Devices for determining the attitude of a vehicle, related systems for assisting in driving the vehicle, and methods for determining the attitude.

Abstract

The present invention relates to an apparatus (16) for determining the attitude of a vehicle, the vehicle including a GNSS receiver capable of receiving GNSS signals from one or more antennas (14) arranged at a known location; the determining apparatus (16) includes: a motion generation module (22) configured to generate a motion of the apparent phase center according to a control law; a control module (23) configured to determine the control law; and a determining module (24) configured to determine the absolute orientation of a vector of interest based on at least one observable provided by the GNSS receiver (12) and according to the control law, and to determine at least one component of the attitude of the vehicle based on the absolute orientation of the vector of interest.

Description

Technical Field

[0001] This invention relates to an apparatus for determining the attitude of a vehicle.

[0002] The present invention also relates to a system for assisting the driving of a vehicle in association with a determining device and a method for determining the attitude of a vehicle.

[0003] The field of this invention is the field of GNSS receivers.

[0004] More specifically, a GNSS receiver is a receiver used to receive GNSS signals (i.e., signals from one or more global navigation satellite systems) and to determine a navigation solution, including position and velocity, based on these signals.

[0005] The present invention is applied in the field of controlling the driving of a vehicle, and particularly in the field of controlling the attitude of such a vehicle. The attitude of a vehicle includes its heading, roll, and pitch, in a manner known per se. Background Technology

[0006] In the existing technology, there are already many devices for determining the attitude of a vehicle.

[0007] In these devices, a method for determining attitude using a GNSS receiver is known, according to which the receiver analyzes GNSS signals received by a set of antennas in order to measure the phase difference of the vehicle and thereby infer the orientation of the antenna base.

[0008] However, this approach uses a specially designed GNSS receiver, which is typically more complex and less common than a GNSS receiver that only provides positioning services. This specially designed receiver needs to interact with multiple antennas either through parallel processing of the antenna signals or through sequential processing of the antenna signals. In the second solution, the receiver sequentially connects its RF input to each antenna via a fast electronic switch and analyzes segments of the received signal to measure the carrier phase difference between the antennas. Summary of the Invention

[0009] The object of this invention is to provide a device for determining the attitude of a vehicle, which works in conjunction with a GNSS receiver that provides positioning services independently.

[0010] Therefore, the object of the present invention is an apparatus for determining the attitude of a vehicle, the vehicle including a GNSS receiver for receiving GNSS signals from one or more antennas arranged at a known position relative to the vehicle and defining an apparent phase center, the GNSS receiver readily providing observables determined based on the received GNSS signals.

[0011] The determining device includes: a motion generation module configured to generate a motion of the apparent phase center according to a predetermined control law; a control module configured to determine the control law; and a determining module configured to determine the absolute orientation of the vector of interest based on at least one observable provided by the GNSS receiver and the control law determined by the control module, and the determining module is further configured to determine at least one of the observables as a component of the vehicle attitude based on the determined absolute orientation of the vector of interest.

[0012] According to other advantageous aspects of the invention, the determining device includes one or more of the following features, which may be present individually or in all technically possible combinations:

[0013] The vector of interest is obtained by measuring the amplitude of the modulation of the observable, the modulation of the observable being caused by periodically setting the shift of the apparent phase center;

[0014] The observable values ​​include at least one, preferably two, and advantageously three, geovelocity coordinates provided by the GNSS receiver;

[0015] When the vehicle includes at least two antennas, the motion generation module is a switch that switches the signals received by each antenna to the transmission of the GNSS receiver in order to generate the electrical motion of the apparent phase center according to the control law.

[0016] When the vehicle includes two switching antennas, the control law is a square wave signal;

[0017] The motion generation module is used to control at least one mechanical actuator of the vehicle and / or each antenna to generate mechanical movement of the apparent phase center according to the control law;

[0018] The components of the attitude of the vehicle correspond to the heading angle, roll angle, or pitch angle of the vehicle.

[0019] When it is necessary to determine the heading angle and the pitch angle, the control law limits the displacement of the apparent phase center along the longitudinal axis of the vehicle;

[0020] When it is necessary to determine the roll angle, the control law limits the displacement of the apparent phase center along the lateral axis of the vehicle;

[0021] The vector of interest corresponds to the absolute direction of the displacement at the apparent phase center;

[0022] When the observable value is a measurement of the resolved velocity of the vehicle, the vector of interest is determined according to the following relationship:

[0023] δV=b(t).(d X ,d Y ,d Z ) T

[0024] in,

[0025] δV is the analytical velocity deviation vector;

[0026] b(t) is a function that depends on the control law;

[0027] (d X ,d Y ,d Z ) T It is the vector of interest.

[0028] Another subject of the present invention is a system for assisting the driving of a vehicle, the system comprising:

[0029] GNSS receivers are used to provide observables;

[0030] One or more antennas are arranged at a known location relative to the vehicle and define an apparent phase center;

[0031] The apparatus described above for determining the attitude of a vehicle.

[0032] Another subject of the invention is a method for determining the attitude of a vehicle, the vehicle including a GNSS receiver for receiving GNSS signals from one or more antennas arranged at a known position relative to the vehicle and defining an apparent phase center, the GNSS receiver for providing observables determined based on the received GNSS signals;

[0033] The method includes:

[0034] Determine the control law for the apparent phase center;

[0035] The movement of the apparent phase center is set according to the control law;

[0036] The absolute orientation of the vector of interest is determined based on at least one observable provided by the GNSS receiver and according to the control law.

[0037] At least one component of the vehicle's attitude is determined based on the absolute orientation of the determined vector of interest. Attached Figure Description

[0038] The features and advantages of the present invention will become apparent upon reading the following description, which is given by way of example but is not limited thereto, and with reference to the accompanying drawings, in which:

[0039] Figure 1 This is a schematic diagram of a system for assisting the driving of a vehicle according to the present invention. In the example shown in the diagram, the system specifically includes two antennas and a determining device according to the present invention.

[0040] Figure 2 yes Figure 1 A schematic diagram showing the arrangement of the antennas;

[0041] Figure 3 yes Figure 1 A flowchart of the determination method used by the determination device shown;

[0042] Figure 4 This is an explanation Figure 1 A schematic diagram showing the function of the determining device. Detailed Implementation

[0043] Figure 1 The system 10 for assisting driving shown is used to geolocate the vehicle, wherein the system is on the vehicle and is used to determine the vehicle's attitude. Such information can be used, for example, by the driver to drive the vehicle at least partially manually and / or via avionics systems, so as to at least partially automate the vehicle.

[0044] Vehicles include, for example, aircraft that move in three-dimensional space, such as unmanned aerial vehicles, or land or sea vehicles that move in a two-dimensional plane, or railway vehicles that move in one direction along railway tracks.

[0045] The vehicle defines a coordinate system associated with its body, the orientation of which is relative to a fixed coordinate system (e.g., a ground coordinate system), and then defines the vehicle's attitude. This orientation can be described using three angles known in the art as heading, roll, and pitch.

[0046] The vehicle also defines a longitudinal axis as well as a transverse axis and a normal axis perpendicular to the longitudinal axis, about which rotation that generates the roll angle is defined.

[0047] The system 10 for assisting driving includes a GNSS receiver 12, one or more antennas 14, and a determining device 16.

[0048] The one antenna 14 or each of the plurality of antennas 14 is known in itself and specifically used to receive GNSS signals from one or more global positioning systems, such as GPS, Galileo, or GLONASS.

[0049] More specifically, as is known per se, each of the one or more antennas 14 defines a phase center and is placed at a known location relative to the vehicle.

[0050] Therefore, in the coordinate system of the vehicle, the position of the one antenna 14 or each of the plurality of antennas 14 is known at all times. Specifically, this means that the position of the phase center of the one antenna 14 or each of the plurality of antennas 14 is also known in the same coordinate system.

[0051] The number of antennas 14 is selected according to the embodiments described in detail below.

[0052] More specifically, according to the first embodiment (not shown in the figure), only one antenna 14 is used. In the coordinate system of the vehicle, the antenna 14 can be movable or fixed. When the antenna 14 is movable, it is mounted, for example, on an actuator provided for this purpose.

[0053] According to an example of this embodiment, the term "apparent phase center" as used below refers to the phase center of antenna 14.

[0054] According to the second embodiment (as shown in the figure), a plurality of antennas 14 are used. Each of the antennas 14 has an antenna that is fixed, for example, in the coordinate system of the vehicle.

[0055] According to an example of this embodiment, the term "apparent phase center" refers to the phase center of antenna 14 that is active at a given time; or it refers to the phase center obtained after superimposing the phase centers of the active antenna 14 when multiple antennas are active at the same time and signals from these antennas are superimposed.

[0056] exist Figure 1 In the example shown, two antennas 14 are illustrated.

[0057] exist Figure 2 The positions of the respective antennas 14 are shown in more detail below.

[0058] More specifically, in Figure 2 In the example shown, the antenna 14 is placed in the same plane P.

[0059] Furthermore, the antennas 14 are spaced apart from each other by half the wavelength of the GNSS signal.

[0060] This means that the antennas 14 are about 10 centimeters apart.

[0061] The antennas 14 can be moved away from each other by another distance. Preferably, this other distance is less than one wavelength of the GNSS signal.

[0062] The distance between a pair of antennas 14 will be denoted by d below. Figure 2 In the example, d = λ / 2.

[0063] Typically, in embodiments using multiple antennas, the relative positions of the antennas with respect to each other and with respect to the vehicle are known.

[0064] Therefore, it can be understood that, in one embodiment, the trajectory of the phase center in the reference frame of the vehicle is obtained by applying mechanical displacement of only one antenna along a controlled path, and in another embodiment, the mechanical displacement of only one antenna is obtained by continuously switching multiple antennas according to a controlled sequence and duty cycle, the positions of the multiple antennas being known in the reference frame of the vehicle.

[0065] GNSS receiver 12 is known in itself. It is a positioning service that provides measurements of a vehicle's position in a geographic coordinate system in three coordinates, and measurements of the vehicle's velocity in a geographic coordinate system, by observing signals received from only one antenna. It can also provide pseudo-range and pseudo-velocity measurements for each tracked satellite. These different types of measurements are then referred to as observables.

[0066] In a known manner, specifically by filtering the signal received from the antenna, and by performing correlation processing and other types of processing on the signal, the observable is determined.

[0067] More specifically, when the antenna is associated with the motion generating device, the receiver 12 is connected to only one antenna 14, or when multiple antennas are present, the receiver 12 is connected to a module 22 with multiple antennas 14 (explained in detail below), such as Figure 1 As shown.

[0068] The determining device 16 is used to determine the vehicle's attitude by specifically analyzing observables from the GNSS receiver 12. The vehicle's attitude is determined under the assumption that the GNSS signal propagates along a direct path. In other words, the attitude is determined under the assumption that multipath (i.e., spurious signals due to specular reflection of satellite signals) is substantially absent or negligible. This is particularly true when the vehicle is above a certain altitude or moving in an open environment, such as outside of an urban environment.

[0069] Reference Figure 1 The determining device 16 includes a movement generation module 22, a control module 23, and a determining module 24.

[0070] Each of modules 23 and 24 may take the form of software implemented by a suitable computer and / or at least in part as a hardware component, such as a programmable logic circuit of the FPGA (for “Field Programmable Gate Array”) type.

[0071] The motion generation module 22 is used to generate the motion of the apparent phase center of the antenna 14 according to a predetermined control law.

[0072] The motion generation module 22 can also be used to receive signals received by one antenna or each of the plurality of antennas, so as to transmit the received signals to the receiver 12. Furthermore, in the case of multiple antennas, the module 22 is used to combine the signals before transmitting the received signals to the receiver 12.

[0073] According to the first embodiment, when the system 10 includes only one antenna 14, the movement generated by the module 22 is mechanical.

[0074] In other words, in this case, when the antenna is movable, the motion generation module 22 is used to control the mechanical actuator on which the antenna 14 is mounted, or when the antenna is fixed, the motion generation module 22 is used to control at least one actuator of the vehicle itself for moving the vehicle. In a variant, when the antenna is movable, the motion generation module 22 is used to simultaneously control the actuator of the antenna and at least one actuator of the vehicle.

[0075] According to a second example of the embodiment, when the system 10 includes at least two antennas 14, the motion generation module 22 can easily generate the apparent phase center movement of the antennas 14 electrically.

[0076] In other words, in this case, the physical location of antenna 14 does not change, but the transmission of GNSS signals received by the antenna is switched according to the control law.

[0077] In this case, the motion generation module 22 can take the form of an electronic radio frequency multiplexer with "N inputs to one output", where N is the number of antennas, and the single output is connected to an antenna assigned by control applied to the multiplexer.

[0078] The control module 23 can be used to determine the control law. This law is determined based on the desired shift of the apparent phase center of one or more antennas 14.

[0079] More specifically, if the heading and pitch angles are of interest, the apparent phase center should be moved along the longitudinal axis of the vehicle.

[0080] If the roll angle is of interest, it should be moved along the lateral axis of the vehicle.

[0081] If you are interested in these three angles, you will have to move along the longitudinal and transverse axes.

[0082] When the movement of the phase center is electrically generated, two antennas 14 are sufficient to determine at least two components of the vehicle's attitude, such as heading and pitch, and three antennas 14 are sufficient to determine each component of the vehicle's attitude.

[0083] Furthermore, the control law is selected based on the nature of the movement generated by the movement generation module 22.

[0084] For example, when movement is acquired through electronic switching of two antennas, the control law provides, for instance, a scalar signal at a frequency of a few Hz in a pseudo-random manner. This scalar signal takes two values—selecting the first antenna and selecting the second antenna. The switching frequency is chosen to be fast enough relative to the passband of the desired attitude change to be observed, but slow enough relative to the passband of the receiver's tracking loop. The choice of the switching duty cycle (a fixed duty cycle sequence or a pseudo-random sequence) can be used to decouple natural movement from the observable, and to decouple controlled movement from the observable. The observable contains the effects of both types of movement: for example, if the observable is a geographic velocity vector, this vector carries the velocity change caused by the vehicle's trajectory and the velocity change caused by the switched antennas, where only the second component (i.e., the velocity change caused by the switched antennas) carries the attitude information that is desired.

[0085] Furthermore, depending on the characteristics of the apparent movement of the antenna and the nature of the GNSS signal used, the presence of such movement may impair certain receiver functions, such as demodulation of data transmitted on certain components of the GNSS signal, or operation at low signal-to-noise ratios. Therefore, it is advantageous to stop antenna movement during certain phases of the mission, or to activate the antenna briefly.

[0086] Therefore, the parameters of the control law c(t), namely, the movement with one or two degrees of freedom, the repetition frequency of the movement, the variable regular sequence, continuous operation or segmented operation, set the service provided, the performance of the service and the complexity of device 16, provide two or three attitude angles, tolerance to variable dynamics of vehicle attitude changes, tolerance to variable dynamics of vehicle trajectory, and the service provided continuously or during certain phases of the mission. These parameters are also selected based on certain characteristics of the GNSS receiver used, such as the bandwidth of its GNSS signal tracking loop, and can vary significantly between different manufacturers.

[0087] Generally speaking, the chosen control law c(t) can separate the change in geographic velocity caused by the trajectory of the vehicle from the change caused by the movement of the apparent phase center.

[0088] According to a specific example of the invention, the control law c(t) is a square wave signal, for example, in the case of two antennas, which alternately activates and deactivates each antenna according to a predetermined frequency.

[0089] The determination module 24 is configured to determine the orientation of the vehicle based on observables determined by the GNSS receiver 12 and control laws determined by the control module 23.

[0090] Subsequently, refer to the flowchart illustrating the method. Figure 3 and the function of the explanatory device 16 Figure 4 This explains the determination performed by the determining device 16 according to the invention. As described above, advantageously, this method is implemented under the assumption that the GNSS signal propagates along a direct path.

[0091] During the initial step 110, the control module 23 determines the control law c(t).

[0092] As described above, the control law c(t) is determined based on the expected movement at the apparent phase center and the properties of the movement generation module 22.

[0093] Step 110 is implemented, for example, before using system 10 in a vehicle.

[0094] When the GNSS receiver 12 is operational and determines the observables and the location PT of the vehicle, the following steps are performed.

[0095] More specifically, during step 120, the movement generation module 22 sets the movement of the apparent phase center c(t) according to the control law determined by the control module 23.

[0096] During the next step 130, the determination module 24 acquires observables from the GNSS receiver 12, which are then varied specifically according to the control law c(t).

[0097] To simplify the following description, the observable value will be assumed to be the velocity resolved by GNSS receiver 12.

[0098] For the sake of simplicity, the analysis of the heading and pitch angles will be considered the focus of this discussion. Obtaining these two angles is equivalent to obtaining the unit vector carried along the longitudinal axis of the vehicle.

[0099] For simplicity, the movement of the controlled phase center will be assumed below to be achieved by switching two antennas separated by a known distance *d* and positioned along the longitudinal axis of the vehicle. Therefore, it will be understood that the analytical heading and pitch angles are equivalent to obtaining the vectors of the two separated antennas. (Hereinafter referred to as the vector of interest) has three coordinates in the geographic coordinate system. In the case of only one movable antenna, the vector... The displacement vector corresponding to the apparent phase center then moves along the longitudinal axis of the vehicle (when yaw and pitch angles are required) or along the lateral axis of the vehicle (when roll angles are required).

[0100] During the next step 140, module 24 determines the vector in the manner discussed in detail below.

[0101] The speed, and the speed in the fourth line which includes the value DH (which represents the clock drift of GNSS receiver 12 relative to the clock of the GNSS system under consideration), are as follows:

[0102]

[0103]

[0104] It is known that GNSS receiver 12 typically uses N pseudo-velocity measurements (here, PRR1, PRR2, ..., PRR) obtained for each tracked GNSS satellite. N The least squares calculation of vector V is used to calculate the vector V. + .

[0105] Let H denote the observation matrix of dimension N×4, containing the view vector in the k-th row. The three coordinates and "1" are given, and Z represents the vector formed by N pseudo-velocity measurements:

[0106]

[0107] How to derive vector V from a small change in the descriptor vector Z (denoted as δZ)? + Small changes (denoted as δV) +The specific relationship is as follows:

[0108]

[0109] More specifically, the axis vector associated with the k-th satellite It is a unit vector containing the three coordinates of the segment that connects the launch vehicle to the satellite.

[0110] It is also known that the path difference, expressed in meters, between the path followed by the signal transmitted by the k-th satellite and received by the first antenna and the path followed by the signal transmitted by the k-th satellite and received by the second antenna at the same time is written as a vector. With vector scalar product between

[0111]

[0112] If the control law c(t) switches the two antennas with a period T (in seconds), and the receiver's tracking loop recovers the dominant frequency component of the movement, it causes a quasi-sinusoidal change in the pseudo-velocity measured by the receiver, which has the following form:

[0113]

[0114] Expressed in meters per second

[0115] The quantity 2 / π is the amplitude of the main sinusoidal component in the harmonic components of a unit amplitude square wave periodic signal.

[0116] More generally, b(t) represents a function of the modulated pseudo-velocity measurement:

[0117] δPRR k =b(t).ddm k Expressed in meters per second

[0118] The function b(t) depends on the control law c(t) and the passband of the signal tracking loop inside the receiver: if the phase center moves too quickly, the receiver's passband will tend to excessively reduce the amplitude of the effect caused by pseudo-velocity control. This is not the desired effect of the device.

[0119] By applying the above relation in relation 1, and considering that the control law c(t) has the same effect on all tracked satellites, we can obtain:

[0120]

[0121] use Represents vector Adding the fourth row to 0 changes the above relationship to:

[0122]

[0123] Then,

[0124]

[0125] Then,

[0126]

[0127] Finally, only the first 3 rows of the vector are retained:

[0128]

[0129] Therefore, it can be understood that the observable value, namely the geographic velocity generated by receiver 12 in the above example, changes by applying a control law, and the amount of change... The vector of interest is modulated by the signal b(t). The signal b(t) is defined by the control signal c(t) and the known passband of the receiver 12.

[0130] Then, during step 140, the vector of interest is obtained by eliminating the modulation function b(t) in the above relationship. In the example, the command c(t) is a square wave signal, and the function b(t) is a pseudo-sine wave signal with the same frequency as c(t). To access the vector... The work of step 140 includes measuring the amplitude of the sinusoidal component on the three coordinates of the velocity, the frequency of which is known.

[0131] Once you are interested in vectors Given the three coordinates, step 150 derives the heading angle C and pitch angle T in a known manner (e.g., considering the north, east, and vertical coordinates):

[0132]

[0133]

[0134] At the end of step 150, the determining module 24 sends one or more of the determined components to, for example, another avionics system and / or displays them to the pilot. Steps 130 to 150 can then be repeated to update the vehicle's attitude.

[0135] Thus, it can be understood that the present invention has a number of advantages.

[0136] More specifically, this invention can be used to determine the attitude of a vehicle by using a GNSS receiver that only provides positioning services and setting the movement of the phase center according to known rules. Unlike GNSS receivers specifically designed to provide attitude determination services from multiple antennas, receivers equipped only with positioning services and thus managing only one antenna are widely used in many application areas.

Claims

1. An apparatus (16) for determining the attitude of a vehicle, the vehicle including a GNSS receiver for receiving GNSS signals from one or more antennas (14) arranged at a known position relative to the vehicle and defining an apparent phase center, the GNSS receiver (12) for providing observables determined based on the received GNSS signals; The device (16) for determining the attitude of the vehicle includes: A motion generation module (22) is configured to generate a motion of the apparent phase center according to a predetermined control law; Control module (23), configured to determine the control law; and The determination module (24) is configured to determine the absolute orientation of the vector of interest based on at least one observable provided by the GNSS receiver (12) and a control law determined by the control module (23); The determining module (24) is also configured to determine at least one component of the vehicle's attitude based on the absolute orientation of the determined vector of interest.

2. The apparatus (16) for determining the attitude of a vehicle according to claim 1, wherein, The vector of interest is obtained by measuring the amplitude of the modulation of the observable, the modulation of which is caused by periodically setting the shift of the apparent phase center.

3. The apparatus (16) for determining the attitude of a vehicle according to claim 1, wherein, The observable values ​​include at least one of the geographic velocity coordinates provided by the GNSS receiver (12).

4. The apparatus (16) for determining the attitude of a vehicle according to claim 1, wherein, When the vehicle includes at least two antennas (14), the motion generation module (22) is a switch for switching the transmission of signals received by the antennas (14) to the GNSS receiver (12) to generate the electrical motion of the apparent phase center according to the control law.

5. The apparatus (16) for determining the attitude of a vehicle according to claim 4, wherein, When the vehicle includes two switching antennas (14), the control law is a square wave signal.

6. The apparatus (16) for determining the attitude of a vehicle according to claim 1, wherein, The motion generation module (22) is capable of controlling at least one mechanical actuator of the vehicle and / or one antenna (14) or each of the plurality of antennas (14) to generate the mechanical movement of the apparent phase center in accordance with the control law.

7. The apparatus (16) for determining the attitude of a vehicle according to claim 1, wherein, The attitude components of the vehicle correspond to the heading angle, roll angle, or pitch angle of the vehicle.

8. The apparatus (16) for determining the attitude of a vehicle according to claim 7, wherein, When it is necessary to determine the heading angle and the pitch angle, the control law limits the displacement of the apparent phase center along the longitudinal axis of the vehicle.

9. The apparatus (16) for determining the attitude of a vehicle according to claim 7, wherein, When it is necessary to determine the roll angle, the control law limits the displacement of the apparent phase center along the lateral axis of the vehicle.

10. The apparatus (16) for determining the attitude of a vehicle according to claim 1, wherein, The vector of interest corresponds to the absolute direction of the displacement at the apparent phase center.

11. The apparatus (16) for determining the attitude of a vehicle according to claim 1, wherein, When the observable value is a measurement of the resolved velocity of the vehicle, the vector of interest is determined according to the following relationship: in, It is the analytical velocity deviation vector; It is a function that depends on the control law; It is the vector of interest.

12. A system (10) for assisting in driving a vehicle, the system (10) comprising: GNSS receiver (12), which is used to provide observables; One or more antennas (14) are arranged at a known position relative to the vehicle and define an apparent phase center; A device (16) for determining the attitude of a vehicle according to any one of the preceding claims.

13. A method for determining the attitude of a vehicle, the vehicle including a GNSS receiver for receiving GNSS signals from one or more antennas (14) arranged at a known position relative to the vehicle and defining an apparent phase center, the GNSS receiver (12) for providing observables determined based on the received GNSS signals; The method includes: Determine the control law for the apparent phase center as described in (110); The movement (120) of the apparent phase center is set according to the control law. The absolute orientation of the vector of interest is determined (140) based on at least one observable provided by the GNSS receiver and according to the control law; (150) Determine at least one component of the attitude of the vehicle based on the absolute orientation of the determined vector of interest.

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