A height measurement method and device for ground collision prevention of a FTV and a FTV

Abstract

The present application discloses a method, device and a FPV for measuring the height of a FPV for ground collision avoidance. The method for measuring the height of a FPV for ground collision avoidance includes: selecting the relative height of the FPV at the current moment to the ground, the climbing rate at the current moment and the ultrasonic measurement offset as state variables; constructing a state quantity equation according to the state variables; constructing a measurement prediction equation; performing EKF filtering according to the obtained relative height at the current moment to the ground, the climbing rate at the current moment and the ultrasonic measurement offset to obtain the height information of the FPV. The method for measuring the height of a FPV for ground collision avoidance of the present application adopts a binary vector pointing measurement method. Even if the FPV has a large attitude fluctuation during flight, the height above the ground can be effectively measured, thereby preventing collision with the ground and making the height above the ground controllable.

Description

Technical Field

[0001] The present application relates to the technical field of altitude measurement of FTVs, and in particular to an altitude measurement method for ground collision avoidance of a high-maneuverability FTV and an altitude measurement device for ground collision avoidance of a high-maneuverability FTV. Background Art

[0002] With the rapid development of drone technology, drones, as highly maneuverable unmanned aerial vehicles, are increasingly used in complex aerial missions. These missions usually require drones to fly in high-speed, low-altitude environments, especially in complex terrain and narrow spaces. Due to the complexity of the flight environment and the requirements for maneuverability, drones face a high risk of collision during missions. Traditional drone altitude measurement methods usually rely on technologies such as air pressure sensors, laser rangefinders or GPS, but these methods are difficult to provide real-time and accurate altitude information between the drone and the ground under highly maneuverable and rapidly changing flight conditions. In addition, existing altitude measurement technologies are easily interfered with in complex terrain, resulting in inaccurate or delayed data, which increases the risk of drone collisions. Summary of the invention

[0003] The object of the present invention is to provide a height measurement method for high-maneuverability cross-country aircraft to avoid ground collision, so as to solve at least one of the above-mentioned technical problems.

[0004] One aspect of the present invention provides a method for measuring the height of a high-maneuverability FTV for ground collision avoidance, the method comprising:

[0005] Select the current height of the drone relative to the ground , the current climb rate and ultrasonic measurement offset As a state variable;

[0006] Constructing a state quantity equation according to the state variables;

[0007] Construct measurement prediction equations;

[0008] According to the height relative to the ground at the current moment , the current climb rate and ultrasonic measurement offset Perform EKF filtering to obtain the altitude information of the flying drone.

[0009] Optionally, the state quantity equation is:

[0010] ;in,

[0011] is the state variable recursively calculated for the next moment, is the state transfer matrix, is the state variable at the current moment.

[0012] Optionally, the state transfer matrix It is expressed as follows:

[0013] ;in,

[0014] is a diagonal matrix, For time.

[0015] Optionally, the state variable recursively calculated at the next moment It is expressed as follows:

[0016] ;in,

[0017] is the recursive height for the next moment, is the recursive climbing rate for the next moment.

[0018] Optionally, the height of the next recursive step Obtained through the following formula:

[0019] ;in,

[0020] is the recursive climbing rate for the next moment, is the height of the drone relative to the ground, is the climb rate at the current moment, For time.

[0021] Optionally, the recursive climbing rate at the next moment is Obtained through the following formula:

[0022] ;in,

[0023] is the speed change of the aircraft in the inertial system, is the climb rate at the current moment, For time, is the attitude quaternion of the drone, It is the notation for a quaternion to rotate a vector.

[0024] Optionally, the measurement prediction equation includes:

[0025] ;in,

[0026] To measure the prediction equation, For measurement, It is the height after the ultrasonic measurement and GNSS position are fused. is the climb rate after the fusion of ultrasonic measurement and GNSS position.

[0027] Optionally, the quantity measured Obtained through the following formula:

[0028] ;in,

[0029] is the direction vector of the sensor's current distance measurement, projected in the inertial system, is the distance measured by the sensor, The installation position relative to the center of gravity is Offset in negative direction.

[0030] The present application also provides a height measurement device for ground collision avoidance of a FTV, and the height measurement device for ground collision avoidance of a FTV includes:

[0031] A selection module is used to select the relative height of the drone to the ground at the current moment. , the current climb rate and ultrasonic measurement offset As a state variable;

[0032] A state quantity equation building module, wherein the state quantity equation building module is used to build a state quantity equation according to the state variable;

[0033] A measurement prediction equation construction module, wherein the measurement prediction equation construction module is used to construct a measurement prediction equation;

[0034] A calculation module is used to obtain the relative height of the current moment to the ground , the current climb rate and ultrasonic measurement offset Perform EKF filtering to obtain the altitude information of the flying drone.

[0035] The present application also provides a ferry drone, the ferry drone comprising:

[0036] Steering gear;

[0037] An ultrasonic sensor, wherein the ultrasonic sensor is mounted on the steering gear;

[0038] A height measuring device for preventing a FTV from collision with the ground, wherein the height measuring device for preventing a FTV from collision with the ground is the height measuring device for preventing a FTV from collision with the ground described above.

[0039] Beneficial Effects

[0040] The height measurement method for ground collision avoidance of a FPV machine in the present application adopts a binary vector pointing measurement method. Even if the FPV machine has large attitude fluctuations during flight, the height above the ground can be effectively measured, thereby preventing ground collision and making the height above the ground controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of a method for measuring height of a FPV for ground collision avoidance according to an embodiment of the present application.

[0042] Figure 2 It is a schematic diagram of an electronic device for implementing a method for measuring height of a FTV for ground collision avoidance according to an embodiment of the present application.

[0043] Figure 3 This is a schematic diagram of the structure of the ultrasonic sensor of the FPV machine installed on the FPV machine.

[0044] Figure 4 It is a schematic diagram of test results of a method for measuring height of a FPV for ground collision avoidance according to an embodiment of the present application.

[0045] Reference numerals:

[0046] 1. Servo; 2. Steering wheel; 3. Ultrasonic sensor; 4. Servo connection part. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0048] Figure 1 It is a flow chart of a method for measuring height of a FPV for ground collision avoidance according to an embodiment of the present application.

[0049] like Figure 1 The height measurement method for avoiding collision between the ground and the aircraft shown includes:

[0050] Step 1: Select the current height of the drone relative to the ground , the current climb rate and ultrasonic measurement offset As a state variable;

[0051] Step 2: construct a state quantity equation according to the state variable;

[0052] Step 3: Construct the measurement prediction equation;

[0053] Step 4: According to the obtained height relative to the ground at the current moment , the current climb rate and ultrasonic measurement offset Perform EKF filtering to obtain the altitude information of the flying drone.

[0054] The height measurement method for ground collision avoidance of a FPV machine in the present application adopts a binary vector pointing measurement method. Even if the FPV machine has large attitude fluctuations during flight, the height above the ground can be effectively measured, thereby preventing ground collision and making the height above the ground controllable.

[0055] In this embodiment, the state quantity equation is:

[0056] ;in,

[0057] is the state variable recursively calculated for the next moment, is the state transfer matrix, is the state variable at the current moment.

[0058] In this embodiment, the state transfer matrix It is expressed as follows:

[0059] ;in,

[0060] It is a diagonal matrix.

[0061] In this embodiment, the state variable recursively deduced at the next moment is It is expressed as follows:

[0062] ;in,

[0063] is the recursive height for the next moment, is the recursive climbing rate for the next moment.

[0064] In this embodiment, the height recursively calculated at the next moment Obtained through the following formula:

[0065] ;in,

[0066] is the recursive climbing rate for the next moment, is the height of the drone relative to the ground, is the climb rate at the current moment, For time.

[0067] In this embodiment, the recursive climbing rate at the next moment is Obtained through the following formula:

[0068] ;in,

[0069] is the speed change of the aircraft in the inertial system, is the climb rate at the current moment, For time, is the attitude quaternion of the drone, It is the notation for a quaternion to rotate a vector.

[0070] In this embodiment, the measurement prediction equation includes:

[0071] ;in,

[0072] To measure the prediction equation, For measurement, It is the height after the ultrasonic measurement and GNSS position are fused. is the climb rate after the fusion of ultrasonic measurement and GNSS position.

[0073] In this embodiment, the quantity measured Obtained through the following formula:

[0074] ;in,

[0075] is the direction vector of the sensor's current distance measurement, projected in the inertial system, is the distance measured by the sensor, The installation position relative to the center of gravity is Offset in negative direction.

[0076] The present application is further described in detail below. It should be understood that this example does not constitute any limitation to the present application.

[0077] If you want to make the drone fly safely in the air and avoid collision with the ground, it is very important to measure the distance to the ground. The drone flies at a high speed, and the barometer may be affected by many factors and cause fluctuations. The barometer can only measure the altitude, but not the relative height to the ground at the current flight position. Therefore, it is necessary to introduce a distance measurement method that can measure the relative height.

[0078] Due to the large density difference between the ground and the air, a large proportion of sound waves will be reflected when they reach the interface between the ground and the air. Therefore, an ultrasonic sensor can be used to measure the distance from the drone to the ground. However, as mentioned earlier, the attitude deviation angle of the drone is very large during flight, and it is difficult to ensure that the measurement is within the effective angle range by simply placing the ultrasonic sensor at the bottom (the ultrasonic sensor generally measures within 15 degrees). Therefore, it is not possible to install the ultrasonic height sensor at the bottom of the fuselage to measure the distance from the drone to the ground like an ordinary multi-rotor.

[0079] Considering that the drone usually flies forward and backward at a large pitch angle, its roll angle is usually not large. We installed a directional ultrasonic sensor on a servo. And through a suitable algorithm, the servo sensor is always pointed in the vertical direction. In this way, no matter how the pitch angle of the drone changes, we can always measure the distance from the drone to the ground. The structural diagram of the device is shown below. Figure 3 As shown, in Figure 3 In the embodiment, the steering engine 1 is connected to the drone via the steering engine connection part 4, and the steering engine 1 is connected to the ultrasonic sensor 3 via the steering wheel.

[0080] In this embodiment, considering that the measured values ​​of the ultrasonic sensor may fluctuate occasionally in actual use, and the measurement frequency is also low (maximum 10HZ), the ultrasonic sensor data is fused with the airborne inertial sensor to improve the real-time and accuracy of the ground distance information acquisition. The EKF (Extended Kalman Filter) is used to fuse the data, and the selected state variables include the current height of the Flying Drone relative to the ground , the climb rate at the current moment , ultrasonic measurement offset caused by the height difference between the measurement plane and the absolute altitude . And assume is a parameter to be estimated that does not change recursively over time.

[0081] ;in,

[0082] is the state variable at the current moment, is the current height of the drone relative to the ground, is the climbing rate at the current moment, is the ultrasonic measurement offset caused by the height difference between the measurement plane and the absolute altitude. In this embodiment, is a parameter to be estimated that does not change recursively over time.

[0083] In this embodiment, the speed change of the aircraft in the inertial system is , can be measured using an onboard accelerometer. It is the acceleration measured by the inertial sensor. This is the specific force including gravity, so the gravity acceleration also needs to be eliminated. is the attitude quaternion of the drone, where is the real part of the quaternion, and the other three are the imaginary parts. The time derivative of the velocity of the drone in the body axis system is:

[0084] ;in,

[0085] is the speed change of the aircraft in the inertial system.

[0086] Next moment climb rate Should be:

[0087] ;

[0088] in,

[0089] is the speed change of the aircraft in the inertial system, is the climb rate at the current moment, For time, is the attitude quaternion of the drone, is the notation for the rotation of a vector by a quaternion, is the time interval.

[0090] The height at the next moment can be described by trapezoidal integral:

[0091] ;in,

[0092] is the recursive climbing rate for the next moment, is the height of the drone relative to the ground, is the climb rate at the current moment, For time.

[0093] In the inertial system, according to the data measured by the inertial sensor, the recursive state at the next moment is expressed as :

[0094] ;in,

[0095] is the recursive height for the next moment, is the recursive climbing rate for the next moment, Deflection for ultrasonic measurements.

[0096] In this embodiment, the state transfer matrix It is expressed as follows:

[0097] ;in,

[0098] is a diagonal matrix, For time.

[0099] In order to make the ultrasonic sensor point in the vertical direction as much as possible, the following servo angle control strategy is adopted. The projection of the z-axis under the body axis in the inertial system can be expressed as:

[0100] ;

[0101] The actual angle between the current body x-axis and the inertial system z-axis is It can be expressed as:

[0102] ;

[0103] in, is the arc cosine. This allows us to define a rotation quaternion , describes the rotation of the body x from the current state to the vertical state. Since the ultrasonic sensor can only rotate along the y-axis of the body, when the ultrasonic sensor rotates along the y-axis of the body, the angle between it and the z-axis, that is, the rotation angle, is defined as :

[0104] ;in,

[0105] is the rotation angle, is the rotation quaternion, It is the actual angle between the current body x-axis and the inertial system z-axis.

[0106] Next, due to the random body rotation characteristics of the ultrasonic sensor, and the negative x-direction offset of the installation position relative to the center of gravity The measured height information needs to be solved. It is a sign operation, the purpose of which is to avoid the bijection phenomenon of quaternion, which causes the problem of rotating in the direction with the larger angle.

[0107] Assume that the current inertial system position of the drone is The position of the ultrasonic sensor's measuring unit in the inertial system is express.

[0108] ;in,

[0109] is the position of the ultrasonic sensor's measurement unit in the inertial system, is the attitude quaternion of the drone, The installation position is offset in the negative x direction relative to the center of gravity.

[0110] The direction vector of the distance currently measured by the sensor is projected in the inertial system. It is expressed as:

[0111] ;

[0112] The vector ultrasonic height sensor measures the distance from the installation location to the center of gravity, and eliminates the influence of the pitch angle as much as possible. Define a slope , then the distance measured by the sensor for:

[0113] ;

[0114] ;

[0115] Thus, when using this binary vector ultrasonic sensor to measure height, the measurement for:

[0116] ;

[0117] In addition, in order to improve the stability of positioning, the height from the fusion with GNSS position and climb rate Incorporate fusion to construct measurement vector for:

[0118] ;in,

[0119] To measure the prediction equation, For measurement, It is the height after the ultrasonic measurement and GNSS position are fused. is the climb rate after the fusion of ultrasonic measurement and GNSS position.

[0120] Other expressions for the recursive EKF are as follows. The measurement matrix H is defined as:

[0121] Sensor height measurement , measurement matrix , the measurement vector , the superscript refers to At this moment, the height of the drone relative to the ground is the state vector of the drone, the rotation angle of the ultrasonic unit .

[0122] ;

[0123] .

[0124] partial differential It refers to the Jacobian matrix of the measurement vector to the state quantity.

[0125] partial differential Refers to the partial derivative of the sensor altitude measurement with respect to the actual altitude above the ground.

[0126] A priori estimate of the covariance matrix of the next state estimate for:

[0127] ;

[0128] Kalman Gain , is the sensor noise covariance matrix:

[0129] ;

[0130] is the observation function, which represents the state vector Convert to observation vector The expected value of the next moment and the covariance matrix for:

[0131] ;

[0132] ;

[0133] In this embodiment, according to the height relative to the ground at the current moment, , the current climb rate and ultrasonic measurement offset The following method can be used to perform EKF filtering to obtain the altitude information of the flying machine:

[0134] Step 41: Predict the state through the state equation;

[0135] Step 42: Then perform state error covariance matrix prediction;

[0136] Step 43: Calculate the filter gain;

[0137] Step 44: Update the state error covariance matrix;

[0138] Step 45: Perform data fusion and update the status.

[0139] The above completes the altitude estimation of the drone. Considering the frequency difference of different sensors, when there is no ultrasonic sensor data update, only the prediction step is performed, and when there is sensor data update, the measurement update is performed.

[0140] Similarly, see Figure 4 We verify the results of data fusion in motion capture. We focus on testing the results of high-degree fusion of the drone at different pitch angles. Figure 4 As shown in the figure. Due to the drift characteristics of the barometer measurement itself, the altitude data without absolute altitude correction drifts farther and farther over time. However, with the vector ultrasonic altimeter, the drone can still accurately measure the altitude even if the pitch attitude changes greatly.

[0141] Thus, we can obtain the measurement of the height of the drone relative to the ground, so that the drone has the ability to control its height relative to the ground. The conventional two-loop PID can be used to maintain the height.

[0142] In the prior art, the existing height measurement solutions include barometer, laser altimeter, ultrasonic altimeter, lidar, GNSS, UWB, pure vision, etc. Among them, UWB requires the establishment of a base station, which is not convenient to deploy. GNSS has the problems of low frequency, no terrain information, and easy interference. Lidar has large weight and power consumption, and its low frequency makes it difficult to meet the real-time requirements. Laser altimeter cannot be used on the water surface. Barometers are not convenient to use on some waterproof aircraft because the aircraft may have a closed cabin with poor air circulation, and like GNSS, it is global positioning and lacks information on the height above the ground. Pure vision is easily affected by ambient light. Although ordinary ultrasonic waves can measure the distance to the ground, there is a problem of high requirements for the attitude of the drone. For highly maneuverable cross-country aircraft, the attitude changes violently, and a high real-time, anti-interference, and accurate anti-collision height measurement device is required.

[0143] This application can solve the above problems, as follows:

[0144] 1. This application does not require the establishment of a base station. It only requires the installation of an ultrasonic sensor on the servo, and then the altitude information of the FPV can be obtained through the method of this application.

[0145] 2. The height measurement method for ground collision avoidance of a FPV drone in the present application is not easily interfered with. Even if the FPV drone has large attitude fluctuations during flight, the height above the ground can be effectively measured, thereby preventing ground collisions and making the height above the ground controllable.

[0146] 3. This application uses an ultrasonic sensor, and there will be no problem that the laser altimeter cannot be used on the water surface.

[0147] 4. This application does not need to consider the issue that pure vision is easily affected by ambient light.

[0148] The present application also provides a height measurement device for ground collision avoidance of a FTV, and the height measurement device for ground collision avoidance of a FTV comprises a selection module, a state quantity equation construction module, a measurement prediction equation construction module and a calculation module, wherein:

[0149] The selection module is used to select the current height of the drone relative to the ground. , the current climb rate and ultrasonic measurement offset As a state variable;

[0150] The state quantity equation construction module is used to construct the state quantity equation according to the state variable;

[0151] The measurement prediction equation construction module is used to construct the measurement prediction equation;

[0152] The calculation module is used to obtain the relative height of the ground at the current moment , the current climb rate and ultrasonic measurement offset The following method can be used to perform EKF filtering to obtain the altitude information of the flying machine:

[0153] Step 41: Predict the state through the state equation;

[0154] Step 42: Then perform state error covariance matrix prediction;

[0155] Step 43: Calculate the filter gain;

[0156] Step 44: Update the state error covariance matrix;

[0157] Step 45: Perform data fusion and update the status.

[0158] The above completes the altitude estimation of the drone. Considering the frequency difference of different sensors, when there is no ultrasonic sensor data update, only the prediction step is performed, and when there is sensor data update, the measurement update is performed.

[0159] Similarly, see Figure 4 We verify the results of data fusion in motion capture. We focus on testing the results of high-degree fusion of the drone at different pitch angles. Figure 4 As shown in the figure. Due to the drift characteristics of the barometer measurement itself, the altitude data without absolute altitude correction drifts farther and farther over time. However, with the vector ultrasonic altimeter, the drone can still accurately measure the altitude even if the pitch attitude changes greatly.

[0160] Thus, we can obtain the measurement of the height of the drone relative to the ground, so that the drone has the ability to control its height relative to the ground. The conventional two-loop PID can be used to maintain the height.

[0161] In the prior art, the existing height measurement solutions include barometer, laser altimeter, ultrasonic altimeter, lidar, GNSS, UWB, pure vision, etc. Among them, UWB requires the establishment of a base station, which is not convenient to deploy. GNSS has the problems of low frequency, no terrain information, and easy interference. Lidar has large weight and power consumption, and its low frequency makes it difficult to meet the real-time requirements. Laser altimeter cannot be used on the water surface. Barometers are not convenient to use on some waterproof aircraft because the aircraft may have a closed cabin with poor air circulation, and like GNSS, it is global positioning and lacks information on the height above the ground. Pure vision is easily affected by ambient light. Although ordinary ultrasonic waves can measure the distance to the ground, there is a problem of high requirements for the attitude of the drone. For highly maneuverable cross-country aircraft, the attitude changes violently, and a high real-time, anti-interference, and accurate anti-collision height measurement device is required.

[0162] This application can solve the above problems, as follows:

[0163] 1. This application does not require the establishment of a base station. It only requires the installation of an ultrasonic sensor on the servo, and then the altitude information of the FPV can be obtained through the method of this application.

[0164] 2. The height measurement method for ground collision avoidance of a FPV drone in the present application is not easily interfered with. Even if the FPV drone has large attitude fluctuations during flight, the height above the ground can be effectively measured, thereby preventing ground collisions and making the height above the ground controllable.

[0165] 3. This application uses an ultrasonic sensor, and there will be no problem that the laser altimeter cannot be used on the water surface.

[0166] 4. This application does not need to consider the issue that pure vision is easily affected by ambient light.

[0167] The present application also provides a height measurement device for ground collision avoidance of a FTV, and the height measurement device for ground collision avoidance of a FTV comprises a selection module, a state quantity equation construction module, a measurement prediction equation construction module and a calculation module, wherein:

[0168] The selection module is used to select the current height of the drone relative to the ground. , the current climb rate and ultrasonic measurement offset As a state variable;

[0169] The state quantity equation construction module is used to construct the state quantity equation according to the state variable;

[0170] The measurement prediction equation construction module is used to construct the measurement prediction equation;

[0171] The calculation module is used to obtain the relative height of the ground at the current moment , the current climb rate and ultrasonic measurement offset Perform EKF filtering to obtain the altitude information of the flying drone.

[0172] See also Figure 3 The present application also provides a FTV, which includes a steering engine 1, an ultrasonic sensor 3, and a height measurement device for preventing the FTV from collision with the ground, wherein:

[0173] The steering gear 1 is connected to the drone via the steering gear connection part 4, and the steering gear 1 is connected to the ultrasonic sensor 3 via the steering wheel;

[0174] The height measuring device for ground collision avoidance of a FTV is the height measuring device for ground collision avoidance of a FTV as described above.

[0175] See also Figure 4 We verify the results of data fusion in a motion capture system (a measurement device based on visual analysis of motion state, which can measure position with sub-millimeter accuracy). We focus on testing the results of high-degree fusion of the drone at different pitch angles. Test results of high-degree data fusion. The drone used in the test is an ordinary multi-rotor drone with a Figure 3 The device shown in the figure has a sealed cabin for waterproofing purposes. Since the drone's air pressure sensor is sealed and lacks absolute altitude correction, the altitude data analyzed by the open source flight control drifts farther and farther over time. However, with the ultrasonic sensor 3, even if the pitch attitude changes significantly, the drone can still accurately measure the altitude through the method of this application. The result is Figure 4 shown.

[0176] It should be noted that the above explanations of the method embodiment are also applicable to the system of this embodiment and will not be repeated here.

[0177] The present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the computer program, the above-mentioned height measurement method for ground collision avoidance of a through-the-aircraft is implemented.

[0178] The present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it can implement the above-mentioned height measurement method for ground collision avoidance of a through-the-aircraft.

[0179] Figure 2 It is an exemplary structural diagram of an electronic device capable of implementing a method for measuring the height of a Flying Vehicle for ground collision avoidance provided according to an embodiment of the present application.

[0180] like Figure 2 As shown, the electronic device includes an input device 501, an input interface 502, a central processor 503, a memory 504, an output interface 505, and an output device 506. The input interface 502, the central processor 503, the memory 504, and the output interface 505 are interconnected through a bus 507, and the input device 501 and the output device 506 are connected to the bus 507 through the input interface 502 and the output interface 505, respectively, and then connected to other components of the electronic device. Specifically, the input device 501 receives input information from the outside, and transmits the input information to the central processor 503 through the input interface 502; the central processor 503 processes the input information based on the computer executable instructions stored in the memory 504 to generate output information, temporarily or permanently stores the output information in the memory 504, and then transmits the output information to the output device 506 through the output interface 505; the output device 506 outputs the output information to the outside of the electronic device for use by the user.

[0181] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0182] In addition, it is obvious that the word "comprising" does not exclude other units or steps. The multiple units, modules or systems stated in the system claims can also be implemented by one unit or the overall system through software or hardware.

[0183] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for measuring the height of a Flying Vehicle for ground collision avoidance, characterized in that: The height measurement method for ground collision avoidance of a FTV includes: Select the current height of the drone relative to the ground , the current climb rate and ultrasonic measurement offset As a state variable; Constructing a state quantity equation according to the state variables; Construct measurement prediction equations; According to the height relative to the ground at the current moment , the current climb rate and ultrasonic measurement offset Perform EKF filtering to obtain the altitude information of the flying machine; The state equation is: ;in, is the state variable recursively calculated for the next moment, is the state transfer matrix, is the state variable at the current moment The state transition matrix It is expressed as follows: ;in, is a diagonal matrix, For time, is the time interval; The next moment recursive state variable It is expressed as follows: ;in, is the recursive height for the next moment, is the recursive climbing rate for the next moment, Deflection measurement for ultrasonic waves; The height of the next recursive moment Obtained through the following formula: ;in, is the recursive climbing rate for the next moment, is the height of the drone relative to the ground, is the climb rate at the current moment, For time, is the time interval.

2. The method for measuring the height of a FTV for ground collision avoidance as claimed in claim 1, characterized in that: The recursive climbing rate at the next moment Obtained through the following formula: ;in, is the speed change of the aircraft in the inertial system, is the climb rate at the current moment, For time, is the attitude quaternion of the drone, is the notation for the rotation of a vector by a quaternion, is the time interval.

3. The method for measuring the height of a FTV for ground collision avoidance as claimed in claim 2, characterized in that: The measurement prediction equation includes: ;in, To measure the prediction equation, For measurement, It is the height after the ultrasonic measurement and GNSS position are fused. is the climb rate after the fusion of ultrasonic measurement and GNSS position.

4. The method for measuring the height of a FTV for ground collision avoidance as claimed in claim 3, characterized in that: The quantity measured Obtained through the following formula: ;in, is the direction vector of the sensor's current distance measurement, projected in the inertial system, is the distance measured by the sensor, The installation position relative to the center of gravity is Offset in negative direction.

5. A height measurement device for ground collision avoidance of a FTV, characterized in that: The height measuring device for ground collision prevention of a FTV includes: A selection module is used to select the relative height of the drone to the ground at the current moment. , the current climb rate and ultrasonic measurement offset As a state variable; A state quantity equation building module, wherein the state quantity equation building module is used to build a state quantity equation according to the state variable; A measurement prediction equation construction module, wherein the measurement prediction equation construction module is used to construct a measurement prediction equation; A calculation module is used to obtain the relative height of the current moment to the ground , the current climb rate and ultrasonic measurement offset Perform EKF filtering to obtain the altitude information of the flying machine; The state equation is: ;in, is the state variable recursively calculated for the next moment, is the state transfer matrix, is the state variable at the current moment The state transition matrix It is expressed as follows: ;in, is a diagonal matrix, For time; The next moment recursive state variable It is expressed as follows: ;in, is the recursive height for the next moment, is the recursive climbing rate for the next moment, Deflection measurement for ultrasonic waves; The height of the next recursive moment Obtained through the following formula: ;in, is the recursive climbing rate for the next moment, is the height of the drone relative to the ground, is the climb rate at the current moment, For time, is the time interval.

6. A flying drone, characterized in that: The traversing machine comprises: Steering gear; An ultrasonic sensor, wherein the ultrasonic sensor is mounted on the steering gear; A height measuring device for preventing a FTV from collision with the ground, wherein the height measuring device for preventing a FTV from collision with the ground is the height measuring device for preventing a FTV from collision with the ground as claimed in claim 5.

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