Method for operating an adjustable roll stabilizer

Abstract

A method for operating an adjustable roll stabilizer (1) for a motor vehicle, wherein the adjustable roll stabilizer (1) has an actuator (2) which is rotatable about a rotation axis (3) by a system angle (α) in order to rotate two stabilizer sections (6a, 6b) connected thereto about the rotation axis (3) relative to each other, wherein the stabilizer sections (6a, 6b) are each coupled to a wheel suspension (7a, 7b, 8a, 8b, 9a, 9b) radially from the rotation axis (3), wherein a field-oriented controller (20) controls the actuator (2) depending on input signals comprising at least one target motor torque (21), characterized in that the control of the actuator (2) initiated by the field-oriented controller (20) is checked for plausibility independently of the field-oriented controller (20), wherein the check for Plausibility is essentially based on a comparison of the engine's target torque (21) with the engine's actual torque (22).

Description

[0001] The invention relates to a method for operating an adjustable roll stabilizer for a motor vehicle according to claim 1 and a roll stabilization system according to claim 8.

[0002] In automotive engineering, particularly chassis engineering, it is known to influence the roll and pitch behavior of vehicles using so-called roll stabilizers. The basic design consists of an essentially C-shaped torsion bar spring, which is rotatably mounted in the middle relative to the vehicle body. Its outer, opposing ends are connected to a wheel suspension via coupling elements, known as pendulum links. This design ensures that, when cornering, the vehicle body not only compresses on the outside side (due to centrifugal force), but also that the inside wheel is slightly lowered. Roll stabilizers improve the vehicle's directional stability and reduce body roll, thus making cornering safer and more comfortable.

[0003] To further enhance vehicle stability and ride comfort, it is known to design such roll stabilizers to be adjustable. In this case, the roll stabilizer comprises an actuator and is divided into two stabilizer sections that can be rotated relative to each other about an axis of rotation by means of the actuator. By rotating the stabilizer sections relative to each other, a roll movement of the vehicle body is deliberately generated, or a roll movement of the vehicle body caused by external influences is deliberately counteracted. Adjustable roll stabilizers are known from the prior art, the actuator of which has an electric motor that is connected to a mechanical transmission, in particular in the form of a multi-stage planetary gear unit, to achieve suitable speeds or torques. In this context, reference is made to DE 10 2016 219 399 A1 by way of example.

[0004] Besides the constructive design of an adjustable roll stabilizer, its appropriate control also presents a technical challenge.

[0005] The appropriate control of the actuator of an adjustable roll stabilizer requires various preliminary considerations of varying complexity, from which a suitable control strategy for the adjustable roll stabilizer or the vehicle equipped with it can be developed. Within the scope of this invention, such preliminary considerations or the control strategies that can be developed from them will not be discussed in detail; rather, the control of the actuator itself will be considered. According to one desired embodiment, the actuator, in particular a motor of the actuator, is controlled by means of a field-oriented controller. Its function can be to implement a target motor torque specified by upstream control instances by appropriately controlling the actuator. The field-oriented controller receives, as input variables, not only a target motor torque to be set, but also the current motor position and, if applicable, other parameters.further operating parameters of the adjustable roll stabilizer and / or the vehicle equipped with it, in order to control the actuator on this basis.

[0006] Since an adjustable roll stabilizer is a chassis system relevant to vehicle safety, there is a need to be able to check and monitor the correctness of the previously described control of the actuator's motor by the field-oriented controller. This is because adverse effects of faulty control can include, for example, understeer or oversteer, or excessive body roll.

[0007] A method according to the features of the preamble of the claim is known from DE 10 2014 203 388 A1. However, the method does not include a verification of the correctness of the control of the actuator's motor as described therein.

[0008] Viewed in isolation, DE 10 2017 202 954 A1 reveals the idea of ​​using the values ​​for the stabilizer moment, determined in various ways, to mutually monitor the correctness (plausibility check) of different modules.

[0009] It is an object of the present invention to provide a method for operating an adjustable roll stabilizer for a motor vehicle, which offers the possibility of detecting a faulty control of the actuator in a timely manner and thus preventing adverse driving behavior of the motor vehicle equipped with the adjustable roll stabilizer. Furthermore, a roll stabilization system that solves the aforementioned problem is to be provided.

[0010] The aforementioned problem is initially solved by a method according to the features of claim 1. This method is for operating an adjustable roll stabilizer for a motor vehicle, wherein the adjustable roll stabilizer has an actuator that is rotatable about a system angle with respect to an axis of rotation in order to rotate two stabilizer sections connected thereto about the axis of rotation relative to each other. The stabilizer sections are each coupled to a wheel suspension radially from the axis of rotation. According to the invention, a field-oriented controller controls the actuator depending on input signals comprising at least one target motor torque, wherein the control of the actuator initiated by the field-oriented controller is checked for plausibility independently of the field-oriented controller, and wherein the plausibility check is essentially based on a comparison of the target motor torque with an actual motor torque.

[0011] According to the invention, it was first recognized that, due to the safety relevance of an adjustable roll stabilizer for the equipped vehicle, a faulty control of the actuator can lead to a deterioration of the handling characteristics, or at least a reduction in ride comfort. Faulty control can result in oversteer or understeer, as well as excessive roll angles of the vehicle. To avoid such disadvantages, it was considered advantageous to independently check the plausibility of the actuator's field-oriented controller with regard to its control of the actuator. This check is more of a rough assessment to determine whether the control is plausible at all, i.e., not obviously incorrect, than a precise verification of its correctness. The plausibility check is thus performed with the aim of preventing obviously incorrect control signals.

[0012] According to the invention, the plausibility check is essentially based on a comparison of the motor's target torque with its actual torque. Advantageously, the actual torque can be calculated from the motor phase currents of the motor (or actuator). It is shown that a relatively accurate calculation of the actual torque is possible after only a relatively brief analysis of the motor phase currents.

[0013] As previously explained, the plausibility check is essentially based on a comparison of the target engine torque with the actual engine torque. According to a preferred embodiment of the method, the plausibility check is preferably carried out by placing a positive tolerance band (upper tolerance) and a negative tolerance band (lower tolerance) around the target engine torque and comparing the actual engine torque with the target engine torque. If both conditions are met—that the actual engine torque is above the lower tolerance and that the actual engine torque is below the upper tolerance—the target engine torque is considered plausible.

[0014] According to a further advantageous embodiment of the method, the height of the tolerance band is derived from a permissible deviation, particularly at the level of the vehicle, for a torque applied by the adjustable roll stabilizer, expediently converted into a torque attributable to the engine. In other words, the tolerance band above and below the engine's nominal torque corresponds to the permissible torque deviation of the adjustable roll stabilizer, which is specified at the level of the vehicle.

[0015] A suitable design of the described procedure provides that a time delay is taken into account in the comparison between actual engine torque and target engine torque carried out as part of the plausibility check.

[0016] The motor target torque used within the scope of the invention, particularly for plausibility testing, is advantageously a quantity that is specified by a controller upstream and / or superior to the field-oriented controller, in particular a position-speed controller.

[0017] In the preceding description, the term "control of the actuator" has been used generally. However, since the actuator of the adjustable roll stabilizer advantageously comprises an electric motor, within the scope of this invention, "control of the actuator" should also be understood more narrowly as the control of a motor associated with the actuator.

[0018] The aforementioned problem is also solved by a roll stabilization system according to claim 8. This is a roll stabilization system configured to perform a method of the type described above.

[0019] The invention is explained in more detail below with reference to a drawing. Further advantageous embodiments of the invention also become apparent from this drawing. The drawing shows: Fig. 1. An adjustable roll stabilizer for a motor vehicle in schematic view, Fig. 2 a graphical representation of a control strategy of an adjustable roll stabilizer, Fig. 3 a schematic representation of a field-oriented motor control, Fig. 4 a schematic representation of a plausibility check of the engine's target torque, Fig. 5 a graphical representation of a plausibility scheme according to an embodiment of the invention.

[0020] To illustrate the field of application of the invention, the following is shown: Fig. Figure 1 shows a schematic view of an adjustable roll stabilizer 1. The adjustable roll stabilizer 1 is part of the chassis of a (not shown) motor vehicle, which is not fully depicted. Only the vehicle body 10 is indicated by reference numerals. The roll stabilizer 1 is also part of an axle of the motor vehicle; for example, the front axle and / or rear axle of the motor vehicle may be equipped with the adjustable roll stabilizer 1.

[0021] How Fig. As shown in Figure 1, a left wheel 7a and a right wheel 7b located on the opposite side of the vehicle are each connected to the vehicle body 10 via a linkage assembly 8a and 8b, respectively, which will not be explained in detail. Wheel 7a and linkage assembly 8a, and wheel 7b and linkage assembly 8b, thus each form a unit and are each coupled to an end of a corresponding stabilizer section 6a and 6b of the adjustable roll stabilizer 1 via a pendulum support 9a and 9b, respectively. The left stabilizer section 6a and the right stabilizer section 6b are connected to each other at the center of the vehicle via an actuator 2, which is depicted as a substantially cylindrical body.

[0022] In a manner known in itself, the adjustable roll stabilizer 1 is rotatably mounted about a rotational axis 3 relative to the vehicle body 10; for this purpose, a left stabilizer mounting 11a and a right stabilizer mounting 11b are used, which according to Fig. 1. Enclose a U-shaped area of ​​the respective stabilizer section 6a or 6b facing the actuator 2 - simplified representation.

[0023] The actuator 2, depicted here as a cylindrical body, essentially comprises a housing (not further specified) that is substantially rotationally symmetrical with respect to the axis of rotation 3. An electric motor 4, a multi-stage planetary gear 5, and a speed sensor 13 (each indicated only by reference numerals) are arranged within this housing. The stabilizer sections 6a and 6b are connected to each other via the electric motor 4 and the multi-stage planetary gear 5. When the actuator 2 is stationary, the two stabilizer sections 6a and 6b are rigidly connected to each other via the stationary electric motor 4 and the multi-stage planetary gear 5 connected to it. However, the operation of the electric motor 4 allows the stabilizer sections 6a and 6b to be rotated relative to each other about the axis of rotation 3, depending on the direction of rotation of the electric motor 4.The multi-stage planetary gear 5 provides a fixed speed ratio between the input (electric motor 4) and the output (right stabilizer section 6b coupled to the gear output). This allows the adjustable roll stabilizer 1 to be adjusted in a manner known from its own perspective.

[0024] Depending on the operating state of the adjustable roll stabilizer 1 or the vehicle equipped with it, a torsion can occur in the stabilizer sections 6a, 6b coupled to each other via the actuator 2, depending on which a moment M acting about the axis of rotation 3 System developed. This moment M System The signal is present at actuator 2 in the form of a system moment.

[0025] With the help of the roll stabilizer 1, a roll moment M can be reduced. Wank The roll moment M is supported between the vehicle body 10 and the wheels 7a, 7b. The roll moment M that can be supported can be adjusted by adjusting the roll stabilizer 1. WankTo influence the roll stabilizer 1 as needed, a height sensor 12a is assigned to the left wheel 7a and a height sensor 12b to the right wheel 7b, respectively. These sensors detect wheel travel movements of the respective wheels and output them as a height value z7a for the left wheel and z7b for the right wheel. Additionally, the rotation of the electric motor 4 can be detected via the speed sensor 13 and output as a speed signal, i.e., the motor speed n.

[0026] The regulation of the in Fig. 1. The adjustable roll stabilizer 1, shown schematically, is based on the in Fig. The control strategy shown in Figure 2 is explained in more detail below. Accordingly, the control of the adjustable roll stabilizer 1 uses a so-called system setpoint torque as an input variable. This is a value specified by the vehicle, which corresponds to the torque M acting about the axis of rotation 3. System (cf.) Fig. 1) corresponds to the moment of roll that is to be supported by the adjustable roll stabilizer 1 at the level of the actuator, which therefore acts on the actuator 2 – comprising electric motor 4 and gearbox 5 – with a direction of rotation about the axis of rotation 3. Through the kinematic interaction of the adjustable roll stabilizer 1, the wheel suspensions 7a, 7b, 8a, 8b, 9a, 9b and the connections 11a, 11b to the vehicle body 10, the adjustable roll stabilizer 1 thus supports – at the level of the vehicle – an axle-related roll moment M. Wank from (see above) Fig. 1, running along the longitudinal direction of the vehicle).

[0027] The system target torque is converted into a twist angle for the torque requirement via a known system stiffness, whereby the known system stiffness is composed of individual stiffnesses, in particular the stiffnesses of the stabilizer itself (stabilizer sections, gearbox, housing, possibly decoupling elements, pendulum support, stabilizer bearing and the like).

[0028] In parallel, a parameter for compensating for disturbances is incorporated into the control system of the adjustable roll stabilizer. This involves using wheel movement data, recorded by wheel height sensors in the form of individual wheel height signals, as well as a characteristic table for a decoupling angle (using previously determined vehicle-specific data) to determine a so-called "zero-torque angle." This angle corresponds to the external rotation angle of the adjustable roll stabilizer, caused, for example, by an uneven road surface, and would render the actuator of the adjustable roll stabilizer torque-free. The two angles determined in this way—the rotation angle for the torque request and the zero-torque angle—are then added to obtain a target angle.

[0029] The target angle is then fed to a cascaded position-speed controller. This includes a position controller which, based on the incoming target angle and taking into account a feedback signal from the motor, determines a target speed. This target speed is then fed into a speed controller. Based on the target speed and feedback from the electric motor (speed), the speed controller determines a target torque for controlling the electric motor.

[0030] The target motor torque is fed back to a field-oriented control system, which – again taking into account feedback signals from the electric motor – controls the electric motor 4 of the actuator 2. A motor output torque generated by the electric motor 4 is converted – now mechanically – via a gearbox 5 (multi-stage planetary gearbox) into a system torque, which is applied between the stabilizer sections (cf. Fig. 1 Reference numerals 6a and 6b) apply.

[0031] The in Fig. The control scheme shown in section 2 is advantageously applied to a system like the one in Fig. 1. Adjustable roll stabilizer shown. In the control principle described therein, an incoming system target torque is converted into a target angle via the system stiffness, from which a motor target torque is determined by means of a position-speed controller, whereby the motor is supplied with corresponding motor currents.

[0032] For further explanation of the invention, reference is now made to Fig. 3. This schematically represents a field-oriented motor control. The field-oriented motor control 20, indicated as a rectangle, is part of the already described above. Fig. 2. Control concept of an adjustable roll stabilizer as shown and explained in Figure 2. Fig. 1 shown.

[0033] The field-oriented control system 20 receives input signals including a target motor torque 21, a motor position 24 (feedback from motor 4), and various parameters 25. Depending on these input signals, the field-oriented motor control system 20 outputs signals 31, 32, and 33, which are used to control the (in Fig. 3 (not shown) Motor 4 of actuator 2 (see Fig. 2 or Fig. 1) is controlled. Preferably, these are pulse-width modulated target phases 1, 2 and 3 for controlling the motor 4. Accordingly, the motor 4 of the actuator 2 is controlled by means of the field-oriented control 20 depending on the aforementioned input signals.

[0034] In operational use, for various reasons, the field-oriented control 20 may cause the actuator (motor 4) to be controlled incorrectly based on the input signals. However, incorrect actuator control can easily lead to disadvantages regarding the driving comfort and / or driving safety of the vehicle equipped with the adjustable roll stabilizer. Among other things, it can result in understeer or oversteer of the vehicle, or in inappropriately large roll angles.

[0035] Therefore, within the scope of the invention, a plausibility check of the actuator control is provided – independent of the field-oriented controller 20. In this context, it should first be noted that Fig. Reference is made to Figure 4, which schematically illustrates a plausibility check of the motor target torque. Accordingly, monitoring by the field-oriented control 23 ensures that the actuator control initiated by the field-oriented controller 20 is checked for plausibility independently of the field-oriented controller 20. This plausibility check is essentially based on a comparison of the motor target torque with the actual motor torque, for which the motor target torque 21 and the actual motor torque 22 are used as input variables in the monitoring system 23. The output variable of the monitoring system 23 is any detected error 26, which is displayed if the plausibility check fails. The plausibility check itself will be described in more detail in Figure 4. Fig. 5 explained.

[0036] Fig. Figure 5 shows a graphical representation of a plausibility check scheme used according to a preferred embodiment of the invention. The input variables shown in the left part of the image are the target motor torque 21 and the actual motor torque 22. The latter is expediently derived from the motor phase currents of the motor 4 of the actuator 2 (see Figure 5). Fig. 1 and Fig. 2) calculated. The target motor torque 21 is delayed ("buffered") in time to achieve temporal synchronization between the target motor torque 21 and the actual motor torque 22. The temporal buffering is in Fig. 5 is not shown in the drawing for the sake of simplicity.

[0037] The plausibility check of the target motor torque 21 is performed by applying a positive tolerance band and a negative tolerance band around the target motor torque 21 and then comparing the actual motor torque 22 with the target motor torque 21. For this purpose, an upper tolerance in the form of an upper threshold value 27 is first added to the target motor torque 21, and a lower tolerance in the form of a lower threshold value 28 is subtracted from the target motor torque 21. The actual motor torque 22 is then compared against both the upper and lower tolerances, whereby the Fig. The AND operation shown in the middle ensures that plausibility exists only if the motor torque 22 is above the lower tolerance and below the upper tolerance.

[0038] A reverse logic gate (“NOT”), combined with subsequent time-based debouncing, ensures that if one of the two comparison criteria is not met for a certain debouncing time, an error 26 is output, indicating a lack of plausibility in the actuator control by the field-oriented controller. This lack of plausibility can point to various causes of the error, including defective motor phases of motor 4, faults in the power electronics, or errors in the software of the field-oriented controller 20 itself. Reference sign 1 adjustable roll stabilizer 2 Actuator 3 4 Rotation axis electric motor 5 multi-stage planetary gear 6a, 6b left (or right) stabilizer section 7a, 7b left (or right) wheel 8a, 8b left (or right) handlebar arrangement 9a, 9b left (or right) pendulum support 10 Vehicle body 11a, 11b left (or right) stabilizer bearing 12a, 12b Height sensor left (or right) wheel 13 Speed ​​sensor 20 field-oriented (motor) control 21 Motor torque 22 Engine torque 23 Monitoring field-oriented control 24 engine positions 25 assorted sizes 26 errors 27 upper threshold 28 lower threshold 29 Time-based debouncing 31 pulse-width modulated target phase 1 32 pulse-width modulated target phase 2 33 pulse-width modulated target phase 3 z7a, z7b Height of left (or right) wheel M Wank Rolling moment (axis-related) M System System moment n engine speed α System angle

Claims

[1] Method for operating an adjustable roll stabilizer (1) for a motor vehicle, wherein the adjustable roll stabilizer (1) has an actuator (2) which is rotatable about a rotation axis (3) by a system angle (α) in order to rotate two stabilizer sections (6a, 6b) connected thereto about the rotation axis (3) relative to each other, wherein the stabilizer sections (6a, 6b) are each coupled to a wheel suspension (7a, 7b, 8a, 8b, 9a, 9b) radially from the rotation axis (3), wherein a field-oriented controller (20) controls the actuator (2) depending on input signals comprising at least one target motor torque (21), characterized by , that the control of the actuator (2) initiated by the field-oriented controller (20) is checked for plausibility independently of the field-oriented controller (20), the plausibility check being based essentially on a comparison of the motor set torque (21) with a motor actual torque (22). [2] Method according to claim 1, characterized by , that the motor torque (22) is calculated from the motor phase currents of the motor (4). [3] Method according to any of the preceding claims, characterized by , that the plausibility check is carried out in such a way that a positive tolerance band (27) and a negative tolerance band (28) are placed around the motor target torque (21) and the motor actual torque (22) is compared with the motor target torque (21), whereby if both conditions are met, that the motor actual torque (22) is above the lower tolerance and the motor actual torque (22) is below the upper tolerance, the motor target torque (21) is to be considered plausible. [4] Method according to claim 3, characterized by , that the height of the tolerance band is determined by a permissible deviation, particularly at the level of the vehicle, for a moment (M) applied by the adjustable roll stabilizer (1). Wank) results, expediently converted to a torque attributable to the motor (4). [5] Method according to any of the preceding claims , characterized by , that a time delay (29) is taken into account in the comparison between actual motor torque (22) and target motor torque (21) carried out as part of the plausibility check. [6] Method according to any of the preceding claims, characterized by , that the motor target torque (21) is specified by a controller upstream and / or superior to the field-oriented controller (20), in particular a position-speed controller. [7] Method according to any of the preceding claims, characterized by , that controlling the actuator (2) is to be understood as controlling a motor (4) associated with the actuator (2). [8] System for roll stabilization suitable for carrying out a method according to any of the preceding claims.

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