Helicopter resonance early warning method and device

Abstract

The invention discloses a helicopter resonance early warning method and device, and the device comprises a rotary encoder which is disposed in a shimmy hinge rotating shaft of a propeller hub, the bottom of the rotary encoder is fixed to the rotating shaft, and a knob at the top of the rotary encoder is connected with a helicopter blade through a connecting piece. Angular displacement mechanical signals of the blades are converted into electric signals through the rotary encoder; the linear encoder is arranged in the hydraulic shimmy damper and comprises a ruler body and a pull rod, the hydraulic shimmy damper comprises a shell and a piston rod, the tail end of the ruler body is fixedly installed on the inner wall of the shell through a support, and the front end of the pull rod is hinged to the piston rod; and the controller reads and processes the digital signals transmitted by the rotary encoder and the linear encoder in real time, compares the real-time signals with a preset threshold value, and gives an alarm. And meanwhile, the blade shimmy motion and the shimmy damper working state are monitored to predict resonance, and the two are mutually verified, so that the prediction accuracy and reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of resonance warning, in particular to a helicopter resonance warning method and device. BACKGROUND

[0002] Currently, in the field of helicopter engineering, the following three types of traditional technical means are mainly used to avoid and control the risk of ground resonance / air resonance (hereinafter referred to as "resonance"): 1. Design avoidance: In the design stage of the helicopter, by adjusting the landing gear stiffness, rotor system parameters and other methods, the rotor aft type of oscillation frequency is staggered with the inherent frequency of the fuselage on the landing gear, so as to avoid the occurrence of frequency matching from the source; 2. Add damping mechanism: Install hydraulic or elastomer anti-swing device in the rotor system, which aims to absorb the energy generated by the blade oscillation, increase the system damping, and thus inhibit the expansion of vibration amplitude; 3. Standard operation and maintenance: Develop strict operating procedures (such as requiring pilots to operate smoothly, avoid specific weather conditions) and maintenance manuals (such as keeping the landing gear cushion pressure balanced, regularly checking the anti-swing device status).

[0003] However, the above existing technologies have obvious deficiencies and limitations: Lack of active warning capability (fundamental defect): The existing means all belong to the category of "passive prevention". They cannot monitor the budding state of resonance in real time during the operation of the helicopter, and cannot provide any form of warning signal before the accident occurs. Pilots and maintenance personnel cannot know whether the system is currently heading towards a loss of control, and can only rely on the safety margin of the design and daily maintenance to "hope" that the accident does not occur.

[0004] Cannot respond to sudden conditions: The safety margin of the design may be broken by sudden factors, for example, sudden unevenness of the runway, severe crosswind disturbance or instantaneous attenuation of the anti-swing device performance, which may become the cause of resonance. The existing technology lacks effective measures to respond to such dynamic and sudden risks.

[0005] Dependence on manual judgment, poor reliability: The current judgment of whether the helicopter state is normal relies heavily on the pilot's senses (such as feeling abnormal vibration) and the regular inspection of ground personnel. This method is highly subjective and has a serious lag. Often when the pilot feels severe vibration, resonance may have occurred or is about to enter an irreversible stage, leaving a very short time window for disposal, and it is easy to miss the best opportunity for disposal.

[0006] Single monitoring means, inaccurate prediction: It is impossible to obtain the most critical and interrelated multi-dimensional data for predicting resonance, so it is impossible to make accurate risk assessment and prediction.

[0007] In summary, the biggest blank of the prior art is that there is no active early warning system capable of monitoring resonance risks in real time and accurately and issuing early warnings, so that the helicopter is always in a passive situation when facing resonance threats. SUMMARY

[0008] The application provides a helicopter resonance early warning method and device, which can monitor resonance risks in real time and accurately and issue early warnings, so as to solve the problems of poor resonance early warning reliability, inaccurate prediction and single monitoring means in the prior art.

[0009] To achieve the above object, the application provides the following technical scheme: a helicopter resonance early warning device, comprising: A rotary encoder is arranged in a pendulum hinge shaft of a hub, the bottom of the rotary encoder is fixed to the shaft, and the knob at the top of the rotary encoder is connected with the helicopter blade through a connecting piece, so that when the blade swings, the knob rotates, and the rotary encoder converts the angular displacement mechanical signal of the blade into an electrical signal; A linear encoder is arranged in a hydraulic pendulum damper, comprising a ruler body and a pull rod, the hydraulic pendulum damper comprises a shell and a piston rod, the tail end of the ruler body is fixedly installed on the inner wall of the shell through a support, and the front end of the pull rod is hinged with the piston rod. A controller reads and processes digital signals transmitted by the rotary encoder and the linear encoder in real time, compares the real-time signals with preset threshold values, and issues warnings.

[0010] As a further improvement of the above technical scheme: The connecting piece is a connecting rod or a shaft coupling and is made of high-strength aluminum alloy material, one end of the connecting piece is connected with the knob, and the other end of the connecting piece is connected with the root of the helicopter blade.

[0011] The rotary encoder is a hollow shaft absolute rotary encoder, and the inner diameter of the rotary encoder matches the size of the pendulum hinge shaft.

[0012] The linear encoder is a magnetic grating linear encoder, and the range of the linear encoder is greater than the maximum stroke of the piston rod.

[0013] The main control chip of the controller is an industrial-grade ARM Cortex-M series MCU, the controller has a multi-channel encoder interface and a CAN bus interface, and is used for cross-linking with an airborne avionics system of the helicopter.

[0014] The application further discloses a helicopter resonance early warning method, comprising: S1: The rotary encoder detects the pendulum angular displacement change of the helicopter blade in real time, generates and outputs a digital signal n1 to the controller; S2: The linear encoder detects the linear displacement change of the pendulum rod in real time, generates and outputs a digital signal n2 to the controller; S3: The controller receives the digital signals n1 and n2, and performs preprocessing such as filtering and denoising on the signals; The processed real-time data are compared with a preset threshold value in the storage unit; the threshold value corresponds to the abnormal state critical value of the dramatic increase of the blade oscillation movement and the high-speed operation of the pendulum before the helicopter resonates for 2±0.5s.

[0015] S4: When any of n1 or n2 exceeds the preset threshold value, the controller immediately triggers the alarm device to issue a warning signal.

[0016] Compared with the prior art, the present application has the following advantages: Active early warning is achieved: the traditional "passive prevention" is changed to "active early warning", which can issue an alarm at the budding stage of resonance (such as 2 seconds in advance), completely changing the passive situation of only post-repair, and greatly improving the safety.

[0017] High prediction accuracy and strong reliability: through double-sensor information fusion (blade angle + pendulum displacement), the resonance risk is judged together in two dimensions, compared with single signal monitoring, effectively avoiding false positives and false negatives, and the judgment result is more scientific and accurate.

[0018] Provides key decision-making time for disposal: although the 2-second warning window is short, it is enough for the pilot to identify the alarm and take key operations such as reducing power and terminating take-off and landing, thereby cutting off the energy cycle of resonance and fundamentally avoiding accidents.

[0019] Simple structure, easy to implement and promote: the device core uses mature industrial encoders, which are low in cost and small in modification difficulty. Without large-scale modification of the main structure of the helicopter, it is mainly realized by adding and integrating, which is convenient for adding and modifying in the existing fleet, has strong universality, and has significant economic benefits.

[0020] Convenient maintenance: compared with pure mechanical systems, electronic monitoring devices are more convenient for data recording and fault diagnosis, providing data support for subsequent maintenance and system optimization. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is one of the overall structure schematic diagram of the present application; Figure 2 is the second overall structure schematic diagram of the present application; Figure 3 is a schematic diagram of the installation structure of the rotary encoder of the present application; Figure 4 is a schematic diagram of the installation structure of the linear encoder of the present application; Figure 5 The flow chart of the early warning method of the application is shown in the figure.

[0022] Reference numerals: 1, connecting piece; 10, knob; 2, rotary encoder; 3, paddle; 4, hydraulic pendulum damper; 5, linear encoder; 6, shell; 7, ruler body; 8, pull rod; 9, piston rod. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme of the application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application.

[0024] As shown in the figure, the embodiment takes a certain type of medium-sized general helicopter with a full-hinged rotor system and a hydraulic pendulum damper as an implementation platform. The early warning device of the helicopter resonance of the embodiment comprises: Figures 1 to 4 The rotary encoder 2 is arranged in the pendulum hinge shaft of the hub, the bottom of which is fixed to the shaft, and the knob 10 at the top thereof is connected with the helicopter paddle 3 through the connecting piece 1. When the paddle 3 swings, it will drive the knob 10 to rotate, and the angular displacement mechanical signal of the paddle will be converted into an electrical signal through the rotary encoder. The rotary encoder 2 selects a high-precision, impact-resistant hollow shaft absolute rotary encoder, the inner diameter of which matches the size of the pendulum hinge shaft, and the rated speed meets the maximum speed requirement of the rotor. When the rotary encoder 2 is installed: open the pendulum hinge cover plate on the helicopter hub. Fix the base of the rotary encoder 2 to the end face of the hinge shaft. Then, one end of the connecting piece 1 is keyed connected with the encoder knob 10, and the other end is hinged with the appropriate position of the root of the paddle 3. Ensure that the paddle can smoothly drive the encoder to rotate without jamming when it swings.

[0025] The linear encoder 5 is arranged inside the hydraulic pendulum damper 4, which comprises a ruler body 7 and a pull rod 8. The hydraulic pendulum damper 4 comprises a shell 6 and a piston rod 9. The tail end of the ruler body 7 is fixedly installed on the inner wall of the shell 6 through a bracket, and the front end of the pull rod 8 is hinged with the piston rod 9. The linear encoder 5 selects a small, oil-proof, magnetic grid linear encoder, the range of which is slightly larger than the maximum stroke of the pendulum damper piston, and the resolution is sufficient to capture the high-speed and small displacement changes.

[0026]

[0027] ​Linear encoder installation: open the end cover of the hydraulic pendulum damper 4. The tail of the linear encoder ruler 7 is fixed on the inner wall of the pendulum damper shell 6 through the support. The front end of the linear encoder pull rod 8 is connected with the end of the pendulum damper piston rod 9 through a universal ball head. This can compensate for the possible coaxiality error and prevent the force from being blocked.

[0028] Wiring: the cables of the two encoders are reliably fixed along the original wire harness path and finally introduced into the cockpit and connected with the controller.

[0029] The controller reads and processes the digital signals from the rotary encoder 2 and the linear encoder 5 in real time, compares the real-time signals with the preset threshold, and issues a warning. The main control chip of the controller is an industrial-grade ARM Cortex-M series MCU. The controller has a multi-channel encoder interface and a CAN bus interface for cross-linking with the helicopter airborne avionics system.

[0030] The connecting piece 1 is a connecting rod or a coupling, made of high-strength aluminum alloy material, one end of the connecting piece 1 is connected with the knob 10, and the other end is connected with the root of the helicopter blade 3. Ensure the rigidity and precision of the connection with the blade and the encoder knob.

[0031] The linear encoder 5 is a magnetic grating linear encoder, and its range is greater than the maximum stroke of the piston rod 9.

[0032] The helicopter resonance warning method of the embodiment is based on the helicopter resonance warning device of any one of claims 1 to 5, comprising: S1: The rotary encoder 2 detects the change of the swing angle displacement of the helicopter blade 3 in real time, generates and outputs a digital signal n1 to the controller; S2: The linear encoder 5 detects the change of the linear displacement of the pendulum damper piston rod 9 in real time, generates and outputs a digital signal n2 to the controller; S3: The controller receives the digital signals n1 and n2, and performs preprocessing such as filtering and denoising on the signals; Compare the processed real-time data with the preset threshold value in the storage unit; S4: When either n1 or n2 exceeds its preset threshold value, the controller immediately triggers the alarm device and issues a warning signal.

[0033] The threshold corresponds to the abnormal state critical value of the dramatic increase in blade swing motion and high-speed operation of the pendulum damper 2±0.5 seconds before the helicopter resonance occurs. Through ground tests and analysis of a large amount of historical data (including resonance test data), the change rate threshold (dn1 / dt) of the rotary encoder reading and the change rate threshold (dn2 / dt) of the linear encoder reading are determined 2±0.5 seconds before the resonance occurs. The above threshold is solidified and stored in the storage unit (such as FLASH) of the controller.

[0034] The controller software performs the following flow in real time: read the encoder signal -> first-order filtering -> calculate the instantaneous rate of change -> compare with threshold -> over-limit drive alarm (such as display screen warning information, buzzer ringing).

[0035] Working process: When the helicopter is in the take-off / landing stage, if the initial vibration is induced by runway bumps or operation, and if the vibration has the tendency to cause resonance, then: The amplitude and frequency of the blade oscillation will abnormally increase, causing the change rate of the rotary encoder 2 signal n1 to exceed the threshold.

[0036] At the same time, the anti-swing device will move at high speed and frequently to consume energy, causing the change rate of the linear encoder 5 signal n2 to exceed the threshold.

[0037] The controller detects any over-limit event within milliseconds and immediately triggers an audible and visual alarm in the cockpit: "resonance warning! Please handle immediately!"

[0038] The pilot quickly raises the collective lever to reduce the load or performs other correction procedures according to the training program, successfully avoiding the accident.

[0039] As shown in the figure, in use, it includes the pre-warning device starting, and then includes two routes: Figure 5 1. The rotary encoder senses the blade movement, the rotary encoder signal is processed, and the rotary encoder outputs a digital signal n1; 2. The linear encoder senses the anti-swing device movement, the linear encoder signal is processed, and the linear encoder outputs a digital signal n2; Then, the controller receives the dual-channel digital signal, the controller performs data processing and comparative analysis to determine whether the alarm threshold is exceeded, and if it is exceeded, the controller outputs an alarm signal for the staff or pilot to respond; if it is not exceeded, it continues to be monitored. The present application proposes to simultaneously monitor the "blade oscillation movement" and "anti-swing device working state" two key parameters to predict resonance, which are mutually confirmed, significantly improving the accuracy and reliability of prediction.

[0040] The abnormal state threshold based on the resonance precursor time window (such as 2 seconds) is established as the warning criterion, realizing the "advance" warning in the true sense, providing valuable time for disposal. The rotary encoder is integrated in the oscillation hinge, and the linear encoder is integrated in the anti-swing device, which is compact in structure, does not damage the original aerodynamic and mechanical structure, and is highly reliable.

[0041]

[0042] ​Variations or replacements within the technical scope of the present application can be easily conceived, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A helicopter resonance early warning device, characterized in that, include: A rotary encoder (2) is installed inside the oscillation hinge shaft of the rotor hub. Its bottom is fixed to the shaft, and its top knob (10) is connected to the helicopter rotor blade (3) through the connector (1). When the rotor blade (3) oscillates, it will drive the knob (10) to rotate. The rotary encoder converts the mechanical signal of the rotor blade's angular displacement into an electrical signal. A linear encoder (5) is installed inside a hydraulic damper (4) and includes a scale body (7) and a pull rod (8). The hydraulic damper (4) includes a housing (6) and a piston rod (9). The tail end of the scale body (7) is fixedly installed on the inner wall of the housing (6) by a bracket, and the front end of the pull rod (8) is hinged to the piston rod (9). The controller reads and processes the digital signals from the rotary encoder (2) and the linear encoder (5) in real time, compares the real-time signals with the preset threshold, and issues a warning.

2. The early warning device for helicopter resonance according to claim 1, characterized in that, The connector (1) is a connecting rod or coupling, and is made of high-strength aluminum alloy. One end of the connector (1) is connected to the knob (10), and the other end is connected to the root of the helicopter rotor blade (3).

3. The early warning device for helicopter resonance according to claim 1, characterized in that, The rotary encoder (2) is a hollow shaft absolute rotary encoder, and its inner diameter matches the size of the swing hinge shaft.

4. The early warning device for helicopter resonance according to claim 1, characterized in that, The linear encoder (5) is a magnetic grating linear encoder, and its range is greater than the maximum stroke of the piston rod (9).

5. The early warning device for helicopter resonance according to claim 1, characterized in that, The controller's main control chip is an industrial-grade ARM Cortex-M series MCU. The controller has a multi-channel encoder interface and a CAN bus interface for interconnection with the helicopter's airborne avionics system.

6. A method for early warning of helicopter resonance, based on the early warning device for helicopter resonance according to any one of claims 1 to 5, characterized in that, include: S1: The rotary encoder (2) detects the oscillation angle displacement change of the helicopter blade (3) in real time, generates and outputs a digital signal n1 to the controller; S2: The linear encoder (5) detects the linear displacement change of the piston rod (9) of the damper in real time, and generates and outputs the digital signal n2 to the controller; S3: The controller receives digital signals n1 and n2 and performs preprocessing such as filtering and noise reduction on the signals; The processed real-time data is compared with a preset threshold in the storage unit; S4: When either n1 or n2 exceeds its preset threshold, the controller immediately triggers the alarm device and issues a warning signal.

7. The early warning method for helicopter resonance according to claim 6, characterized in that, The threshold value corresponds to the critical value of the abnormal state when the rotor blade oscillation motion is drastically increased and the oscillation damper is working at high speed 2±0.5s before the helicopter resonates.

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