A METHOD FOR ESTIMATING THE ATTITUDE OF A VEHICLE

Abstract

A method for estimating the attitude of a vehicle by using a global navigation satellite system having a plurality of satellites, wherein the vehicle comprises at least a first antenna and a second antenna having a separation to each other, comprising the steps of: detecting an outage of said global navigation satellite system; starting a dead-reckoning algorithm in order to extrapolate a change in attitude during the outage of said global navigation satellite system obtaining a dead-reckoned attitude; detecting that said global navigation satellite system has recovered, in particular via the availability of carrier phase observables and calculating a new attitude using the recovered global navigation satellite system by incorporating the obtained dead-reckoned attitude as a starting condition.

Claims

1. A method for estimating the attitude of a vehicle by using a global navigation satellite system having a plurality of satellites, wherein the vehicle comprises at least a first antenna and a second antenna having a separation to each other, characterized by the steps of: detecting an outage of said global navigation satellite system; starting a dead-reckoning algorithm in order to extrapolate a change in attitude during the outage of said global navigation satellite system obtaining a dead-reckoned attitude; detecting that said global navigation satellite system has recovered via the availability of carrier phase observables; calculating a new attitude using the recovered global navigation satellite system by incorporating the obtained dead-reckoned attitude as a starting condition.

2. A method according to claim 1, wherein the outage of said global navigation satellite system is detected via carrier-phase-measurements, in particular via the availability of carrier phase observables.

3. A method according to claim 1, wherein the dead-reckoned attitude is only provided by internal aiding, in particular such as vehicle sensor data of said vehicle.

4. A method according to claim 1, wherein the outage of said global navigation satellite system is less than 10 minutes, preferably less than 5 minutes, more preferably less than 2 minutes.

5. A method according to claim 1, wherein the change in attitude is based on said dead-reckoning algorithm and a previous known attitude.

6. A method according to claim 5, wherein the known attitude was validated before said outage of the global navigation satellite system.

7. A method according to claim 1, further comprising the step of: using said new attitude as a starting condition in a lambda-method, in particular while the global navigation satellite system is active or after said outage.

8. A method according to claim 7, wherein said lambda-method comprises the usage of at least one Kalman filter and said new attitude is used as a starting condition for said Kalman filter.

9. A computer program comprising program code means for performing the steps of claim 1 when said program is run on a computer.

10. A computer readable medium carrying a computer program comprising program code means for performing the steps of claim 1 when said program product is run on a computer.

11. An estimation unit for estimating the movement of a vehicle, the estimation unit configured to perform the steps of the method according to claim 1.

12. A movement estimation device for a vehicle, characterized in that the movement estimation device comprises a computer and at least one of: a computer program according to claim 9.

13. A vehicle comprising a movement estimation device according to claim 12.

14. A vehicle according to claim 13, further comprising at least a first antenna and a second antenna for communicating with a global navigation satellite system, in particular to provide raw satellite observables.

15. A vehicle according to claim 13, further comprising at least: one movement speed estimation unit having at least one movement speed and/or movement direction sensor and/or two global navigation satellite system receivers for tracking carrier phases.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0053] In the drawings:

[0054] FIG. 1 shows a vehicle having two antennas interacting with a global navigation satellite system in order to estimate the attitude of said vehicle,

[0055] FIG. 2 shows a vehicle having two antennas in a topview,

[0056] FIG. 3 shows an embodiment of a method according to the invention, and

[0057] FIG. 4 shows a preferred embodiment of a method according to the invention.

[0058] FIG. 5 shows an embodiment of a method according to another aspect of the invention, and

[0059] FIG. 6 shows a preferred embodiment of a method according to another aspect the invention.

[0060] Still other objects and features of embodiments herein will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits hereof, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0061] FIG. 1 shows a vehicle 1000, in particular a truck, having an attitude A and interacting with a global navigation satellite system 2000 via a first and a second antenna 1200, 1210 in order to obtain said attitude A of said vehicle 1000.

[0062] Hence, said vehicle comprises at least a first antenna 1200 and a second antenna 1210 having a separation d to each other and preferably the height h for communicating with the global navigation satellite system 2000. In a preferred embodiment, said vehicle 1000 also comprises two receivers for communicating with the global navigation satellite system 2000.

[0063] Moreover, said vehicle 1000 also comprises a movement estimation device 1100 and a movement speed estimation unit 1300.

[0064] Said movement estimation device 1100 comprises a computer program 1110, a computer readable medium 1120 and an estimation unit 1130.

[0065] Said movement estimation device 1100 is further adapted for performing said above or below described method 100 for estimating the attitude A of said vehicle 1000.

[0066] In particular, said movement estimation device 1100 is connected to said antennas 1200, 1210 and said movement speed estimation unit 1300.

[0067] Preferably, said antennas 1200, 1210 are installed at the roof of said vehicle 1000 and the movement speed estimation unit 1300 comprises a movement speed and/or movement direction sensor 1310, which is arranged for estimating the speed and/or direction of said vehicle 1000. Preferably, said vehicle 1000 also comprises a first receiver 1201 and a second receiver 1202, in particular wherein said first receiver 1201 corresponds to said first antenna 1200 and said second receiver 1211 corresponds to said second antenna 1210.

[0068] Said global navigation satellite system 2000 comprises at least a plurality of satellites 2010, 2020, 2030, 2040 and preferably a base station interacting with said antennas 1200, 1210 of said vehicle 1000, in particular via the signals S1, S1′, S2, S2′, S3, S3′, S4, S4′.

[0069] Thus, said vehicle 1000 is adapted for double difference via said antennas 1200, 1210.

[0070] One way of estimating said attitude A of said vehicle 1000 is proposed in FIG. 3 and/or FIG. 4 as well as in FIG. 5 and/or FIG. 6.

[0071] FIG. 2 shows a vehicle 1000 having two antennas 1200, 1210 in a topview, in particular the topview of said vehicle 1000 in FIG. 1.

[0072] Said vehicle 1000 has an attitude A and said antennas 1200, 1210 are mounted at the roof at said vehicle 1000, having a separation d to each other. Preferably, said antennas 1200, 1210 are installed at said roof such that said separation d is square to said attitude A.

[0073] FIG. 3 shows an embodiment of a method 100 for estimating the attitude of a vehicle, preferably a truck as shown in FIG. 1 and/or FIG. 2.

[0074] The method 100 comprises the steps of: detecting an outage 110 of the global navigation satellite system; starting a dead-reckoning algorithm 120; detecting that said global navigation satellite system has recovered 130 and calculating a new attitude 140.

[0075] In a first step 110, it is detected that said global satellite navigation satellite system has an outage, e.g. said global navigation satellite system does not provide proper carrier phase observables. Preferably, said outage is detected by an global navigation satellite system receiver which is part of said vehicle.

[0076] In a second step 120, when the outage of said global navigation satellite system is present, a dead-reckoning algorithm is started. The dead-reckoning algorithm is used to extrapolate the change in attitude (of said vehicle) during said outage of said global navigation satellite system, in particular to obtain a dead-reckoned attitude. Preferably, said dead-reckoned attitude is used as a substitute for the regular attitude, which may not be calculated due to said outage of said global navigation satellite system.

[0077] In a third step 130, it is detected that said global navigation satellite system has recovered. Preferably, by using an availability of carrier phase observables. Thus, the global navigation satellite system is defined as recovered when normal carrier phase observables, as before said outage of said global navigation satellite system, are available.

[0078] In a fourth step 140, the new attitude is calculated, in particular by using the recovered global navigation satellite system, e.g. the carrier phase observables, and said dead-reckoned attitude as a starting condition. Thus, said new attitude is based said dead-reckoned attitude and information of said recovered global navigation satellite system. By using said dead-reckoning attitude for estimating the attitude, faster convergence in search is enabled.

[0079] FIG. 4 shows a preferred embodiment of a method 100 for estimating the attitude of a vehicle, preferably a truck as shown in FIG. 1 and/or FIG. 2.

[0080] The method 100 comprises the steps of: detecting an outage 110 of the global navigation satellite system; starting a dead-reckoning algorithm 120; detecting that said global navigation satellite system has recovered 130, calculating a new attitude 140 and using said new attitude as a starting condition 150.

[0081] In a first step 110, it is detected that said global satellite navigation satellite system has an outage, e.g. said global navigation satellite system does not provide proper carrier phase observables. Thus, carrier phase observables ϕ.sub.L, in particular raw carrier phase observables, are used to determine whether the global navigation satellite system is available or not, e.g. by a global navigation satellite system receiver of said vehicle.

[0082] In a second step 120, when no suitable carrier phase observables are available, an outage of said global navigation satellite system is assumed and therefore, a dead-reckoning algorithm is started. The dead-reckoning algorithm is used to extrapolate the change in attitude (of said vehicle) during said outage of said global navigation satellite system, in particular to obtain a dead-reckoned attitude A.sub.DR. Said change in attitude is based on said dead-reckoning algorithm and a previous known attitude A.sub.KN. Said previous known attitude A.sub.KN is, for example, the last known and used attitude while said global navigation satellite system was available. Thus, said dead-reckoned attitude is used as a substitute for the regular attitude, which may not be calculated due to said outage of said global navigation satellite system.

[0083] In a third step 130, it is detected that said global navigation satellite system has recovered. Preferably, by using an availability of carrier phase observables ϕ.sub.L. Thus, the global navigation satellite system is defined as recovered when normal carrier phase observables, as before said outage of said global navigation satellite system, are available. In preferred embodiment, said outage of said global navigation satellite system is less than 5 minutes, preferably less than 2 minutes. Thus, the proposed method is addressed to short outages of said global navigation satellite system, e.g. while said vehicle is passing a tunnel.

[0084] In a fourth step 140, the new attitude is calculated, in particular by using the recovered global navigation satellite system, e.g. the carrier phase observables, and said dead-reckoned attitude as a starting condition. Thus, said new attitude is based said dead-reckoned attitude and information of said recovered global navigation satellite system. By using said dead-reckoning attitude for estimating the attitude, faster convergence in search is enabled

[0085] In a fifth step 150, said new attitude is used as a starting condition in a lambda-method, which preferably uses a Kalman filter to estimate the attitude of said vehicle. Said lambda-method may a method as shown in FIG. 5 and/or FIG. 6.

[0086] FIG. 5 shows an embodiment of a method 200 for estimating the attitude of a vehicle, preferably a truck as shown in FIG. 1 and/or FIG. 2, more preferably by using said new attitude of a method as shown in FIG. 3 and/or FIG. 4 as a starting condition.

[0087] The method 200 comprises the steps of: performing a lambda-method 210 and/or performing a lambda-method and using a Kalman filter 220.

[0088] Thus, said lambda-method 210 is used to obtain at least one relative position of said vehicle 1000. Said vehicle may a vehicle as shown in FIG. 1 and/or FIG. 2. In particular, in said lambda-method 210 said relative position is validated in order to reduce a ratio test threshold. For this, said relative position is validated by using at least one of: the separation and the height of at least two antenna and receivers.

[0089] Alternatively or additionally, a Kalman filter 220 may used. If so, a starting condition for the Kalman filter is used based on at least one previous information about the attitude. Preferably, such previous information about the attitude, is said new attitude as described for method shown in FIG. 3 and FIG. 4. Thus, a previous information about the heading may used as a starting criteria for said Kalman filter. Advantageously, said additional validation criteria reduces the ratio test threshold which will reduce the convergence time and therefore, said proposed method will be faster than known lambda-methods. In addition, said reduction of said convergence time also leads to less hardware requirements having the same performance as known lambda-methods.

[0090] FIG. 6 shows a preferred embodiment of a method 200 as shown in FIG. 5, preferably for a truck as shown in FIG. 1 and/or FIG. 2, in particular by using said new attitude of a method as shown in FIG. 3 and/or FIG. 4 as a starting condition.

[0091] The method 200 comprises the steps of: providing a new attitude 140, in particular as shown in FIG. 3 and/or FIG. 4, as a starting condition and using said new attitude as a starting condition 150.

[0092] The step of using said new attitude as a starting condition 150 also comprises both steps as shown in FIG. 5.

[0093] Thus, the proposed method comprises the steps of: providing a new attitude 140, performing a lambda-method as described herein 150 by using a Kalman filter as described herein.

REFERENCE NUMERALS

[0094] 100 method for estimating the attitude of a vehicle [0095] 110 step of: detecting an outage [0096] 120 step of: starting a dead-reckoning algorithm [0097] 130 step of: detecting recovery [0098] 140 step of: calculating a new attitude [0099] 150 step of: using said new attitude as a starting condition [0100] 200 method for estimating the attitude of a vehicle [0101] 210 step of: performing a lambda-method [0102] 220 step of: using a Kalman filter [0103] 1000 vehicle [0104] 1100 movement estimation device [0105] 1110 computer program [0106] 1120 computer readable medium [0107] 1130 estimation unit [0108] 1200 first antenna [0109] 1201 first receiver [0110] 1210 second antenna [0111] 1211 second receiver [0112] 1300 movement speed estimation unit [0113] 1310 movement speed sensor [0114] 2000 global navigation satellite system [0115] 2010, 2020, 2030 2040 plurality of satellites [0116] A attitude of said vehicle [0117] A.sub.DR dead-reckoned attitude of said vehicle [0118] A.sub.KN known attitude of said vehicle [0119] d distance between antennas [0120] h height of antennas [0121] KF Kalman filter [0122] S1, S2, S3, S4 first signals of said satellites [0123] S1′, S2′, S3′, S4′ second signals of said satellites [0124] ϕ.sub.L observable [0125] λ lambda-method