WO2018028746A1

WO2018028746A1 - Method for operating an electric servomotor, roll stabilizer device, and vehicle

Info

Publication number: WO2018028746A1
Application number: PCT/DE2017/100660
Authority: WO
Inventors: Christoph Sauer; Dominik Reif
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2016-08-11
Filing date: 2017-08-04
Publication date: 2018-02-15
Also published as: DE102016215004B4; DE102016215004A1

Abstract

The invention relates to a method for operating an electric servomotor (12), which on the basis of a target variable (MS) generates a torque (M) between two parts (10a, b) of a roll stabilizer (8), in which method, in a normal mode (BN), a variable controller (16) generates the target variable (MS) for the servomotor (12) on the basis of a default variable (MV) and an actual variable (MI) between the parts (10 a, b), wherein it is monitored whether there is an error (F) in the normal mode (BN), and in the event of an error (F), an emergency variable (MN) is detected in a fault mode (BF), and is supplied to the servomotor (12) instead of the target variable (MS). A roll stabilizer device (6) having a roll stabilizer (8), a servomotor (12), and a variable controller (16), comprises a control and evaluation unit (26) for the method described above. In a two-track vehicle (2) having a roll stabilizer device (6), the chassis (4) contains the roll stabilizer (8) thereof.

Description

Method for operating an electric servomotor, roll stabilizer device and vehicle

The invention relates to an electric servomotor which generates a torque between two parts of a split roll stabilizer for a chassis of a two-lane vehicle.

Systems for regulating the roll behavior of two-lane motor vehicles are known in various embodiments. Their primary objective is to reduce the roll angle and, as a result, to increase ride comfort, driving safety and agility. The systems are roughly subdivided into passive, switchable, semi-active and active anti-roll bar systems, the present invention being related to the latter design in the form of an active anti-roll bar. While the opposing forces applied by a passive anti-roll bar result directly from the relative movements of the structure to the wheel, active systems allow the targeted application of counter-moments. Their control takes place, for example, as a function of the lateral acceleration and / or the roll angle of the motor vehicle. In addition to a reduced roll motion of the vehicle body can be achieved with an active split anti-roll bar, the two halves against each other, an improved self-steering behavior of the vehicle by a driving state-dependent distribution of stabilizer moments between the front and rear of the vehicle, and there are less copy effects in unilateral road bumps by a substantial decoupling of the stabilizer halves. In this case, a desired counter-torque mentioned above can be provided hydraulically or electromotively by the left and right stabilizer halves being rotated against each other by means of a suitable actuator or motor. The invention relates to systems with electric servomotor. An electromechanical or electromotive roll stabilization system is described for example in DE 10 2008 053 481 A1. In the case of active and thus controllable systems, the possibilities of disturbances in the system must always be taken into account and a suitable reaction provided thereon. In electro-mechanical roll stabilization systems, therefore, a failsafe mode is desirable. It is conceivable, for example, a higher-level disturbance, which could be present for example in a control unit controlling the vertical dynamics and the lateral dynamics of the motor vehicle or in their communication with subsystems, ie in a data bus system of the vehicle. From DE 10 2013 203 442 A1 a method is known in which an electric servomotor is controlled on a divided anti-roll bar in the chassis of a two-lane vehicle so that the anti-roll bar behaves like an undivided passive anti-roll bar by a base angle between the two stabilizer halves is kept active. In other words, in the roll stabilizer, the engine performs a zero position control in the event of a fault, whereby a passive stabilizer is imitated.

Object of the present invention is to respond to disturbances in and around a roll stabilizer with two parts and electric servomotor.

The object is achieved by a method according to claim 1. Preferred or advantageous embodiments of the invention and other categories of invention will become apparent from the other claims, the following description and the accompanying drawings.

The method is a method for operating an electric servomotor. The electric servomotor generates a torque between two parts of a shared roll stabilizer on the basis of a target quantity supplied to it, in particular a desired torque. For the sake of clarity and readability, in the context of this description, without limiting the general validity or the patent claims, the "size" is generally described as "moment" in the embodiment. However, this is only representative of other "sizes" such as strength, Position or torsion, etc. If the "setpoint torque", but the setpoint force, setpoint motor position, setpoint torsion, etc., are not supplied as the setpoint size, a force / position / "torque" occurs here instead of the "moment". Torsion, etc. The invention applies mutatis mutandis to these other cases. The roll stabilizer is one for a chassis of a two-lane vehicle.

In an error-free, i. regular or normal operation, the following happens:

A size controller, in particular a torque controller, generates the desired value for the servomotor based on a default torque (representative of the default value) and a measured actual torque (deputy for actual size). In addition to the above, it is once again mentioned that the "torque controller" is merely representative of "force / position ATorsion controller", etc. The default torque refers to a torque or torque between the two parts of the roll stabilizer and is fed to the torque controller. In particular, the default torque is provided to the torque controller by means of a communication. The actual moment also refers to the moment between the two parts. The movements and moments in the roll stabilizer relate to a torsion axis of the roll stabilizer, about which the two parts are twistable against each other. That the default torque is provided by means of "communication" means that this is supplied in particular to the torque controller via a communication interface, for example, starting from a higher-level control unit via a corresponding signal line.

According to the method, the target torque is supplied to the servomotor.

"Measured" means that the actual moment, which is currently present between the two parts of the roll stabilizer, is determined directly or indirectly in any manner Alternatively, as explained above, for example, the measurement of a force and the calculation of the force or Moment with the help of the stiffness of a torsion bar and the measurement of a torsion angle of the torsion bar. The same applies, for example, for a speed of the servomotor, which is currently available.

According to the method, it is monitored whether the normal operation has an error. In the case of the occurrence or recognition of any corresponding error, an error operation is started according to the method. In this an emergency torque (deputy for emergency size) is determined and supplied to the servomotor the emergency torque instead of the target torque. The invention is based on the idea that in the case of recognizing any error is no longer ensured that the target torque is determined correctly and thus the servomotor is operated as desired. The "target torque" is an engine torque, ie the output of the size regulator. It is therefore not here, for example. to the specification of the torque controller (default torque). For safety's sake, therefore, a substitute value for the target torque, namely an emergency torque, is at least partially determined independently of the above-described procedure according to normal operation, and this supplied to the servomotor as a default. Thus, critical driving situations can be avoided in a vehicle with a corresponding roll stabilizer.

In a preferred embodiment, the case is considered that the error relates to the actual moment. In this case, in fault mode, a substitute torque (deputy for substitute variable) is determined for the actual torque and the torque controller is supplied with the substitute torque instead of the actual torque. Apart from this deviation, the procedure is otherwise the same as in normal operation in error mode. That is, it is equally determined a "target moment" according to the above procedure, which then represents the emergency moment. In this case, therefore, the emergency torque is determined from the replacement torque with the aid of the default torque and the torque controller. Only in the torque controller, the replacement torque is used instead of the actual torque. The determined "desired torque" thus represents the emergency torque and is supplied to the servomotor. The error relates in particular to a failure of or a faulty measurement on a sensor for the actual torque, an error on a signal line via which the actual torque is transmitted to the torque controller, or an input on the torque controller, via which the actual torque of this is accepted, and so on.

According to this embodiment, therefore, the error-free components of the normal operation are further used in accordance with this to perform almost the regular procedure, only a spare torque is used instead of the actual torque. Accordingly, high-quality emergency moments can be generated.

In a preferred variant of this embodiment, the replacement torque is determined on the basis of a physical model of the roll stabilizer. As a result, replacement moments can be generated or determined which usually approximate the measured actual moments, so that high-quality emergency moments are generated.

In a preferred embodiment, the case is considered that the error relates to the torque controller and / or the actual torque. In error mode, a torque control (deputy for size control) then determines the setpoint value instead of the torque controller. This does this alone on the basis of the default moment, without considering the actual moment further. The target size is thus determined only in a controlled manner alone from the default moment and no longer in a regulated manner additionally based on the actual moment. The torque controller is no longer used, but a corresponding torque control is used as a replacement. Otherwise - as described above - the "target torque" in the form of the emergency torque as determined in normal operation and fed to the servomotor. Although the emergency moment is no longer based on a regulated, but at least on a controlled size and is therefore still variable or situation-dependent adapted. Thus, a high quality emergency response is still provided. In a preferred variant of this embodiment, the desired value is determined by the torque control with the help of an inverse physical model of the roll stabilizer based on the default torque. The torque control thus forms the roll stabilizer in an inverse manner and thus generates high-quality setpoint variables on the basis of the supplied default moments. Even so, a high quality emergency response is ensured.

A preferred embodiment relates to the case that the error does not affect an actual speed. This is especially the case when the setpoint for the torque controller (default torque) is faulty or breaks off a communication that is used to transmit the default torque to the torque controller or missing the setpoint for the torque control. In error mode, the emergency torque is determined based on a replacement instruction from the actual speed. The replacement rule is chosen so that the servomotor causes a damping operation of the roll stabilizer. Each (especially caused from the outside) rotation or torsion of the roll stabilizer is thus (in particular by the servo motor) opposed to an opposing moment, which is in particular smaller than the torque causing the torsion. This embodiment is suitable for almost any error cases, since only the actual speed is needed, especially for those who the default torque or the communication over which the default torque is provided concerns. This measure thus intervenes for errors in the communication to the rest of the vehicle and errors in the torque controller. According to this variant, an emergency torque is still provided even in the case of a serious system fault, in order to be able to specify an emergency torque for the servomotor, at least based on the replacement rule. At least the actual speed of the servomotor is thus included in the replacement rule, so that the replacement instruction is parameterized accordingly. In this way, an emergency torque dependent on the actual speed can be generated.

In a preferred variant of this embodiment, an emergency torque is determined according to the replacement rule, which corresponds to an actual direction of rotation of Actuator is directed opposite and dependent on its actual speed. In particular, the direction of rotation is determined in such a way that it is checked whether the actual rotational speed has a positive (then a corresponding first rotational direction) or a negative value (then different rotational direction). Thus, depending on the speed, effective and high quality damping in the system can be achieved.

In a preferred variant of this embodiment, the emergency torque is determined directly proportional to the actual speed. Thus, even with only intact actual speed, a high quality emergency torque can be provided as a damping torque available.

The object of the invention is also achieved by a roll stabilizer device. This includes a roll stabilizer for a chassis of a two-lane vehicle, the roll stabilizer is divided into two parts. The roll stabilizer device includes a servo motor configured to generate a torque between the two parts according to a target amount (target torque). The device includes a size controller (torque controller) arranged to set a target size for the servomotor based on a preset amount (default torque) between the two parts and a measured actual size (actual torque) between the two parts to create. The roll stabilizer device contains a control and evaluation unit. This is set up to carry out the method according to the invention. The roll stabilizer device and at least some of its embodiments as well as the respective advantages have already been explained analogously in connection with the method according to the invention. In particular, the control and evaluation unit includes a means for generating the replacement torque and / or a physical model of the roll stabilizer and / or a torque control and / or an inverse physical model of the roll stabilizer and / or a means for implementing the replacement rule and / or a computing unit for Calculation of the directly proportional emergency torque from the actual speed. The roll stabilizer device is thus equipped accordingly to be able to carry out all variants of the above-mentioned method. The object of the invention is also achieved by a vehicle which is a two-lane vehicle and includes a chassis. The vehicle includes a roll stabilizer device according to the invention. The chassis of the vehicle contains the roll stabilizer of the roll stabilizer device. The vehicle and at least a part of its embodiments and the respective advantages have been explained analogously already in connection with the roll stabilizer device according to the invention and the method according to the invention.

The invention is based on the following findings or considerations, in which context embodiments of the invention are also mentioned as the invention, which correspond to combinations of the abovementioned embodiments and / or optionally also include previously not mentioned embodiments.

The invention describes a fail-safe concept for an electromechanical roll stabilizer. The invention describes an alternative solution to the solution known from DE 10 2013 203 442 A1. According to the invention, in a certain error case, a torque replacement value is regulated based on a model of the roll stabilizer. In the case of a lack of communication with the vehicle, a constant speed-dependent attenuation should be set. In the event of a failure of the torque sensor, critical driving situations can occur. To avoid this, a failure value of the torque sensor is set to a substitute value. This substitute value is generated in a physical model of the actuator. On the other hand, if there is a failure of the communication to the higher-level control unit, the information of the moment to be set (default moment) is missing. A reasonable assumption can not be made here on the level of the actuator. In order to increase the stability of the vehicle, an attenuation at the front axle and / or the rear axle is set in this case of error. In this case, the servo motor requests a rotational speed proportional to its rotational speed that is proportional to its rotational speed. The servomotor thus acts as a torsional vibration damper.

Further features, effects and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. 1 shows a vehicle with a roll stabilizer device in normal operation, FIG.

FIG. 2 shows the roll stabilizer device in an error mode;

FIG. 3 shows the roll stabilizer device in an alternative fault mode;

FIG. 4 shows the roll stabilizer device in a further alternative error mode. Figure 1 shows strongly symbolizes a section of a two-lane vehicle 2 with a chassis 4. The vehicle 2 includes a roll stabilizer device 6 with a roll stabilizer 8, wherein the chassis 4 includes the roll stabilizer 8. The roll stabilizer 8 is divided into two parts 10a, b and twisted about a torsion axis 14 against each other. The roll stabilizer device 6 contains a servo motor 12 which generates a torque M around the torsion axis 14 between the two parts 10a, b during operation or when required. This is done in a normal operation BN of the roll stabilizer device 6 in accordance with specification of a desired torque MS, which is supplied to the servomotor 12. The roll stabilizer device 6 contains a torque controller 16, which generates the desired torque MS for the servomotor 12 on the basis of a default torque MV and an actual torque MI. The default torque MV is provided to the torque controller 16 by means of a communication 18, which is only indicated symbolically here. Specifically, in the example, the default torque MV is provided by a belonging to the vehicle 2, the roll stabilizer device 6 higher-level control 20 or communicates with the torque controller 16. The default torque MV is a default value for the moment M acting between the two parts 10a, b should. The actual moment MI is the moment M currently measured between the two parts 10a, b. In the example, the actual moment MI is determined by a moment sensor 22. The previously described procedure takes place in a normal mode BN, which is summarized again as follows:

The servo motor 12 generates the torque M between the two parts 10a, b of the roll stabilizer 8 in the chassis 4 of the vehicle 2 based on the specification of the desired torque MS. The torque controller 16 determines the desired torque MS on the basis of the provided by the communication 18 default torque MV and the measured actual torque MI. The desired torque MS is supplied to the servomotor 12.

The roll stabilizer device 6 also contains a control and evaluation unit 26 which is only indicated in FIG. 1 and which is set up to carry out the method described below.

It is monitored whether an error F is detected during normal operation. If such is detected, an error operation BF is started and an emergency torque MN is determined and the emergency motor MN is supplied to the servomotor 12 instead of the setpoint torque MS. In this case, the error F can occur in any component of the components and processes involved in the normal operation and is shown only symbolically in FIG. 1 by exemplary arrows.

FIG. 2 shows a first fault operation BF of the roll stabilizer device 6, in which the fault F relates to the actual moment MI. For example, the torque sensor 22 fails or provides erroneous values and / or the transmission from the torque sensor 22 to the torque controller 16 is faulty. Both components are only indicated by dashed lines in order to indicate the potential defectiveness at least at one point of the dashed components. This solution can therefore be used for all errors that occur at any point in the dashed components. In error mode BF, a replacement torque ME for or instead of the actual torque MI is determined, and the torque controller 16 is supplied with the substitute torque ME instead of the actual torque MI. The remaining components are also in the Error operation, but operated in accordance with the normal operation BN, so that the emergency torque MN is determined on the otherwise same way as the target torque MS and output. In the example, the replacement moment ME is determined on the basis of a physical model 28 of the roll stabilizer 8, but it could also be determined in any other way. The model 28 and the generation of the replacement torque ME is in this case part or done by the control and evaluation unit 26, as indicated by dashed lines in the figure.

FIG. 3 shows the roll stabilizer device 6 with an alternative fault F, which relates to the actual moment MI and / or the torque controller 16, which is why these components are again shown in dashed lines. The perturbation has the same meaning as above, i. stands for any errors in at least one place of the sthchelung. In error mode BF, the emergency torque MN is no longer determined on the basis of the torque controller 16, but on the basis of a torque control 30 here. This is done on the basis of the default torque MV as in normal operation BN. Since it is a control instead of a control, unlike the normal operation BN feedback in the form of the supply of the actual moment MI is no longer necessary. Otherwise, the emergency torque MN is again determined the same as in normal operation BN. The torque control 30 contains an inverse physical model 32 of the roll stabilizer 8, based on or with the aid of which the emergency torque MN is determined from the default torque MV. In this case, the torque control 30 and the inverse model 32 are components of the control and evaluation unit 26 (indicated by dashed lines).

Figure 4 shows another case in which the error F affects almost all components of the roll stabilizer device 6, which are involved in normal operation BN Exempt or error-free is only an actual speed DI or is this error-free. The actual speed DI is the current speed of the servomotor 12, which is measured at this. The potentially faulty components are again shown in dashed lines. The Sthchelung has the same meaning as meaning above, ie stands for any errors in at least one place of the dashes. In error mode BF, the emergency torque MN is determined from the actual speed DI based on a replacement instruction VE. The replacement instruction VE is chosen so that the servomotor 12 causes a damping operation of the roll stabilizer 8. That is, depending on the actual actual speed DI measured on the roll stabilizer 8, the servo motor 12 generates a damping counteracting moment M.

According to the replacement instruction VE an emergency torque MN is thus determined, which is opposite to an actual direction of rotation of the servomotor 12 and is dependent on its actual speed DI. The direction of rotation is determined based on the sign of the value of the actual speed DI. Positive values mean a certain direction of rotation, negative values mean the opposite direction of rotation. In particular, the emergency torque MN is directly proportional to the actual speed DI with the proportionality factor k> 0 in accordance with the formula MN = -k ^* DI as a replacement instruction VE.

LIST OF REFERENCE NUMBERS

2 vehicle

4 suspension

6 roll stabilizer device

8 roll stabilizer

10a, b part

12 servomotor

14 torsion axis

16 torque control (size control)

18 communication

20 control

22 moment sensor (size sensor)

26 control and evaluation unit

28 model

30 torque control (size control)

32 inverse model

M torque

MS target torque (target size)

MV default torque (default size)

MI actual moment (actual size)

ME replacement moment (replacement size)

MN emergency moment (emergency size)

DI actual speed

BN normal operation

BF error operation

F mistake

VE replacement instruction

Claims

claims

1 . Method for operating an electric servomotor (12), which uses a setpoint variable (MS) supplied to it to generate a torque (M) between two parts (10a, b) of a divided roll stabilizer (8) for a chassis (4) of a two-lane vehicle ( 2), in which in normal operation (BN):

- A size controller (16) the target size (MS) for the servo motor (12) based on a the size controller (16) supplied default variable (MV) between the two parts (10a, b) and a measured actual size (MI ) generated between the two parts (10a, b),

- The desired size (MS) is supplied to the servomotor (12),

characterized in that

- It is monitored whether the normal operation (BN) has an error (F), and

- in case of an error (F) in an error mode (BF):

- an emergency size (MN) is determined, and

- The servo motor (12), the emergency size (MN) instead of the target size (MS) is supplied.

2. The method according to claim 1,

characterized in that

in the case that the error (F) relates to the actual quantity (MI):

- In error mode (BF), a replacement size (ME) for the actual size (MI) is determined, and the size controller (16), the replacement size (ME) instead of the actual size (MI) is supplied.

3. The method according to claim 2,

characterized in that

the substitute variable (ME) is determined on the basis of a physical model (28) of the roll stabilizer (8).

4. The method according to any one of the preceding claims, characterized in that

in the case that the error (F) relates to the size controller (16) and / or the actual quantity (MI):

- In error mode (BF) a size control (30) instead of the size controller (16) determines the target size (MS) based on the default size (MV).

5. The method according to claim 4,

characterized in that

the desired value (MS) is determined by the size controller (30) with the help of an inverse physical model (32) of the roll stabilizer (8) on the basis of the default variable (MV).

6. The method according to any one of the preceding claims,

characterized in that

in case the error (F) does not affect an actual speed (DI):

in error mode (BF), the emergency quantity (MN) is determined from the actual speed (DI) on the basis of a replacement instruction (VE), wherein the replacement instruction (VE) is selected so that the servomotor (12) performs a damping operation of the roll stabilizer (FIG. 8) causes.

7. The method according to claim 6,

characterized in that

According to the replacement instruction (VE) an emergency quantity (MN) is determined, which is opposite to an actual direction of rotation of the servomotor (12) and is dependent on its actual speed (DI).

8. The method according to claim 7,

characterized in that

the emergency size (MN) is determined directly proportional to the actual speed (DI).

9. roll stabilizer device (6),

- with a roll stabilizer (8) for a chassis (4) of a two-lane vehicle (2), which is divided into two parts (10 a, b), with a servomotor (12) which is set up to generate a torque (M) between the two parts (10a, b) in accordance with a desired quantity (MS) supplied to it,

- With a size controller (16) which is adapted to the target size (MS) for the servo motor (12) based on a size regulator (16) supplied default variable (MV) between the two parts (10a, b) and a measured actual variable (MI) between the two parts (10a, b) to produce

characterized in that

the roll stabilizer means (6) includes a control and evaluation unit (26) adapted to carry out a method according to any one of claims 1 to 8.

10. vehicle (2), which is a two-lane vehicle, with a chassis (4),

characterized in that

the vehicle (2) includes a roll stabilizer device (6) according to claim 9, wherein the chassis (4) of the vehicle (2) includes the roll stabilizer (8) of the roll stabilizer device (6).