GB2569284A - Method and computer program for drift assist in a motor vehicle - Google Patents

Abstract

The invention refers a method for drift assist in a motor vehicle, applicable in assessing driver’s skills, in particular when it concerns driving sportive car in a motorsport competition. The drift assist method, involves using drift-related data e.g. drift angle or yaw rate, derived from an airbag sensor (Fig.3, 1) of an ego-vehicle and associating the data with location data assigned to a mapped region. The drift-related data are graphically displayed on a map 13 covering the retrieved location as a continuous trace 14 of the ego-vehicle as a movable object E in the direction of travel. The drift data may be displayed in real time. The display may show a trace of the displacement and orientation of the vehicle in different directions. The data may be displayed as a combined graphical representation of pitch angle and altitude information.

Description

Method and computer program for drift assist in a motor vehicle The invention relates to a method for drift assist in a motor vehicle. It further relates to a computer program for carrying out such a method. The method and the associated computer program are applicable in assessing driver's skills, in particular when it concerns driving sportive car in a motorsport competition.

Vehicle dynamics variables, in particular information such as yaw rate, steering angle and/or lateral and longitudinal acceleration of a vehicle are very important, since these data can be used for vehicle dynamics control. It is known the so-called integrated sensor cluster, which place a yaw rate sensor and a lateral acceleration sensor in a common housing, as well as a computing unit, as it is disclosed by WO 2008 003 346 Al. In order to reduce redundancy, DE 101 079 49 B4 proposes to combine the sensor cluster with the airbag control device. Moreover, according to the invention disclosed by EP 2681 086 Bl, an intelligent vehicle sensor device integrates a steering angle sensor with other sensors in a housing, and a computing unit carries out plausibility checking and/or calibration of the yaw rate signals and/or the lateral acceleration signals and/or the steering angle signals.

On the another side, it is also of interest to indicate such dynamics variable data correlated with position or altitude, hence by combining localization data provided via Global Positioning System (GPS), alone or in combination with global satellite navigation data from other satellite navigation systems, such as Galileo or GLONASS, if available. Anyway, the GPS information alone can tell where the vehicle is (position and altitude) , but not what direction it is facing. In this respect, there is described an invention combining acceleration information with localization information, and indicating them in a graphical form, as it is disclosed by DE 10 2009 041 194 Al.

Anyway, none of the afore-mentioned inventions have addressed the visual impact of displaying the vehicle trace derived exclusively from the yaw rate information.

Therefore, the technical problem to be solved is to bring the real-time yaw rate information present at an airbag control unit from a non-friendly user mode (watchdog) into the world of images (infotainment).

The object of the invention is to indicate means to graphically present driving performance data, in particular drift angle and/or yaw rate, and place those data in a meaningful context.

According to the invention, this obj ect is achieved by the subj ect matters of the independent claims, namely a method for drift assist in a motor vehicle and a computer program for carrying out such a method.

With regard to the method, the aforementioned object is achieved according to the invention by deriving drift angle value from yaw rate information and correlate it with position as to construct a trace. The drift angle corresponding to a certain position at a certain time is advantageously shown to the driver via a graphical display.

The main advantage of the invention is, in particular, that by using a map in assisting the driver during the drift mode, the driver awareness about its sportive driving skills is increased. The use of a map allows correlation of particular dynamics variables such as drift angles and yaw rates along a vehicle trace .

Another particular advantage is that the drift assist method uses information already available on-board.

With regard to the drift assist computer program, the aforementioned object is achieved by software instructions whereby the method according to the invention is implemented.

Further advantageous developments are the subject matter of the dependent claims.

In a preferred embodiment of the method, the drift angle information can be visualized by a trace of a displayed movable object, wherein in particular can be displayed by a displacement and orientation of the movable object in different directions. Such graphic processing further simplifies the information acquisition for the driver.

In this manner, the driver could make a qualitative assessment of the drift-related information.

In an advantageous embodiment, the movable object may be formed as a top seen vehicle. Advantageously, the dynamics variables such as drift angle, yaw rate, speed, accelerations and similar data can be displayed in alphanumeric form, next to the map, as to allow the driver to make a quantitative assessment of the driving performance.

In a particularly complex embodiment, the graphical display can be designed such that a combined graphical representation of pitch angle and altitude information is possible.

For a complete understanding of the invention and the advantages thereof, exemplary embodiments of the invention are explained in more detail in the following description with reference to the attached figures, in which similar reference numbers designate similar parts. In the figures:

- Fig. 1 shows the dynamics variables of a vehicle, namely the angles of rotation in three dimensions about a body's center of gravity, known as pitch, roll and yaw;

- Fig. 2a illustrates what no yaw means for a vehicle;

- Fig. 2b shows a drift angle for a yawed vehicle;

- Fig. 3 shows a preferred embodiment of the arrangement according to the invention,

- Fig. 4 shows an embodiment of a preferred embodiment of displaying dynamics variables of interest for drift assist method, according to the invention.

As it is shown in Fig. 1, vehicle dynamics can be expressed by six kinematic variables, namely the forward motion along the X axis, the lateral motion along the Y axis, the vertical motion along the Z axis, as well as the three angles of rotation expressing the orientation, namely the rotation about the X axis

- roll, about the Y axis - pitch, or about the Z axis - yaw. In Fig. 1, the reference number 1 is related to a sensor, for example a yaw rate sensor integrating also an accelerometer.

Particular information such as yaw becomes extremely important in atypical situations, namely for a motorsport vehicle taking a turn in a drift mode, when the driver intentionally oversteers while maintaining control and driving the car through a curve. Drift mode means that there is a difference between the heading angle over the ground of the vehicle and the heading angle (orientation of the vehicle's longitudinal axis), the so-called drift angle. Usually drift angles above 5° mean that there is a drifting process. Fact is that air hits the car differently when the car is at an angle to the oncoming air, compared to when it is hitting the air head on. As a consequence, a car yawed before it enters the turn is helped by the oncoming air to gain seconds ahead on the turn. However, from the steering angle alone, no information about the drift angle desired by the driver can be derived.

Fig. 2a illustrates the situation of a vehicle not yawed, by comparison to the Fig. 2b which shows a vehicle yawed with a drift angle d.

For a desired drift, the yaw rate ψ of the vehicle corresponds to the yaw rate required at the vehicle speed v for a curve with a radius R: ψ = v/R. By measuring the yaw rate ψ and the speed v, it is possible to derive the radius R of the turn taken by the vehicle .

Fig. 3 shows an integrated drift-assist arrangement A which uses inertial variables such as yaw rate from at least one airbag sensor 1 connected via an interface 2 (for example, a Peripheral Sensor Interface PSI5) to a control unit 3 (for example, an Airbag Control Unit, ACU). Control unit 3 contains a processor (not illustrated) programmed to process the received data in order to calculate at least the drift angle values, and to send them to a display instrument 4 (for example, an instrument cluster integrating several interfaces for data exchange) provided with a data logger 5. A USB port 41 is used to access mobile storage media. On the other side, the processed data can be sent via a data bus 6 (which can be a high-speed data bus, as Central Area Network (CAN) or FlexRay, or a low-speed bus) to a gateway 7 (wirelessly designed or for connecting a USB storage media with route data via which a map including the course of the road data can be read), and further on to a localization system 8 (based, for example, on GPS signal), from which the processed data are further sent via an infotainment bus 9 to a graphical display unit 10, and/or to external means 11 (such as a mobile device) used as transmitting and receiving devices for WLAN, Bluetooth, GSM and UMTS. It is also possible to send drift-related data over the Internet to a server or retrieve it from a server.

The airbag sensors 1 are preferred as part in this arrangement, since when they are integrated into the electronic stability system (ESC), for example, they not only measure the yaw rate, but also pitch rate and/or roll rate (when the vehicle is equipped with side airbags, for example), so the sensors could be MEMS inertial sensors with up to 6 degrees of freedom (DOF) . From the point of view of the present method, another driving performance data to be taken into account or displayed is the pitch rate/pitch angle, mostly correlated with altitude - for example, when the ego vehicle is taking a race on a rough terrain.

Fig. 4 shows a graphical display instrument adapted to indicate the drift-assisting data according to the afore-mentioned method. The localization system 8 is integrated in the graphical display unit 10. In addition, the graphical display unit 10 (for example, a head-up display unit designed as a touchscreen) has its own memory device 12, which is preferably erasable by user. A stored map 13 can be displayed on the display unit 10. In addition, a movable circular object E corresponding to the ego-vehicle is shown on the display, advancing at current or already traveled positions, so that a trace 14 can be build. Finally, the trace 14 and the associated drift-related data and/or other driving performance data are stored in the memory device 12.

The corresponding drift-related data and/or other driving performance data may be displayed in another display area 15 next to the map 13. Optionally, only locations of maximum drift angle can be displayed for each curve on the road. Thereby, the selection of the displayed drift-related data can be optimized so that all important data are shown without the map becoming confusing .

The drift-assist method according to the invention is performed as follows : once a drift mode is initiated by the driver, allowing the vehicle to perform a controlled drift with no interference from systems such as Electronic Stability System (ESC) (which means the ESC is switched off), the initial direction of travel is matched up with map data by means of software. Drift-related data derived from an airbag sensor of the ego-vehicle E are associated with location data assigned to a mapped region, and drift-related data are graphically displayed on a map covering the retrieved location as a continuous trace of the ego-vehicle in the direction of travel. Drift-related data are at least drift angle values, combined or not with other driving performance data, such as speed, lateral and/or longitudinal acceleration, radius of the turn taken by the ego-vehicle etc.

Drift angle information are designed to be visualized as a trace of a movable object E corresponding to the ego vehicle, in particular a trace of displacement and orientation of the movable object in different directions.

In one preferred embodiment, the movable object may be formed as a top seen vehicle.

Drift-related data could be displayed in real-time, or delayed, wherein a delay can be set by the user or dependent on a driving condition and/or location. Further on, displayed drift-related information are determined within time intervals and displayed after the end of the time interval, for example the time interval tl-t5, delimited by tl and t5 markers on the embodiment illustrated by Fig. 4.

Moreover, drift-related data can be stored, so that they can be retrieved later on.

Also, when the airbag sensor is integrated within an intelligent sensor cluster, where dynamics information are completed with steering angle values, for example, the ego-vehicle E is designed to be graphically displayed as a movable obj ect where the steering angle is visible changed according to the respective values.

In a more complex embodiment, when the ego-vehicle E is equipped with airbag sensors having inertial sensors able to measure not only the yaw rate, but also pitch rate and roll rate, such driving performance information are processed and graphically displayed in a more complex combination, namely drift angle values correlated with position and pitch angle values correlated with altitude .

While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.

LIST OF REFERENCE SIGNS

A Drift Assist Arrangement

E Movable Object

Sensor

Interface

Airbag Control Unit

Instrument Cluster

Data Logger

Data bus

Gateway

Navigation System

Infotainment Bus

Display Unit

Mobile Device

Memory Device

Map

Trace

Display area

Claims (10)

Patent claims

1. Method for drift assist in a motor vehicle, characterized by that drift-related data derived from an airbag sensor (1) are associated with location data assigned to a mapped region, and drift-related data are graphically displayed on a map (13) covering the retrieved location as a continuous trace of the ego-vehicle in the direction of travel.

2. Method according to claim 1, characterized by that the drift-related data are at least drift angle values.

3. Method according to claims 1-2, characterized by that drift angle information are designed to be visualized as a trace of a movable object (E) corresponding to the ego vehicle, in particular a trace of displacement and orientation of the movable object (E) in different directions.

4. Method according to claims 1-3, characterized by that the movable object may be formed as a top seen vehicle.

5. Method according to claim 1, characterized by that drift-related data are displayed in real-time.

6. Method according to claim 1, characterized by that drift-related data are displayed delayed, wherein a delay can be set by the user or dependent on a driving condition and/or location.

7. Method according to claims 1-6, characterized by that drift related data are stored, so that they can be retrieved later on.

8. Method according to claims 1-7, characterized by that the displayed data are designed as a combined graphical representation of pitch angle and altitude information.

5

9. Method according to claims 1-9, characterized in that displayed drift-related information are determined within time intervals and displayed after the end of the time interval.

10. Computer program product with program code stored on a

10 machine-readable carrier for carrying out the method according to one of claims 1 to 9.