Course angle measuring device and method, computing device, and storage medium

Abstract

The application provides a heading angle measuring device and method, a computing device and a storage medium. The heading angle measuring device of the vehicle comprises: a GNSS receiver mounted on the vehicle, which is also used to calculate a first speed difference between a current time and a previous time based on a positioning solution; an inertial measurement unit mounted on the vehicle, which outputs an acceleration value sequence composed of a series of acceleration values, and calculates a second speed difference between the current time and the previous time based on the output acceleration values; and a control unit configured to determine whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly based on the first speed difference and the second speed difference between the current time and the previous time, and initialize the heading angle of the integrated navigation using the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating rapidly. In this way, the rapid initialization of the heading angle of the integrated navigation can be realized in a low-speed scenario.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of navigation positioning, and in particular to a heading angle measuring device and method, a computing device and a storage medium. BACKGROUND

[0002] The measurement of the heading angle is crucial for autonomous driving, and is traditionally mainly based on a combined navigation scheme based on GNSS (Global Navigation Satellite System) + IMU (Inertial Measurement Unit). However, for low-speed carriers (such as agricultural tractors and park logistics trolleys), the normal driving speed thereof can be even lower than 1 km / h, and the traditional combined navigation-based scheme can have problems such as poor precision, and even failure to complete the measurement of the heading angle or errors in the measurement of the heading angle due to the low speed of the vehicle or the inability to determine the driving direction of the vehicle.

[0003] To solve the high-precision measurement of the heading angle in the low-speed scenario, the existing schemes mainly have the following two kinds. The first kind is a dual-antenna RTK (Real Time Kinematics), and whether to join an IMU to form a combined navigation system is selected according to the use scenario. The RTK in this scheme needs to input external correction information through a communication mode such as radio or the Internet, and has poor robustness, and the use of dual antennas also brings an increase in cost. The second kind of scheme adopts a geomagnetic sensor, and whether to join an IMU to form a combined navigation system is selected according to the use scenario. The problem of this scheme is that the magnetic heading and the geographic heading have a magnetic declination angle, and the geomagnetic field is easily disturbed.

[0004] Therefore, it is necessary to propose an improved scheme to overcome the related problems. SUMMARY

[0005] The present application relates to the field of navigation positioning, and in particular to a heading angle measuring device and method, a computing device and a storage medium.

[0006] To achieve the object, according to one aspect of the present application, the present application provides a heading angle measuring device of a vehicle, comprising: a GNSS receiver mounted on the vehicle, configured to receive satellite observation signals, and obtain a positioning solution sequence composed of a series of positioning solutions based on the satellite observation signals, the positioning solutions comprising velocity, heading angle, time and position, and further configured to calculate a first velocity difference between a current time and a previous time based on the velocity in the positioning solutions; an inertial measurement unit mounted on the vehicle, configured to sense acceleration of the vehicle and output an acceleration value sequence composed of a series of acceleration values, and obtain a second velocity difference between the current time and the previous time based on the output acceleration values; and a control unit configured to determine whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly based on the first velocity difference and the second velocity difference between the current time and the previous time, and initialize the heading angle of the integrated navigation using the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating rapidly.

[0007] According to one aspect of the present application, the present application provides a heading angle measuring method of a vehicle, comprising: receiving satellite observation signals, and obtaining a positioning solution sequence composed of a series of positioning solutions based on the satellite observation signals, the positioning solutions comprising velocity, heading angle, time and position, and further configured to calculate a first velocity difference between a current time and a previous time based on the velocity in the positioning solutions; sensing acceleration of the vehicle and outputting an acceleration value sequence composed of a series of acceleration values, and obtaining a second velocity difference between the current time and the previous time based on the output acceleration values; and determining whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly based on the first velocity difference and the second velocity difference between the current time and the previous time, and initializing the heading angle of the integrated navigation using the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating rapidly.

[0008] According to another aspect of the present application, the present application provides a computing device comprising a processor and a memory, the memory storing program instructions executed by the processor to implement the above-mentioned heading angle measuring method.

[0009] According to still another aspect of the present application, the present application provides a storage medium storing program instructions executed to implement the above-mentioned heading angle measuring method.

[0010] Compared with the prior art, the present application determines whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating by combining the speed change obtained by the GNSS receiver and the speed change obtained by the inertial measurement unit, and determines whether to initialize the heading angle of the integrated navigation using the heading angle in the current positioning solution based on the determination structure. In this way, the heading angle of the integrated navigation algorithm can be quickly initialized in a low-speed scenario. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Structure block diagram of the heading angle measuring device for the vehicle in the application in one embodiment;

[0012] Figure 2 Installation schematic diagram of the heading angle measuring device in the application in the vehicle.

[0013] Figure 3 Flow chart of the heading angle measuring method for the vehicle in the application in one embodiment.

[0014] Figure 4 Test result diagram of the heading angle measuring device for the vehicle in the application when initializing the heading angle.

[0015] Figure 5 For Figure 4 Enlarged schematic diagram of one area in the test result diagram. DETAILED DESCRIPTION

[0016] In order to further illustrate the technical means and effects adopted by the application to achieve the predetermined purposes and effects, the specific embodiments, structures, features and effects according to the application are described in detail below in combination with the drawings and preferred embodiments.

[0017] The application is improved based on the traditional combination navigation scheme of GNSS receiver + IMU (inertial measurement unit), judges whether the vehicle is driving forward and whether the vehicle is accelerating or decelerating by combining the speed change obtained by the GNSS receiver and the speed change obtained by the inertial measurement unit, and determines whether to initialize the heading angle of the combination navigation using the heading angle in the current positioning solution based on the judging structure, so that the rapid initialization of the heading angle of the combination navigation algorithm can be realized in the low-speed scene.

[0018] Figure 1 Structure block diagram of the heading angle measuring device for the vehicle in the application in one embodiment; Figure 2 Installation schematic diagram of the heading angle measuring device in the application in the vehicle.

[0019] As Figure 1As shown, the heading angle measuring device 100 includes a GNSS receiver 110 and an inertial measurement unit 120. The GNSS receiver 110 is connected to a GNSS antenna 150. The GNSS receiver 110 is connected to the inertial measurement unit 120 through a first interface, which can be a UART (Universal Asynchronous Receiver / Transmitter) interface. The inertial measurement unit 120 is connected to a host computer 200 through a second interface, which can also be a UART interface. In other embodiments, the first and second interfaces can also be other types of interfaces, and the types of the first and second interfaces can be the same or different. The heading angle measuring device 100 and the GNSS antenna 150 are mounted on the vehicle 10.

[0020] like Figure 2 As shown in this document, the X-axis of the inertial measurement unit 120 points along the longitudinal axis of the vehicle in the direction of vehicle travel, the Y-axis of the inertial measurement unit 120 points to the right side of the vehicle, and the Z-axis of the inertial measurement unit 120 points vertically downward.

[0021] The GNSS receiver 110 is configured to receive satellite observation signals via the GNSS antenna 150, and obtain a sequence of positioning solutions based on the satellite observation signals. The positioning solutions can be output at a first predetermined frequency, such as 1 Hz, meaning one positioning solution is output every second. The positioning solution includes velocity, heading angle, time, and position, where the heading angle can be calculated from the velocity in the positioning solution. In some applications, the heading angle may not be included as a parameter in the positioning solution, but it is included in this document. The inertial measurement unit 120 also includes an accelerometer and a gyroscope. The inertial measurement unit 120 is configured to sense the vehicle's acceleration and output a sequence of acceleration values. The acceleration can be output at a second predetermined frequency, such as 100 Hz, meaning 100 acceleration values ​​are output per second.

[0022] exist Figure 1In the embodiment shown, the control unit is included in the inertial measurement unit 120. The control unit can perform combined navigation of GNSS and IMU. The control unit can perform initialization of the heading angle for combined navigation, and thus realize measurement of the heading angle. However, in a modified embodiment, the control unit can also be arranged in the GNSS receiver 110. In another alternative embodiment, part of the control unit is arranged in the GNSS receiver 110, and part of the control unit is arranged in the inertial measurement unit 120. In yet another alternative embodiment, the control unit can be independent of the GNSS receiver 110 and the inertial measurement unit 120, i.e. the control unit is arranged separately, and receives positioning solutions from the GNSS receiver 110 and receives inertial measurement data from the inertial measurement unit 120. The inertial measurement unit 120 includes a Kalman filter.

[0023] The control unit is configured to calculate a first speed difference between a current time and a previous time based on a speed in a positioning solution output by the GNSS receiver 110, and to calculate a second speed difference between the current time and the previous time based on an acceleration value output by the inertial measurement unit 120.

[0024] In one embodiment, a first speed difference δv gnss (k+δt) of a GNSS speed v gnss (k) at a time t(k+δt) (which can be referred to as a current time) relative to a GNSS speed v gnss (k) at a time t(k) (which can be referred to as a previous time) is calculated.

[0025] δv gnss (t+δt) = v gnss (k+δt) - v gnss (k) # (1)

[0026] In one embodiment, the time interval δt is set to 1 second, taking into account the output frequency of the GNSS receiver 110 and the speed measurement noise.

[0027] In one embodiment, a second speed difference δv imu (t+δt) is calculated by integrating the acceleration of the vehicle body axis output by the inertial measurement unit 120 over a time period from t(k) to t(k+δt).

[0028]

[0029] where a x is the acceleration of the vehicle body axis, and dτ is the sampling interval output by the inertial measurement unit 120.

[0030] the control unit judges whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly based on the first speed difference δv gnss (t+δt) and the second speed difference δv imu (t+δt). When the vehicle is moving forward and accelerating or decelerating rapidly, the heading angle of the integrated navigation is initialized using the heading angle in the positioning solution output by the GNSS receiver 110. The heading angle measurement device sends the initialized heading angle of the integrated navigation to the host computer 200.

[0031] Specifically, when the absolute values of the first speed difference δv gnss (t+δt) and the second speed difference δv imu (t+δt) at the current time and the previous time are both greater than or equal to a first acceleration threshold, it is considered that the vehicle is accelerating or decelerating rapidly. For example, the first acceleration threshold can be 0.5 m / s 2 . When the absolute values of the first speed difference δv gnss (t+δt) and the second speed difference δv imu (t+δt) at the current time and the previous time are both greater than or equal to a first acceleration threshold, it is considered that the vehicle is accelerating or decelerating rapidly. For example, the first acceleration threshold can be 0.5 m / s gnss (t+δt) and the second speed difference δv imu (t+δt) at the current time and the previous time are the same, it is considered that the vehicle is moving forward, and the heading angle in the positioning solution output by the GNSS receiver 110 is the same as the actual heading of the vehicle body and can be used to initialize the heading angle of the integrated navigation. Conversely, when the signs of the first speed difference δv gnss (t+δt) and the second speed difference δv imu (t+δt) at the current time and the previous time are opposite, it is considered that the vehicle is not moving forward, for example, it can be considered that the vehicle is reversing, and the heading angle in the positioning solution output by the GNSS receiver 110 is about 180 degrees different from the actual heading of the vehicle body and cannot be used to initialize the heading angle of the integrated navigation.

[0032] the control unit judges whether the vehicle is accelerating or decelerating slowly based on the first speed difference δv gnss (t+δt) and the second speed difference δv imu (t+δt) at the current time and the previous time. When the vehicle is moving forward and accelerating or decelerating slowly, the heading angle of the integrated navigation is initialized using the heading angle in the positioning solution output by the GNSS receiver 110.

[0033] When the absolute values of the first speed difference δv gnss (t+δt) and the second speed difference δv imu (t+δt) at the current time and the previous time are both greater than or equal to a second acceleration threshold and less than the first acceleration threshold for N consecutive times, where N is greater than or equal to 2, it is considered that the vehicle is accelerating or decelerating slowly. For example, the second acceleration threshold can be 0.2 m / s 2It is noted that, assuming N=2, at the first time of judgment, whether the absolute values of the first speed difference δv gnss (t+δt) and the second speed difference δv imu (t+δt) are both greater than or equal to the second acceleration threshold value and less than the first acceleration threshold value, if yes, it means that the current vehicle is very likely to be accelerating or decelerating slowly, and there is a small possibility that both the GNSS receiver and the inertial measurement unit 120 have errors. Therefore, it is necessary to continue the second time of judgment at the next time, i.e., to continue to judge the absolute values of the first speed difference δv gnss (t+2δt) and the second speed difference δv imu (t+2δt) at the next time as the current time and the previous time, if yes, it means that the current vehicle is accelerating or decelerating slowly. Similarly, it is still judged whether the vehicle is moving forward by whether the signs of the first speed difference and the second speed difference are the same. Of course, it is also possible to continuously judge for three times or more.

[0034] In a preferred embodiment, the control unit is further configured to perform the following operation: saving the heading angle, the speed and the time in the positioning solution output by the GNSS receiver and the Z-axis angular velocity of the gyroscope of the inertial measurement unit 120 to a buffer; when initializing the heading angle of the integrated navigation with the heading angle in the current positioning solution, judging whether the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation, if yes, initializing the heading angle of the integrated navigation based on the heading angle in the previous positioning solution and the heading angle in the current positioning solution. Specifically, initializing the heading angle of the integrated navigation with the average heading angle of the heading angle in the previous positioning solution and the heading angle in the current positioning solution. The previous positioning solution is the positioning solution before the current positioning solution, and the previous positioning solution can be one previous positioning solution or multiple previous positioning solutions. Since the measurement error of the heading angle in the positioning solution is large when running at low speed, it is expected to use the average of the measurement values of the heading angle in multiple positioning solutions to initialize the heading angle of the integrated navigation, so as to reduce the measurement error.

[0035] In one embodiment, the heading angle in the previous positioning solution in the buffer is considered to be used to initialize the heading angle of the integrated navigation when one or more of the following conditions are met: 1) the time difference between the two adjacent positioning solutions is less than or equal to a predetermined time length, such as 1 second, to ensure that no GNSS signal loss occurs during the period; 2) the speed in each positioning solution is not less than a minimum speed threshold, such as 0.5 m / s; 3) the absolute value of the angular velocity of the numerical axis of the gyroscope is less than a predetermined angular velocity threshold, such as 6 deg / s, to ensure that the vehicle does not turn during the period; and 4) the change of the heading angle in the previous positioning solution and the heading angle in the current positioning solution does not exceed a predetermined angle threshold, such as 20 degrees. Preferably, the heading angle in the previous positioning solution in the buffer is considered to be used to initialize the heading angle of the integrated navigation when all the above four conditions are met.

[0036] Thus, the application can achieve rapid initialization of the heading angle of the integrated navigation under low-speed driving, and avoid initialization error of the heading angle caused by reversing. Moreover, by selecting a sequence of GNSS heading angles (i.e. the heading angles obtained by the GNSS receiver) that meet the conditions, the influence of the GNSS heading angle measurement error on the initialization of the integrated navigation is reduced as much as possible.

[0037] Figure 4 A test result graph of the heading angle measurement device for the vehicle in the application when initializing the heading angle; Figure 5 A test result graph of the heading angle measurement device for the vehicle in the application when initializing the heading angle; Figure 4 An enlarged schematic view of one area in the test result graph.

[0038] From the power-on of the integrated navigation system to t1, the vehicle is at rest. At t1, the vehicle starts to move, but at this time it is reversing. At t2, the vehicle completes reversing and is at rest, and then starts to move forward. At t3, the heading angle of the integrated navigation is initialized. Figure 4 The upper half of the graph in FIG. 1 is the heading angle, wherein "from INS" represents the heading angle from the integrated navigation (INS), "from GNSS" represents the heading angle from the GNSS receiver, and "Ground Truth" represents the heading angle from the reference system as the true value. From t1 to t2, the vehicle is reversing, at this time the GNSS heading angle (i.e. the heading angle from the GNSS receiver) is about 180 degrees different from the true value, i.e. the directions of the two are opposite, and the GNSS heading angle cannot be used to initialize the integrated navigation, at this time the GNSS heading angle starts from the default initial value of 0 degrees, and the heading angle of the integrated navigation is the change relative to the initial value of 0 degrees, rather than the heading angle relative to the geographic north. From t2 to t3, the vehicle starts to move forward, and the heading angle of the integrated navigation is quickly initialized and consistent with the true value. It can also be seen that the measurement noise of the heading angle of the integrated navigation is much better than that of the GNSS.Figure 4 The lower half represents GNSS velocity.

[0039] like Figure 5 As shown, when initializing the integrated navigation heading angle using GNSS heading angles between times t2 and t3, due to the effect of GNSS heading angle time series analysis, the error of the initialized integrated navigation heading angle (integrated navigation heading angle at time t3) is smaller than that of the GNSS heading angle (GNSS heading angle between times t2 and t3). Meanwhile, from... Figure 5 The lower half of the diagram shows that the vehicle speed was less than 1 m / s when the integrated navigation heading angle initialization was completed. This demonstrates that the method and device can achieve fast and accurate integrated navigation heading angle initialization under low-speed conditions.

[0040] According to another aspect of the present invention, the present invention also provides a method for measuring the heading angle of a vehicle. Figure 3 This is a flowchart of one embodiment of the vehicle heading angle measurement method of the present invention. Figure 3 As shown, the vehicle heading angle measurement method 300 includes the following steps.

[0041] Step 310: Receive satellite observation signals and obtain a sequence of positioning solutions based on the satellite observation signals. The positioning solutions include velocity, heading angle, time, and position. Calculate the first velocity difference between the current time and the previous time based on the velocity in the positioning solutions.

[0042] Step 320: Sensing the vehicle's acceleration and outputting a sequence of acceleration values; calculating the second velocity difference between the current moment and the previous moment based on the output acceleration values.

[0043] Step 330: Based on the first speed difference and the second speed difference between the current time and the previous time, determine whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly. When the vehicle is moving forward and accelerating or decelerating rapidly, initialize the heading angle of the integrated navigation using the heading angle in the current positioning solution.

[0044] In one embodiment, if the absolute values ​​of the first speed difference and the second speed difference between the current time and the previous time are both greater than or equal to the first acceleration threshold, the vehicle is considered to be rapidly accelerating or decelerating; if the signs of the first speed difference and the second speed difference between the current time and the previous time are the same, the vehicle is considered to be moving forward; otherwise, the vehicle is considered not to be moving forward.

[0045] The heading angle measurement method 300 further comprises: determining whether the vehicle is accelerating or decelerating slowly based on the first speed difference and the second speed difference at the current time and the previous time, and initializing the heading angle of the integrated navigation with the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating slowly. Specifically, when the absolute values of the first speed difference and the second speed difference at the current time and the previous time are all greater than or equal to the second acceleration threshold and less than the first acceleration threshold for consecutive N times, where N is greater than or equal to 2, it is considered that the vehicle is accelerating or decelerating slowly.

[0046] In one embodiment, the heading angle measurement method further comprises: saving the heading angle, the speed, the time in the positioning solution, and the angular velocity of the Z axis of the gyroscope in the inertial measurement unit to a buffer; when initializing the heading angle of the integrated navigation with the heading angle in the current positioning solution, determining whether the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation, and if so, initializing the heading angle of the integrated navigation based on the heading angle in the previous positioning solution and the heading angle in the current positioning solution.

[0047] Specifically, when one or more of the following conditions are met:

[0048] 1) the time difference between two adjacent positioning solutions is less than or equal to a predetermined time length;

[0049] 2) the speed in each positioning solution is not less than a minimum speed threshold;

[0050] 3) the absolute value of the angular velocity of the numerical axis of the gyroscope is less than a predetermined angular velocity threshold;

[0051] 4) the change of the heading angle in the previous positioning solution and the heading angle in the current positioning solution does not exceed a predetermined angle threshold,

[0052] it is considered that the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation. Preferably, when all the above four conditions are met, it is considered that the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation.

[0053] According to another aspect of the present application, the present application provides a computing device comprising a processor and a memory, wherein the memory stores program instructions executed by the processor to implement the above-mentioned heading angle measurement method.

[0054] According to still another aspect of the present application, the present application provides a storage medium having program instructions stored therein, which are executed to implement the above-mentioned heading angle measurement method.

[0055] In this document, the terms "comprise", "comprising", or any other variation thereof are intended to cover a non-exclusive inclusion, such that a document or method that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such document or method.

[0056] In this document, the terms "comprise", "comprising", or any other variation thereof are intended to cover a non-exclusive inclusion, such that a document or method that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such document or method.

[0057] In the case of no conflict, the above-mentioned embodiments and features in the embodiments can be combined with each other.

[0058] The above description is merely the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A yaw angle measuring device of a vehicle, characterized by comprising: The application relates to a heading angle measuring device for a vehicle, comprising: a GNSS receiver mounted on the vehicle and configured to receive satellite observation signals and to obtain a series of positioning solutions based on the satellite observation signals, wherein each positioning solution comprises a velocity, a heading angle, a time and a position; an inertial measurement unit mounted on the vehicle and configured to sense an acceleration of the vehicle and to output a series of acceleration values; a control unit configured to calculate a first velocity difference between a current time and a previous time based on the velocity in a current positioning solution output by the GNSS receiver, to calculate a second velocity difference between the current time and the previous time based on the acceleration values output by the inertial measurement unit, to determine whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly based on the first and second velocity differences, and to initialize a heading angle of the integrated navigation with the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating rapidly, the vehicle is considered to be accelerating or decelerating rapidly when the absolute values of the first and second velocity differences are greater than or equal to a first acceleration threshold value, the vehicle is considered to be moving forward when the signs of the first and second velocity differences are the same, otherwise, the vehicle is considered not to be moving forward.

2. The heading angle measuring device according to claim 1, wherein the control unit is further configured to determine whether the vehicle is accelerating or decelerating slowly based on the first and second velocity differences, the heading angle of the integrated navigation is initialized with the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating slowly.

3. The heading angle measuring device according to claim 2, wherein the vehicle is considered to be accelerating or decelerating slowly when the absolute values of the first and second velocity differences are greater than or equal to a second acceleration threshold value and less than the first acceleration threshold value for N consecutive times, wherein N is greater than or equal to 2.

4. The heading angle measuring device of claim 1, wherein the control unit is further configured to: save the heading angle, the velocity, the time in the positioning solution and the angular velocity of the Z-axis of the gyroscope in the inertial measurement unit to a buffer, when the heading angle of the integrated navigation is initialized with the heading angle in the current positioning solution, determine whether the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation, and initialize the heading angle of the integrated navigation based on the heading angle in the previous positioning solution and the heading angle in the current positioning solution if the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation.

5. The heading angle measuring device according to claim 4, characterized in that the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation when one or more of the following conditions are met: 1) the time difference between two adjacent positioning solutions is less than or equal to a predetermined time length; 2) the velocity in each positioning solution is not less than a minimum velocity threshold value; 3) the absolute value of the angular velocity of the numerical axis of the gyroscope is less than a predetermined angular velocity threshold value; 4) the change of the heading angle in the previous positioning solution and the heading angle in the current positioning solution does not exceed a predetermined angle threshold value. The application further relates to a heading angle measuring device for a vehicle, comprising:

6. A method of measuring a heading angle of a vehicle, characterized by, a GNSS receiver mounted on the vehicle and configured to receive satellite observation signals and to obtain a series of positioning solutions based on the satellite observation signals, wherein each positioning solution comprises a velocity, a heading angle, a time and a position; an inertial measurement unit mounted on the vehicle and configured to sense an acceleration of the vehicle and to output a series of acceleration values; a control unit configured to calculate a first velocity difference between a current time and a previous time based on the velocity in a current positioning solution output by the GNSS receiver, to calculate a second velocity difference between the current time and the previous time based on the acceleration values output by the inertial measurement unit, to determine whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly based on the first and second velocity differences, and to initialize a heading angle of the integrated navigation with the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating rapidly, the vehicle is considered to be accelerating or decelerating rapidly when the absolute values of the first and second velocity differences are greater than or equal to a first acceleration threshold value, the vehicle is considered to be moving forward when the signs of the first and second velocity differences are the same, otherwise, the vehicle is considered not to be moving forward. receiving satellite observation signals, obtaining a series of positioning solutions based on the satellite observation signals, the positioning solutions including velocity, heading angle, time and position, calculating a first velocity difference between a current time and a previous time based on the velocity in the positioning solutions; sensing acceleration of the vehicle based on an inertial measurement unit and outputting a series of acceleration values, calculating a second velocity difference between the current time and the previous time based on the output acceleration values; determining whether the vehicle is moving forward and whether the vehicle is accelerating or decelerating rapidly based on the first velocity difference and the second velocity difference between the current time and the previous time, initializing the heading angle of the integrated navigation with the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating rapidly, considering that the vehicle is accelerating or decelerating rapidly when the absolute values of the first velocity difference and the second velocity difference between the current time and the previous time are greater than or equal to a first acceleration threshold value, considering that the vehicle is moving forward when the signs of the first velocity difference and the second velocity difference between the current time and the previous time are the same, otherwise, considering that the vehicle is not moving forward.

7. The heading angle measurement method of claim 6, wherein, It further comprises: determining whether the vehicle is accelerating or decelerating slowly based on the first velocity difference and the second velocity difference between the current time and the previous time, initializing the heading angle of the integrated navigation with the heading angle in the current positioning solution when the vehicle is moving forward and accelerating or decelerating slowly.

8. The heading angle measurement method according to claim 7, wherein considering that the vehicle is accelerating or decelerating slowly when the absolute values of the first velocity difference and the second velocity difference between the current time and the previous time are greater than or equal to a second acceleration threshold value and less than the first acceleration threshold value for N consecutive times, where N is greater than or equal to 2.

9. The heading angle measurement method of claim 6, wherein, It further comprises: saving the heading angle, velocity, time in the positioning solution and the Z-axis angular velocity of the gyroscope in the inertial measurement unit to a buffer; when initializing the heading angle of the integrated navigation with the heading angle in the current positioning solution, determining whether the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation, and if so, initializing the heading angle of the integrated navigation based on the heading angle in the previous positioning solution and the heading angle in the current positioning solution.

10. The heading angle measurement method of claim 9, wherein, When one or more of the following conditions are met: 1) the time difference between two adjacent positioning solutions is less than or equal to a predetermined time length; 2) the velocity in each positioning solution is not less than a minimum velocity threshold value; 3) the absolute value of the angular velocity of the numerical axis of the gyroscope is less than a predetermined angular velocity threshold value; 4) the change of the heading angle in the previous positioning solution and the heading angle in the current positioning solution does not exceed a predetermined angle threshold value, it is considered that the heading angle in the previous positioning solution in the buffer can be used to initialize the heading angle of the integrated navigation.

11. A computing device comprising a processor and a memory, the memory having program instructions stored therein, the program instructions being executed by the processor to implement the heading angle measurement method according to any one of claims 6-10.

12. A storage medium having program instructions stored therein, the program instructions being executed to implement the heading angle measurement method according to any one of claims 6-10.

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