DE102016223332A1 - Method for driving a steering device of a vehicle, control unit and steering device - Google Patents

Abstract

The invention relates to a method for driving a steering device (106) of a vehicle (100), wherein the steering device (106) is designed to individually adjust a left wheel (110) and a right wheel (114) of the vehicle (100). For this purpose, a driving state information (116) representing a driving state of the vehicle (100) and a wheel target position (118) of the left wheel (110) and the right wheel (114) are read. Then, using the running state information (116) and the target wheel position (118), a left deviation value by which a wheel position of the left wheel (110) should deviate from the wheel target position (118) or, additionally or alternatively, a right deviation value around the wheel a wheel position of the right wheel (114) should deviate from the desired wheel position (118) determined. Finally, using the left and right deviation values, respectively, a drive signal (120) for driving the steering device (106) is provided to set the left wheel (110) in a wheel target position corrected by the left deviation value and the right wheel (114) in FIG to set a wheel setpoint corrected by the right deviation value.

Description

The present invention relates to a method for driving a steering device of a vehicle, to a corresponding control device and to a corresponding steering device.

For example, a steering function of a vehicle can calculate a setpoint angle for actuators of a rear-axle steering system with wheel-specific control on the basis of vehicle measured variables. As a rule, an identical position is always output for both actuators in order to maintain an on-vehicle toe adjustment in all circumstances.

Against this background, the present invention provides an improved method for driving a steering device of a vehicle, an improved control device and an improved steering device according to the main claims. Advantageous embodiments will become apparent from the dependent claims and the description below.

• Einlesen einer einen Fahrzustand des Fahrzeugs repräsentierenden Fahrzustandsinformation und einer Radsollposition des linken Rads und des rechten Rads;
• Ermitteln eines linken Abweichungswertes, um den eine Radposition des linken Rads von der Radsollposition abweichen soll, und/oder eines rechten Abweichungswertes, um den eine Radposition des rechten Rads von der Radsollposition abweichen soll, unter Verwendung der Fahrzustandsinformation und der Radsollposition; und
• Bereitstellen eines Ansteuersignals zum Ansteuern der Lenkeinrichtung unter Verwendung des linken Abweichungswertes und/oder des rechten Abweichungswertes, um das linke Rad in eine um den linken Abweichungswert korrigierte Radsollposition zu stellen und/oder das rechte Rad in eine um den rechten Abweichungswert korrigierte Radsollposition zu stellen.

A method for driving a steering device of a vehicle is presented, wherein the steering device is designed to individually adjust a left wheel and a right wheel of the vehicle, the method comprising the following steps:

• Reading a driving state information representing a driving state of the vehicle and a wheel target position of the left wheel and the right wheel;
• Determining a left deviation value by which one wheel position of the left wheel should deviate from the target wheel position, and / or a right deviation value by which one wheel position of the right wheel should deviate from the target wheel position, using the running condition information and the wheel target position; and
• Providing a drive signal for driving the steering device using the left deviation value and / or the right deviation value to set the left wheel in a wheel target position corrected by the left deviation value and / or to set the right wheel in a wheel target position corrected by the right deviation value.

The steering device may include, for example, at least two steering actuators associated with a front or rear axle of the vehicle, wherein a left steering actuator may be coupled to the left wheel and a right steering actuator may be coupled to the right wheel. The left and right wheels may be opposed wheels on the same axle. Driving state information may be taken to mean vehicle measured variables such as, for example, a speed, a steering wheel angle, a brake pressure, a brake pedal position, a transverse or longitudinal acceleration or a yaw rate of the vehicle. A wheel target position may be understood to mean, for example, a target position of the left wheel that coincides with a target position of the right wheel insofar as the desired positions of the left and right wheels are symmetrical with respect to a longitudinal axis of the vehicle. In other words, the toe angles or steering angles on the left and right wheels have the same amount. By the Radsollposition can be set, for example, a predetermined toe or toe of the vehicle. Depending on the embodiment, different deviation values for the left-hand wheel and the right-hand wheel can be determined in the step of determining, for example, when cornering, a turn-wheel stronger than a turn-out wheel.

The approach described here is based on the recognition that wheel-specific steering angles for the two wheels can be set by correcting a predetermined desired wheel position for both wheels of a steerable vehicle axle as a function of a current driving state with little computational effort. For example, this can be an asynchronous position control for a rear axle steering with two-plate system can be realized, can be specified by the functionally different positions for each wheel, such as when cornering at large angles to a so-called Ackermann compensation for taking into account the different radii of the curve inner and outer curve wheel perform.

Furthermore, this allows a dynamic change of a Vorspureinstellung. For example, when driving straight ahead, a maximum speed can be increased by reducing the toe-in, or at constant speed the fuel or energy consumption can be reduced. During braking, increasing the toe can shorten the braking distance of the vehicle.

According to an embodiment, in the step of reading, a speed, a steering angle, a steering wheel angle, a brake pressure, a brake pedal position, a lateral acceleration, a longitudinal acceleration or a yaw rate of the vehicle, or a combination of at least two of said quantities may be read as the driving state information. As a result, the left or right deviation value can be determined very accurately.

According to a further embodiment, in the step of determining one of the right Deviation value deviating value can be determined as the left deviation value. As a result, depending on the driving condition, different desired wheel positions for the left and the right wheel can be determined.

It is also advantageous if in the step of reading a gauge of the vehicle is read. At this time, in a step of determining using the driving state information and the track width, a radius deviation value of a deviation between a steering radius of the left wheel and a steering radius of the right wheel may be determined. Accordingly, in the step of determining at least one of the two deviation values can be determined using the radius deviation value. This embodiment enables the calculation of an asymmetric offset between left and right wheels.

Furthermore, in the step of providing, the drive signal may be provided to increase a toe of the vehicle when braking the vehicle. Additionally or alternatively, the drive signal may be provided to reduce the toe in straight traveling of the vehicle at a constant speed. As a result, the driving behavior of the vehicle can be improved.

According to another embodiment, an asynchronous value representing a deviation between an adjusting speed of the left wheel and an adjusting speed of the right wheel may be read in the step of reading in. In a step of comparing, the asynchronous value may be compared to a minimum threshold, a maximum threshold, and a mid threshold between the minimum threshold and the maximum threshold. In the providing step, the drive signal may be provided to equalize the left wheel speed and the right wheel speed by braking a steering actuator coupled to the left wheel or, additionally or alternatively, a steering actuator of the steering device coupled to the right wheel the asynchronous value is between the mid-threshold and the maximum threshold. A minimum threshold value, a maximum threshold value and a medium threshold value can each be understood as meaning a different value of a deviation of a radist position from a desired wheel position of a single wheel of the vehicle. In this case, a threshold value can be understood as an intervention threshold in which, for example, an automatic intervention of a vehicle control to correct the individual wheel positions takes place. The intervention threshold may also be referred to as the deviation threshold. Through this embodiment, it is possible to react particularly quickly to errors in the steering behavior.

This method can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit.

The approach presented here also creates a control unit which is designed to execute, to control or to implement the steps of a variant of a method presented here in corresponding devices. Also by this embodiment of the invention in the form of a control device, the object underlying the invention can be achieved quickly and efficiently.

In the present case, a control device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The control unit may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based embodiment, the interfaces can be part of a so-called system ASIC, for example, which contains various functions of the control unit. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules.

In an advantageous embodiment, the control unit is used to control the vehicle. For this purpose, the control unit can access, for example, sensor signals such as acceleration, pressure, steering angle or environmental sensor signals. The control takes place via actuators such as brake or steering actuators or an engine control unit of the vehicle.

• einer Lenkeinrichtung, die ausgebildet ist, um ein linkes Rad und ein rechtes Rad des Fahrzeugs einzeln zu verstellen; und
• einem Steuergerät gemäß einer vorstehenden Ausführungsform.

Furthermore, the approach presented here creates a steering device for a vehicle with the following features:

• a steering device configured to individually adjust a left wheel and a right wheel of the vehicle; and
• a control device according to a preceding embodiment.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of Method according to one of the embodiments described above, in particular when the program product or program is executed on a computer or a device.

• 1 eine schematische Darstellung eines Fahrzeugs mit einer Lenkvorrichtung gemäß einem Ausführungsbeispiel;
• 2 ein Ablaufdiagramm einer radindividuellen Ansteuerung einer Fahrzeuglenkung;
• 3 ein Ablaufdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel;
• 4 ein Diagramm zur schematischen Darstellung eines zeitlichen Verlaufs einer Radpositionsabweichung bei einer radindividuellen Ansteuerung einer Fahrzeuglenkung;
• 5 ein Diagramm zur schematischen Darstellung eines zeitlichen Verlaufs einer Radpositionsabweichung bei Verwendung eines Verfahrens gemäß einem Ausführungsbeispiel;
• 6 eine schematische Darstellung eines Steuergeräts gemäß einem Ausführungsbeispiel; und
• 7 ein Ablaufdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel.

The invention will be described by way of example with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a vehicle with a steering apparatus according to an embodiment;
• 2 a flowchart of a wheel-individual control of a vehicle steering;
• 3 a flowchart of a method according to an embodiment;
• 4 a diagram for schematically illustrating a time course of a wheel position deviation in a wheel-individual control of a vehicle steering system;
• 5 a diagram for schematically illustrating a time course of a wheel position deviation when using a method according to an embodiment;
• 6 a schematic representation of a control device according to an embodiment; and
• 7 a flowchart of a method according to an embodiment.

In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and similarly acting, wherein a repeated description of these elements is omitted.

1 shows a schematic representation of a vehicle 100 with a steering device 102 according to an embodiment. The steering device 102 includes a controller 104 and a steering device 106 according to this embodiment, a left steering actuator 108 to put a left wheel 110 of the vehicle 100 , here a curve-inside wheel with a steering angle φ _i , and a right steering actuator 112 to make a right wheel 114 of the vehicle 100 , here an outside wheel with a steering angle φ _a , having. By means of the two steering actuators 108 . 112 is the steering device 106 capable of both wheels 110 . 114 independent of each other, that is to say on a wheel-by-wheel basis. The control unit 104 is designed to provide driving condition information 116 and read in a desired wheel position 118, for example via an interface to various sensors of the vehicle 100 , The wheel nominal position 118 represents one for both wheels 110 . 114 identical wheel position, for example with respect to a longitudinal axis of the vehicle 100 , At the driving condition information 116 Depending on the exemplary embodiment, these are values such as speed, steering angle, steering wheel angle, brake pressure, brake pedal position, lateral acceleration, longitudinal acceleration or yaw rate of the vehicle 100 , The control unit 104 uses the driving condition information 116 and the wheel nominal position 118 to each one deviation of the left wheel 110 from the wheel nominal position 118 or a target deviation of the right wheel 114 from the wheel nominal position 118 to investigate. Depending on the driving condition, the control unit determines 104 Here, different target deviations for the left and the right wheel, so that an asymmetric adjustment of the two wheels 110 . 114 results, for example, when cornering for so-called Ackermann compensation, as in 1 is indicated by way of example. Depending on the for the two wheels 110 . 114 Determined target deviations provides the control unit 104 a corresponding drive signal 120 for driving the two steering actuators 108 . 112 ready to get the two wheels 110 . 114 each in a corrected by the respective nominal deviation Radsollposition.

According to one embodiment, the controller reads 104 in addition to the driving condition information 116 and the wheel target position 118 a gauge 122 of the vehicle 100 one. By means of the gauge 122 determines the control unit 104 a deviation of a steering radius RV _i the left wheel 110 from a steering radius RV _a the right wheel 114 and uses these to the respective nominal deviation of the two wheels 110 . 114 from the wheel nominal position 118 to determine.

2 shows a flowchart of a wheel-individual control of a vehicle steering system with a left actuator 202 and a right actuator 204 , These are from a steering control unit 206 Vehicle measurements 208 read in and to calculate a Radsollposition 210 used for both wheels of the vehicle. The two actuators 202 . 204 serve to rotate the left and right wheels of the vehicle using the desired wheel position 210 each in the same position.

3 shows a flowchart of a method according to an embodiment. The procedure 300 for driving a steering device of a vehicle, for example, using a control device, as described above with reference to 1 is described. It is in one step 310 using vehicle measurements 312 the wheel nominal position 118 calculated. In a subsequent step 320 is using the wheel set position 118 and the driving status information 116 calculates a wheel offset for the left and right wheels. This is done in one step 330 the activation of the left steering actuator 108 depending on the step 320 Calculated wheel setpoint including offset left and the control of the right steering actuator 112 depending on the step 320 Calculated wheel setpoint including offset to the right.

For example, the driving status information 116 and the vehicle measurements 312 represent similar but measured at different times measured variables.

4 shows a diagram for schematically illustrating a time course of a wheel position deviation in a wheel-individual control of a vehicle steering. Shown is a curve 400 , which reflects the wheel position deviation as a function of time. Furthermore, a first intervention threshold 402 , a second intervention threshold 404 as well as a security goal 406 each drawn as a horizontal line, the second intervention threshold 404 between the first intervention threshold 402 and the security goal 406 lies. An error response time 408 is indicated by two vertical lines.

5 shows a diagram for schematically illustrating a time profile of a wheel position deviation in a wheel-individual control using a method according to an embodiment, such as a method, as described previously with reference to 3 is described. Similar to in 4 is the course of the wheel position deviation through the curve 400 representing the wheel position deviation as a function of time. In contrast to 4 is in addition to the intervention thresholds 402 . 404 a third intervention threshold 502 drawn as a horizontal line. In this case, the first intervention threshold 402 represents a minimum threshold, the intervention threshold 404 a maximum threshold and the intervention threshold 502 one between the two intervention thresholds 402 . 404 lying middle threshold. An area of a functionally used deviation is a hatched area below the curve 400 shown. The curve 400 shows in comparison to 4 an overall flatter course.

6 shows a schematic representation of a control device 104 according to an embodiment, such as one above based on 1 described control unit. The control unit 104 includes a read-in unit 610 for reading in the driving state information 116 and the wheel target position 118 , A discovery unit 620 is configured to operate using the driving condition information 116 and the wheel target position 118 a left deviation value representing the target deviation of the left wheel 622 or, depending on the exemplary embodiment additionally or alternatively, a right deviation value representing the nominal deviation of the right wheel 624 to identify and send this to a deployment unit 630 of the control unit 104 forward. The delivery unit 630 is configured to use at least one of the two deviation values 622 . 624 the drive signal 120 to generate and send to an interface to the steering actuators of the steering device of the vehicle.

According to one embodiment, the read-in unit 610 formed to further an asynchronous value 632 read in, which represents a deviation between an actuating speed of the left steering actuator and an actuating speed of the right steering actuator. An optional comparison unit 640 is designed to be asynchronous 632 from the reading unit 610 to receive and to compare with the minimum threshold, the maximum threshold and the middle threshold. As a result of the comparison gives the comparison unit 640 a corresponding comparison value 642 to the delivery unit 630 out, with the provisioning unit 630 is formed to the drive signal 120 using the comparison value 642 to provide for decelerating a faster of the two steering actuators when the asynchronous value 632 between the middle threshold and the maximum threshold.

7 shows a flowchart of a method 700 according to an embodiment. In contrast to 3 includes the method 700 according to 7 one step 710 in which the driving state information and the wheel target position are read. In step 720 Then, using the driving state information and the desired wheel position, either the left deviation value, previously also called wheel offset left, or the right deviation value, also called right wheel offset, is determined, or both the left deviation value and the right deviation value are determined. Finally, in one step 730 the drive signal for driving the steering device using at least one in the step 720 provided deviation value.

Hereinafter, various embodiments of the approach presented here will be described again in other words.

The method for driving the steering device is based, for example, on an algorithm that provides a synchronous angle specification as well as vehicle variables such as vehicle speed, steering wheel angle, brake pressure, lateral acceleration, longitudinal acceleration, yaw rate or others has suitable measured variables as inputs and uses these to calculate two different angle specifications for left and right wheel based on the driving situation.

Depending on the exemplary embodiment, the following partial calculations are used for this purpose.

On the one hand, for example, a function is realized which calculates a radius deviation between the left and right wheels on the basis of a vehicle two-track model with a current front axle and rear axle steering angle and the track width. Based on the radius deviation is then in step 720 a particular asymmetric offset for left and right wheel determined, calculated, for example. Furthermore, a function can be implemented in the step 720 determined on the basis of the brake pressure, the longitudinal acceleration or the brake pedal position a particular symmetrical offset for left and right wheel, calculated, for example. This is done, for example, on the basis of a characteristic which has the above variables as input and a desired offset as output.

Additionally or alternatively, to realize another function in step 720 calculated on the basis of the vehicle speed in particular a symmetrical offset for left and right wheel. This takes place again, for example, on the basis of a characteristic curve which has the vehicle speed as the input and the setpoint offset as the output.

These functions may be in contradiction to the requirement for safety reasons, according to which the deviation of the wheel positions should not exceed a certain threshold, also referred to above as the safety target. The functionally motivated asynchronisms of the positions should therefore not lead to robustness losses of the system. Therefore, the functional part of the asynchronism in the synchronization of the wheels should be considered, such as the in the 4 and 5 shown first intervention threshold 402 is increased. Since the safety goals regarding asynchrony can not be reduced, the available error response time is shortened. The available fault reaction time is limited by design, which can lead to the required fault response time can not be met.

For the monitoring of the synchronicity, an improvement for shortening the error reaction time is now proposed. For this purpose, if an asynchronism at the in 5 shown third engagement threshold 502 below the second intervention threshold 404 is detected, the leading steering actuator or actuator actively braked. This is done either via a reduction of the permissible engine torque or via active braking of the steering actuator. The threshold for this function is between the two intervention thresholds 402 . 404 , As the speed increases until reaching the second intervention threshold 404 reduces the available error response time, as does this 5 is apparent. In addition, for example, a function is implemented which checks that the wheel positions on the left and right are identical. For deviating wheel position above the first intervention threshold 402 The speed of the leading steering actuator is reduced until the wheels behave back in sync position. Nevertheless, the position deviation approaches, for example, due to a fault in the system, the maximum allowable deviation, ie the safety target 406 , so from the second intervention threshold 404 both steering actuators locked via a locking mechanism before the maximum allowable deviation in terms of the safety objective 406 is reached.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, this can be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment, either only the first Feature or only the second feature.

LIST OF REFERENCE NUMBERS

100

vehicle

102

steering device

104

control unit

106

steering device

108

left steering actuator

110

left wheel

112

right steering actuator

114

right wheel

116

Driving condition information

118

Radsollposition

120

control signal

122

gauge

φ _i

steering angle

φ _a

steering angle

RV _i

turning radius

RV _a

turning radius

202

left actuator

204

right actuator

206

Steering control unit

208

Vehicle measurements

210

Radsollposition

300

method

310

Step of calculating

312

Vehicle measurements

320

Step of determining

330

Step of driving

400

Curve

402

first intervention threshold

404

second intervention threshold

406

security target

408

Fault response time

502

third intervention threshold

610

reading unit

620

determining unit

622

left deviation value

624

right deviation value

630

Providing unit

632

Asynchronitätswert

640

comparing unit

642

comparison value

700

method

710

Step of reading in

720

Step of determining

730

Step of providing

Claims (10)

A method (300; 700) for driving a steering device (106) of a vehicle (100), wherein the steering device (106) is configured to individually adjust a left wheel (110) and a right wheel (114) of the vehicle (100) wherein the method (300) comprises the steps of: Reading in (710) a driving state information (116) representing a driving state of the vehicle (100) and a wheel target position (118) of the left wheel (110) and the right wheel (114); Determining (320; 720) a left deviation value (622) by which one wheel position of the left wheel (110) should deviate from the wheel target position (118) and / or a right deviation value (624) by one wheel position of the right wheel ( 114) should deviate from the target wheel position (118) using the driving condition information (116) and the target wheel position (118); and Providing (730) a drive signal (120) for driving the steering device (106) using the left deviation value (622) and / or the right deviation value (624) to shift the left wheel (110) to a left deviation value (622). to provide corrected wheel target position and / or to place the right wheel (114) in a desired wheel position corrected by the right deviation value (624). Method (300; 700) according to Claim 1 in which, in the step of read-in (710), a speed and / or a steering angle and / or a brake pressure and / or a brake pedal position and / or a lateral acceleration and / or a longitudinal acceleration and / or a yaw rate of the vehicle ( 100) is read in as the driving condition information (116). Method (300; 700) according to one of the preceding claims, wherein in the step of determining (320; 720) a value deviating from the right deviation value (624) is determined as the left deviation value (622). Method (300; 700) according to one of the preceding claims, wherein in the read-in step (710), a track (122) of the vehicle (100) is read, wherein in a step of determining using the driving condition information (116) and the gauge (122) a radius deviation value of a deviation between a steering radius (RV _i ) of the left wheel (110) and a steering radius (RV _a ) of the right wheel (114) is determined, wherein in the step of determining (320; 720) the left deviation value ( 622) and / or the right deviation value (624) is determined using the radius deviation value. Method (300; 700) according to one of the preceding claims, wherein in the step of providing (730) the drive signal (120) is provided to increase and / or during toe-in of the vehicle (100) during braking of the vehicle (100) Driving straight ahead of the vehicle (100) at a constant speed. Method (300; 700) according to one of the preceding claims, wherein in the read-in step (710) an asynchronicity value (632) representing a deviation between an actuating speed of the left-hand wheel (110) and an actuating speed of the right-hand wheel (114) is read in, wherein in a step of comparing (640) the asynchronous value (632) is compared to a minimum threshold, a maximum threshold and a mid threshold between the minimum threshold and the maximum threshold, wherein in the step of providing (730) the drive signal (120) is provided the speed of the left wheel (110) and the speed of the right wheel (114) by braking a steering actuator (108) coupled to the left wheel (110) and / or a steering actuator (112) coupled to the right wheel (114), if the asynchronous value (632) between the center threshold and the Maximum threshold is. A controller (104) having units (610, 620, 630, 640) configured to execute and / or drive the method (300) of any one of the preceding claims. A steering device (102) for a vehicle (100), the steering device (102) comprising: a steering device (106) configured to engage a left wheel (110) and a right wheel (114) of the vehicle (100 ) individually; and a controller (104) according to Claim 7 , A computer program configured to execute the method (300; 700) according to one of Claims 1 to 6 execute and / or control. Machine-readable storage medium on which the computer program is based Claim 9 is stored.

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