CN-117805876-B - Unmanned aerial vehicle ground height estimation method and device, unmanned aerial vehicle and medium

CN117805876BCN 117805876 BCN117805876 BCN 117805876BCN-117805876-B

Abstract

The embodiment of the application relates to the field of unmanned aerial vehicles and discloses a method and a device for estimating ground height of an unmanned aerial vehicle, the unmanned aerial vehicle and a medium. The method comprises the steps of predicting the state variable and covariance of the current moment through new I MU data based on the state variable and covariance corresponding to the state variable of the previous moment when new I MU data are received, measuring and updating the state variable and covariance of the current moment based on optical flow data of the current moment and/or GPS data to correct the relation between the horizontal speed and/or the horizontal speed and the ground height of the unmanned aerial vehicle so as to correct the ground height, and taking the corrected ground height as the ground height of the current moment when the updated covariance is smaller than a preset error. The application utilizes the existing sensor of the unmanned aerial vehicle to integrate the I MU data, the optical flow data and even the GPS data, thereby realizing the estimation of the ground height. When the height sensor fails, an alternative height estimation mode is provided, the reliability of the unmanned aerial vehicle height estimation is improved, and the range is larger.

Inventors

SHEN BINJUN

Assignees

深圳深海创新技术有限公司

Dates

Publication Date: 20260505
Application Date: 20231229

Claims (9)

1. A method for estimating ground altitude of an unmanned aerial vehicle, the method comprising: receiving observation data, wherein the observation data comprises IMU data, optical flow data and GPS data; When new IMU data is received, predicting the state variable and covariance of the current moment through the new IMU data based on the state variable of the last moment and the covariance corresponding to the state variable, wherein the state variable comprises the ground height of the unmanned aerial vehicle and the horizontal speed of the unmanned aerial vehicle under an organism coordinate system; based on the optical flow data at the current time, performing measurement update on the state variable and covariance at the current time, or Based on the optical flow data and the GPS data at the current time, performing measurement update on the state variable and the covariance at the current time to correct the horizontal velocity and the earth-to-ground altitude; And when the updated covariance is smaller than a preset error, taking the corrected ground height as the ground height at the current moment.
2. The method according to claim 1, wherein the method further comprises: Based on the horizontal speed of the unmanned aerial vehicle under the machine body coordinate system, the horizontal axial zero offset of the accelerometer of the unmanned aerial vehicle and the ground height of the unmanned aerial vehicle, a state variable equation and a covariance matrix are constructed.
3. The method of claim 2, wherein when new IMU data is received, predicting state variables and covariances at a current time by the new IMU data based on the state variables and covariances corresponding to the state variables at a previous time, wherein the state variables include ground altitude of the unmanned aerial vehicle and horizontal speed of the unmanned aerial vehicle in an organism coordinate system, comprising: when new IMU data is received, eliminating the gravity acceleration in the new IMU data; Predicting the ground height and the horizontal speed of the unmanned aerial vehicle in the state variables at the current moment based on the IMU data with the gravitational acceleration removed, the horizontal speed at the last moment, the horizontal axial zero offset of the accelerometer of the unmanned aerial vehicle and the ground height of the unmanned aerial vehicle; the covariance at the current time is predicted based on the measured value of the accelerometer of the unmanned aerial vehicle at the previous time, accelerometer zero bias, and the noise of the ground altitude.
4. The method of claim 2, wherein the measuring updates the state variables and covariance at the current time based on the optical flow data at the current time, comprising: Acquiring a first included angle of the unmanned aerial vehicle, which is deviated from a horizontal plane; The first optical flow measurement at the current moment is calculated based on the following formula, Wherein, the Represents the horizontal speed of the unmanned aerial vehicle under the coordinate system of the machine body, h represents the ground height of the unmanned aerial vehicle, For the first included angle of the first set of angles, A first measurement error representing an equivalent angular velocity in the optical flow data, d representing the ground height after the angle compensation; and based on the first optical flow measured value at the current moment, carrying out measurement updating on the state variable and covariance at the current moment.
5. The method of claim 2, wherein the performing a measurement update on the state variable and the covariance at the current time based on the optical flow data and the GPS data at the current time comprises: If the error between the gesture and the horizontal gesture of the unmanned aerial vehicle is in an error range at the current moment, acquiring the GPS data; and based on the module value of the horizontal speed and the optical flow data in the GPS data, carrying out measurement updating on the state variable and the covariance of the current moment.
6. The method of claim 5, wherein the model of the horizontal velocity in the GPS data is obtained based on the following formula: Wherein, the A modulus value representing the horizontal velocity in the GPS data, The noise that is indicative of the GPS data, A model value representing the horizontal speed of the unmanned aerial vehicle in the body coordinate system.
7. An unmanned aerial vehicle ground height estimation device, the device comprising: The system comprises an observation data receiving module, a data processing module and a data processing module, wherein the observation data receiving module is used for receiving observation data, and the observation data comprises IMU data, optical flow data and GPS data; The system comprises a prediction module, a control module and a control module, wherein the prediction module is used for predicting the state variable and the covariance of the current moment through the new IMU data based on the state variable of the last moment and the covariance corresponding to the state variable when receiving the new IMU data, wherein the state variable comprises the ground height of the unmanned aerial vehicle and the horizontal speed of the unmanned aerial vehicle under an organism coordinate system; An update module configured to perform measurement update on the state variable and covariance at the current time based on the optical flow data at the current time, or perform measurement update on the state variable and covariance at the current time based on the optical flow data and the GPS data at the current time, so as to correct the horizontal velocity and the ground altitude; and the determining module is used for taking the corrected ground height as the ground height at the current moment when the updated covariance is smaller than a preset error.
8. The unmanned aerial vehicle is characterized by comprising a flight control module, an IMU module, a GPS module and an optical flow module, wherein the flight control module is respectively connected with the IMU module, the GPS module and the optical flow module; the flight control module includes a processor and a memory communicatively coupled to the processor, the memory storing instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-6.
9. A non-transitory computer readable storage medium storing computer executable instructions which, when executed by a drone, cause the drone to perform the method of any one of claims 1-6.

Description

Unmanned aerial vehicle ground height estimation method and device, unmanned aerial vehicle and medium Technical Field The embodiment of the application relates to the technical field of unmanned aerial vehicles, in particular to a method and a device for estimating ground height of an unmanned aerial vehicle, the unmanned aerial vehicle and a medium. Background Ground altitude estimation is a technique that is critical in unmanned aerial vehicle applications. In unmanned aerial vehicle's flight control, to ground altitude estimation is the prerequisite that realizes autonomous flight and location, and it not only can help unmanned aerial vehicle to avoid the barrier, can also ensure unmanned aerial vehicle's accurate location and control under different altitudes. The development and application of the ground height estimation technology not only can improve the flight safety and precision of the unmanned aerial vehicle, but also can expand the application fields of the unmanned aerial vehicle, such as the fields of unmanned aerial vehicle distribution, agricultural plant protection, traffic monitoring and the like, and has wide application prospects for the ground height estimation technology. In the prior art, a ground height estimation method commonly used by unmanned aerial vehicles generally adopts an ultrasonic sensor, a laser radar and binocular vision ranging. The unmanned plane adopts an ultrasonic sensor to estimate the ground height, which is an economical method, but the measurement distance is generally short, usually 3 meters to 5 meters, and the unmanned plane is easy to be interfered, and the detection view angle is large. The unmanned aerial vehicle adopts laser radar to the estimation of ground altitude more accurate than ultrasonic sensor, but the price is higher, and ordinary single-point laser measurement distance is usually not more than 10 meters, and remote laser ranging's price is more expensive. Binocular vision range finding is comparatively novel to ground altitude estimation, can acquire depth information through the camera, but binocular module's measurement accuracy relies on the accuracy of demarcating to, need a large amount of computational resource, it is higher to the platform performance requirement. Disclosure of Invention The embodiment of the application aims to provide a method, a device, an unmanned aerial vehicle and a medium for estimating the ground height of the unmanned aerial vehicle, which utilize the existing sensor of the unmanned aerial vehicle to realize the estimation of the ground height of the unmanned aerial vehicle by fusing IMU data, optical flow data and GPS data, avoid the situation that the height cannot be estimated when a single sensor fails and improve the reliability of the ground estimation. In order to solve the technical problems, the embodiment of the application adopts the following technical scheme: in a first aspect, an embodiment of the present application provides a method for estimating a ground altitude of a unmanned aerial vehicle, where the method includes: Receiving observation data, wherein the observation data comprises IMU data and at least one of optical flow data and GPS data; when new IMU data is received, predicting the state variable and covariance of the current moment through the new IMU data based on the state variable of the last moment and the covariance corresponding to the state variable, wherein the state variable comprises the horizontal speed of the unmanned aerial vehicle under a machine body coordinate system; Measuring and updating the state variable and covariance of the current moment based on the optical flow data of the current moment to correct the relation between the horizontal speed and the ground altitude of the unmanned aerial vehicle, and/or measuring and updating the state variable and covariance of the current moment based on the GPS data of the current moment to correct the horizontal speed and further correct the ground altitude; And when the updated covariance is smaller than a preset error, taking the corrected ground height as the ground height at the current moment. In some embodiments, the method further comprises: Based on the horizontal speed of the unmanned aerial vehicle under the machine body coordinate system, the horizontal axial zero offset of the accelerometer of the unmanned aerial vehicle and the ground height of the unmanned aerial vehicle, a state variable equation and a covariance matrix are constructed. In some embodiments, when new IMU data is received, based on a state variable at a previous time and a covariance corresponding to the state variable, predicting the state variable and the covariance at the current time by the new IMU data, where the state variable includes a horizontal speed of the unmanned aerial vehicle in a body coordinate system, and the method includes: when new IMU data is received, eliminating the gravity acceleration in the new IMU data; predicting