Method for controlling an actuator motor on a split anti-roll bar of a vehicle

Abstract

A method for controlling an electric actuator motor provided on a split anti-roll bar in the chassis of a two-track vehicle, with which the two halves of the split anti-roll bar can be torsionally adjusted relative to each other, and wherein an electronic control unit exclusively assigned to the actuator motor is provided, which, in the event of a higher-level fault that prevents the desired positioning of the anti-roll bar halves relative to each other adapted to the respective driving state of the vehicle, becomes effective in such a way that sufficient driving stability is achieved, characterized in that, in the event of a fault, at least the actuator motor of the anti-roll bar provided on the front axle of the vehicle is controlled by the assigned electronic control unit in such a way that this anti-roll bar behaves like a non-split passive anti-roll bar, in that the so-calledThe base angle between the two stabilizer halves is actively maintained, which is established without the influence of driving dynamic forces on a surface that is essentially horizontal and level, at least when viewed in the transverse direction of the vehicle, and which is determined by the associated electronic control unit in at least one corresponding operating state after the vehicle has been put into operation.

Description

[0001] The invention relates to a method for controlling an electric actuator provided on a split anti-roll bar in the chassis of a two-track vehicle, by which the two halves of the split anti-roll bar can be torsionally adjusted relative to each other, and wherein an electronic control unit exclusively assigned to the actuator is provided, which, in the event of a higher-level fault that prevents the desired positioning of the anti-roll bar halves relative to each other adapted to the respective driving condition of the vehicle, becomes effective in such a way as to achieve sufficient driving stability. For the prior art, reference is made to DE 10 2005 021 673 A1 and DE 102 21 716 A1.

[0002] Systems for regulating the roll behavior of two-track motor vehicles, whose primary objective is to reduce the roll angle and thereby increase ride comfort, driving safety, and agility, are known in various embodiments. These can be broadly divided into passive, switchable, semi-active, and active roll stabilization systems, with the present invention relating to the latter design in the form of an active lateral stabilizer. While the counterforces applied by a passive lateral stabilizer result directly from the relative movements of the body to the wheel, active systems enable the targeted application of counter-torques. These are controlled, 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,The design incorporates an active split anti-roll bar, whose two halves can be torsionally adjusted relative to each other. This improves the vehicle's self-steering behavior by distributing the stabilizer torques between the front and rear axles according to driving conditions. Furthermore, it reduces copy effects on uneven road surfaces due to the extensive decoupling of the stabilizer halves. The desired counter-torque can be applied hydraulically or electrically by twisting the left and right stabilizer halves relative to each other using a suitable actuator or motor. Such an electromechanical or electromotor-driven roll stabilization system is described, for example, in DE 10 2008 053 ​​481 A1.

[0003] For active and therefore controllable systems, the possibility of system malfunctions must be considered and a suitable response provided. German patent DE 10 2005 021 673 A1 describes an emergency operating solution for electromechanical roll stabilization actuators in the form of a locking device that engages positively only when the vehicle is in a neutral angular position (i.e., with the vehicle in an indicated horizontal orientation) during emergency operation. This prevents an undesired tilting of the vehicle body. A key advantage is the independence of the mechanical locking device from an electronic control unit, which itself can be the cause of a malfunction.In the aforementioned German patent DE 102 21 716 A1, an electronic control system for a corresponding electromechanical roll stabilization device for a passenger car is described. Each electric actuator is assigned power electronics with a low-level controller and low-level monitoring logic, which are connected via a data bus to a high-level control unit. This higher-level control unit performs superior control and appropriately distributes the stabilizing torque required for roll stabilization between the front and rear axles of the vehicle. It also contains high-level monitoring logic. In a so-called fail-safe mode, i.e., when a more or less serious fault is detected and the overall system needs to be brought into a safe operating state, each electric actuator is disconnected from the power output stage of its associated power electronics and short-circuited via a defined load resistor.

[0004] In electromechanical roll stabilization systems, a fail-safe mode presents a greater challenge than in hydraulically torsionally adjustable stabilizer halves, since in the event of a fault, a safe torque distribution cannot be achieved mechanically, at least not immediately, and even then only in a relatively complex manner (see the aforementioned DE 10 2005 021 673 A1). While automatic braking interventions can be implemented to increase driving safety, this leaves vehicle occupants with a subjective feeling of insecurity due to significantly reduced roll support. Furthermore, such braking interventions cannot be carried out in the event of a higher-level fault, which could, for example, originate in a control unit governing the vehicle's vertical and lateral dynamics or in its communication with subsystems, i.e., in the vehicle's data bus system.In contrast, the solution described in the already mentioned DE 102 21 716 A1, which involves short-circuiting the electric actuators in the split stabilizers, is more favorable. However, when using appropriately dimensioned electric motors, this only provides relatively little roll stabilization, which can make the subjective driving experience for the vehicle's occupants unusual or unpleasant, and may also prevent the desired level of driving safety from being ensured.

[0005] JP 2010-052515 A discloses a control system for controlling an electromagnetic actuator with an electromagnetic motor. DE 198 46 275 A1 discloses a system and method for roll stabilization of vehicles.

[0006] The object of the present invention is therefore to provide a remedy for this problem described above.

[0007] The solution to this problem is characterized for a method for controlling an electric actuator provided on a split anti-roll bar in the chassis of a two-track vehicle according to the preamble of claim 1 in that at least the actuator of the anti-roll bar provided on the front axle of the vehicle is controlled by the associated electronic control unit in the event of a malfunction in such a way that this anti-roll bar behaves like a non-split passive anti-roll bar by actively maintaining the so-called base angle between the two stabilizer halves which is established without the influence of vehicle dynamic forces on a surface that is essentially horizontal and level, at least when viewed in the transverse direction of the vehicle, wherein this base angle is determined by the associated electronic control unit in at least one corresponding operating state after the vehicle has been put into operation.Preferably, the determined base angle is set as a baseline in the electronic control unit. From this baseline, continuous changes in the rotation angle made by the actuator are summed, taking the direction of rotation into account. If necessary, the required rotation angle of the actuator to adjust the base angle is then determined. In an advantageous further development, the actuator located on the rear axle of the vehicle can be disabled in the event of a malfunction, i.e., it simply cannot be controlled.

[0008] The plan is therefore to assign a separate electronic control unit to the actuator of each split anti-roll bar, which can control the actuator to set a desired angle of twist between the two anti-roll bar halves. Preferably, under normal circumstances, this electronic control unit receives the desired angle of twist, or similar information, from a higher-level control system responsible for adjusting the vehicle's driving dynamics with regard to vertical, lateral, and / or longitudinal dynamics. If, due to any higher-level malfunction, such as...If such a command is issued, which may be caused by the failure of a driving condition sensor, this stabilizer-specific control unit enters a safety mode in which a fault response is implemented. As a result, the split anti-roll bar behaves like a non-split anti-roll bar, with the electric actuator essentially coupling the two anti-roll bar halves together in a sensible position. For this to happen, the actuator must continuously position the two anti-roll bar halves in such a way as to a so-called "zero position," in which the two anti-roll bar halves are located relative to each other without the influence of driving dynamic forces on a substantially horizontal road surface or on a horizontal, level surface. Positioning in this zero position is sensibly carried out via a control process, so that no exact positioning occurs, but rather a small control deviation is always maintained for a specific purpose.The simple and reliable proportional (P) controller will be used. The angle of rotation between the stabilizer halves in the aforementioned zero position, or the corresponding positional rotation angle of the actuator motor, is defined and hereinafter referred to as the "base angle." Ideally, the vehicle should be evenly loaded to determine this base angle, and preferably the vehicle body should be in at least approximately its design position. However, the primary requirement for determining the base angle is that no dynamic forces act on the vehicle, which is standing on a substantially horizontal road surface or level ground, so that ideally, in this zero position, the stabilizer transmits no moment between the two sides of the vehicle.

[0009] If the system, and in particular the actuator motor, has the capability to measure the angle of rotation between the stabilizer halves, it is particularly easy, if necessary (i.e., in the event of a system malfunction), to control the actuator motor so that the aforementioned base angle, and thus the aforementioned zero position, is set. As a result, the split stabilizer, "actively operated" according to the invention, behaves like a passive, non-split stabilizer. However, the electric actuators or actuator motors typically used for a vehicle's roll stabilization system between split stabilizers do not contain such angle-measuring sensors that can determine the effective angle of rotation between the two stabilizer halves at any time and thus provide it as a control variable. Rather, only a temporally "relative" angle of rotation relative to a starting point of the (among other things)The system (formed by the actuator motor) is monitored, whereby, within the framework of or as a further development of the present invention, the aforementioned starting point is set at the first or recurring occurrence of the said zero position. Accordingly, the electronic control unit assigned to the (respective) split transverse stabilizer learns this zero position by determining it itself and, based on this learning process, continuously monitors the rotational movements carried out by the actuator motor between the two stabilizer halves during regular, undisturbed operation in order to know the current "relative position" of the two stabilizer halves to each other at any given time.This allows the electronic control unit to bring the two stabilizer halves into the aforementioned zero position if necessary, namely in the event of a higher-level fault, since only the changes in the rotation angle that have been continuously accumulated since the learning process, taking into account the direction of rotation, need to be reversed above the determined sum value in order to reach the base angle or the zero position.

[0010] Since the supply of electrical energy to electronic control units is usually discontinued as far as possible when a vehicle is switched off or stopped, the method according to the invention further provides that this zero position is re-determined by the electronic control unit after the vehicle has been started up, in a corresponding operating state of the vehicle in which no dynamic forces act on the vehicle or the vehicle body and the vehicle is located on a roadway or on a level surface that is essentially horizontal, at least in the transverse direction of the vehicle. The electronic control unit can easily determine, for example, that no dynamic forces are acting on the vehicle by observing that the vehicle is stationary, whereas on typical roads where a vehicle is parked or, for example, stopped at a "red" traffic light, which is, for example,Based on navigation data, it can be determined that the vehicle is brought to a standstill, and that the ground is essentially horizontal when viewed from the vehicle's side. If the vehicle is equipped with known level sensors capable of measuring the vehicle's height relative to at least two wheels, this can also be used to infer a horizontal surface from the vehicle's side with sufficient accuracy, neglecting the effects of uneven loading. It should be explicitly noted that the determination of the relative angle of the "zero position" does not necessarily have to be performed only once immediately after the vehicle is put into operation, but can also be determined continuously under suitable operating conditions after a certain period of operation or, by appropriately considering the relevant driving condition information, even while driving.

[0011] To ensure maximum distribution of the effective stabilizer torque to the front axle of the vehicle, which, as is known, results in maximum possible yaw stability, the inventive so-called zero-position control, with which the actuator motor operates as described in the event of a malfunction, can be implemented exclusively on the front axle of the vehicle, while the actuator motor on the rear axle is deactivated, i.e., simply not controlled. As a result, the two stabilizer halves of the rear axle can rotate almost independently of each other. Even in this case of a malfunction, roll stabilization that ensures an acceptable level of comfort can still be achieved.

Claims

[1] Method for controlling an electric actuator provided on a split anti-roll bar in the chassis of a two-track vehicle, with which the two halves of the split anti-roll bar can be torsionally adjusted relative to each other and wherein an electronic control unit exclusively assigned to the actuator is provided, which in the event of a higher-level fault, due to which a desired positioning of the anti-roll bar halves relative to each other adapted to the respective driving state of the vehicle is not possible, becomes effective in such a way that sufficient driving stability is achieved, characterized by, that at least the actuator of the anti-roll bar provided on the front axle of the vehicle is controlled by the associated electronic control unit in the event of a malfunction in such a way that this anti-roll bar behaves like a non-divided passive anti-roll bar by actively maintaining the so-called base angle between the two stabilizer halves which is established without the influence of driving dynamic forces on a surface that is essentially horizontal and level, at least when viewed in the transverse direction of the vehicle, and that this base angle is determined by the associated electronic control unit in at least one corresponding operating state after the vehicle has been put into operation. [2] Method according to claim 1, wherein the base angle is set as the basis in the electronic control unit, from which continuously changes in the angle of rotation made by the actuator are summed up taking into account the direction of rotation, and from this the necessary angle of rotation of the actuator for setting the base angle is determined. [3] Method according to claim 1, characterized by , that the actuator motor provided on the rear axle of the vehicle will not be activated in the event of a malfunction.