Method For Determining The Position Of A Vehicle As A Function Of The Vehicle Velocity

Abstract

A method for determining the position of a vehicle is disclosed. GNSS signals from a global satellite navigation system are received by a receiving device). A vehicle velocity is detected; and a check is carried out as to whether the detected vehicle velocity falls below or exceeds a threshold value. After the vehicle velocity falls below the threshold value, the position of the vehicle is determined on the basis of a first calculation method. After the vehicle velocity exceeds the threshold value, the position of the vehicle is determined on the basis of a second calculation method. Both calculation methods include filtering the GNSS signals by a fusion algorithm. The calculation methods differing by input variables of the fusion algorithm.

Claims

1. A method for determining a position of a vehicle, the method comprises: receiving, at a receiving device, global satellite navigation system (GNSS) signals from a GNSS; detecting a vehicle velocity; checking when the detected vehicle velocity falls below or exceeds a threshold value; when the vehicle velocity falls below the threshold value, determining the position of the vehicle by way of a first calculation method; and when the vehicle velocity exceeds the threshold value, determining the position of the vehicle by way a second calculation method, wherein both calculation methods comprise filtering the GNSS signals by a fusion algorithm, the calculation methods differing by input variables of the fusion algorithm.

2. The method according to claim 1, wherein the input variables of the fusion algorithm according to the first calculation method comprise, in contrast to the input variables of the fusion algorithm according to the second calculation method, an absolute position of the vehicle deduced from the GNSS signals.

3. The method according to claim 2, wherein the absolute position is determined on the basis of the GNSS signals and on the basis of additional signals for specifying the GNSS signals, wherein the additional signals are received by a station external to the vehicle.

4. The method according to claim 3, wherein the additional signals comprise satellite orbit and clock data from the global satellite navigation system, wherein the first calculation method is configured as a Precise Point Positioning method, or the additional signals comprise correcting information regarding the signal propagation time of the GNSS signal, wherein the first calculation method is configured as a Real Time Kinematic or Differential Global Positioning method, in which correcting information originating from at least one earth-fixed reference station which is configured to receive GNSS signals is received.

5. The method according claim 1, wherein the input variables of the fusion algorithm according to the second calculation method comprise a velocity of the vehicle deduced from the GNSS signals.

6. The method according to claim 5, wherein the velocity is deduced by an alteration in the position over time and/or from a Doppler shift of the GNSS signals.

7. The method according to claim 1, wherein dynamic information, including rotation rates and/or acceleration data of an inertial measurement unit and/or odometry information of wheel speed sensors and/or steering wheel angle information and/or information of environment sensors, is enlisted according to the second calculation method in order to determine the position of the vehicle, wherein said information is preferably not enlisted according to the first calculation method.

8. The method according to claim 1, wherein, if the vehicle velocity does not fall below the threshold value for a specific period of time, the position of the vehicle is additionally determined on the basis of the first calculation method, in which the thus determined position is then weighted more strongly in the fusion algorithm than the position established according to the second calculation method.

9. The method according to claim 1, wherein an integrity check of the position deduced from the GNSS signals is carried out, by a Receiver Autonomous Integrity Monitor.

10. A control apparatus which is designed to carry out the method of claim 1.

Description

DESCRIPTION OF DRAWINGS

[0025] FIG. 1 shows, in a schematic representation, an exemplary flow chart according to a method for determining a position of a vehicle.

[0026] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0027] A GNSS signal 11 output by a satellite 1 of a global satellite navigation system transmits, on the one hand, the time of day and orbit data (ephemerides) of the satellite 1, on the other hand it allows, on the basis of the signal propagation time or respectively also the signal phase, the position of the receiving device to be established. The receiving device 2 in the form of a GNSS antenna is arranged in or on a vehicle, the position 7 of which is to ultimately be determined.

[0028] The position 7 of the vehicle is determined in that multiple input variables are supplied to a filter 4, such as, but not limited to a Kalman filter, which generates values that may be utilized with a fusion algorithm by weighting from the noisy input variables.

[0029] In addition, the vehicle has velocity detector 3 which calculates the vehicle velocity 31 based on wheel speeds with a known wheel diameter. However, any other type of velocity measurement may alternatively also be affected, for example including solely from the GNSS signals and/or IMU data. The detected vehicle velocity 31 serves as a decision-making basis for which calculation method 41, 42 is subsequently used in order to determine the position 7 of the vehicle. To this end, a specific threshold value of the vehicle velocity 31 is used. This can be set at a low vehicle velocity 31 which can, for example, also virtually assume the value zero.

[0030] The calculation methods 41, 42 are distinguished, first and foremost, by which variables are used as input variables for the fusion algorithm. As long as the vehicle velocity 31 does not fall below its threshold value, a first calculation method 41 is used, in which the position 7 is determined very precisely from the GNSS signals 11. This is possible, on the one hand, because the vehicle has a low vehicle velocity 31, on the other hand because additional signals 51 from a station 5 external to the vehicle are used. In this example, the station 5 is a stationary reference station of a DGPS system so that the propagation time differences of the GNSS signals 11 can be corrected with the aid of the additional signals 51. The precisely determined position data are supplied to the fusion algorithm as input variables. The fusion algorithm can, while the first calculation method 41 is selected, carry out an adaption of some internal condition variables in order to better be able to update these during a change in the calculation method 41, 42, without a settling time occurring.

[0031] In contrast thereto, if the threshold value of the vehicle velocity 31 is exceeded, a second calculation method 42 is used, in which the position is not determined by the GNSS signals 11, but the velocity of the vehicle is determined with a method which is more robust to external influences. To this end, the Doppler shift of the received GNSS signal 11, for example, can be used, which is a function of the vehicle velocity. The thus established velocity is supplied to the fusion algorithm as an input variable.

[0032] In order to make the position 7 of the vehicle determined by the fusion algorithm more precise in accordance with the second calculation method 42, dynamic information 61 is moreover supplied to the fusion algorithm by a sensor system 6 of the vehicle. The dynamic information 61 is obtained, for example, in the form of rotation rates and accelerations by an inertial measurement unit of the vehicle or in the form of odometry data by speed and steering angle sensors. Consequently, the fusion algorithm is not supplied with all of the available variables at any time, but specific variables are deliberately selected depending on the movement condition of the vehicle, and the fusion algorithm is adapted accordingly.

[0033] The first and the second calculation method 41, 42 may alternatively also be used simultaneously, wherein the more favorable method for the respective movement condition is, however, highlighted by means of an arithmetical weighting.

[0034] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.