Method of operating a vehicle having an auxiliary steering system and

Abstract

The present disclosure generally relates to a method (50) for operating a vehicle (10) having an auxiliary steering system (12), and an auxiliary steering system (12) for a vehicle. The vehicle (10) has a plurality of drive units (18) and / or deceleration devices (20) associated with respective wheels (16) of the vehicle (10). A malfunction of an electronic steering system (14) of a vehicle (10) is detected. The auxiliary steering system (12) is activated on the basis of the plurality of drive units (18) and / or the reduction gear (20). The auxiliary steering system (12) has a control device (40, 44) which, by means of torque control, enables lateral control of the vehicle (10) by means of different wheel-specific torques of the plurality of drive units (18) and / or of the reduction gear (20). At least one steering angle or a corresponding measured variable of the wheel (16) is recorded by an additional sensor (30) of the auxiliary steering system (12), the additional sensor is associated with the wheel (16), and the recorded steering angle or the corresponding measured variable is forwarded to a control device (40, 44) of the auxiliary steering system (12).

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to a method for operating a vehicle with an auxiliary steering system and an auxiliary steering system of a vehicle. BACKGROUND

[0002] Electronic steering systems are an emerging steering technology in which the mechanical connection between the steering wheel and the wheels is dispensed with, instead two actuators are used: an actuator at the steering wheel which generates a torque to be fed back to the driver, and a wheel actuator which adjusts the wheels to the desired position.

[0003] Since a failure of the electronic steering system can lead to a loss of steering ability, the steering system as a whole must be designed with sufficient redundancy to ensure that the vehicle is always brought into a desired state, for example to drive at very low speed (“creep speed”).

[0004] After an initial failure, an electronic steering system that only provides one redundancy level can quickly (i.e. within a few minutes or even faster) force the vehicle into a creep state, thus reducing the functionality of the vehicle. In addition, such a transition means a major system change in terms of vehicle control for the driver. This can lead to an automatic reduction in vehicle speed or even to a standstill, for example. Therefore, it is desirable to provide additional redundancy so that the vehicle can still be maneuvered at least.

[0005] One option to add redundancy to the lateral control of the vehicle is to use other vehicle actuators (such as drive units and / or deceleration devices), which can generate wheel-specific torques. The lateral control of the vehicle (so-called third level lateral control or TLC) is achieved by controlling different torques via the drive units and / or deceleration devices, hereinafter referred to as auxiliary steering system.

[0006] It is known to use such redundancy when the conventional steering system can no longer provide sufficient lateral control, for example in the event of a complete failure of the electronic steering system (see DE 10 2022 103 808 A1, DE 10 2018 212 804 A1 and DE 10 2019 129 032 A1). In addition, it is known to adapt the functionality of the steering system due to a recorded fault (see US 11,318,962 B2 and US 11,780,493 B2).

[0007] An assisted steering system requires information related to the steering wheel angle, i.e. the steering angle input by the driver, to determine the desired direction of the vehicle. Conventionally, the assisted steering system also uses information related to the actual wheel angle to adjust the wheels to the desired position, thereby complying with the driver's input. According to previous approaches, it is known to obtain information related to the actual wheel angle by means of measurements by means of components of a conventional steering system of the vehicle, e.g. in the printed document. This information is also required in case of a failure of the conventional electronic steering system. Thus, it can occur that the conventional electronic steering system can no longer provide the information, e.g. because the failure is related to the measurement of the wheel angle, or because the control device fails. Furthermore, in case the information is provided by the conventional electronic steering system, it is unclear whether the information is reliable in case of a failure.

[0008] In an alternative, the information can also be obtained by means of an estimation by means of vehicle data, such as wheel speed, yaw rate, etc. However, in this case, a relatively complex estimation procedure is required, which slows down the transmission of the information and which can only obtain the information inaccurately - e.g. in case of a severe wheel slip which usually occurs when using the assisted steering system. Thus, the accuracy of the lateral control of the vehicle is limited. Furthermore, the complexity of the estimation procedure is high, which makes the system complex and costly.

[0009] Thus, there is a need to overcome or at least reduce the disadvantages of the known approaches and the assisted steering system. In particular, there is a need to provide a method and an assisted steering system, wherein the accuracy of the lateral control of the vehicle is improved compared to previous approaches in case of a failure of the electronic steering system of the vehicle. SUMMARY

[0010] This object is achieved by the subject matter of the independent claims. Advantageous configurations are indicated in the dependent claims and the following description, each of which can represent aspects of the present disclosure independently or in (sub-)combination. Some features are explained for a method, other features are explained for an apparatus. However, the respective aspects can be transferred to each other in the respective way.

[0011] According to one aspect, some embodiments of the present disclosure relate to a method for operating a vehicle having an assisted steering system. The vehicle has one or more drive units and / or reduction devices which are associated with respective wheels of the vehicle. The method comprises at least the following steps: detecting a failure of an electronic steering system of the vehicle.

[0012] An auxiliary steering system is activated on the basis of one or more drive units and / or reduction gears. The auxiliary steering system has a control device which, by means of torque control (also referred to as torque vectoring by third level lateral control, TLC), effects lateral control of the vehicle by means of different wheel-specific torques of the plurality of drive units and / or reduction gears.

[0013] At least one steering angle or a corresponding measured variable of a wheel is recorded by means of at least one additional sensor of the auxiliary steering system. The additional sensor is associated with the wheel and forwards the recorded steering angle or the corresponding measured variable to the control device of the auxiliary steering system.

[0014] The wheel-specific torque control which is carried out by the auxiliary steering system in order to achieve lateral control of the vehicle can therefore advantageously be carried out independently of the conventional electronic steering system of the vehicle. Information relating to the steering angle of at least one wheel can be recorded by means of the additional sensor independently of the conventional electronic steering system. It is therefore possible to avoid an estimation of information relating to the steering angle by means of an estimation routine. The precision of the lateral control of the vehicle which is carried out by means of the wheel-specific torque control is therefore particularly high, for example, since the direct recording of the steering angle by means of the additional sensor leads to an increase in the precision of the measurement signal and a reduction in the recording interval compared to the case in which an estimation routine is used. Furthermore, the information relating to the steering angle of the wheel which is recorded by means of the additional sensor is also reliable, since it is not damaged or not generally affected by a fault in the conventional electronic steering system.

[0015] In this respect, it is possible to achieve lateral control of the vehicle with high precision and low complexity, since complex estimation routines can be dispensed with.

[0016] According to a further aspect, some embodiments of the present disclosure also relate to an auxiliary steering system of a vehicle. The vehicle comprises a plurality of wheels and one or more drive units and / or reduction gears. The one or more drive units and / or reduction gears are each associated with at least one wheel and are designed to apply a respective wheel-specific torque to the at least one wheel. The auxiliary steering system comprises a control device and at least one additional sensor. The additional sensor is associated with a wheel and is designed to record an angular position of the wheel (referred to as camber angle, also referred to as wheel angle) or a corresponding measured variable and to forward it to the control device of the auxiliary steering system. The control device is designed to activate the auxiliary steering system in the event of a fault in an electronic steering system of the vehicle and to effect lateral control on the basis of torque control. The torque control is designed such that actuating signals can be output to the one or more drive units (for example phase voltages) and / or reduction gears, so that they output wheel-specific torques to the wheels which are respectively associated with them.

[0017] The advantages achieved by the method described herein are likewise achieved by the auxiliary steering system in a corresponding manner.

[0018] In particular, the electronic steering system can be understood as a steer-by-wire (SbW) steering system.

[0019] The electronic steering system of the vehicle herein is understood as a conventional electronic steering system of the vehicle, not an auxiliary steering system (an auxiliary steering system is only activated by torque control of the drive units and / or deceleration devices associated with the individual wheels), i.e. not a TLC.

[0020] The lateral control of the vehicle can optionally be based on a steering input from the driver (which is provided by the driver, for example, by means of a steering wheel), in order to steer the vehicle in a particular direction.

[0021] In the present case, the drive units are understood as respective operating electric motors, each of which is associated with at least one wheel and serves to drive the vehicle.

[0022] The malfunction of the electronic steering system can, for example, be caused by a malfunction of a steering system component (for example, a wheel actuator), which is detected or determined, for example, by a sensor of the electronic steering system. The malfunction herein does not necessarily mean a complete failure. The malfunction of the electronic steering system can also manifest itself in that the electronic steering system exhibits a functional degradation. For example, due to a malfunction (for example, of a control device), the electronic steering system can no longer be able to convert the steering input provided by the driver using the steering wheel sufficiently into a changed wheel angle (referred to as toe angle, also referred to as wheel direction). A malfunction can also occur when the function performed by a steering system component of the electronic steering system exceeds a prescribed normal range. For example, it can be prescribed that a sensor as a steering system component forwards measurement values within a defined range to a control device. However, when the forwarded measurement values exceed the range, the sensor (steering system component) can be considered to have a malfunction. Thus, steering system components that are still in operation can be recorded, although they have a malfunction, which ultimately provides an explanation for the malfunction of the electronic steering system.

[0023] An important factor is that the conventional electronic steering system can no longer be reliably used to sufficiently and reliably ensure the lateral control of the vehicle. This should be distinguished from the lateral control of the vehicle being insufficient due to external conditions, for example, in the case of icy roads resulting in severe wheel slip. In this sense, the conventional electronic system can have a control device that determines the malfunction, and due to the recording of the malfunction or the determination of the existence of the malfunction, the control device instructs the auxiliary steering system to continue the method described herein (activation of the auxiliary steering system).

[0024] In one alternative, the malfunction of the electronic steering system can also be recorded by a superior drive control device of the vehicle, which carries out a test function on the electronic steering system function. As will be explained in more detail below, the drive control device can also serve as a control device for the auxiliary steering system.

[0025] An auxiliary steering system is understood to be a system which only indirectly, i.e. by outputting different wheel-specific torques to the respective wheels, effects vehicle lateral control. Due to the geometry of the front axle (lever arm), this results in a resultant force on the steering lever of the front axle. As a result, the wheels of the front axle have different rotational speeds and thus set a toe angle. This toe angle can thus be adjusted by the auxiliary steering system in accordance with the driver input. Alternatively or additionally, a yaw moment can also be set by the rear axle with corresponding independently controlled wheel-specific torques, which causes a vehicle reaction corresponding to the driver input.

[0026] In general, for vehicle lateral control, at least multiple actuation inputs for different wheels are required to generate wheel-specific torques, which can cause a change in the recorded wheel steering angle and / or vehicle yaw moment.

[0027] In the present case, an additional sensor is understood to be a sensor which is not part of the conventional electronic steering system. An additional sensor is a sensor which is located outside and separate from the electronic steering system, independently of the electronic steering system. It goes without saying that, depending on the positioning of the additional sensor, the additional sensor can be mechanically coupled to components of the electronic steering system. However, the additional sensor is not a sensor of the kind which the electronic steering system normally records the steering angle of the wheels (referred to as toe angle, also referred to as wheel angle) and which forwards it to a control device in the electronic steering system. In particular, the additional sensor is separate from the electronic steering system, since the function of the additional sensor does not depend on the actuation signals or control signals which are forwarded by the control device of the electronic steering system. The additional sensor is also not coupled to the control device of the conventional electronic steering system. Thus, in the event of a fault in the electronic steering system, the additional sensor can be protected from damage due to the fault in the electronic steering system.

[0028] The vehicle is advantageously designed to ensure that the additional sensor is supplied with power independently of the electronic steering system. For example, the additional sensor can be coupled to a power supply circuit which does not depend on the function of the electronic steering system.

[0029] In the case of wheel-specific torque control of the auxiliary steering system, simplifications can be considered, for example assuming that the front wheels or the rear wheels of the vehicle are oriented in a corresponding pair-specific manner. For example, due to the different curve trajectories of the wheels on the inside of a curve relative to the wheels on the outside of a curve, the wheels on the inside of a curve generally have a different steering angle (wheel angle). However, depending on the vehicle speed and the wheel slip (which can be determined, for example, by a sensor, for example an additional sensor), the difference in the steering angle of the wheels, for example, is known. Thus, it is sufficient to provide only a single additional sensor for the auxiliary steering system. Ultimately, from the steering angle recorded by the at least one additional sensor, the steering angles of the other wheels can be estimated. This method is particularly compact as a result.

[0030] A plurality of additional sensors can optionally be provided, each of which is designed independently of one another to record a steering angle (toe angle, wheel angle) of the wheel associated therewith. The plurality of additional sensors can forward the recorded steering angles to the control device of the auxiliary steering system. As a result, the accuracy of the auxiliary steering system can be further improved, since the steering angles of the different wheels can be recorded and taken into account in the torque control.

[0031] In the present case, a deceleration device is understood to be a device associated with the wheel, which is designed to reduce the rotational speed of the wheel, for example by frictional contact with a friction disc.

[0032] In some embodiments, the additional sensors are designed to record the relative or absolute angular position of the wheel and to forward it to the control device of the auxiliary steering system. The absolute angular position of the wheel differs from the relative angular position of the wheel in that, in the case of the absolute angular position, a reference value is known, for example the zero position of the wheel or the straight-ahead position of the wheel corresponding to the conventional straight-ahead direction of the vehicle. However, it is often sufficient to record the relative angular position, taking into account the measurement data obtained from the additional sensors, for example, if the control device of the auxiliary steering system comprises the reference values for the respective wheels. For example, the respective reference values can be stored in a storage device coupled to the control device of the auxiliary steering system.

[0033] In this respect, the recording of at least one steering angle of the wheel by the additional sensors of the auxiliary steering system is also understood to mean an indirect recording. This means that the additional sensors can be designed to provide the control device of the auxiliary steering system with a measurement value by means of which the steering angle of the individual wheel or of a plurality of wheels can be determined indirectly. In this respect, the recording of the steering angle is not limited to the case in which the additional sensors must record the steering angle directly. Rather, the additional sensors can generally also record a direction, a position or a distance or other measured variables, which enable the determination of the steering angle since they correspond to the steering angle.

[0034] The control device preferably takes into account the reference angle values of the wheels. In this case, the additional sensors only need to be designed to record the relative angular position of the respective wheel associated therewith. As a result, the recording of the measurement values is a particularly simple process, which means that the complexity of the additional sensors is low.

[0035] In some embodiments, the electronic steering system of the vehicle comprises a front axle steering system and a rear axle steering system. Subsequently, a fault of the electronic steering system is detected for the front axle steering system or the rear axle steering system. Then, the auxiliary steering system is activated based on the one of the front axle steering system and the rear axle steering system which has not failed. In this embodiment, the control device implements the lateral control of the vehicle based on at least the one of the front axle steering system and the rear axle steering system which has not failed. Thus, the accuracy of the lateral control of the vehicle can be further improved. The one of the front axle steering system and the rear axle steering system which has failed can also be taken into account in order to implement the desired lateral control in combination with the wheel-specific torque, which is ensured by the respective drive unit and / or the reduction unit on the wheels of the failed front axle steering system or rear axle steering system by the auxiliary steering system.

[0036] Alternatively, the auxiliary steering system can also be implemented only by the rear axle steering system (in the event of a failure of the front axle steering system). The auxiliary steering system takes into account the current front axle angle to set the rear axle toe angle, which in turn also generates a vehicle reaction (lateral control of the vehicle) corresponding to the driver input.

[0037] The additional sensor can optionally be designed such that it can be coupled to different supply circuits. For example, the additional sensor can have a power supply switch which, depending on its switch position, enables the additional sensor to be coupled to different supply circuits. Thus, a redundancy with regard to the power supply of the additional sensor can be created, thereby increasing the availability of the method and the auxiliary steering system.

[0038] The additional sensor can be designed such that, when the supply by the first supply circuit is no longer ensured, there is an automatic switchover from the first supply circuit to the second supply circuit for supplying the additional sensor. For example, the additional sensor can also comprise a voltage sensor which is designed to record the supply voltage. Depending on the supply voltage recorded by the voltage sensor, the power supply switch can be switched to enable coupling to a particular supply circuit.

[0039] In some embodiments, the additional sensor has a sensor element, a sensor logic circuit, a communication interface and a power supply connection. By means of the power supply connection, the additional sensor can be coupled to a supply circuit for power supply. The communication interface enables communication between the additional sensor and an external device, for example the control device of the auxiliary steering system. The sensor logic circuit is able to evaluate the measurement data recorded by the additional sensor by means of the sensor element in order to output the respective measurement data or measurement values to the external device, for example the control device of the auxiliary steering system. The sensor element is able to record measurement values, for example of a component coupled thereto. The sensor element can be configured in various ways, for example a magnetic-based sensor element or an electrical-based sensor element, which is designed to record an orientation change or a position change of an external component, for example a mechanical component.

[0040] The sensor element can optionally be designed as a magnetic ring or a magnetic coil, in which a voltage is induced depending on a change in the position or movement (change in angle) of a recorded external component, for example a wheel.

[0041] The additional sensor is preferably designed as a pinion sensor. Thus, a known sensor type can be relied on, which reduces the complexity of the method and the vehicle. For example, the pinion sensor can have two different gears, which enable the rotational position of at least one pinion to be determined.

[0042] In other embodiments, the additional sensor can also be designed as a Hall sensor, which increases the compatibility of the method.

[0043] The additional sensor is optionally designed as a pinion sensor and is coupled to a pinion shaft. The additional sensor is in turn designed to record the pinion angle.

[0044] Alternatively, the additional sensor can also be designed as a linear sensor coupled to a steering rack. The additional sensor is in turn designed to record the stroke of the steering rack.

[0045] In another alternative, the additional sensor is designed as a rotary sensor and is coupled to a ball screw nut. The additional sensor is in turn designed to record the rotational speed of the ball screw nut.

[0046] Of course, various similar and / or different additional sensors are optionally part of the electronic steering system. Thus, the redundancy of the electronic steering system is increased. Thus, by means of the measured variable corresponding to the steering angle, the steering angle of the wheels (wheel angle, toe angle) can be recorded at least indirectly and reliably.

[0047] The control device of the auxiliary steering system can be designed to determine or at least estimate the absolute angular position of the wheels, for which the additional sensor forwards the measured values. For example, there is a fixed correlation between the position of the steering rack of the electronic steering system and the steering angle of the wheels coupled to the steering rack. This correlation can be used by the control device of the auxiliary steering system to determine the steering angle of at least one wheel of the vehicle, but optionally of more or all wheels.

[0048] The mechanical part of the additional sensor can also be a physical part of the electronic steering system. This means that the sensor element can be integrated in the electronic steering system. The integration is, however, simplified to a coupling with the mechanical components of the electronic steering system. The additional sensor is otherwise independent of the electronic steering system. This means that at least the sensor logic circuit, the communication interface and the power connection are independent of the electronic steering system, and therefore the additional sensor is also not affected by a failure of the electronic steering system. In particular, since the sensor logic circuit and the power supply are independent of the electronic steering system, the additional sensor is not affected by a control failure, a power supply failure of the electronic steering system or a system failure of the control device of the electronic system. A failure of the electronic steering system can therefore not propagate into the auxiliary steering system.

[0049] In some embodiments, the additional sensor can be coupled to a drive control device of the vehicle. The drive control device controls the drive units and / or the reduction devices for driving the vehicle. In this embodiment, the drive control device of the vehicle also performs the function of the control device of the auxiliary steering system. For example, the drive control device can generally be a control device which converts a speed input of a driver of the vehicle into a torque input, which is output to the respective drive units and / or reduction devices by means of actuation signals in order to drive the vehicle. In this case, a separate control device of the auxiliary steering system can be dispensed with, since its function is implemented in the drive control device. The auxiliary steering system and the vehicle are therefore particularly compact. Since the drive control device can also be designed to monitor the functioning and the occurrence of a failure of the electronic steering system, the vehicle can be particularly compact and the method (for example, in addition to the additional sensor) can not require any additional circuitry.

[0050] The determination of the position information of the external (mechanical) components recorded by the additional sensor can preferably take place within the additional sensor (for example within the sensor logic circuit) or by means of an external data processing device (for example the drive control device). The evaluation can include a diagnosis for ensuring the required integrity (also referred to as ASIL level) and a calculation of the relative and / or absolute information about the angular position of the wheels.

[0051] The additional sensor can also optionally be coupled to a vehicle bus (for example a CAN bus, Flexray, Ethernet or SENT bus) via an external control device (for example the drive control device). The compatibility of the method is therefore improved since an additional communication path and protocol for communication with other vehicle components is enabled.

[0052] The method is optionally designed as a computer-implemented method. This means that the method steps can be performed with the aid of one or more data processing devices. In particular, the failure detection of the electronic steering system, the activation of the auxiliary steering system and the recording of the at least one wheel angle can be carried out by means of data processing devices with the aid of one or more data processing devices.

[0053] According to other aspects, the disclosure also relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method described herein. The advantages achieved by the method described herein are also achieved in a corresponding manner by the computer program product.

[0054] According to other aspects, the disclosure also relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method described herein. The advantages achieved by the method described herein are also achieved in a corresponding manner by the computer program product.

[0055] According to other aspects, the disclosure also relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method described herein. The advantages achieved by the method described herein are also achieved in a corresponding manner by the computer program product.

[0056] In the context of the present disclosure, a vehicle can in particular comprise a land vehicle; i.e. an off-road vehicle and a road vehicle such as a car, a bus, a truck and other utility vehicles, among others. The vehicle can be manned or unmanned. The vehicle can be electrically driven at least some of the time and can have an internal combustion engine and / or an electric motor as a drive device.

[0057] All features explained with regard to the individual aspects can be combined with other aspects, alone or in (sub-)combination. BRIEF DESCRIPTION OF DRAWINGS

[0058] The present disclosure and further advantageous embodiments and developments thereof are described and explained in more detail below by means of examples shown in the drawings, in which: Figure 1 A simplified schematic diagram of a vehicle having an auxiliary steering system and an electronic steering system is shown according to an embodiment; Figures 2 to 5 A simplified diagram of additional sensors associated with an auxiliary steering system is shown according to different embodiments; and Figure 6 A simplified schematic diagram of a method for operating a vehicle having an auxiliary steering system and an electronic steering system is shown. DETAILED DESCRIPTION

[0059] The detailed description that follows, in conjunction with the accompanying drawings (in which like reference numerals represent like elements), is intended to describe various embodiments of the disclosed subject matter and not merely to represent a single embodiment. Each embodiment described in this disclosure serves only as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples included herein do not claim to be complete and do not limit the claimed subject matter to the precise form disclosed. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the described embodiments. Therefore, the described embodiments are not limited to the embodiments shown, but rather have the widest possible range of applications compatible with the principles and features disclosed herein.

[0060] All features disclosed below with respect to the exemplary embodiments and / or the accompanying drawings may be combined with features of various aspects of the present disclosure (including features of the preferred embodiment) alone or in any subcombination, provided that the resulting feature combination makes sense to a person skilled in the art.

[0061] For purposes of this disclosure, the phrase "at least one of A, B, and C" refers, for example, to (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all other possible combinations when three or more elements are listed. In other words, the phrase "at least one of A and B" generally refers to "A and / or B," i.e., only "A," only "B," or "A and B."

[0062] Figure 1 A simplified schematic diagram of a vehicle 10 having an assisted steering system 12 is shown according to one embodiment.

[0063] The vehicle 10 has an assisted steering system 12 and an electronic steering system 14. The electronic steering system 14 herein corresponds to a conventional steering system typically used for lateral control of the vehicle 10.

[0064] According to this embodiment, the vehicle 10 includes a front axle steering system 15A and a rear axle steering system 15B, both of which are designed for lateral control of the vehicle 10 .

[0065] Vehicle 10 includes wheels 16, 16A, 16B. According to the embodiment shown here, front wheels 16A and rear wheels 16B are steerable. This means that the direction of front wheels 16A and rear wheels 16B can be changed to achieve lateral control of the vehicle, in particular with the help of electronic steering system 14.

[0066] In other words, the lateral control of the vehicle 10 can be achieved by setting the steering angle (wheel angle, toe angle) for the front wheels 16A and / or the rear wheels 16B in a wheel-specific manner or in a coupled or fully coupled manner, respectively.

[0067] According to this embodiment, a drive unit 18, 18A, 18B is associated with a wheel 16. One drive unit 18 is associated with one wheel 16. The drive unit 18 is designed to apply a torque to the wheel 16 associated therewith in order to drive the vehicle 10.

[0068] According to this embodiment, a respective reduction device 20, 20A, 20B is also associated with a wheel 16. Herein, one reduction device 20 is associated with one wheel 16. The reduction device 20 is designed to apply a torque to the wheel 16 associated therewith in order to be able to reduce the speed of the vehicle 10.

[0069] In an alternative, the respective drive unit 18 and / or the reduction device 20 can also be associated only with a specific wheel 16.

[0070] Of course, for the purpose of driving, it is usually only necessary to provide a single drive unit 18C for each front or rear axle of the vehicle 10, which in turn drives the wheels 16 of the respective axle.

[0071] Alternatively or additionally, the drive unit 18 can also be used to achieve a reduction in the speed of the vehicle 10, so that electrical energy can be recovered.

[0072] The vehicle 10 also comprises a steering wheel 22, by means of which a driver of the vehicle 10 can provide a steering input for the lateral control of the vehicle 10. In order to record the steering input from the driver 10 of the vehicle, the vehicle 10 has a steering actuator 24 with feedback function.

[0073] The steerable wheels 16 of the axles of the vehicle 10 are coupled to one another via mechanical components 26, in this case steering racks 27. The steering racks 27 enable the wheels 16 to be deflected correspondingly with respect to a reference direction of the wheels 16. Herein, the reference direction of the wheels 16 is defined by the straight-ahead direction of the vehicle 10, which in this respect corresponds to the zero position direction of the steering angle of the wheels 16.

[0074] The electronic steering system 14 has a redundant steering actuator 28 for each steering rack, which is coupled to the steering rack 27. The redundant steering actuator 28 is designed to move the steering rack 27 from the zero position, so that a deflection of the wheel 16 with respect to the reference direction can be achieved.

[0075] Although the steering actuators 28 are shown herein in relation to two axles of the vehicle 10, the vehicle typically only needs to have a single steering rack 27 (e.g. only a single steering rack 27 on the front axle steering system 15A). This can be the case, for example, in a vehicle 10 without a rear axle steering system 15B.

[0076] The electronic steering system 14 also has at least one sensor 29, which serves to redundantly record the function of the steering actuators 28 and provides the electronic steering system 14 with feedback relating to the position of the steering rack 27. For example, two mutually redundant sensors 29 can be provided. The redundant steering actuators 28 can have a plurality of sensors 29, for example. Thus, the electronic steering system 14 can influence the orientation of the wheels 16 such that the steering input provided by means of the steering wheel 22 by the driver of the vehicle 10 is converted into a lateral control of the vehicle 10, i.e. a rotation of the vehicle 10 about a vehicle vertical axis. By means of the at least one sensor 29 of the electronic steering system 14, it can be checked whether the function of the electronic steering system 14 is ensured in actual agreement with the setpoint input provided by means of the steering wheel 22.

[0077] In an alternative embodiment, the electronic steering system 14 can also have at least two steering actuators 28, which set the steering angle (wheel angle, toe angle) of the wheels 16 per wheel. In this embodiment, a sensor 29 can also be provided, which is designed to record the steering angle of the different wheels 16.

[0078] The auxiliary steering system 12 has an additional sensor 30 in comparison with the at least one sensor 29 of the electronic steering system 14. The additional sensor 30 is separate from the sensors 29 (typically a plurality of sensors) of the electronic steering system 14. During operation of the electronic steering system 14, the additional sensor 30 is not used by the electronic steering system 14 for controlling the electronic steering system 14.

[0079] According to the embodiment shown herein, the additional sensor 30 is likewise coupled to the same mechanical component 26, i.e. the steering rack 27. However, in general, the additional sensor 30 can also be coupled to other mechanical components 26, which are capable of recording the steering angle of the steerable wheels 16 of the vehicle 10 or of recording a measurement corresponding to the steering angle, so that the steering angle can be determined.

[0080] The additional sensor 30 has a sensor element 32, a sensor logic circuit 34, a power supply connection 36 and a communication interface 38. The sensor element 32 is capable of recording a measured value of the external mechanical component 26, in this case the steering rack 27, to which the additional sensor 30 is coupled. In this regard, the sensor element 32 is designed to record a position change or movement of the external mechanical component, in this case the steering rack travel of the steering rack 27 relative to a reference position (zero position). The sensor logic circuit 34 is designed to evaluate the measured value recorded by the sensor element 32 and to provide the measured value to other components of the auxiliary steering system 12. The power supply connection 36 is designed to be capable of being coupled to an external switching circuit, thereby ensuring that the additional sensor 30 is supplied with power. The communication interface 38 is designed to be capable of communicating with external components of the vehicle 10.

[0081] According to the embodiment shown here, the vehicle 10 comprises a control device 40, which is part of the auxiliary steering system 12. The control device 40 has a data processing device 42. According to the embodiment shown here, the control device 40 is also coupled to an optional superordinate drive control device 44, between which and the control device 40 of the auxiliary steering system 12 bidirectional communication is possible. According to this embodiment, the superordinate drive control device 44 is not part of the auxiliary steering system 12, although it can be part of the auxiliary steering system 12 in other embodiments and can in turn take over the functions of the control device 40.

[0082] The superordinate drive control device 44 is only optional. It can also be omitted.

[0083] According to the embodiment shown here, the vehicle 10 also comprises a plurality of energy supply circuits 46, 46A, 46B, which are independent of one another here. According to the embodiment shown here, the energy supply connection 36 of the additional sensor 30 is designed to be selectively coupled to the plurality of energy supply circuits 46 at the same time in order to supply the additional sensor 30 with power. Thus, only one energy supply circuit 36 is always coupled to the additional sensor 30 for the purpose of power supply. However, since the energy supply connection 36 can be coupled to a plurality of energy supply circuits 46, it can be ensured that the additional sensor 30 is energy-supplied redundantly.

[0084] The additional sensor 30 can also optionally have an additional sensor element 32, which is redundant with respect to the sensor element 32 already shown here. In the event of a malfunction of the first sensor element 32 of the additional sensor 30, the measured value is recorded by means of the additional sensor element 32.

[0085] In the present case, according to a preferred configuration, the control device 40 of the auxiliary steering system 12 is coupled to the drive units 18 and the reduction devices 20 of the vehicle 10. According to this embodiment, the control device 40 of the auxiliary steering system 12 is additionally coupled to the rear axle steering system 15B as well. The control device 40 of the auxiliary steering system 12 is designed to function as a third level lateral control (TLC) of the vehicle 10. This means that a steering input provided by means of the steering wheel 22 can be converted into an indirect lateral control of the vehicle 10 by the control device 40 of the auxiliary steering system 12 on the basis of different wheel-specific torques. The different torques are ensured by means of corresponding actuation signals of the control device 40, which are output to the drive units 18 and / or the reduction devices 20 associated with the different wheels 16. Due to the corresponding actuation signals of the control device 40, the different wheel-specific torques are applied to the wheels 16 by the drive units 18 and / or the reduction devices 20. This indirectly leads to a rotation of the vehicle 10 about a vehicle vertical axis (due to an induced yaw moment), thus enabling a lateral control of the vehicle 10.

[0086] Alternatively or additionally, the control device 40 of the auxiliary steering system 12 is also designed to ensure a lateral control of the vehicle 10 by means of the rear axle steering system 15B on the basis of a steering input from the driver of the vehicle 10. This means that the steering angle of the wheels 16 of the rear axle steering system 15B can be controlled by the control device 40. To this end, the control device 40 can output corresponding actuation signals to the rear axle steering system 15B. This can be used in combination with the wheel-specific torques applied to the wheels 16 of the front axle steering system 15A.

[0087] In order to determine the actuation signals, the control device 40 has a torque control with feedback function, which takes into account, on the one hand, a steering input by means of the steering wheel 22 and, on the other hand, measured values recorded by means of the additional sensors 30. The control device 40 herein can be designed such that the actual direction of the steerable wheels 16 of the vehicle 10 is determined by the control device 40 on the basis of the measured values forwarded by the additional sensors 30.

[0088] In one alternative, the additional sensors 30 can also be designed such that they record the angular position of the steerable wheels 16 of the vehicle 10 indirectly, or determine the angular position by means of a sensor logic 34 and forward the angular position determined in this way to the control device 40.

[0089] It is important that the control device 40 is not based on a recording of measured values by means of at least one sensor 29 of the electronic steering system 14. Only a recording of measured values of the steering input provided by the driver by means of the steering wheel 22 is considered, without taking into account the steering angle-related measured values recorded by the electronic steering system 14 during normal operation. In contrast thereto, the torque control carried out by the control device 40 of the auxiliary steering system 12 is based on a recording of measured values by means of the additional sensor 30, which is separate from the electronic steering system 14 and thus independent of the electronic steering system 14. Furthermore, it is important that the additional sensor 30 is designed to record a variable which is indirectly equal to or corresponds to the steering angle of at least one steerable wheel 16 of the vehicle 10 or which enables the steering angle to be determined. The recorded or determined steering angle is then taken into account in the torque control by the control device 40 of the auxiliary steering system 12.

[0090] In some embodiments, of course, a plurality of additional sensors 30 can be provided, which are associated with the respective steerable wheels 16 of the vehicle 10.

[0091] Figures 2 to 5 Simplified schematic diagrams of the additional sensor 30 associated with the auxiliary steering system 12 according to different embodiments are shown. Only the respective differences are discussed herein.

[0092] The sensor element 32 is coupled to the mechanical component 26 and is designed to record a movement or a change in position of the mechanical component Figure 2 . The sensor element 32 can be designed, for example, as a Hall sensor, a magnetic ring, a magnetic coil, a position sensor, etc. Alternatively, the sensor element 32 can also be designed as a pinion sensor.

[0093] The additional sensor 30 can be coupled to different mechanical components 26, for example to at least one of a pinion shaft, a steering actuator of the electronic steering system 14, a steering rack 27 of the electronic steering system 14 and a ball screw nut of the electronic steering system 14.

[0094] The communication interface 38 is designed to enable bidirectional communication between the additional sensor 30 and external components, for example the control device 40 of the auxiliary steering system 12. Alternatively, the communication interface 38 of the additional sensor 30 can also be coupled to a superordinate drive control device 44, for example, which integrates the functions of the control device 40 of the auxiliary steering system 12 Figure 3 .

[0095] The energy supply connection 36 of the additional sensor 30 Figure 2 and Figure 3 is connected to an energy supply circuit 46.

[0096] The energy supply connection 36 of the additional sensor 30 is designed in such a way that it can be coupled to a plurality of energy supply circuits 46A, 46B of the vehicle 10 in order to supply the additional sensor 30 with energy Figure 4 To this end, the energy supply connection 36 can have, for example, a power switch 48 which selectively enables an actual current flow via a particular energy supply circuit 46. In the event that a particular energy supply circuit 46A is no longer available, the additional sensor 30 can be coupled to another energy supply circuit 46B depending on the switching position of the power switch 48. The control of the power switch 48 can be performed, for example, by the sensor logic circuit 34 of the additional sensor 30.

[0097] In an alternative, the energy supply of the additional sensor 30 can also be ensured directly by an external control device, for example the superordinate drive control device 44 Figure 5 In this case, the power switch 48 can be implemented directly in the superordinate drive control device 44 for coupling to the plurality of supply circuits 46. In this case, the superordinate drive control device 44 also takes over the control of the power switch 48 in order to selectively couple the additional sensor 30 to a particular energy supply circuit 46 for energy supply purposes. Although the power switch 48 herein is implemented in the superordinate drive control device 44, of course, the power switch 48 can alternatively also be implemented in the control device 40 of the auxiliary steering system 12, which is then separate from the superordinate drive control device 44.

[0098] The superordinate drive control device 44 can be designed to perform a torque control in order to drive and / or decelerate the vehicle 10 by means of the drive unit 18 and / or the deceleration device 20. This means that the basic driving functions for the propulsion of the vehicle 10 or the deceleration of the vehicle 10 are already performed by the superordinate drive control device 44. Since the superordinate drive control device 44 can also take over the control functions of the auxiliary steering system 12, the auxiliary steering system 12 has a particularly compact design and does not require additional components in addition to the additional sensor 30. The vehicle 10 is therefore particularly compact.

[0099] In the case of a vehicle 10 having a rear axle steering system 15B, the superordinate drive control device 44 can also perform the control functions of the rear axle steering system 15 in alternative embodiments.

[0100] Figure 6 A simplified schematic of a method 50 for operating a vehicle 10 having an auxiliary steering system 12 is shown. Optional steps are indicated in dashed lines.

[0101] In step S1, a malfunction of the electronic steering system 14 of the vehicle 10 is detected. This can be determined, for example, by means of the measured values recorded by at least one sensor 29 of the electronic steering system 14. The superordinate drive control device 44 can optionally perform a monitoring function on the functioning of the electronic steering system 14 of the vehicle 10. In other words, the superordinate drive control device 44 can be designed to monitor whether the electronic steering system 14 is functioning as intended. In one alternative, a functional fault of the electronic steering system 14 can also be determined by the control device 40 of the electronic steering system 14 itself, for example on the basis of the measured values recorded by means of the at least one sensor 29.

[0102] In the following step S2, the auxiliary steering system 12 is activated on the basis of the plurality of drive units 18 and / or the reduction devices 20. The auxiliary steering system here has a control device 40, which can optionally also be the superordinate drive control device 44, which, by means of torque control, effects a steering movement of the vehicle 10 by means of different wheel-specific torques of the plurality of drive units 18 and / or the reduction devices 20. To this end, the control device 40 outputs corresponding actuation signals to the drive units 18 and / or the reduction devices 20. On the basis of the different actuation signals, wheel-specific torques are applied to the wheels 16 of the vehicle 12, so that, as a result of the torque differences between the wheels 16, a yaw moment is generated, which leads to an indirect rotation of the vehicle 10 about the vehicle vertical axis. On the basis of the different actuation signals to the drive units 19 and / or the reduction devices 20 and the rear wheel steering system 15B (optionally or additionally), an indirect rotation of the vehicle 10 about the vehicle vertical axis can thus be induced. An indirect lateral control of the vehicle 10 is thus achieved by means of TLC.

[0103] In a further step S3 of the method 50, at least one steering angle of the wheels 16, in particular of the steerable wheels 16, is recorded by means of additional sensors 30 of the auxiliary steering system 12. The additional sensors are associated with the wheels 16 and forward the recorded steering angles to the control device 40 of the auxiliary steering system 12. Optionally, the recording of the measured values by means of the additional sensors 30 can also make the steering angles determinable indirectly, for example by means of the control device 40 or the sensor logic 34, from the recorded measured values.

[0104] Since the measured values on the steering angles of the steerable wheels are recorded in step S3, the control of the auxiliary steering system 12 is of course also adjusted accordingly to match the steering input. In this respect, step S3 returns to step S2.

[0105] The method 50 can optionally be refined (step S3A) in that, when the steering angle of at least one wheel 16 is recorded by means of the additional sensor 30, the relative or absolute angular position of the wheel 16 is recorded by the additional sensor 30 and forwarded to the control device 40 of the auxiliary steering system 12. This means that the additional sensor 30 does not necessarily have to be designed to record the absolute value of the measured variable. It is also sufficient for the relative value to be recorded for the measured variable to operate the TLC (auxiliary steering system 12) when the absolute value of the steering angle can be determined on the basis of the relative value.

[0106] Furthermore, the method 50 can also optionally be refined in that the control device 40 of the auxiliary steering system 12 takes into account a reference angle value of the wheel 16. Thus, it is sufficient for the additional sensor 30 to simply record the relative value of the steering angle or the respective variable. The reference angle value can correspond, for example, to the zero position (i.e. the straight-ahead position) of the steerable wheel 16. The reference angle value can already have been received by the electronic steering system 14 before the fault in the electronic steering system 14 is recorded.

[0107] The method 50 advantageously enables a high precision of the auxiliary steering system 12 (TLC) since, by means of the separate additional sensor 30, it can be ensured that a fault in the conventional electronic steering system 14 does not propagate to the auxiliary steering system 12. Thus, the measurement value data recorded by means of the separate additional sensor 30 and provided to the auxiliary steering system 12 is not corrupted by a fault in the electronic steering system 14. Furthermore, thanks to the method 50, a complex estimation method for estimating the steering angle of the wheels 16 of the vehicle 10 can be avoided. The method 50 is therefore particularly compact. Furthermore, by avoiding a complex estimation method, a short control interval can be ensured, so that the reaction time of the auxiliary steering system 12 to a steering input by means of the steering wheel 22 of the vehicle 10 is particularly short. The function of the control device 40 of the auxiliary steering system 12 can optionally be performed by a superordinate drive control device 44 which is arranged in the vehicle 10 in any case, so that the torque control for the wheels 16 provided by the vehicle control device 44 in any case can also be used for the auxiliary steering system 12. The compactness of the method 50 is thus further improved.

[0108] The particular embodiments disclosed herein use a switching circuit (e.g., one or more switching circuits) to implement the standards, protocols, methods, or techniques disclosed herein, functionally couple two or more components, generate information, process information, analyze information, generate signals, encode / decode signals, convert signals, transmit and / or receive signals, control other devices, and / or the like. Any type of circuit can be used.

[0109] In one embodiment, the circuitry comprises one or more data processing apparatus, such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system-on-chip (SoC), and the like, or any combinations thereof, and can include discrete digital or analog circuit elements or electronics, or combinations thereof. In one embodiment, the circuitry comprises a hardware circuit implementation (e.g., an implementation in analog circuitry, an implementation in digital circuitry, etc., and combinations thereof).

[0110] In one embodiment, the switching circuitry comprises a combination of switching circuitry and a computer program product having software or firmware instructions stored on one or more computer-readable memories and that work in conjunction to cause the apparatus to perform one or more of the protocols, methods, or techniques described herein. In one embodiment, the circuitry technology comprises switching circuitry, such as a microprocessor or component of a microprocessor, that requires software, firmware, etc. to operate. In one embodiment, the switching circuitry comprises one or more processors or components thereof and associated software, firmware, hardware, etc.

[0111] In this disclosure, reference can be made to quantities and numbers. Such quantities and numbers should not be considered limiting unless expressly stated, but rather as examples of possible quantities or numbers relevant to the present disclosure. In this regard, in this disclosure, the term “number” can also be used to refer to a quantity or number. In this regard, the term “number” refers to any number greater than one, such as two, three, four, five, etc. The terms “for example,” “approximately,” “near,” and the like mean plus or minus 5% of the specified value.

[0112] While the present disclosure has been illustrated and described with reference to one or more embodiments, those skilled in the art, on reading and understanding this specification and the attached drawings, will be able to make equivalent changes and modifications.

Claims

1. A method (50) for operating a vehicle (10) having an auxiliary steering system (12), wherein the vehicle (10) has one or more drive units (18) and / or deceleration devices (20) associated with respective wheels (16) of the vehicle (10), wherein the method (50) comprises at least the following steps: - detecting a failure of an electronic steering system (14) of the vehicle (10), - activating the auxiliary steering system (12) based on a plurality of the drive units (18) and / or the deceleration devices (20), wherein the auxiliary steering system (12) has a control device (40, 44) which, by means of torque control, effects lateral control of the vehicle (10) by means of different wheel-specific torques of a plurality of the drive units (18) and / or the deceleration devices (20), and - recording at least one steering angle or a corresponding measured variable of the wheels (16) by means of an additional sensor (30) of the auxiliary steering system (12), which is associated with the wheels (16) and forwards the recorded steering angle or the corresponding measured variable to the control device (40, 44) of the auxiliary steering system (12).

2. The method (50) according to claim 1, characterized in that The additional sensor (30) records a relative or absolute angular position of the wheels (16) and forwards it to the control device (40, 44) of the auxiliary steering system (12).

3. The method (50) according to claim 2, characterized in that The control device (40, 44) takes into account a reference angle value of the wheels (16).

4. The method (50) according to one of the preceding claims, characterized in that The electronic steering system (14) of the vehicle (10) comprises a front axle steering system (15A) and a rear axle steering system (15B), wherein the failure of the electronic steering system (14) is detected for the front axle steering system (15A) or the rear axle steering system (15B), wherein the auxiliary steering system (12) is additionally activated based on the one of the front axle steering system (15A) and the rear axle steering system (15B) which has not failed, and wherein the control device (44) effects lateral control of the vehicle (10) based at least also on the one of the front axle steering system (15A) and the rear axle steering system (15B) which has not failed.

5. An auxiliary steering system (12) for a vehicle (10), wherein the vehicle (10) has a plurality of wheels (16) and one or more drive units (18) and / or deceleration devices (20), wherein the drive units (18) and / or the deceleration devices (20) are each associated with at least one wheel (16) and are designed to apply a wheel-specific torque to the at least one wheel (16), wherein the auxiliary steering system (12) comprises a control device (40, 44) and at least one additional sensor (30) which is associated with a wheel (16) and is designed to record an angular position of the wheel (16) or a corresponding measured variable and to forward it to the control device (40, 44) of the auxiliary steering system (12), and wherein the control device (40, 44) is designed to activate the auxiliary steering system (12) in the event of a malfunction of the electronic steering system (14) of the vehicle (10) and to achieve lateral control of the vehicle (10) on the basis of torque control, wherein, By means of torque control, actuation signals can be output to the drive units (18) and / or the deceleration devices (20) such that they output wheel-specific torques to the wheels (16) associated therewith, respectively.

6. The assist steering system (12) according to claim 5, characterized in that The electronic steering system (14) of the vehicle (10) comprises a front axle steering system (15A) and a rear axle steering system (15B), wherein the control device is designed to activate the auxiliary steering system (12) at least on the basis of the one of the front axle steering system (15A) and the rear axle steering system (15B) that has not failed, and to implement lateral control of the vehicle (10) at least on the basis of the one of the front axle steering system (15A) and the rear axle steering system (15B) that has not failed, in the event of a failure of the front axle steering system (15A) or the rear axle steering system (15B).

7. The assist steering system (12) according to claim 5 or 6, characterized in that The additional sensor (30) is designed to record a relative or absolute angular position of the wheel (16).

8. A power assisted steering system (12) according to any one of claims 5 to 7, characterised in that, The additional sensor (30) is designed to be couplable to different supply circuits (46).

9. A power assisted steering system (12) according to any one of claims 5 to 8, characterised in that, The additional sensor (30) has a sensor element (32), a sensor logic circuit (34), a communication interface (38) and a power supply connection (36).

10. The assist steering system (12) according to one of claims 1 to 9, characterized in that The additional sensor (30) is designed as at least one of a pinion sensor coupled to a pinion shaft, a linear sensor coupled to a steering rack (27) of the electronic steering system (14), a rotary sensor coupled to a ball screw nut of the electronic steering system (14).

11. A power assisted steering system (12) according to any one of claims 5 to 10, characterised in that, The additional sensor (30) is couplable to a drive control device (44) of the vehicle (10), wherein the drive control device (44) controls the drive unit (18) and / or the reduction device (20) for driving the vehicle (10).

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