Helicopter tail rotor rotating speed control method, device, equipment and medium

Abstract

The invention belongs to the technical field of helicopter control, and particularly discloses a helicopter tail rotor rotating speed control method, device and equipment and a medium. Determining the operation stage of the helicopter according to the position information, wherein the operation stage comprises a ground starting stage and an air flight stage; regulating and controlling the rotating speed of the tail rotor according to the operation stage; wherein when the operation stage is a ground starting stage, closed-loop control is performed on the rotating speed of the tail rotor, so that the rotating speed of the tail rotor is kept away from a first preset range when the helicopter is stable; when the operation stage is the air flight stage, the tail rotor rotating speed is kept away from a second preset range. The problem that the helicopter rotates on the ground and the vibration level of the tail beam is too high is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of helicopter control, and particularly relates to a method, device, equipment and medium for controlling the rotational speed of a helicopter tail rotor. Background Art

[0002] With the accelerating development of intelligent and unmanned technologies, electric unmanned helicopters have shown great potential in multiple fields. Traditional fuel helicopters have problems such as high fuel consumption, high noise, and high maintenance costs. Electric unmanned helicopters, with their advantages of environmental protection, high efficiency, and low cost, have become an important direction for future aviation development. Especially in the fields of logistics, agriculture, and emergency, the market has an urgent demand for efficient, flexible, and low-cost unmanned aerial vehicles.

[0003] However, the traditional helicopter tail rotor control method uses mechanical transmission + variable collective control. However, this control method relies on a complex mechanical structure. In the prior art, a tail rotor control scheme using direct drive by an electric motor is proposed, and the thrust is controlled by adjusting the rotational speed of the tail rotor, and then the torque of the main rotor of the helicopter is balanced. However, this new scheme also brings new problems. The main rotor and the tail rotor are independently controlled. When starting on the ground, the torques formed by the rotation of the main rotor and the tail rotor do not match, often causing the helicopter to spin in place on the ground. In addition, when the tail rotor is used for yaw control, due to the large rotational speed adjustment range, the vibration of the tail boom is relatively large during the rotational speed adjustment process, which will also affect the flight state of the helicopter. Summary of the Invention

[0004] The purpose of the present invention is to provide a method, device, equipment and medium for controlling the rotational speed of a helicopter tail rotor to solve the problems of the helicopter spinning on the ground and the excessive vibration level of the tail boom.

[0005] To achieve the above purpose, the present invention is implemented by adopting the following technical solutions: According to one aspect of the present invention, a method for controlling the rotational speed of a helicopter tail rotor is provided, including the following steps: Obtain the position information of the helicopter; Determine the operation stage of the helicopter according to the position information, and the operation stage includes a ground start stage and an in-air flight stage; Regulate the rotational speed of the tail rotor according to the operation stage; wherein, when the operation stage is the ground start stage, perform closed-loop control on the rotational speed of the tail rotor to avoid the first preset range for the rotational speed of the tail rotor when the helicopter is stable; when the operation stage is the in-air flight stage, avoid the second preset range.

[0006] The first preset range is the preset range in which resonance occurs between the tail rotor and the tail boom during the ground start stage; the second preset range is the preset range in which resonance occurs between the tail rotor and the tail boom during the in-air flight stage.

[0007] "When the helicopter is stable" means that the main rotor speed and the tail rotor speed reach the preset idle speed or ground operation value, and the fluctuation range is within the allowable threshold. Generally, the allowable threshold is ±(3 - 5)%.

[0008] The main rotor and the tail rotor of the helicopter are independently controlled. Adopting the above technical solution can avoid the helicopter from spinning in place due to the torque mismatch formed by the rotation of the main rotor and the tail rotor during the ground startup phase, effectively reduce the vibration level of the helicopter's tail boom during the air flight phase, reduce the displacement of the end of the tail boom, and improve the structural stability.

[0009] According to an embodiment of the present invention, when the operation phase is the ground startup phase, the steps of performing closed-loop control on the tail rotor speed to avoid the tail rotor speed at the stable state of the helicopter from falling within the first preset range include: Obtain the current main rotor speed and tail rotor speed; Based on the current main rotor speed and tail rotor speed, obtain the adjustment amount of the tail rotor speed based on the linear relationship between the tail rotor speed and the main rotor speed; Adjust the tail rotor speed according to the adjustment amount of the tail rotor speed, so that the tail rotor speed at the stable state of the helicopter avoids the first preset range.

[0010] Furthermore, the linear relationship between the tail rotor speed and the main rotor speed is as follows: ; In the formula, k 1 is the correlation coefficient, Ω t is the tail rotor speed; Ω m is the main rotor speed.

[0011] Among them, the initial value of the correlation coefficient k 1 can be calculated according to the following formula: ; In the formula, C P is the main rotor power coefficient; R m is the main rotor radius; C t is the tail rotor thrust coefficient; R t is the tail rotor radius; L is the distance between the thrust axis or the pull axis of the helicopter's tail rotor and the main rotor axis.

[0012] Furthermore, algorithms such as PID control, PI control, and adaptive control are used to implement the closed-loop control of the tail rotor speed.

[0013] Therefore, during the ground start-up phase, the tail rotor speed is controlled and adjusted based on the linear relationship between the tail rotor speed and the main rotor speed, effectively solving the problem of the helicopter spinning in place during the ground start-up phase caused by insufficient ground static friction and mismatched rotational torques between the main rotor and the tail rotor.

[0014] Closed-loop control of the tail rotor speed and the main rotor speed during the ground start-up phase effectively solves the attitude control problem caused by the independent electric drive control of the main rotor and the tail rotor, making the helicopter attitude control smoother.

[0015] According to an embodiment of the present invention, the first preset range is in the range of 0.5 - 1.5 times the nth-order natural frequency of the tail boom.

[0016] Preferably, the first preset range is in the range of 0.7 - 1.3 times the nth-order natural frequency of the tail boom.

[0017] According to an embodiment of the present invention, when the helicopter is in the air flight phase, the flight state is determined based on the position information and attitude angle information of the helicopter; the interval width of the second preset range is adjusted according to the flight state; The flight states include a hover state, a cruise state, a normal yaw state, and an extreme yaw state.

[0018] According to an embodiment of the present invention, when the helicopter is in the hover state, the second preset range is in the range of 0.5 - 1.5 times the nth-order natural frequency of the tail boom; when the helicopter is in the cruise state, the second preset range is in the range of 0.7 - 1.3 times the nth-order natural frequency of the tail boom; when the helicopter is in the normal yaw state, the second preset range is in the range of 0.7 - 1.3 times the nth-order natural frequency of the tail boom; when the helicopter is in the extreme yaw state, the second preset range is in the range of 0.8 - 1.2 times the nth-order natural frequency of the tail boom.

[0019] Preferably, when the helicopter is in the hover state, the second preset range is in the range of 0.7 - 1.3 times the nth-order natural frequency of the tail boom; when the helicopter is in the cruise state, the second preset range is in the range of 0.75 - 1.25 times the nth-order natural frequency of the tail boom; when the helicopter is in the normal yaw state, the second preset range is in the range of 0.8 - 1.2 times the nth-order natural frequency of the tail boom; when the helicopter is in the extreme yaw state, the second preset range is in the range of 0.9 - 1.1 times the nth-order natural frequency of the tail boom.

[0020] Thus, by adjusting the rotational speed of the helicopter tail rotor to avoid a specific range of the nth natural frequency of the tail boom, the problem of high-order resonance of the tail boom can be effectively avoided, thereby reducing the vibration level of the tail boom, improving the structural stability of the helicopter, especially the unmanned helicopter, and ensuring good flight attitude and flight state.

[0021] According to an embodiment of the present invention, when the operation stage is the ground start-up stage, the rotational speed of the tail rotor is closed-loop controlled to make the rotational speed of the tail rotor when the helicopter is stable avoid the first preset range; when the operation stage is the in-air flight stage, in the step of making the rotational speed of the tail rotor avoid the second preset range, it includes: Determine the interval width of the first preset range and the second preset range, as well as the nth natural frequency of the tail boom and the rated rotational speed of the tail rotor; According to the rated rotational speed of the tail rotor, the nth natural frequency of the tail boom, and the interval width of the first preset range, determine the time threshold for the rotational speed of the tail rotor to avoid the first preset range; According to the rated rotational speed of the tail rotor, the nth natural frequency of the tail boom, and the interval width of the second preset range, determine the time threshold for the rotational speed of the tail rotor to avoid the second preset range.

[0022] Thus, according to the time threshold, the time for the tail rotor rotation to fall into the first preset range or the second preset range during the helicopter navigation process can be minimized, that is, the specific range of the nth natural frequency of the tail rotor can be crossed as soon as possible, thereby reducing the vibration amplitude of the tail boom as much as possible and improving the smoothness of the navigation.

[0023] According to an embodiment of the present invention, the calculation methods of the time thresholds for the rotational speed of the tail rotor to avoid the first preset range and the second preset range are the same, and are calculated according to the following formula: ; In the formula, t is the time threshold, ΔΩ is the interval width of the first preset range or the second preset range; Ω’ is the rated rotational speed of the tail rotor; J is the moment of inertia of the tail rotor motor; T is the rated torque of the tail rotor motor; ω n is the nth natural frequency of the tail boom; k 2 is an empirical coefficient.

[0024] Empirical coefficient k 2 is calculated according to the following formula: ; In the formula, C is a dimensionless proportionality constant, and the initial value is generally set to 0.2 - 0.3; A max is the allowable vibration acceleration amplitude of the tail boom; ζis the damping ratio of the tail beam structure; Ω is the tail rotor speed; J is the moment of inertia of the tail rotor motor; T is the rated torque of the tail rotor motor.

[0025] According to one aspect of the present invention, there is provided a helicopter tail rotor speed control device, including: a data acquisition module for acquiring the position information of the helicopter; an analysis module for determining the operation stage of the helicopter according to the position information, and the operation stage includes a ground start stage and an in-air flight stage; a speed regulation module for regulating the speed of the tail rotor according to the operation stage; wherein, when the operation stage is the ground start stage, a closed-loop control is performed on the tail rotor speed to avoid the first preset range when the helicopter is stable; when the operation stage is the in-air flight stage, the tail rotor speed is avoided from the second preset range; the first preset range is the preset range of resonance between the tail rotor and the tail beam during the ground start stage, and the second preset range is the preset range of resonance between the tail rotor and the tail beam during the in-air flight stage.

[0026] According to one aspect of the present invention, there is provided a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the helicopter tail rotor speed control method of any of the above embodiments is implemented.

[0027] According to one aspect of the present invention, there is provided a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the helicopter tail rotor speed control method of any of the above embodiments is implemented.

[0028] Compared with the prior art, the present invention at least includes the following beneficial effects: 1. In the ground start stage of the present invention, the tail rotor speed is controlled and adjusted based on the linear relationship between the tail rotor speed and the main rotor speed, effectively solving the problem of the helicopter spinning in place during the ground start stage due to insufficient ground static friction of the landing gear and mismatching of the rotational torques of the main rotor and the tail rotor.

[0029] 2. In the ground start stage of the present invention, a closed-loop control is performed on the tail rotor speed and the main rotor speed, effectively solving the attitude control problem caused by the independent electric drive control of the main rotor and the tail rotor, and making the helicopter attitude control smoother.

[0030] 3. By regulating the helicopter tail rotor speed to avoid a specific range of the nth natural frequency of the tail beam, the present invention can effectively avoid the problem of high-order resonance of the tail beam, thereby reducing the vibration level of the tail beam, reducing the displacement at the end of the tail beam, improving the structural stability of the helicopter, especially the unmanned helicopter, and ensuring good flight attitude and flight state. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments and descriptions thereof of the invention are used to explain the invention and shall not unduly limit the invention. In the drawings: Figure 1 It is a structural block diagram for implementing closed-loop control of the tail rotor speed and the main rotor speed by using PID control in the helicopter tail rotor speed control method according to Embodiment 1 of the present invention; Figure 2 It is a structural block diagram for implementing closed-loop control of the tail rotor speed and the main rotor speed by using other control in the helicopter tail rotor speed control method according to Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be described in detail below with reference to the drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0033] The following detailed descriptions are all exemplary descriptions, aiming to provide a further detailed description of the present invention. Unless otherwise specified, all technical terms adopted by the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0034] Embodiment 1 A helicopter tail rotor speed control method, which is applied to a helicopter, especially for the speed regulation of the tail rotor of an unmanned helicopter, includes the following steps: Obtain the position information of the helicopter; Determine the operation stage of the helicopter according to the position information, and the operation stage includes a ground start-up stage and an in-air flight stage; Regulate the speed of the tail rotor according to the operation stage; wherein, when the operation stage is the ground start-up stage, perform closed-loop control on the tail rotor speed so that the tail rotor speed when the helicopter is stable avoids the first preset range; when the operation stage is the in-air flight stage, make the tail rotor speed avoid the second preset range.

[0035] The first preset range is the preset range in which resonance occurs between the tail rotor and the tail boom during the ground start-up stage; the second preset range is the preset range in which resonance occurs between the tail rotor and the tail boom during the in-air flight stage.

[0036] It should be noted that "when the helicopter is stable" means that the main rotor speed and the tail rotor speed reach the preset idle speed or ground operation value, and the fluctuation range is within the allowable threshold. Generally, the allowable threshold of the fluctuation range is ±(3 - 5)%. At this time, the engine torque or power output is stable without abnormal fluctuations.

[0037] With the above technical solution, for a helicopter with independent control of the main rotor and the tail rotor, it can avoid spinning in place due to the torque mismatch formed by the rotation of the main rotor and the tail rotor during the ground startup phase, effectively reduce the vibration level of the helicopter's tail boom during the air flight phase, reduce the displacement of the end of the tail boom, and improve the structural stability.

[0038] Specifically, the method for controlling the rotational speed of the tail rotor of the helicopter in this embodiment includes the following steps: S1. Obtain the position information of the helicopter.

[0039] Use a sensor to obtain the coordinates (x, y, z) of the helicopter in the ground coordinate system; and obtain the attitude angle information of the helicopter, including the pitch angle θ , yaw angle ψ and roll angle Φ .

[0040] S2. Determine the operating phase of the helicopter according to the position information, and the operating phase includes the ground startup phase and the air flight phase.

[0041] Determine the operating phase of the helicopter according to the z-axis coordinate of the helicopter in the ground coordinate system. The operating phase includes the ground startup phase and the air flight phase.

[0042] When the z-axis coordinate of the helicopter in the ground coordinate system is 0 or close to 0, it is determined that the helicopter is in the ground startup phase. When the z-axis coordinate of the helicopter in the ground coordinate system is much greater than 0, it is determined that the helicopter is in the air flight phase. Generally, if the barometric altitude of the helicopter ≤ (landing gear height + 0.5 m), it is considered that the helicopter is in the ground startup phase. If the barometric altitude > (landing gear height + 3 m), it is considered that the helicopter is in the air flight phase.

[0043] To improve the accuracy of judging the operating phase, it can also be determined by combining other parameter indicators. For example, obtain the engine torque value, and combine it with the position information of the helicopter. If the engine torque < 20% and the change rate ≤ 5% / s, it is determined that it is in the ground startup phase. If the engine torque > 25% or the change rate ≥ 10% / s, it is determined that it is in the air flight phase; in addition, it can also be determined by combining indicators such as the main rotor speed and the vertical speed.

[0044] S3. Regulate the rotational speed of the tail rotor according to the operating phase; among them, when the operating phase is the ground startup phase, perform closed-loop control on the rotational speed of the tail rotor to avoid the first preset range when the helicopter is stable; when the operating phase is the air flight phase, avoid the second preset range.

[0045] S3-1. When the operation phase is the ground start-up phase, perform closed-loop control on the tail rotor speed so that the tail rotor speed when the helicopter is stable avoids the first preset range, including: When the main rotor starts to rotate, the controlled speed of the tail rotor should be linearly related to the speed of the main rotor. The linear relationship between the tail rotor speed and the main rotor speed is as follows: ; In the formula, k 1 is the correlation coefficient, Ω t is the tail rotor speed; Ω m is the main rotor speed.

[0046] Among them, the initial value of the correlation coefficient k 1 can be calculated according to the following formula: ; In the formula, C P is the main rotor power coefficient; R m is the main rotor radius; C t is the tail rotor thrust coefficient; R t is the tail rotor radius; L is the distance between the thrust axis or pull axis of the helicopter tail rotor and the main rotor shaft.

[0047] After the helicopter starts, the speeds of the main rotor and the tail rotor gradually increase. The value of the correlation coefficient k 1 can be corrected based on the initial value according to the speed changes of the main rotor and the tail rotor.

[0048] The correlation coefficient k 1 is corrected according to the following formula: ; In the formula, is the corrected correlation coefficient, is the initial value of the correlation coefficient; F ρ is the air density correction factor, ω ρ is F ρ the weight of; F Ω is the main rotor speed correction factor, ω Ω is F Ω the weight of; Among them, , the weight distribution can be based on experience or actual influence.

[0049] ; In the formula, ρ is the actual air density, with the unit of kg / m 3 ; ρ 0 is the standard air density, with the unit of kg / m 3 .

[0050] ; In the formula, Ω m is the real-time rotational speed of the main rotor, with the unit of RPM; Ω m,ref is the rated rotational speed of the main rotor in the hover state, with the unit of RPM; is the rotational speed coupling coefficient, which is an empirical coefficient, generally taking a value of 0.15, reflecting the sensitivity of the change in the rotational speed of the main rotor; is the non-linear correction exponent, which is an empirical exponent, generally taking a value of 1.2, characterizing the non-linear response of the aerodynamic load.

[0051] Since the main rotor and the tail rotor of the helicopter are independently controlled, there may be problems of timing or rotational speed mismatch between the two electric drive systems corresponding to the main rotor and the tail rotor during operation. Therefore, for the control method of the tail rotor rotational speed, closed-loop control is performed based on the above linear relationship between the tail rotor rotational speed and the main rotor rotational speed. See Figure 1 , Figure 1 , where r(t) represents the input of the PID closed-loop control, which is the expected value of the tail rotor rotational speed calculated based on the main rotor rotational speed in this scheme; y(t) represents the feedback of the PID closed-loop control, which is the actual value of the tail rotor rotational speed in this scheme; e(t) represents the error in the PID closed-loop control, which is the error between the expected value of the tail rotor rotational speed and the actual value of the tail rotor rotational speed in this scheme; u(t) represents the output of the PID closed-loop control, which is the tail rotor rotational speed command in this scheme.

[0052] The specific control process includes: (1) Use sensors to obtain the current rotational speeds of the main rotor and the tail rotor.

[0053] (2) According to the linear relationship between the tail rotor rotational speed and the main rotor rotational speed, calculate the expected value of the tail rotor rotational speed using the collected rotational speed of the main rotor; calculate the error e(t) based on the expected value of the tail rotor rotational speed and the currently collected rotational speed of the tail rotor; Input the error e(t) into the proportional, integral, and derivative links of the PID controller respectively, superimpose the outputs of the proportional, integral, and derivative links to obtain the adjustment amount of the tail rotor rotational speed and thus obtain the tail rotor rotational speed command u(t), and send the tail rotor rotational speed command u(t) to the controlled object, that is, the tail rotor drive motor.

[0054] (3) The tail rotor drive motor controls the rotational speed of the tail rotor according to the received tail rotor speed command u(t).

[0055] In addition, the PID control in this embodiment can also be replaced by algorithms such as PI control and adaptive control to achieve closed-loop control of the tail rotor speed. For the control structure block diagram, see Figure 2 .

[0056] When the helicopter is stable, that is, when the main rotor speed and the tail rotor speed reach the preset idle speed or ground operation value and the fluctuation range is within the allowable threshold, adjust the tail rotor speed to avoid the first preset range. The first preset range is 0.7 - 1.3 times the range of the nth natural frequency ω n of the tail boom.

[0057] S3-2. When the operation stage is the in-air flight stage, make the tail rotor speed avoid the second preset range, including: Determine the flight state according to the position information and attitude angle information of the helicopter; adjust the interval width of the second preset range according to the flight state.

[0058] When the helicopter is in the in-air flight stage, determine the flight state according to the coordinates (x, y, z) of the helicopter in the ground coordinate system obtained by the sensor and the attitude angle information in the body coordinate system; the flight states include hover state, cruise state, normal yaw state, and extreme yaw state.

[0059] The attitude angle information includes: pitch angle θ , yaw angle ψ and roll angle Φ , the three angular velocity components p , q , r of the body coordinate system, and the three velocity components u , v , w of the body coordinate system.

[0060] The three angular velocity components p , q , r of the body coordinate system are the components of the rotational angular velocity of the body coordinate system of the helicopter relative to the ground coordinate system on each axis of the body coordinate system; among them, the angular velocity p coincides with the body axis ox b , the angular velocity q coincides with the body axis oy b , and the angular velocity r coincides with the body axis oz b . The three velocity components u ,v , w are the components of the helicopter's flight speed v on each axis of the body coordinate system; among them, u coincides with the body axis ox b exactly, v coincides with the body axis oy b exactly, w coincides with the body axis oz b exactly.

[0061] Furthermore, the attitude angle information also includes the yaw angular velocity ; as needed, it can also include the pitch angular velocity and the roll angular velocity .

[0062] Among them, in the hover state: the x, y, and z coordinates of the helicopter remain unchanged, and the pitch angle θ , yaw angle ψ and roll angle Φ remain unchanged, and the angular velocity components p , q , r are all 0, and the speed components u , v , w are all 0.

[0063] In the cruise state: the y and z coordinates of the helicopter remain unchanged, and the pitch angle θ , yaw angle ψ and roll angle Φ remain unchanged, and the angular velocity components p , q , r are all 0, the speed component u is a constant value, and v and w are both 0.

[0064] The initial conditions for the normal yaw state and the extreme yaw state are the same. The initial conditions are: the z-axis coordinate of the helicopter remains unchanged, and the pitch angle θ and roll angle Φ remain unchanged, the yaw angle ψ varies linearly, the angular velocity components p , q are both 0, r is a constant value, and the speed component w is 0. After a certain period of time, the normal yaw state and the extreme yaw state can be distinguished according to the yaw angular velocity . If 30° / s ≤ < 60° / s, then the helicopter is in the normal yaw state; if 60° / s ≤ ≤ 120° / s, then the helicopter is in the extreme yaw state.

[0065] When the helicopter is in a hover state, to counteract certain external disturbances and maintain the hover state through fine-tuning of the tail rotor, the yaw angular velocity range is usually small, assumed to be set within the range of 5 - 15° / s. The rotational speed adjustment control scheme of the helicopter tail rotor is set to avoid a specific range of the nth natural frequency ω of the tail boom. n Specifically, the second preset range is adjusted to a range of 0.7 - 1.3 times the nth natural frequency ω of the tail boom. n When the helicopter is in a cruise state, to maintain a certain heading state during flight and maintain the heading state through tail rotor adjustment, the yaw angular velocity is usually set within the range of 10 - 30° / s. The rotational speed adjustment control scheme of the helicopter tail rotor is set to avoid a specific range of the nth natural frequency ω of the tail boom. n Specifically, the second preset range is adjusted to a range of 0.75 - 1.25 times the nth natural frequency ω of the tail boom. n When the helicopter is yawing normally, to achieve a certain heading state during flight and perform yaw movement through tail rotor adjustment, the yaw angular velocity is usually set within the range of 30 - 60° / s. The rotational speed adjustment control scheme of the helicopter tail rotor is set to avoid a specific range of the nth natural frequency ω of the tail boom. n Specifically, the second preset range is adjusted to a range of 0.8 - 1.2 times the nth natural frequency ω of the tail boom. n When the helicopter is in extreme yaw, to achieve a certain heading state during flight and perform yaw movement through tail rotor adjustment, the yaw angular velocity is usually set within the range of 60 - 120° / s. The rotational speed adjustment control scheme of the helicopter tail rotor is set to avoid a specific range of the nth natural frequency ω of the tail boom. n Specifically, the second preset range is adjusted to a range of 0.9 - 1.1 times the nth natural frequency ω of the tail boom. n

[0066] Regulating the specific range of the rotational speed of the helicopter tail rotor to avoid the nth natural frequency of the tail boom can effectively avoid the problem of high-order resonance of the tail boom, thereby reducing the vibration level of the tail boom, improving the structural stability of the helicopter, especially the unmanned helicopter, and ensuring good flight attitude and flight state.

[0067] Furthermore, during the process of regulating the rotational speed of the tail rotor, try to shorten the time when the rotation of the tail rotor during the helicopter's navigation falls into the first preset range or the second preset range, that is, quickly cross the specific range of the nth natural frequency of the tail rotor, so as to reduce the vibration amplitude of the tail boom as much as possible and improve the smoothness of the navigation.

[0068] Therefore, when the operation stage is the ground start-up stage, the closed-loop control is performed on the tail rotor speed so that the tail rotor speed when the helicopter is stable avoids the first preset range; when the operation stage is the in-air flight stage, in the step of making the tail rotor speed avoid the second preset range, the following steps are included: Determine the interval widths of the first preset range and the second preset range, as well as the nth-order natural frequency of the tail boom and the rated speed of the tail rotor; According to the rated speed of the tail rotor, the nth-order natural frequency of the tail boom, and the interval width of the first preset range, determine the time threshold for the tail rotor speed to avoid the first preset range; According to the rated speed of the tail rotor, the nth-order natural frequency of the tail boom, and the interval width of the second preset range, determine the time threshold for the tail rotor speed to avoid the second preset range.

[0069] The calculation methods of the time thresholds for the tail rotor speed to avoid the first preset range and the second preset range are the same, and are calculated according to the following formula: ; In the formula, t is the time threshold, ΔΩ is the interval width of the first preset range or the second preset range; Ω’ is the rated speed of the tail rotor; J is the moment of inertia of the tail rotor motor; T is the rated torque of the tail rotor motor; ω n is the nth-order natural frequency of the tail boom; k 2 is an empirical coefficient.

[0070] Empirical coefficient k 2 is calculated according to the following formula: ; In the formula, C is a dimensionless proportional constant, and the initial value is generally set to 0.2 - 0.3; A max is the allowable amplitude of the vibration acceleration of the tail boom; ζ is the damping ratio of the tail boom structure; Ω is the tail rotor speed; J is the moment of inertia of the tail rotor motor; T is the rated torque of the tail rotor motor.

[0071] Thus, by adopting the helicopter tail rotor speed control method of this embodiment, regulating the helicopter tail rotor speed to avoid a specific range of the nth-order natural frequency of the tail boom can avoid the problem of the helicopter spinning on the ground, and can also effectively avoid the problem of high-order resonance of the tail boom, thereby reducing the vibration level of the tail boom, reducing the displacement at the end of the tail boom, improving the structural stability of the helicopter, especially the unmanned helicopter, and ensuring good flight attitude and flight state.

[0072] Embodiment 2 This embodiment provides a method for controlling the rotational speed of a helicopter tail rotor, which is different from Embodiment 1 in that: During the ground start-up phase, the first preset range is 0.7 - 1.3 times the nth natural frequency of the tail boom; During the in-air flight phase, when the helicopter is in a hover state, the second preset range is 0.5 - 1.5 times the nth natural frequency of the tail boom; When the helicopter is in a cruise state, the second preset range is 0.7 - 1.3 times the nth natural frequency of the tail boom; When the helicopter is in a normal yaw state, the second preset range is 0.7 - 1.3 times the nth natural frequency of the tail boom; When the helicopter is in an extreme yaw state, the second preset range is 0.8 - 1.2 times the nth natural frequency of the tail boom.

[0073] Embodiment 3 A device for controlling the rotational speed of a helicopter tail rotor includes: A data acquisition module for obtaining the position information of the helicopter; An analysis module for determining the operation phase of the helicopter according to the position information, and the operation phase includes a ground start-up phase and an in-air flight phase; A rotational speed regulation module for regulating the rotational speed of the tail rotor according to the operation phase; wherein, when the operation phase is the ground start-up phase, a closed-loop control is performed on the rotational speed of the tail rotor to make the rotational speed of the tail rotor when the helicopter is stable avoid the first preset range; when the operation phase is the in-air flight phase, the rotational speed of the tail rotor is made to avoid the second preset range; the first preset range is the preset range in which resonance occurs between the tail rotor and the tail boom during the ground start-up phase, and the second preset range is the preset range in which resonance occurs between the tail rotor and the tail boom during the in-air flight phase.

[0074] Embodiment 4 A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for controlling the rotational speed of the helicopter tail rotor in Embodiment 1 or Embodiment 2 is implemented.

[0075] Embodiment 5 A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the method for controlling the rotational speed of the helicopter tail rotor in Embodiment 1 or Embodiment 2 is implemented.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for controlling the rotational speed of a helicopter tail rotor, characterized in that, It includes the following steps: Obtain the position information of the helicopter; Determine the operation stage of the helicopter according to the position information, where the operation stage includes a ground start stage and an air flight stage; Regulate the rotational speed of the tail rotor according to the operation stage; among them, when the operation stage is the ground start stage, perform closed-loop control on the rotational speed of the tail rotor to avoid the first preset range for the rotational speed of the tail rotor when the helicopter is stable; when the operation stage is the air flight stage, avoid the second preset range for the rotational speed of the tail rotor; the first preset range is the preset range where resonance occurs between the tail rotor and the tail boom during the ground start stage, and the second preset range is the preset range where resonance occurs between the tail rotor and the tail boom during the air flight stage.

2. The method for controlling the rotational speed of the tail rotor of a helicopter according to claim 1, wherein When the operation stage is the ground start stage, the step of performing closed-loop control on the rotational speed of the tail rotor to avoid the first preset range for the rotational speed of the tail rotor when the helicopter is stable includes: Obtain the current main rotor rotational speed and tail rotor rotational speed; Based on the current main rotor rotational speed and tail rotor rotational speed, obtain the adjustment amount of the tail rotor rotational speed based on the linear relationship between the tail rotor rotational speed and the main rotor rotational speed; Adjust the rotational speed of the tail rotor according to the adjustment amount of the tail rotor rotational speed to avoid the first preset range for the rotational speed of the tail rotor when the helicopter is stable.

3. The method for controlling the rotational speed of the tail rotor of a helicopter according to claim 1, wherein The first preset range is in the range of 0.5 - 1.5 times the nth natural frequency of the tail boom.

4. The method for controlling the rotational speed of the tail rotor of a helicopter according to claim 1, wherein When the helicopter is in the air flight stage, determine the flight state according to the position information and attitude angle information of the helicopter; adjust the interval width of the second preset range according to the flight state; The flight states include a hover state, a cruise state, a normal yaw state, and an extreme yaw state.

5. The method for controlling the rotational speed of the tail rotor of a helicopter according to claim 4, wherein When the helicopter is in the hover state, the second preset range is in the range of 0.5 - 1.5 times the nth natural frequency of the tail boom; When the helicopter is in the cruise state, the second preset range is in the range of 0.7 - 1.3 times the nth natural frequency of the tail boom; When the helicopter is in the normal yaw state, the second preset range is in the range of 0.7 - 1.3 times the nth natural frequency of the tail boom; When the helicopter is in the extreme yaw state, the second preset range is in the range of 0.8 - 1.2 times the nth natural frequency of the tail boom.

6. The method for controlling the rotational speed of the tail rotor of a helicopter according to claim 1, wherein When the operation stage is the ground start stage, perform closed-loop control on the rotational speed of the tail rotor to avoid the first preset range for the rotational speed of the tail rotor when the helicopter is stable; In the step of avoiding the second preset range for the rotational speed of the tail rotor when the operation stage is the air flight stage, it includes: Determine the interval widths of the first preset range and the second preset range, as well as the nth natural frequency of the tail boom and the rated rotational speed of the tail rotor; According to the rated rotational speed of the tail rotor, the nth natural frequency of the tail boom, and the interval width of the first preset range, determine the time threshold for the rotational speed of the tail rotor to avoid the first preset range; Determine the time threshold for the tail rotor speed to avoid the second preset range according to the rated speed of the tail rotor, the nth natural frequency of the tail boom, and the interval width of the second preset range.

7. The helicopter tail rotor speed control method according to claim 6, wherein: The calculation methods of the time thresholds for the tail rotor speed to avoid the first preset range and the second preset range are the same, and are calculated according to the following formula: ； In the formula, t is the time threshold, ΔΩ is the interval width of the first preset range or the second preset range; Ω’ is the rated speed of the tail rotor; J is the rated torque of the tail rotor motor; T is the moment of inertia of the tail rotor motor; ω is the natural frequency of the tail boom; k 2 is the empirical coefficient.

8. Helicopter tail rotor speed control device, characterized in that, including: A data acquisition module for acquiring the position information of the helicopter; An analysis module for determining the operating stage of the helicopter according to the position information, where the operating stage includes a ground start stage and an in-air flight stage; A speed regulation module for regulating the speed of the tail rotor according to the operating stage; wherein, when the operating stage is the ground start stage, a closed-loop control is performed on the tail rotor speed to make the tail rotor speed when the helicopter is stable avoid the first preset range; when the operating stage is the in-air flight stage, the tail rotor speed is made to avoid the second preset range; the first preset range is the preset range in which the tail rotor and the tail boom resonate during the ground start stage, and the second preset range is the preset range in which the tail rotor and the tail boom resonate during the in-air flight stage.

9. An electronic device, characterized in that, including a processor and a memory, the processor is configured to execute a computer program stored in the memory to implement the helicopter tail rotor speed control method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by the processor, the helicopter tail rotor speed control method according to any one of claims 1 to 7 is implemented.

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