Method for operating an adjustable roll stabilizer

Abstract

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 position-speed controller is set from a target angle (α) to be set on the actuator (2). Soll ) and taking into account the actual system angle (α) as well as other parameters (21, 22) of the roll stabilizer (1) and / or the motor vehicle equipped with it, a target motor torque (23) is determined, on the basis of which a motor (4) of the actuator (2) is controlled, taking into account the target angle (α) Soll) and the actual system angle (α) a plausibility check of the motor target torque (23) is carried out.

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 10.

[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 actuator, including the electric motor, of an adjustable roll stabilizer is operated in both directions during normal vehicle use to fulfill its function as described above. In one possible configuration, a position-speed controller can be provided, which, among other things, determines a target motor torque based on a set target angle. This target torque then controls the actuator's electric motor. Depending on the operating conditions of the adjustable roll stabilizer, the target motor torque determined by the position-speed controller can point in either of the two possible directions of rotation.

[0006] Within the adjustable roll stabilizer, particularly in the stabilizer sections, mechanical energy (kinetic energy or potential energy generated by deformation) can be stored, depending on the operating conditions. During actuator operation, based on a target motor torque determined by the position-speed controller from a set angle, the stored mechanical energy within the adjustable roll stabilizer can cause more or less pronounced overshoots between the actual motor position and the target motor position. In other words, the mechanical energy stored within the adjustable roll stabilizer under certain operating conditions is then transferred to the actuator motor via the mechanical coupling (gearbox).This can lead to a situation where, instead of a gradual approach between the actual and target motor positions, the actual motor position "overtakes" the target motor position. In such cases, it is advantageous—deviating from a conventional control principle—to brake the actuator motor before it reaches its target position, i.e., to output a target motor torque in the opposite direction. For this purpose, the motor of an adjustable roll stabilizer is advantageous—depending on the operating conditions—to operate not only driving in both directions but also decelerating (braking) in both directions, i.e., in a so-called four-quadrant operation.

[0007] A comparable braking behavior may be required in the case of an external force being introduced from the wheel mounting points to the adjustable roll stabilizer, for example due to uneven road surfaces, if the externally acting force on the engine produces a torque in the correct direction to reduce the existing control deviation.

[0008] DE 10 2013 110 953 A1 discloses a method for operating an adjustable roll stabilizer. Starting from a target angle to be set on the actuator and taking into account the actual system angle as well as other parameters, a target motor torque is determined by means of a position-speed controller, on the basis of which the motor of the actuator is controlled.

[0009] It is an object of the present invention to provide a method for operating an adjustable roll stabilizer in which, within the framework of position-speed control, the possibility is created to reliably operate the actuator's motor in both directions of rotation, both driving and decelerating (four-quadrant operation). In addition, a corresponding roll stabilization system is to be provided.

[0010] The 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. A position-speed controller determines a target motor torque based on a setpoint angle to be adjusted on the actuator and taking into account the actual system angle as well as other parameters of the roll stabilizer and / or the motor vehicle equipped therewith, on the basis of which a motor of the actuator is controlled.According to the invention, a plausibility check of the motor target torque is carried out taking into account the target angle and the actual system angle.

[0011] According to the invention, it was first recognized that, within an adjustable roll stabilizer, stored mechanical energy, particularly in the stabilizer sections, can cause the actuator motor to overshoot due to mechanical coupling. Furthermore, external forces, such as those caused by uneven road surfaces, can have a feedback effect on the actuator motor, making braking the motor advantageous in both cases (overshoot and external force application). The invention proposes a plausibility check of the target motor torque determined by the position-speed controller, taking into account the target angle and the actual system angle.

[0012] Advantageously, the plausibility check is performed by examining the control deviation between the target angle and the system angle. Within the scope of the invention, the target angle is understood to be the system angle to be set at the actuator. This is the angle by which the two stabilizer sections connected to the actuator are to rotate relative to each other about the axis of rotation. The target angle can, for example, be specified by an upstream control instance.

[0013] For the desired four-quadrant operation of the actuator's electric motor, it is advisable to perform a plausibility check of the target torque determined by the position-speed controller. This is advantageously done based on at least two criteria, namely whether: the control deviation between the target angle and the system angle increases, and The motor target torque exhibits a direction that increases the control deviation, and if both criteria are met, the plausibility check will fail. In other words, if an operating condition exists in which both the control deviation between the target angle and the system angle increases, and the motor target torque also exhibits a direction that increases the control deviation, the motor target torque determined by the position-speed controller is not plausible.

[0014] Additionally or alternatively, according to an advantageous embodiment of the method, the plausibility check is positive at least if the motor target torque contributes to a reduction of the control difference between target angle and actual system angle.

[0015] In principle, the proposed plausibility check can be performed during the operation of the adjustable roll stabilizer. However, a more suitable refinement of the procedure stipulates that the plausibility check described above is only carried out if a threshold value, which can be parameterized, of the target engine torque and / or the control deviation is exceeded.

[0016] According to the invention, the position-speed controller determines the target motor torque based on a target angle set at the actuator and taking into account the actual system angle as well as other parameters of the roll stabilizer and / or the vehicle equipped with it. It is advantageous that at least one of the other parameters considered is the vehicle speed of the vehicle equipped with the adjustable roll stabilizer.

[0017] The actuator's motor is controlled based on the target motor torque determined by the position-speed controller. Advantageously, this is achieved by feeding the determined target motor torque for the actuator to a field-oriented control system, which in turn controls a motor assigned to the actuator.

[0018] As described, the target angle to be set at the actuator is entered as an input variable into the position-speed controller used for the process. According to an advantageous embodiment of the process, this angle is determined taking into account a reference variable and a disturbance-compensating variable. This is expediently carried out in an upstream controller instance.

[0019] An advantageous embodiment of the method provides that the reference variable is a rotation angle for a vehicle-side torque request (in particular determined by multiplication with the reciprocal of the system stiffness). The disturbance-compensating variable is preferably a zero-torque angle (actuator angle at which it is torque-free, taking into account the current wheel heights), wherein the rotation angle for the torque request and the zero-torque angle are added to the target angle to be set on the actuator.

[0020] The aforementioned problem is also solved by a roll stabilization system according to claim 10. This is a roll stabilization system configured to perform a method of the type described above.

[0021] 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 position-speed controller together with a schematic representation of a plausibility function, Fig. 4 a graphical representation of a plausibility scheme according to an embodiment of the invention.

[0022] 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.

[0023] 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 7a and 7b 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.

[0024] 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.

[0025] 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 9, 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.

[0026] 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.

[0027] 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.

[0028] 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).

[0029] The system's target torque is converted into a rotation angle for the torque request via a known system stiffness. This known system stiffness is composed of individual stiffnesses, particularly the stiffnesses of the stabilizer itself (stabilizer sections, gearbox, housing, decoupling elements if applicable, pendulum support, stabilizer bearings, and the like). In parallel, a parameter for compensating for disturbances is incorporated into the control of the adjustable roll stabilizer. For this purpose, wheel movement data, acquired by wheel-specific height sensors, is used in the form of height signals (for each wheel), along with a characteristic value 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—namely, the rotation angle for the torque request and the zero-torque angle—are then added to obtain a target angle.

[0030] The target angle is then fed to a cascaded position-speed controller. This includes a position controller which, from the incoming target angle and taking into account a feedback signal from the motor, determines a target speed, which in turn is fed to a speed controller. Based on the target speed and feedback from the electric motor (speed), the speed controller determines a target motor torque for controlling the electric motor. The target motor torque is then fed 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 gear unit) into a system torque, which is applied between the stabilizer sections (see Figure 1). 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 shows a schematic representation of a position-speed controller along with a schematic representation of a plausibility function. The position-speed controller, shown there as a rectangle labeled 26 for a position-speed cascade (SPC), is advantageously used within a system as described above. Fig. 2. The control strategy of an adjustable roll stabilizer is explained. In addition to the position-speed cascade 26, it shows Fig. 3 schematically a quadrant monitoring 27 of the position-rotation cascade, also shown as a rectangle (label 27).

[0033] Various input signals are fed into the position-speed cascade 26, which are processed into an output signal in the form of a motor setpoint torque 23. The motor setpoint torque 23 represents the output of the position-speed controller. The outgoing motor setpoint torque 23 is – as shown by… Fig. 2 already explained - fed into a field-oriented control 25, which ultimately allows the control of the actuator's motor.

[0034] The input variables of the position-speed cascade 26 are the system angle α (actual actuator angle or "actual angle"), the target angle α Soll(actuator angle to be set), a vehicle speed 22 (of the motor vehicle equipped with the roll stabilizer 1), and possibly various other parameters 21 (for example, a steering angle of the motor vehicle or the like). The basic function of the position-speed cascade 26 shown is to, starting from a target angle α to be set on the actuator, Soll and taking into account the actual system angle α as well as other parameters of the motor vehicle such as the vehicle speed 22 and, for example, the steering angle, to determine the motor target torque 23, on the basis of which the motor of the actuator can be controlled.

[0035] In certain operating situations, it may be necessary to brake the actuator motor. Such a situation can arise, for example, if stored mechanical energy within the adjustable roll stabilizer, particularly in the stabilizer sections, causes the actual motor position to overshoot the target motor position. In this case, it is advantageous to brake the motor before reaching the target motor position, i.e., to output a target motor torque in the opposite direction. Furthermore, braking may also be necessary due to external forces, such as road surface irregularities, acting from the wheel mounting points to the adjustable roll stabilizer, if the external force induces a torque in the direction required to reduce the control deviation.By means of quadrant monitoring 27 it is possible to check whether a motor target torque 23 determined by the position-speed controller appears plausible, especially with regard to previously described operating situations.

[0036] The square monitoring 27 of the position-speed cascade receives the motor target torque 23, the system angle α and the target angle α as input variables. Soll , as indicated by the arrows in Fig. Figure 3. In a manner yet to be described, taking into account the target angle α, Soll and the actual system angle α, a plausibility check of the motor target torque 23 was carried out.

[0037] This will be explained in detail using the following examples: Fig. Figure 4 explains in more detail, showing a graphical representation of a plausibility scheme according to a preferred embodiment of the invention. In the left area of ​​the Fig. Figure 4 shows the input variables for quadrant monitoring, i.e., the target angle α. Soll , the system angle α and the motor target torque 23 (see quadrant monitoring 27 in Fig. 3) For the plausibility check described by the invention, the control difference 24 between the target angle α is considered. Soll and system angle α.

[0038] For this purpose, a difference between these two input variables is first calculated, which is then used in the further plausibility check in the form of a control difference 24.

[0039] The plausibility check is essentially based on three branches. In relation to the presentation in Fig. 4 - The upper branch determines whether an existing control deviation (between the setpoint angle and the system angle) increases. A lower branch determines whether the motor setpoint torque 23 has an incorrect direction, i.e., one that increases the control deviation 24. Finally, a lower branch checks whether the motor torque 23 exceeds a threshold required to initiate the plausibility check.

[0040] As shown in the right part of the image Fig.As shown in Figure 4, the three branches mentioned are logically connected by an AND operation. Only when all three criteria checked in each branch are met is the AND condition satisfied and, after time debouncing 32, finally output as an error 33. The plausibility check therefore fails in the form of an error 33 (only) if the detected target motor torque 23 exceeds a minimum threshold, the control deviation increases, and at the same time the motor torque points in the wrong direction – i.e., in a direction that increases the control deviation.

[0041] For the upper branch (checking whether the control deviation is increasing), the control deviation 24 is first differentiated with respect to time and is thus available as derivative 24' of the control deviation. Alternatively, to achieve high robustness, the derivative of the actual position can be calculated and used (in the sense of: "is the actual position moving towards the target position?"). The next step involves checking the sign of derivative 24' of the control deviation (or derivative of the actual position) and, in parallel, of the control deviation 24. Using AND operations, the existence of two operating conditions is checked: In the first case, it is checked whether the derivative 24' of the control deviation is negative and the control deviation 24 is negative. Alternatively, it is checked whether the derivative 24' of the control deviation is positive and the control deviation 24 is positive.In each of the cases mentioned, if the AND condition is met, the result is that the rule deviation increases, which is output as a signal labeled 28 via an OR operation.

[0042] In the middle branch, a check is performed to determine whether the motor target torque 23 is pointing in the wrong direction. This check is based on the incoming control error 24 and the motor target torque 23. Specifically, it is checked whether the control error 24 is negative and the motor target torque 23 is positive, or alternatively, whether the control error 24 is positive and the motor target torque 23 is negative. If either of these cases is true, signal 29 is generated, indicating that the motor target torque 23 is increasing the control error 24.

[0043] As already mentioned, the lower branch checks whether the motor target torque 23 exceeds a minimum threshold.

[0044] Only if all three criteria checked in each branch are met is an error 33 ultimately output after time debouncing 32, resulting in a negative plausibility check. If at least one of the criteria is not met, the target motor torque is considered plausible. To further increase the robustness of the plausibility check, it is conceivable that, in addition to the three criteria, a threshold value of the control deviation could also be checked using an AND operator. Reference sign 1 adjustable roll stabilizer 2 actuator 3. Rotation axis 4 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 21 other various parameters 22 Vehicle speed 23 Motor target torque 24 Rule deviation 24' derivative rule difference 25 field-oriented regulation 26 Position-Speed ​​Cascade (LDK) - Level 1 27 Quadrant monitoring of the position-rotation cascade - Level 2 28. The rule deviation increases. 29 Motor target torque shows a direction increasing control deviation 30 Threshold for starting monitoring of the engine target torque 31 Engine torque is above filter threshold 32 Time Debouncing Buffer 33 errors z7a, z7b Height of left (or right) wheel M Wank Rolling moment (axis-related) M System System moment n engine speed α System angle α Soll Target angle (system)

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 system angle (α) with respect to an axis of rotation (3) in order to rotate two stabilizer sections (6a, 6b) connected thereto about the axis of rotation (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 away from the axis of rotation (3), wherein a position-speed controller is set from a target angle (α) to be set on the actuator (2). Soll ) and taking into account the actual system angle (α) as well as other parameters (21, 22) of the roll stabilizer (1) and / or the motor vehicle equipped with it, a target motor torque (23) is determined, on the basis of which a motor (4) of the actuator (2) is controlled, taking into account the target angle (α) Soll) and the actual system angle (α) a plausibility check of the motor target torque (23) is carried out. [2] Method according to claim 1, characterized by , that for the plausibility check a consideration of the control difference (24) between target angle (α Soll ) and system angle (α). [3] Method according to claim 1 or 2, characterized by that the plausibility check is based on at least two criteria, namely whether: the control deviation (24) between target angle (α Soll ) and system angle (α) increased, and the motor target torque (23) has a direction that increases the control deviation (24), whereby if both criteria are met the plausibility check is negative. [4] Method according to any of the preceding claims, characterized by, that the plausibility check is positive at least if the motor target torque (23) leads to a reduction of the control deviation (24) between target angle (α Soll ) and actual system angle (α). [5] Method according to any of the preceding claims, characterized by , that the plausibility check is only carried out when a threshold value of the motor target torque (23) and / or the control deviation (24) is exceeded. [6] Method according to any of the preceding claims, characterized by , that another parameter taken into account is the vehicle speed (22) of the motor vehicle equipped with the adjustable roll stabilizer (1). [7] Method according to any of the preceding claims, characterized by , that the determined motor target torque (23) for the actuator (2) is supplied to a field-oriented control (25) which controls a motor (4) assigned to the actuator (2). [8] Method according to any of the preceding claims, characterized by , that the target angle (α) to be set at the actuator (2) Soll ) is determined taking into account a reference variable and a disturbance-compensating variable. [9] Method according to claim 8, characterized by , that the reference variable is a rotation angle for a vehicle-side torque request and the disturbance-compensating variable is a zero-torque angle, wherein the rotation angle for the torque request and the zero-torque angle are related to the target angle (α) to be set on the actuator (2). Soll ) are added. [10] System for roll stabilization configured to perform a method according to any of the preceding claims.

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