DE102007002265A1 - Method for navigating vehicle from one position to another, involves determining travel trajectory for reaching one position depending on which position of vehicle target steering angle is determined - Google Patents

Abstract

The method involves determining a travel trajectory for reaching one position depending on which the position of target steering angle of a vehicle (1) is determined. An effective steering angle is determined by passing through the trajectory, and the difference of the effective steering angle from the target steering angle is determined continuously. The change in speed of the value of the difference of effective steering angle from the target steering angle is determined and that the control of the longitudinal speed of the vehicle is carried out depending on the change in speed.

Description

The Invention is in the field of so-called parking aids or Parking assistants, that is automatic devices in motor vehicles that assist the driver in his motor vehicle from a first position, for example on a Lane to a second position within a parking space bring to.

there are comfortable measuring systems known to support by means of distance sensors or cameras the parking space measure and also the current distance of your own vehicle from Monitor obstacles at all times. A warning system can then cause the driver to decelerate the vehicle or the Change steering angle before the vehicle collides with an obstacle.

Parking systems are also known from the prior art in which a desired trajectory for the vehicle is predicted in order to reach a position in the parking space ( US 5742141 ) and steering instructions are given to the driver. There are also systems, for example from the US 5661650 and JP 2001 138941 in which the speed of a motor vehicle is dependent on a curve radius to be maintained or is automatically controlled or limited when parking as a function of a maximum steering speed to be maintained.

Thereby For example, prevents the driver when parking the Steering wheel must turn too fast or that this by an automatic Steering is turned too fast and thus a risk of injury represents for the driver.

From the DE 10 2004 054 437 A1 a method for automatically controlling and / or regulating a movement of a vehicle during a parking operation and a corresponding automatic parking system is known. With the known system, a target trajectory for the parking operation between a first position and a second position is calculated in advance and then either automatically in a fully automatic parking operation, the corresponding steering angle depending on the movement on the target trajectory changed, in one embodiment also the control of the longitudinal movement in dependence on the derivation of a transverse movement parameter, for example, the steering angle is made.

In Another embodiment of the parking process, it is from the mentioned font known to leave the steering movement to the driver and longitudinal movement parameters of the vehicle, that is especially to control the speed automatically. Thereby in particular, the need for too fast steering movements be avoided.

at Deviations from nominal transverse movement parameters, for example a Target steering angle of the current actual steering angle is in accordance with the Prior art, the vehicle automatically stopped or delayed and it waits until the driver again set a suitable steering angle Has.

The The present invention relates to a method of controlling of a motor vehicle from a first position to a second Position under manual operation of the steering by a Driver, whereby a driving trajectory is determined, depending on determined from the position of the vehicle target steering angle, when driving through the trajectory current actual steering angle detected be and continuously the difference of the current actual steering angle from Target steering angle is determined.

Of the Invention is based on the object with such methods a certain fault tolerance with respect to the steering movements the driver as uniform as possible travel movement to enable.

The The object is achieved according to the invention that the rate of change of the amount Difference of the actual steering angle is determined by the target steering angle and that the control of longitudinal velocity in dependence from the rate of change.

By the solution according to the invention will not only the deviation of the actual steering angle from the target steering angle for the control of longitudinal motion used, which occasionally could lead to an abrupt deceleration movement, when the steering deviation becomes too big, but it becomes the tendency the steering angle difference, that is the fact whether the driver through his current steering movements the actual steering angle approaches or departs from the desired steering angle.

approaches If it adjusts to the desired steering angle, it is possible to by continuous adaptation of the trajectory in a flowing Movement despite the current deviations the desired End position, that is to reach the second position. In this case, due to the steering error, there is no reason to slow the vehicle down a lot.

By his steering movement, the driver removes the actual steering angle from the target steering angle, the means that it deviates more and more from the target value in the orientation of the vehicle, so the chances of achieving the second position decrease even when recalculating the trajectory rapidly and a deceleration of the vehicle and a realignment or at least a change in the steering movement should be made.

The means: the amount increases Difference of the actual steering angle from the target steering angle, so is the rate of change the difference in the amount is positive the vehicle braked, normally only slowed down, in the extreme Case brought to a standstill.

decreases the difference between the actual steering angle and the target steering angle in absolute terms, that is, the rate of change Negative, the vehicle is braked only when others of the difference in steering angle various parameters require this. It could also be claimed that the rate of change below a certain predetermined value is this sequence to reach. The other parameters mentioned can be, for example given by the minimum distance to obstacles in the driving environment be or by other events, necessarily stopping or Dodge the motor vehicle require.

In In any case, it is advantageous if the direction in which an actuator for vehicle steering, that is, for example a steering wheel is to be moved, the driver is informed continuously. This can be done by acoustic or tactile signals or by means an optical display.

Advantageous is also communicated to the driver when the target steering angle is reached is, that is, actual steering angle and target steering angle coincide.

Around in case of deviations of the actual steering angle of target steering angles the current Opportunities for reaching the second position and the For this purpose, to determine necessary steering movements, it is advantageous if, as a function of the course of the journey, new trajectories are constantly in progress be calculated which lead to the achievement of the second position and if each of the current target steering angle from the last determined Trajectory is determined.

By This procedure can be constantly adjusting the trajectory be made so that in case of deviations the vehicle is not necessarily attributed to the initially calculated trajectory which may require major adjustments but adapted to one in the meantime possible trajectory caused by lower steering movements can be reached from the actual state.

By The constant recalculation of trajectories can also be ensured be recognized that, if due to the limits of maneuverability to achieve the second position no trajectory more determinable is. In this case, namely the journey is abort and if necessary, to make a new approach. It can be for this Case be provided that the motor vehicle in the previously calculated Trajectory opposite direction is set in motion again, to reach a position of the vehicle, from there again one Trajectory can be determined on which the second position can be reached is.

It can also be advantageously provided that the motor vehicle for Standstill is slowed down as soon as it becomes apparent that a feasible Trajectory between the actual position of the motor vehicle and the desired second position only by setting a the greatest possible steering angle at the currently occupied point of the trajectory is still achievable.

In In this case, wait until the driver reaches the maximum steering angle has set and only then can the vehicle on the trajectory be started again. This ensures that the Vehicle can not get into a position from which the second Position without change of direction is no longer available.

It can also be provided that the motor vehicle is braked, if it is determined that the maximum necessary steering angle the precalculated trajectory varies from recalculation to recalculation the trajectory increases and currently a difference exists between actual steering angle and target steering angle.

By This embodiment of the method ensures that the Vehicle is kept on trajectories where possible low steering angles are necessary. This enlarges the comfort while traversing the trajectory and reduces the demands on the driver, what the steering movements As.

in the The invention is based on an embodiment shown in a drawing and then described.

there shows:

1 a schematic view of a vehicle from above with different set steering angles;

2 a trajectory of a vehicle when parking backwards;

3 in the upper part the behavior of the target steering angle and an actual steering angle along the trajectory, in the lower part a resulting deceleration.

1 shows a schematic view from above of a vehicle 1 with two front wheels 2 . 3 in three steering positions and with two rear wheels 4 . 5 ,

The arrows 2a . 2 B . 2c and 3a . 3b . 3c denote the various steering directions shown in the alternatives, by means of actuation of the steering wheel 6 manually adjustable. This designates 2a each straight ahead, 2 B an impact by a steering angle φ1 to the right and 2c . 3c a steering angle by an angle φ2 to the right. The difference between the steering angle φ1 and the steering angle φ2 is denoted by Δφ.

The currently set steering directions 2a . 2a . 2c . 3a . 3b . 3c be using sensors 7 . 8th to a control unit 9 reported.

The control unit 9 also receives data from various sensors of the vehicle, such as rear range sensors 10 . 11 and a side-facing camera 12 , which serves to detect the space lying laterally next to the vehicle and to detect and measure parking spaces.

The camera is operated, for example, when looking for a parking space while driving past a number of vehicles at the edge of the vehicle and continuously captures images of the driving environment on the right side in the direction of travel next to the vehicle 1 , If a suitable parking space is detected, the position of the vehicle relative to the parking space is detected by calculating the instantaneous steering angle and with the aid of the current detection of the driving speed or the distance traveled.

If the detected parking space to be approached, then, as in 2 shown, an optimal trajectory 13 for the vehicle 1 for entering the parking space to the second position 14 calculated. Meanwhile, the vehicle is still in the first position in which it is shown in the figure.

If the parking operation should be started, this can be done by the driver starting the process by pressing the accelerator pedal or by pressing a button. The vehicle thus sits down along the trajectory 13 moving.

The driver is informed by means of the display unit 15 informed in which direction he should turn the steering wheel. Upon reaching the desired steering angle φ, for example, an acoustic signal can be given. The driver must constantly track the steering angle during the parking process.

It is not enough that there are deviations of the actual steering angle from the target steering angle. These can normally be corrected later, in that the control unit 9 a new trajectory calculated from the instantaneous position of the vehicle, which moves the vehicle to the second position 14 leads.

It however, it can happen that the vehicle is moving so fast that it drives too far than that by steering it in yet the parking space could be moved as the maximum Steering angles are limited. In this case, the vehicle must stopped and moved back to the starting position.

Around to prevent this is provided according to the invention, that in the areas of motion in which the actual steering angle deviates from the target steering angle and this deviation noticeably greater is, the vehicle is decelerated to the deviation from the first calculated trajectory as small as possible. This increases the probability that even after the deviation from the desired trajectory nor a new possible trajectory can be calculated.

in principle Also, the speed of the vehicle during the entire parking process to a certain maximum speed be limited to the steering angle speeds provided by the driver be required on the operation of the steering wheel on to limit a reasonable amount.

It can also be provided that in the event that an achievable Trajectory just can be calculated, the vehicle up is stopped and then in the state of the driver Actual steering angle to a desired steering angle can correct to instantaneous to get to the new, just mobile, trajectory,

For deceleration or deceleration until the vehicle is at a standstill 1 serve braking elements 16 . 17 passing through the control unit 9 are responsive.

In the control unit 9 is thus due to the example by the camera 12 or other sensors collected data computes a desired trajectory defined by a travel path and associated desired steering angles.

Thereafter, during the Durchfah the trajectory of the set actual steering angle compared with the target steering angle and the tendency of the angular difference Δφ analyzed.

If the angular deviation of the actual steering angle from the target steering angle increases in magnitude, the control unit acts 9 on the brake elements 16 . 17 one.

It can also be provided that, after the difference of the actual steering angle has been reduced again from the target steering angle, the control unit 9 acting on acceleration elements of the vehicle.

It However, it is also conceivable that accelerating by the driver Actuation of the accelerator pedal is effected.

In the 3 the traversed length L of the trajectory is shown in the upper part of the figure on the x-axis. On the y-axis of the target steering angle φ is removed as a solid line. The target steering angle increases in the first part of the movement or the parking process from point L1 to point L2. The vehicle is tilted in this area to be driven into the parking space. During the entry into the parking space, the steering deflection is then reduced again to 0 at point L3. In this area of movement, the vehicle drives obliquely into the parking space.

Thereafter, the steering in the opposite direction must be taken to the vehicle in the second position 14 align again parallel to the initial position. The opposite direction starts at point L4. At point L5, the final alignment of the vehicle is reached and the steering is again neutral, that is, at a steering angle 0.

In the figure is a dashed real steering behavior in the form of actual steering angles entered.

The steering behavior in the illustrated parking process is characterized by the fact that from the point L1 initially the steering is not taken. The vehicle thus drives a little way past the parking space. The steering is taken only shortly before reaching the point L2 and that with a very fast change in steering angle. At this time is already through the control unit 9 a new trajectory has been calculated, which must be observed in order to drive the vehicle into the parking space.

In order not to allow the vehicle to pass too far past the parking space in the area after passing through the point L1, the deviation of the actual steering angle from the target steering angle, which becomes clear in the upper figure area as a vertical distance between the solid and the dashed line , from the control unit 9 registered and depending on the tendency of this deviation, a braking acceleration is effected.

Since in the area behind the point L1, the difference in the steering angle increases rapidly, the vehicle is decelerated there, which in the lower part of 3 through the bend 18 is shown.

At point L3, when the vehicle is properly aligned and should enter the parking space more or less straight ahead, in the actual driving operation, a steering angle takes place in the opposite direction as indicated by the dashed line segment 19 is shown. This means that the vehicle has not moved far enough into the parking space to initiate the countersteering operation.

Consequently, the vehicle is decelerated again to minimize the deviation from the previously calculated target trajectory. At the same time, a new trajectory is calculated. The steering is along the dashed line 20 Aligned again, with a little overshoot 21 to compensate for the error. Thereafter, the vehicle can in the desired second position 14 be driven. To the point L6 is again by braking acceleration, represented by the curve 22 , the vehicle finally brought to a halt.

The dashed curve piece 23 shows a steering behavior in which the vehicle is maneuvered into a position from which it is not without a new approach to the second position 14 can be brought. The wrong steering angle adjustment is not corrected in time so that no possible trajectory can be calculated to reach the final position without reversing the vehicle. In this case, the vehicle must be braked to a standstill and moved out in the opposite direction at least a little bit from the parking space again. The corresponding braking acceleration is not shown in the lower part of the figure for the sake of clarity.

Due to the fact that the invention does not exclusively register distances from a desired trajectory during the parking process, but is based on the more complex variable, namely the change tendency of the difference of the actual steering angle from a desired steering angle, the vehicle does not have to be at optimal steering behavior Standstill be brought, but it is only minimized by braking the vehicle, the deviation from the target trajectory and the adjustment of the steering angle with recalculation of possible Trajectories allows. As a result, a uniform parking operation is possible even with steering errors.

The corresponding actual steering angle deviation from the target steering angle is transmitted to the driver, for example, in an ad, as well as the temporal change of the steering angle deviation, so he can then correct his steering behavior.

1

motor vehicle

2, 3

front wheels

4, 5

rear wheels

2a, 2b, 2c

various steering directions

3a, 3b, 3c

various steering directions

6

steering wheel

7, 8th

sensors

9

control unit

10 11

distance sensors

12

camera

13

optimal trajectory

14

second position

15

display unit

16 17

brake elements

18

difference the steering angle

19

steering in the opposite direction

20

alignment the steering

21

Small overshoot

22

deceleration

23

steering behavior

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 5742141 [0003]
• US 5661650 [0003]
• - JP 2001138941 [0003]
• - DE 102004054437 A1 [0005]

Claims (11)

Method for controlling a motor vehicle ( 1 ) from a first position to a second position ( 14 ) under manual operation of the steering by a driver, whereby before reaching the second position ( 14 ) a driving trajectory ( 13 ) is determined, depending on the position of the vehicle target steering angle are determined when driving through the trajectory current actual steering angle are detected, and continuously the difference of the current actual steering angle is determined by the target steering angle, characterized in that the rate of change the amount of the difference of the actual steering angle is determined by the target steering angle and that the control of the longitudinal speed of the vehicle takes place in dependence on the rate of change. Method according to Claim 1, characterized in that the motor vehicle ( 1 ) is decelerated when the rate of change is positive, that is, the difference between the actual steering angle and target steering angle increases in magnitude. Method according to claim 1, characterized in that if the rate of change is negative, that is the difference between actual steering angle and target steering angle is reduced, the vehicle is braked only when others, this requires different parameters from the difference. A method according to claim 1, 2 or 3, characterized in that the direction in which an actuator for the vehicle steering is to be moved, the driver is notified. Method according to claim 3, characterized that the driver is notified when the target steering angle with the Actual steering angle coincides. Method according to Claim 1 or one of the subsequent claims, characterized in that, as a function of the course of the journey, new trajectories are continually being calculated which lead to the achievement of the desired second position ( 14 ) and that the respective desired steering angle is determined from the last calculated trajectory. Method according to Claim 1 or one of the following, characterized in that the motor vehicle ( 1 ) is braked to a standstill as soon as it is apparent that a feasible trajectory between the actual position of the motor vehicle and the desired second position ( 14 ) is only achievable by setting a maximum steering angle at the currently occupied point of the trajectory. Method according to claim 1 or one of the following characterized in that the motor vehicle is braked, if it is determined that the maximum necessary steering angle the precalculated trajectory varies from recalculation to recalculation the trajectory increases and currently a difference exists between actual steering angle and target steering angle. Method according to claim 1 or one of the following characterized in that the motor vehicle braked to a standstill becomes, as soon as it turns out, that no feasible trajectory between the Actual position of the motor vehicle and the desired second Position can be determined. Method according to claim 7, characterized in that that the motor vehicle automatically after standstill is accelerated again in the direction of the calculated trajectory, if a steering angle is set to achieve the desired end position is suitable. A method according to claim 9, characterized in that the motor vehicle is accelerated automatically after standstill in the direction opposite to the previously calculated trajectory direction, if it appears that the desired second position ( 14 ) from the assumed actual position at which the motor vehicle has stood still, is not accessible.