DE102019202188A1 - Control device and method as well as computer program product - Google Patents

Abstract

A control method for a vehicle (50) comprising obtaining a speed of the vehicle (50); Establishing a target value for a steering angle of the vehicle (50) based on the determined speed; Generating a control signal for adapting an actual value of the steering angle to the specified target value; and outputting the generated control signal to a steering device (52) of the vehicle (50).

Description

TECHNICAL AREA

The present invention relates to the field of off-road vehicles such as utility vehicles and / or land vehicles, in particular off-road vehicles that drive autonomously or partially autonomously.

TECHNICAL BACKGROUND

In off-road vehicles such as tractors, purely mechatronic steering systems that are operated electro-hydraulically or electro-motor are not very common. This is due to the fact that previous steering systems have been implemented mechanically (e.g. in the form of steering columns or steering rods) or hydraulically (e.g. in the form of hydraulic steering blocks).

For mechatronic steering systems, especially main or additional steering systems, there are high safety requirements, e.g. in connection with the standards ECE-R79 and ISO 10998. In addition, additional hazards are to be expected, since not all failures that can lead to dangerous malfunctions can be avoided constructively.

Furthermore, in the known steering systems, the degree of malfunctions with regard to hardness and tenacity cannot be determined in a simple manner. In many cases this leads to a restriction of the functional dynamics of the steering systems. The availability of the steering systems is also reduced due to incorrectly identified problems (False Positive).

The present invention is therefore based on the object of increasing the controllability of malfunctions in steering systems, in particular mechatronic steering systems.

The object is achieved by a control device, a control method, a computer program product, a computer-readable storage medium and a data carrier signal according to the independent claims.

The device for controlling the vehicle can be, for example, an electronic control or regulating unit (ECU = Electronic Control Unit), an electronic control or regulating module (ECM = Electronic Control Module) or a control / regulating unit for autonomous Acting driving (e.g. an "autopilot"). The control device can be attached to the vehicle or outside or partially outside the vehicle. For example, the control device can be part of a central monitoring device for the agricultural area, the vehicle being an agricultural machine. Alternatively, the control device can be part of a central monitoring device for a port area, the vehicle being a vehicle for receiving and / or storing swap bodies. The communication between the control device or the central monitoring device and the vehicle can take place wirelessly, for example via BlueTooth, infrared, near-field communication (NFC), radio, Internet, intranet, cloud systems and / or wired systems.

The speed of the vehicle is preferably determined by a motion sensor system and forwarded to the control device. The motion sensor system can be attached to the vehicle, or alternatively to a surrounding area and / or the central monitoring device. For example, the motion sensor system is a speed sensor or an odometry sensor, such as a wheel rotation sensor. Alternatively or in addition, radar sensors, lidar sensors, cameras and / or ultrasonic sensors can also be used. It is also conceivable to determine the speed using a navigation satellite system such as the Global Navigation Satellite System (GNSS).

Based on the determined speed of the vehicle, a setpoint value for a steering angle of the vehicle is determined by means of the evaluation unit. The evaluation unit can comprise a central processing unit (CPU) or a graphic processing unit (GPU). Alternatively, the evaluation unit can be an ECU or an ECM. In this case, the control device is a device / arrangement that is superordinate to the ECU or the ECM. The evaluation unit thus relates the target value of the steering angle to the vehicle speed. The steering angle can be determined by detecting the steering wheel angle. At higher vehicle speeds, large steering angles should be avoided as these increase the safety risks of the vehicle when maneuvering. In this way, a steering angle that is too high can at least be effectively reduced at higher speeds.

According to the target value of the steering angle determined in this way, a control signal for adapting the actual value of the steering angle to the target value is generated, which is output via the output interface to a vehicle, in particular a steering device of the vehicle. The actual value can be adjusted using a Control loop take place, which is preferably included in the evaluation unit.

As an alternative to the above embodiment, a target value for the rate of change of steering angle (or the acceleration of the steering angle speed) can be determined on the basis of the vehicle speed. This can also reduce the risk that steering the vehicle too quickly at higher speeds will lead to a safety-critical situation or a malfunction of the vehicle.

Advantageous refinements and developments are specified in the subclaims.

According to one embodiment, the method according to the invention further comprises monitoring the actual value and generating a control signal for transferring the vehicle to a safe state when the actual value exceeds the setpoint value.

In this way, a safer state of the vehicle can be ensured in a reliable manner. A tolerance range around the target value can be predefined so that the transfer to the safe state only takes place when the actual value exceeds the tolerance range.

According to a further embodiment, the method according to the invention further comprises determining a steering sustainability value based on a steering angle change rate or its time derivative, and / or determining a steering effect value based on a time derivative of the steering angle change rate.

The steering sustainability value indicates the degree of how sustained a steering movement is at a certain steering angle and is preferably proportional to the rate of change of the steering angle or, alternatively, to its time derivative of the first order, which corresponds to the acceleration of the steering angle. The steering effect value indicates the degree to which a steering movement affects the vehicle kinematics at a certain steering angle, and is preferably proportional to the time derivative of the steering change rate.

According to a further embodiment, the method according to the invention further comprises determining a permissible range for a value pair comprising the steering sustainability value and the steering effect value.

This results in a two-dimensional diagram of steering sustainability values and steering effect values. Such a diagram can be predefined and stored so that the control device according to the invention or the evaluation unit can access the diagram and compare current measured value pairs including a steering sustainability value and an associated steering effect value with the diagram. Two-dimensional permissible and impermissible areas can be defined in the diagram.

According to a further embodiment, the method according to the invention further comprises determining a permissible range for a combination of values comprising the steering sustainability value, the steering effect value and the vehicle speed.

This results in a three-dimensional diagram of steering sustainability values, steering effect values and vehicle speed values. Such a diagram can be predefined and stored so that the control device according to the invention or the evaluation unit can access the diagram and compare current measured value combinations including a steering sustainability value, an associated steering effect value and an associated vehicle speed value with the diagram. Three-dimensional permitted and impermissible areas can be defined in the diagram.

The computer program product according to the invention is designed to be loaded into a memory of a computer and comprises software code sections with which the method steps of the method according to the invention are carried out when the computer program product is running on the computer.

A program belongs to the software of a data processing system, for example an evaluation device or a computer. Software is a collective term for programs and associated data. The complement to software is hardware. Hardware describes the mechanical and electronic alignment of a data processing system. A computer is an evaluation device.

Computer program products generally comprise a sequence of instructions which, when the program is loaded, cause the hardware to carry out a specific method that leads to a specific result. When the program in question is used on a computer, the computer program product produces the inventive technical effect described above.

The computer program product according to the invention is platform independent. That means it can run on any computing platform. The computer program product is preferably executed on an evaluation device according to the invention for detecting the surroundings of the vehicle.

The software code sections are written in any programming language, for example in C or C ++.

The computer-readable storage medium is, for example, an electronic, magnetic, optical or magneto-optical storage medium.

The data carrier signal is a signal which the computer program product from a storage medium on which the computer program product is stored to another entity, for example another storage medium, a server, a cloud system or a data processing facility , transmits.

• 1 eine schematische Darstellung einer Steuervorrichtung gemäß einer Ausführungsform;
• 2 eine schematische Darstellung eines Verfahrens gemäß einer Ausführungsform;
• 3A eine schematische Darstellung eines Reglungsverhaltens des Lenkwinkels in Abhängigkeit von der Fahrzeuggeschwindigkeit;
• 3B eine schematische Darstellung eines Reglungsverhaltens der Lenkwinkeländerungsrate in Abhängigkeit von der Fahrzeuggeschwindigkeit;
• 4A eine schematische Darstellung eines Lenkungsnachhaltigkeitswertes und eines Lenkungsauswirkungswertes über Zeit;
• 4B eine weitere schematische Darstellung eines Lenkungsnachhaltigkeitswertes und eines Lenkungsauswirkungswertes über Zeit;
• 5 ein schematisches Diagramm, in dem der Lenkungsauswirkungswert gegen den Lenkungsnachhaltigkeitswert aufgetragen ist; und
• 6 ein schematisches Diagramm, in dem der Lenkungsauswirkungswert, der Lenkungsnachhaltigkeitswert sowie die Fahrzeuggeschwindigkeit in Abhängigkeit voneinander aufgetragen ist.

Embodiments will now be described by way of example and with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a control device according to an embodiment;
• 2 a schematic representation of a method according to an embodiment;
• 3A a schematic representation of a control behavior of the steering angle as a function of the vehicle speed;
• 3B a schematic representation of a control behavior of the steering angle change rate as a function of the vehicle speed;
• 4A a schematic representation of a steering sustainability value and a steering impact value over time;
• 4B a further schematic representation of a steering sustainability value and a steering effect value over time;
• 5 a schematic diagram in which the steering impact value is plotted against the steering sustainability value; and
• 6th a schematic diagram in which the steering effect value, the steering sustainability value and the vehicle speed are plotted as a function of one another.

In the figures, the same reference numerals relate to the same or functionally similar reference parts. The relevant reference parts are identified in the individual figures.

1 shows a schematic representation of a control device 10 for a vehicle 50 , especially a commercial vehicle such as trucks or agricultural machinery. The vehicle 50 can be a partially or fully automated vehicle. The control device 10 includes an input interface 12 for entering a speed of the vehicle 50 . As in 1 shown as an example, provides a motion sensor system 20th the speed. Alternatively, the speed can be provided by a storage medium, a database or a server or cloud system.

The control device 10 further comprises an evaluation unit 14th , by means of which a target value of a steering angle of the vehicle 50 is determined based on the obtained speed. The evaluation unit is an alternative 14th designed to determine the target value of a rate of change of steering angle on the basis of the vehicle speed obtained. The setpoint value thus takes into account the vehicle speed, which is used to prevent steering angles that are too large or that the steering angle changes too quickly at higher vehicle speeds 50 to avoid.

The control device 10 also includes a signal unit 16 for generating a control signal to the above target value by a steering device 52 of the vehicle 50 to implement. To this end, the control device 10 an output interface 18th to output the generated control signal.

limitiert. Der optimierte Soll-Wert ${\phi }_{Soll}^v$

wird in einem vierten Schritt S4 an die Lenkungseinrichtung 52 des Fahrzeugs 50 zur Implementierung ausgegeben. Die Lenkungseinrichtung 52 erhält das Steuersignal von der Auswerteeinheit 14 und steuert die Lenkung, insbesondere die mechatronische Lenkung, des Fahrzeugs 50 in einem fünften Schritt S5. Der Ist-Wert des Lenkwinkels φ_Ist wird, beispielsweise anhand des Lenkradeinschlags, gemessen und mit Hilfe eines Regelkreises 140 der Auswerteeinheit 14 überwacht. Zum Regelkreis 140 gehört ein Komparator 142, welcher den Ist-Wert des Lenkwinkels φ_Ist mit dem Soll-Wert φ_Soll vergleicht. Beim Überschreiten des Soll-Wertes φ_Soll wird ein Steuersignal in einem Schritt S6 erzeugt, welches dazu dient, das Fahrzeug 50 in einen sichereren Zustand zu überführen. Dazu können Maßnahmen wie Bremsen oder Lenkrichtungsänderung ergriffen werden. Alternativ oder zusätzlich kann beim Unterschreiten des Soll-Wertes φ_Soll ein bestimmter Reglungsparameter des Regelkreises 140, beispielsweise ein P-, I- und/oder D-Parameter einer PID-Reglung, optimiert werden. 2 shows a schematic representation of a method according to an embodiment. In a first step S1 becomes the steering angle φ of the vehicle 50 determined. In a second step S2 a target value φ _{target of} the steering angle φ is assumed. The assumed target value φ is _set in a third step S3 based on the obtained speed v of the vehicle 50 to an optimized target value ${\phi }_{\mathrm{S.}Oll}^v$

limited. The optimized target value ${\phi }_{\mathrm{S.}Oll}^v$

will be in a fourth step S4 to the steering device 52 of the vehicle 50 issued for implementation. The steering device 52 receives the control signal from the evaluation unit 14th and controls the steering, in particular the mechatronic steering, of the vehicle 50 in a fifth step S5 . The actual value of the steering angle φ _actual is measured, for example on the basis of the steering wheel angle, and with the aid of a control loop 140 the evaluation unit 14th supervised. To the control loop 140 belongs to a comparator 142 , which compares the actual value of the steering angle φ _actual with the target value φ _target . When the target value φ _target is exceeded, a control signal is issued in one step S6 generated which serves the vehicle 50 to move to a safer state. For this purpose, measures such as braking or changing the steering direction can be taken. Alternatively or additionally, a certain control parameter of the control loop can be used when the target value φ _{target is} not reached 140 , for example a P, I and / or D parameter of a PID control, can be optimized.

Although not in 2 shown, the method works equally for the case that instead of the steering angle φ its time derivative of the first order <p is used as the controlled variable.

des Fahrzeugs 50 in Abhängigkeit von der Fahrzeuggeschwindigkeit v. Bei niedrigen Geschwindigkeiten ist ein größerer Lenkwinkel in der Regel unkritisch, da keine sicherheitskritische Situation bzw. eine Fehlfunktion des Fahrzeugs 50 tendenziell zu befürchten ist. Daher ist der optimierte Soll-Wert ${\phi }_{Soll}^v$

in diesem Fall größer. Im Diagramm ist dieses Verhalten für positive und negative Geschwindigkeiten, die zwei einander entgegengesetzten Fahrtrichtungen entsprechen, gezeigt. Bei höheren Geschwindigkeiten des Fahrzeugs 50 hingegen ist mit erhöhten Sicherheitsrisiken beim Lenken bzw. Rangieren zu rechnen. Daher ist der optimierte Soll-Wert ${\phi }_{Soll}^v$

in diesem Fall kleiner. 3A shows a schematic diagram to illustrate the behavior of the optimized target value of the steering angle ${\phi }_{\mathrm{S.}Oll}^v$

of the vehicle 50 depending on the vehicle speed v. At low speeds, a larger steering angle is generally not critical, since there is no safety-critical situation or a malfunction of the vehicle 50 tends to be feared. Hence the optimized target value ${\phi }_{\mathrm{S.}Oll}^v$

larger in this case. This behavior is shown in the diagram for positive and negative speeds, which correspond to two opposite directions of travel. At higher vehicle speeds 50 however, increased safety risks when steering or maneuvering are to be expected. Hence the optimized target value ${\phi }_{\mathrm{S.}Oll}^v$

in this case smaller.

des Fahrzeugs 50 in Abhängigkeit von der Fahrzeuggeschwindigkeit v. Bei niedrigen Geschwindigkeiten ist ein größerer Lenkwinkel in der Regel unkritisch, da keine sicherheitskritische Situation bzw. Fehlfunktion des Fahrzeugs 50 tendenziell zu befürchten ist. Daher ist der optimierte Soll-Wert ${\dot{\phi }}_{Soll}^v$

in diesem Fall größer. Im Diagramm ist dieses Verhalten für positive und negative Geschwindigkeiten, die zwei einander entgegengesetzten Fahrtrichtungen entsprechen, gezeigt. Bei höheren Geschwindigkeiten des Fahrzeugs 50 hingegen ist mit erhöhten Sicherheitsrisiken beim Lenken bzw. Rangieren zu rechnen. Daher ist der optimierte Soll-Wert ${\dot{\phi }}_{Soll}^v$

in diesem Fall kleiner. 3B shows a schematic diagram to illustrate the behavior of the optimized target value of the rate of change of steering angle ${\dot{\phi }}_{\mathrm{S.}Oll}^v$

of the vehicle 50 depending on the vehicle speed v. At low speeds, a larger steering angle is generally not critical, since there is no safety-critical situation or malfunction of the vehicle 50 tends to be feared. Hence the optimized target value ${\dot{\phi }}_{\mathrm{S.}Oll}^v$

larger in this case. This behavior is shown in the diagram for positive and negative speeds, which correspond to two opposite directions of travel. At higher vehicle speeds 50 however, increased safety risks when steering or maneuvering are to be expected. Hence the optimized target value ${\dot{\phi }}_{\mathrm{S.}Oll}^v$

in this case smaller.

4A shows a schematic representation of a steering sustainability value N and a steering effect value H over time t. Here, the steering sustainability value N is proportional to the rate of change in the steering angle, ie change in the steering angle Δφ per time change Δt. In the case of the time change, an interval between an n-th point in time t _n and an n-1'th point in time t _n-1 is approximately assumed and the change in the steering angle Δφ between these two points in time is determined.
As in 4A Shown by way of example, a change in the rate of change in the steering angle Δφ̇ is also determined for the same time interval, on which the steering effect value H is based. In this way, both values, ie the steering sustainability value N on the one hand and the steering effect value H on the other hand, can be related to one another.

angenommen und die entsprechende Änderung der Lenkwinkeländerungsrate Δφ̇_N bestimmt. Beim Lenkungsnachhaltigkeitswert H wird ein kürzeres Zeitintervall Δt_H zwischen dem Zeitpunkt t_n und einem Zeitpunkt $t_{n-1}^H$

angenommen und die entsprechende Änderung der Lenkwinkeländerungsrate Δφ̇_H bestimmt. 4B shows a schematic representation of a further example in which both values, ie the steering sustainability value N on the one hand and the steering effect value H on the other hand, are set in relation to one another. In this example, both values are determined on the basis of the rate of change in the steering angle φ̇. Here, however, the two values differ in the respective underlying time interval: With the steering sustainability value N, there is a longer time interval Δt _N between a point in time t _n and a point in time $t_{n-1}^N$

is assumed and the corresponding change in the rate of change of steering angle Δφ̇ _{N is} determined. In the case of the steering sustainability value H, there is a shorter time interval Δt _H between the point in time t _n and a point in time $t_{n-1}^H$

is assumed and the corresponding change in the rate of change of steering angle Δφ̇ _{H is} determined.

In the diagram of 4B Another example is shown for both values, whereby the respective reference values are provided with a point index to distinguish them from the above example.

5 FIG. 10 shows a schematic diagram to illustrate an interaction between the steering sustainability value N on the one hand and the steering effect value H on the other hand. The steering impact value H is plotted against the steering sustainability value N. This results in several first areas 34a-d , in which the combinations of the two values N and H (example: the value pair N ₂ and H ₂ ) are permissible, as well as several second ranges 32a-d , in which the combinations of the two values N and H are not permitted (example: the value pair N ₁ and H ₁ ). Between the first areas 34a-d and the second areas 32a-d is always a boundary 30a-d , which indicates the transition, can be seen in the diagram.

Such a diagram can preferably be measured and stored in advance, so that the control device 10 refer to the diagram and compare currently measured value pairs from the steering sustainability value N and the steering effect value H with the diagram. If a currently measured pair of values is in one of the first ranges 34a-d is, there is a permissible steering movement, so that no countermeasure has to be taken. If the currently measured pair of values is in one of the second ranges 32a-d there is an impermissible steering movement, so that a countermeasure must be taken to control the vehicle 50 to move to a safer state.

The diagram out 5 can be expanded from a two-dimensionality of an N- and an H-axis to a three-dimensionality, which additionally includes a v-axis with regard to the vehicle speed v. Such an expanded diagram is shown schematically 6th . For reasons of clarity, in 6th only the three-dimensional allowable areas 36a-d highlighted. For the sake of simplicity, only half is in for positive v-values 6th shown.

Such a diagram can preferably be measured and stored in advance, so that the control device 10 refer to the diagram and compare currently measured value combinations from the steering sustainability value N, the steering effect value H and the vehicle speed v with the diagram. If a currently measured combination of values is in one of the permissible ranges 36a-d is, there is a permissible steering movement, so that no countermeasure has to be taken. Otherwise, there is an impermissible steering movement, so that a countermeasure must be taken to control the vehicle 50 to move to a safer state.
The solution described above for increasing the controllability of steering movements can be used both in non-autonomously driving vehicles and in autonomously driving vehicles, in particular off-road vehicles. In the latter case, the control described above can be combined with a control based on the environment. On the one hand, this increases the response speed of the algorithm on which the environment sensor-based control is based in safety-critical cases or impending malfunctions. On the other hand, incorrect steering commands of the algorithm are limited to safe steering interventions.

List of reference symbols

10

Control device

12

Input interface

14th

Evaluation unit

140

Control loop

142

Comparator

16

Signal unit

18th

Output interface

20th

Vehicle motion sensors

30a-d

Boundaries

32a-d

second areas

34a-d

first areas

36a-d

permitted ranges

50

vehicle

52

Steering device

S1-S5

Procedural steps

Claims (12)

A control method for a vehicle (50) comprising: - obtaining a speed of the vehicle (50); - Establishing a target value for a steering angle of the vehicle (50) based on the determined speed; - Generating a control signal for adapting an actual value of the steering angle to the specified target value; and - Outputting the generated control signal to a steering device (52) of the vehicle (50). A control method for a vehicle (50) comprising: - obtaining a speed of the vehicle (50); - Establishing a target value for a rate of change in the steering angle of the vehicle (50) based on the determined speed; - Generating a control signal for adapting an actual value of the rate of change of steering angle to the specified target value; and - Outputting the generated control signal to a steering device (52) of the vehicle (50). Tax procedure according to Claim 1 or 2 , further comprising monitoring the actual value and generating a control signal for transferring the vehicle (50) to a safe state when the actual value exceeds the target value. Control method according to one of the preceding claims, further comprising determining a steering sustainability value based on a steering angle change rate or its time derivative, and / or determining a steering effect value based on a time derivative of the steering angle change rate. Tax procedure according to Claim 4 , further comprising determining an allowable range for a Value pair comprising the steering sustainability value and the steering impact value. Tax procedure according to Claim 4 or 5 , further comprising determining an allowable range for a combination of values including the steering sustainability value, the steering impact value, and the vehicle speed. A control device (10) for a vehicle (50) comprising: - an input interface (12) for obtaining a speed of the vehicle (50); - An evaluation unit (14) for establishing a setpoint value for a steering angle of the vehicle (50) based on the determined speed; - A signal unit (16) for generating a control signal for adapting an actual value of the steering angle to the specified target value; and - An output interface (18) for outputting the generated control signal to a steering device (52) of the vehicle (50). A control device (10) for a vehicle (50) comprising: - an input interface (12) for obtaining a speed of the vehicle (50); - An evaluation unit (14) for establishing a setpoint value for a rate of change in the steering angle of the vehicle (50) based on the determined speed; - A signal unit (16) for generating a control signal for adapting an actual value of the rate of change of the steering angle to the specified target value; and - An output interface (18) for outputting the generated control signal to a steering device (52) of the vehicle (50). Use of the control device (10) after Claim 7 or 8th in a vehicle (50). Computer program product, comprising instructions which, when the program is executed by a computer, cause the computer to perform the method according to Claim 1 or 2 execute. Computer-readable storage medium on which the computer program product is based Claim 10 is stored. Data carrier signal that the computer program product according to Claim 10 transmits.

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