A method and system for sensing external airspeed during flight

Abstract

The present invention relates to a method and system for sensing external airspeed during flight. The present invention uses a pressure sensor to obtain the maximum pressure and minimum pressure at the flapping damping of the propeller hub, and after obtaining the airspeed through blade force analysis, the airspeed information can be obtained without adding a pitot tube, thereby improving the control accuracy of the unmanned aerial vehicle. Compared with installing a pitot tube, the pitot tube can avoid malfunctioning due to icing and other phenomena at high altitudes.

Description

Technical Field

[0001] The present invention relates to the field of airspeed sensing technology, and in particular to a method and system for sensing external airspeed during flight by utilizing helicopter rotor flapping damping pressure. Background Art

[0002] Conventional unmanned helicopters need to collect the relative air speed outside the rotor diameter and outside the rotor vortex ring to obtain the external relative air speed relative to the flight direction during flight, which has always been a big problem in the application of unmanned helicopters. Many unmanned helicopters use GPS speed as a reference for flight speed. Since GPS speed represents the speed relative to the ground, commonly known as "ground speed", this has a greater impact on flight operations under unstable wind speeds. For example, when an unmanned helicopter is hovering against the wind, the flight speed sensed by the flight control computer with reference to the GPS positioning speed is 0, but under the condition of hovering against the wind, the helicopter needs to make a "forward flight" action to offset the influence of wind speed and stay in place, which requires the unmanned helicopter to sense the relative air speed in the flight direction, commonly known as "airspeed". The traditional airspeed measurement method is to install a forward-facing pitot tube on the aircraft. The principle of the pitot tube measuring the aircraft speed is that when the aircraft flies forward, the airflow rushes into the pitot tube, and the sensor at the end of the tube will feel the impact force of the airflow, that is, the dynamic pressure. The faster the aircraft flies, the greater the dynamic pressure. If you compare the static pressure and dynamic pressure when the air is still, you can tell how fast the incoming air is, that is, how fast the plane is flying.

[0003] The existing means of sensing external airspeed is generally based on the installation of a dedicated helicopter pitot tube for sensing. Affected by factors such as gravity, the external airspeed perception of unmanned helicopters during flight becomes inaccurate. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for sensing the external airspeed during flight by using the flapping damping pressure of a helicopter rotor. The method and system can accurately measure the external airspeed of an unmanned helicopter during flight without separately installing a dedicated helicopter airspeed tube, so as to provide effective data guarantee for precise navigation and coordinated control, thereby being able to control and reduce weight and greatly reduce the packaging volume during transportation.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method of sensing external airspeed while flying, comprising:

[0007] A pressure sensor is used to obtain the maximum pressure and minimum pressure at the hub flapping damping point;

[0008] determining a maximum speed of the blade relative to the air based on the maximum pressure;

[0009] determining a minimum speed of the blade relative to the air based on the minimum pressure;

[0010] determining a relative air speed of the helicopter when flying based on the maximum speed and the minimum speed;

[0011] External airspeed information while in flight is determined based on the relative air speed.

[0012] Preferably, determining the maximum speed of the blade relative to the air according to the maximum pressure specifically includes:

[0013] The maximum speed of the blade relative to the air is determined based on the maximum pressure using the lift equation.

[0014] Preferably, the pressure sensor is installed at a hub flapping damper of the helicopter.

[0015] Preferably, determining the minimum speed of the blade relative to the air according to the minimum pressure specifically includes:

[0016] The lift equation is used to determine the minimum speed of the blade relative to the air based on the minimum pressure.

[0017] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0018] The method for sensing the external airspeed during flight provided by the present invention uses a pressure sensor to obtain the maximum pressure and the minimum pressure at the flapping damping of the propeller hub, and after obtaining the airspeed through blade force analysis, the airspeed information can be obtained without adding a pitot tube, thereby improving the control accuracy of the UAV. Compared with installing a pitot tube, it can avoid problems such as failure of the pitot tube caused by icing at high altitude.

[0019] Corresponding to the method for sensing external airspeed during flight provided above, the present invention also provides a system for sensing external airspeed during flight, the system comprising:

[0020] A pressure acquisition module, used to acquire the maximum pressure and the minimum pressure at the hub flapping damping position by using a pressure sensor; the pressure sensor is installed at the hub flapping damping position of the helicopter;

[0021] A first speed determination module, configured to determine a maximum speed of the blade relative to the air according to the maximum pressure;

[0022] A second speed determination module, configured to determine a minimum speed of the blade relative to the air according to the minimum pressure;

[0023] An air speed determination module, used for determining the relative air speed of the helicopter when flying according to the maximum speed and the minimum speed;

[0024] The airspeed information determination module is used to determine the external airspeed information during flight based on the relative air speed.

[0025] Preferably, the first speed determination module comprises:

[0026] The first speed determination unit is used to determine the maximum speed of the blade relative to the air according to the maximum pressure by using a lift equation.

[0027] Preferably, the second speed determination module comprises:

[0028] The second speed determination unit is used to determine the minimum speed of the blade relative to the air according to the minimum pressure by using a lift equation.

[0029] Since the technical effect achieved by the system for sensing external airspeed during flight provided by the present invention is the same as the technical effect achieved by the method for sensing external airspeed during flight provided above, it will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A flow chart of a method for sensing external airspeed during flight using helicopter rotor flapping damping pressure provided by the present invention;

[0032] Figure 2 A schematic diagram of the flight speed of a helicopter provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of the system structure for sensing the external airspeed during flight using the helicopter rotor flapping damping pressure provided by the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The purpose of the present invention is to provide a method and system for sensing the external airspeed during flight by using the flapping damping pressure of a helicopter rotor. The method and system can accurately measure the external airspeed of an unmanned helicopter during flight without separately installing a dedicated helicopter airspeed tube, so as to provide effective data guarantee for precise navigation and coordinated control, thereby being able to control and reduce weight and greatly reduce the packaging volume during transportation.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1 As shown, the method for sensing external airspeed during flight provided by the present invention comprises:

[0038] Step 100: Use a pressure sensor to obtain the maximum pressure and the minimum pressure at the hub flapping damping. The pressure sensor is installed at the hub flapping damping of the helicopter.

[0039] Step 101: Determine the maximum speed of the blade relative to the air according to the maximum pressure.

[0040] Step 102: Determine the minimum speed of the blade relative to the air according to the minimum pressure.

[0041] Step 103: Determine the relative air speed of the helicopter when flying according to the maximum speed and the minimum speed.

[0042] Step 104: Determine external airspeed information during flight based on the relative air speed.

[0043] The following is combined with Figure 2 The flight speed shown is described below. Based on the implementation principle, the specific implementation process of the method for sensing the external airspeed during flight provided above is described. Figure 2 V1 in the equation is the air speed of the forward propeller, V1 = V 旋 +V 前 , V2 is the speed of the backward propeller against the air, V2=V 旋 -V 前 , V 旋 is the blade rotation speed, V 前 is the forward speed of the helicopter.

[0044] The lift difference generated by the "forward" rotor and the "rearward" rotor of the helicopter rotor when rotating is combined with the external lift difference to calculate the air speed of the external air relative to the flight direction of the unmanned helicopter, so as to provide "airspeed" data reference for the UAV helicopter flight control system.

[0045] When the unmanned helicopter flies forward horizontally, the speed of the right blade moving forward relative to the air is greater than that of the left blade moving backward. Therefore, according to the lift equation It can be seen that the forward-moving blade generates a greater lift than the backward-moving blade. Where y represents lift, ρ represents air density, v represents blade speed, s represents lift area (i.e. blade area), c y represents the lift coefficient, c y is a constant in the formula and is related to the blade airfoil.

[0046] The blades with large lift under the flapping structure of the hub will produce greater pressure on the flapping damping. When the blades move backward, the lift decreases, so the pressure on the flapping damping decreases. Generally, the hub is the connecting piece between the two blades. There is a flapping mechanism at the connection between the main rotor and the hub. When the main rotor blades are subjected to lift, they will flap upward. At this time, the sensor placed in the damping behind the flapping structure can read the damping force and obtain the rotor lift.

[0047] The sensor is connected to the damper. When the flapping structure is stressed, the flapping structure is lifted up, the damper is deformed, and the pressure sensor placed behind the damper reads the force information. The damper directly bears the force of the flapping structure's upward movement. The pressure sensor can be attached to any part of the damper that is deformed, and the relationship between the damping deformation and the main rotor force can be obtained.

[0048] The helicopter has a flight controller. The pressure sensor collects the maximum and minimum pressures of each revolution and transmits them to the flight controller for calculation to obtain the airspeed.

[0049] When the unmanned helicopter is flying forward, the maximum pressure generated by the flapping damping is the maximum lift generated by the blades when moving forward. At this time, the speed of the blades relative to the air is the speed of the blades themselves plus the speed of the unmanned helicopter relative to the air when flying forward. The minimum pressure generated by the flapping damping is the minimum lift generated by the blades when moving backward. At this time, the speed of the blades relative to the air is the speed of the blades themselves minus the speed of the unmanned helicopter relative to the air when flying forward.

[0050] Based on the above analysis, a pressure sensor is installed at the hub flapping damping position. The difference between the maximum pressure and the minimum pressure obtained by the pressure sensor is the difference between the maximum lift and the minimum lift of the blade. The relative air speed of the blade can be calculated according to the lift equation: Then, the difference between the maximum speed and the minimum speed is the speed of the unmanned helicopter relative to the air when it flies forward: v 空气 =v 最大 -v 最小 Among them, the flight control can know the number of rotor revolutions and rotation conditions by using a pressure sensor to collect the maximum and minimum pressures in each circle. Generally, the maximum and minimum pressure positions are the leftmost and rightmost points when the rotor rotates.

[0051] In the present invention, since the airspeed sensing device is the data obtained by calculation of the pressure sensor, compared with the traditional pitot tube, there is no airspeed sensor error caused by the pitot tube blockage, pitot tube icing and other weather conditions. No manual external inspection is required. The computer automatically reads the calibration data when starting.

[0052] In addition, the present invention is based on the method of sensing the external airspeed during flight by using the flapping damping pressure of the helicopter rotor, and can obtain real-time external airspeed data. After obtaining the airspeed through blade force analysis, the airspeed information can be obtained without adding a pitot tube (most helicopters are not equipped with a pitot tube), thereby improving the control accuracy of the drone. Compared with installing a pitot tube, it also avoids problems such as failure of the pitot tube caused by icing at high altitudes.

[0053] Corresponding to the above-mentioned method for sensing external airspeed during flight, the present invention also provides a system for sensing external airspeed during flight, such as Figure 3 As shown, the system includes:

[0054] The pressure acquisition module 1 is used to acquire the maximum pressure and the minimum pressure at the hub flapping damping position by using a pressure sensor. The pressure sensor is installed at the hub flapping damping position of the helicopter.

[0055] The first speed determination module 2 is used to determine the maximum speed of the blade relative to the air according to the maximum pressure.

[0056] The second speed determination module 3 is used to determine the minimum speed of the blade relative to the air according to the minimum pressure.

[0057] The air speed determination module 4 is used to determine the relative air speed of the helicopter during flight according to the maximum speed and the minimum speed.

[0058] The airspeed information determination module 5 is used to determine the external airspeed information during flight based on the relative air speed.

[0059] As a preferred embodiment of the present invention, the first speed determination module 2 provided above includes:

[0060] The first speed determination unit is used to determine the maximum speed of the blade relative to the air according to the maximum pressure by using the lift equation.

[0061] As another preferred embodiment of the present invention, the second speed determination module 3 provided above includes:

[0062] The second speed determination unit is used to determine the minimum speed of the blade relative to the air according to the minimum pressure by using the lift equation.

[0063] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0064] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for sensing external airspeed during flight, characterized in that: include: A pressure sensor is used to obtain the maximum pressure and minimum pressure at the hub flapping damping point; determining a maximum speed of the blade relative to the air based on the maximum pressure; determining a minimum speed of the blade relative to the air based on the minimum pressure; determining a relative air speed of the helicopter when flying based on the maximum speed and the minimum speed; External airspeed information while in flight is determined based on the relative air speed.

2. The method for sensing external airspeed during flight according to claim 1, characterized in that: Determining the maximum speed of the blade relative to the air according to the maximum pressure specifically includes: The maximum speed of the blade relative to the air is determined based on the maximum pressure using the lift equation.

3. The method for sensing external airspeed during flight according to claim 1, characterized in that: The pressure sensor is installed at the rotor hub flapping damping of the helicopter.

4. The method for sensing external airspeed during flight according to claim 1, characterized in that: Determining the minimum speed of the blade relative to the air according to the minimum pressure specifically includes: The lift equation is used to determine the minimum speed of the blade relative to the air based on the minimum pressure.

5. A system for sensing external airspeed during flight, characterized in that: include: A pressure acquisition module, used to obtain the maximum pressure and the minimum pressure at the hub flapping damping point using a pressure sensor; The pressure sensor is installed at the rotor hub flapping damping of the helicopter; A first speed determination module, configured to determine a maximum speed of the blade relative to the air according to the maximum pressure; A second speed determination module, configured to determine a minimum speed of the blade relative to the air according to the minimum pressure; An air speed determination module, used for determining the relative air speed of the helicopter when flying according to the maximum speed and the minimum speed; The airspeed information determination module is used to determine the external airspeed information during flight based on the relative air speed.

6. The system for sensing external airspeed during flight according to claim 5, characterized in that: The first speed determination module comprises: The first speed determination unit is used to determine the maximum speed of the blade relative to the air according to the maximum pressure by using a lift equation.

7. The system for sensing external airspeed during flight according to claim 5, characterized in that: The second speed determination module comprises: The second speed determination unit is used to determine the minimum speed of the blade relative to the air according to the minimum pressure by using a lift equation.

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