Active roll stabilization with improved control via a setpoint limit.

Abstract

Method for actively stabilizing the roll of a vehicle by means of a roll stabilizer (30), wherein the roll stabilizer (30) comprises a stabilizer bar (32), a stabilizer housing (34) and a stabilizer motor (36) arranged in the stabilizer housing (34), such that the stabilizer bar (32) is connected at a first end to a wheel of the vehicle and is rotatably mounted at a second end by means of the stabilizer motor (36), the method comprising: - Obtaining an initial setpoint value of a rod torque of the stabilizer bar (32); - Obtaining a second setpoint of a motor rotation angle of the stabilizer motor (36); - Limiting the second setpoint based on an absolute value and / or a gradient of the first setpoint; - Inputting the second setpoint into a control loop (20) as a reference variable.

Description

TECHNICAL AREA

[0001] The present invention relates to the field of roll stabilization for vehicles. In particular, the present invention relates to a method, a control device, an active roll stabilizer, a vehicle, a computer program product, a computer-readable medium, and a data signal. TECHNICAL BACKGROUND

[0002] Vehicle stability plays a crucial role in safety and driving comfort. Especially in larger vehicle classes, such as SUVs and buses, the vehicle tends to roll when cornering due to its higher center of gravity. Uneven road surfaces can also lead to instability.

[0003] Anti-roll bars are known from the prior art that have a tube connection between two wheels of the front or rear axle. A motor is installed in this tube connection, which is controlled to counteract the vehicle's roll by means of a relative rotation between two stabilizer tubes assigned to the two wheels. The motor control is often based on a control method.

[0004] The control methods used in known roll stabilizers have the disadvantage that it is not guaranteed that the stabilizer motor, and in particular the synchronous motor installed within it, always operates within a defined range with regard to motor torque and travel speed. For example, it is impossible to prevent the stabilizer motor from operating simultaneously with high motor torque and high travel speed.

[0005] From DE 10 2013 110 953 A1, a control method with setpoints for rod torque and motor rotation angle is known. However, this contains no indication of a limit on a setpoint for the motor rotation angle.

[0006] DE 10 2008 024 092 A1, DE 60 2005 002 279 T2, DE 10 2018 107 646 A1 reveal forms of restricted control of a stabilizer motor. However, they do not indicate the limitation of a second setpoint or its input into a control loop as a reference variable.

[0007] The invention is based on the objective of improving the control method for a stabilizer and the latter in such a way that the stabilizer motor is always operated within the defined working range with regard to motor torque and travel speed.

[0008] The problem is solved by a method, a control device, a roll stabilizer, a vehicle, a computer program product, a computer-readable medium and a data signal according to the independent claims.

[0009] The inventive method for roll stabilization uses a roll stabilizer comprising a stabilizer bar, a stabilizer housing, and a stabilizer motor arranged in the stabilizer housing. The stabilizer bar is connected at a first end to a wheel of the vehicle and rotatably mounted at a second end by means of the stabilizer motor. The stabilizer bar is preferably designed as a stabilizer tube.

[0010] In one embodiment, the roll stabilizer has two stabilizer bars, which together are assigned to the front or rear axle of the vehicle and each is connected to one of the two wheels of the axle. The stabilizer housing is preferably connected to each of the two stabilizer bars on both sides. In this case, the stabilizer motor can act as a common rotary drive for both stabilizer bars. A gearbox for converting the motor speed into the bar speed can be arranged between the stabilizer motor and the stabilizer bar.

[0011] One or more additional components may be integrated into the roll stabilizer. These additional components may include a decoupling element, a connecting rod, and / or a stabilizer bearing.

[0012] During operation of the roll stabilizer, the rotor of the stabilizer motor, connected to the engine-side end of the stabilizer bar (for example, via an interposed gearbox), rotates. Due to this rotary connection, the motor rotation angle of the stabilizer motor and the engine-side rotation angle of the stabilizer bar are identical, except for the gear ratio of the interposed gearbox. The engine torque is thus transmitted to the stabilizer bar. Due to the stiffness of the stabilizer bar, torsion occurs along its length, which can be described by a torsion angle. The torsion angle of the stabilizer bar is, for example, the difference between the engine-side rotation angle of the stabilizer bar and the wheel-side rotation angle of the stabilizer bar.

[0013] The control process obtains a first setpoint for the stabilizer bar torque and a second setpoint for the stabilizer motor rotation angle. The first and / or second setpoint can be obtained, for example, from a vehicle control unit that determines the respective setpoint based on vehicle motion data to counteract vehicle roll.

[0014] The second target value can be determined from the first target value. For example, the second target value is calculated as the sum of two addends, where the first addend is a rotation angle prevailing at a wheel-side end of the stabilizer bar, and the second addend results from dividing the first target value by a stiffness of the bar material and multiplying the intermediate result by a gear ratio.

[0015] The second setpoint is limited based on the first setpoint. This ensures that the second setpoint does not exceed an upper threshold determined based on the first setpoint.

[0016] The second setpoint is introduced as a reference input into a control loop. The control loop then uses this second setpoint as the target value for the motor rotation angle in the stabilizer motor, so that the actual motor rotation angle closely matches the determined second setpoint. As explained below, the second setpoint can be entered into the control loop after it has been limited. Alternatively, the second setpoint can be limited in the control loop only after it has been entered.

[0017] By limiting the second setpoint, it is possible to avoid, or at least reduce the probability of, a high bar torque requiring a simultaneously high travel speed of the stabilizer motor. This reduces the risk of the stabilizer motor, especially a permanently excited synchronous motor integrated within it, operating outside a defined, regular operating range. Such an operating range would lead to unstable position control of the stabilizer and consequently to a failure of the active roll stabilization system.

[0018] Advantageous designs and further developments are specified in the subclaims.

[0019] According to one embodiment, to limit the change in the second setpoint, it is compared with a predefined threshold, whereby the obtained change in the second setpoint is replaced by the predefined threshold if the obtained change in the second setpoint is greater than the predefined threshold.

[0020] Preferably, the obtained second setpoint remains unchanged if it is equal to or less than the predefined threshold. This measure enables a particularly effective and controllable limitation of the motor rotation angle or motor rotation speed.

[0021] According to another embodiment, the predefined threshold is determined from a dependence of the stabilizer motor's motor torque on the motor rotational speed, obtained from characterizing the stabilizer motor.

[0022] The relationship can be derived, for example, from an engine characteristic curve in which the engine torque is shown as a function of the engine speed. Preferably, this function is presented in a Cartesian coordinate diagram or in a table. Alternatively, the relationship can be derived from an inverted engine characteristic curve, which contains an inverse function of the above function. Because the engine characteristic curve of the stabilizer motor is readily available, the aforementioned relationship can be easily obtained. The method according to the invention is therefore comparatively inexpensive.

[0023] According to a further embodiment, the method also includes determining a motor rotational speed from the dependency that corresponds to the motor torque which corresponds to the first setpoint value as the predefined threshold.

[0024] The first target value for the motor torque is therefore initially assumed, and the corresponding motor speed is determined according to the relationship described above. This allows for a precise determination of the predefined threshold, making the limitation of the second target value particularly effective. This increases the stabilizer's positional stability.

[0025] According to another embodiment, the limited second setpoint is entered into the control loop as a reference variable.

[0026] This measure has the advantage that the limitation of the motor rotation angle or motor rotation speed is introduced into the control chain at an early stage, thus achieving greater robustness in the stabilizer's position control. Limiting the second setpoint in this case refers both to limiting the obtained second setpoint itself before it is fed into the controlled system, and to limiting an intermediate value derived from the obtained second setpoint, such as the gradient of the motor rotation angle or the speed of the stabilizer motor.

[0027] According to another embodiment, the second setpoint is limited within the control loop after being entered into it.

[0028] Limiting the second setpoint in this case includes both the case where the entered second setpoint itself is directly limited in the controlled system, and the case where an intermediate value derived from the entered second setpoint is limited.

[0029] Exemplary embodiments are now described by way of example and with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of an active roll stabilizer according to one embodiment; Fig. 2 a schematic representation of a control device according to one embodiment; and Fig. 3 A schematic representation of a controlled system according to one embodiment.

[0030] In the figures, identical reference symbols refer to identical or functionally similar reference parts. The relevant reference parts are identified in each figure.

[0031] Fig. Figure 1 shows a schematic representation of an active roll stabilizer 30, in particular an active electromechanical roll stabilizer. The roll stabilizer 30 has two stabilizer bars 32, which are preferably designed as tubes. The two stabilizer bars 32 are each attached at a mounting point 40 at one outer end to a wheel of a vehicle ( Fig. 3-4) can be attached. At one inner end, the stabilizer bars 32 are connected to a stabilizer motor 36 (see Fig. 3) of the roll stabilizer 30, wherein the stabilizer motor 36 is arranged in a stabilizer housing 34. Two stabilizer bearings 38 also serve to fasten the roll stabilizer 30.

[0032] The roll stabilizer 30 further comprises a control device 10. The control device 10 preferably serves to determine a setpoint for the rotation angle of the stabilizer motor 36 and to implement this setpoint in the stabilizer motor 36 by means of a control procedure. Fig. Figure 2 shows a schematic representation of the control device 10. The control device 10 comprises a first signal input 12 for obtaining a first setpoint of a rod torque of the stabilizer rod 32, which is to be driven by the stabilizer motor 36. The control device 10 further comprises a second signal input 14 for obtaining a second setpoint of a motor rotation angle of the stabilizer motor 36. The second setpoint can be determined based on the first setpoint, as already described above. The control device 10 also comprises a third signal input 16 for obtaining a predetermined relationship between a motor torque and a motor rotational speed. The predetermined relationship can be derived from a characterization of the stabilizer motor 36. Preferably, the predetermined relationship is derived from a motor characteristic curve, as already described above.

[0033] The control device 10 additionally includes a limiting unit 18, by means of which the second setpoint is limited based on the first setpoint. For example, the limiting unit 18 determines, from the obtained, predetermined relationship, a motor rotational speed corresponding to a motor torque, where the motor torque has the value of the first setpoint of the rod torque. This motor rotational speed is used as the permissible maximum to limit the obtained second setpoint. Preferably, the maximum is further processed as a limited second setpoint and input into a control loop 20 of the control device 10 as a reference input if the second setpoint is greater than or equal to the maximum.

[0034] Otherwise, the obtained second setpoint is processed further without change and entered into the control loop 20.

[0035] Fig. Figure 3 shows a schematic representation of an exemplary control loop 20. According to one embodiment, the second setpoint of the motor rotation angle, φ, is limited as described above. Soll,Motor , fed to a first comparator 202. Simultaneously, an actual value of the motor rotation angle, φ, is recorded. Ist,Motor , fed to the first comparator 202. The first comparator 202 compares the two input values ​​and, if a difference between them is detected that exceeds a predefined threshold, forwards the second setpoint to a position control unit 204. The position control unit 204, which may include the first comparator 202, determines φ from the limited second setpoint. Soll,Motor a third target value for an engine speed, ω Soll,Motor A second comparator 206 compares the third setpoint with an actual value of the engine speed, ω, obtained from the stabilizer motor 36. Ist,Motor, and forwards the third actual value to a speed control unit 208 if a difference between the compared quantities exceeds a further predefined threshold. The speed control unit 208 determines the third setpoint ω from the third target value. Soll,Motor a fourth target value of the engine torque, τ Soll,Motor , and forwards this to a torque control unit 210. The torque control unit 210 determines several, preferably three, currents from the fourth setpoint and supplies these to a DC-AC converter (inverter) 212. Based on the supplied currents, the inverter 212 generates a multiphase, preferably three-phase, alternating current I AC and feeds this into the stabilizer motor 36.

[0036] According to an alternative embodiment, the limitation of the second setpoint does not take place before the controlled system 20, but within it. As in Fig.As shown in dashed lines in Figure 3, the limiting unit 19 can be arranged between the position control unit 204 and the speed control unit 206 instead of in front of the first comparator 202. In this case, instead of a limited second setpoint for the motor rotation angle, an unlimited second setpoint is supplied to the first comparator 202. The limiting unit 19 receives a setpoint for the motor speed ω as input. Soll,Motor from the speed control unit 206 and outputs a limited setpoint for the motor speed. In this embodiment, a limit is therefore imposed based on the second setpoint. Reference sign 10 Control unit 12 first signal input 14 second signal input 16 third signal input 18,19 Limiting unit 20 Control section 202 first comparator 204 Position control unit 206 second comparator 208 Speed ​​control unit 210 Torque control unit 212 Inverter 30 active roll stabilizer 32 Stabilizer bar 34 Stabilizer housings 36 Stabilizer motor / stabilizer actuator 38 stabilizer bearings 40 Mounting point / connecting rod

Claims

[1] Method for actively stabilizing the roll of a vehicle by means of a roll stabilizer (30), wherein the roll stabilizer (30) comprises a stabilizer bar (32), a stabilizer housing (34) and a stabilizer motor (36) arranged in the stabilizer housing (34), such that the stabilizer bar (32) is connected at a first end to a wheel of the vehicle and is rotatably mounted at a second end by means of the stabilizer motor (36), the method comprising: - Obtaining an initial setpoint value of a rod torque of the stabilizer bar (32); - Obtaining a second setpoint of a motor rotation angle of the stabilizer motor (36); - Limiting the second setpoint based on an absolute value and / or a gradient of the first setpoint; - Inputting the second setpoint into a control loop (20) as a reference variable. [2] Method according to claim 1, wherein to limit the second setpoint, it is compared with a predefined threshold, wherein the obtained second setpoint is replaced by the predefined threshold if the obtained second setpoint is greater than the predefined threshold. [3] Method according to claim 2, wherein the predefined threshold is determined from a dependence of a motor torque of the stabilizer motor (36) on the motor rotational speed obtained from characterization of the stabilizer motor (36). [4] Method according to any one of claims 1 to 3, wherein the limited second setpoint is entered as a reference variable into the control system (20). [5] Method according to any one of claims 1 to 3, wherein the second setpoint is limited in the control system (20) after input. [6] Control device (10) for active roll stabilization of a vehicle by means of an active roll stabilizer (30), wherein the control device (10) is configured to carry out the method according to one of the preceding claims. [7] Active roll stabilizer (30) comprising a stabilizer bar (32), a stabilizer housing (34) and a stabilizer motor (36) arranged in the stabilizer housing (34), such that the stabilizer bar (32) is connected at a first end to a wheel of the vehicle and is rotatably mounted at a second end by means of the stabilizer motor (36), the roll stabilizer (30) further comprising a control device (10) according to claim 6. [8] Vehicle comprising an active roll stabilizer (30) according to claim 7, wherein the active roll stabilizer (30) is mounted on at least one wheel of the vehicle. [9] Computer program product comprising instructions which, when the program is executed by a computer, cause it to execute the method according to claim 1. [10] Computer-readable storage medium on which the computer program product according to claim 9 is stored. [11] Data carrier signal that transmits the computer program product according to claim 9.

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