DE102011086897A1 - Tracking assistance method for motor vehicle, involves continuously correcting slight lateral deviation of vehicle from target trajectory by automatic correction of steering movements by adjusting calculated target wheel steering angle - Google Patents

Abstract

The additional hand moments applied to a steering handle of motor vehicle (20) towards the center (23) of a detected driving lane (21) are assisted to driver of the motor vehicle as steering recommendations for the tracking. The slight lateral deviation of the motor vehicle from the target trajectory (26) is continuously corrected by automatic correction of steering movements, by adjusting calculated target wheel steering angle so that motor vehicle maintains the target trajectory when the driver drives along a determined target trajectory. Independent claims are included for the following: (1) electronic rule and control device; and (2) electronic power steering system.

Description

The invention relates to a tracking assistance method for a motor vehicle having an electronic power steering system. The invention also relates to an electronic control unit of a motor vehicle for carrying out the tracking assistance method and to an electronic power steering system of a motor vehicle.

Lane assistance systems are known from the prior art, in which the driver of a motor vehicle is continuously supported by an additional torque on the steering wheel when tracking depending on its position and movement in the currently traveled lane. This additional torque is generally used to give the driver a haptic feedback of the track course and its position relative to the lane boundary. In order to obtain the typical vehicle steering feel, in the area around the lane center, the so-called free space usually no additional torque is superimposed. The driver should not be disturbed in the long term by the constant readjustment of the steering wheel. If the vehicle position leaves this clearance, the system is reactivated and there is a noticeable moment in the direction of the lane center. The controller parameters, i. H. the strength of the controller or the Regelrintensität successively increases as the vehicle moves away from the lane center to prevent dangerous approaching to the edge of the lane. The required lane data are provided, for example, by an environment sensor system, in particular in the form of radar or camera systems. With such sensor systems for detecting the vehicle environment, the position and movement of the motor vehicle relative to its surroundings can be detected by measurement. In addition, camera systems are available which recognize the course of the road in front of the motor vehicle using existing road markings and output the position of the motor vehicle relative to the traffic lane. Taking into account such data, certain driving situations such as changing the lane or leaving the lane or slow approach to a neighboring lane can be detected. Systems that actively support the driver through directed steering torque or torque recommendations while holding the vehicle and the lane are also referred to as LKS (Lane Keeping Support) systems.

The concept of the LKS systems leads to a high level of driver acceptance, as it is not restricted by the clearance in the middle of the lane during the steering process. On the other hand, this lack of steering recommendation can lead to slight oscillations around the track center, if the driver does not steer properly. This causes the vehicle often exceeds the limits of the free space area and the driver feels a steering recommendation on the steering wheel.

In the DE 10 2004 039 142 A1 a method for assisting the driver of a motor vehicle in the tracking is specified in which at least one associated with the distance of the vehicle to the lane boundary tracking parameter for the motor vehicle is determined and depending on the tracking size a driver independent steering wheel torque is exerted on the steering wheel.

The DE 10 2007 043 912 A1 relates to a method for controlling a driver assistance system of a vehicle with LKS function, in which the activation of the LKS function can cause a lateral oscillating movement of the vehicle. In the method, the course of the vehicle is monitored to see if a lateral pendulum motion occurs. When detecting a pendulum movement, the driver assistance system is controlled such that the pendulum motion of the vehicle is completely prevented or at least largely reduced.

From the DE 197 51 125 A1 is a steering system with overlay means known. There, the movement (additional angle or motor angle) of an actuator, ie an electric motor superimposed by means of a superposition gear (for example, a planetary gear) with the steering wheel angle. With the help of the superimposition means, it is possible to superimpose a steering wheel angle predefined by the steering handle to increase driving stability or comfort with an additional angle, so that a variable transmission ratio between steering wheel angle and mean steering angle of the steerable wheels of the motor vehicle is dependent on the driving dynamics or comfort. As a result, it is safety z. B. possible, a motor vehicle, which threatens to break out, due to a corresponding correction of the steering angle back into a stable driving situation. The overlay means may support other vehicle dynamics systems (eg, an electronic stability program (ESP) or an anti-lock braking system (ABS)). In terms of comfort, it is also possible to superimpose a speed-dependent additional angle on a steering wheel angle, for example. As a result, a relatively small transmission ratio can be set at low vehicle speeds, ie, a relatively small rotation of the steering handle leads to a relatively large steering angle of the wheels. At high vehicle speeds, however, a relatively large gear ratio can be adjusted so that the driving stability of the motor vehicle increases.

From the DE 100 13 711 A1 is a steering system is known, including a servo drive for torque assistance (power steering) having. The degree of torque assistance is dependent on the vehicle speed in the described steering system. While the torque assist is greater at slower vehicle speeds (eg, to operate the steering wheel with little effort when maneuvering the vehicle), torque assist is reduced at higher speeds (eg, to increase driving stability on a highway ride). The servo drive can work electrically or hydraulically. In the electronic power steering system according to the invention, the torque assistance can be electrically varied. That in the DE 100 13 711 A1 described steering system has in addition to the servo drive and superimposition means which generate an additional angle and superimpose the steering wheel angle predetermined by the steering handle with this additional angle.

The present invention has for its object to further improve a tracking assistance method of the type mentioned above, in particular to effectively counteract a pendulum motion of the motor vehicle in the area around the lane center and to further increase the acceptance by the driver of the motor vehicle.

This object is achieved by a tracking assistance method for a motor vehicle with an electronic power steering system, which supports the driver of the motor vehicle by one or more applied to a steering handle of the motor vehicle auxiliary hand moments in the direction of the center of a detected traffic lane as steering recommendations in tracking, and which the Driver of the motor vehicle additionally supported while driving along a determined target trajectory such that minor lateral deviations of the motor vehicle from the target trajectory are continuously corrected by automatic correction steering movements, which adjust a calculated target wheel steering angle, which holds the motor vehicle at least approximately on the target trajectory.

Advantageously, the driver is supported by the tracking assistance method according to the invention with the aid of further measures when using an LCS system. This can be z. B. in the area of the above-mentioned space, so that a pendulum of the vehicle is counteracted about the track center. The concept presented may give the driver the feeling of improved lane behavior and reduce the number of torque interventions by the LKS system. When activated torque control of the track is carried out according to the invention at the same time an additional correction by an angle control of the vehicle. This angle control aims at correcting slight disturbances of the path deviation and keeping the vehicle in the area of the center of the road. In contrast to the steering recommendation of a LKS system by means of additional manual torques, in which the driver is within the control loop, the driver is arranged outside the control loop in the continuous automatic correction steering movements according to the invention. The driver is thus supported in the control task. The corrective interventions are not noticeable to the driver. The improved quality of the tracking system significantly increases safety. The slight lateral deviations of the motor vehicle from the desired trajectory can be caused, for example, by road bumps, a road bank, side winds and / or joints or ruts of the roadway.

The additional manual torques in the direction of the center of the detected driving lane can be adjusted by means of a servo drive of the electronic power steering system for torque assistance. Such an electric servo drive, for example an electric power steering (EPS) system, can assist the driver in the control process of the motor vehicle.

The automatic corrective steering movements can be performed by superimposing means of the electronic power steering system, which have a Zusatzwinkelsteller, wherein the superimposing means for correcting produce a corresponding additional angle through the Zusatzwinkelsteller and superimpose the steering wheel angle of the driver with the additional angle. The solution according to the invention is very advantageous for vehicles with a so-called active steering system (AFS / Active Front Steering), since a control of additional angles on the wheel is made possible without a reaction on the steering wheel.

In the method according to the invention, therefore, a combined or networked superposition of steering angles (by AFS) and steering moments (by EPS) is achieved. The guidance assistance method according to the invention advantageously combines an LKS system with an AFS angle control and offers continuous assistance to the driver, in particular on highway-like lanes. For this purpose, the method determines the desired track position of the driver and keeps the vehicle by an exact control over the active steering in this ideal lane. It thus relieves the driver of having to carry out constant steering corrections as soon as occurring disturbances by the vehicle or by the environment cause deviations from this ideal track. Of great importance for the functional execution of the function are in addition to the appropriate design of the additional angle and the components for monitoring and control of the overall system.

Alternatively, of course, a Steer by wire steering system can be used, which is also able to produce both functionalities.

The additional manual torques in the direction of the center of the lane can essentially be applied in a first defined area of the detected traveled lane. In addition, the automatic correction steering movements can essentially be carried out in a second defined region of the lane around the target trajectory.

By these measures, different operating points of the actuators can be adjusted. It can thereby be achieved that the angle controller is designed so that the control intensity, which corresponds to the height of the control parameters in the free space area is as high as possible and when leaving this area, the control parameters are successively reduced, so that too high lane deviation primarily the torque recommendation of the LKS -Systems the driver leads towards the middle of the lane. The first and second defined lateral areas may also overlap.

The second defined area of the detected traveled lane may be a free space in which no additional manual torques are generated in the direction of the center of the lane. The driver can therefore be supported in readjusting the vehicle, in particular within the free space area, in which no interventions by the LKS system take place.

The controller parameters for the regulation of the automatic corrective steering movements and / or the additional manual torques in the direction of the center of the traffic lane may be continuously adaptable, in particular as a function of the current lateral deviation of the motor vehicle from the desired trajectory and / or the current vehicle speed. Accordingly, the controller parameters of the angle controller or of the torque controller may be designed adaptively as a function of the instantaneous track deviation and the vehicle speed.

The control intensity of the additional manual torques may be low in the second defined area of the detected traveled lane and may increase in the direction of the first defined area up to the edge of the lane. Furthermore, the control intensity for the automatic correction steering movements in the second defined area of the detected traveled lane can be high and decrease successively with increasing lateral deviation of the motor vehicle from the desired trajectory in the direction of the first defined area of the detected traveled lane. The first defined area of the detected traffic lane may extend on both sides about 20 cm to about 30 cm from the lane edge in the direction of the center of the detected traffic lane. The second defined area of the detected traffic lane can be z. 30 cm to approx. 40 cm around the center of the covered traffic lane.

This results in a different distribution of the operating points of both actuators. The angle control (AFS) takes place mainly in a defined area around the track center (about 30 cm-about 40 cm), preferably in the free space area of the torque controller (EPS), in which no additional manual torques are generated in the direction of the center of the lane. The torque control takes place mainly in a defined range from the middle of the lane (right and left from approx. 20 cm - 30 cm up to the edge of the lane) and rising towards the edge of the lane. In addition, the torque recommendation of the EPS system plays a decisive role when cornering. Here, it executes a feedforward control of the required steering angle so that the curve can be passed comfortably and safely. The control intensity or the height of the control parameters of the angle control can be high in the free space area and can be successively reduced when leaving.

As primary controller parameters for the automatic correction steering movements, a lateral track deviation, determined by signals from sensor devices of the motor vehicle for detecting the vehicle environment, relative to the target trajectory, a lateral track speed, a relative yaw angle and / or a radius of the detected traveled lane can be used. In addition, a yaw rate, a lateral acceleration and / or a slip angle can be used as secondary control parameters for the automatic correction steering movements. The primary control parameters are thus the lateral track deviation and / or the lateral track speed and / or the relative yaw angle and the radius of the lane, with the yaw rate and / or the lateral acceleration and / or the slip angle being considered as secondary control parameters. By considering the relative yaw angle as a primary controller parameter, oscillations can be effectively prevented. Thus, a compromise between accuracy and dynamics is achieved.

It is advantageous if a driver's preferred, in particular short-term and / or long-term lateral offset detected by the center of the detected traveled lane, evaluated in its time course and continuously taken into account in the determination of the desired trajectory. Normal drivers drive the vehicle on one for them individually determined ideal track position (lane offset), which in most cases does not correspond to the objectively measured road center, but has a slight offset in the direction of the left or right lane edge. In an advantageous embodiment of the invention may be provided in the trajectory planning to determine by an evaluation of the track position and the observation of driver behavior, the lane offset and to provide the control system. This evaluation should not only be done once, but can be carried out continuously during the entire journey. Many normal drivers change their desired set lane depending on the driving situation, for example when a wider vehicle on the neighboring lane is overtaken.

The continuous automatic correction steering movements can preferably be adjusted at least approximately straight ahead driving the motor vehicle or when driving on slightly curved sections.

For determining the desired trajectory, sensor devices of the motor vehicle for detecting the vehicle surroundings, in particular a lane recognition system, in particular a video camera and / or further vehicle motion sensors, can be used.

• – durch Sensoreinrichtungen des Kraftfahrzeugs zur Erfassung des Fahrzeugumfelds ein Hindernis oder eine andere kritische Umfeldsituation erkannt wird,
• – ein Fahrerwunsch zur Deaktivierung, insbesondere mittels eines Bedienelements des Kraftfahrzeugs erfasst wird,
• – ein Fahrerlenkwunsch vorliegt, welcher dem aktuell einzustellenden Zusatzwinkel entgegen gerichtet ist, wobei ein Drehstabmoment bzw. manuelles Lenkmoment beobachtet wird,
• – ein Spurwechselmanöver durch den Fahrer mit oder ohne Betätigung eines Fahrtrichtungsanzeigers des Kraftfahrzeugs erkannt wird, und/oder
• – eine Fahrbahnkrümmung einen vorgegebenen Schwellwert überschreitet.

The continuous self-acting correction steering movements are deactivated if:

• An obstacle or another critical environment situation is detected by sensor devices of the motor vehicle for detecting the vehicle environment,
• A driver request for deactivation, in particular by means of an operating element of the motor vehicle, is detected,
• A driver steering request is present which is directed counter to the additional angle currently to be set, a torsion bar torque or manual steering torque being observed,
• - A lane change maneuver is detected by the driver with or without operation of a direction indicator of the motor vehicle, and / or
• - A road curvature exceeds a predetermined threshold.

• – ein Fahrerwunsch zur Aktivierung, insbesondere mittels eines Bedienelements des Kraftfahrzeugs erfasst wird,
• – eine geeignete Fahrzeuggeschwindigkeit vorliegt,
• – sich das Kraftfahrzeug in dem zweiten definierten Bereich befindet und sich der ermittelten Solltrajektorie annähert, und/oder
• – bei annähernder Geradeausfahrt des Kraftfahrzeugs oder bei einem Befahren von leicht gekrümmten Streckenabschnitten.

The continuous self-acting correction steering movements are activated when:

• A driver request for activation, in particular by means of an operating element of the motor vehicle, is detected,
• - there is a suitable vehicle speed,
• - The motor vehicle is in the second defined area and approaches the determined target trajectory, and / or
• - At approximately straight ahead driving the motor vehicle or when driving on slightly curved sections.

• – Erkennung eines Fahrerlenkwunsches, der dem Zusatzwinkel entgegengerichtet ist, d. h. dass ein Fahrereingriff vorliegt;
• – Erkennung eines Spurwechselmanövers durch den Fahrer, mit oder ohne eine Betätigung des Blinkers; oder
• – Überschreitung einer definierten Schwelle durch die erfasste Fahrbahnkrümmung.

The activation or deactivation of the system can be initiated by the driver himself, for example with the aid of an additional operating element. In order for an activation request to be implemented, criteria such as compliance with a suitable vehicle speed, verification of the plausibility of camera signals or detection of straight-ahead driving should be fulfilled. If this is the case and the vehicle is additionally close to the determined ideal line (taking into account the lane offset), the angular control of the function can begin. The shutdown of the function by the driver can be implemented immediately. In addition, further criteria for automated shutdown can be monitored so that if necessary, angle interventions by the driver are terminated. If one of the following criteria has occurred, a harmonic shutdown of the system can be achieved, for example by holding the last applied additional angle and then slowly reducing it in the course of the further journey:

• - Detecting a driver's steering request, which is opposite to the additional angle, ie that there is a driver intervention;
• - Detection of a lane change maneuver by the driver, with or without an operation of the turn signal; or
• - Exceeding a defined threshold by the detected road curvature.

The continuous automatic correction steering movements can be overridden by the driver. Accordingly, the corrective measures of the angle controller can only be so high that they can be deflected by the driver at any time.

According to the invention, it can be provided that the driver behavior is continuously monitored and evaluated.

To ensure user acceptance of the function, an observation of driver behavior may be required. Information about the driver's request can be identified by his requirements on the steering wheel. Suitable parameters are the steering wheel angle, the steering wheel angular velocity and above all the applied steering torque. With the help of this information can be identified in a timely manner, whether a steering request of the driver is in the opposite direction to the determined additional angle. In this case, strategies for parameterizing the System or even required for complete shutdown.

Claim 19 specifies an electronic control and regulating device of a motor vehicle for carrying out a tracking assistance method.

Claim 20 relates to an electronic power steering system of a motor vehicle.

The tracking assistance method according to the invention is preferably realized as a computer program on or distributed on a plurality of control devices of the motor vehicle or of the electronic power steering system, although other solutions are of course also possible. For this purpose, the computer program is stored in a memory element of the at least one control device. By processing on a microprocessor of the controller, the process is performed. The computer program can be stored on a computer-readable data carrier (floppy disk, CD, DVD, hard disk, USB memory stick or the like) or an Internet server as a computer program product and be transferred from there into the memory element of the control unit.

Advantageous embodiments and further developments emerge from the dependent claims. The following is an exemplary embodiment of the invention with reference to the drawing in principle.

Show it:

1 a simplified schematic representation of an electronic power steering system according to the invention, which is operated by a tracking assistance method according to the invention;

2 a highly simplified representation to illustrate a control concept of an LCS system;

3 a schematic representation of a possible driving trajectory in an activated LCS system;

4 a greatly simplified representation to illustrate a control concept of the tracking assistance method according to the invention;

5 a simplified diagram to illustrate the control concept of the tracking assistance method according to the invention;

6 a simplified block diagram for illustrating the determination of a lane offset in the context of the tracking assistance method according to the invention;

7 a simplified diagram to illustrate the determination of a lane offset within a tracking assistance method according to the invention; and

8th a simplified block diagram to illustrate the tracking assistance method according to the invention.

Like reference numerals designate functional elements in the different figures. The invention is described below with reference to a combination of an EPS steering system with a superposition steering system. Alternatively, of course, a Steer by wire steering system with the necessary changes can be used.

1 shows an inventive electronic power steering system 1 one in 2 shown motor vehicle 20 , The electronic power steering system 1 has a steering wheel 2 trained steering handle on. The steering wheel 2 is via a cardan shaft or steering column 3 with a steering gear 4 connected. The steering gear 4 serves to a rotation angle δ _{LS of} the steering column 3 in a wheel steering angle δ _Fm of steerable wheels 5a . 5b of the motor vehicle 20 implement. The steering gear 4 has a rack 6 and a pinion 7 on, to which the steering column 3 attacks. The electronic power steering system 1 also includes overlay means 8th one as an electric motor nine trained actuator or additional angle adjuster and driven by this superposition gear 10 exhibit. The superposition gearbox 10 is designed as a planetary gear. In further embodiments, the superposition gear could 10 Also be designed as a wave gear or the like. Through the steering wheel 2 becomes a steering wheel angle 6s as a measure of a desired wheel steering angle δ _{Fm of} the steerable wheels 5a . 5b of the motor vehicle specified. With the help of the electric motor nine Then, a superposition angle or additional angle δ _{M is} generated and by the superposition gear 10 with the steering wheel angle δ _S and the rotational angle δ _{LS of} the steering column 3 superimposed. The additional angle δ _M is basically to improve the driving dynamics of the motor vehicle 20 or comfort generated. The sum of steering wheel angle δ _S and additional angle δ _M gives the input angle of the steering gear 4 or in the present embodiment, the pinion angle δ _G. The overlay means 8th have an electronic control unit 11 on, which among other things, the control of the additional angle δ _M and the output torque of the electric motor nine serves. On the electronic control unit 11 For this purpose, a regulatory procedure takes place, which serves as a regulatory structure or as Computer program on a microprocessor, not shown, of the controller 11 is executed. The electric motor nine is with an electrical drive signal δ _Md , which the setpoint of the electric motor nine to be generated additional angle δ _M corresponds, driven.

The control or regulation of the electric motor nine usually takes place as a function of the vehicle speed of the motor vehicle 20 , ie the gear ratio between the steering wheel angle δ _S and the pinion angle δ _G and the wheel steering angle δ _{Fm of} the wheels 5a . 5b is set by the superimposition of the steering wheel angle δ _S with different, speed-dependent additional angles δ _M as a function of the vehicle speed. This makes it possible, for example, at low vehicle speeds to specify a relatively small gear ratio, in which a relatively small rotation of the steering wheel 2 to a relatively large wheel steering angle δ _{Fm of} the wheels 5a . 5b leads. It is also conceivable for reasons of stability at high vehicle speed to specify a relatively large transmission ratio. So that the above-mentioned control functions can be performed, receives the control unit 11 among other things, as an input signal, the current vehicle speed (eg, via a CAN bus of the motor vehicle).

The overlay means 8th downstream, has the electronic power steering system 1 an electric servo drive 12 on, which among other things serves the variable moment assistance. The electric servo drive 12 has an electric motor 13 for the realization of the torque support via a belt transmission 14 on. The belt transmission 14 has a drive pinion and a pulley for transmitting the torque assist via a recirculating ball gear (not shown) on the rack 6 of the electric power steering system 1 on. Furthermore, there is an electronic control unit 15 for controlling or regulating the electric motor 13 intended. The invention is based on an electric power steering system 1 with a belt transmission 14 and a separate recirculating ball gear for transmitting the assisting force to the rack 6 , such as from the DE 100 52 275 known, described. For other electric power steering system technologies with torque or steering assistance, the same implementations according to the invention can be achieved.

In addition, the electronic power steering system has 1 sensors 16a . 16b . 16c on, which measure the steering wheel angle δ _S , the additional angle δ _M and the pinion angle δ _G or provide equivalent signals from which these angles δ _S , δ _M , δ _G can be determined, the pinion angle δ _G also from the steering wheel angle δ _S and the additional angle δ _M can be calculated. Furthermore, a steering torque sensor is provided (not shown). The controllers 11 . 15 obtain the results of the above-mentioned sensors as input signals for further processing or control or regulation of the electric motors nine . 13 ,

2 shows a simplified representation to illustrate a control concept of an LCS system. The car 20 drives on a lane 21 , The lane 21 indicates left and right lane edges or lane edges 21a and 21b on. In the area of the left side of the road 21a is a side strip 22a and in the area of the right-hand edge of the road, a median strip 22b indicated. How farther 2 it can be seen on a vertical axis, the rule intensity I and on a horizontal axis the track deviation .DELTA.y of the motor vehicle 20 applied. A curve of the intensity I of one or more on the steering wheel 2 of the motor vehicle 20 applied additional hand moments in the direction of a middle 23 the recorded traffic lane 21 of the motor vehicle 20 as steering recommendations to assist a driver 30 (please refer 8th ) in the tracking in the context of an LCS system or even a tracking assistance method according to the invention is denoted by K1 and in 2 indicated by dashed lines. In a free space area 24 no above-mentioned additional hand moments are set and the rule intensity I is at least approximately zero.

In 3 is a lane 21 with a possible driving trajectory 25 (shown in simplified form) in an activated LCS system. The curves 25a . 25b indicate steering recommendations of the LKS system to the left or right. The middle 23 the lane 21 can also be used as a target trajectory 26 be executed.

4 shows a highly simplified representation to illustrate a control concept of the tracking assistance method according to the invention. The tracking assistance method according to the invention for the motor vehicle 20 with the electronic power steering system 1 , supports the driver 30 of the motor vehicle 20 on the one hand by one or more on the steering wheel 2 of the motor vehicle 20 applied additional hand moments in Direction of the middle 23 the recorded traffic lane 21 as steering recommendations in tracking. In addition, the driver becomes 30 of the motor vehicle 20 when driving along the determined target trajectory 26 supported such that minor lateral deviations .DELTA.y of the motor vehicle 20 from the target trajectory 26 be continuously corrected by automatic correction steering movements. In this case, a calculated target wheel steering angle is adjusted, which is the motor vehicle 20 at least approximately on the desired trajectory 26 holds. The additional hand moments towards the middle 23 the recorded traffic lane 21 be by means of the servo drive 12 of the electronic power steering system 1 adjusted for torque support. The automatic correction steering movements are from the overlay means 8th of the electronic power steering system 1 performed, with the superposition means 8th to correct a corresponding additional angle δ _M by the additional angle adjuster nine generate and the steering wheel angle δ _{S of} the driver 30 overlap with the additional angle δ _M.

The additional hand moments towards the middle 23 the lane 21 are essentially in a first defined area 27 the recorded traffic lane 21 applied, wherein the automatic correction steering movements substantially in a second defined area 28 the lane 21 around the target trajectory 26 be performed. The second defined area of the recorded traffic lane 21 can also be the free space 24 in which no additional hand moments towards the middle 23 the lane 21 be generated. The two areas 27 . 28 Of course, they can overlap.

How out 4 can be seen, the rule intensity I of Zusatzhandmomente according to the curve K1 in the second defined area 28 the recorded traffic lane 21 low and rising towards the first defined area 27 to the edge of the road 21a . 21b at. Furthermore, the controller intensity I for the automatic correction steering movements according to a curve K2 in the second defined area 28 the recorded traffic lane 21 high and increases with increasing lateral deviation Δy of the motor vehicle 20 from the target trajectory 26 towards the first defined area 27 the recorded traffic lane 21 successively from. For example, the first defined area 27 the recorded traffic lane 21 ± about 30 cm to about 40 cm around the middle 23 the recorded traffic lane 21 and the second defined area 28 the recorded traffic lane 21 each on both sides about 20 cm to about 30 cm from the lane edge 21a . 21b towards the middle 23 the recorded traffic lane 21 extend.

The controller parameters for the control of the automatic corrective steering movements and / or the additional manual torques in the direction of the center 23 the lane 21 are running, in particular as a function of the current lateral deviation Δy of the motor vehicle 20 from the target trajectory 26 and / or the current vehicle speed, customizable.

As primary controller parameters for the automatic correction steering movements or the target wheel steering angle to be adjusted, one of signals of sensor devices of the motor vehicle 20 to determine the vehicle environment detected lateral toe deviation .DELTA.y relative to the desired trajectory 26 , a lateral track speed, a relative yaw angle and / or a radius of the detected traveled lane 21 used. As secondary control parameters for the automatic correction steering movements, a yaw rate, a lateral acceleration and / or a slip angle can be used.

The determination of the required additional angle δ _M to compensate for an existing lane deviation Δy can be based on various approaches. In contrast to a simple LKS system, with the help of additional moments a steering recommendation for the driver 30 in the direction of the lane center 23 offers, is the driver 30 at the correction interventions according to the invention outside the control loop. The underlying control system must therefore be able to with a stationary steering wheel 2 the vehicle 20 to the target trajectory 26 to lead and to hold these. Its quality is characterized by an appropriate choice of the control concept as well as the controller parameters, which have to make a compromise between the dynamics of the interventions and the accuracy of the control, in particular with regard to the system acceptance. For the design of the controller, a model-based approach is pursued. Since only slight lateral accelerations occur when driving straight ahead on motorways, vehicle behavior is reproduced with sufficient accuracy by a linear single-track model of a vehicle. For this purpose, z. B. " Föllinger, O; (1994); Control technology; Hüthig book publishing house; Heidelberg "Directed. Based on the model equations shown there, different control concepts can be realized. The following investigations are based on a state controller with an integrator component. For an insight into the dynamics of the controller, shows 5 the step response of the system with an associated course of the manipulated variable. The command variable is the track deviation .DELTA.y, whose course is denoted by K3, which at the time i = 1 s has a jump of one meter. The course of the setpoint deviation is designated K4. The in 5 shown course K5 of the additional angle δ _M is limited neither in its amplitude nor in its gradient.

6 illustrates the principle of lane offset determination, which is a combined variant of long-term offset determination 17 and short-term offset determination 18 composed. Here, a long-term lane deviation Δy _long and a short-term lane deviation Δy are determined _briefly and in a module 19 to the lane offset determination together with the actual determined actual lane deviation in a desired lane deviation or a determined lateral offset Δy _soll transferred.

7 shows a graph of the courses of the lane deviations .DELTA.y _long , .DELTA.y _short , .DELTA.y _soll , .DELTA.y _is in a short-term position change P1 and a long-term position change P2 within the lane 21 , In the short-term position change P1 is a by a double arrow 29a _briefly, indicated amount of the difference Ay - Dy occurs _long less than a predetermined threshold Δ _boundary, whereby no change of Dy _to. In the long-term position change P2 is a by a double-headed arrow 29b indicated amount of difference Δy _short - Δy _long greater than or equal to a limit Δ _limit , with a change of Δy soll _is made.

Finally shows 8th a simplified block diagram to illustrate the tracking assistance method according to the invention. A driver of the motor vehicle 20 , which adjusts the steering wheel angle δ _S , is denoted by the reference numeral 30 indicated by dashed lines. The reaction of the motor vehicle 20 is denoted by x, which is also from a lane detection system 40 For example, a video camera or the like is detected for tracking. In a module 41 for the AFS angle control of the automatic correction steering movements within the method according to the invention are also a module 41a for trajectory planning, a regulatory system 41b , a monitoring module 41c for the behavior of the driver 30 and a module 41d accommodated for testing the switch-on and switch-off criteria. The EPS torque control with steering recommendations is in 8th not shown.

LIST OF REFERENCE NUMBERS

1

Electronic power steering system

2

steering wheel

3

Drive shaft / steering column

4

steering gear

5a, 5b

steerable wheels

6

rack

7

pinion

8th

Superimposing means

9

Additional angle actuator / motor

10

Superposition gear

11

Electronic control device of the superposition means

12

Electric servo drive

13

electric motor

14

belt transmission

15

Control unit of the servo drive

16a, 16b, 16c

sensors

17

Short-term offset determination

18

Long-term offset determination

19

Module for lane offset determination

20

motor vehicle

21

lane

21a, 21b

road edges

22a

shoulder

22b

central reservation

23

Middle of the lane

24

Clearance region

25

driving trajectory

26

target trajectory

27

First defined area

28

Second defined area

29a, 29b

double arrows

30

driver

40

Camera for track recognition

41

Module for AFS angle control

41a

Module for trajectory planning

41b

control system

41c

Monitoring module for the behavior of the driver

41d

Module for testing the switch-on and switch-off criteria

I

rule intensity

K1

Curve of the control intensity of the torque control

K2

Curve of the control intensity of the angle control

K3-K5

Time course of the lane deviations

P1, P2

position change

Dy

Lane deviation / lateral deviation

Δy _long

short-term track deviation

Δy _short

long-term lane departure

Δy _is

Actual tracking error

Δy _should

Target tracking error

Δ _limit

Limit value of the lane deviation

δ _Fm

Wheel steering angle or steering angle

δ _G

pinion angle

δ _S

steering wheel angle

δ _M

additional angle

δ _Md

Setpoint of the additional angle

δ _LS

Angle of rotation of the steering column

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102004039142 A1 [0004]
• DE 102007043912 A1 [0005]
• DE 19751125 A1 [0006]
• DE 10013711 A1 [0007, 0007]
• DE 10052275 [0047]

Cited non-patent literature

• Föllinger, O; (1994); Control technology; Hüthig book publishing house; Heidelberg [0056]

Claims (21)

Tracking assistance method for a motor vehicle ( 20 ) with an electronic power steering system ( 1 ), which the driver ( 30 ) of the motor vehicle ( 20 ) by one or more on a steering handle ( 2 ) of the motor vehicle ( 20 ) applied additional hand moments in the direction of the middle ( 23 ) of a recorded traffic lane ( 21 ) as steering recommendations in the tracking supported, and which the driver ( 30 ) of the motor vehicle ( 20 ) additionally while driving along a determined target trajectory ( 26 ) such that minor lateral deviations (Δy) of the motor vehicle ( 20 ) of the desired trajectory ( 26 ) are continuously corrected by automatic correction steering movements, which adjust a calculated target wheel steering angle, which the motor vehicle ( 20 ) on the target trajectory ( 26 ) holds. Tracking assistance method according to claim 1, characterized in that the additional manual torques in the direction of the center ( 23 ) of the recorded traffic lane ( 21 ) by means of a servo drive ( 12 ) of the electronic power steering system ( 1 ) are adjusted for torque support. Tracking assistance method according to claim 1 or 2, characterized in that the automatic correction steering movements of superposition means ( 8th ) of the electronic power steering system ( 1 ), which a Zusatzwinkelsteller ( nine ), the superposition means ( 8th ) to correct a corresponding additional angle (δ _M ) by the additional angle plate ( nine ) and the steering wheel angle (δ _S ) of the driver ( 30 ) with the additional angle (δ _M ). Tracking assistance method according to claim 1, 2 or 3, characterized in that the additional hand moments in the direction of the mute ( 23 ) of the lane ( 21 ) substantially in a first defined area ( 27 ) of the recorded traffic lane ( 21 ) are applied and / or that the automatic corrective steering movements essentially in a second defined area ( 28 ) of the lane ( 21 ) around the desired trajectory ( 26 ) be performed. Tracking assistance method according to one of claims 1 to 4, characterized in that the second defined area ( 28 ) of the recorded traffic lane ( 21 ) a free space ( 24 ), in which no additional hand moments in the direction of the middle ( 23 ) of the lane ( 21 ) be generated. Tracking assistance method according to one of claims 1 to 5, characterized in that the controller parameters for the regulation of the automatic correction steering movements and / or the additional manual moments in the direction of the center ( 23 ) of the lane ( 21 ), in particular as a function of the current lateral deviation (Δy) of the motor vehicle ( 20 ) of the desired trajectory ( 26 ) and / or the current vehicle speed are customizable. Tracking assistance method according to one of Claims 1 to 6, characterized in that the control intensity (I) of the additional manual torques in the second defined range ( 28 ) of the recorded traffic lane ( 21 ) is low and towards the first defined area ( 27 ) right up to the roadside ( 21a . 21b ) increases. Tracking assistance method according to one of claims 1 to 7, characterized in that the control intensity (I) for the automatic correction steering movements in the second defined area ( 28 ) of the recorded traffic lane ( 21 ) is high and with increasing lateral deviation (Δy) of the motor vehicle ( 20 ) of the desired trajectory ( 26 ) towards the first defined area ( 27 ) of the recorded traffic lane ( 21 ) decreases gradually. Tracking assistance method according to one of claims 4 to 8, characterized in that the first defined area ( 27 ) of the recorded traffic lane ( 21 ) each on both sides about 20 cm to about 30 cm from the lane edge ( 21a . 21b ) in the direction of the middle ( 23 ) of the recorded traffic lane ( 21 ) and that the second defined area ( 28 ) of the recorded traffic lane ( 21 ) ± approx. 30 cm to about 40 cm around the middle ( 23 ) of the recorded traffic lane ( 21 ) is located. Tracking assistance method according to one of claims 1 to 9, characterized in that as a primary control parameter for the automatic correction steering movements one of signals from sensor devices ( 40 ) of the motor vehicle ( 20 ) for detecting the vehicle surroundings, lateral track deviation (Δy) relative to the desired trajectory ( 26 ), a lateral track speed, a relative yaw angle of the motor vehicle ( 20 ) and / or a radius of the detected traveled lane ( 21 ) be used. Tracking assistance method according to one of claims 1 to 10, characterized in that as secondary control parameters for the automatic correction steering movements a yaw rate, a lateral acceleration and / or a slip angle of the motor vehicle ( 20 ) be used. Tracking assistance method according to one of claims 1 to 11, characterized in that one of the driver ( 30 ) more preferably, in particular short-term and / or long-term lateral Offset (Δy _long , Δy _short ) from the center ( 23 ) of the recorded traffic lane ( 21 ), evaluated in its time course and continuously in the determination of the target trajectory ( 26 ) is taken into account. Tracking assistance method according to one of claims 1 to 12, characterized in that the continuous automatic correction steering movements at least approximately straight ahead driving of the motor vehicle ( 20 ) or when driving on slightly curved sections. Tracking assistance method according to one of claims 1 to 13, characterized in that for determining the desired trajectory ( 26 ) Sensor devices of the motor vehicle ( 20 ) for detecting the vehicle environment, in particular a lane recognition system ( 40 ), in particular a video camera and / or other vehicle motion sensors are used. Tracking assistance method according to one of claims 1 to 14, characterized in that the continuous automatic correction steering movements are deactivated if: - by sensor devices ( 40 ) of the motor vehicle ( 20 ) an obstacle or another critical environment situation is detected for detecting the vehicle environment, - a driver request for deactivation, in particular by means of an operating element of the motor vehicle ( 20 ) is detected, - a driver steering request is present, which is opposite to the currently set additional angle (δ _M ), - a lane change maneuver by the driver ( 30 ) with or without operation of a direction indicator of the motor vehicle ( 20 ) is detected, and / or - a road curvature exceeds a predetermined threshold. Tracking assistance method according to one of claims 1 to 15, characterized in that the continuous automatic correction steering movements are activated when: - a driver request for activation, in particular by means of an operating element of the motor vehicle ( 20 ), - a suitable vehicle speed is present, - the motor vehicle ( 20 ) in the second defined area ( 28 ) and the determined desired trajectory ( 26 ) approximates, and / or - at approximately straight-ahead driving of the motor vehicle ( 20 ) or when driving on slightly curved sections. Tracking assistance method according to one of claims 1 to 16, characterized in that the continuous automatic correction steering movements by the driver ( 30 ) are overridden. Tracking assistance method according to one of claims 1 to 17, characterized in that the driver behavior is constantly monitored and evaluated. Electronic control unit ( 11 . 15 ) of a motor vehicle ( 20 ) for carrying out a tracking assistance method according to one of claims 1 to 18. Electronic power steering system ( 1 ) of a motor vehicle ( 20 ), with - a steering handle ( 2 ) for specifying a steering wheel angle (δ _S ) as a measure of a desired wheel steering angle (δ _Fm ) for at least one steerable wheel ( 5a . 5b ) of the motor vehicle ( 20 ), - a steering gear ( 4 ), which determines the steering wheel angle (δ _S ) in the wheel steering angle (δ _Fm ) of the at least one steerable wheel ( 5a . 5b ) of the motor vehicle ( 20 ), - an electric servo drive ( 12 ), and - overlay means ( 8th ) for generating an additional angle (δ _M ) by an additional angle adjuster ( nine ) and for generating an input angle (δ _G ) of the steering gear ( 4 ) from a superposition of the steering wheel angle (δ _S ) with the additional angle (δ _M ), wherein the electronic power steering system ( 1 ) or the additional angle plate ( nine ) and the electric servo drive ( 12 ) are operated by a tracking assistance method according to one of claims 1 to 18. Electronic power steering system according to claim 20, characterized in that the additional angle plate ( nine ) and the electric servo drive ( 12 ) by at least one electronic control unit ( 11 . 15 ) of a motor vehicle ( 20 ) on which the tracking assistance method according to one of claims 1 to 18 is executed.

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