DE102016005739A1 - Method for determining the intrinsic motion of a vehicle - Google Patents

Abstract

The invention relates to a method for determining the proper motion of a vehicle (1) with four wheels (VL, VR, HL, HR). According to the invention, in each case a trajectory of the vehicle (1) is determined by means of all possible wheel combinations of respectively two of the four wheels (VL, VR, HL, HR), the respective trajectory being determined by means of wheel speeds (vVL, vVR, vHL, vHR ) and wheel angles (δVL, δVR, δHL, δHR) of the respective two wheels (VL, VR, HL, HR) is determined and wherein the determined trajectories are combined with an evaluation of a respective driving state of the vehicle (1) to a movement model, which Depending on the driving state describes the proper motion of the vehicle (1).

Description

The invention relates to a method for determining the intrinsic motion of a vehicle according to the features of the preamble of claim 1.

From the prior art, as in the DE 10 2012 216 213 A1 described a method for estimating tire parameters for a vehicle. In this method, a reference movement of the vehicle is measured. Based on a model exempted from the tire parameters to be estimated, a model motion of the vehicle is modeled. Based on a comparison of the reference motion and the model motion, the tire parameters of the vehicle are estimated.

The invention is based on the object to provide a comparison with the prior art improved method for determining the intrinsic motion of a vehicle.

The object is achieved by a method for determining the intrinsic motion of a vehicle having the features of claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims.

In a method for determining the intrinsic motion of a vehicle with four wheels, a trajectory of the vehicle is determined according to the invention by means of all possible wheel combinations of two of the four wheels of the vehicle, wherein the respective trajectory is determined by means of wheel speeds and wheel angles of the respective two wheels and wherein the determined trajectories are combined with an evaluation of a respective driving state of the vehicle to a movement model, which describes the vehicle's own motion depending on the state of motion.

By means of the method, the proper motion of the vehicle is thus determined by means of a vehicle-condition-dependent four-wheel odometry model of the vehicle. The method is particularly advantageous for carrying out automatic, in particular autonomous or at least partially autonomous, parking maneuvers of the vehicle, since for this the self-motion estimation is one of the most important factors. The proper movement may only be done by vehicle base sensors. Through speed sensor to determine wheel revolutions of the wheels of the vehicle can be used for proper motion odometry determination.

In order to ensure the highest possible accuracy of the odometry, as far as possible all available and suitable information is used, in particular wheel speeds and wheel angles of the four wheels of the vehicle. Since resulting differential equations that can be set up in this movement model are overdetermined and have different accuracies and errors in different driving conditions, the driving condition-dependent four-wheel odometry model is developed. For this purpose, the odometry in each driving condition is calculated by different formulas on different wheels. Only one orientation and speed of two points of the vehicle are required for the respective equation of motion. H. two wheels of the vehicle. Thereafter, all individual solutions, i. H. the trajectories determined with all wheel combinations from each two of the four wheels of the vehicle, combined with the evaluation of the driving condition of the vehicle, for example in a Kalman filter to a movement model, which depends on the driving condition and the best description of the movement of the vehicle through the information of all four wheels Vehicle based on its odometry results.

• • vorderes linkes Rad und vorderes rechtes Rad,
• • vorderes linkes Rad und hinteres rechtes Rad,
• • vorderes linkes Rad und hinteres linkes Rad,
• • vorderes rechtes Rad und hinteres rechtes Rad,
• • vorderes rechtes Rad und hinteres linkes Rad,
• • hinteres rechtes Rad und hinteres linkes Rad.

The wheel combinations from each of two of the four wheels of the vehicle are:

• • front left wheel and front right wheel,
• • front left wheel and rear right wheel,
• • front left wheel and rear left wheel,
• • front right wheel and rear right wheel,
• • front right wheel and rear left wheel,
• • rear right wheel and rear left wheel.

Possible driving conditions of the vehicle are, for example, a straight ahead with constant speed and small steering angle, a straight ahead with constant acceleration and small steering angle, cornering at constant speed and steering angle, cornering with constant acceleration and constant steering angle, cornering at a constant speed and constant steering speed and cornering with constant acceleration and constant steering speed.

For example, when driving straight ahead with constant speed and small steering angle, the wheel combination of rear right wheel and rear left wheel gives the best results with respect to the actually driven trajectory of the vehicle, while for example in cornering at constant speed and steering angle the wheel combinations of front left wheel and rear Right wheel and front right wheel and rear left wheel and when cornering with constant acceleration and constant steering angle, the wheel combinations of front left wheel and rear left wheel and front right wheel and rear right wheel the best results regarding the actually driven trajectory of the vehicle deliver. By including the respective driving state, the trajectories determined by means of the wheel combinations can thus be evaluated with respect to their accuracy with respect to the respective driving state and, according to this evaluation, weighted differently into the determination of the actual trajectory of the vehicle, ie the vehicle's own motion.

The method allows a comparison with the prior art improved self-motion estimation especially at low speeds and thus in particular a safe implementation of autonomous or at least partially autonomous parking maneuvers.

Embodiments of the invention will be explained in more detail below with reference to a drawing.

Showing:

1 schematically a self-motion of a vehicle.

1 shows in a highly schematically simplified representation of a self-motion of a vehicle 1 with four wheels VL, VR, HL, HR from a first position P1 in which the vehicle 1 shown by solid lines, in a second position P2, in which the vehicle 1 shown with dashed lines. In a method for determining the proper motion of the vehicle 1 is by means of all possible wheel combinations of two of the four wheels VL, VR, HL, HR of the vehicle 1 each a trajectory of the vehicle 1 wherein the respective trajectory is determined by means of wheel speeds v _VL , v _VR , v _HL , v _HR and wheel angles δ _VL , δ _VR , δ _HL , δ _{HR of} the respective two wheels VL, VR, HL, HR and wherein the determined trajectories with an evaluation of a respective driving state of the vehicle 1 are combined to form a movement model, which depending on the driving state, the proper motion of the vehicle 1 describes.

• • vorderes linkes Rad VL und vorderes rechtes Rad VR,
• • vorderes linkes Rad VL und hinteres rechtes Rad HR,
• • vorderes linkes Rad VL und hinteres linkes Rad HL,
• • vorderes rechtes Rad VR und hinteres rechtes Rad HR,
• • vorderes rechtes Rad VR und hinteres linkes Rad HL,
• • hinteres rechtes Rad HR und hinteres linkes Rad HL.

The wheel combinations of two of the four wheels VL, VR, HL, HR of the vehicle 1 are:

• Front left wheel VL and front right wheel VR,
• Front left wheel VL and rear right wheel HR,
• Front left wheel VL and rear left wheel HL,
• Front right wheel VR and rear right wheel HR,
• Front right wheel VR and rear left wheel HL,
• Rear right wheel HR and rear left wheel HL.

The resulting differential equations that can be established in this model of motion are overdetermined. The six wheel combinations result in six trajectories of the vehicle 1 , from which an actual trajectory of the vehicle 1 ie the proper motion of the vehicle 1 , can be determined. Since the trajectories determined by means of the wheel combinations have different accuracies and errors in different driving states, a respective driving state of the vehicle additionally becomes 1 considered.

Possible driving conditions of the vehicle 1 For example, a straight-ahead drive with constant speed and a small steering angle, a straight-ahead drive with constant acceleration and a small steering angle, a cornering drive with constant speed and constant steering angle, one Cornering with constant acceleration and constant steering angle, cornering at constant speed and constant steering speed and cornering with constant acceleration and constant steering speed.

For example, when driving straight ahead at a constant speed and a small steering angle, the wheel combination of rear right wheel HR and rear left wheel HL provides the best results with respect to the actual trajectory of the vehicle 1 while, for example, when cornering at a constant speed and constant steering angle, the wheel combinations of front left wheel VL and rear right wheel HR and front right wheel VR and rear left wheel HL and cornering with constant acceleration and constant steering angle, the wheel combinations of front left Rad VL and rear left wheel HL and from front right wheel VR and rear right wheel HR the best results regarding the actually driven trajectory of the vehicle 1 deliver.

By incorporating the respective driving state, the trajectories determined by means of the wheel combinations can thus be evaluated with regard to their accuracy with respect to the respective driving state and weighted differently in accordance with this evaluation in the determination of the actual trajectory of the vehicle 1 , ie the self-motion of the vehicle 1 , inflow. The actually driven trajectory of the vehicle's own motion 1 is then determined, for example, based on an average value of the trajectories determined by means of all wheel combinations, by means of a Kalman filter and / or by means of a fuzzy logic. For example, the trajectories determined by means of the wheel combinations with the evaluation of the driving condition of the vehicle 1 in a Kalman filter to a motion model, which is driving condition-dependent and by the information of all four wheels VL, VR, HL, HR of the vehicle 1 the best description of the movement of the vehicle 1 based on which odometry results.

As parameters for determining the trajectory by means of the respective wheel combination, the wheel angle δ _VL , δ _VR , δ _HL , δ _{HR of} the respective wheels VL, VR, HL, HR, a wheelbase w of the vehicle 1 , also called Wheelbase, a gauge T of the vehicle 1 or a respective axis of the vehicle 1 , also referred to as track, wheel speeds of the respective wheels VL, VR, HL, HR, also referred to as Radticks, and / or a rolling circumference of the respective wheels VL, VR, HL, HR used.

The information of two wheels VL, VR, HL, HR of the vehicle 1 , ie their wheel angle δ _VL , δ _VR , δ _HL , δ _HR and wheel speeds v _VL , v _VR , v _HL , v _HR , are already sufficient to describe the proper motion of the vehicle 1 , The respective wheel angle δ _VL , δ _VR can be derived for the front axle, ie for the two front wheels VL, VR, for example from a steering angle, which is detected for example by means of a steering angle sensor. For the two rear wheels HL, HR, the respective wheel angle δ _HL , δ _{HR is} usually zero, at least when the vehicle 1 has an unguided rear axle. For this reason, the wheel angles δ _HL , δ _{HR of} the two rear wheels HL, HR in 1 not shown.

The respective wheel speed v _VL , v _VR , v _HL , v _HR can be determined, for example, by means of the wheel speed and the rolling circumference of the respective wheel VL, VR, HL, HR. The rolling circumference is known. The wheel speed is determined, for example via corresponding wheel speed sensors.

The following are formulas for each wheel combination. In this case, an average velocity v _{M of} the trajectory for the respective wheel combination is calculated for the respective wheel combination from the wheel speeds v _VL , v _VR , v _HL , v _{HR of} the respective wheels VL, VR, HL, HR. Furthermore, a radius R _VL , R _VR , R _HL , R _{HR of} the two wheels VL, VR, HL, HR of the respective wheel combination is calculated for the respective wheel combination, from which then a mean radius R _{M of} the trajectory for the respective wheel combination is calculated becomes. In addition, for the respective wheel combination, an angle α of the trajectory traveled during a time interval Δt for the respective wheel combination of the vehicle 1 calculated. Thus, the trajectory determined with the respective wheel combination is described by the average radius R _M determined in each case, the average speed v _M determined in each case and the respectively determined angle α.

For the wheel combination front left wheel VL and rear right wheel VR applies:

For the wheel combination front right wheel VR and rear left wheel HL applies:

For the wheel combination front left wheel VL and rear left wheel HL applies:

For the wheel combination front right wheel VR and rear right wheel HR applies:

For the wheel combination front left wheel VL and front right wheel VR applies:

For the wheel combination rear right wheel HR and rear left wheel HL applies:

For an unguided rear axle applies to the wheel angle δ _HL , δ _{HR of} the two rear wheels: δ _HL ≈ 0 [29] δ _HR ≈ 0 [30]

For such an unguided rear axle thus applies: R _HL = R _HR + T [31]

As already mentioned above, the trajectory determined with the respective wheel combination is described by the average radius R _M determined in each case, the average speed v _M determined in each case and the respectively determined angle α. The trajectories determined in this way by means of the wheel combinations and thus the values determined for the respective wheel combination for the mean radius R _M , the average speed v _M and the angle α should be identical. Due to different accuracies, however, different values will result. By including the respective driving state, however, the trajectories determined by means of the wheel combinations can be evaluated with regard to their accuracy with respect to the respective driving state and weighted differently in accordance with this evaluation in the determination of the actual trajectory of the vehicle 1 , ie the self-motion of the vehicle 1 , inflow. The actually driven trajectory of the vehicle's own motion 1 is then, as already mentioned above, for example, based on an average of the determined by means of all wheel combinations trajectories, determined by means of a Kalman filter and / or by means of a fuzzy logic. For example, the trajectories determined by means of the wheel combinations with the evaluation of the driving condition of the vehicle 1 in a Kalman filter to a motion model, which is driving condition-dependent and by the information of all four wheels VL, VR, HL, HR of the vehicle 1 the best description of the movement of the vehicle 1 based on which odometry results.

LIST OF REFERENCE NUMBERS

1

vehicle

HL

rear left wheel

MR

rear right wheel

P1

first position

P2

second position

R _VL

from the front left wheel driven radius

R _VR

from the front right wheel driven radius

R _HL

Radius driven by the rear left wheel

R _HR

from the rear right wheel driven radius

R _M

average radius

T

gauge

VL

front left wheel

VR

front right wheel

w

wheelbase

α

angle

δ _VL

Wheel angle of the front left wheel

δ _VR

Wheel angle of the front right wheel

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 102012216213 A1 [0002]

Claims (3)

Method for determining the proper motion of a vehicle ( 1 ) with four wheels (VL, VR, HL, HR), characterized in that by means of all possible wheel combinations of two of the four wheels (VL, VR, HL, HR) of the vehicle ( 1 ) each have a trajectory of the vehicle ( 1 ), wherein the respective trajectory by means of wheel speeds (V _VL , V _VR , V _HL , V _HR ) and wheel angles (δ _VL , δ _VR , δ _HL , δ _HR ) of the respective two wheels (VL, VR, HL, HR ) and wherein the determined trajectories with an evaluation of a respective driving state of the vehicle ( 1 ) are combined to form a movement model which, depending on the driving state, determines the proper motion of the vehicle ( 1 ) describes. A method according to claim 1, characterized in that an actual movement trajectory of the proper motion of the vehicle ( 1 ) is determined on the basis of an average value of the trajectories determined by means of all wheel combinations, by means of a Kalman filter and / or by means of a fuzzy logic. Method according to one of the preceding claims, characterized in that as parameters for determining the trajectory by means of the respective wheel combination of the wheel angle (δ _VL , δ _VR , δ _HL , δ _HR ) of the respective wheels (VL, VR, HL, HR), a Wheelbase (w) of the vehicle ( 1 ), a track (T) of the vehicle ( 1 ) or a respective axle of the vehicle ( 1 ), Wheel speeds of the respective wheels (VL, VR, HL, HR) and / or a rolling circumference of the respective wheels (VL, VR, HL, HR) are used.

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