1. A vehicle attitude calculation method based on a satellite positioning system is characterized by comprising the following steps:

calibrating when the vehicle leaves a factory to obtain fixed coordinates of the three satellite positioning modules in a finished vehicle attitude coordinate system, comparing the fixed coordinates with coordinates in a satellite positioning system, and establishing an initial conversion relation between the finished vehicle attitude coordinate system and a geocentric coordinate system as an initial attitude of the vehicle; the three satellite positioning modules are arranged at different positions of the vehicle;

in the using process of the vehicle, the coordinates of the satellite positioning systems of the three satellite positioning modules at different moments are obtained and compared with the fixed coordinates in the attitude coordinate system of the whole vehicle to obtain the real-time conversion relation between the attitude coordinate system of the whole vehicle and the geocentric coordinate system, and the difference value between the real-time conversion relation and the initial conversion relation is the change of the real-time attitude of the vehicle compared with the initial attitude.

2. The satellite positioning system-based vehicle attitude calculation method according to claim 1, wherein a plurality of analysis units are arranged on the vehicle and assigned with different weights, each analysis unit including at least three satellite positioning modules and one calculation and analysis module.

3. The satellite positioning system based vehicle attitude calculation method of claim 2, wherein one of the analysis units is masked if the certain satellite positioning module is damaged.

4. The satellite positioning system-based vehicle attitude calculation method according to claim 1, wherein the transformation of the coordinate system is performed specifically by a quaternion method or a rotational matrix method.

5. The vehicle attitude calculation method based on the satellite positioning system according to claim 4, wherein when the coordinate system is converted by the rotation matrix method, the coordinate of the three satellite positioning modules in the vehicle attitude coordinate system and the coordinate in the geocentric coordinate system are used for establishing the conversion relationship between the two coordinate systems by the rotation matrix method, so as to obtain the rotation angle converted from the vehicle attitude coordinate system to the geocentric coordinate system in the initial state and the real-time state, the rotation angles in the two directions around the X axis and the Y axis are subtracted to obtain the pitch angle and the roll angle, and the time derivation is performed on the rotation angle around the Z axis to obtain the angular velocity.

6. A satellite positioning system based vehicle attitude calculation system comprising at least one analysis unit comprising:

at least three satellite positioning modules arranged at different positions of the vehicle;

a calculation and analysis module, connected to the satellite positioning module, for calculating the vehicle attitude, in particular for: obtaining fixed coordinates of the three satellite positioning modules in a finished automobile attitude coordinate system through calibration when the automobile leaves a factory, comparing the fixed coordinates with coordinates in a satellite positioning system, and establishing an initial conversion relation between the finished automobile attitude coordinate system and a geocentric coordinate system to be used as an initial attitude of the automobile;

in the using process of the vehicle, the coordinates of the satellite positioning systems of the three satellite positioning modules at different moments are obtained and compared with the fixed coordinates in the attitude coordinate system of the whole vehicle to obtain the real-time conversion relation between the attitude coordinate system of the whole vehicle and the geocentric coordinate system, and the difference value between the real-time conversion relation and the initial conversion relation is the change of the real-time attitude of the vehicle compared with the initial attitude.

7. The satellite positioning system based vehicle attitude calculation system of claim 6, wherein a plurality of analysis units are disposed on the vehicle and are given different weights.

8. The satellite positioning system based vehicle attitude calculation system of claim 7, wherein one of the analysis units is masked if the satellite positioning module is damaged.

9. The system of claim 6, wherein the calculation and analysis module performs the transformation of the coordinate system by a quaternion method or a rotational matrix method.

10. The satellite positioning system based vehicle attitude calculation system of claim 6, wherein the satellite positioning module is disposed within a passenger compartment of the vehicle.

Background

The vehicle attitude mainly refers to a vehicle pitch angle, a vehicle roll angle and a vehicle steering angular speed. Vehicle attitude monitoring is an essential component in the entire vehicle. The accuracy of vehicle attitude measurement calculation has important influence on the performance of driving safety, chassis control, automatic driving control and the like. Generally, a vehicle measures linear acceleration and angular acceleration of the vehicle around X, Y, Z three axial directions through sensors such as a triaxial acceleration sensor, a triaxial gyroscope, a magnetic sensor and the like, then performs integral calculation to obtain speed, and then performs multiple calculations to obtain information such as a pitch angle, a roll angle, a steering angle and the like of the vehicle, wherein the process is complex and has accumulated calculation errors. The triaxial acceleration sensor has high requirements on temperature, vibration and the like, so that the constraint on the arrangement position is large. Although the correction is also performed by introducing a satellite positioning system in recent years, the correction is required by an acceleration sensor, a gyroscope, or the like. Meanwhile, with the improvement of the safety requirements of the automatic driving on the vehicle functions, a set of independent system capable of providing vehicle posture information is required to be arranged on the vehicle as a safety backup.

In the prior art, acceleration and vectors in a given direction are generally obtained through a triaxial acceleration sensor, rotation angular velocities in all directions are obtained through a triaxial gyroscope, and a vehicle pitch angle, a vehicle roll angle and a vehicle course angle are obtained through velocity and acceleration integration; triaxial sensors are typically integrated into an electronic stability control system of a vehicle.

However, the triaxial gyroscope is sensitive to temperature, has a zero offset phenomenon, and may have deviation even if corrected, so the arrangement needs to be as far away from a heat source as possible; the triaxial acceleration sensor is sensitive to vibration, so that the arrangement position is required to be far away from a vibration source as far as possible, and meanwhile, the cost is increased due to the fact that damping treatment needs to be carried out between the sensor and a vehicle body; in addition, after a triaxial sensor, a gyroscope and the like are generally integrated with an electronic stability control system, the sensor can only be arranged in an engine room in order to meet the connection between the electronic stability control system and a brake pipeline, and the risk of damage after collision exists.

In addition, in the prior art, a position vector is constructed by at least two positioning modules arranged at different positions on the vehicle, and the vector can be changed in the driving process of the vehicle and compared with a stored initial position vector, so that the current posture of the vehicle can be obtained. But this solution does not allow to calculate the vehicle steering angular velocity; therefore, in order to ensure the calculation accuracy, at least 3 positioning modules are needed, 3 groups of position vectors are generated, the change of the 3 groups of position vectors needs to be compared firstly during calculation, 2 times of coordinate system conversion of acceleration is needed, then difference processing is carried out, and the vehicle attitude change value can be obtained.

Disclosure of Invention

The invention mainly aims to provide a novel vehicle attitude calculation method which is not influenced by temperature and humidity and is simple and reliable.

The technical scheme adopted by the invention is as follows:

the vehicle attitude calculation method based on the satellite positioning system comprises the following steps:

calibrating when the vehicle leaves a factory to obtain fixed coordinates of the three satellite positioning modules in a finished vehicle attitude coordinate system, comparing the fixed coordinates with coordinates in a satellite positioning system, and establishing an initial conversion relation between the finished vehicle attitude coordinate system and a geocentric coordinate system as an initial attitude of the vehicle; the three satellite positioning modules are arranged at different positions of the vehicle;

in the using process of the vehicle, the coordinates of the satellite positioning systems of the three satellite positioning modules at different moments are obtained and compared with the fixed coordinates in the attitude coordinate system of the whole vehicle to obtain the real-time conversion relation between the attitude coordinate system of the whole vehicle and the geocentric coordinate system, and the difference value between the real-time conversion relation and the initial conversion relation is the change of the real-time attitude of the vehicle compared with the initial attitude.

According to the technical scheme, a plurality of analysis units are distributed on the vehicle and are endowed with different weights, and each analysis unit comprises at least three satellite positioning modules and a calculation analysis module.

According to the technical scheme, if one satellite positioning module in one analysis unit is damaged, the analysis unit is shielded.

In the technical scheme, the coordinate system is converted by a quaternion method or a rotational matrix method.

According to the technical scheme, when the coordinate system is converted by a rotation matrix method, the conversion relation between the coordinates of the three satellite positioning modules in the whole vehicle attitude coordinate system and the coordinates in the geocentric coordinate system is established by the rotation matrix method, the rotation angle converted from the whole vehicle attitude coordinate system to the geocentric coordinate system in the initial state and the real-time state is obtained, the rotation angles in the X axis and the Y axis are subtracted to obtain the pitch angle and the roll angle, and the time derivation is carried out on the rotation angle around the Z axis to obtain the angular velocity.

The invention also provides a vehicle attitude calculation system based on a satellite positioning system, which comprises at least one analysis unit, wherein the analysis unit comprises:

at least three satellite positioning modules arranged at different positions of the vehicle;

a calculation and analysis module, connected to the satellite positioning module, for calculating the vehicle attitude, in particular for: obtaining fixed coordinates of the three satellite positioning modules in a finished automobile attitude coordinate system through calibration when the automobile leaves a factory, comparing the fixed coordinates with coordinates in a satellite positioning system, and establishing an initial conversion relation between the finished automobile attitude coordinate system and a geocentric coordinate system to be used as an initial attitude of the automobile;

in the using process of the vehicle, the coordinates of the satellite positioning systems of the three satellite positioning modules at different moments are obtained and compared with the fixed coordinates in the attitude coordinate system of the whole vehicle to obtain the real-time conversion relation between the attitude coordinate system of the whole vehicle and the geocentric coordinate system, and the difference value between the real-time conversion relation and the initial conversion relation is the change of the real-time attitude of the vehicle compared with the initial attitude.

In the above-described technical solution, a plurality of analysis units are arranged on a vehicle and are given different weights.

According to the technical scheme, if one satellite positioning module in one analysis unit is damaged, the analysis unit is shielded.

According to the technical scheme, the calculation and analysis module specifically performs coordinate system conversion through a quaternion method or a rotation matrix method.

According to the technical scheme, when the calculation analysis module carries out coordinate system conversion through a rotation matrix method, specifically, a conversion relation between two coordinate systems is established through a rotation matrix method for coordinates of three satellite positioning modules in a finished automobile attitude coordinate system and coordinates in a geocentric coordinate system, a rotation angle converted from the finished automobile attitude coordinate system to the geocentric coordinate system in an initial state and a real-time state is obtained, rotation angles in two directions of an X axis and a Y axis are subtracted, a pitch angle and a roll angle are obtained, and time derivation is carried out on the rotation angle around the Z axis, so that an angular velocity is obtained.

According to the technical scheme, the satellite positioning module is arranged in a passenger compartment of the vehicle.

The invention has the following beneficial effects: the invention obtains the coordinates through installing a satellite positioning system on the vehicle and a satellite positioning module, and then compares the coordinates with the fixed coordinates in the whole vehicle attitude coordinate system to obtain the real-time conversion relation between the whole vehicle attitude coordinate system and the geocentric coordinate system, and the difference value between the real-time conversion relation and the initial conversion relation is the change of the real-time attitude of the vehicle compared with the initial attitude, thereby calculating the vehicle attitude.

Furthermore, the satellite positioning module arranged in the passenger compartment is safer, is slightly influenced by temperature and vibration, and reduces the cost caused by shock absorption measures required after being integrated with an electronic stability control system.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic structural diagram of a vehicle arrangement according to an embodiment of the invention;

FIG. 2 is a schematic diagram of a vehicle attitude coordinate system and a geocentric coordinate system according to an embodiment of the invention;

FIG. 3 is a schematic diagram of a transformation between a vehicle attitude coordinate system and a geocentric coordinate system according to an embodiment of the invention;

FIG. 4 is a flowchart of a vehicle attitude calculation method based on a satellite positioning system according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The vehicle attitude calculation system based on the satellite positioning system of the present invention, as shown in the figure, comprises: the system comprises at least three satellite positioning modules and a calculation and analysis module, wherein the satellite positioning modules and the calculation and analysis module are arranged at different positions of a vehicle. Three satellite positioning modules can be used as an analysis unit, and the calculation analysis module carries out calculation to obtain the vehicle attitude angle.

Furthermore, in order to obtain more accurate calculation results, the number of satellite positioning modules can be increased to construct more analysis units, the accuracy of each analysis unit is determined in the calibration stage, different weights are assigned to the analysis units to obtain final output results, and meanwhile, after an individual positioning module is damaged, the relevant units are shielded, and calculation results can still be provided.

The satellite positioning module can be arranged in a passenger cabin, so that the satellite positioning module is safer, is slightly influenced by temperature and vibration, and reduces the cost caused by shock absorption measures required after being integrated with an electronic stability control system.

And (3) constructing a finished automobile attitude coordinate system by taking the front direction of the finished automobile as the positive direction of an X axis, the left side in the transverse direction as the positive direction of a Y axis and the vertical direction as a Z axis (as shown in figure 2, a schematic diagram of the finished automobile attitude coordinate system and a geocentric coordinate system). Taking an analysis unit composed of three positioning modules as an example, the three positioning modules need to be installed at different positions on the vehicle. When the vehicle leaves a factory, fixed coordinates of the three positioning modules in a finished vehicle attitude coordinate system are obtained through calibration, and an initial conversion relation (a diagram of the conversion between a finished vehicle attitude coordinate system and a geocentric coordinate system in the figure III) between the finished vehicle attitude coordinate system and the geocentric coordinate system is established through comparison with coordinates of a satellite positioning system and serves as an initial attitude of the vehicle. In the using process of the vehicle, the real-time conversion relation between the whole vehicle attitude coordinate system and the geocentric coordinate system is obtained by comparing the coordinates of the satellite positioning systems of the three positioning modules at different moments with the fixed coordinates in the whole vehicle attitude coordinate system, and the difference value of the real-time conversion relation and the initial conversion relation is the change of the real-time attitude of the vehicle compared with the initial attitude.

There are many methods for converting the coordinate system, and a quaternion method, a rotation matrix method, or other methods may be used.

The embodiment of the invention takes a rotation matrix method as an example, and coordinates of three satellite positioning modules in an analysis unit under a finished automobile attitude coordinate system are^vehicleA(X_V1,Y_V1,Z_V1),^vehicleB(X_V2,Y_V2,Z_V2),^vehicle C(X_V3,Y_V3,Z_V3) The coordinates in the geocentric coordinate system are^wordA(X_W1,Y_W1,Z_W1),^wordB(X_W2,Y_W2,Z_W2),^word C(X_W3,Y_W3,Z_W3). According to the rotation matrix method, all points in the whole vehicle attitude coordinate system respectively rotate the angles of alpha, beta and gamma by winding the X axis, the Y axis and the Z axis of the whole vehicle attitude coordinate system, and then the vector T is translated in the whole vehicle attitude coordinate system_V-W(X_V-W,Y_V-W,Z_V-W) Obtaining the coordinates under the geocentric coordinate system, which is shown in formula (1):

wherein the content of the first and second substances,

in an initial state, three satellite positioning modules can be respectively arranged in a whole vehicle attitude coordinate system^vehicleA(X_V10,Y_V10,Z_V10),^vehicleB(X_V20,Y_V20,Z_V20),^vehicle C(X_V30,Y_V30,Z_V30) Location. The vehicle is calibrated before leaving the factory, and the coordinates of the installation positions of the three satellite positioning modules under the geocentric coordinate system can be obtained through the satellite positioning system^wordA(X_W10,Y_W10,Z_W10),^wordB(X_W20,Y_W20,Z_W20),^word C(X_W30,Y_W30,Z_W30). Substituting the two sets of data into formula 1 to obtain the coordinate system conversion angle alpha in the initial state₀、β₀、γ₀。

In the using process of the vehicle, along with the difference of the vehicle postures, the coordinate systems of the three positioning modules in the satellite positioning system also change, and the coordinates of the three positioning modules are assumed to be respectively the coordinates of the three positioning modules at the time t^wordA′(X_W10,Y_W10,Z_W10),^wordB′(X_W20,Y_W20,Z_W20),^word C′(X_W30,Y_W30,Z_W30). Under the whole vehicle attitude coordinate system, the position of the satellite positioning module is relatively fixed and is all fixed^vehicleA(X_V10,Y_V10,Z_V10),^vehicleB(X_V20,Y_V20,Z_V20),^vehicle C(X_V30,Y_V30,Z_V30). These two sets of data are substituted into equation 1 to obtain the coordinate system conversion angles α ', β', γ 'at time t'. According to the formula (2), vehicle body attitude angles Δ α, Δ β, Δ γ are obtained.

Wherein, the delta alpha is the angle of the vehicle rotating around the X axis of the whole vehicle attitude coordinate system, namely the pitch angle. And delta beta is the angle of rotation of the vehicle around the Y axis of the whole vehicle attitude coordinate system, namely the roll angle. And delta gamma is the angle of the vehicle rotating around the Z axis of the whole vehicle attitude coordinate system, namely the angle of rotation around the Z axis of the whole vehicle attitude coordinate system when the vehicle is compared with the vehicle attitude during initial calibration in a real-time state, and time derivation is carried out on the angle of rotation around the Z axis of the whole vehicle attitude coordinate system, so that the angular velocity w of the vehicle rotating around the Z axis of the whole vehicle attitude coordinate system can be obtained, namely a formula 3.

If more than 3 positioning modules are provided, multiple computational analysis modules may be combined. The calculation analysis module can be integrated with one of the positioning modules or other controllers or can be independently used as a part.

As shown in fig. 4, the vehicle attitude calculation method based on the satellite positioning system according to the embodiment of the present invention mainly includes the following steps:

the method comprises the steps that initial positions (namely original positions) are fixed when a vehicle leaves a factory, fixed coordinates of three satellite positioning modules in a whole vehicle attitude coordinate system are obtained and are compared with coordinates in a satellite positioning system, and an initial conversion relation between the whole vehicle attitude coordinate system and a geocentric coordinate system is established and used as initial attitudes of the vehicle; the three satellite positioning modules are arranged at different positions of the vehicle;

in the using process of the vehicle, the coordinates of the satellite positioning systems of the three satellite positioning modules at different moments are obtained and compared with the fixed coordinates in the attitude coordinate system of the whole vehicle to obtain the real-time conversion relation between the attitude coordinate system of the whole vehicle and the geocentric coordinate system, and the difference value between the real-time conversion relation and the initial conversion relation is the change of the real-time attitude of the vehicle compared with the initial attitude.

In this case, the coordinate system may be converted by various methods, not limited to the rotation matrix method of the above embodiment.

The invention is based on a satellite positioning system with higher and higher precision, the coordinates are obtained through the positioning module, and the vehicle attitude angle can be directly calculated after the coordinate system is converted, thereby providing a brand new solution for calculating the vehicle attitude.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.