DE102020133651A1 - Method for correcting a yaw rate - Google Patents

Abstract

The invention relates to a method for correcting a yaw rate in a - in particular autonomously operable - vehicle, a current actual yaw rate (Aist) being determined and at least one steering angle (α) when the actual yaw rate (Aist) deviates from a normal Yaw rate (Aα, v) determined target yaw rate (A (α, v)) is corrected by means of a steering controller, with at least one normal yaw rate (Aα, v) of the vehicle based on at least one defined vehicle speed (v), a steering angle input ( α) and a defined vehicle weight is determined and a basic adjustment of the controller parameters of the steering controller is carried out. To relieve the steering controller, it is provided that at least one for a deviation of the actual yaw rate (Aist) from the target yaw rate (A (α, v)) specific correction value (Kα, v) for the steering angle input (α) is assigned to a precontrol value (W) for the steering controller and the manipulated variable of the steering controller with the precontrol value (W) b is billed.

Description

The invention relates to a method for correcting a yaw rate in a - in particular autonomously operable - vehicle, a current actual yaw rate being determined and at least one steering angle when the actual yaw rate deviates from a target yaw rate determined from a normal yaw rate by means of a steering controller is corrected, wherein at least one normal yaw rate of the vehicle is determined on the basis of a vehicle speed, a steering angle input and a vehicle weight and a basic adjustment of the controller parameters of the steering controller is carried out.

The yaw rate describes the angular speed of the rotation of a vehicle around the vertical axis.

From the DE 10 2008 011 017 A a vehicle control device for controlling the vehicle behavior is known which has a steering angle control device for correcting a steering angle on the basis of the allowable driving forces of the individual drive wheels. On the basis of the permissible drive forces of the individual wheels, the steering angle control device calculates a yaw moment which occurs due to a difference in the drive forces between a left and a right wheel.

The WO 2016/121546 A1 discloses a vehicle control device which has calculating means for calculating a normal yaw rate based on the vehicle speed and a steering angle. Furthermore, the vehicle control device has a calculation device for calculating a target yaw moment based on a deviation between a normal yaw rate and a current yaw rate. A yaw moment regulating device is used to provide a target yaw moment for each wheel by means of drive or braking force commands. A similar vehicle control device is known from US Pat US 9,296,418 B2 known.

If the vehicle configuration on which the basic tuning of the control device is based changes or if the vehicle weight changes compared to the vehicle weight on which the basic tuning is based, then control interventions are constantly required in the known vehicle control device, which burdens the controller and adversely affects the control speed and the service life of the steering controller affects.

The object of the invention is to reduce the load on the steering controller.

According to the invention, this is achieved in that at least one correction value for the steering angle input determined when the actual yaw rate deviates from the target yaw rate is assigned a precontrol value for the steering controller and the control value of the steering controller is acted upon with the precontrol value.

A precontrol value of a precontrol of a controller is a value with which a manipulated variable of the controller is applied, the precontrol value being independent of the states of the controlled system and the measurements resulting therefrom.

Because the correction of the steering angle input is carried out as a precontrol, the steering controller is significantly relieved. The manipulated variable of the steering controller can be added or multiplied by the pre-control value.

The correction value is advantageously determined for different driving speeds and / or steering angles and assigned pre-control values, the correction value being / are preferably stored in a correction map and / or the pre-control value in a pre-control map as a function of the driving speed and / or the steering angle input.

One embodiment variant of the invention provides that the pilot control value is determined and / or readjusted in a self-learning process.

Corrections by means of pre-control values are particularly suitable for all deviations that can be traced back to static causes, for example changes in the equipment of the vehicle and / or weight. Therefore, in one embodiment of the invention, before the correction value is assigned to the precontrol value - preferably before the correction value is stored in a correction map - it is checked whether the deviation is present the actual yaw rate persists from the target yaw rate over a defined period of time and / or occurs repeatedly at the corresponding speed and the corresponding steering angle input. The correction value is only assigned to the precontrol value if the deviation of the actual yaw rate from the target yaw rate persists over a defined period of time and / or occurs repeatedly at the corresponding speed and the corresponding steering angle input.

The invention is explained in more detail below on the basis of an exemplary embodiment, the method according to the invention being shown schematically in the figure.

During the development process of the vehicle, a basic adjustment of the controller parameters of the steering controller is carried out. _{A measurement of the resulting normal yaw rate A α, v} in rad / sec over the vehicle speed v and the steering angle input α is carried out for a vehicle that is not locked - for example a vehicle in the delivery state with series tires - and this resulting normal yaw rate A _α, v stored as the target yaw rate A (α, v) as a function of the steering angle input α and the vehicle speed v:

When implemented in real driving mode, a vehicle drives, for example, at a speed v of 50 km / h and the steering angle input α is 30 °. However, only an actual yaw rate A _{ist of} the vehicle is measured, which is 0.9 * A _30.50 . A short-term deviation of the actual yaw rate A _is from the target yaw rate target yaw rate A (α, v) can be applied to short-term effects - such as wind or vehicle inclination - be caused, which can be dynamically compensated for by the steering controller. In the case of a long-term deviation of the actual yaw rate A _ist from the target yaw rate, target yaw rate A (α, v), differences in equipment, for example different tire brands, tire types, tire sizes, rim sizes and / or a change in the vehicle weight may be the cause. Such influences would conventionally have to be constantly compensated for by the steering controller, which puts an additional strain on it.

• Wenn ausgeschlossen werden kann, dass die Abweichung auf eine kurzzeitige dynamische Einflussgröße - beispielsweise auf Windeinfluss oder Fahrbahnneigung - zurückzuführen ist, so wird in einem Korrekturkennfeld zum Beispiel an der Stelle v=50 km/h und α = 30° ein erhöhender Korrekturwert K_α,v = K_30,50 eingetragen:

Instead, the invention takes a different approach:

• If it can be ruled out that the deviation is due to a short-term dynamic influencing variable - for example, the influence of wind or road inclination - then an increasing correction value K _{α, for example at v = 50 km / h and α = 30 °, is shown in a correction map. v} = K _30.50 entered:

This correction value K _{α, v} = K _30.50 is assigned to a precontrol value W for the manipulated variable of the steering controller the next time the vehicle is operated again at a speed v of 50 km / h and a steering angle input α of 30 ° this precontrol value W added up either additively or multiplicatively to the steering angle input α. This means that the control system of the steering controller outputs more than 30 ° as the manipulated variable output for the steering angle input α and thus _{“learns” itself to the target yaw rate A 30.50} at this point. In the case of an overshoot or a too high actual yaw rate A _is learning the control system accordingly in the other direction.

In the development process, the vehicle yaw rate is measured and this target value A (α, v) for the yaw rate is stored as a function of the steering angle input α and the vehicle speed v. In vehicle operation, the vehicle _{yaw rate is} measured and the yaw rate is stored as actual value A in% of setpoint A (α, v).

Shows the comparison between the reference value A (α, v) and the actual value A _is the yaw rate deviation, for example, of example, 10% of the target value A (α, v), or about 0.9 · A (α, v), it must the steering angle input α can be increased in order to reach the target value A (α, v).

In the first approximation, the steering angle input α is increased by an applicable value to the corrected steering angle input α _corr . The corrected steering angle input α _corr is output to the steering system in order to achieve the target yaw rate A (α, v) for the given vehicle speed.

If the next steering operation, the actual value A _is lying for the yaw rate is below the target value A (α, v), the steering angle input is α raised further. If the next steering operation, the actual value A _is lying for the yaw rate to the target value A (α, v), the steering angle input is α reduced.

In the figure, the essential steps of the method in driving mode are shown schematically. In step 1 it is checked whether the actual value A _ist the yaw rate deviates from the corresponding nominal value A (a, v). If no discrepancy can be found, no action is necessary (reference number 2). _{If the query A ist} > A (α, v) indicated by reference number 3 shows _{that the actual value A ist} the yaw rate is greater than the corresponding setpoint A (α, v), a corresponding correction value K _{α, v} <1 for the steering angle input α entered in the correction field. If the actual value A _ist the yaw rate is less than the corresponding nominal value A (α, v), a corresponding correction value K _{α, v} > 1 for the steering angle input α is entered in the correction field.

• • Der Lenkwinkelinput kann manuell durch den Fahrer oder automatisiert zum Beispiel durch ein autonomes System erfolgen.
• • Das Stellglied kann eine hydraulische, elektrische, elektro-hydraulische, pneumatische oder jede andere Art einer kontrollierbaren Kontrolle zur Umsetzung von Lenkwinkel auf Anstellwinkel der gelenkten Räder sein.
• • Die positive Korrektur (Anhebung der Gierrate) oder negative Korrektur (Reduktion der Gierrate) durch das Verfahren wird von dem Stellglied zusätzlich zum Grundausgabewert additiv oder multiplikativ umgesetzt.

The method according to the invention can always be used when an actuator exists between the steering angle input and the adjusting angle of the articulated wheels.

• • The steering angle input can be done manually by the driver or automated, for example by an autonomous system.
• • The actuator can be a hydraulic, electrical, electro-hydraulic, pneumatic or any other type of controllable control for converting the steering angle to the angle of attack of the steered wheels.
• • The positive correction (increase of the yaw rate) or negative correction (reduction of the yaw rate) by the method is implemented by the actuator in addition to the basic output value additively or multiplicatively.

Deviations from the target yaw rate to the actual yaw rate can be corrected by means of the method according to the invention.

• • Unterschiedlichen Räder-/Reifenkombinationen (Breite, Durchmesser, Winterreifen/Sommerreifen);
• • Reifenverschleiß;
• • allgemeiner Verschleiß (zum Beispiel erhöhtes Lenkungsspiel, Spiel in den Traggelenken, etc.);
• • unterschiedliche Ausstattungsvarianten können ein abweichendes Fahrzeuggesamtgewicht von dem des Basisfahrzeuges und somit eine geänderte Gierrate verursachen;
• • unterschiedliche Beladungszustände;

Such deviations can be caused by:

• • Different wheel / tire combinations (width, diameter, winter tires / summer tires);
• • tire wear;
• • general wear and tear (for example increased steering play, play in the ball joints, etc.);
• • Different equipment variants can cause a different gross vehicle weight from that of the base vehicle and thus a different yaw rate;
• • different loading conditions;

With the method according to the invention, the control effort and the wear and tear of the steering controller can be significantly reduced.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102008011017 A [0003]
• WO 2016/121546 A1 [0004]
• US 9296418 B2 [0004]

Claims (5)

A method of correcting a yaw rate in a - in particular autonomously operated - vehicle, a current actual yaw rate (A _is) is determined, and at least one steering angle (α) on deviation of the actual yaw rate (A _is) from one of a normal yaw rate (A _{α, v} ) determined target yaw rate (A (α, v)) is corrected by means of a steering controller, with at least one normal yaw rate (A _{α, v} ) of the vehicle based on at least one defined vehicle speed (v), a steering angle input ( α) and a defined weight of the vehicle is determined and a basic set of controller parameters is carried out of the steering controller, characterized in that at least one of a deviation of the actual yaw rate (a _is) from the target yaw rate (a (α, v) of certain) correction value ( K _{α, v} ) for the steering angle input (α) is assigned to a precontrol value (W) for the steering controller and the control value (W) is applied to the manipulated variable of the steering controller. Procedure according to Claim 1 , characterized in that the correction value (K _{α, v} ) is / are stored in a correction map and / or the pilot control value (W) in a pilot control map as a function of the driving speed (v) and / or the steering angle input (α). Procedure according to Claim 1 or 2 , characterized in that the pilot control value (W) is determined and / or readjusted in a self-learning process. Method according to one of the Claims 1 to 3 , characterized in that the manipulated variable of the steering controller is acted upon by the pilot control value (W) in an additive or multiplicative manner. Method according to one of the Claims 1 to 4th , characterized in that before the assignment of the correction value to the precontrol value (W) - preferably before the correction value is stored in a correction map - it is checked whether the deviation of the actual yaw rate (A _ist ) from the target yaw rate (A (α , v)) lasts for a defined period of time and / or occurs repeatedly at the corresponding speed (v) and the corresponding steering angle input (α), and an assignment of the correction value to the pre-control value (W) is only carried out if the deviation from the actual -Gierrate (a _is) desired yaw rate (a (α, v)) of the holding over a defined period of time and / or repeatedly occurs at the corresponding speed (v) and the corresponding steering angle input (α).

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