Steering input device for specifying a steering movement according to the steer-by-wire concept and method for operating a steering input device

Abstract

The invention relates to a steering input device (300) for specifying a steering movement according to the steer-by-wire concept, comprising a moveable steering unit (301) and a drive device (302) for generating a torque acting on the steering unit (301). A failure protection system (305) functions such that, in the event of a failure of the drive device (302), the steering unit (301) is neither blocked nor can it be moved without resistance. The failure protection system (305) comprises a braking device (1) that is independent of the drive device (302), with a maximum braking torque that is less than a maximum torque of the drive device (302). The failure protection system (305) is designed and suited to actuate the braking device (1) in the event of a failure of the drive device (302), and to thereby brake the movement of the steering unit (301) with a targeted braking torque, i.e. failure braking torque.

Description

[0001] Steering presetting device for specifying a steering movement according to the

[0002] Steer-by-wire concept and method for operating a

[0003] Steering control device

[0004] The invention relates to a steering control device for specifying a steering movement according to the steer-by-wire concept. The steering control device comprises at least one movable steering unit and at least one drive device for generating a torque acting on the steering unit.

[0005] Such steering control systems are subject to stringent requirements. For example, precise steering feedback and a smooth, jerk-free steering response, especially around the center position, as well as overall smooth, harmonious steering behavior are required. Furthermore, the steering system must be able to provide high torques or counteract the manual steering movement (the torque then corresponds to a braking torque). This is useful, for example, for representing end stops, for supporting the driver when exiting the vehicle, or as a counter-torque during very rapid twisting or steering movements.

[0006] Therefore, steering systems with an electric motor have become popular. This motor is coupled to the steering wheel either directly or via a reduction gear or (toothed) belt. Such directly mounted electric motors generate, for example, active braking torques (nominal torques) of up to eight newton meters (Nm) and short-term passive braking torques of up to 25 Nm.

[0007] A steer-by-wire steering system for a motor vehicle with a three-phase synchronous motor as a direct drive for actively moving the steering wheel and with a magnetorheological brake is known from DE 10 221 241 A1. The stator of the synchronous motor is mounted on a dashboard. The rotor is connected in a rotationally fixed manner to an actuating shaft (steering shaft) via a hollow shaft. The actuating shaft is rotationally connected to the steering wheel. The magnetorheological brake comprises a ring magnet and a brake disc, as well as a gap arranged between them for the magnetorheological fluid. The ring magnet is attached to the stator side. The brake disc is rotationally mounted on the actuating shaft. The direct drive serves to return the steering wheel after cornering. The magnetorheological braking device is provided to apply an active countertorque to a steering movement exerted by the driver.This should have low power consumption and be able to provide a very high counter torque without excessive heating.

[0008] Another requirement for steering control systems concerns safety in the event of a malfunction, such as a power outage or a failure of the components that generate the torque (failsafe). Because there is no longer any torque opposing the steering movement, the steering is very easy, and no resistance is felt when turning.

[0009] For example, if an electric motor suddenly fails when turning into a bend, the torque in the steering system counteracting the manual steering movement drops abruptly. This can lead to an unintentional sharp steering angle being applied via the steering wheel (oversteering). This results in a very dangerous driving situation that must be corrected by the driver. This can even lead to a loss of control of the vehicle if the driver, for example, oversteers into the oncoming lane or over the edge of the road on a winding uphill stretch. The known steering systems that can compensate for such errors (redundant design) are generally very complex, space-consuming and very expensive.

[0010] If the steering unit is designed to be mechanically stiff (= high base torque), haptically perfect controllability during normal operation (active return, etc.) is no longer possible. Only very smooth steering units (preferably < 0.1 Nm base torque for all steer-by-wire steering components) enable haptically sophisticated and harmonious steering movements.

[0011] EP 3 676 156 B1 discloses a steer-by-wire steering system with an electric motor for generating an active torque acting on the steering unit. A magnetorheological fluid and an electric coil are accommodated in a bearing housing for a bearing on the motor shaft of the electric motor. By generating a magnetic field using the coil, the magnetorheological fluid solidifies, requiring a higher torque to rotate the motor shaft. This can generate a passive torque or braking torque that acts on the steering unit. The braking torque can be so high that end stops (end position lock) can be generated for the rotation of the steering unit. In addition, the bearing can also brake if the electric motor fails. The coil is supplied with power to generate the magnetic field.When the power source is switched off, the bearing can only generate a very small resistance to the mobility of the motor shaft.

[0012] In contrast, the object of the present invention is to provide an improved steering control device. In particular, the steering control device should offer a high level of safety even in the event of a malfunction and, at the same time, be easy to implement and economically manufacture in terms of design and space requirements.

[0013] This object is achieved by a steering input device with the features of claim 1. The method according to the invention is the subject matter of claim 24. Preferred developments of the invention are the subject matter of the dependent claims. Further advantages and features of the present invention emerge from the general description and from the description of the exemplary embodiments. The steering input device according to the invention serves to specify a steering movement according to the steer-by-wire concept. The steering input device can be used, for example, to steer a vehicle or to control a simulator device or a computer simulation (e.g. gaming). The steering input device comprises at least one movable steering unit and at least one drive device for generating a torque acting on the steering unit. The steering input device comprises at least one fault protection device.The purpose of the accident prevention device is to ensure that in the event of a malfunction the drive device is neither blocked nor can be moved without resistance. The accident prevention device comprises at least one braking device which is independent of the drive device. The maximum braking torque of the braking device is less than (or equal to) a maximum torque of the drive device. The accident prevention device is suitable and designed to actuate the braking device in the event of a malfunction of the drive device and in this way (by means of the braking device) to brake the mobility of the steering unit with a targeted braking torque (hereinafter referred to as the accident braking torque).

[0014] The present invention offers many advantages. A significant advantage is the failure protection with its braking device independent of the drive device. The inventive design of the maximum braking torque of the braking device is particularly advantageous. This enables very reliable and, at the same time, particularly inexpensive protection in the event of a failure. The limited braking torque counteracts the risk of the braking device itself becoming a critical source of error in the event of a failure of the drive device, for example, blocking the mobility (twisting) of the steering unit or braking too harshly.

[0015] The steering unit is, in particular, a steering wheel. The steering unit can alternatively be designed as a steering wheel, yoke, handlebar, joystick, control lever, control horn, control pedal, control lever, or as a joystick, or even as a control wheel. Other designs of movable steering units for steering vehicles are also possible. The movement of the steering unit is, in particular, a rotary movement. In particular, the steering unit is movable in at least two directions of rotation and is preferably rotatable. However, pivoting or the like is also possible.

[0016] The steering preset device can be used in motor vehicles (e.g. cars, trucks, on-highway vehicles), aircraft, airplanes (including drones), ships, boats, in agricultural and forestry technology, for example with tractors or combine harvesters, harvesting machines and other field machinery (off-highway vehicles). It can also be used in construction or moving work machines and, for example, forklifts or similar machines, or in simulators for simulating vehicle control (gaming, sim racing, computer peripherals, etc.). The steering preset device can also be used in particular for at least partially or fully autonomous vehicles.

[0017] Particularly preferably, the maximum braking torque of the braking device is less than 6 Nm. Preferably, the maximum braking torque is between 0.1 Nm and 6 Nm. In particular, the maximum braking torque is less than 4 Nm and preferably less than 3.8 Nm. In particular, the maximum braking torque is between 1 Nm and 6 Nm and preferably between 1.5 Nm and 3.8 Nm. It is preferred and advantageous for the maximum braking torque to be a maximum of 3.8 Nm and preferably a maximum of 3.6 Nm and particularly preferably a maximum of 3.5 Nm. Such designs of the maximum braking torque allow noticeable resistance in the event of a malfunction while still enabling smooth movement for safe steering.

[0018] In particular, the maximum braking torque and the emergency braking torque are matched to the size of the steering unit (in particular the diameter of the steering wheel and / or steering wheel and / or the handlebar span). Depending on the steering wheel diameter, the necessary or maximum braking torques can vary, depending on which feel good to the user or are acceptable from a safety perspective. Larger steering wheel diameters require higher braking torques. The tangential forces of the operator (operating forces) on the diameter of the steering device (point of action on the steering wheel rim) are decisive here. With a braking torque of 3.5 Nm and a steering command device diameter of 330 mm, this results in tangential forces (which counteract the user's operating forces) of approximately 21 N. Steering command devices in cars usually have a steering wheel diameter in this range (300 to 400 mm). Trucks usually have a steering wheel diameter between 400 and 500 mm, which means that higher braking torques are permissible or required.are haptically possible (e.g. tangential / operating force = 21 N; steering wheel diameter = 500 mm. This means that approximately 5.25 Nm is possible as the maximum braking torque).

[0019] Advantageously, a maximum tangential force caused by the braking device on the steering control device (and in particular on the steering unit) which counteracts an operating force of a user at an application point of the steering unit is less than 30 N and preferably a maximum of 20 N. The maximum tangential force corresponds to the maximum braking torque multiplied by a distance (of the application point) from a rotational axis of the steering unit.

[0020] It is also possible that the maximum braking torque of the braking device corresponds to only a fraction of the maximum torque that can be provided by the drive device. In particular, the maximum braking torque is less than half, preferably less than one-third, and particularly preferably less than one-quarter of the maximum torque of the drive device. The maximum braking torque can also be less than one-fifth, one-sixth, or one-eighth of the maximum torque of the drive device.

[0021] Preferably, the maximum braking torque corresponds to the emergency braking torque. In other words, the emergency braking torque is equal to the maximum braking torque. In particular, the maximum braking torque corresponds to the emergency braking torque, so that the mobility of the steering unit is braked or can be braked by the braking device in the event of a failure of the drive device (preferably exclusively) with the maximum braking torque. This enables particularly inexpensive and at the same time very reliable emergency protection. The emergency braking torque can also be designed to be lower than the maximum braking torque.

[0022] Preferably, for technical reasons, the braking device cannot apply a braking torque higher than the emergency braking torque and / or the maximum braking torque. In particular, the maximum braking torque corresponds to the emergency braking torque. This offers the advantage that even if the braking device is not functioning properly, excessive braking or even locking of the steering unit cannot occur.

[0023] In particular, this means that the maximum braking torque cannot be exceeded even in the event of a fault in the braking device. In particular, the braking device is designed in such a way that the mobility of the steering unit cannot be braked more than the maximum braking torque. In particular, the braking device cannot block the mobility of the steering unit. In particular, the braking device is designed in such a way that it cannot set a braking torque higher than the maximum braking torque, even in the event of a faulty or incorrect control. For this purpose, the brake is designed, for example, as described in more detail below (for example, magnetic saturation of the magnetic circuit is provided). By adapting the design of the braking device with regard to the maximum braking torque, country-specific or regionally different requirements and specifications can be taken into account.

[0024] The braking device preferably has a fixed, predetermined emergency braking torque. In particular, the emergency braking torque is predetermined for technical or design reasons. In particular, the emergency braking torque is constant. In particular, the emergency braking torque is not adjustable. In other words, in the event of an emergency, the braking device always brakes with a fixed, predetermined and, in particular, constant braking torque. As a result, even if control of the braking device fails, a suitable emergency braking torque for braking the steering unit can still be provided. In such embodiments, the emergency braking torque corresponds, in particular, to the maximum braking torque or is lower.

[0025] It is also possible and advantageous for the braking device to be designed so that the emergency braking torque can be adjusted. However, even then, for technical reasons, it is preferable that the emergency braking torque cannot be set higher than the maximum braking torque.

[0026] In a preferred and advantageous embodiment it is provided that the mobility of the steering unit can be braked by means of the braking device either only with the emergency braking torque or not at all. This also offers a particularly reliable and at the same time inexpensive emergency protection system. In particular the braking device can only apply the emergency braking torque in a braked switching state. If the braking device does not brake the mobility of the steering unit at all, there is in particular only a basic torque of the braking device and in particular no active braking torque. In this case it is very important that the basic torque of the braking device is as low as possible so that sensitive steering is possible in normal operation and the controllability of the drive device can function well (open / closed loop systems). Basic torques of < 0.1 Nm, preferably < 0.05 Nm and particularly preferably < 0.02 Nm are ideal.The basic torque of the braking device could also be referred to as the idle torque of the braking device in an unbraked switching state of the braking device.

[0027] If the emergency protection system activates the braking system in the event of a malfunction, the braking system preferably brakes the mobility of the steering unit exclusively with the malfunction braking torque. However, it is also possible for the braking system to apply different braking torques in the event of a malfunction. For example, the braking torques can be adjusted depending on the malfunction and / or the steering conditions required for the current driving situation.

[0028] Preferably, the mobility of the steering unit can only be braked by means of the braking device in the event of a malfunction. Preferably, the mobility of the steering unit cannot be braked by means of the braking device during normal operation. This enables a particularly high degree of safety and a very robust and, at the same time, cost-effective implementation of the malfunction protection device. In particular, the braking device is at least temporarily and preferably always in an unbraked switching state during normal operation. In particular, the braking device is only in a braked switching state in the event of a malfunction. In particular, the braking device is only actuated by the malfunction protection device in the event of a malfunction.

[0029] In an alternative and equally advantageous embodiment, the braking device can also provide a braking torque during normal operation. Then, the braking device is also in a braked state at least temporarily during normal operation.

[0030] Switching state. It can be provided that the mobility of the steering unit can be braked by means of the braking device during normal operation exclusively with the emergency braking torque. If actuation of the braking device is intended during normal operation, the braking device preferably brakes exclusively with the emergency braking torque. This allows the braking device to be used, for example, to support the drive system during normal operation. At the same time, this functional extension is particularly safe, since even during normal operation, braking can only be carried out with the emergency braking torque.

[0031] However, it is also possible for the braking system to limit the mobility of the steering unit during normal operation with a defined braking torque that differs from the emergency braking torque and / or is adjustable (in particular, continuously). In particular, the adjustable braking torque is not greater than the maximum braking torque.

[0032] In particular, the braking device can be switched between a braked and an unbraked switching state. In particular, the braking device can only be switched between a (single) braked and a (single) unbraked switching state. This provides simple, yet very robust and reliable failure protection. In particular, the mobility of the steering unit in the unbraked switching state is not braked by the braking torque of the braking device. In particular, the mobility of the steering unit in the braked switching state is braked by the braking torque of the braking device.

[0033] In an advantageous embodiment, the braking device must be actively maintained in the unbraked switching state, particularly through the (continuous) use of supplied and / or stored energy. In particular, the braking device (autonomously) transitions to the braked switching state without the use of supplied and / or stored energy. This allows the emergency braking torque to be applied even in the event of a power failure, for example.

[0034] For example, the braking device brakes due to stored mechanical energy (e.g. spring energy) or magnetic energy (e.g. magnetic field of a permanent magnet or magnetizable components of the braking device). The brake is held in the unbraked switching state by supplied energy (e.g. current for an electrical coil device) or further stored energy (e.g. pressure accumulator). If the stored or supplied energy is no longer available, the braking device then automatically switches to the braked switching state. In order to return the brake to the unbraked switching state, for example a pressure accumulator must be charged or a magnetic field must be superimposed by another magnetic field of an electrical coil device.

[0035] The energy can be stored, for example, in a permanent magnet and / or a magnetized material of the braking device and / or in a spring-loaded device and / or a pressure accumulator or the like. The energy can be supplied, for example, electrically and / or magnetically and / or hydraulically and / or pneumatically or the like.

[0036] Preferably, the supply of the braking device with the supplied and / or stored energy can be specifically changed during normal operation. In particular, the braking torque provided during normal operation can be set by means of the changed energy supply. This means that the steering unit can be specifically braked during normal operation without adversely affecting the reliability of the emergency shutdown system. For example, the stored energy can be partially or completely released in order to brake the steering unit during normal operation. It is also possible for less energy to be specifically supplied during normal operation in order to generate a certain braking torque. For example, the reduced energy supply can reduce the magnetic field of a permanent magnet to a lesser extent, so that the braking device slows down the mobility of the steering unit.

[0037] In particular, the mobility of the steering unit can be slowed down by stopping the energy supply and / or discharging the stored energy. In particular, the emergency protection device is suitable and designed to interrupt the energy supply and / or discharge the stored energy in the event of an emergency, thereby transferring the braking device to the braked switching state.

[0038] In an advantageous embodiment, the braking device is in the unbraked switching state without the supply of energy. In particular, the braking device can be switched from the unbraked to the braked state (only) with the (continuous) supply of energy.

[0039] Switchable switching state. In particular, the braking device must be actively transferred to the braked switching state using energy. Particularly preferably, the energy required for this is stored in the emergency shutdown device. Such a design is particularly safe because the emergency shutdown device does not rely on external energy. In particular, the emergency shutdown device is suitable and designed to use the stored energy to actuate the braking device. In particular, the emergency shutdown device comprises at least one energy storage device.

[0040] It is possible for the energy supply to be specifically adjusted to set a braking torque intended for normal operation. In particular, energy is then also supplied to the braking device during normal operation, allowing it to generate a defined braking torque, preferably the emergency braking torque and / or a (continuously) adjustable braking torque.

[0041] In a particularly preferred and advantageous development, the braking device is designed magnetorheologically. In particular, the braking device comprises at least two braking components. In particular, at least one of the braking components can be rotated by the steering unit. In particular, at least one other of the braking components is supported in a rotationally fixed manner (e.g. on the drive device or on the vehicle side). In particular, at least one gap is formed between the braking components. The gap can also be referred to as an effective gap. In particular, the gap is at least partially filled with a magnetorheological medium. In particular, the medium can be specifically influenced by means of at least one field generating device. The advantages of the present invention can be particularly well utilized by means of such a magnetorheological braking device.

[0042] In particular, the magnetorheological medium can be specifically influenced by means of the field generating device in order to be able to adjust the mobility of the brake components relative to one another. In particular, the medium can be influenced by means of the field generating device in such a way that the mobility of the brake component can be subjected to a specific torque. The torque can also be zero. In particular, by influencing the mobility of the brake components, the mobility of the steering unit is also influenced. In particular, by braking the brake components, the steering unit is also braked. The steering input device can comprise at least one gear means which is suitable and designed to convert the movement of the steering unit into a rotational movement of one of the brake components.

[0043] The field generating device serves in particular to generate a magnetic field. In particular, the magnetic field extends at least through the gap and at least in sections through the regions of the brake components surrounding the gap. In particular, the magnetic field corresponds to a magnetic circuit or is part of such a circuit. The magnetic circuit is in particular a closed path of a magnetic flux within the brake device. The field generating device comprises in particular at least one electrical coil device and / or at least one permanent magnet device. The permanent magnet device comprises in particular at least one permanent magnet and / or at least one magnetizable material. In particular, a material of the brake components can be magnetizable and provide the permanent magnet device. In particular, the brake device comprises at least one magnetic circuit or can provide such a circuit.In particular, while the emergency braking torque is being provided (or in the braked switching state), the braking device has at least partial magnetic saturation, in particular of a magnetic circuit. A magnetic circuit is in particular a closed path of a magnetic flux. If a ferromagnetic body is magnetized, the magnetic forces initially increase proportionally to the strength of the magnetizing field. At some point, however, saturation is reached and the magnetic forces increase little or not at all. Saturation magnetization is the maximum possible magnetization of a material. In particular, the magnetic saturation is designed such that the maximum braking torque cannot be exceeded even if the field generating device provides a magnetic field that is stronger than the intended magnetic field due to a fault.This means that the braking device cannot safely and easily generate a braking torque that is greater than the maximum braking torque.

[0044] For example, due to a malfunction, an electrical coil device could be operated with a higher current or voltage than intended. Magnetic saturation in the magnetic circuit or a portion of the magnetic circuit prevents increased braking torque, and even in such a case, excessive braking of the steering unit does not occur. Magnetic saturation can be defined by the targeted material selection of the magnetic circuit (material type, cross-sections, shape) and / or the volume fraction of the magnetorheological medium (e.g., carbonyl iron). In particular, magnetic saturation is present at least in the sections of the brake components surrounding the gap.

[0045] The accident protection device preferably comprises at least one electrical energy store for supplying energy to the braking device in the event of a malfunction. In particular, the energy store provides at least the energy for the field generation device for influencing the magnetorheological medium. In particular, the energy from the energy store can be used to generate at least the accident braking torque. In particular, the energy store provides the energy for operating an electrical coil device (in particular generating a magnetic flux density). This means that, for example, even in the event of a power failure or a line break, reliable braking can be carried out and the vehicle can be driven safely onto the emergency lane or to the workshop. The energy store can comprise at least one capacitor device and / or at least one accumulator and / or at least one battery.

[0046] In particular, the energy storage device is arranged (at least partially) within the braking device. Preferably, the energy storage device is arranged within a housing of the braking device.

[0047] In an advantageous development, the emergency protection device comprises at least one permanent magnet device. In particular, the permanent magnet device provides at least one defined magnetic field. In particular, the magnetic field of the permanent magnet device influences the mobility of the brake components such that the mobility of the steering unit can be braked with the emergency braking torque.

[0048] Preferably, the magnetic field of the permanent magnet device can be reduced during normal operation by an electrical coil device. In particular, a defined magnetic field is generated for this purpose by means of the coil device, which is directed opposite to the magnetic field of the permanent magnet device. In particular, the magnetic field of the permanent magnet device can be reduced such that the braking device is in the unbraked switching state. In particular, the magnetic field can be reduced to such an extent that the mobility of the steering unit is no longer braked. In particular, the braking device then only has its basic torque.

[0049] If the braking device is also intended for braking during normal operation, the coil device can be used to reduce the magnetic field of the permanent magnet device even during normal operation to such an extent that the desired braking torque is achieved. In particular, the magnetic field generated by the permanent magnet device in the magnetic circuit is reduced or canceled by the (counter-rotating) magnetic field generated by the electrical coil device.

[0050] The permanent magnet device can be provided by a remanence device or at least comprise such a device. In particular, the remanence device is suitable and designed to specifically magnetize at least one component of the braking device, so that this component then provides a magnetic field (in the manner of a switchable permanent magnet). In particular, the component can also be demagnetized again (in particular by an electrical coil device).

[0051] The steering input device can comprise at least one control device which is suitable and designed to activate the braking device during normal operation to assist the drive device. As a result, the torque acting on the steering unit corresponds in particular to a sum of the torque of the drive device and the braking torque of the braking device. The braking torque of the braking device is in particular the emergency braking torque and / or the maximum braking torque. The torque of the drive device can also be zero. The braking torque of the braking device used can also be adjustable (in particular continuously). The drive device can therefore be made correspondingly smaller and thus lighter and more compact.

[0052] In particular, the control device is suitable and designed to activate the assistance to generate an end stop and / or to provide exit assistance and / or during a deflection of the steering unit from a neutral position and / or during rapid steering (evasive maneuvers). In such situations, the assistance offers particularly numerous advantages.

[0053] In particular, the assisting braking torque corresponds to the emergency braking torque and, particularly preferably, to the fixed emergency braking torque. It is also possible and advantageous for the assisting braking torque to be adjustable and, preferably, continuously adjustable.

[0054] The control device can be suitable and designed to adjust the braking torque provided for support as a function of a position of the steering unit and / or a movement parameter of the steering unit and / or an operating state of the vehicle and / or as a function of sensor signals and / or

[0055] Information / commands from a control unit and / or forces on the tie rod and / or virtual forces in a virtual vehicle (gaming vehicle / gaming application). In particular, the braking torque can be adjusted so that it complements the current torque of the drive system to produce a desired target torque.

[0056] In particular, the assistive braking torque can be adjusted by supplying the braking device with only a defined portion of the energy required to switch from a braked to an unbraked state. For example, this can be achieved by reducing the magnetic field of the permanent magnet device during normal operation by the electrical coil device only to the extent that the assistive braking torque is maintained.

[0057] The magnetorheological medium preferably comprises at least one metallic powder. In particular, the metallic powder has a volume fraction of at least 50% and preferably at least 60%. The metallic powder is preferably contained in a gaseous carrier medium, for example air. The metallic powder can also be contained in no carrier medium at all. The metallic powder is particularly preferably provided with a coating. By using such a medium, a particularly low base torque can be achieved. At the same time, due to the high volume fraction, a particularly high maximum braking torque can be achieved. In addition, such a medium can be used with consistent properties at the temperatures expected for the steering device. The metallic powder is preferably in the form of carbonyl iron powder (pure iron) or comprises at least one such powder.Other magnetorheologically responsive powders are also possible. Alternatively, the carrier medium can be a liquid, such as oil, in which the metallic powder is absorbed to form the magnetorheological medium.

[0058] In one embodiment, the steering input device can comprise at least two braking devices. In particular, at least a first of the at least two braking devices is provided (exclusively) for emergency protection. In particular, at least a second of the at least two braking devices is provided (exclusively) for braking the mobility of the steering unit during normal operation and / or for supporting the drive device during normal operation. With the second braking device, for example, an increased braking torque for end stops (end stop torque; maximum possible steering angle or maximum steering angle input) can be generated. This makes it possible to provide particularly precise and specifically controllable haptics for the steering movements. At the same time, the safety requirements can be implemented particularly easily and economically.

[0059] In particular, the second braking device has a maximum braking torque that is also lower than the maximum torque of the drive device. Preferably, the second braking device has a braking torque that is less than 6 Nm, preferably less than 4 Nm, and in particular a maximum of 3.6 Nm or 3.5 Nm. In particular, the second braking device is configured with respect to the braking torque as described for the first braking device. Thus, even in the event of a malfunction in the second braking device, excessive braking or even locking of the steering unit cannot occur.

[0060] In one possible design variant, the first brake unit can have a maximum braking torque of less than 2 Nm, and the second brake unit can also have a maximum braking torque of less than 2 Nm. This prevents sudden braking or even locking of the steering unit when both brakes are engaged. However, the user can clearly perceive a difference in the steering feel whether braking is performed with only one of the first and second brake units or with both brake units simultaneously. This allows, for example, end stops to be clearly represented haptically.

[0061] In particular, the second braking device is in the unbraked state in the event of a malfunction. However, the second braking device can also be available for emergency backup. In particular, the emergency backup is suitable and designed to selectively activate one of the at least two braking devices in the event of a malfunction. Such redundancy offers a particularly high level of safety.

[0062] In particular, the at least two braking devices, preferably the first and second braking devices, comprise a common gap or active gap. The at least two braking devices preferably also comprise two common braking components that are rotatable relative to one another. In other words, the at least two braking devices share the active gap and the common braking components. As a result, only two braking components and one active gap are required for two braking devices, not four.

[0063] In particular, the common effective gap is at least partially filled with the magnetorheological medium. In particular, the at least two braking devices each comprise at least one field generating device for generating a magnetic field. The at least two field generating devices each comprise, in particular, at least one electrical coil device and / or at least one permanent magnet device. The field generating devices are, in particular, designed as described above. In particular, the first braking device comprises at least one first field generating device. In particular, the second braking device comprises at least one second field generating device. The magnetic fields of the first and the second field generating device preferably act on the common effective gap.It is preferred that the first braking device is equipped with the permanent magnet device and the second braking device is equipped with the coil device.

[0064] In particular, the common active gap is configured to extend circumferentially around one of the brake components. The active gap may have at least one or at least two or more gap sections. The magnetic fields of the field-generating devices may act on the same gap section and / or on a different (adjacent) gap section of the active gap. In particular, the gap sections are interconnected and, in particular, fluidically connected.

[0065] In particular, the magnetic fields of the field generating devices run through the (common) braking components and the common effective gap (and in particular through the magnetorheological medium accommodated in the effective gap). The magnetic fields of the field generating devices preferably run through a common magnetic circuit. This means that in the event of a fault, the magnetic field of the first field generating device can be compensated for by the magnetic field of the second field generating device. This is very helpful, for example, in the event of an unwanted maximum current being applied to the coil device. This would not be (easily) possible with separate magnetic circuits. It is also possible and preferred for the magnetic fields of the field generating devices to each run through at least one of their own magnetic circuits and for these magnetic circuits to overlap at least in sections.In particular, the common brake components each provide at least a portion of the magnetic circuit. In particular, the magnetic circuits overlap at least in one of the common brake components and preferably in both common brake components.

[0066] In particular, the field lines within the magnetic circuit run parallel to one another, at least in some sections. In particular, the magnetic circuit has a homogeneous distribution of field lines (particularly compared to the field lines in air). In particular, the magnetic fields flow through a closed magnetic circuit.

[0067] The method according to the invention serves to operate a steering input device, as preferably described above. In particular, the method is designed such that the steering input device described here can be operated accordingly.

[0068] The applicant reserves the right to claim a steering system comprising a steering input device and an actuator device. The actuator device serves, in particular, to convert a steering movement performed by the steering unit into a vehicle movement. In particular, the steering unit and the actuator device are only operatively connected according to the steer-by-wire concept.

[0069] The steering input device can also be used to control a simulator or a computer simulation (e.g., in the manner of a computer game or for learning a skill). The applicant reserves the right to claim a steering input device for controlling a simulator or a computer simulation. In this case, the steering input device is designed, in particular, as previously described for the steering input device according to the invention.

[0070] The braking device can be designed as a mechanical, hydraulic, pneumatic, electrical, magnetic, and / or electromagnetic brake. The braking device can be designed as a friction brake or at least comprise one. In particular, the maximum braking torque or the emergency braking torque can be adjusted by selecting the friction force.

[0071] The braking device can comprise at least one energy storage device that provides the energy required to apply the emergency braking torque. The braking device can comprise a mechanical, hydraulic, pneumatic, electrical, magnetic, and / or electromagnetic energy storage device. For example, a (mechanical) spring, a pressure accumulator, a rechargeable battery, a battery, and / or a capacitor, or the like, can be provided. It is possible that the emergency braking torque or the maximum braking torque can be adjusted by selecting the energy storage device.

[0072] The drive device comprises, in particular, at least one drive motor. The drive device is, in particular, designed to be controllable so that the torque can be adjusted. A maximum torque of the drive device is understood, in particular, to be the maximum torque that the drive device can provide during normal operation. In particular, the maximum braking torque is less than the maximum torque that can be generated jointly by the braking device and the drive device.

[0073] In the context of the present invention, a malfunction of the drive device is understood in particular to mean that the drive device can no longer generate torque. In the event of a malfunction, the drive device in particular fails. For example, a power supply or control of the drive device is interrupted, or a drive motor is defective or can no longer be activated. In particular, the steering unit would be movable without resistance in the event of a malfunction if no malfunction protection were provided.

[0074] In particular, the braking device does not apply any braking torque during normal operation. In particular, the braking device applies only a base torque during normal operation. The base torque of the braking device is preferably less than 0.1 Nm, preferably less than 0.05 Nm, and particularly preferably less than 0.02 Nm. The base torque is determined in particular by technical factors, for example, by frictional forces or inertia forces.

[0075] In particular, the basic torque of the braking device is less than 1 Nm and preferably less than 0.5 Nm and particularly preferably close to zero.

[0076] Preferably, the switching time of the braking device is less than 10 ms. A switching time is defined in particular as the time between an inactive state (no braking torque; in particular, no magnetic field in the magnetic circuit) and an active state in which at least 90% of the maximum transmittable braking torque is available.

[0077] In particular, the steering input device comprises at least one control device. The control device is particularly suitable and configured to carry out the (method-like) steps described here using the means described here. In particular, the control device is operatively connected to the components of the steering input device, and in particular to the emergency shutdown device, the drive device, the braking device, and / or a sensor device.

[0078] Further advantages and features of the present invention will become apparent from the embodiments which are explained below with reference to the accompanying figures.

[0079] Therein show: Figure 1 a purely schematic representation of a steering input device according to the invention;

[0080] Figure 2 is a purely schematic representation of another steering input device according to the invention; and

[0081] Figure 3 is a purely schematic representation of a further steering input device according to the invention.

[0082] Figure 1 shows a steering input device 300 according to the invention for controlling a vehicle 330 (only partially shown here) according to the steer-by-wire concept. For this purpose, a steering unit 301, embodied here as a steering wheel 311, is electrically or electronically connected to an actuator device 307. The actuator device 307 can, for example, adjust one or two or more wheels of the vehicle 330 and thereby convert the steering movement executed by the steering unit 301 into a vehicle movement. The steering input device 300 is operated here according to the method according to the invention.

[0083] The movement or position of the steering unit 301 is detected here by a sensor device 70 and, for example, by a rotation angle sensor. Depending on a sensor signal from the sensor device 70, the steering movement is then implemented accordingly by the actuator device 307.

[0084] The steering presetting device 300 comprises a drive device 302 with an electric drive motor 312, which is connected to the steering unit 301 via a steering shaft 322. This generates a torque acting on the steering unit 301, so that the steering unit 301 can be actively turned to the right or left. The drive device 302 can also be used to simulate forces such as those that would be felt on the steering unit 301 with a mechanical steering system. For this purpose, a torque acting on the steering unit 301 (so-called passive torque) is generated, which counteracts the manual movement.

[0085] The steering preset device 300 is equipped with a failure protection device 305 so that the steering unit 301 cannot be moved without resistance, for example, in the event of a failure of the drive device 302. For this purpose, the failure protection device 305 has a braking device 1 independent of the drive device 302, which can brake the mobility of the steering unit 301 with a targeted braking torque, the so-called failure braking torque. The braking device 1 is flanged to the drive motor 312 of the drive device 302. The drive motor 312 is attached to a vehicle-side support structure.

[0086] The failure protection device 305 shown here can not only prevent the steering unit 301 from being moved without resistance. It can also ensure, with exceptional reliability, that the steering unit 301 is not blocked in the event of a failure of the drive device 302. For this purpose, the braking device 1 has a maximum braking torque that is deliberately smaller than the maximum torque of the drive device 302.

[0087] The maximum braking torque of braking device 1 here is 3.5 Nm or less. This maximum braking torque also corresponds to the emergency braking torque. The emergency braking torque, for example, is fixed and cannot be adjusted. In the event of a failure of the drive device 302, the emergency protection device 305 actuates braking device 1, causing it to switch from an unbraked to a braked switching state, and the steering unit 301 then brakes with the emergency braking torque of 3.5 Nm.

[0088] With a maximum braking torque of 3.5 Nm or less, the steering unit can be operated manually without any problems. For braking torques above 3.5 Nm, additional technical standards must generally be met, which in turn place increased requirements on the failure of the braking device 1. This can be prevented with the braking device 1 presented here, which is limited in its maximum braking effect to the stated range. The braking device 1 shown here can always be safely over-rotated using normal muscle force. The braking device 1 is designed purely as an example as a magnetorheological braking device 1. It comprises two braking components 2, 3 which can be rotated relative to one another and between which a circumferential gap 5 is formed. A magnetorheological medium 6 is arranged in the gap 5. The medium 6 can be specifically influenced by means of a field generating device 16.For this purpose, a magnetic field is generated by the field generating device 16, which acts on the medium 6. The magnetic field influences the medium 6, which in turn influences the mobility of the brake components 2, 3.

[0089] For example, the stronger the magnetic field in gap 6, the more the movement is braked. The relative mobility of the brake components 2, 3 can be braked so that they can rotate freely (with the base torque) or braked with the maximum braking torque. This process can be reproduced as often as required, is silent, and wear-free.

[0090] In the version shown here, the emergency stop device 305 is equipped with a permanent magnet device 325. This device generates a magnetic field in gap 5, for example, using a permanent magnet. This influences the medium 6 in such a way that the mobility of the brake components 2, 3 (and thus also the steering unit 301) is braked with the emergency braking torque. As a result, the braking device 1 automatically assumes the braked switching state. For normal operation, the braking device 1 must then be actively maintained in the unbraked switching state with a power supply.

[0091] During normal operation, the magnetic field of the permanent magnet device 325 is superimposed by a corresponding magnetic field and (essentially) eliminated. The magnetic field for the superimposition is generated here by an electrical coil device 26. For the unbraked switching state, current must be supplied to the coil device 26. If a malfunction occurs, the coil device 26 is deactivated, and the steering unit 301 is automatically braked with the malfunction braking torque. The electrical coil unit, including the magnetic circuit and operating principle, are optimized and designed for minimal power / energy consumption, so that little power is required in the event of a malfunction, preferably less than 10 watts, particularly preferably less than 1 watt.

[0092] In addition to or as an alternative to a permanent magnet, the permanent magnet device 325 can also be provided by a remanence device. This can magnetize a component of the braking device 1 such that the component provides a magnetic field even without additional power supply (e.g., AlNiCo). For example, the coil device 26 is used here to magnetize the component. The magnetic field for superimposition during normal operation is also generated by the coil device 26.

[0093] The fault protection device 305 shown here can also be designed such that the braking device 1 is in the unbraked switching state when no power is supplied. For this purpose, no magnetic field is generated during normal operation, and the braking components 2, 3 are freely rotatable relative to one another, except for a base or idling torque. In the event of a fault, a magnetic field is then generated by the coil device 26, so that the steering unit 301 is braked with the fault braking torque.

[0094] The energy required for the coil device 26 in the event of a malfunction is stored here in an electrical energy storage device 335 of the malfunction protection device 305. This can be arranged inside or outside the braking device 1 and comprises, for example, an accumulator, capacitor or battery or a combination thereof. The energy storage device 335, which is only shown schematically in the figures for illustrative reasons, is preferably arranged inside, i.e. in the housing of the braking device 1, so that no cables or connections between the energy storage device 335 and the braking device 1 lie outside the housing. The braking torque can thus be generated independently of the vehicle's main power supply (storage capacity, for example, 20h).

[0095] Preferably, the components of the braking device 1 through which the magnetic field extends during operation (magnetic circuit) are made of a material with a particularly low residual field (close to zero) and, in particular, with no residual field (no residual magnetism - no magnetism remains in the magnetic circuit). For example, silicon steel and / or soft magnetic cobalt-iron alloys (such as Vacoflux, a 17% or 49% cobalt-iron alloy) are used for this purpose. These materials can be used in solid or massive form or in powder form (e.g., for sintering).

[0096] The braking device 1 shown here has the particular advantage that, for technical reasons, it cannot exceed the fault braking torque of 3.5 Nm (or its maximum braking torque). Even when energized with a current exceeding the rated current (in the event of a fault), the braking torque never exceeds the maximum braking torque. This is because the components magnetizable by the coil device 26 are in a state of magnetic saturation when the maximum braking torque is generated. Even in the version with the permanent magnet device 325, the maximum braking torque cannot be exceeded.

[0097] In an advantageous embodiment, the braking device 1 can act with the predefined, in particular constant, emergency braking torque or maximum braking torque exclusively in the event of a failure of the drive device 302. The braking device 1 can be switched between the switching states "unbraked" and "braked" (energizing the coil device 26 with a constant current, resulting in the corresponding emergency braking torque). During normal operation, the braking device 1 is not activated and thus, apart from any design-related basic friction (= basic torque), does not introduce any braking torque into the steering shaft 322. In the event of a failure, the steering unit 301 can be subjected to a braking torque from the braking device 1, for example, if the steering unit 301, starting from a neutral position (straight-ahead travel), acts in one direction of rotation toward one of the end stops and is deactivated in the opposite direction until the neutral position is reached.This allows a particularly constant braking torque to be applied when steering unit 301 is deflected from the neutral position, while the steering unit 301 moves smoothly when returning to the neutral position. If the neutral position is then left in the opposite direction of rotation, the braking torque is activated. This allows a rudimentary haptic response to be provided in the event of a malfunction.

[0098] In one embodiment, the braking device 1 can also be operated in combination with the drive device 302 to influence the torque flow in the steering shaft 322. For example, the end stop and / or the exit aid can be used with the braking device 1 to increase the torque. The drive device 302 can be dimensioned accordingly smaller.

[0099] For example, it is also possible to use a counter-torque component during the deflection of the steering unit 301 from the neutral position by means of the braking device 1. The drive device 302 can then be dimensioned accordingly smaller.

[0100] Optionally, the braking device 1 can exert a braking torque on the steering unit 301 that is adjustable between the idle torque and the maximum braking torque, in particular continuously (during normal operation, when steering). This allows actuation to be free of play and jerks, etc. The drive device 302 can then be dimensioned accordingly smaller.

[0101] The braking device 1 can also share the steering work (force feedback work) with the drive device 302 or a main unit (torque management; shared torque; haptically, safety-related and energetically advantageous

[0102] Allocation / distribution of the active (e.g., torque of the drive device 302) and passive (braking torque of the braking device 1) torque). The drive device 302 should be designed somewhat stronger so that the torque requirements can be met accordingly.

[0103] Figure 2 shows an embodiment of the steering presetting device 300 with a braking device 1, which is arranged here between the drive motor 312 of the drive device 302 and the steering unit 301.

[0104] Figure 3 shows an embodiment of the steering input device 300 with a first and a second braking device 1, 10. The first braking device 1 serves for the emergency protection 305 and is designed as previously described. The second braking device 10 serves to support the drive device 302 during normal operation. The second braking device 10 also has a maximum braking torque of equal to or less than 3.5 Nm.

[0105] In the event of a fault, the second braking device 10 is in the unbraked switching state and thus only provides the base torque. However, due to its maximum braking torque, the second braking device 10 can also advantageously serve as a redundant brake in the event of a fault.

[0106] The braking devices 1, 10 can, for example, be connected in series. The braking devices 1, 10 can then, together with the drive device 302 or the main unit, apply the maximum passive torque during normal operation (torque management). The braking devices 1, 10 preferably contribute the majority of this.

[0107] The previously described steering control devices 300 can be equipped with a steering lock 306, which mechanically blocks the mobility of the steering unit 301. This allows a person to lean on the steering unit 301 when getting in or out of the vehicle. For example, the steering lock 306 comprises a bolt or the like, which is attached to a support structure of the vehicle 330 (not shown in detail here) and extends into the steering shaft 322.

[0108] As an alternative to the magnetorheological design, the previously described steering input devices 300 can also be equipped with a mechanical braking device 1 for the emergency protection 305. This can be, for example, a spring-loaded mechanical brake with a maximum braking torque within the range specified above. For example, a friction brake is provided, which is released during normal operation, for example, electromagnetically, hydraulically, or pneumatically. The braking torque can be adjusted by selecting the appropriate springs.

[0109] The invention presented here enables a particularly safe, yet robust, space-saving, and cost-effective implementation of steer-by-wire steering requirements. Safety regulations (e.g., ADAS; ASIL B to D) are much stricter for force-feedback units that generate torques (active torques) that cannot be (easily) overcome by muscle power than for systems that (only) generate braking torques (passive torques) and / or can be safely over-torqued manually.

[0110] The driver can still easily and safely over-react the maximum braking torque described here. This means that if 3.5 Nm are applied to the steering wheel when the failure protection 305 is active, the vehicle can still be steered easily and safely. Even in the event of a sudden failure, the driver will not be too startled (= safe) if this torque is applied, as it is not far from the torque during normal operation. A sudden return to the base torque (< 1 Nm or < 0.1 Nm) would lead to over-steering due to the extreme ease of movement. If the drive device 302 fails, the braking device 1 can intervene, which is designed such that it only delivers, for example, 3.5 Nm of braking torque when fully energized. The braking device 1 then goes into magnetic saturation in the magnetic circuit. This means that even (unforeseen) very high (failsafe) currents in the coil device 26 do not lead to more braking torque.

[0111] The chain formation of the (carbonyl iron) particles can be "over-torqued" without any disadvantages. If more than 3.5 Nm of torque is applied to the steering unit 301, nothing can be damaged. Neither up to nor above 3.5 Nm can locking or jamming occur, since the completely freely movable carbonyl iron particles are always located between the (solid metallic) brake components 2, 3 rotating relative to each other.

[0112] If the magnetic field is then generated by a power storage device (battery / accumulator / capacitor), a fallback level is created that functions reliably even in the event of a power failure of the main power supply. Braking device 1 can then either provide a constant current (= constant torque) or be controlled via a compact electronics characteristic (e.g., a lookup table). This even eliminates the need for a sensor or rotary encoder and a torque sensor. This results in a very cost-effective and robust fallback level in the event of a failsafe.

[0113] This solution can also be combined with the drive unit 302 during normal operation, thereby increasing the maximum torque (e.g., 3.5 Nm drive motor plus 3.5 Nm brake unit = 7 Nm maximum torque). This is sufficient in most cases of normal operation.

[0114] In addition, the emergency shutdown device 305 can intervene with its braking device 1 if the drive device 302 malfunctions and would rotate too strongly or / and against the driver's wishes in a (wrong) direction with torque. The braking device 1 can then brake in the opposite direction and, for example, prevent the steering unit 301 from being torn from the driver's hand or the operator's steering wishes from being adversely distorted.

[0115] The steering command devices 300 shown here can also be equipped with a steering unit 301 designed as a handlebar, steering wheel, joystick, or the like. The actuator device 307 is designed accordingly for the respective steering unit and is then used, for example, to actuate the tail unit of an aircraft or the rudder of a ship. Likewise, the steering command devices 300 shown here can also be designed to control a simulator or a computer simulation. The steering command devices 300 presented here therefore do not necessarily have to be operatively connected to an actuator device 307, which serves to control a real vehicle 330. In a simulator, the actuator device 307 can be omitted entirely, for example. Rather, the signals from the steering command device 300 are converted into a simulated or virtual scenario.

[0116] The explanations for Figs. 1 to 3 refer to applications in passenger cars as an example. In other applications, e.g., when used in trucks or larger vehicles, the emergency braking torque can be higher, e.g., max. 6 Nm or less. Apart from the optionally higher emergency braking torque value for trucks, the explanations for Figs. 1 to 3 also apply equally to applications with an emergency braking torque of more than 3.5 Nm (e.g., 6 Nm or less). List of reference symbols:

[0117] 1 braking device 307 actuator device

[0118] 2 , 3 Brake component 308 Control device

[0119] 5 gap 311 steering wheel

[0120] 6 Medium 312 drive motor

[0121] 10 Brake device 322 Steering shaft

[0122] 16 Field generating device 325 permanent magnet

[0123] 26 Coil device device

[0124] 70 Sensor device 330 Vehicle

[0125] 300 Steering control device 335 Energy storage

[0126] 301 steering unit

[0127] 302 drive device

[0128] 305 Fault fuse

[0129] 306 steering lock

Claims

Claims:

1. Steering control device (300) for specifying a steering movement according to the steer-by-wire concept, comprising at least one movable steering unit (301), in particular a steering wheel (311), and at least one drive unit (302) for generating a torque acting on the steering unit (301) and at least one fault protection device (305), which serves to ensure that the steering unit (301) is neither blocked nor can be moved without resistance in the event of a fault in the drive unit (302), characterized in that the fault protection device (305) comprises at least one braking device (1) independent of the drive unit (302), the maximum braking torque of which is less than a maximum torque of the drive unit (302), and that the fault protection device (305) is suitable and configured to actuate the braking device (1) in the event of a fault in the drive unit (302) and thereby prevent the movement of the steering unit (301) with a targeted braking torque.so-called emergency braking torque, to brake.

2. Steering guidance device (300) according to the preceding claim, wherein the maximum braking torque of the braking device (1) less than 6 Nm, preferably less than 4 Nm, and particularly preferably a maximum of 3.5 Nm.

3. Steering guidance device (300) according to the preceding claim, wherein a maximum tangential force on the steering guidance device (300) caused by the braking device (1), which opposes an operating force of a user at an application point of the steering unit (301), is less than 30 N and preferably a maximum of 20 N.

4. Steering guidance device (300) according to one of the preceding claims, wherein the maximum braking torque is controlled by the The steering control device (300) corresponds to the fault braking torque, such that the movement of the steering unit (301) is braked by means of the braking device (1) with the maximum braking torque in the event of a fault in the drive device (302). The steering control device (300) according to one of the preceding claims, wherein the basic torque of the braking device (1) is less than 0.1 Nm and preferably less than 0.05 Nm. The steering control device (300) according to one of the preceding claims, wherein the braking device (1) cannot, for technical reasons, apply a braking torque higher than the maximum braking torque, wherein the maximum braking torque corresponds to the fault braking torque, so that even in the event of a fault in the braking device (1) the maximum braking torque cannot be exceeded. The steering control device (300) according to one of the preceding claims, wherein the braking device (1) has a fixed, predetermined fault braking torque.Steering guidance device (300) according to one of the preceding claims, wherein the movement of the steering unit (301) by means of the braking device (1) can be braked either only with the fault braking torque or not at all. Steering guidance device (300) according to one of the preceding claims, wherein the movement of the steering unit (301) by means of the braking device (1) can be braked only in the event of a fault and wherein the movement of the steering unit (301) cannot be braked by means of the braking device (1) during normal operation. Steering guidance device (300) according to one of the preceding claims, wherein the braking device (1) is switchable between a braked and an unbraked switching state and wherein the braking device (1) is actively engaged. The braking device (1) must be maintained in the unbraked switching state by means of supplied and / or stored energy, and wherein the braking device (1) transitions to the braked switching state without the use of supplied and / or stored energy. Steering control device (300) according to the preceding claim, wherein the supply of supplied and / or stored energy to the braking device (1) can be selectively varied during normal operation, and wherein a braking torque provided for in normal operation can be adjusted by means of the varied energy supply. Steering control device (300) according to one of the preceding claims, wherein the braking device (1) is in the unbraked switching state without energy supply, and wherein the braking device (1) can be switched from the unbraked to the braked switching state (only) by means of energy supply, and wherein the energy required for this is stored in the fault protection device (305).Steering guidance device (300) according to one of the preceding claims, wherein the braking device (1) is magnetorheological and comprises at least two braking components (2, 3), wherein at least one of the braking components (2, 3) is rotatable by the steering unit (301) and wherein at least one other of the braking components (2, 3) is supported in a rotationally fixed manner, and wherein at least one gap (5) at least partially filled with a magnetorheological medium (6) is formed between the braking components (2, 3), and wherein the medium (6) can be selectively influenced by means of at least one field generation device (16). Steering guidance device (300) according to the preceding claim, wherein the braking device (1) has at least sectionally magnetic saturation during the provision of the emergency braking torque, and wherein The magnetic saturation is designed such that the maximum braking torque cannot be exceeded even if the field generation device (16) provides a magnetic field stronger than a specified magnetic field due to a fault. Steering control device (300) according to one of the two preceding claims, wherein the fault protection device (305) comprises at least one electrical energy storage device (335) for supplying energy to the braking device (1) in the event of a fault, and wherein the energy storage device (335) provides at least the energy for the field generation device (16) to influence the magnetorheological medium (6) so that the fault braking torque can be generated. Steering control device (300) according to the preceding claim, wherein the energy storage device (335) for the braking device (1, 10) is located within a housing of the braking device (1, 10).Steering guidance device (300) according to one of the three preceding claims, wherein the fault protection device (305) comprises at least one permanent magnet device (325) whose magnetic field influences the mobility of the brake components (2, 3) such that the mobility of the steering unit (301) can be braked with the fault braking torque, and wherein the magnetic field of the permanent magnet device (325) can be reduced in normal operation by an electrical coil device (26) so that the brake device (1) is in an unbraked switching state. Steering guidance device (300) according to one of the preceding claims, comprising at least one control device (308) which is suitable and configured to activate the brake device (1) in normal operation to support the drive device (302), so that the... The torque acting on the steering unit (301) corresponds to the sum of the torque of the drive unit (302) and the braking torque of the brake unit (1). Steering assist device (300) according to the preceding claim, wherein the assistance can be provided to generate an end stop and / or to provide an exit aid and / or during deflection of the steering unit (301) from a neutral position. Steering assist device (300) according to one of the two preceding claims, wherein the braking torque used for assistance is the fixed, predetermined fault braking torque, or wherein the braking torque used for assistance is adjustable and preferably continuously adjustable.Steering guidance device (300) according to one of the three preceding claims, wherein the assisting braking torque is adjustable by supplying the braking device (1) with only a defined portion of the energy required to switch from a braked to an unbraked switching state. Steering guidance device (300) according to claim 13, wherein the magnetorheological medium (6) comprises at least one metallic powder and wherein the metallic powder has a volume fraction of at least 50% and preferably at least 60% and / or wherein the metallic powder is contained in a gaseous or no carrier medium.Steering guidance device (300) according to one of the preceding claims, comprising at least two braking devices (1, 10), wherein at least one first of the at least two braking devices (1, 10) is provided for the fault protection (305) and wherein at least one second of the at least two braking devices (1, 10) serves to brake the mobility of the steering unit (301) in normal operation.

24. Method for operating a steering control device (300) according to one of the preceding claims.

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