. By taking at least one of, and preferably all of, the position, the speed and the direction of motion of relevant objects, an estimation of a possible/necessary acceleration by the motor vehicle in the intersection is facilitated, and thereby also the selection of the target gear.

If the information relating to traffic conditions is acquired by means of sensing, the sensing of traffic conditions may comprise detecting at least one relevant object in a vicinity of the intersection, sensing a gap to the at least one relevant object from the motor vehicle, and sensing a relative velocity of the at least one relevant object with respect to the motor vehicle. The gap may in this case be determined either in terms of distance or time.

Sensing of these variables enables a fast and accurate calculation of possible/necessary acceleration in the intersection.

The step 103 of selecting the target gear may comprise: - determining a target acceleration for the motor vehicle in connection with the intersection based on at least the acquired information relating to traffic conditions, and - selecting the target gear based on the determined target acceleration.

Thus, the target gear is the gear at which the powertrain of the motor vehicle is able to accelerate the motor vehicle with the target acceleration. By determining a target acceleration, a proper selection of the target gear can be made. The target acceleration may be determined as a numerical value or range.

The target acceleration may further be determined based on at least a current performance mode of the motor vehicle. The performance mode may be e.g. economical mode, standard mode, or power mode. The performance mode may usually be selected by the driver and controls if e.g. fuel economy, driving comfort or available power should be prioritised during driving. By determining the target acceleration based on the performance mode, an adaptation to driver preferences is possible. For example, it the driver has selected the economical mode, a lower target acceleration and a higher target gear may be set than if the driver has selected the power mode.

The step 103 of selecting the target gear may further comprise: - based on at least the acquired information relating to traffic conditions, evaluating whether it will be possible to enter the intersection without stopping the motor vehicle, wherein the target gear is selected based on the evaluation.

A suitable target gear may thereby be selected based on whether the motor vehicle has to come to a complete stop or not in the intersection. This may affect the acceleration needed to enter the intersection and is therefore relevant for the gear selection. If the motor vehicle has to come to a complete stop, a relatively high preset default target gear may be selected, providing relatively low ability to accelerate, low fuel consumption and low noise. If it is determined that it is possible to enter the intersection without stopping the motor vehicle, a relatively low gear providing a higher ability to accelerate may be selected.

The method may preferably comprise the step 104 of: - engaging the selected target gear before entering the intersection.

A suitable position or point in time for engaging the selected target gear may be determined at least partly based on the traffic conditions in the intersection. The selected target gear may also be engaged e.g. when a brake is released or when a request for acceleration is received. The motor vehicle may, upon engagement of the target gear, be accelerated with the selected target gear engaged in a gearbox of the powertrain.

The powertrain may be disengaged during the selection of the target gear. In other words, the motor vehicle may be coasting (or being braked) without mechanical connection enabling power transfer between the engine and drive wheels of the motor vehicle. This may be achieved by depressing the clutch, or by setting the gearbox to a neutral position, i.e. by selecting a neutral gear.

Disengaging the powertrain when approaching the intersection avoids successive downshift that affect the driving comfort of the motor vehicle.

EXAMPLE An exemplary driving situation is schematically illustrated in fig. 2. In the exemplary driving situation, a motor vehicle 1 equipped with an apparatus 2 for automatically selecting a gear according to an embodiment of the invention, and sensors in the form of cameras, radars and a navigation sensor, is travelling on a road 3 toward an intersection in the form of a roundabout 4. A driver of the motor vehicle 1 depresses the brake pedal. Consequently, the motor vehicle 1 slows down and the powertrain is disengaged. From the depression of the brake pedal and from other available sources of information as described above, it is in the step 101 detected that the motor vehicle 1 approaches the roundabout 4. In the step 102, as the motor vehicle comes closer to the roundabout 4, the cameras and the radars are used to continuously acquire information relating to traffic conditions in the roundabout 4. In the present case, another motor vehicle 5 is approaching the roundabout 4 from the left. The gap to this vehicle 5 and its relative velocity are determined based on data from at least some of the above mentioned sensors. Based on the determined gap and relative velocity of the vehicle 5, it is in step 103 estimated which acceleration is needed to enter into the roundabout 4. This estimation is typically carried out continuously as the motor vehicle 1 approaches the roundabout 4.

If the determined gap is small and the relative velocity of the approaching vehicle 5 is high, it may be deemed impossible to enter into the roundabout 4 ahead of the approaching vehicle 5 regardless of the acceleration of the motor vehicle 1. If the motor vehicle 1 has to come to a stop before entering the roundabout 4, a target gear is selected as a relatively high preset default gear in the step 103, assuming that the motor vehicle will enter the roundabout 4 after the approaching vehicle 5, whereby only a slow acceleration is needed. Also if the motor vehicle 1 does not need to come to a full stop, but need to be slowed down to enter into the roundabout 4 after the vehicle 5, a relatively high target gear may be selected. The selection of target gear may also depend on the performance mode of the motor vehicle as described above.

If instead the determined gap is relatively large and/or the relative velocity of the approaching vehicle 5 is low, it may be possible to enter the roundabout 4 ahead of the approaching vehicle 5, if the motor vehicle 1 can be quickly accelerated. A needed acceleration value or range is set as a target acceleration. The target gear is thereafter selected based on the target acceleration and other relevant factors relating to vehicle dynamics of the motor vehicle 1. As the driver depresses the accelerator pedal to enter the roundabout 4, the target gear is engaged in the gearbox in the step 104 and the motor vehicle 1 is accelerated.

In more complex situations, e.g. if several motor vehicles are present in or are approaching the roundabout 4, the positions of those vehicles and their relative velocities may be taken into account for evaluating whether it is possible to enter the roundabout 4 without coming to a complete stop and for selecting the appropriate target gear.

One skilled in the art will appreciate that a method according to embodiments of the present invention may be implemented in a computer program comprising instructions which, when executed in a computer, cause the computer to carry out the method. The computer program usually takes the form of a computer program product which comprises a suitable computer-readable digital storage medium on which the computer program is stored. Said computer-readable digital storage medium comprises a suitable memory, e.g. ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable PROM), flash memory, EEPROM (electrically erasable PROM), a hard disc unit, etc.

An apparatus 2 according to the invention, adapted to carry out the above described steps of the method according to the invention, may comprise one electronic control unit or two or more cooperating electronic control units configured to control different parts of the motor vehicle 1. Fig. 3 illustrates very schematically such an electronic control unit 30 forming part of an apparatus according to an embodiment of the invention. The control unit 30 comprises an execution means 31, such as a central processor unit (CPU), for executing a computer program. The execution means 31 communicates with a memory 32, for example of the type RAM, through a data bus 33. The control unit 30 comprises also a non-transitory data storing medium 34, for example in the form of a Flash memory or a memory of the type ROM, PROM, EPROM or EEPROM. The execution means 31 communicates with the data storing medium 34 through the data bus 33. A computer program comprising computer program code for implementing a method according to an embodiment of the invention is stored on the data storing medium 34.

A motor vehicle 1 according to the invention comprises the proposed apparatus 2. The motor vehicle 1 may preferably, but not necessarily, be a heavy goods vehicle, such as a truck or a bus.

The invention is of course not in any way restricted to the embodiments described above, but many possibilities to modifications thereof would be apparent to a person with skill in the art without departing from the scope of the invention as defined in the appended claims.

Claims

1. A method for automatically selecting a gear in a powertrain of a motor vehicle (1), comprising: - determining (101) that the motor vehicle (1) approaches an intersection, - acquiring (102) information relating to traffic conditions in the intersection, wherein the information includes information about a presence of at least one relevant object in a vicinity of the intersection, wherein the information relating to traffic conditions includes at least one of a position, a speed and a direction of motion of the at least one relevant object, and - based on the acquired information relating to the traffic conditions, selecting (103) a target gear, which target gear is to be engaged when accelerating the motor vehicle (1) in connection with the intersection.

2. The method according to claim 1, wherein acquiring information relating to traffic conditions in the intersection comprises sensing of traffic conditions using at least one sensor provided in or on the motor vehicle (1).

3. The method according to claim 2, wherein the sensing of traffic conditions comprises detecting at least one relevant object in a vicinity of the intersection, sensing a gap to the at least one relevant object from the motor vehicle, and sensing a relative velocity of the at least one relevant object with respect to the motor vehicle (1).

4. The method according to any one of the preceding claims, wherein selecting the target gear comprises: - determining a target acceleration for the motor vehicle (1) in connection with the intersection based on at least the acquired information relating to traffic conditions, and - selecting the target gear based on the determined target acceleration.

5. The method according to claim 4, in which the target acceleration is further determined based on at least a current performance mode of the motor vehicle (1).

6. The method according to any one of the preceding claims, wherein selecting the target gear further comprises: - based on at least the acquired information relating to traffic conditions, evaluating whether it will be possible to enter the intersection without stopping the motor vehicle (1), wherein the target gear is selected based on the evaluation.

7. The method according to any one of the preceding claims, further comprising: - engaging (104) the selected target gear before entering the intersection.

8. The method according to any one of the preceding claims, wherein the powertrain is disengaged during the selection of the target gear.

9. The method according to any one of the preceding claims, wherein determining that the motor vehicle (1) approaches an intersection comprises using data provided from at least one sensor provided in or on the motor vehicle (1).

10. The method according to any one of the preceding claims, wherein determining that the motor vehicle (1) approaches an intersection comprises using positioning information and map data.

11. A computer program comprising instructions which, when the computer program is executed by a computer, cause the computer to carry out the method according to any one of the preceding claims.

12. A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to any one of claims 1-10.

13. An apparatus (2) for automatically selecting a gear in a powertrain of a motor vehicle (1), the apparatus being configured to: - determine that the motor vehicle (1) approaches an intersection, - acquire information relating to traffic conditions in the intersection, wherein the information includes information about a presence of at least one relevant object in a vicinity of the intersection, wherein the information relating to traffic conditions includes at least one of a position, a speed and a direction of motion of the at least one relevant object, and - based on the acquired information relating to the traffic conditions, select a target gear, which target gear is to be engaged when accelerating the motor vehicle (1) in connection with the intersection.

14. A motor vehicle (1) comprising an apparatus (2) according to claim 13.