DE102012024989A1 - Method for determining target-curve inclination of motor vehicle i.e. motor car, while driving motor vehicle on curvilinear lane section, involves calculating modified instantaneous target curve slope by weighting calculated curve slope - Google Patents

Abstract

The method (1) involves determining an instantaneous lateral acceleration (ay) of a motor vehicle based on an instantaneous current speed (vx) of the motor vehicle from sensor data to be provided from a non-optical sensor (2). An instantaneous target curve slope (w-ay) for the motor vehicle is calculated from the determination result of the instantaneous lateral acceleration. A modified instantaneous target curve slope is calculated by weighting the calculated the target curve slope with a velocity-dependent target curve slopes weighting factor. Independent claims are also included for the following: (1) a device for determining a debit curve inclination of a motor vehicle while driving on a curvilinear lane section (2) a motor vehicle.

Description

The present invention relates to a method for determining a desired curve inclination of a motor vehicle when driving on a curved road section and to an apparatus for determining a curve inclination of a motor vehicle when driving on a curved road section. The invention further relates to a motor vehicle with such a device.

The term "Active Body Control (ABC)" electro-hydraulically active suspension systems are known which allow in addition to a conventional suspension and damping function and the possibility of targeted adjustment of pitch and roll angles. As a roll is called thereby a rotary motion of a motor vehicle about its longitudinal axis. Such a rolling motion can result when driving through a curved roadway section through the motor vehicle when the motor vehicle tilts outward due to the centrifugal forces occurring at a certain roll angle. The thereby adjusting roll angle depends on a lateral acceleration of the motor vehicle, its center of gravity, the chassis structure of the motor vehicle and its speed.

The centrifugal forces occurring when driving on the curved road section are often perceived by occupants of the motor vehicle as unpleasant and can therefore lead to a significant reduction in ride comfort. One way to reduce the comfort-reducing effect of such undesirable lateral forces on the occupants of the motor vehicle, is to realize in the motor vehicle by means of "Active Body Control (ABC)" a tilting technology, as they have been used for some time in rail vehicles comes. By using such a tilting technique, it is possible that the force or rail vehicle when driving a curved roadway or rail section not centrifugally due to the outside, but by appropriate control of a chassis of the motor vehicle in the opposite direction, ie inward tilts. For this purpose, the chassis with suitable actuators, for example in the manner of height-adjustable struts, be provided, which connect the vehicle frame height adjustable each with the wheels of the motor vehicle, so that a certain roll angle of the motor vehicle can be adjusted.

Since the centrifugal forces occurring when driving on the curved roadway section of various factors such. B. a roadway curvature of the roadway section or the instantaneous speed, also in the sense of a tilting technology to be set on the chassis of the motor vehicle roll angle must be determined in dependence on these parameters to ensure the highest possible driving comfort in the occupants of the motor vehicle.

The DE 10 2010 046 317 A1 describes a method for adjusting the spatial position of a roll axis about which the motor vehicle is rotatable about a predetermined roll angle. According to the method, initially a spatial desired position of the position of the roll axis is determined in a first step, and subsequently a lateral acceleration of the motor vehicle is determined in a second step. Finally, in a third step, a nominal bank of the motor vehicle and a desired transverse deposit of the motor vehicle are determined as a function of the lateral acceleration so that a displacement of the roll axis is effected in the desired position when setting the desired bank and the desired transverse deposit. To ensure that the motor vehicle assumes the predetermined bank determined in the preceding step, at least one actuator of an active chassis device of the motor vehicle is adjusted accordingly. In addition, at least one actuator for influencing the transverse movement of the motor vehicle is adjusted in such a way that the motor vehicle additionally assumes the desired transverse deposit determined in the preceding step. The expected lateral acceleration can be determined, for example, with the aid of a camera system mounted on the motor vehicle, which optically detects the curved road section to be traveled in advance of the motor vehicle and analyzes it to determine the expected lateral acceleration.

The DE 10 2006 018 978 A1 describes a method for determining the roll angle of a motor vehicle with at least one device for determining the yaw rate or a variable correlated therewith and a device for determining the vehicle speed and an optionally forward-looking camera system. The roll angle is determined using the yaw rate or a magnitude correlated therewith and the specific roll stiffness of the vehicle.

It is an object of the present invention to provide an improved embodiment of a method for determining a desired curve inclination (= roll angle) of a motor vehicle when driving on a curved road section and a device for determining this desired curve inclination.

The above object is solved by the subject matter of the independent claims. Preferred embodiments are subject of the dependent claims.

The invention is based on the general idea of calculating the target curve slope to be determined based on a lateral acceleration determined by means of non-optical sensor technology, wherein a value determined in this way for the setpoint curve slope to be set is weighted as a function of a current speed of the motor vehicle becomes. In this way, by means of the method according to the invention an optimum for the driving of the curved lane section target curve slope (= roll angle) can be determined, which, if adjusted by means of the adjustable chassis of the motor vehicle, leads to a greatly improved ride comfort in the occupants of the motor vehicle , In particular, by means of the weighting of the current setpoint gradient with a speed-dependent weighting factor, an optimized, to be set in the chassis roll angle of the motor vehicle for driving on the curved lane section are determined in which acting on a vehicle occupant lateral forces can be particularly well mitigated or even almost completely suppressed so that the ride comfort for the occupants of the motor vehicle can be significantly increased.

In the method according to the invention, in a first step a) an instantaneous lateral acceleration of the motor vehicle is calculated as a function of a current speed of the motor vehicle from sensor output data provided by a non-optical sensor system. In a second step b), an instantaneous nominal curve gradient for the motor vehicle is then determined from the instantaneous lateral acceleration calculated in step a). Finally, in step c) of the method according to the invention, a modified instantaneous nominal curve gradient is calculated by weighting the desired curve gradient calculated in step b) with a speed-dependent desired curve slope weighting factor. Based on the modified nominal curve inclination calculated in step c), a chassis of the motor vehicle can be controlled with regard to the desired roll angle to be set such that the motor vehicle assumes the roll angle defined by the modified nominal curve angle relative to the road surface of the curved road section to be traveled. For this purpose, the suspension device may be provided, for example with suitable height-adjustable actuators in the manner of spring struts.

In a preferred embodiment, the non-optical sensor system may comprise an acceleration sensor, in particular a g-sensor, which as sensor output data provides a current sensor lateral acceleration value. The sensor output data can be filtered by means of a suitable low-pass filter in order to filter out unwanted high-frequency interference in the sensor output data provided by the acceleration sensor, for example due to unevenness in the road surface traveled by the motor vehicle or the like. Advantageously, such an acceleration sensor is arranged in the motor vehicle with respect to a vehicle longitudinal direction of the motor vehicle as far as possible on the front of the motor vehicle, since in this way curved lane sections can be detected particularly early.

In a further embodiment, it may be contemplated that the instantaneous lateral acceleration is calculated by modifying the current sensor lateral acceleration value taking into account an angle between a vertical direction of the motor vehicle and a gravitational acceleration vector. In this way, the sensor output data provided by the acceleration sensor can be optimized such that g components are taken into account by the acceleration sensor on the basis of an existing roll angle inclination of the motor vehicle relative to the road surface.

Alternatively or additionally, in a particularly preferred embodiment, the non-optical sensor system may comprise a yaw rate sensor which provides a current yaw rate as sensor output data. The present in the form of a current yaw rate sensor output data can optionally be additionally filtered by means of a phase filter and / or a low-pass filter to correct unwanted disturbances in the sensor output data, for example, due to bumps in the road surface of the road to be driven or the like ,

In a likewise preferred embodiment, the non-optical sensor system may comprise a steering wheel angle sensor and / or a wheel angle sensor, which provides a current steering wheel angle or wheel angle of the steering wheel or wheels of the motor vehicle as sensor output data. When determining the instantaneous lateral acceleration from the steering wheel angle or wheel angle, for example, a so-called single-track model can be used for the mathematical calculation. In further-forming, more precise calculation results allowing models, the steering behavior and / or the tire running-in behavior of the motor vehicle can be involved, so that the requirements of a driver of the motor vehicle in the roll angle adjustment can be implemented particularly quickly and effectively in such a holistic view.

By means of the use of different sensor types (acceleration sensor, yaw rate sensor, steering wheel angle sensor, wheel angle sensor) for determining the instantaneous lateral acceleration, the desired curve slope to be calculated independently of an actual lane information can be determined effectively. In particular, while geometric properties of the road surface such. B. roadway elevations o. Ä. Be taken into account in the method according to the invention.

The invention also relates to a device for determining a desired curve inclination of a motor vehicle when driving on a curved road section. The device comprises a control device and a non-optical sensor system which is in communication connection with the control device for transmitting sensor output data. Furthermore, the device comprises a speed sensor which is in communication connection with the control unit for transmitting a current speed of the motor vehicle. According to the invention, the control unit calculates a current setpoint curve gradient for the motor vehicle as a function of the instantaneous speed measured by the speed sensor from the sensor output data of the non-optical sensor system, from which a modified setpoint curve gradient is calculated by weighting with a desired curve weighting factor ,

The non-optical sensor system preferably comprises an acceleration sensor and / or a yaw rate sensor and / or a steering angle sensor and / or a wheel angle sensor for determining the instantaneous lateral acceleration.

The invention further relates to a motor vehicle having a device with the features mentioned above, as well as to a suspension device which can be activated by the control device of this device, by means of which the modified nominal curve inclination determined by the control device can be adjusted on the motor vehicle.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

In each case show schematically:

1 a rough schematic flow chart of the method according to the invention,

2 a motor vehicle with a device according to the invention for adjusting the inclination of a motor vehicle, wherein the 2a a plan view and the 2 B a rear view of the motor vehicle shows.

In the 1 a flow chart of the method according to the invention is shown roughly schematically and with 1 designated. In a first step S1, an instantaneous lateral acceleration a _{y of} the motor vehicle as a function of a current speed v _{x of} the motor vehicle is determined by a non-optical sensor system 2 provided sensor output data. To determine the instantaneous lateral acceleration a _y , the non-optical sensor 2 an acceleration sensor 3 comprising as sensor output data provides a current sensor lateral acceleration value a _y ^sensor . By using various indices y and x, it is to be expressed that a direction vector of the current lateral acceleration a _y (in the Y direction) points in a direction orthogonal to the corresponding direction vector of the current speed v _{x of} the motor vehicle (in the X direction) (see. 2a ). The sensor output data can be determined by means of a suitable low-pass filter 4 are filtered to avoid unwanted high-frequency interference (for example, due to bumps in the roadway section just traveled) in the acceleration sensor 3 to filter out provided sensor output data. Advantageously, such an acceleration sensor 3 in the motor vehicle with respect to a vehicle longitudinal direction of the motor vehicle as far as possible arranged on the front of the motor vehicle (see. 2a ).

The calculation of the instantaneous lateral acceleration a _y may include modifying the current sensor lateral acceleration value a _y ^sensor such that an angle φ between a vertical axis Z and a g vector (direction vector of the acceleration due to gravity) is taken into account in the calculation (cf. 2 B ). For the accelerometer 3 measured instantaneous transverse sensor acceleration value a _y ^sensor and the instantaneous lateral acceleration a _y to be determined and the instantaneous relative angle φ between the vertical axis Z of the motor vehicle and a Direction of the gravitational acceleration vector g is the relationship a _y = a _y ^sensor + g sin φ, where g is the acceleration of gravity and φ the angle between the vertical vehicle direction Z and the earth's surface (= plane orthogonal to the acceleration vector g). In this manner g portions can be taken into account in the sensor output data _y a ^sensor in the calculation of the current sensor lateral acceleration value a _y.

Alternatively or in addition to the acceleration sensor 3 can the non-optical sensors 2 also a yaw rate sensor 5 which provides, as sensor output data, a current yaw rate d / dt ψ, where ψ is the instantaneous yaw angle. The calculation of the instantaneous lateral acceleration a _y from the instantaneous yaw rate is effected in accordance with the equation a _y = (d / dtψ) v _x , where a _{y is} the instantaneous lateral acceleration, d / dt ψ is the instantaneous yaw rate, and v _{x is} the instantaneous speed of the yaw Motor vehicle is. This means that a knowledge of the instantaneous vehicle speed v _{x of} the motor vehicle is also required to determine the instantaneous lateral acceleration a _y from the yaw rate d / dt ψ. The instantaneous speed v _{x of} the motor vehicle may be used in the method according to the invention, for example by means of a conventional speed sensor installed in the motor vehicle 6 be determined.

Alternatively or in addition to the previously explained sensors (acceleration sensor 3 and yaw rate sensor 5 ) may be the non-optical sensor 2 also a steering wheel angle sensor and / or a wheel angle sensor 7 which as sensor output data then provides a current steering wheel angle or current wheel angle δ. From the steering wheel angle sensor or wheel angle sensor 7 In this case, the instantaneous lateral acceleration a _y can be calculated using the so-called one-track model by means of the relationship a _y = v _× ² δ / (I + EG v _× ² ). In this case, δ is the steering wheel angle or wheel angle, I is the wheelbase of the motor vehicle and EG is the so-called self-steering gradient of the motor vehicle. Of course, instead of the one-track model, even more complex relationships which take into account a steering model and / or a tire run-in behavior of the motor vehicle can be used to calculate the instantaneous lateral acceleration a _y from the steering wheel angle or wheel angle δ. The instantaneous speed v _{x of} the motor vehicle can in turn be detected by means of the speed sensor installed in the motor vehicle 6 be determined.

In a second step S2 of the method according to the invention, an instantaneous setpoint gradient w ( _ay ) is determined as a function of the instantaneous lateral acceleration a _{y of} the motor vehicle from the previously determined instantaneous acceleration a _y (v _x ). Such a functional dependency of the instantaneous nominal curve slope w (a _y ) on the speed v _x can be in the manner of a characteristic diagram 8th be set. Alternatively, however, it is also possible to define an analytical relationship between the instantaneous nominal curve gradient w (a _y ) and the instantaneous velocity v _x .

In a third step S3 of the inventive method from the calculated in step S2, the current target bank angle w (a _y) by means of weighting with a speed-dependent weighting factor G (v _x) a modified current target curve inclination w _G (a _y, v _x) be calculated. For this purpose, the setpoint gradient weighting factor G (v _x ) is multiplied by the previously determined momentary setpoint gradient w (a _y ). The speed-dependent weighting factor G (v _x ) can be determined by a predetermined functional dependence of the weighting factor G on the speed v _{x of} the motor vehicle. Such a functional dependency can, for example, be in the form of a characteristic diagram 9 be defined; Alternatively, however, an analytical relationship between the speed-dependent weighting factor G (v _x ) and the speed v _x can also be defined.

It is clear that the method according to the invention iteratively performed iteratively in practice in a motor vehicle, so that when driving a curved road section of the calculated by means of the method roll angle are constantly updated and thus changing road conditions or changes in the current speed of Motor vehicle can be adjusted.

The method according to the invention may further comprise an optional (in the 1 indicated by dashed lines) comprise step S2 ', according to which it is determined whether a predetermined external condition B is satisfied, and, if so, the current target curve slope w (a _y ) determined in step S2 to a predetermined maximum value w _max is reduced if the current desired curve slope w (a _y ) exceeds the predetermined maximum value w _max . Such an external condition B may, for example, be the actuation of a turn signal by a driver of the motor vehicle if he intends to change the lane when driving on the curved lane section. By temporarily reducing the current setpoint slope w (a _y ) to such a maximum value w _max , the curve inclination of the motor vehicle can then additionally be reduced in order to change the occupants of the motor vehicle To make the lane as comfortable as possible. After completion of such a lane change then such a temporary reduction of the current setpoint slope w (a _y ) can be canceled again to a predetermined maximum value. Of course, come as a predetermined external conditions B instead of the above-explained operation of the turn signal also other events into consideration. For example, in one variant, it may be thought that an optical detection system detects an intended lane change. In this case, the predetermined external condition B, which must be satisfied, would not be the operation of a turn signal, but quite generally an intended lane change of the motor vehicle detected by a suitable detection system.

In the presentation of the 2 is a motor vehicle 10 with a device according to the invention 11 for determining a desired curve gradient when driving on a curved road section 20 shown. The 2a shows the motor vehicle 10 in a plan view, the 2 B in a rear view. The device 11 includes a controller 12 as well as the acceleration sensor 3 , a yaw rate sensor 5 , and a steering angle / wheel angle sensor 7 , each with the control unit 12 in communication.

To carry out the method according to the invention, the acceleration sensor transmits the instantaneous transverse sensor acceleration a _y ^sensor , the steering angle / wheel angle sensor 7 the current steering wheel angle or current wheel angle δ, and the yaw rate sensor 5 the instantaneous yaw rate d / dt ψ to the controller 12 , In simplified variants may refer to one or two of the aforementioned three sensors 3 . 5 . 7 be dispensed with. The control unit 12 can be a control unit 13 (ECU) and one with the control unit 13 communicatively connected storage unit 14 include. The control unit 13 and the storage unit 14 may be formed in the manner of a conventional micro-controller, the skilled person numerous technical implementation options are known.

The control unit 12 synonymous with the speed sensor 6 in communication connection, which is the instantaneous speed v _{x of} the motor vehicle 10 to the control unit 12 transmitted. In the control unit 12 is carried out using the above-mentioned input parameters (instantaneous speed of the motor vehicle v _x , yaw rate d / dt ψ and / and current steering wheel angle or momentary wheel angle δ or / and instantaneous sensor lateral acceleration a _y ^sensor ) the inventive method. The maps 8th and 9 can do it in the storage unit 14 be stored and by the control unit 12 for the execution of the method steps S2 and S3 are read out. In the event that the storage unit 14 is a writable memory, the maps can be 8th and 9 by overwriting the corresponding memory area in the memory unit 14 modify, for example, if individual maps are to be used for different types of motor vehicles. From the controller 12 in step S1 of the method according to the invention, the instantaneous lateral acceleration a _y (v _x ) of the motor vehicle 10 calculated. From the instantaneous lateral acceleration a _y (v _x ), the modified instantaneous nominal curve gradient w _G (a _y , v _x ) is calculated in accordance with the steps S2 and S3.

The car 10 includes one of the controller 12 controllable suspension device 15 , which may be formed in the manner of an electro-hydraulically active chassis. The landing gear device 15 comprises four actuators designed as height-adjustable struts 16 , with each wheel 17 of the motor vehicle an actuator 16 assigned. By individually adjusting the actuating height of the actuators 16 can be determined by means of the method according to the invention predetermined curve slope w _G (a _y , v _x ) (ie the desired roll angle) on the motor vehicle 10 be set.

Alternatively to the above-described electro-hydraulic suspension device 15 It is also possible to use a pneumatic spring-based chassis with a closed pressure supply. In such a spring-based suspension to adjust the struts, the air is pumped in a closed circuit of an air reservoir in the air spring and vice versa, which allows a very fast retraction and extension of the struts to set the desired curve slope in the chassis of the motor vehicle.

In a further alternative to the electro-hydraulically active chassis, a hydraulically adjustable undercarriage known as "ACTIVE CURVE SYSTEM" can be used, which operates with a belt-driven hydraulic pump and an oil tank in the engine compartment as well as a valve block and active stabilizers Has front and rear axle. Such a hydraulic suspension device can also be used to set the desired curve inclination in the motor vehicle.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102010046317 A1 [0005]
• DE 102006018978 A1 [0006]

Claims (8)

Procedure ( 1 ) for determining a setpoint gradient (w _G (v _x )) of a motor vehicle ( 10 ) when driving on a curved roadway section ( 20 ), comprising the following steps: a) determining a momentary lateral acceleration (a _y ) of the motor vehicle ( 10 ) in dependence on a current speed (v _x ) of the motor vehicle ( 10 ) from a non-optical sensor ( 2 b) calculating a current setpoint gradient w (a _y ) for the motor vehicle ( 10 ) (From the time determined in step a), the current transverse acceleration a _y), c) computing a modified current target curve inclination w _G (v _x) w by weighting the calculated in step b) target curve slope (a _y) with a speed-dependent target Curve slope weighting factor (G). Procedure ( 1 ) according to claim 1, characterized in that the non-optical sensors ( 2 ) an acceleration sensor ( 3 ), in particular a g-sensor, which as the sensor output data provides a current sensor lateral acceleration value (a _y ^sensor ). Procedure ( 1 ) according to claim 2, characterized in that the calculation of the instantaneous lateral acceleration (a _y ) by modifying the instantaneous sensor lateral acceleration value (a _y ^sensor ) taking into account an angle (φ) between a vertical direction (Z →) of the motor vehicle ( 10 ) and a gravitational acceleration vector (g →). Procedure ( 1 ) according to one of claims 1 to 3, characterized in that the non-optical sensors ( 2 ) a yaw rate sensor ( 5 ) which provides a current yaw rate (d / dt ψ) as sensor output data. Procedure ( 1 ) according to one of the preceding claims, characterized in that the non-optical sensors ( 2 ) a steering wheel angle sensor and / or a wheel angle sensor ( 7 ), which provides an instantaneous steering wheel angle or current wheel angle (δ) as sensor output data. Contraption ( 11 ) for setting a curve inclination (w _G (a _y , v _x )) of a motor vehicle ( 10 ) when driving on a curved roadway section ( 20 ), - with a control unit ( 12 ), - with one with the control unit ( 12 ) for the transmission of sensor output data in communication-connected non-optical sensor technology ( 2 ), - with one with the control unit ( 12 ) for transmitting a current speed (v _x ) of the motor vehicle ( 10 ) in communication connection speed sensor ( 6 ), - whereby the control unit ( 12 ) as a function of the instantaneous speed (v _x ) from the sensor output data of the non-optical sensor system ( 2 ) a momentary desired curve inclination (w (v _x )) for the motor vehicle ( 10 ) and calculate therefrom by weighting with a desired slope weighting factor (G (v _x )) a modified setpoint slope (w _G (v _x )). Contraption ( 11 ) according to claim 6, characterized in that the non-optical sensors ( 2 ) an acceleration sensor ( 3 ) and / or a yaw rate sensor ( 5 ) and / or a steering angle sensor ( 7 ) and / or a wheel angle sensor ( 7 ) for determining the instantaneous lateral acceleration (a _y ). Motor vehicle ( 10 ), - with a device ( 11 ) according to claim 6 or 7, - with one of the control unit ( 12 ) controllable landing gear device ( 15 ), by means of which by the control unit ( 12 ) certain modified setpoint slope w _G (v _x ) on the motor vehicle ( 10 ) is adjustable.

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