Cascaded vernier algorithm in a metrologically used two-stage gearing

Abstract

The invention relates to a steering actuator and to a method for a steer-by-wire system for determining a position of a lifting rod (201) for steering purposes, comprising: - a measuring gearing (10) having a first axis of rotation (11), a second axis of rotation (12) and a third axis of rotation (13), - a first sensor (21) for ascertaining a first position (31) of the first axis of rotation (11), - a second sensor (22) for ascertaining a second position (32) of the second axis of rotation (12), - a third sensor (23) for ascertaining a third position (33) of the third axis of rotation (13), - a control unit (ECU) for receiving the first position (31), the second position (32) and the third position (33), wherein the control unit (ECU) is configured: o to calculate a first vernier function (N1) in order to obtain a first result (E1), o to calculate a second vernier function (N2) in order to obtain a second result (E2), o to calculate a third vernier function (N3) in order to obtain a third result (E3), and o to operate the steering actuator (100) on the basis of the third result (E3).

Description

[0001] Cascaded vernier algorithm for a two-stage gearbox used for measurement purposes

[0002] Description

[0003] The invention relates to a steering actuator having the features of independent patent claim 1, a method having the features of independent patent claim 10, a computer program product having the features of independent patent claim 12, a computer-readable data carrier having the features of independent patent claim 13, a control unit having the features of independent patent claim 14 and a vehicle having the features of independent patent claim 15.

[0004] Steering actuators are known which support the driver's manual steering movement on a steering wheel. This is primarily used when there is a (physical) connection between the steering wheel and a rack (via which the angle of the wheels is adjusted) via a steering column. In steer-by-wire systems, this steering column is missing. Therefore, not only steering support is required, but a complete positioning control loop via which a steering torque or steering angle is specified by the steering wheel, and then a lifting rod (often no longer called a rack due to the lack of teeth) is positioned. In the lower area of ​​the lifting rod, this can be achieved by a so-called road wheel actuator (RWA). The steer-by-wire system can therefore comprise a road wheel actuator (RWA, in particular for operating a lifting rod) and a hand wheel actuator (HWA, in particular comprising a decoupled steering wheel).In previous designs with a mechanical axis between the steering wheel and the rack (e.g., EPS, Electric Power Steering), only torque assistance was provided. With a steer-by-wire system, a positioning task may need to be solved instead. In other words, the position of the lifting rod must be known and can be adjusted during operation. However, this requires precise knowledge of the position of the rack and the components connected to it. A drive device is required to move the lifting rod, with a

[0005] REPLACEMENT SHEET (RULE 26) The motor-gearbox combination can be operated with a high gear ratio to generate the required power. The gearbox often consists of several stages of different gear topologies.

[0006] However, the devices and methods for determining position known from the prior art have a number of disadvantages. For example, a gearbox may be necessary to transmit the power from a drive device to the lifting rod. The resulting disadvantage is the ambiguity of the sensor information. While the information at the lifting rod is still unambiguous, it has already become ambiguous at the first gear stage. Today, it can be assumed that around 100 revolutions are required on the power pack or drive device to adjust the steering of a typical car from the right steering lock to the left steering lock. In order to integrate a position sensor into the power pack, it is therefore necessary to resolve this ambiguity of around 100 revolutions in the power pack. Since the position, particularly of rotationally symmetrical components, repeats itself after a rotation of 360°, a differentiation orPrecise, absolute information about the position of the lifting rod is not possible, and in particular it is not unambiguous. In other words, ambiguity can arise when determining the position (or measuring the angle). Single-stage transmissions, particularly those with high gear ratios, which, for example, use a large gear that does not complete a full rotation even when the wheels are fully turned from left to right, do not have sufficient accuracy; in particular, measurement (from a metrological perspective) can be impossible. For example, it can be provided that a drive device rotates from left to right dead center (i.e., full steering angle of the wheels) at approximately 100 revolutions. Accordingly, an accuracy of approximately 1 / 100 would be necessary. However, it is expensive and / or complicated to provide such precise measuring devices. Furthermore, the installation space for such transmissions can be unfavorable (e.g. due to the size of the gear).A further disadvantage can be that measurements are often taken on the steering rack (or lifting rod). However, since these deform, particularly under load (e.g., by 20 mm perpendicular to their extension), a (position) measurement can be inaccurate. Furthermore, this can lead to severe mechanical stress on the sensors used. Accordingly, corresponding sensors can be heavy, large, and / or expensive. In addition, existing devices can generate a relatively high level of noise, for example, because they have to be robust and / or structurally large. Furthermore, known devices often rely on (stored) reference values ​​for the position, which can be particularly disadvantageous if the memory is erased (e.g., when the battery is disconnected) and / or if the wheel angle is changed unnoticed (e.g., on a lifting platform during vehicle maintenance).

[0007] It is therefore an object of the present invention to at least partially overcome at least one of the disadvantages described above. In particular, the object of the invention can be to provide position measurement with greater accuracy. Furthermore, a reduction in installation space, weight, costs, and / or (operating) noise can be provided. Furthermore, it can be provided to calculate back ambiguities over a larger range, particularly when using gears, in order to be able to determine an exact position (e.g., of the lifting rod). Furthermore, it can be an object to determine the position without memory, reference, and / or prior knowledge.

[0008] The above object is achieved by a steering actuator having the features of independent patent claim 1, by a method having the features of independent patent claim 10, by a computer program product having the features of independent patent claim 12, by a computer-readable data carrier having the features of independent patent claim 13, by a control unit having the features of independent patent claim 14 and by a vehicle having the features of independent patent claim 15. Further features and details of the invention emerge from the subclaims, the description and the drawings.In this case, features and details which are described in connection with the steering actuator according to the invention naturally also apply in connection with the method according to the invention and / or in connection with the computer program product according to the invention and / or in connection with the computer-readable data carrier according to the invention and / or in connection with the control unit according to the invention and / or in connection with the vehicle according to the invention and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is or can always be made mutually.

[0009] According to the invention, a steering actuator for a steer-by-wire system for determining a position of a lifting rod for steering is provided, comprising:

[0010] - a measuring gear with a first rotational axis, a second rotational axis coupled to the first rotational axis, and a third rotational axis coupled to the first rotational axis,

[0011] - a first sensor for detecting a first position of the first axis of rotation,

[0012] - a second sensor for detecting a second position of the second axis of rotation,

[0013] - a third sensor for detecting a third position of the third axis of rotation,

[0014] - a control unit for receiving the first position, the second position and the third position, wherein the control unit is designed: o to calculate a first vernier function based on the first position and the second position in order to obtain a first result, o to calculate a second vernier function based on the first position and the third position in order to obtain a second result, o to calculate a third vernier function based on the first result and the second result in order to obtain a third result, o to operate the steering actuator based on the third result. The steering actuator can be a so-called road wheel actuator (RWA). The steering actuator can therefore be used to adjust the wheel angle (e.g. for steering a vehicle) by positioning a lifting rod, in particular in steer-by-wire operation.

[0015] The steering actuator can be used to determine the position, in particular of the lifting rod. For this purpose, the position, for example an angular position, of the first, second, and / or third rotational axes can be determined. This can (without the solution according to the invention) lead to the ambiguities described above, in particular, which are attributable to the periodicity or repetition in rotationally symmetrical components. The first, second, and / or third rotational axes can preferably be designed to be rotationally symmetrical. This allows for simple manufacturing and / or uniform rotation.

[0016] The first, second, and / or third rotational axes can be configured essentially parallel. This can result in an optimized design of the installation space, allowing, for example, an elongated and / or flat extension. Furthermore, this can lead to simple and / or cost-effective production.

[0017] In this case, particularly in the case of the measuring gear, it can preferably be a two-stage gear with three axes of rotation. This can advantageously lead to a lower (necessary) accuracy of the individual components without reducing the overall accuracy. For example, a two-stage gear (as described above) may require an accuracy of 1 / 100, which is technically difficult to achieve, e.g., for a large gear. A two-stage gear can also have an accuracy of approximately 1 / 100, particularly due to the larger number of axes of rotation and / or gears, even if the accuracy of the individual components is, for example, only 1 / 10. In particular, with the present invention, high accuracy can be achieved due to the nested vernier functions, especially even if the components individually have a lower accuracy (e.g., compared to a two-stage solution).Coupling can be achieved, in particular, by means of gearing. A first gear can be arranged in a rotationally fixed manner on the first axis of rotation (see below). A second gear can be arranged in a rotationally fixed manner on the second axis of rotation. A third gear can be arranged in a rotationally fixed manner on the third axis of rotation. Adjacent gears are preferably intermeshed, which leads to a transmission of the rotational movements. The gears can preferably be rotationally symmetrical. This allows for simple manufacturing and / or uniform rotation.

[0018] Within the scope of the invention, it can be advantageous for the steering actuator to have a drive device, in particular an electric motor, for driving a lifting rod for steering, wherein a rotary shaft of the drive device preferably substantially coincides with, in particular is identical to, the first axis of rotation. It can also be provided that the first axis of rotation is coupled to the rotary shaft. The measuring gear can be used as a purely metrological gear. This can make it simpler and / or more cost-effective. The measuring gear and / or the sensors can be integrated into the drive device. This can save installation space and / or reduce costs.

[0019] The steering actuator can have a control unit and a drive device (also called a power pack). The drive device is preferably an electric motor, preferably a brushless one. This can minimize wear and / or maximize efficiency. The electric motor can, for example, be operated at around 12V and 100A. This means that comparatively large forces can arise. The sensors or the measuring gear are preferably not exposed to these forces or are only partially exposed to them in order to advantageously use less robust, smaller and / or less expensive materials. In addition, a more precise measurement can be achieved when fewer forces are acting, for example because less deformation occurs which could influence the position measurement. The steering actuator (orThe power pack (the power pack) can comprise, in addition to a brushless motor, the necessary electronics for control. In particular, the power pack's electronics can include an output stage in the form of a so-called B6 bridge, a control logic for this output stage through an intelligent driver stage (called Gate Driver Unit (GDU), a microcontroller as a computing unit for control, communication and regulation, a position sensor for motor control and / or various interfaces for mostly bus systems such as the CAN bus for communication with the outside world. The rotating shaft can be aligned essentially parallel to a lifting rod of the vehicle. This can result in a particularly compact design.

[0020] Within the scope of the invention, it is conceivable that the first sensor, the second sensor and / or the third sensor are designed as multi-pole sensors, wherein these in particular provide at least two periods over a full revolution.

[0021] The first, second, and / or third sensor can be enclosed by and / or integrated into the measuring gear. These can be integrated with additional electronics in the power pack. Interfaces can be simplified and / or connections no longer need to be protected against surges, short circuits, and / or interchanged cables, as is the case with external sensors, for example. Shorter connections can also improve and / or circumvent the radiation immunity and / or the coupling of electromagnetic interference via lines.

[0022] The first, second and / or third sensor can enable the detection of the position, in particular angular position, of the first, second and / or third axis of rotation.

[0023] The first, second, and / or third sensors can essentially deliver a sawtooth signal, which repeats periodically, in particular after one rotation (360°). A multi-pole sensor can have at least two, preferably identical and / or opposing, vanes. It may be particularly preferred to use three vanes. In other words, such a 3-point division can provide a periodicity of 120°. This can influence the number of revolutions required to achieve phase identity with another axis of rotation. With a larger number of poles or vanes, the number of periods delivered over a full rotation (e.g., of a rotation axis) can increase. Additionally or alternatively, a more uniform running can be enabled. The sensors or the poles of the sensors can preferably be integrated on and / or in a gear.For example, the first sensor can be at least partially integrated on / or in the first gear. For example, the second sensor can be at least partially integrated on / or in the second gear. For example, the third sensor can be at least partially integrated on / or in the third gear. It can be provided that the first, second and / or third sensor each have a first, second and / or third position detection device, which preferably detects the poles located in the respective gear. The position detection device can be arranged in a stationary manner in order to enable position measurement, particularly in interaction with the rotatable components of the sensor. The structural proximity of the sensors and / or their design can result in simplification and / or cost savings. This also makes it possible to provide a more robust device.

[0024] It may be particularly preferred if the second and third sensors are designed as multi-pole sensors.

[0025] It may be particularly preferred if the first, second and / or third sensor are designed as inductive sensors or comprise an inductive sensor.

[0026] It may be particularly preferred if the first, second, and / or third sensors are designed as pure position sensors. It may be provided that no torque is measured. This allows for a simpler, more cost-effective, and / or more robust design of the sensors.

[0027] It can be provided within the scope of the invention that the first sensor can be arranged (or arranged) on or in the first axis of rotation, the second sensor can be arranged (or arranged) on or in the second axis of rotation, and / or the third sensor can be arranged (or arranged) on or in the third axis of rotation, wherein preferably the axes of rotation, sensors and / or the control unit are compactly integrated in the steering actuator.

[0028] This allows the sensors to precisely monitor the (rotational) movements of the rotation axes.

[0029] This can result in a compact and integrated steering actuator. This can advantageously save weight, cost, and / or installation space. It can be replaced modularly. It can be designed to eliminate the need for additional external electronics and / or sensors. This can provide a particularly durable and / or well-protected system. This advantageously avoids complicated and / or wear-prone measurements on a lifting rod.

[0030] The device can be used alternatively or in addition to a position measurement on a lifting rod (e.g., using a linear position sensor). Preferably, a measurement can be enabled downstream of additional gear stages of the drive device.

[0031] It is further conceivable for the first rotational axis to have a first gear, which can be arranged centrally, in particular, the second rotational axis to have a second gear, which can be coupled to the first gear in a toothed manner, and the third rotational axis to have a third gear, which can be coupled to the first gear in a toothed manner. The first and second rotational axes, in particular the first and second gears, can preferably not be in direct contact with one another and / or coupled, but preferably only with the first rotational axis, in particular the first gear.

[0032] Preferably, the first, second, and / or third gears are located essentially in one plane. This minimizes installation space.

[0033] It is also conceivable that the measuring gear has a spur gear.

[0034] This can preferably be a two-stage gearbox with three axes of rotation.

[0035] A spur gear unit can enable particularly compact and / or cost-effective production. In particular, the design can be advantageous due to its elongated extension, for example, enabling particularly space-saving integration into an overall system.

[0036] Other gear topologies such as belt drives, planetary gears or worm gears can also be provided.

[0037] Within the scope of the invention, it is optionally possible for the first gear, the second gear, and / or the third gear to be substantially the same size and / or have substantially the same number of teeth. This can mean, for example, that the number of teeth is 30, 31, 33. Thus, the number of teeth can be substantially the same and yet still differ.

[0038] It may be advantageous to use gears of essentially the same size to ensure the most even distribution and / or size of the required installation space. This can also be advantageous to avoid excessive differences in rotational speed, which can minimize existing forces and / or noise.

[0039] Furthermore, it can be provided within the scope of the invention that the number of teeth of the first gear, the second gear and / or the third gear differs, and / or the number of teeth of the first gear, the second gear and / or the third gear corresponds to a prime number.

[0040] Particularly preferably, the number of teeth of the first, second and / or third gear differs. This can be used to significantly expand the possible measuring range based on a vernier function. Due to the different number of teeth, it can be provided that during a full rotation (e.g. 360°) of one (e.g. first) gear, a gear (directly) coupled to it (e.g. second) does not complete a full rotation. Only after a few revolutions have been completed, e.g. a number resulting from the product of the number of teeth of one gear with the number of teeth of the other gear, can the two gears be in phase again. This allows the measuring position of the (associated) axis of rotation to be determined precisely, in particular unambiguously, over a large range.The fact that the third gear also differs from the others in terms of its number of teeth provides a further possibility (particularly analogous to the above description) for expanding the measuring range. In this case, it can advantageously be provided to precisely determine the position of the axes of rotation, and in particular of the lifting rod (coupled to the first axis of rotation), even at approximately 100 revolutions of a drive device (as described above). This preferably enables position determination over the entire range from the extreme steering angle to the left of the steering to the extreme steering angle to the right of the steering.

[0041] Alternatively or additionally, it can be provided that the number of teeth of the first gear, the second gear, and / or the third gear corresponds to a prime number. This can advantageously lead to the avoidance and / or reduction of the resulting noise (in particular noise). A prime number can only be divisible by itself and by the value 1. A gear that has a number of teeth that does not correspond to a prime number, e.g., 12 teeth, can exhibit different harmonics during operation (rotation). For example, the number 12 is divisible by the values ​​2, 3, 4, and 6 in addition to the values ​​1 and 12. This can therefore lead to different harmonics, which causes additional noise. This advantage can already be achieved if only one gear has a number of teeth corresponding to a prime number. For example, a first gear can have 31 teeth. The second gear can have 30 teeth.The third gear can have 33 teeth. The number of teeth would be essentially the same or not significantly different. Furthermore, the number of teeth on the first gear is 31, which corresponds to a prime number. This advantage can be increased if two or even three gears have a number of teeth corresponding to a prime number.

[0042] With regard to the present invention, it is conceivable that the first gear, the second gear and / or the third gear are manufactured in a lightweight construction and preferably comprise a plastic and / or that the first axis of rotation, the second axis of rotation and / or the third axis of rotation are manufactured in a lightweight construction and preferably comprise a plastic.

[0043] This can be advantageous in order to minimize and / or reduce the (overall) weight. This can be particularly preferred in combination with an optimized positioning of the measuring gear. By arranging it close to the drive device, and in particular not directly on the lifting rod, the forces acting on the measuring gear can be reduced. This can therefore be subjected to lower forces and is therefore more robust. In addition, this allows the use of materials to advantageously save weight, in particular without compromising robustness. Preferably, a plastic can be used. This can include, for example, polyamides. It can also be provided to use at least one of polyurethane (PUR), polyvinyl chloride (PVC) and / or acrylate butadiene styrene (ABS). The plastics can also and preferably be reinforced with glass fiber and / or carbon fiber.

[0044] Plastic can be lightweight, cost-effective, easy to manufacture, and / or quiet, especially compared to metal. Therefore, the combination of lightweight construction, especially plastic, and the use of a number of teeth for the first, second, and / or third gear that corresponds to a prime number may be particularly preferred. This allows noise to be reduced particularly efficiently.

[0045] The above object is further achieved by a method according to the invention for operating, in particular controlling and / or regulating, a steering actuator of a steer-by-wire system comprising:

[0046] - Providing a steering actuator with a measuring gear comprising a first axis of rotation, a second axis of rotation coupled thereto, and a third axis of rotation coupled to the first axis of rotation,

[0047] - detecting a first position of the first axis of rotation with a first sensor,

[0048] - detecting a second position of the second axis of rotation with a second sensor,

[0049] - Detecting a third position of the third rotation axis with a third sensor,

[0050] - Receiving the first position, the second position and the third position by a control unit,

[0051] - Calculating a first vernier function based on the first position and the second position to obtain a first result,

[0052] - Calculating a second vernier function based on the first position and the third position to obtain a second result,

[0053] - Calculating a third vernier function based on the first result and the second result to obtain a third result,

[0054] - Operating the steering actuator based on the third result. This results in the same advantages with respect to a method according to the invention as have already been described with respect to a steering actuator according to the invention.

[0055] The first vernier function can use the first position and the second position as input. According to the Vernier principle, a first length scale (here in particular the first position or angular position) can be used and related to a second length scale (here in particular the second position or angular position). The first result can have a (precise or more precise) determined, e.g. first, position. In other words, the position of the first rotational axis and / or the lifting rod can be determined here. The measuring range of the first rotational axis and / or the first gear is extended by using the vernier function with the second rotational axis and / or the second gear.

[0056] The same procedure can be followed for a second vernier function, using the first and third positions as input.

[0057] The same procedure can then be followed with a third vernier function. Since this uses the first and second results as input, this can also be referred to as a cascaded or nested vernier function in order to advantageously resolve position ambiguities. Cascading (further) expands the (unambiguously) determinable measuring range. This enables an accurate (in particular unambiguous) measurement of the first position and / or the position of a lifting rod, in particular over the entire range of motion of the lifting rod, for example over approximately 100 revolutions of a drive device. This can also be achieved when used with (in particular despite) a gear of the drive device. In other words, the position (or posture) of the lifting rod can be determined unambiguously and / or precisely based on (in particular exclusively based on) the first, second and / or third position.This allows the position to be determined independently of reference values. The accuracy is greater or at least comparable (e.g., 1 / 100) to known methods. Due to the structural design, a simpler, more cost-effective, and / or more space-saving device can be provided. The use of a control unit allows for precise coordination (e.g., with regard to hardware) with the device. Furthermore, other computing units (in the vehicle) can be relieved. The vernier functions themselves may not have any errors. Accordingly, the (measurement) error may be predetermined by the tolerances of the rotary axes and / or gears. It may therefore be provided, for the same (total) error, to use rotary axes and / or gears with a comparatively larger tolerance (e.g., 1 / 10 instead of 1 / 100). This can enable more cost-effective production.This can also allow the use of other materials, especially plastic. Overall, this can optimize, and in particular reduce, the weight and / or installation space.

[0058] Furthermore, it is conceivable that the third result comprises an actual position of a lifting rod for steering, wherein in particular an operation of the steering actuator based on the third result comprises an adjustment of the actual position of the lifting rod to a desired position.

[0059] The target position can be specified. This can be done, for example, by a driver using a steering wheel, particularly in steer-by-wire mode. This can be transmitted to the control unit, which then sets the actual position of the lifting rod, particularly by moving the lifting rod via a drive device. This can result in continuous determination of the position (or positions). The angle of the wheels can be continuously adjusted by the driver.

[0060] The above object is further achieved by a computer program product according to the invention, comprising instructions which, when the computer program product is executed by a computer, cause the computer to implement the method according to one of the preceding claims.

[0061] This results in the same advantages with regard to a computer program product according to the invention as have already been described with regard to a steering actuator according to the invention and / or a method according to the invention.

[0062] The above object is further achieved by a computer-readable data carrier according to the invention in which instructions are stored which, when executed by a computer, cause the computer to carry out the method according to one of the preceding claims.

[0063] This results in the same advantages with regard to a computer-readable data carrier according to the invention as have already been described with regard to a steering actuator according to the invention and / or a method according to the invention and / or a computer program product according to the invention.

[0064] The above object is further achieved by a control unit according to the invention, comprising a computing unit and a memory unit in which instructions are stored which, when at least partially executed by the computing unit, carry out a method according to one of the preceding claims.

[0065] The control unit can be integrated into the steering actuator. This can enable a particularly advantageous and / or compact design, which can significantly reduce costs.

[0066] In this case, a control unit can be used to receive the first position, the second position and the third position, wherein the control unit is designed: to calculate a first vernier function based on the first position and the second position in order to obtain a first result,

[0067] - to calculate a second vernier function based on the second position and the third position to obtain a second result,

[0068] - to calculate a third vernier function based on the first result and the second result to obtain a third result,

[0069] - to operate the steering actuator based on the third result.

[0070] Accordingly, the first, second and / or third result can be determined, in particular mathematically, by the control unit.

[0071] Furthermore, the control unit can be used to operate the steering actuator, in particular to control and / or regulate it. An external control signal, for example from another control unit and / or a steering wheel, can be received, in particular via a data connection. Based on this, the control unit can control the steering actuator via a data connection, for example to rotate the drive device in one direction or the other. Accordingly, the lifting rod can be moved or positioned. In other words, the control unit can be used to control the drive device, whereby it applies a torque and moves the lifting rod. A (desired) position can thus be approached.

[0072] The changed position can again be determined according to the invention, in particular in real time.

[0073] This results in the same advantages with respect to a control unit according to the invention as have already been described with respect to a steering actuator according to the invention and / or a method according to the invention and / or a computer program product according to the invention and / or a computer-readable data carrier according to the invention. The above object is further achieved by a vehicle according to the invention comprising a steering actuator and / or a control unit according to one of the preceding claims.

[0074] The vehicle can have a steer-by-wire system comprising a road wheel actuator (RWA, in particular for operating a lifting rod) and a hand wheel actuator (HWA, in particular comprising a decoupled steering wheel). The vehicle preferably has a lifting rod, via which the angle of the wheels can be adjusted. Accordingly, a movement, in particular a linear movement, e.g., in a right-left direction, of the lifting rod can lead to a changed steering angle. This allows the vehicle to be steered.

[0075] This results in the same advantages with respect to a vehicle according to the invention as have already been described with respect to a steering actuator according to the invention and / or a method according to the invention and / or a computer program product according to the invention and / or a computer-readable data carrier according to the invention and / or a control unit according to the invention.

[0076] Further advantages, features, and details of the invention will become apparent from the following description, in which several embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. In each case, schematically

[0077] Figure 1 a vehicle,

[0078] Figure 2 shows a vehicle or its steering actuator for a steer-by-wire system,

[0079] Figure 3 shows a steering actuator for a steer-by-wire system,

[0080] Figure 4 shows a method for operating a steering actuator of a steer-by-wire system, and Figure 5 shows an exemplary curve of the vernier functions.

[0081] In the following figures, identical reference numerals are used for the same technical features, even for different embodiments.

[0082] Fig. 1 shows a vehicle 200, for example a motor vehicle, which has a steering actuator 100. A steer-by-wire system can be implemented here. The steering angle of the wheels of the vehicle 200 can be adjusted via the steering actuator 100, for example on the front axle. The steering actuator 100 can have a control unit ECU and / or be connected to it for data communication. The control unit ECU can have a computing unit CU and a memory unit MU. To determine positions, in particular of the lifting rod and / or a first axis of rotation 11, the steering actuator 100 can have a measuring gear 10. This can be used for metrological purposes to enable ambiguities in the determination of the positions of rotationally symmetrical axes of rotation, for example behind a gear that connects a lifting rod and a drive device 40 (e.g., electric motor) for moving the lifting rod.

[0083] Fig. 2 shows an example or section of a vehicle 200. It depicts a lifting rod 201, at the ends of which wheels can be arranged, which can have a steering angle (adjustable by the lifting rod 201). A steering actuator 100 can be arranged on the lifting rod, which transmits a rotary movement of a drive device 40 (e.g., an electric motor) via a rotary shaft 41 to the lifting rod 201 in order to move it from left to right. A gear can be interposed. A measuring gear 10 can also be included in the steering actuator 100 in order to resolve the ambiguity of positions. For example, the rotary shaft 41 can correspond to a first axis of rotation 11. Also indicated (dashed) is a (data) connection to a steering wheel (shown above). Thus, overall, a steer-by-wire system can be implemented.

[0084] Fig. 3 shows, by way of example, a first gear 51, which is arranged centrally and has 31 teeth. The first gear 51 is centrally connected in a rotationally fixed manner to a first rotation axis 11. A first sensor 21 can determine the first position 31 of the first gear 51 and / or the first rotation axis 11.

[0085] Fig. 3 shows, by way of example, a second gear 52, which is arranged on the left and has 30 teeth. The second gear 52 is centrally connected in a rotationally fixed manner to a second rotational axis 12. A second sensor 22 can determine the second position 32 of the second gear 52 and / or the second rotational axis 12. The second gear 52 is toothed with the first gear 51, so that a rotational movement of the first gear 51 is transmitted to the second gear 52.

[0086] Fig. 3 shows, by way of example, a third gear 53, which is arranged on the right and has 33 teeth. The third gear 53 is centrally connected in a rotationally fixed manner to a third rotational axis 13. A third sensor 23 can determine the third position 33 of the third gear 53 and / or the third rotational axis 13. The third gear 53 is toothed with the first gear 51, so that a rotational movement of the first gear 51 is transmitted to the third gear 53.

[0087] Fig. 4 shows an example of a method for operating, in particular controlling and / or regulating, a steering actuator 100 of a steer-by-wire system comprising:

[0088] - Providing 110 a steering actuator 100 with a measuring gear 10 comprising a first rotational axis 11, a second rotational axis 12 coupled thereto, and a third rotational axis 13 coupled to the first rotational axis 11,

[0089] - detecting 121 a first position 31 of the first rotational axis 11 with a first sensor 21, - detecting 122 a second position 32 of the second rotational axis 12 with a second sensor 22,

[0090] - detecting 123 a third position 33 of the third rotation axis 13 with a third sensor 23,

[0091] - receiving 130 the first position 31, the second position 32 and the third position 33 by a control unit ECU,

[0092] - Calculating 141 a first vernier function N1 based on the first position 31 and the second position 32 to obtain a first result E1,

[0093] - Calculating 142 a second vernier function N2 based on the first position 31 and the third position 33 to obtain a second result E2,

[0094] - Calculating 143 a third vernier function N3 based on the first result E1 and the second result E2 to obtain a third result E3,

[0095] - Operating 150 the steering actuator 100 based on the third result E3.

[0096] By nesting the vernier functions, any ambiguity in the positions can be resolved. Advantageously, the third result E3 can be used to determine the exact position of a first rotational axis 11 and / or a lifting rod 201. Within the context of a steer-by-wire system, an actual position of the lifting rod 201 can thus be provided. Operation can include setting a (new) actual position based on a target position, which can be specified, for example, by a steering wheel.

[0097] Fig. 5 shows, by way of example, the course (or the results E1, E2, E3) of the first vernier function N1, the second vernier function N2 and the third vernier function N3. In this case, N1 and N2 are, for example, initially in phase (at the origin), and can therefore intersect at the origin. They then diverge over time t (x-axis corresponds to time, y-axis angle, e.g. up to 360°) until they intersect again at a later point in time after a few revolutions (e.g. 10 revolutions for N1 and 11 revolutions for N2) and, in particular, are in phase again. This can be the case, for example, if the first gear 51 has a total of 31 teeth, the second gear 52 has a total of 30 teeth and has a three-pole second sensor 22, and the third gear 52 has a total of 33 teeth and a three-pole sensor 23. The first vernier function N1 can resolve an ambiguity over 10 revolutions.The second vernier function N2 can resolve an ambiguity over 11 revolutions. Due to the cascading by the vernier function N3, the entire measuring range can thus be unambiguously extended to 10*11 = 110 revolutions.

[0098] A comparable curve would also result for the first position 31 and the second position 32 over time t (or analogously for the first position 31 and the third position 33). These are used as input for a first vernier function N1 to obtain the result E1. For example, the first position 31 and the second position 32 would initially be in phase (at the origin), i.e. they could intersect at the origin. They then diverge over time t until they intersect again at a later point in time after a few revolutions (e.g., 31 revolutions for the first position 31 or the first gear 51 and 10 revolutions for the second position 32 or the second gear 52) and, in particular, are in phase again. This can be the case, for example, if the first gear 51 has a total of 31 teeth and the second gear 52 has a total of 30 teeth and has a three-pole third sensor 22.

[0099] List of reference symbols

[0100] 10 measuring gears

[0101] 11 first axis of rotation

[0102] 12 second axis of rotation

[0103] 13 third axis of rotation

[0104] 21 first sensor

[0105] 22 second sensor

[0106] 23 third sensor

[0107] 31 first position

[0108] 32 second position

[0109] 33 third position

[0110] 40 Drive device

[0111] 41 Rotating shaft

[0112] 51 first gear

[0113] 52 second gear

[0114] 53 third gear

[0115] 100 steering actuator

[0116] 110 Providing a steering actuator

[0117] 121 Recording a first position

[0118] 122 Recording a second position

[0119] 123 Recording a third position

[0120] 130 Receiving the first, second and third position

[0121] 141 Calculate a first vernier function N1 to obtain E1

[0122] 142 Calculate a second vernier function N2 to obtain E2

[0123] 143 Calculate a third vernier function N3 to obtain E3

[0124] 150 Operating the steering actuator based on E3

[0125] E1 first result

[0126] E2 second result

[0127] E3 third result

[0128] N1 first vernier function N2 second vernier function

[0129] N3 third vernier function

[0130] 200 vehicles

[0131] 201 lifting rod

[0132] ECU control unit

[0133] CU computing unit

[0134] MU storage unit

Claims

Patent claims 1 . Steering actuator (100) for a steer-by-wire system for determining a position of a lifting rod (201) for steering, comprising: - a measuring gear (10) with a first axis of rotation (11), a second axis of rotation (12) coupled to the first axis of rotation (11), and a third axis of rotation (13) coupled to the first axis of rotation (11), - a first sensor (21) for detecting a first position (31) of the first axis of rotation (11), - a second sensor (22) for detecting a second position (32) of the second axis of rotation (12), - a third sensor (23) for detecting a third position (33) of the third axis of rotation (13), - a control unit (ECU) for receiving the first position (31), the second position (32) and the third position (33), wherein the control unit (ECU) is designed: o to calculate a first vernier function (N1) based on the first position (31) and the second position (32) in order to obtain a first result (E1), o to calculate a second vernier function (N2) based on the first position (31) and the third position (33) in order to obtain a second result (E2), o to calculate a third vernier function (N3) based on the first result (E1) and the second result (E2) in order to obtain a third result (E3), o to operate the steering actuator (100) based on the third result (E3).

2. Steering actuator (100) according to claim 1, characterized in that the steering actuator (100) has a drive device (40), in particular an electric motor (40), for driving the lifting rod (201) for steering, wherein preferably a rotary shaft (41) of the drive device (40) substantially coincides with the first axis of rotation (11), in particular is identical.

3. Steering actuator (100) according to one of the preceding claims, characterized in that the first sensor (21), the second sensor (22) and / or the third sensor (23) are designed as multi-pole sensors, wherein these in particular provide at least two periods over a full revolution.

4. Steering actuator (100) according to one of the preceding claims, characterized in that the first sensor (21) can be arranged on or in the first axis of rotation (11), the second sensor (22) can be arranged on or in the second axis of rotation (12), and / or the third sensor (23) can be arranged on or in the third axis of rotation (13), wherein preferably the axes of rotation (11, 12, 13), sensors (21, 22, 23) and / or the control unit (ECU) are compactly integrated in the steering actuator (100).

5. Steering actuator (100) according to one of the preceding claims, characterized in that the first axis of rotation (11) has a first gear (51), which can be arranged in particular centrally, wherein the second axis of rotation (12) has a second gear (52) which can be coupled to the first gear (51) in a toothed manner, and wherein the third axis of rotation (13) has a third gear (53) which can be coupled to the first gear (51) in a toothed manner.

6. Steering actuator (100) according to one of the preceding claims, characterized in that the measuring gear (10) has a spur gear.

7. Steering actuator (100) according to one of the preceding claims, characterized in that the first gear (51), the second gear (52) and / or the third gear (53) have substantially the same size and / or the same number of teeth.

8. Steering actuator (100) according to one of the preceding claims, characterized in that the number of teeth of the first gear (51), the second gear (52) and / or the third gear (53) differ, and / or wherein the number of teeth of the first gear (51), the second gear (52) and / or the third gear (53) corresponds to a prime number.

9. Steering actuator (100) according to one of the preceding claims, characterized in that the first gear (51), the second gear (52) and / or the third gear (53) are manufactured in a lightweight construction and preferably comprise a plastic, and / or that the first axis of rotation (11), the second axis of rotation (12) and / or the third axis of rotation (13) are manufactured in a lightweight construction and preferably comprise a plastic.

10. Method for operating, in particular controlling and / or regulating, a steering actuator (100) of a steer-by-wire system comprising: - Providing (110) a steering actuator (100) with a measuring gear (10) comprising a first axis of rotation (11), a second axis of rotation (12) coupled thereto, and a third axis of rotation (13) coupled to the first axis of rotation (11), - detecting (121) a first position (31) of the first axis of rotation (11) with a first sensor (21), - detecting (122) a second position (32) of the second axis of rotation (12) with a second sensor (22), - detecting (123) a third position (33) of the third axis of rotation (13) with a third sensor (23), - receiving (130) the first position (31), the second position (32) and the third position (33) by a control unit (ECU), - calculating (141) a first vernier function (N1) based on the first position (31) and the second position (32) to obtain a first result (E1), - calculating (142) a second vernier function (N2) based on the first position (31) and the third position (33) to obtain a second result (E2), - calculating (143) a third vernier function (N3) based on the first result (E1) and the second result (E2) to obtain a third result (E3), - Operating (150) the steering actuator (100) based on the third result (E3).

11. Method according to claim 10, characterized in that the third result (E3) comprises an actual position of a lifting rod (201) for steering, wherein in particular an operation of the steering actuator (100) based on the third result (E3) comprises an adjustment of the actual position of the lifting rod (201) to a desired position.

12. A computer program product comprising instructions which, when the computer program product is executed by a computer, cause the computer to implement the method according to any one of the preceding claims.

13. A computer-readable data carrier in which instructions are stored which, when executed by a computer, cause the computer to carry out the method according to one of the preceding claims.

14. Control unit (ECU), comprising a computing unit (CU) and a memory unit (MU) in which instructions are stored which, when at least partially executed by the computing unit (CU), carry out a method according to one of the preceding claims.

15. Vehicle (200) comprising a steering actuator (100) and / or a control unit (ECU) according to one of the preceding claims.

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