Operating device for steering a vehicle and method for steering the vehicle

An operating device for steering a vehicle, in particular a motor vehicle, and a method for steering the vehicle by way of the operating device. The operating device comprises a control stick, in particular for operation by a human hand. The control stick has at least one degree of freedom. A steering angle can be specified by way of the control stick. The operating device comprises a control element. The specifiable steering angle can be determined as a function of a state of the control stick and as a function of a state of the control element.

BACKGROUND OF THE INVENTION

The invention relates to an operating device for steering a vehicle and to a method for steering the vehicle.

The use of a control stick for transverse guidance of a vehicle is known. Such a control stick can be used in conjunction with an electric power steering (EPS) system, or also in conjunction with a steer-by-wire (SBW) steering system. The state of the control stick thus determines a steering angle that is specified to the steering system.

It is further known that operating the control stick during long trips, for example when driving on a highway, results in symptoms of fatigue of the driver's hand.

Therefore, it is the object of the invention to improve the driving comfort when steering by way of a control stick and to prevent symptoms of fatigue of the driver's hand.

SUMMARY OF THE INVENTION

Characteristics that are important to the invention can further be found in the following description and in the drawings, wherein the characteristics can be important for the invention both alone and in various combinations, without further explicit reference being made thereto. By additionally providing a control element, and by determining a steering angle that can be specified to a steering system as a function of the state of the control stick and as a function of a state of the control element, transverse guidance is no longer solely dependent on the state of the control stick, but the state of the control element is also taken into consideration. This creates an additional option for the driver to influence the steering angle for the steering system. As a result, an alternative for operating the control stick is created, and fatigue of the driver's hand is precluded.

In an advantageous embodiment of the operating device, the control element is disposed on the control stick. This advantageously improves the operation of the control stick because the hand of the vehicle driver remains on the control stick during operation of the control element. This increases the safety, while improving the operating comfort, because the control stick can be in a zero position and the control element is operated with only one finger to carry out minor corrections when driving the vehicle straight ahead. As a result, it is not necessary to move the entire control stick.

In a further alternative embodiment of the operating device, the control element is disposed on a console in the region of the control stick. For this purpose, the hand may be located on, or in the region of, the control stick, and the control element can be operated while the hand is resting, for example using a finger. This results in the same advantages with respect to operating comfort and operating safety as with the above-mentioned embodiment.

In a further advantageous embodiment, the control element has a single degree of freedom. This advantageously results in easy operation of the control element, and the steering angle for the steering system can be specified by the vehicle driver in a fault-free manner.

In a further advantageous embodiment, a restoring mechanism is associated with the control element, the mechanism being designed to move the control element from a deflection position, which corresponds to a steering state of the control element, back to the zero position thereof. If the control element is operated by the vehicle driver, which is to say is brought into the deflection position thereof, and thus into a steering state, this state has an effect on the steering angle that is specified to the steering system. Because during non-operation, which is to say when no force is applied by the vehicle driver, the control element is moved back into the zero position thereof, the vehicle driver receives haptic feedback, which conveys to the vehicle driver that an operation of the control element will only result in a correction of the straight-ahead travel.

In an advantageous embodiment of the method, the control stick is essentially in a zero position, and the control element is essentially in the steering position thereof. For this purpose, a third signal, which corresponds to a specifiable steering angle, is essentially determined from a second signal, which is formed as a function of the steering position of the control element. A first signal, which is determined as a function of a state of the control stick, does not play a role for the steering angle in this context insofar as the control stick is essentially in the zero position thereof. As a result, advantageously only the control element must be moved to correct the specified steering angle, and the control stick itself can remain in the zero position. This embodiment corresponds to a first operating mode of the operating device.

In a further embodiment of the method corresponding to a second operating mode of the operating device, both the control stick and the control element are in a steering state. For this purpose, the third signal is essentially determined from the first signal and the second signal. The steering states of the control stick and of the control element are thus advantageously superimposed, and the control element can be used to correct the steering angle specified by the control stick, whereby the operating comfort of the operating device is increased.

In an advantageous embodiment of the method, a magnitude of the slope of the second signal, which is to say a change of the second signal over time, is limited by a change threshold value. This advantageously prevents the steering system from carrying out major steering maneuvers, such as those that can be triggered by the control stick, for example, by way of the control element.

In a further advantageous embodiment, the second signal is limited by a threshold value. As described above, this has the advantage that the control element can only be used to perform corrections of the specified steering angle.

Additional characteristics, application options and advantages of the present invention will be apparent from the following description of exemplary embodiments of the invention, which are illustrated in the figures. All of the described or illustrated characteristics, either alone or in any arbitrary combination, form the subject matter of the invention, regardless of the combination thereof in the claims or the dependency reference thereof, as well as regardless of the formulation or illustration thereof in the description or drawings. Identical reference numerals are used for functionally equivalent variables in all the figures, even if the embodiments are different.

Exemplary embodiments of the invention will be described hereafter with reference to the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a schematic block diagram2including an operating device4and a steering system6. A control unit8is located between the operating device4and the steering system6. The operating device4is used to steer a vehicle, in particular a motor vehicle, by way of the steering system6and by way of the control unit8. The operating device4comprises a control stick10and a control element12.

A first signal14is determined as a function of a state of the control stick10. A second signal16is determined as a function of a state of the control element12. The state of the control stick10and the state of the control element12each correspond to a position of the control stick10or of the control element12with respect to a respective reference. The first signal14and the second signal16are supplied to a functional block18of the control unit8. A third signal20is determined as a function of the first signal14and as a function of the second signal16. Using the third signal20, a steering angle, which hereafter inFIG. 5is denoted by the reference symbol α, can be supplied or specified to the steering system6by the functional block18or by the control unit8. In one form, which is not shown, the steering system6comprises at least one actuator, which sets a steering position of at least one wheel of a vehicle as a function of the third signal20, and thus as a function of the specified steering angle α.

The operating device4is operated by the driver of the vehicle. The vehicle driver can, for example, influence a state of the control stick10and a state of the control element12. As described, the state of the control stick10relates to a position of the control stick10, for example pivoting about an axis. The state of the control element12corresponds to a position of the control element12, for example. The first signal14is generated as a function of the state or the position of the control stick10. The second signal16is generated as a function of the state or the position of the control element12. The functional block18determines the third signal20from the first signal14and the second signal16.

In one form, which is not shown, additional signals can be supplied to the functional block18, for example the first signal14, or the second signal16, can be superimposed with additional signals for driving safety functions and, as a result, can remain unconsidered at times, for example in a critical driving state, wherein the third signal20is generated by a further functional block, or the functional block18, independently of the first signal14or the second signal16. In an alternative embodiment, the control element12can be designed so that the state of the control element12does not refer to a position of the control element12, but to the state of a tactile sensor, for example. As an alternative to the functional block18of the control unit8, the signals14and16can, of course, also be merged and combined in a different manner, for example by way of analog circuits.

FIG. 2shows a schematic side view of the control stick10. The control stick10extends along an axis22. The control stick10is intended for operation by a human hand. The control stick10comprises a first button36, a second button38, and the control element12toward a free end34. The axis22, together with further axes24and26, forms a three-dimensional Cartesian coordinate system. The control stick10is mounted counter to the direction of the axis22and below a line28by way of an associated bearing means, which is not shown, and has at least one degree of freedom. This degree of freedom can refer to a pivotability about the axis24, for example. Of course the degree of freedom can also refer to a pivotability relative to the axis22of the axis26. Further patterns of movement for the control stick10are, of course, also conceivable. The control stick10may also have several degrees of freedom. A region30is provided for pivoting, and thus for operating the control stick10. So as to operate the control stick10, the human hand moves toward the region30in a direction32and the hand clasps the control stick10.

The control element12is designed as a turning wheel inFIG. 2. The control element12designed as a turning wheel is mounted rotatably about a rotational axis40in accordance with the double arrow42. The control element12designed as a turning wheel further comprises a restoring mechanism, which is not shown and which is designed to always move the control element12designed as a turning wheel back to essentially the zero position after a deflection, which is brought about by the thumb of the human hand, for example. The restoring mechanism may be implemented by one or more spring elements, for example. As an alternative, the restoring mechanism is implemented by an actively controlled drive, for example a motor. A restoring mechanism, which is designed to move the control element12from a deflection position back to the zero position, is thus associated with the control element12. The control element12has a single degree of freedom. The degree of freedom is a rotational degree of freedom about the rotational axis40in accordance with the double arrow42. The control element12is disposed laterally on the control stick10toward the free end34of the control stick10. As an alternative, the control element12may also be disposed in a different position of the control stick10, for example counter to the axis22directly at the free end34.

As an alternative to disposing the control element12on the control stick10, the control element12may also be disposed in a region of the control stick10, which is to say in the vicinity of the control stick10on a console. The control element12is thus disposed in a region of the control stick10that can be reached by a finger, for example, while the hand is resting. For example, if the hand is moved to the control stick10in the direction32, with respect toFIGS. 2 and 3, the control element12can be disposed on the side of the control stick10counter to the direction26with respect to the control stick10so as to be operated by the index finger, for example. In an additional orientation of the arrangement of the control element12counter to the direction24with respect to the control stick10, the hand can still at least partially clasp the control stick10. This allows for a fast and secure operation of the control stick10when appropriate steering is required or in an appropriate driving situation.

FIG. 3shows a schematic side view of the control stick10in a further embodiment.FIG. 3essentially differs fromFIG. 2only in the design of the control element12. The comments provided forFIG. 2can thus be substantially applied toFIG. 3. The control element12inFIG. 3comprises an operating section44, which can be used to vary the position of the control element12in accordance with the double arrow46. The control element12ofFIG. 3will be described in more detail hereafter inFIG. 4.

FIG. 4shows the embodiment of the control element12according toFIG. 3. The control element12can be rotated about a rotational axis50by operating the operating section44in accordance with the double arrow48. The rotational axis50is located within a housing of the control stick10in the embodiment according toFIG. 3. The wall of the housing of the control stick10is denoted by reference numeral52. The control element12according toFIG. 4thus has a single rotational degree of freedom.

As an alternative to the single rotational degree of freedom, the control element12can also have a single translatory degree of freedom. In this alternative embodiment of the control element12, this element, for example as shown in the side view inFIG. 3, comprises an operating section44, which can be displaced in translation, by way of the operating section44, along an axis, in particular a longitudinal axis of the control element12. In this alternative embodiment, the control element12can also be referred to as a sliding element.

FIG. 5shows a schematic time diagram54with a curve56of the steering angle indicated by reference symbol α. The times58,60,62and64are plotted along a time axis t. The steering angle α of 0°, or zero degrees, is plotted along an axis for the steering angle α, which substantially corresponds to the vehicle driving straight ahead.

Up until the time58, the curve56remains at the steering angle α of 0°. In this case, the control stick10is located in the zero position thereof, and the control element12is likewise located in the zero position thereof. In conjunction withFIG. 1, the first signal14thus essentially indicates straight-ahead travel, and the second signal16likewise essentially indicates straight-ahead travel. The functional block18generates the third signal20in a corresponding manner, which thus essentially corresponds to the curve56up until the time58.

Proceeding from the time58, the curve rises up until the time60, essentially remains at a constant level up until the time62and, proceeding from the time62, decreases up until the time64, passing the steering angle α of 0°. The magnitude of the slope of the curve56in the region between the times58and60essentially corresponds to the magnitude of the curve56in the region between the times62and64. Up until the time64, the control stick10remains in the zero position thereof, so that the first signal14ofFIG. 1essentially corresponds to the steering angle α of 0°. The state of the control stick10thus essentially corresponds to the vehicle driving straight ahead. In contrast, the control element12is in a steering position, so that the second signal ofFIG. 1essentially corresponds to a steering angle different from 0°. The control element12is thus in a steering state at least part of the time. The third signal20ofFIG. 1is thus essentially determined from the second signal16, or essentially as a function of the second signal16.

The magnitude of the slope of the second signal16ofFIG. 1, which is to say the change of the second signal16over time, in particular the angular change over time, is limited by a change threshold value. As an alternative or in addition, the magnitude of the second signal16ofFIG. 1can be limited by a threshold value. The first signal14may take on magnitudes or absolute values greater than the aforementioned threshold value for this purpose. The magnitudes or absolute values of the slope of the first signal14may take on greater values than the change threshold value with respect to the second signal16. The control element12is thus particularly suited to pass on minor corrections with respect to the specified steering angle α to the steering system6. In contrast, major corrections of the steering angle α must be specified by way of the control stick10.

Proceeding from the time64, the curve56decreases up until the time65with a magnitude of the slope greater than the magnitude of the slope of the curve in the region between the times62and64. After the time65, the curve56remains at a substantially constant value. Up until the time64, only the control element12is in a steering state, the control stick10remaining in the zero position thereof, and thus not being in a steering state. In contrast, the control stick10is in the steering state thereof in the region between the times64and65, so that the first signal14ofFIG. 1essentially corresponds to a value of the steering angle α different from 0°. The control element12is also in the steering state thereof in the region between the times64and65, so that the second signal16ofFIG. 1essentially corresponds to a steering angle α different from 0°. The functional block18ofFIG. 1then ensures that the first signal14and the second signal16are superimposed and the curve56between the times64and65is set. In the region between the times64and65, the control stick10must be in the steering state because the steering state of the control element12, as compared to the steering state of the control stick10, has only limited impact on the steering angle α. In particular, the slope of the curve of the steering angle α or the value of the steering angle α, is limited as a function of the state of the control element12. Because the operation of the control element12alone between the time62and the time64, is no longer sufficient, depending on the driving situation when driving in a curve, so that after the time64, the control stick10likewise must be operated and transferred to the steering position thereof.

As an alternative to the described relationships between the time64and the time65, the control element12may also be in the zero position thereof and/or the second signal16may be disregarded between the times64and65in the determination of the third signal20. According to this alternative embodiment, the state of the control element12is not considered in a steering state of the control stick10.

With respect to the determination of the signal16ofFIG. 1, there are two options. Hereafter, it is assumed that the control stick10is in the zero position thereof. If the vehicle driver transfers the control element12into the steering state thereof, the third signal20is determined in keeping with the deflection of the control element12, and thus as a function of the second signal16. In the first option for determining the third signal20, the third signal20returns to the state prior to the deflection of the control element12, when the control element12is released, following the deflection thereof, and automatically returns to the zero position thereof by way of the restoring mechanism. In the second option of executing the second signal16or the third signal20, the third signal20remains at a value that is derived from the deflection of the control element12and the duration of the deflection of the control element12, after the control element12has been released and returned to the zero position thereof.

Between the times58and60, and between the times62and64, the operating device4is in a first operating mode. The operating device4is in a second operating mode between the times64and65.

The methods described above can be carried out as computer programs for a digital arithmetic unit. The digital arithmetic unit is adapted to carry out the above-described methods as computer programs. The operating device4is provided in particular for a motor vehicle and, together with the steering system6, is associated with the control unit8, which comprises the digital arithmetic unit, in particular a microprocessor. The control unit8comprises a storage medium on which the computer program is stored.