Steering system and method for operating a steering system

Abstract

The invention relates to a steering system (10a; 10b), in particular a steer-by-wire steering system, with a control unit (12a; 12b) comprising at least one feedback actuator (14a; 14b) for generating steering resistance and / or a restoring torque on a steering handle (16a) and at least one feedback control unit (18a; 18b) for controlling the operation of the feedback actuator (14a; 14b), with at least one wheel steering angle actuator (20a; 20b) mechanically separated from the control unit (12a; 12b), which comprises at least one steering actuator (22a; 22b) for changing the steering angle of at least one vehicle wheel (24a) and at least one steering control unit (26a; 26b) for controlling the operation of the steering actuator (22a; 22b), and with a transmission unit (28a; 28b), which connects the control unit (12a; 12b) and the wheel steering angle actuator (20a; 20b) at least by means of communication.It is proposed that the feedback control unit (18a; 18b) is intended to control the steering actuator (22a; 22b) in at least one fault operating state in which a fault and / or a failure of the steering control unit (26a; 26b) occurs.

Description

Prior ArtThe invention is based on a steering system according to the preamble of claim 1.Vehicles with conventional steering systems are known from the prior art, in which a steering handle, for example in the form of a steering wheel, is mechanically fixedly connected via a steering column to a wheel steering angle actuator in the form of a steering gear. In order to provide steering assistance, the wheel steering angle actuator in this case regularly comprises a redundantly constructed steering actuator in the form of a servomotor. In the event of a fault, the driver can also provide a further level of fallback in order to steer the vehicle mechanically.In addition, vehicles with steer-by-wire steering systems are known, which manage without a direct mechanical connection between a steering handle and steered vehicle wheels and in which a steering specification is electrically forwarded. Such a steer-by-wire steering system generally comprises an operating unit with a steering handle and with a feedback actuator as well as at least one wheel steering angle actuator, which is mechanically separated from the operating unit and has a steering actuator for changing a wheel steering angle. Due to the lack of mechanical punch-through, the driver cannot provide an additional fallback level in this case, so that other measures must be taken in the event of a fault.An obvious possibility in this context is to provide a further, additional redundancy, so that altogether at least three separate fallback levels are available. However, such additional redundancy is associated with high costs, so that other solutions are focused.It is therefore known to use a vehicle system deviating from the steering system, such as a drive and / or brake system, for example, as a further fallback level. Such methods are known, for example, from DE 10 2017 221 289 A1 and DE 10 2022 103 808 A1. However, access to other vehicle systems is not always possible or only possible to a limited extent, so that there is fundamentally a need for a solution internal to the steering system.Proceeding from this, the object of the invention is in particular to provide a steering system having improved properties with regard to operational safety. The object is achieved by the features of claims 1, 8 and 9, while advantageous embodiments and further developments of the invention can be found in the dependent claims.Disclosure of the InventionThe invention is based on a steering system having an operating unit which comprises at least one feedback actuator for generating a steering resistance and / or a restoring torque to a steering handle and at least one feedback control unit for controlling an operation of the feedback actuator, having at least one wheel steering angle actuator which is mechanically separate from the operating unit and comprises at least one steering actuator for changing a wheel steering angle of at least one vehicle wheel and at least one steering control unit for controlling an operation of the steering actuator, and having a transmission unit which connects the operating unit and the wheel steering angle actuator to one another at least in a communicating manner.It is proposed that the feedback control unit is provided for controlling the steering actuator in at least one fault operating state in which a fault and / or a failure of the steering control unit occurs, specifically in particular via the transmission unit. The feedback control unit of the operating unit accordingly serves as a backup control for the wheel steering angle actuator, wherein the feedback control unit can be provided, depending on the fault operating state, to replace the steering control unit of the wheel steering angle actuator completely or to cooperate with the steering control unit for controlling the steering actuator. This configuration can in particular increase steering-internal operating safety and at the same time provide an advantageously cost-effective solution.The steering system is provided for use in a vehicle, in particular a motor vehicle, and is in the present case in particular designed as a steer-by-wire steering system, in which a steering specification of a driver is advantageously transmitted purely electrically to the vehicle wheels. In principle, the vehicle can also comprise an automated and / or autonomous driving operating mode in this context. In this context, an "operating unit" is to be understood to mean an input unit that can be actuated by a driver for actuating the at least one wheel steering angle actuator. Furthermore, the operating unit can in particular also comprise the steering handle, which is designed, for example, as a steering wheel. In addition, the operating unit can comprise at least one disconnection switching unit, advantageously in the form of one or more phase disconnection switches, for disconnecting the feedback control unit from the feedback actuator. The feedback actuator is designed in particular as an electric motor and can fundamentally comprise a plurality of mutually independent part machines which are advantageously of structurally identical construction. Furthermore, the feedback control unit can comprise at least one arithmetic logic unit, at least one power electronics unit, for example in the form of a B6 bridge circuit, and at least one driver unit for providing a control voltage and / or a control current for at least one power switch of the power electronics unit. In addition, the feedback control unit can have a plurality of control electronics which are independent of one another and which are advantageously of identical construction and can each comprise a computing logic, a power electronics system and a driver unit. A "wheel steering angle actuator" is to be understood as an actuating unit operatively connected to at least one vehicle wheel, which is provided to transmit a steering specification to the vehicle wheel by changing a wheel steering angle of at least one vehicle wheel and thereby advantageously control at least one orientation of the vehicle wheel and / or influence a direction of travel of the vehicle. For this purpose, the wheel steering angle actuator advantageously comprises at least one steering actuator, for example in the form of a toothed rack, and the steering actuator, which is operatively connected in particular to the steering actuator. Furthermore, the wheel steering angle actuator can comprise at least one further disconnection switching unit, advantageously in the form of one or more phase disconnection switches, for disconnecting the steering control unit from the steering actuator. In addition, the wheel steering angle actuator can be designed in particular as a central actuator and can be assigned to at least two, in particular steerable, vehicle wheels or can be designed as a single wheel actuator and can be assigned exactly to one, in particular steerable, vehicle wheel. The steering actuator is designed in particular as an electric motor and can fundamentally comprise a plurality of further part machines which are independent of one another and which are advantageously of structurally identical construction. Furthermore, the steering control unit can comprise at least one further computing logic, at least one further power electronics, for example in the form of a B6 bridge circuit, and at least one further driver unit for providing a control voltage and / or a control current for at least one further power switch of the further power electronics. In addition, the steering control unit can have a plurality of mutually independent further control electronics which are advantageously of identical construction and can each comprise a further arithmetic logic unit, a further power electronics unit and a further driver unit.Furthermore, a "transmission unit" is to be understood to mean, in particular, an electrical, optical and / or wireless connection for exchanging data and / or information and / or energy between the operating unit and the at least one wheel steering angle actuator. In addition, the transmission unit can provide a direct connection between the operating unit and the at least one wheel steering angle actuator or an indirect connection between the operating unit and the at least one wheel steering angle actuator, for example via a central processing unit. The transmission unit can advantageously be designed as a BUS connection. Particularly advantageously, the transmission unit can comprise a private CAN and / or an interprocessor communication connection between the feedback control unit and the steering control unit. Particularly preferably, the transmission unit is configured such that, in the fault operating state, fault information is transmitted from the wheel steering angle actuator to the operating unit and the feedback control unit can be requested to take over control of the steering actuator or at least one part machine of the steering actuator. Moreover, "a fault and / or a failure of the steering control unit" is to be understood to mean, in particular, a fault and / or an at least partial or complete failure of the steering control unit itself and / or of a peripheral assembly, such as, for example, a power supply, which interacts with the steering control unit, and a fault of the steering control unit which is caused thereby. "Provided" is to be understood in particular as being specially programmed, designed and / or equipped. The fact that an object is provided for a specific function is to be understood in particular to mean that the object fulfills and / or executes this specific function in at least one application state and / or operating state.It is further proposed that the feedback control unit is provided to actuate the feedback actuator with reduced power in the fault operating state or to set an actuation of the feedback actuator. In this way, in particular a high level of operational reliability can be achieved. Furthermore, such a configuration has the advantage that the driver is still able to steer the vehicle in the desired direction, even with reduced feedback or without the feedback from the feedback actuator at the steering handle.It is furthermore proposed that the steering system comprises at least one, in particular additional, switching unit for electrically connecting the feedback control unit to the steering actuator. The switching unit is preferably different from the disconnection switching unit for disconnecting the feedback control unit from the feedback actuator and from the further disconnection switching unit for disconnecting the steering control unit from the steering actuator. Furthermore, the switching unit could in principle be integrated into the wheel steering angle actuator. According to an advantageous embodiment, however, it is proposed that the switching unit is integrated into the operating unit and is arranged in terms of circuitry between power electronics of the feedback control unit and the transmission unit. Preferably, the switching unit establishes an electrical connection between the feedback control unit and the steering actuator via the transmission unit. Particularly preferably, the feedback control unit, in particular the power electronics, is electrically connected directly to the steering actuator via the switching unit and the transmission unit. This allows an advantageous control possibility of the steering actuator to be achieved by means of the feedback control unit.It is furthermore proposed that the wheel steering angle actuator comprises at least one detection sensor system, in particular assigned to the steering actuator, for detecting at least one operating characteristic variable of the steering actuator, wherein the detection sensor system is provided to transmit the operating characteristic variable to the feedback control unit, preferably via the transmission unit, at least in the fault operating state, in particular in sufficient quality, and wherein the feedback control unit is provided to control the steering actuator in the fault operating state as a function of the operating characteristic variable. Particularly advantageously, the operating parameter can be a rotor position signal of the steering actuator. In principle, the operating parameter can also be provided redundantly and / or via two redundant channels. This allows advantageous synchronization to be achieved during the control of the steering actuator by means of the feedback control unit.A particularly non-noticeable emergency operation functionality, which additionally fulfills corresponding safety requirements, can be achieved in particular if the feedback control unit is provided to take over the control of the steering actuator in the fault operating state within a predefined fault tolerance time. In particular, in this case, the feedback control unit, the switching unit, the transmission unit and / or the steering actuator can be designed accordingly in order to enable the steering actuator to be actuated within the predefined fault tolerance time.According to a further embodiment, it is proposed that the steering actuator comprises at least two independent steering sub-machines and the steering control unit comprises at least two independent steering control electronics, wherein one of the steering control electronics is assigned to each steering sub-machine, and wherein the feedback control unit is provided to replace at least one of the steering control electronics or both steering control electronics in the fault operating state. The wheel steering angle controller in this case accordingly provides at least two separate and independent control channels, each control channel being assigned one of the steering submachines and one of the steering control electronics. This allows advantageous redundancy in the wheel steering angle actuator to be achieved, as a result of which operational reliability can be further improved.It is also proposed that the feedback actuator comprises at least two independent feedback submachines and the feedback control unit comprises at least two independent feedback control electronics, wherein one of the feedback control electronics is assigned to each feedback submachine, and wherein at least one of the feedback control electronics is provided to replace at least part of the steering control unit or the entire steering control unit in the fault operating state. In this case, the control unit accordingly provides at least two separate and independent control channels, each control channel being assigned one of the feedback submachines and one of the feedback control electronics. This allows advantageous redundancy to be achieved in the operating unit, as a result of which operating reliability can be further improved.Preferably, furthermore, first feedback control electronics are assigned to first steering control electronics and are provided to replace the first steering control electronics in a first fault operating state, namely in the event of a fault and / or a failure of the first steering control electronics, and to take over control of a first steering submachine of the steering actuator, while second feedback control electronics are assigned to second steering control electronics and are provided to replace the second steering control electronics in a second fault operating state, namely in the event of a fault and / or a failure of the second steering control electronics, and to take over control of a second steering submachine of the steering actuator. For this purpose, the first feedback control electronics can be connected to the first steering control electronics via a first interprocessor communication connection and the second feedback control electronics can be connected to the second steering control electronics via a second interprocessor communication connection. In this case, the feedback control unit can thus be provided to cooperate with the steering control unit for controlling the steering actuator and to partially replace the steering control unit. The first feedback control electronics and the second feedback control electronics are particularly advantageously also provided for replacing the first steering control electronics and the second steering control electronics in a third fault operating state, namely in the event of a fault and / or a failure of the first steering control electronics and the second steering control electronics, and for assuming control of the first steering submachine and the second steering submachine of the steering actuator. In this case, the feedback control unit is thus provided to replace the steering control unit completely.In addition, a method for operating the aforementioned steering system is proposed, wherein in at least one fault operating state, in which a fault and / or a failure of the steering control unit is determined, the feedback control unit is used to actuate the steering actuator. In addition, in particular via the transmission unit, operation of the wheel steering angle actuator can be monitored. In this way, in particular the advantages already mentioned above can be achieved. In particular, an internal steering operating safety can be increased and at the same time an advantageously cost-effective solution can be provided.The steering system and the method for operating the steering system are not intended to be limited to the application and embodiment described above. In particular, the steering system and the method for operating the steering system to fulfil a functionality described herein can have a number that differs from a number of individual elements, components and units mentioned herein.DRAWINGSFurther advantages are evident from the following description of the drawings. Several exemplary embodiments of the invention are shown in the drawings.The following are shown: FIGS. 1 a- b show a vehicle with a steering system designed as a steer-by-wire steering system in a simplified illustration, FIG. 2 shows a simplified schematic diagram of a structure of the steering system, FIG. 3 shows an exemplary flow chart with main method steps of a method for operating the steering system, and FIG. 4 shows a further exemplary embodiment of a steering system in a more detailed illustration.DESCRIPTION OF THE EMBODIMENTSFIGS. 1 aand 1 b show a vehicle 44 a, which is designed as an example as a passenger motor vehicle and has a plurality of vehicle wheels 24 aand a steering system 10 ain a simplified illustration. The steering system 10 acomprises an operative connection with the vehicle wheels 24 aand is provided for influencing a direction of travel of the vehicle 44 a. Furthermore, the steering system 10 ais in the present case designed as a steer-by-wire steering system, in which a steering specification is electrically forwarded to the vehicle wheels 24 ain at least one operating state.The steering system 10 acomprises an operating unit 12 a, which can be actuated in particular by a driver and / or occupant. The operating unit 12 aincludes a steering handle 16 a, for example in the form of a steering wheel, and a feedback actuator 14 a, in particular mechanically coupled to the steering handle 16 a. In the present case, the feedback actuator 14 ais provided at least in a normal operating state for providing a feedback torque and thereby for generating a steering feel, in particular in the form of a steering resistance and / or a restoring torque, on the steering handle 16 a. For this purpose, the feedback actuator 14 aincludes at least one electric motor (not explicitly shown), in particular designed as a permanently excited synchronous motor. Furthermore, the operating unit 12 aincludes a feedback control unit 18 aconnected electrically to the feedback actuator 14 afor controlling an operation of the feedback actuator 14 a. A configuration of the feedback control unit 18 ais described below with reference to FIG. 2. Alternatively, a steering handle could also be designed as a joystick, as a steering lever and / or as a steering ball or the like. Further, a feedback actuator could include multiple electric motors.In addition, the steering system 10 aincludes a wheel steering angle actuator 20 a, which is known per se. The wheel steering angle actuator 20 ais formed mechanically separately from the operating unit 12 a. The wheel steering angle actuator 20 ais connected purely electrically to the operating unit 12 a. Furthermore, the wheel steering angle actuator 20 ais designed as a central actuator, for example. The wheel steering angle actuator 20 acomprises an operative connection with at least two of the vehicle wheels 24 a, in particular two front wheels, and is provided for converting the steering specification into a steering movement of the vehicle wheels 24 a. For this purpose, the wheel steering angle actuator 20 aincludes a steering actuator 46 a, which is designed as a rack by way of example, and a steering actuator 22 acooperating with the steering actuator 46 a. The steering actuator 22 acomprises at least one further electric motor (not explicitly shown), in particular configured as a permanently excited synchronous motor, and is provided for providing a steering torque for adjusting the steerable vehicle wheels 24 a. Furthermore, the wheel steering angle actuator 20 aincludes a steering control unit 26 aconnected electrically to the steering actuator 22 afor controlling an operation of the steering actuator 22 a. A configuration of the steering control unit 22 ais described below with reference to FIG. 2. In principle, a steering system could also comprise a plurality of wheel steering angle actuators, in particular designed as an individual wheel actuator, wherein in this case each wheel steering angle actuator can have a steering actuator and a steering control unit. Furthermore, a steering actuator could comprise a plurality of electric motors or actuators deviating from a permanently excited synchronous motor.Furthermore, the steering system 10 acomprises a transmission unit 28 awhich connects the operating unit 12 aand the wheel steering angle actuator 20 ato one another in an at least communicating manner. The transmission unit 28 ais provided for exchanging data and / or information between the operating unit 12 aand the wheel steering angle actuator 20 a. In addition, in the present case, the transmission unit 28 ais provided for the transmission of energy between the operating unit 12 aand the wheel steering angle actuator 20 a. In the present case, the transmission unit 28 ais designed as an electrical connecting line, in particular as a BUS connection. In addition, in the present case, the transmission unit 28 aincludes, by way of example, a private CAN and an interprocessor communication connection between the feedback control unit 18 aand the steering control unit 26 a.FIG. 2 shows a basic internal structure of the operating unit 12 aand of the wheel steering angle actuator 20 a.The feedback control unit 18 aincludes a power path 48 awith power electronics 32 a. The power electronics 32 ais designed as an output stage, for example as a B6 bridge circuit, and on the one hand has an electrical connection to a power supply (not shown), for example a vehicle battery, and on the other hand has an electrical connection to the feedback actuator 14 a. The power electronics 32 ahere are used to supply the feedback actuator 14 a. In principle, a vehicle can of course also have a plurality of energy supply networks, which can also be of redundant design.In addition, the feedback control unit 18 aincludes a control path 50 awith a computing logic 52 aand a driver unit 54 a. The computing logic 52 acan comprise at least one processor, for example. The driver unit 54 acan be designed, for example, as a half-bridge driver and / or gate driver. The driver unit 54a has, on the one hand, an electrical connection to the computing logic 52a and, on the other hand, an electrical connection to the power electronics 32a. The driver unit 54 ais provided to drive at least one power switch (not shown) and advantageously all power switches of the power electronics 32 aand to provide a control voltage and / or a control current for the at least one power switch. In principle, an operating unit can of course also comprise a plurality of computing logics, power electronics and / or driver units. In addition, corresponding power electronics can have different power switches, such as phase separators and / or rail switches and / or short-circuit switches.Furthermore, the operating unit 12 aincludes at least one detection sensor system 56 aassociated with the feedback actuator 14 afor detecting at least one operating characteristic variable of the feedback actuator 14 aand preferably a plurality of operating characteristics of the feedback actuator 14 a. The detection sensor system 56 acan be designed, for example, as a rotor position sensor and can be provided for detecting a rotor position signal of the feedback actuator 14 a. The detection sensor system 56 acomprises an electrical connection to the feedback control unit 18 a, in particular to the computing logic unit 52 a. In the present case, the feedback control unit 18 ais provided to actuate the feedback actuator 14 ain a normal operating state as a function of the operating characteristic variable of the feedback actuator 14 a.The steering control unit 26 aincludes a further power path 58 awith a further power electronics 60 a. The further power electronics 60 ais designed as an output stage, for example as a B6 bridge circuit, and on the one hand has an electrical connection to a further energy supply (not shown), for example a vehicle battery, and on the other hand has an electrical connection to the steering actuator 22 a. The further power electronics 60 ahere are used to supply the steering actuator 22 a. In principle, a vehicle can of course also have a plurality of further energy supply networks, which can additionally be of redundant design.In addition, the steering control unit 26 aincludes a further control path 62 awith a further arithmetic logic 64 aand a further driver unit 66 a. The further computing logic 64 acan comprise at least one further processor, for example. The further driver unit 66 acan be designed, for example, as a half-bridge driver and / or gate driver. The further driver unit 66 acomprises on the one hand an electrical connection to the further computing logic 64 aand on the other hand an electrical connection to the further power electronics 60 a. The further driver unit 66 ais provided to actuate at least one further power switch (not shown) and advantageously all further power switches of the further power electronics 60 aand to provide a control voltage and / or a control current for the at least one further power switch. In principle, a wheel steering angle actuator can of course also comprise a plurality of computing logics, power electronics and / or driver units.Furthermore, the wheel steering angle actuator 20 aincludes at least one further detection sensor system 34 aassociated with the steering actuator 22 afor detecting at least one operating characteristic variable of the steering actuator 22 a. The further detection sensor system 34 acan be designed, for example, as a rotor position sensor and can be provided for detecting a rotor position signal of the steering actuator 22 a. The further detection sensor system 34 acomprises at least one electrical connection to the steering control unit 26 a, in particular to the further computing logic 64 a. In principle, however, an interprocessor communication link could also be used between a further detection sensor system and a steering control unit. In addition, the further detection sensor system 34 ain the present case has an electrical connection to the feedback control unit 18 a, in particular to the computing logic unit 52 a. In the present case, the steering control unit 26 ais provided to actuate the steering actuator 22 ain a normal operating state as a function of the operating characteristic variable of the steering actuator 22 a.Due to the lack of mechanical reach-through between the operating unit 12 aand the wheel steering angle actuator 20 a, the driver cannot provide an additional fall-back plane, so that in a fault operating state in which a fault and / or a failure of the steering control unit 26 aoccurs, other measures must be taken.In the present case, an in-steering approach for increasing operating safety is followed. In the present case, the feedback control unit 18 ais provided for controlling the steering actuator 22 ain at least one fault operating state in which a fault and / or a failure of the steering control unit 26 aoccurs. In this case, the feedback control unit 18 ais provided to take over the control of the steering actuator 22 awithin a predefined fault tolerance time. The feedback control unit 18 atherefore serves as a backup control for the wheel steering angle actuator 20 a. Furthermore, the transmission unit 28 ais configured such that, in the fault operating state, fault information is transmitted from the wheel steering angle actuator 20 ato the operating unit 12 aand the feedback control unit 18 acan be requested in order to take over control of the steering actuator 22 a. According to the present exemplary embodiment, the feedback control unit 18 ais provided here to replace the steering control unit 26 ain the fault operating state completely and to set a control of the feedback actuator 14 a. Alternatively, however, actuation with reduced power is also possible.For this purpose, the steering system 10 aincludes a switching unit 30 a, in particular an additional switching unit, for electrically connecting the feedback control unit 18 ato the steering actuator 22 a. The switching unit 30 ais here integrated into the operating unit 12 aand is arranged in terms of circuitry between the power electronics 32 aand the transmission unit 28 a. The switching unit 30 ais provided to establish an electrical connection between the feedback control unit 18 aand the steering actuator 22 avia the transmission unit 28 a.Furthermore, the detection sensor system 34 ais provided to provide the operating characteristic variable of the steering actuator 22 avia the transmission unit 28 ato the feedback control unit 18 a, while the feedback control unit 18 ais provided to use this operating characteristic variable in the fault operating state in the actuation of the steering actuator 22 aand / or to take it into account.This configuration enables high operational safety to be achieved, wherein the driver is still able to steer the vehicle 44 ain the desired direction, even without the feedback from the feedback actuator 14 aon the steering handle 16 a.FIG. 3 finally shows an exemplary flow diagram with main method steps of a method for operating the steering system 10 a.A method step 70 acorresponds to an in particular error-free normal operating state. In this case, the feedback actuator 14 aof the operating unit 12 ais controlled via the feedback control unit 18 aof the operating unit 12 ato generate a steering resistance and / or a restoring torque on the steering handle 16 a. In addition, the steering actuator 22 aof the wheel steering angle actuator 20 ais controlled via the steering control unit 26 aof the wheel steering angle actuator 20 ato set a wheel steering angle of the vehicle wheels 24 a, for example as a function of a steering specification at the steering handle 16 a.In a method step 72 a, a fault and / or a failure of the steering control unit 26 a, and consequently a fault operating state, occurs. On account of the fault operating state, fault information is transmitted from the wheel steering angle actuator 20 ato the operating unit 12 avia the transmission unit 28 aand the feedback control unit 18 ais requested in order to take over control of the steering actuator 22 a.Subsequently, in a method step 74 a, the switching unit 30 ais controlled in such a way that the feedback control unit 18 ais disconnected from the feedback actuator 14 aand connected to the steering actuator 22 a. In principle, two separate switching units could also be used for this purpose. In principle, a disconnection switching unit (not shown) of the wheel steering angle actuator 20 acan also be controlled analogously in order to disconnect the steering control unit 26 afrom the steering actuator 22 a.In a method step 76 a, the steering actuator 22 aof the wheel steering angle actuator 20 ais then controlled via the feedback control unit 18 aof the operating unit 12 a, in particular in order to set the wheel steering angle of the vehicle wheels 24 a, for example as a function of a steering specification at the steering handle 16 a. The takeover by the feedback control unit 18 apreferably takes place within a predefined fault tolerance time. The feedback control unit 18 aof the operating unit 12 atherefore serves as a backup control for the wheel steering angle actuator 20 ain the fault operating state.The exemplary flowchart in FIG. 3 is intended to describe, merely by way of example, a method for operating the steering system 10 a. In particular, individual method steps can also vary or add additional method steps. In this context, it is conceivable, for example, to use a feedback control unit in a fault operating state for controlling a feedback actuator and for controlling a steering actuator.In FIG. 4 a further embodiment of the invention is shown. The following description and the drawing are limited substantially to the differences between the exemplary embodiments, wherein with regard to identically denoted components, in particular with regard to components with the same reference numerals, reference can in principle also be made to the drawings and / or the description of the other exemplary embodiment, in particular of FIGS. 1 to 3. To distinguish between the exemplary embodiments, the letter a is appended to the reference numerals of the exemplary embodiment in FIGS. 1 to 3. In the exemplary embodiment of FIG. 4, the letter a is replaced by the letter b.The further exemplary embodiment of FIG. 4 differs from the previous exemplary embodiment at least substantially in terms of a configuration of a feedback actuator 14 band a feedback control unit 18 bof an operating unit 12 band of a steering actuator 22 band of a steering control unit 26 bof a wheel steering angle actuator 20 b.In the present case, both the operating unit 12 band the wheel steering angle actuator 20 bprovide two separate and independent control channels.Accordingly, the feedback actuator 14b comprises two feedback submachines 40b, 40b' which are independent of one another, and the feedback control unit 18b comprises two feedback control electronics 42b, 42b' which are independent of one another, wherein one of the feedback control electronics 42b, 42b' is assigned to each feedback submachine 40b, 40b'. In addition, each control channel of the operating unit 12b can comprise a disconnection switching unit 68b, 68b', advantageously in the form of one or more phase disconnection switches, for disconnecting the respective feedback control electronics 42b, 42b' from the respective feedback submachine 40b, 40b'. The feedback submachines 40b, 40b' and the feedback control electronics 42b, 42b' can be constructed identically. In addition, the feedback control electronics 42b, 42b' each have a computing logic 52b, 52b', a power electronics 32b, 32b' and a driver unit 54b, 54b'. Furthermore, the operating unit 12b comprises a detection sensor system 56b assigned to the feedback actuator 14b for detecting operating characteristics of the two feedback submachines 40b, 40b'.In addition, the steering actuator 22b comprises two independent steering sub-machines 36b, 36b' and the steering control unit 26b comprises two independent steering control electronics 38b, 38b', wherein one of the steering control electronics 38b, 38b' is associated with each steering sub-machine 36b, 36b'. In addition, each control channel of the wheel steering angle actuator 20 bmay comprise a further isolating switch unit 69 b, 69 b', advantageously in the form of one or more phase isolating switches, for isolating the respective steering control electronics 38 b, 38 b' from the respective steering submachine 36 b, 36 b'. The steering submachines 36b, 36b' and the steering control electronics 38b, 38b' are constructed identically. In addition, the steering control electronics 38b, 38b' each have a further arithmetic logic unit 64b, 64b', a further power electronics unit 60b, 60b' and a further driver unit 66b, 66b'. Furthermore, the wheel steering angle actuator 20b comprises a further detection sensor system 34b assigned to the steering actuator 22b for detecting operating characteristics of the two steering submachines 36b, 36b'.In addition, each control channel of the control unit 12b in the present case comprises an additional switching unit 30b, 30b' for electrically connecting the respective feedback control electronics 42b, 42b' to one of the steering sub-machines 36b, 36b'. The electrical connection is in turn effected via a transmission unit 28 bbetween the operating unit 12 band the wheel steering angle actuator 20 b.In this case, first feedback control electronics 42b are assigned to first steering control electronics 38b and are provided to replace first steering control electronics 38b in a first fault operating state, namely in the event of a fault and / or a failure of first steering control electronics 38b, and to take over control of a first steering sub-machine 36b of steering actuator 22b, while second feedback control electronics 42b' are assigned to second steering control electronics 38b' and are provided to replace second steering control electronics 38b' in a second fault operating state, namely in the event of a fault and / or a failure of second steering control electronics 38b', and to take over control of a second steering sub-machine 36b' of steering actuator 22b. In the first fault operating state and in the second fault operating state, the feedback control unit 18 bis thus provided to cooperate with the steering control unit 26 bto actuate the steering actuator 22 band to partially replace the steering control unit 26 b, and therefore the first steering control electronics 38 bor the second steering control electronics 38 b'. At the same time, in these cases, the feedback control unit 18 bmay be provided to actuate the feedback actuator 14 b, more precisely one of the feedback submachines 40 b, 40 b', with reduced power.In addition, the first feedback control electronics 42b and the second feedback control electronics 42b' are provided to replace the first steering control electronics 38b and the second steering control electronics 38b' in a third fault operating state, namely in the event of a fault and / or failure of the first steering control electronics 38b and the second steering control electronics 38b', and to take over a control of the first steering submachine 36b and the second steering submachine 36b' of the steering actuator 22b. In the third fault operating state, the feedback control unit 18 bis thus provided to replace the steering control unit 26 bin its entirety, and therefore the first steering control electronics 38 band the second steering control electronics 38 b'. In addition, the feedback control unit 18 bin this case is provided to set a control of the feedback actuator 14 b.In FIG. 4, the first fault operating state is also shown by way of example (indicated by dashed lines and components). In this case, the first feedback control electronics 42 bis provided to replace the first steering control electronics 38 band to take over a control of the first steering submachine 36 bof the steering actuator 22 b. At the same time, the first feedback control electronics 42 bis provided for setting a control of the first feedback submachine 40 bin the fault operating state. The second feedback control electronics 42b', on the other hand, are also provided for controlling the second feedback submachine 40b', so that the feedback actuator 14b is controlled with reduced power in this case. In addition, the second steering control electronics 38b' are also provided for controlling the second steering submachine 36b', so that the first feedback control electronics 42b and the second steering control electronics 38b' cooperate in this case for controlling the steering actuator 22b.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2017 221 289 A1

[0005] DE 10 2022 103 808 A1

[0005]

Claims

Steering system (10a; 10b), in particular steer-by-wire steering system, having an operating unit (12a; 12b) which comprises at least one feedback actuator (14a; 14b) for generating a steering resistance and / or a restoring torque to a steering handle (16a) and at least one feedback control unit (18a; 18b) for controlling an operation of the feedback actuator (14a; 14b), having at least one wheel steering angle actuator (20a; 20b) which is mechanically separate from the operating unit (12a; 12b) and which comprises at least one steering actuator (22a; 22b) for changing a wheel steering angle of at least one vehicle wheel (24a) and at least one steering control unit (26a; 26b) for controlling an operation of the steering actuator (22a; 22 b), and having a transmission unit (28 a; 28 b) which connects the operating unit (12 a; 12 b) and the wheel steering angle actuator (20 a; 20 b) to one another in at least communicating fashion, characterized in that the feedback control unit (18 a; 18 b) is provided for actuating the steering actuator (22 a; 22 b) in at least one fault operating state in which a fault and / or a failure of the steering control unit (26 a; 26 b) occurs.Steering system (10a; 10b) according to Claim 1, characterized in that the feedback control unit (18a; 18b) is provided for the purpose of actuating the feedback actuator (14a; 14b) in the fault operating state with reduced power or of setting an actuation of the feedback actuator (14a; 14b).Steering system (10a; 10b) according to Claim 1 or 2, characterized byat least one switching unit (30a; 30b, 30b') for electrically connecting the feedback control unit (18a; 18b) to the steering actuator (22a; 22b), wherein the switching unit (30a; 30b, 30b') is integrated into the operating unit (12a; 12b) and is arranged in terms of circuitry between power electronics (32a; 32b, 32b') of the feedback control unit (18a; 18b) and the transmission unit (28a; 28b).Steering system (10a; 10b) according to one of the preceding claims, characterized in that the wheel steering angle actuator (20a; 20b) comprises at least one detection sensor system (34a; 34b) for detecting at least one operating characteristic variable of the steering actuator (22a; 22b), wherein the detection sensor system (34a; 34b) is provided to transmit the operating characteristic variable to the feedback control unit (18a; 18b) at least in the fault operating state, and wherein the feedback control unit (18a; 18b) is provided to actuate the steering actuator (22a; 22b) in the fault operating state as a function of the operating characteristic variable.Steering system (10a; 10b) according to one of the preceding claims, characterized in that the feedback control unit (18a; 18b) is provided to take over the control of the steering actuator (22a; 22b) in the fault operating state within a predefined fault tolerance time.Steering system (10b) according to one of the preceding claims, characterized in that the steering actuator (22b) comprises at least two independent steering sub-machines (36b, 36b') and the steering control unit (26b) comprises at least two independent steering control electronics (38b, 38b'), wherein each steering sub-machine (36b, 36b') is assigned one of the steering control electronics (38b, 38b'), and wherein the feedback control unit (18b) is provided to replace at least one of the steering control electronics (38b, 38b') or both steering control electronics (38b, 38b') in the fault operating state.Steering system (10b) according to one of the preceding claims, characterized in that the feedback actuator (14b) comprises at least two feedback sub-machines (40b, 40b') independent of one another and the feedback control unit (18b) comprises at least two feedback control electronics (42b, 42b') independent of one another, wherein one of the feedback control electronics (42b, 42b') is assigned to each feedback sub-machine (40b, 40b'), and wherein at least one of the feedback control electronics (42b, 42b') is provided for replacing at least part of the steering control unit (26b) or the entire steering control unit (26b) in the fault operating state.Vehicle (44a), in particular motor vehicle, having a steering system (10a; 10b) according to one of the preceding claims.Method for operating a steering system (10a; 10b) according to one of Claims 1 to 7, wherein, in at least one fault operating state in which a fault and / or a failure of the steering control unit (26a; 26b) is determined, the feedback control unit (18a; 18b) is used to actuate the steering actuator (22a; 22b).

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