VEHICLE SUBSYSTEM CONTROL METHOD AND APPARATUS

Abstract

A method is provided for controlling at least one setting parameter in at least one active subsystem in a vehicle chassis. The method includes, but is not limited to the steps of identifying the driver and selecting the decision function associated to the identified driver from a set of predetermined decision functions, determining one or more operating parameters of the vehicle, evaluating the decision function which yields a value of the setting parameter corresponding to the determined operating parameters, and setting the value in said subsystem.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National-Stage entry under 35 U.S.C. § 371 based on International Application No. PCT/EP2007/002516, filed Mar. 21, 2007, which was published under PCT Article 21(2) and which claims priority to German Application Nos. 102006013580.0, filed Mar. 22, 2006, 102006013572.0, filed Mar. 22, 2006, and 102006013621.0, filed Mar. 22, 2006, which are all hereby incorporated in their entirety by reference.

TECHNICAL FIELD

The present invention relates to a method for controlling at least one active subsystem in a vehicle chassis and to apparatus for carrying out the method.

BACKGROUND

Conventionally, motor vehicles had a number of chassis subsystems, such as shock absorbers, brakes, suspensions, steering system, powertrain, etc., characteristics of which were determined by manufacture, and it is a tedious task to adapt these to each other so that a harmonic driving feeling, good road holding etc., resulted, so that normally resulted only a more or less satisfying compromise between contradictory requirements could be reached.

In modern vehicles, many of these subsystems are electronically controlled, so that their characteristics can be modified in operation. For example, from EP 1 355 209 A1, a motor vehicle is known in which subsystems, such as an engine controller, a transmission controller, a steering controller, a brake controller and an air suspension controller, can assume different operating states under the control of a master controller. This master controller can receive direct input from a user (e.g., via a switch) which allows the user to specify a type of ground, on which the vehicle is moving, and operating modes such as normal, sport and towing modes. Specifically, there is described in this document in a third embodiment in which a driver may use a first rotating knob for inputting the type of terrain over which the vehicle is being driven, and a second knob for selecting between sport, normal and towing modes (i.e., in this embodiment, the driver may adapt the way the vehicle behaves to his personal taste by selecting between normal and sporty modes). However, in each of these modes, the settings of the subsystems have to be such that each of them fits straight driving, cornering, accelerating, braking etc.; (i.e., the settings still are a compromise which may fit one driving situation better than the other).

In a fourth embodiment described in this document, the master controller uses information from the various subsystems on the manner in which the vehicle is being driven and the way in which it is being used for selecting an appropriate mode automatically, and a powertrain controller and a steering wheel sensor are used to classify the driving style as normal or sporty. By adapting automatically to the driving conditions, the need for compromise is reduced because settings specifically adapted to each driving condition may be used. However, the driver has no possibility of adapting the behavior of the chassis to his personal likings.

In view of the foregoing, at least one object of the present invention is to provide a method for controlling at least one active subsystem in a vehicle chassis, and means for carrying out the method, which make full use of the flexibility such active subsystems can provide. In addition, other objects, desirable features, and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.

SUMMARY

This at least one object, and other objects, desirable features and characteristics, are achieved by a method for controlling at least one setting parameter in at least one active subsystem in a vehicle chassis, comprising the steps of identifying the driver, selecting a decision function associated to the identified driver from a set of predetermined decision functions, determining one or more operating condition parameters of the vehicle, evaluating the selected decision function which yields a value of the setting parameter corresponding to the determined operating parameters, and setting the value in the subsystem.

In principle, the value of each setting parameter might be a continuous function of the operating condition parameters. In that case, it is difficult to demonstrate that all possible combinations of setting parameters are technically reasonable. It is therefore preferred that the decision function should have a moderate number of discrete values. According to a first embodiment, this can be achieved by defining a threshold for at least a first one of the operating condition parameters, the decision function yielding for result a first one of the discrete values if the first operating condition parameter is below the threshold and a second one of the discrete values if the first operating condition parameter is above the threshold, and the threshold is dependent on the identified driver.

According to a second embodiment, discrete values of the decision function are achieved by defining a threshold for at least a first one of the operating condition parameters, the decision function yielding for result a first one of the discrete values if the first operating condition parameter is below the threshold and a second one of the discrete values if the first operating condition parameter is above the threshold, and at least one of the first and second discrete values is dependent on the identified driver.

The decision functions associated to each subsystem preferably have identical thresholds, so that whenever a threshold is passed, several setting parameters change.

Preferably the operating parameters comprise one or more of:

• • vehicle longitudinal speed;
  • vehicle lateral speed;
  • vehicle yaw rate;
  • vehicle pitch rate;
  • steering wheel rotating speed;
  • accelerator pedal position;
  • brake pedal position;
  • time derivatives of any of the above.

The at least one active subsystem may be one of the following:

• • an all-wheel drive controller, at least one setting parameter of which corresponds to an all-wheel drive mode being either on or off,
  • a shock absorber controller, a setting parameter of which corresponds to different degrees of shock damping,
  • a power steering controller, a setting parameter of which corresponds to different degrees of driver assistance provided by the power steering controller,
  • a steering controller, a setting parameter of which corresponds to different relations between steering wheel (1) and front wheel (2) turning angles,
  • a powertrain controller (7), states of which have different gear shifting characteristics,
  • a load controller (6) for controlling motor (5) load according to an accelerator pedal (4) position, setting parameter of which corresponds to different pedal position/load characteristics, a brake controller (10).

Specifically, the state, on or off, of an all-wheel drive controller may be selected automatically depending on vehicle longitudinal speed or acceleration, in which case different drivers may prefer different speed or acceleration thresholds above which the controller automatically switches from all-wheel drive to two-wheel drive mode. The degree of shock damping in a shock absorber controller may be set depending on vehicle longitudinal or lateral speed, yaw rate or pitch rate, tending to select higher rigidity at high speeds or high yaw rate or at a low pitch rate, and the desired degree of damping may be different according to the driver's taste. Different states of the steering controller may also be selected based on vehicle speed or yaw rate, some drivers preferring a generally high level of assistance, while others prefer to feel a direct feedback from the steering gear. Different relations between steering wheel and front wheel turning angles may be set depending on vehicle speed. Here drivers may prefer different thresholds for switching over between two angle ratios, or different ratios between which to switch over at a given threshold, or a driver may prefer to have no switchover at all and a constant ratio at all speeds.

Preferably, the driver is identified based on information input by himself/herself at a user interface or based on biometric recognition.

The set of decision functions is preferably defined based on input from the driver.

A motor vehicle for carrying out embodiments of the present invention comprises a chassis having at least one active subsystem and a controller for controlling at least one setting parameter in the at least one active subsystem, the controller being adapted to determine one or more operating condition parameters of the vehicle, to evaluate a decision function which yields a value of said setting parameter corresponding to the determined operating parameters, and to set the value in said subsystem, means for identifying a driver of the vehicle and means for selecting the decision function associated to the identified driver from a set of predetermined decision functions.

The invention may further be embodied in a computer program product comprising program code means for enabling a computer, when the code is carried out on it, to execute the method as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and

FIG. 1 is a block diagram of a motor vehicle according to an embodiment of the present invention;

FIG. 2 is a flowchart of a control method carried out by the controller of FIG. 1; and

FIG. 3 is a graph which illustrates the effects of editing a decision function.

The schematic diagram of a motor vehicle illustrating in block form some components which are relevant to the present invention. It should be understood that these components are not necessarily essential to the invention, and that the invention may be applicable to other components that those shown, too.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.

A steering wheel 1 controls the steering angle of front wheels 2 of the motor vehicle by means of a power steering controller 3. The power steering controller 3 has actors for turning the front wheels 2 in proportion to the angular position of steering wheel 1, and actors for exercising on the steering wheel 1 a counter-torque to a torque imposed by the driver. The power steering controller 3 supports a plurality of operating states which differ from each other by the degree of assistance provided to the driver(i.e., by the proportion between the torque applied by the actors to the front wheels and the counter-torque experienced by the driver). The power steering controller 3 further has a so-called Active Front Steering functionality (i.e., it supports a number of states having different ratios between the angle by which the driver turns steering wheel 1 and the corresponding yaw angle of the front wheels 2).

An accelerator pedal 4 controls the load of an engine 5 via an electronic engine controller 6. Engine controller 6 supports a plurality of states which use different characteristics for controlling the motor load as a function of the accelerator pedal position and selects one of these based on a setting parameter input to it. There may be, for example, a “calm” state in which the load varies little with the pedal position, and a “dynamic” state in which the load varies strongly with the pedal position.

A transmission controller 7 controls a gearbox 8 based primarily on engine load and speed detected by sensors, not shown, at engine 5. A gearshift lever 9 is connected to the transmission controller 7, so as to enable the driver to choose between different states of the transmission controller 7, which use different algorithms for selecting the gear ratio in gearbox 8 based on engine speed and load, or for overriding a gear ratio selected by transmission controller 7.

The transmission controller 7 may also be adapted to switch over between a two-wheel drive state and a four-wheel drive state, either based on the input from the driver or automatically, based e.g. on driving speed.

Electronic brake controller 10 controls the reaction of brakes, not shown, provided at the vehicle wheels, to the driver pressing a brake pedal 13. The brake controller 10 may implement conventional brake control schemes such as an anti-blocking system or an electronic stability program ESP, and different states of the brake controller 10 may vary in the amount of wheel slippage permitted before the anti-blocking system or the ESP is activated.

A suspension controller, not shown, is provided for controlling the stiffness of the vehicle's wheel suspension, different states of the suspension controller corresponding to different degrees of rigidity it imposes upon shock absorbers of the wheels.

All these controllers 3, 6, 7, 10 are connected as sub-controllers or slave controllers to a master controller 11 by a bus system 12.

The bus system 12 may have a linear structure in which all controllers are connected in parallel to a same bus line and data transmitted on the bus by one of the controllers are received in parallel by all others.

In FIG. 1, the bus system 12 is shown to have an annular structure with bus segments extending from master controller 11 to engine controller 6, from engine controller 6 to transmission controller 7, and so on, and finally, from brake controller 10 back to master controller 11. In such a bus system, the master controller 11 can judge that data sent by it were received correctly by all other controllers, if these data, after making a complete turn on the bus system 12, are received uncorrupted at the master controller 11 again.

The master controller 11 further has a user interface or driver interface 16 connected to it. In the embodiment shown in FIG. 1, the driver interface 16 is connected to the master controller 11 by a dedicated line, but the driver interface 16 might also be installed as a further node, in addition to the controllers 3, 6, 7, 10, 12, along bus system 12.

The user interface 16 may be a conventional input and display device comprising, for example, a display screen for displaying to the user internal status information of the master controller 11 or for prompting him to input data required by the master controller 11, a keyboard, a scroll wheel or similar devices for allowing the driver to input the required information. It may also comprise a microphone for receiving spoken information from the driver, a camera arranged to detect the driver, a card reader or a similar reading device for reading a compact data carrier which the driver can comfortably carry in a pocket or a wallet, etc.

The task of the master controller 11 is to identify the driver when he attempts to start the vehicle engine, and to control the various sub-controllers 3, 6, 7, 10 according to the personal taste of the identified driver. FIG. 2 is a flow chart of an operating method by which the master controller 11 achieves this goal.

When an attempt to start the engine is detected, the master controller 11 identifies the driver in step S1. In the simplest case, identification of the driver is carried out based on information which the latter deliberately inputs at interface 16. To this effect, the user interface may, for example, comprise a knob or a set of keys which enable the driver to identify himself by putting the knob in a position associated to his person or by pressing an associated key or key sequence.

In a more advanced embodiment, driver identification may still rely on information which is deliberately input by the driver, but this information may take a huge number of values, only few of which are indeed associated to a driver. The driver may, for example, be required to input a personal identity code comprising several digits on a keyboard of the interface 16, and only if the input code corresponds to a driver code registered in the master controller 11 is the driver allowed to proceed and to start the engine. In this way, the driver identification of step S1 also provides effective protection against vehicle theft.

According to a still more advanced embodiment, the driver may input his identity code information not by using keys, but by bringing a portable data carrier into communication with the interface 16. The portable data carrier may take various forms, such as a magnetic card, a smart card, a flash memory for plugging into a socket of the interface 16, a mechanical key for inserting in a lock of the interface 16, an RFID transponder, or the like.

As a further alternative, biometric methods may be used for identifying the driver, such as detecting the driver's face using the above mentioned camera and comparing the detected face to face patterns of authorized drivers stored in a memory of the master controller 11, or detecting the driver's voice using a microphone and comparing the voice to predetermined voice patterns of authorized drivers.

If the driver was identified successfully in step S1, the master controller 11 checks the degree of authorization of the identified driver in step S2. Only if the identified driver has a master status, the method will proceed to step S3, otherwise, it proceeds directly to step S12, which will be described at a later stage. In this way, unauthorized drivers (e.g., inexperienced beginners, temporary users etc.) can be prevented from carrying out the operations described below referring to steps S4 to S11.

In step S4, the master driver is given an opportunity to specify whether he wishes to edit decision functions on which the operation of the master controller 11 during driving is based. If the driver's input is no, the method proceeds to step S12, if it is yes, it proceeds to step S5 in which the driver is allowed to select a setting parameter of any of the sub controllers 3, 6, 7, 10 which he/she wishes to edit. As the setting parameter, the user can select, for example, the gear ratio of gearbox 8, which is specified by a decision function depending on the rotation speed of the engine. This decision function is defined by a number of thresholds of the engine speed, which may be functions of the engine load, at which the transmission controller 7 steps up or down by one gear. If the gear ratio is selected as the setting parameter in step S5, the method branches from step S6 to step S7, where current values of said thresholds are displayed to the driver, and the driver is allowed to modify these within predetermined limits. When the driver has finished editing the thresholds, his selection is accepted in the step S8, and the master controller 11 determines in step S9, according to built-in rules, what setting ranges are still available for the other setting parameters. In this way, the driver is prevented from manipulating a decision function in a way that might jeopardize the safety of operation of the vehicle.

In step S11, the master controller 11 decides whether there is a setting parameter left which has not yet been edited by the driver, or whether previous selections for other parameters have reduced the setting ranges for the yet unedited setting parameters to such a degree that there is no more freedom of choice left for these. In either case, the method proceeds to step S12. If there are unedited setting parameters, and there is still a freedom of choice for these, the method returns to step S5, in which the driver selects the next parameter to be edited. Let us suppose that the next setting parameter selected in step S5 is the stiffness or damping of the shock absorbers, which is controlled by the suspension controller according to vehicle lateral speed or yaw rate. Here, the driver can be allowed to choose in step S6 whether he wishes to see displayed and to edit thresholds of the operating parameters (i.e., the longitudinal and lateral speed or the yaw rate, at which the suspension controller switches between different discrete levels of stiffness), in which case the method again branches to step S7, or whether he wishes to see displayed and to edit the degree of stiffness of the shock absorbers in each range defined by these thresholds, in which case the method proceeds to step S8.

FIG. 3 illustrates the effects of editing an exemplary decision function D(O) by carrying out either step S7 or S8. An initial decision function represented by a solid curve has three discrete values S1, S2, S3 of a setting parameter such as e.g. shock absorber rigidity S and two thresholds O1 O2 of an operating parameter O such as the yaw rate. By editing the thresholds O1, O2, the graph of the decision function is distorted horizontally, yielding decision function D′ represented by a dashed line in FIG. 3, whereas editing the setting parameters distorts the decision function D vertically, yielding e.g. dash-dot curve D″.

When the driver has carried out the desired changes, either in step S7 or in step S8, these changes are accepted in step S9, and the master controller determines again in step S10 whether the setting range of any of the yet unedited parameters has to be reduced.

Examples of other setting parameters, the decision function of which may be edited in further iterations of steps S4 to S11 are the operating mode of the Active Front Steering functionality, the degree of driver assistance provided by the power steering controller 3, the operating mode of the transmission controller 7, and the brake controller.

In case of the operating mode of the Active Front Steering functionality, the driver may select one or more ratios between the steering wheel angle and the yaw angle of the front wheels as a setting parameter, or modify thresholds of an operating parameter (e.g., vehicle speed) for switching over between different ratios.

In case of the degree of driver assistance, the decision function may be characterized by one or more ratios between the torque applied to the front wheels and the counter-torque felt by the driver, which may be selected by the driver, and by thresholds of an operating parameter (e.g., vehicle speed) for switching over between the different ratios.

Concerning the operating mode of the transmission controller, there may be provided various processes for automatically determining the transmission ratio depending on vehicle speed and load, as mentioned above, between which the driver is allowed to choose. Alternatively, the driver can be given the opportunity to create an algorithm himself by editing the switching thresholds.

When it is found in step S11 that there are no editable setting parameters left, the method proceeds to step S12. The decision functions modified in steps S4 to S11 may be associated exclusively to the master driver, or in an additional step S11′, the master driver can be given the opportunity to specify another driver to whom he wishes the edited decision functions to be associated.

In step S12, the method enters a driving mode (i.e., the engine is allowed to start) and operating parameters of the vehicle, such as longitudinal speed, lateral speed, yaw rate, pitch rate, steering wheel rotating speed, accelerator pedal position, brake pedal position or time derivatives of any of these, are determined in step S12. The master controller 11 chooses one of the setting parameters in step S13. In step S14, the master controller 11 evaluates the decision function of the setting parameter chosen in step S13 associated to the driver identified in step S1. In step S15, the method will return to step S13 as long there is a setting parameter for which the decision function has not been evaluated. When all decision functions have been evaluated, the method proceeds to step S16, wherein all setting parameters are set simultaneously in the various sub-controllers. By changing all setting parameters at the same time, transient states are avoided in which the setting parameters of the sub-controllers might be ill-adapted to each other.

While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit scope, applicability, or configuration in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

Claims

1. A method for controlling at least one setting parameter in at least one active subsystem in a chassis of a vehicle, comprising the steps of

determining an operating parameters of the vehicle;

evaluating a decision function that yields a value of said at least one setting parameter corresponding to said determined operating parameter; and

setting said value in said at least one active subsystem,

wherein the step of setting said valued comprises the step of identifying a driver and selecting the decision function associated to the driver from a set of predetermined decision functions.

2. The method of claim 1, wherein each of the predetermined decision functions yields a plurality of discrete values, and there is a threshold for said operating parameters, the decision function yielding for result a first one of said plurality of discrete values if the first operating parameter is below the threshold and a second one of said plurality of discrete values if the operating parameter is above the threshold, and the threshold is dependent on the driver.

3. The method of claim 1, wherein each of the predetermined decision functions yields for result a plurality of discrete values, and there is a threshold for said operating parameters, the decision function yielding for result a first one of said plurality of discrete values if the first operating parameter is below the threshold and a second one of said plurality of discrete values if the operating parameter is above the threshold, and at least one of said first discrete values and second discrete values is dependent on the driver.

4. The method of claim 2, wherein a number of subsystems is at least two, and wherein the predetermined decision functions associated to each subsystem have at least substantially identical thresholds.

5. The method of any of claim 1, wherein said operating parameters comprise one or more of

vehicle longitudinal speed,

vehicle lateral speed,

vehicle yaw rated,

vehicle pitch rate,

steering wheel rotating speed,

accelerator pedal position,

brake pedal position; or

time derivatives of any of the above.

6. The method of claim 1 wherein said at least one active subsystem is one of the following:

an all-wheel drive controller, at least one state of which corresponds to an all-wheel drive mode being on, and at least one state of which corresponds to the all-wheel drive mode being off.

7. The method of claim 1, wherein the driver is identified based on a driver input at a user interface.

8. The method of claim 1, further comprising the step of determining a set of decision functions based on an input from the driver.

9. A motor vehicle comprising:

a chassis having at least one active subsystem;

a controller for controlling at least one setting parameter in said at least one active subsystem, wherein the controller is adapted to:

determine an operating condition parameters of the motor vehicle;

evaluate a decision function which yields a value of said at least one setting parameter corresponding to said operating condition parameters; and

set said value in said at least one active subsystem,

an identifier adapted to identify a driver of the motor vehicle, and

a selector adapted to select the decision function associated to the driver from a set of predetermined decision functions.

10. The motor vehicle of claim 9, further comprising a user interface for assisting the driver in defining said set of predetermined decision functions.

11. A computer readable medium embodying a computer program product comprising:

a program the program configured to:

determine an operating parameter of the vehicle;

determine an operating parameter of the vehicle;

evaluate a decision function that yields a value of said at least one setting parameter corresponding to said operating parameter; and

set said value in said at least one active subsystem.

wherein the step of setting said value comprises the step of identifying a driver and selecting the decision function associated to the driver from a set of predetermined decision functions.

12. (canceled)

13. The method of claim 1, wherein said at least one active subsystem is a shock absorber controller, states of which correspond to different degrees of shock damping.

14. The method of claim 1, wherein said at least one active subsystem is a power steering controller, states of which differ by a degree of driver assistance.

15. The method of claim 1, wherein said at least one active subsystem is a steering controller, states of which have different relations between steering wheel and front wheel turning angles.

16. The method of claim 1, wherein said at least one active subsystem is a powertrain controller, states of which have different gear shifting characteristics.

17. The method of claim 1, wherein said at least one active subsystem is a load controller for controlling motor load according to an accelerator pedal position, states of which correspond to different pedal position/load characteristics,

18. The method of claim 1, wherein said at least one active subsystem is a brake controller.

19. The method of claim 1, wherein the driver is identified based on a driver input with biometric recognition.