JP2000225961A - Method for smoothing steering angle transition in active steering system and active steering system thereof - Google Patents

Abstract

(57) [Problem] In an active steering system, when the target value change of the additional steering angle superimposed on the steering wheel angle is drastic, the transition of the steering angle is continuously shifted, and sudden steering wheel rotation is performed. Prevent movement. An open-loop control / closed-loop control unit (37) of an active steering system (37) controls an additional steering angle (δ) from a steering wheel angle sensor (38), an actuator sensor or other sensors (36) and / or a control device in a vehicle.
A signal is obtained that predicts a dramatic transition from the old target value of M to the new target value. Open loop control / closed loop control unit 37
Recognizes, using input signals from the sensors and / or the control device of the vehicle 35, that a dramatic transition of the target value has actually occurred, and smoothes the transition of the target value by a smoothing function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for smoothing a transition of a steering angle in an active steering system and an active steering system, and more particularly, to an additional steering angle to a steering wheel angle set by a driver on a steering wheel. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active steering system for a vehicle to be superimposed, a method of smoothing a transition of a steering angle for smoothing a transition of a drastic change in target value of an additional steering angle, and an active steering system thereof.

[0002]

2. Description of the Related Art A conventional active steering system is known from German Offenlegungsschrift DE-OS 40 33 316 and is shown schematically in FIG. 3 of the accompanying drawings. In such an active steering system, the driver superimposes the additional steering angle δM on the steering wheel angle δL set on the steering wheel 21 with the steering wheel torque M1, thereby superimposing the steering wheel 25a, 25b on the steering angle δL ′. Can be changed independently of the steering wheel angle δL.

[0003] This active steering system is executed by a steering actuator 23 and a superimposed transmission 22. In the superimposed transmission 22, the additional steering angle δM adjusted by the steering actuator 23 is superimposed on the steering wheel angle δL operated by the steering wheel, and the superimposed steering angle δL 'is output to the wheels 25a and 25b. The steering gearbox 24 converts the superimposed steering angle δL ′ into a corresponding movement of the steering tie rod 26.

[0004] Varying the superimposed steering angle, which is adjusted independently of the steering wheel angle, offers advantages in terms of running kinematics, running safety and running comfort. However, when driving such an active steering system, the target value of the additional steering angle may change drastically. This is the case, for example, when a variable reduction ratio is realized in an active steering system. If the ignition has not been started (i.e., in a passive steering system), steering assist is not performed by operating the steering wheel, and the additional steering angle is not adjusted as adjusted by the active steering system.

[0005] As soon as the ignition and the steering system are adjusted by the ignition, an open-loop control / closed-loop control unit (not shown) used in the active steering system sets an additional steering angle dependent on the changed steering wheel position. calculate. However, if you make adjustments immediately,
Do not adjust immediately, as steering wheel movement can be annoying to the driver. For example, it has been proposed to deactivate the active steering system in the steering prohibited area in order to avoid unwanted steering wheel movement.

[0006]

However, as described above, when the active steering system is not ignition-started or when the steering is performed in a steering prohibited area where the active steering system is released, the traveling state changes. Since the vehicle movements change in the course, for example, steering interventions to stabilize the vehicle need to take other values.

That is, when the active steering system has not been started, or while the driver holds the steering wheel in the steering prohibited area, the operation of the active steering system is not executed. When steering in such a way, new steering interventions must be adjusted immediately to stabilize the vehicle. At this time, the active steering system is started again,
The transition from a steering intervention before the steering system is released to a steering intervention that has been changed due to a change in the driving situation must not be executed rapidly or drastically. In the past, since the change in the target value of the additional steering angle was drastic, sudden steering wheel rotation occurred, giving the driver discomfort, and there was also a problem in the safety of running the vehicle. Was.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to continuously shift the steering angle when the target value change of the additional steering angle superimposed on the steering wheel angle is drastic, thereby preventing sudden steering wheel rotation. It is an object of the present invention to provide a new and improved active steering system capable of performing the steering angle transition smoothing method and the active steering system.

[0009]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a predetermined vehicle condition, a steering execution condition or a surrounding state is determined with respect to a steering wheel angle set by a driver on a steering wheel. In an active steering system for a vehicle that superimposes an additional steering angle according to a situation, a method of smoothing a transition of the steering angle when a target value change of the additional steering angle is drastic, wherein the additional steering angle is changed. A first recognizing step of recognizing whether or not there is a situation where a leap occurs in the change of the target value. 2) and a processing step of continuously shifting the additional steering angle from the old target value to the new target value based on a predetermined smoothing function or a smoothing function that can be selected according to the situation. Smoothing method of the steering angle transition, wherein is provided.

According to the invention described in this item, for example, when the ignition of the vehicle is released, the steering system is operated, or when the steering wheel angle is in the steering prohibited region, the additional steering angle always jumps to the target value change. It recognizes whether or not there is a situation in which occurs. If such a situation actually resulted in a dramatic shift in the target value of the additional steering angle, a continuous transition from the old target value of the additional steering angle to the new target value using a smoothing function or a software algorithm. Therefore, safety can be significantly improved in the active steering system. Further, since the target value of the additional steering angle continuously shifts, sudden turning of the steering wheel is avoided, and the driver does not feel uncomfortable, so that the traveling comfort of the vehicle is increased.

According to a second aspect of the present invention, in the processing step, the transition of the additional steering angle from the old target value to the new target value is smoothed according to a ramp function. The transition of the angle target value can be made continuous. Similarly, in the processing step, the transition of the additional steering angle from the old target value to the new target value may be smoothed according to a sine function. Similarly, in the processing step, the transition of the additional steering angle from the old target value to the new target value can be smoothed according to an arc function. Further, similarly, in the processing step, the transition of the additional steering angle from the old target value to the new target value can be smoothed according to a hyperbolic function.

According to the present invention, a plurality of smoothing functions for executing a continuous transition in the processing step indicate a predetermined driving situation and / or a driver operation of a steering wheel. Stored in a table in advance in accordance with the parameters, and in the processing step, in accordance with the parameters formed in the first and / or the second recognition step,
If the smoothing function is selected, if a drastic change in the target value is recognized, the smoothing function adjusted according to the predetermined driving situation and / or the driver's operation on the steering wheel is selected from the table. The time required for the calculation of can be saved, and a quick response can be made.

According to a seventh aspect of the present invention, in the processing step, the smoothing function is calculated according to the parameters formed in the first and / or the second recognition step. , A first and / or a second recognition step, a suitable smoothing function can be obtained depending on the parameters formed.

According to the present invention, in the first and / or the second recognition step, the steering system is operated from ignition start, and the steering wheel angle is set in the steering prohibited area. If it is configured so as to recognize that there is a jump in the target value of the additional steering angle when the steering system is operated from the ignition start, or when the driver returns from the steering prohibited area, a new steering operation is performed. Even if a jump occurs in the intervention, the transition of the target value of the additional steering angle can be made continuous by the smoothing function.

In order to solve the above-mentioned problem, according to the ninth aspect of the present invention, the steering wheel angle set by the driver via the steering wheel, the set steering wheel angle, the vehicle condition or the surroundings. An active steering system having an open-loop control / closed-loop control unit in which a superimposed transmission superimposes an additional steering angle according to a situation-dependent parameter, said open-loop control / closed-loop control unit comprising a steering wheel connected to a steering wheel shaft. An input signal for predicting a drastic transition from the old target value to the new target value of the additional steering angle, which is output from an angle sensor, an actuator sensor installed on a steering actuator or another sensor in the vehicle and / or a control device, is provided. And the input signal Recognizing whether or not a dramatic shift in the target value of the steering angle actually occurred, and recognizing that the dramatic shift in the target value actually occurred, based on a predetermined smoothing function or situation. An active steering system is provided that performs a continuous transition of the additional steering angle from the old target value to the new target value according to a selectable smoothing function.

According to the present invention, when the ignition of the vehicle is released, the steering system is operated, or when the steering wheel angle is in the steering prohibited area, the additional steering angle always jumps to the target value change. It is recognized whether or not there is a situation in which occurs. If such a situation actually resulted in a dramatic shift in the target value of the additional steering angle, a continuous transition from the old target value of the additional steering angle to the new target value using a smoothing function or a software algorithm. Therefore, safety can be significantly improved in the active steering system. Further, since the target value of the additional steering angle continuously shifts, sudden turning of the steering wheel is avoided, and the driver does not feel uncomfortable, so that the traveling comfort of the vehicle is increased.

Also, as in the invention according to claim 10,
The open-loop control / closed-loop control unit stores a plurality of smoothing functions on the basis of a continuous transition in the form of a table in accordance with corresponding parameters calculated from predetermined driving situations and / or driver actions and / or surrounding situations. It has a memory for storing in advance, reads out the previously stored smoothing function from the memory, and smoothes the transition from the old target value to the new target value by a table control method. Necessary time can be saved and quick responses can be made.

[0018]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
In the following description and the accompanying drawings, components having the same functions and configurations will be denoted by the same reference numerals, and redundant description will be omitted.

(First Embodiment) Hereinafter, a first embodiment will be described with reference to FIG. Figure 1
FIG. 2 is a functional block circuit diagram of the active steering system according to the embodiment.

As shown in FIG. 1, the steering wheel angle δL which is set by the steering wheel 31 of the vehicle 35 and acts on the input side of the superimposed transmission 32 via a steering wheel shaft (not shown).
Is detected by a steering wheel angle sensor 38 connected to a steering wheel shaft and supplied to an input side of an open loop control / closed loop control unit 37.

The other sensors 36 installed in the vehicle are used to detect the steering angle δV of the front wheels, the running speed or other actual values of the vehicle situation and the surrounding situation. It is supplied to the input side of the control unit 37. The open-loop control / close control unit 37 generates an output voltage U according to the supplied input amount, and the output voltage is supplied to the steering actuator 33. The additional steering angle δM is output to the output shaft of the steering actuator and supplied to another input of the superimposed transmission 32.

Open loop control / closed loop control unit 37
Is configured to detect in the present embodiment whether or not there is a situation in which a leap can occur in the target value of the additional steering angle δM based on the supplied input signal.

Open loop control / closed loop control unit 37
However, if it is detected that a significant change in the target value of the additional steering angle δM has actually occurred, a smoothing process for continuously shifting the target value from the previous target value to the new target value is performed. Execute. Therefore, in the open loop control / closed loop control unit 37, a predetermined smoothing function (for example, a ramp function, a sine function, a part of an arc or a parabola) is set or calculated. Similarly, the open-loop control / closed-loop control unit 37 determines that a plurality of smoothing functions, each of which is the basis of a continuous transition, have corresponding parameters calculated based on predetermined driving conditions and / or driver behavior or surrounding conditions. May be provided with a memory for storing in advance as a table.

At this time, the open-loop control / closed-loop control unit 37 reads out the smoothing function from each of the pre-stored memories 39, and uses the table control method to jump from the old target value to the new target value. The transition can be smoothed.

Next, the smoothing function according to this embodiment will be described with reference to FIG. FIG. 2 shows the additional steering angle δM
FIG. 7 is a graph comparing a leaping function A indicating a dramatic change in the target value of FIG. 1 with smoothing functions (B1, B2). Here, two smoothing functions of, for example, a ramp function B1 (shown by a broken line) and a sine-shaped curve B2 (shown by an alternate long and short dash line) are shown as the smoothing functions.

Of course, the open-loop control / closed-loop control unit 37 controls each smoothing function (for example, functions B1 and B2).
Can be calculated according to a predetermined parameter derived from the input signal instead of storing in a table format according to a predetermined parameter calculated in advance. At this time, when a remarkable change in the target value is recognized, priority is given to the table control, so that the time required for calculating the function can be saved and the response can be promptly made.

Although the preferred embodiment according to the present invention has been described above, the present invention is not limited to such a configuration.
Those skilled in the art can envisage various modified examples and modified examples within the scope of the technical idea described in the claims, and those modified examples and modified examples are also included in the technical scope of the present invention. It is understood to be included in.

For example, in the above-described embodiment, the smoothing function for making the dramatic change in the target value continuous has been described with specific examples, but a smoothing function other than the above-described smoothing function may be appropriately adopted. Can be.

[0029]

For example, when the vehicle is de-ignited, the steering system is operated, or the steering wheel angle is in the steering prohibited area, a jump in the change in the target value of the additional steering angle always occurs. Recognize whether it exists. If such a situation actually resulted in a dramatic shift in the target value of the additional steering angle, a continuous transition from the old target value of the additional steering angle to the new target value using a smoothing function or a software algorithm. Therefore, safety can be significantly improved in the active steering system. Further, since the target value of the additional steering angle continuously shifts, sudden turning of the steering wheel is avoided, and the driver does not feel uncomfortable, so that the traveling comfort of the vehicle is increased.

[Brief description of the drawings]

FIG. 1 is a functional block circuit diagram of an active steering system according to an embodiment.

FIG. 2 is a graph showing a comparison between a jump function A indicating a drastic change in a target value of an additional steering angle δM and smoothing functions (B1, B2).

FIG. 3 is a functional block circuit diagram of a conventional active steering system.

[Explanation of symbols]

 31 steering wheel 33 steering actuator 35 vehicle 37 open loop control / closed loop control unit 38 sensor

Continued on the front page (72) Inventor Wolfgang Kramer Germany 70191 Stuttgart, Birkenwaldstrasse 133

Claims (10)

[Claims] In an active steering system for a vehicle, an additional steering angle according to a predetermined vehicle situation, a steering execution situation or a surrounding situation is superimposed on a steering wheel angle set by a driver on a steering wheel. A method for smoothing the transition of the steering angle when the change in the target value of the above is drastic, and recognizing whether or not there is a situation in which the change in the target value of the additional steering angle occurs. A first recognition step, a second recognition step of recognizing whether or not the remarkable shift of the additional steering angle to the target value actually occurred, and a predetermined smoothing function or a smoothing function selectable depending on the situation. A step of continuously shifting the additional steering angle from the old target value to the new target value based on the calculated steering angle. 2. The steering angle shift according to claim 1, wherein in the processing step, a shift of the additional steering angle from the old target value to the new target value is smoothed according to a ramp function. Smoothing method. 3. The steering angle shift according to claim 1, wherein, in the processing step, a shift of the additional steering angle from the old target value to the new target value is smoothed in accordance with a sine function. Smoothing method. 4. The steering angle shift according to claim 1, wherein in the processing step, a shift of the additional steering angle from the old target value to the new target value is smoothed in accordance with an arc function. Smoothing method. 5. The steering angle transition according to claim 1, wherein the transition of the additional steering angle from the old target value to the new target value is smoothed in accordance with a hyperbolic function. Smoothing method. 6. A plurality of smoothing functions for executing a continuous transition in the processing step are stored in a table in advance in accordance with a predetermined driving situation and / or parameters indicating a driver operation of a steering wheel. 6. The processing step, wherein the smoothing function is selected according to the parameters formed in the first and / or second recognition step. The method for smoothing steering angle transition according to any one of the preceding claims. 7. The method according to claim 1, wherein in the processing step, the first and / or
2. The method according to claim 1, wherein the smoothing function is calculated according to a parameter formed in the second recognition step. 3. 8. The method according to claim 1, wherein in the first and / or second recognition step, it is recognized that a steering system is operated from ignition start and that a steering wheel angle is in a steering prohibited area. Terms 1, 2, 3,
The method of smoothing steering angle transition according to any one of items 4, 5, 6, and 7. 9. An open transmission for superimposing an additional steering angle on a steering wheel angle adjusted by a driver via a steering wheel in accordance with the set steering wheel angle, a parameter corresponding to a vehicle situation or a surrounding situation. An active steering system having a loop control / closed loop control unit, wherein the open loop control / closed loop control unit is a steering wheel angle sensor connected to a steering wheel shaft, an actuator sensor installed on a steering actuator, or another in-vehicle sensor. And / or obtaining an input signal output from the control device for predicting a dramatic transition from the old target value to the new target value of the additional steering angle, and using the input signal, a dramatic transition of the additional steering angle to the target value. Recognizes whether the event actually occurred If it is recognized that the dramatic transition of the target value has actually occurred, the new target value of the additional steering angle is converted from the old target value of the additional steering angle according to a predetermined smoothing function or a smoothing function that can be selected based on the situation. Active steering system characterized by performing a continuous transition to a steering wheel. 10. The open-loop control / closed-loop control unit comprises a plurality of smoothing functions on which a continuous transition is based, according to corresponding parameters calculated from predetermined driving situations and / or driver actions and / or surroundings. Each having a memory for storing in advance in a table format, reading the previously stored smoothing function from the memory, and smoothing the transition from the old target value to the new target value by a table control method. The active steering system according to claim 9, wherein: