EP1257785A1

EP1257785A1 - Method and assembly for accumulating combined positional information for a system

Info

Publication number: EP1257785A1
Application number: EP00991554A
Authority: EP
Inventors: Markus Schupfner; Henning Lenz; Dragan Obradovic
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2000-02-21
Filing date: 2000-12-21
Publication date: 2002-11-20
Also published as: WO2001063209A1; US20030149524A1; CN1452714A; JP2003524170A

Abstract

The invention relates to a method and an assembly for accumulating combined positional information for a system, in which for predetermined instants first and second respective positional information of a system are determined, using a first and a second position determination system. Respective error information for at least one part of the predetermined instants is determined using the first and second positional information. The error information is used to determine a measure for a statistical dependency between the respective error information, and said measure for a statistical dependency is used to determine the combined positional information.

Description

description

Method and arrangement for forming an overall position information for a system

The invention relates to the formation of a total position information, which total position information is determined using a first position determination system and a second position determination system.

Formation of total position information is known from [1] and is used there in a navigation system for determining position information for a motor vehicle and for navigating the motor vehicle.

The navigation system known from [1] comprises two redundant position determination systems, a first and a second position determination system.

Using the first and the second position determination system, current position information, first position information and second position information are printed out for a current position of the motor vehicle, in each case printed out by a distance traveled by the motor vehicle and an orientation of the motor vehicle.

An overall position information, which describes the current position of the motor vehicle, is determined using the first position information and the second position information.

The motor vehicle is navigated using the overall position information.

The first position determination system of this navigation system consists of an odometer, with which the traveled te route of the vehicle is determined, and from a gyroscope, with which the orientation of the vehicle is determined.

The second position determination system is a so-called global positioning system (GPS), with which the distance traveled and the orientation of the motor vehicle are determined, just as with the first position determination system.

[3] discloses other different types of GPS-type systems which differ in the type of position information they determine.

When determining a current position of the motor vehicle, the current position information is used both by the first position determination system (first position information) and by the second position determination system (second position information).

The two redundant position information are compared with one another in such a way that a position difference between the first and the second position information is determined.

The current position is determined in such a way that the first position information is corrected using the second position information and the overall position information for the current position of the motor vehicle is determined therefrom.

Otherwise, the total position information for the current position of the motor vehicle is formed only from the first position information.

A caiman filter is known from [2]. The invention is based on the problem of specifying a method and an arrangement with which position information of a system can be determined with improved accuracy than in the method described above.

The problem is solved by the method and by the arrangement according to the respective independent claim.

In the method for forming an overall position format for a system, which overall position information is given under

If the use of a first position determination system and a second position determination system is determined, first position information of the system is determined using the first position determination system for predetermined times. For the predetermined times, second position information of the system is determined using the second position determination system.

For at least some of the predetermined times, error information is determined using the first and the second position information of the respective time.

A measure of a statistical dependency between the error information is determined, and the overall position information is determined using the measure of the statistical dependency.

The arrangement for forming total position information for a system, which total position information is determined using a first position determination system and a second position determination system, has a processor which is set up in such a way that - for predetermined times, first position information of the system can be determined using the first position determination system . second position information of the system can be determined for the predetermined times using the second position determination system,

for at least some of the predetermined times, a missing information can be determined using the first and the second position information of the respective time,

- A measure for a statistical dependency between the missing information can be determined and the total position information can be determined using the measure for the statistical dependency.

The arrangement is particularly suitable for carrying out the method according to the invention or one of its further developments explained below.

It should also be pointed out that a measure for a statistical dependency in the broader sense also means a statistical measure for an error. Furthermore, a measure is not just a discrete number or a discrete one

Understanding value but a measure can also be a functional description or a continuous size.

Preferred developments of the invention result from the dependent claims.

The further developments described below relate both to the method and to the arrangement.

The invention and the further developments described below can be implemented both in software and in hardware, for example using a special electrical circuit.

Furthermore, the invention or a further development described in the following can be implemented by means of a computer-readable storage medium on which a computer program stores, which carries out the invention or training.

The invention and / or any further development described below can also be implemented by a computer program product which has a storage medium on which a computer program which carries out the invention and / or further development is stored.

In order to improve the accuracy of the overall position information, error information is preferably determined for all predetermined times.

In a further development, the first and the second position information each comprise a distance covered by the system and an orientation of the system.

The first and the second position information can also each include a speed of the system.

In an embodiment in which the overall position information is determined during operation of the system, the predetermined times describe a time series.

In one development, the first position information and / or the second position information for a future point in time is / are determined using the measure for the statistical dependency. Using the first and / or the second position information for the future point in time, the first and / or the second position information is corrected for one of the predetermined points in time and the total position information is thereby formed.

To further improve the accuracy of the overall position information, the measure for the statistical is preferred

Dependence determined using a Cayman filter. In a further development, the measure for the statistical dependency is derived from a covariance matrix, which is formed using the error information.

In one embodiment, using the measure for the statistical dependency, a reliability check is carried out for the first and / or the second position information.

To improve the navigation of a system to be navigated, for example a motor vehicle, a development is used in a navigation system with which a position of the system to be navigated is determined.

In the case of an inexpensive further development, the first position determination system preferably consists of an odometer and a gyroscope.

A Global Positionmg System (GPS) is preferably used as the second position determination system.

Exemplary embodiments of the invention are shown in figures and are explained in more detail below.

Show it

Figure 1 is a sketch of a navigation system with components in a motor vehicle;

FIG. 2 shows a sketch which describes the interaction of components of a navigation system;

3 shows a sketch of method steps of a method for determining position information.

Figure 4 is a sketch of process steps according to an alternative to the exemplary embodiment. Exemplary embodiment: navigation system in a motor vehicle

1 shows a motor vehicle 100 which is equipped with a navigation system 110.

Components of this navigation system 110 are shown in FIG. 1 and FIG. 2 and are described below.

F g.2 shows the components of navigation system 110 schematically and their interaction.

The components of the navigation system 200 are each connected to one another in such a way that data which are determined or measured in the individual components can be transmitted to the other components and are available there for further processing.

The connections between the components of the navigation system 200 are represented by arrows in FIG. 2, wherein an arrow direction illustrates a direction of transmission of the data between two interconnected components.

The navigation system 200 comprises a position determination system 210, which in turn has three independent position determination systems, a GPS system 220, a gyroscope 230 and an odometer 240.

Current, first position information of a current position of the motor vehicle is determined using the gyroscope 230 and the odometer 240.

Using the GPS system 220, a second current position information, which is redundant to the first position information, is determined. Using the first and the redundant, second position information, an improved, because more accurate, current position information for the current position of the motor vehicle 100 is determined.

A digital map 250 is stored in the navigation system 200. The digital map 250 is a digitized image of an environment of the motor vehicle 100, in which traffic connections and other traffic-relevant information, for example cities, are entered.

The current position of the motor vehicle m of the digital map 250 is determined using the digital map 250 and the improved current position information of the motor vehicle 100.

The navigation system 200 has an input device 260 with which a destination position of the motor vehicle 100 can be entered by the driver of the motor vehicle 100 m the navigation system 200.

A route calculation unit 270 of the navigation system 250 uses the entered target position and the improved, current position of the motor vehicle to determine a shortest route to the target position.

It should be pointed out that an optimal route can also be determined with regard to another criterion, for example travel time.

The navigation system 200 has a display unit 280. Using the display unit 280, which comprises an optical output means 290 and an acoustic output means 291, the driver of the motor vehicle 100 is acoustically and optically shown the shortest route (or other optimal) route to the entered target position. 1 shows the gyroscope 120, the odometer 121 and the GPS 122, which are each connected to a computing unit 130 via data lines 123.

It should be noted that a data line can also be a radio link or other medium.

The digital map and a first software program described below are stored in the computing unit 130, using which the improved, current position information of the motor vehicle is determined.

A second software program is stored in the computing unit 130, with which the current position of the motor vehicle is determined on the digital map and the shortest route to the predetermined target position is determined using the current position.

1 shows the input means 140 for inputting the target position of the motor vehicle and the output means for outputting the shortest route to the target position.

3 shows method steps 300 for determining the improved current position information for the current position of the motor vehicle.

The method steps described below are carried out continuously while the navigation system 110 or 200 is in operation.

In a first method step 310, the first position information of the motor vehicle 100 is determined or measured for predetermined times k of a time series using the first position determination system, the gyroscope and the odometer.

a) Gyroscope DE0 4

10

At time k, the gyroscope measures a measured value vGyro (k). This can be used to describe the following formal relationships:

wWm (k) = [vGyro (k) - (vOGyro (k) + pl (k))] * s (k) (1)

Wl (k + 1) = Wl (k) + Wιn (k) dT = (2)

= Wl (k) + [[vGyro (k) - (vθGyro (k) + pl (k))] * s (k)] dT (3) pl (k + l) = pl (k) (4)

with: w in (...): change of angle, s (...): scaling factor, vOGyro (...): gyroscope offset,

Wl (...): alignment, pl (...): gyroscope parameters, dT: timing.

and with k and k + l, which describe a point in time (k) and a point in time (k + l) later in a time series with points in time, a time step of 0.5 sec between two points in time of the time series.

b) odometer

At time k, the odometer measures a measured value vθdo (k). This can be used to describe the following formal relationships:

wθdo (k) vθdo (k) * [t (k) + p2 (k)] * dT: 5; p2 (k + l) = p2 (k) 6)

with: wOdo (.. distance traveled, vOdo (.. speed, t (...): scaling factor, p2 (...) odometer parameters. The first position information thus includes the large Wl (k) and the large wθdo (k).

The formal relationships (1) - (6) result in:

u (k) = [vOGyro (k), s (k), t (k)] (7) x (k) = [Wl (k), pl (k), p2 (k)] (8) y ( k) = [Wl (k), wθdo (k)] (9)

In a second method step 320, the second position information of the motor vehicle 100 is determined for the predetermined times k of the time series using the second position determination system.

It should be pointed out that at a different time cycle with which the measured values are measured by the position determination systems, an interpolation of the measured values of a position determination system may have to be carried out, so that the measured values and the interpolated measured values each relate to the same times ,

If the times of the measured values differ only slightly from the position determination systems, interpolation can be omitted if necessary. However, slight inaccuracies in determining the position are accepted.

The GPS measures the following values at time k: W2 (k): orientation, wGPS (k): speed.

The second position information at a time k thus comprises the large W2 (k) and the large wGPS (k), which are combined to form a GPS position vector GPS (k) = [W2 (k), wGPS (k)]. In a third method step 330, error information is determined for all predetermined times k of the time series using the first and the second position information of the respective time in such a way that a difference between the respective first and second position information is determined.

This determines a time series for the error information.

It should be pointed out that the time series begins at the time k = 0, which is to be understood as starting up the navigation system 110 or 200.

Formal relationships of the third 330 method step are described on the basis of a better comprehensibility in a later method step.

In a fourth method step 340, a measure for a statistical dependency between the defect information is determined.

Formal correlations of the fourth 340 process step are described in a later process step because they are easier to understand.

In a fifth method step 350 and using the measure for the statistical dependency between the defect information, the improved current position information for the current position of the motor vehicle is determined.

The third 330, the fourth 340 and the fifth 350 process steps are based on formal relationships using a Kalman filter and a Kalman filter, respectively. which or which m [2] is or are realized.

It also applies that an index z identifies an estimate or prediction of the associated quantity denoted by the index z.

Furthermore, it also applies that an index T denotes a transposed size of the size identified thereby.

The measure for the statistical dependency, in this case for a temporal error statistic, is an error covariance matrix P (k).

The following formal relationships apply:

x (k + l) = f (x (k), u (k)) + Q (k) (10] y (k) = g (x (k), u (k)) + R (k) ( 111 with:

Q (...): covariance matπx for noise,

R (...): covariance matrix for noise.

The following formal relationships also apply:

xz (k + l) = f (x (k), u (k)) (12;

Pz (k + 1) = A (k) * P (k) * AT (k) + Q (k) (13;

with: f (...): non-linear system description, A (...): system matrix, A = df / dx.

The following also applies:

K (k) = Pz (k) * CT (k) * [C (k) * Pz (k) * CT (k) + exp (dT / ff) * R (k)] -l (14! x (k) = xz (k) -K (k) * [GPS (k) -g (x (k), u (k! 15 '

P (k) exp (dT / ff) * (I-K (k) * C (k)) * Pz (k) de; with: K (...) gain factor, I: unit matrix, dT / ff: factor, l ... i output matrix, C = dg / dx

1 gscal (k) * dT 0 0 1 0 (17;

0 0 1

1 0 0

(i s; 0 0 odopulse (k)

After the method steps have been carried out, the vector y (k) has the improved current overall position information, which is further used for navigation of the motor vehicle 100 using the navigation system 110.

It should be pointed out that the use of the navigation system is not limited to a motor vehicle, but that the navigation system with an appropriate adaptation also for any other mobile but also non-mobile system, for example a maritime vehicle, an airplane or a building, can be used.

It should also be pointed out that position determination systems other than those which are described in the exemplary embodiment can also be used for an overall position determination according to the method having the features according to the independent claim or one of the developments mentioned.

A use of position detection systems as in the exemplary embodiment, a gyroscope and an odometer (first A position detecting system) and a GPS (second position determination system), but that this position is the great advantage of a motor vehicle using independent great, namely the distance Stre- blocks of the force F hrzeugs and the orientation of the motor driving ^¬ zeugs, writable.

This leads to the fact that the matrices A, C, P and K, which are particularly simply structured, result when the incorrect information is ascertained. This simple structure is used in the implementation to reduce the computational effort to about a quarter by only performing the multiplications and additions that are required instead of a complete matrix calculation.

In an alternative to the exemplary embodiment, which is shown in F g. a sixth method step 460 is provided, which is carried out between the second 320 method step and the third 330 method step and with which the second position information GPS (k) is checked for reliability. The reliability is checked according to the following logic:

WGPS (k)> Sw (19)

DOP (k)> Sdop (20)

AS (k)> Ssat (21)

Tas (k)> St (22)

With:

Sw, Adop, Ssat, St: threshold values, can also be time-dependent,

DOP (...): geometry of a current satellite constellation,

AS (...): number of available satellites,

Tas (...): Time period for AS (k)> Ssat. If all four inequalities (19) - (22) are satisfied, the second position information GPS (k) is rated as reliable.

The subsequent method steps, the third 330, the fourth 340 and the fifth 350 method step are only carried out if the second position information has been assessed as reliable.

If the second position information is judged to be not reliable, the first position information is adopted as the improved current overall position in a seventh method step 470.

Furthermore, in the alternative, an initialization step 480 is provided, which is carried out before the first method step 310 and with which size of the method are initialized. The following publications have been cited in this document:

[1] Zhao Yilin: "Vehicle Location and Navigation Systems", Artech House Publishers, p.43-104, p.239-264, 1997, ISBN 0-89006-8621-5.

[2] Brammer, Siffling: "Kalman-Bucy-Filter", Oldenbourg-Verlag, Munich, pp. 75-111, 4th edition, 1994.

[3] Zhao Yilin: "Vehicle Location and Navigation Systems", Artech House Publishers, pp. 63-75, 1997, ISBN 0-89006-8621-5.

Claims

claims

1. Method for forming total position information for a system, which total position information is determined using a first position determination system and a second position determination system,

- in which first position information of the system is determined using the first position determination system for given times, - in which second position information of the system is determined using the second position determination system for the specified times,

in which error information is determined for at least some of the predetermined times using the first and second position information of the respective time, characterized in that

- A measure for a statistical dependency between the missing information is determined and the overall position information is determined using the measure for the statistical dependency.

2. The method according to claim 1, in which error information is determined for all predetermined times.

3. The method of claim 1 or 2, wherein the first and the second position information each consist of a distance traveled by the system and / or a speed of the system and / or an orientation of the system.

4. The method according to any one of claims 1 to 3, wherein the predetermined times describe a time series.

5. The method according to any one of claims 1 to 4, in which, using the measure for the statistical dependency, the first position information and / or the second position information is / will be determined for a future point in time.

6. The method as claimed in claim 5, in which, using the first and / or the second position information for the future point in time, the first and / or the second position information is corrected for one of the predetermined points in time and the total position information is thereby formed.

7. The method according to any one of claims 1 to 6, wherein the measure for the statistical dependency is determined using a Kalman filter.

8. The method according to any one of claims 1 to 7, wherein the measure for the statistical dependency is derived from a covariance matrix, which is formed using the error information.

9. The method according to any one of claims 1 to 8, in which a reliability check is carried out for the first and / or the second position information using the measure for the statistical dependency.

10. The method according to any one of claims 1 to 9, used in a navigation system with which a position of a system to be navigated is determined.

11. Arrangement for forming total position information for a system, which total position information can be determined using a first position determination system and a second position determination system, which arrangement has a processor which is set up in such a way that first position information of the system can be determined using the first position determination system for predetermined times,

second position information of the system can be determined for the predetermined times using the second position determination system,

in which error information can be determined for at least part of the predetermined times using the first and second position information of the respective time, characterized in that the processor is set up in such a way that

12. The arrangement according to claim 11, wherein the first position determination system comprises an odometer and a gyroscope.

13. Arrangement according to claim 11 or 12, wherein the second position determination system is a GPS system.

14. Arrangement according to one of claims 11 to 13, wherein the system is a motor vehicle.