Tilt-rotor helicopter rotor state sensing system and measuring method

Abstract

The invention belongs to the field of tilt-rotor helicopter rotor state monitoring, and particularly relates to a tilt-rotor helicopter rotor state sensing system and a measurement method. Comprising six linear displacement sensors, an azimuth angle sensor, a collector ring and a processor, the six linear displacement sensors form a six-degree-of-freedom parallel platform, the lower end faces of the six linear displacement sensors are connected with the upper end face of an elastic universal hinge, and the upper end faces of the six linear displacement sensors are fixed to the upper end face of a rotor shaft; the azimuth angle sensor is mounted on the collector ring, the collector ring is mounted on the propeller hub, and the azimuth angle sensor measures the azimuth angle of the propeller hub support arm; output ends of the six linear displacement sensors and the azimuth angle sensor are connected with the processor; the onboard power supply system transmits direct current to the processor through the collector ring after direct current distribution.

Description

Technical Field

[0001] The present invention belongs to the field of tilt-rotor helicopter rotor state monitoring, and particularly relates to a tilt-rotor helicopter rotor state sensing system and a measurement method. Background Art

[0002] The tilt-rotor aircraft combines the advantages of helicopters and fixed-wing aircraft perfectly, and has the advantages of high speed, long range, large load capacity, small vibration, etc. The rotor of the tilt-rotor aircraft provides lift in the helicopter mode to overcome gravity and achieve maneuverable flight; in the fixed-wing mode, it provides thrust to overcome aerodynamic drag and achieve high-speed flight. To ensure that the tilt-rotor aircraft has good performance in all states, more stringent requirements are therefore imposed on its rotor. Due to the fact that the elastomeric gimbal can effectively solve problems such as rotor speed and load fluctuations and improve the aeroelastic stability of the whole aircraft, it thus has great application prospects on tilt-rotor aircraft.

[0003] The tilt-rotor aircraft with an elastomeric gimbal configuration mainly realizes the flapping and pitch change of the rotor through the deformation of the elastomeric bearing. During the pitch change process, the hub plane deflects relative to the rotor shaft. When the deflection angle of the hub is too large, it will not only cause a large dynamic load on the rotor elastomeric gimbal, but also the blade may collide with the airframe, resulting in extreme situations such as premature failure of the elastomeric gimbal or blade collision, thereby affecting flight safety. At present, there is no monitoring of the rotor hub state of this type of configuration helicopter. To ensure the flight safety of this type of helicopter, it is therefore necessary to obtain effective measured data of the hub deflection angle. Summary of the Invention

[0004] Object of the Invention: To provide a tilt-rotor helicopter rotor state sensing system and a measurement method for measuring the tilt-rotor helicopter rotor state of an elastomeric gimbal configuration hub.

[0005] Technical Solution:

[0006] A tilt-rotor helicopter rotor state sensing system includes: six linear displacement sensors, an azimuth sensor, a slip ring, and a processor. Among them,

[0007] Six linear displacement sensors are built to form a six-degree-of-freedom parallel platform. The lower end faces of the six linear displacement sensors are all connected to the upper end face of the elastomeric gimbal, and the upper end faces of the six linear displacement sensors are all fixed to the upper end face of the rotor shaft;

[0008] The azimuth sensor is installed on the slip ring, the slip ring is installed on the hub, and the azimuth sensor measures the azimuth angle of the hub arm;

[0009] The output ends of the six linear displacement sensors and the azimuth sensor are connected to the processor;

[0010] The on-board power supply system supplies power to the processor by transmitting direct current through the current collector ring after DC distribution; the sensors are powered after power conversion by the processor; the azimuth sensor is directly powered by the on-board power supply system;

[0011] The linear displacement signal, azimuth signal from the sensors and the clock signal from the flight control system are processed by the processor; the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane after processing are transmitted to the flight control system through the bus, so as to realize the real-time monitoring of the rotor state.

[0012] A method for measuring the rotor state of a tiltrotor helicopter, the method is executed by means of the above-mentioned tiltrotor helicopter rotor state perception system, and the method includes:

[0013] Step 1: Determine the relationship between the six-degree-of-freedom platform composed of linear displacement sensors and the hub state;

[0014]

[0015] R θ is the tilt angle of the rotor disk plane, is the azimuth angle of the normal vector of the rotor disk plane, that is, the angle between the projection of the normal vector on the oxy plane and the x-axis, is the azimuth angle of the normal vector of the rotor disk plane in the hub rotation coordinate system o1x1y1z1, is the azimuth angle corresponding to the x1 axis at time T in the hub rotation coordinate system o1x1y1z1, that is, the angle of rotation of the rotation coordinate system around the z-axis, Rx is the rotation around the x1 axis, and Ry is the rotation around the y1 axis;

[0016] Step 2: The clock signals of the on-board power supply and the flight control system are transmitted to the processor through the current collector ring to complete the self-check and data synchronization check of the processor and the sensors;

[0017] Step 3: During flight, collect the linear displacement sensor signal and azimuth signal and transmit them to the processor;

[0018] Step 4: The processor performs A / D conversion and filtering on the collected linear displacement sensor signal, and stores the filtered data to obtain effective time-domain data;

[0019] Step 5: According to the relationship between the six-degree-of-freedom platform and the hub state determined in Step 1, obtain the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane through relevant data processing algorithms;

[0020] Step 6: Transmit the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane calculated by the processor to the flight control system to complete the rotor state monitoring;

[0021] Step 7: Determine whether the tilt angle of the rotor disk plane in the flight control system exceeds the relevant angle limit value. When the tilt angle of the rotor disk plane exceeds the relevant angle limit value, adjust the flight attitude. After the adjustment is completed, repeat Steps 2 to 6. When the tilt angle of the rotor disk plane is within the relevant limit value, continue to fly without attitude adjustment.

[0022] Further, Step 3 also includes:

[0023] Before collecting data, it is necessary to calibrate the linear displacement sensor and the azimuth sensor.

[0024] Further, Step 5 is specifically: Determine the three translational quantities and three rotational quantities of the rotor disk plane according to the telescopic amounts of the six linear displacement sensors, and then determine the tilt angle of the rotor disk plane. According to the tilt angle of the rotor disk plane and the data of the azimuth sensor, the azimuth angle of the normal vector of the rotor disk plane can be obtained:

[0025]

[0026] A tilt-rotor helicopter rotor state perception system includes: three angular displacement sensors, an azimuth sensor, a slip ring, and a processor. Among them,

[0027] The three angular displacement sensors are installed between the elastic connecting rod and the central part, and are used to measure the rotation angle of the elastic connecting rod relative to the central part. Among them, the elastic connecting rod is connected to the central part of the hub through a connecting piece, and the intermediate gear of the central part is fixed on the rotor shaft;

[0028] The azimuth sensor is installed on the slip ring, the slip ring is installed on the hub, and the azimuth sensor measures the azimuth angle of the hub arm;

[0029] The output ends of the three angular displacement sensors and the azimuth sensor are connected to the processor;

[0030] The on-board power system transmits direct current to the processor through the slip ring after DC power distribution to realize the power supply of the processor; the sensors are powered after power conversion by the processor; the azimuth sensor is directly powered by the on-board power system;

[0031] The angular displacement signal, azimuth signal from the sensor and the clock signal of the flight control system are processed by the processor; the processed tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane are transmitted to the flight control system through the bus, so as to realize the real-time monitoring of the rotor state.

[0032] A tilt-rotor helicopter rotor state measurement method, which is executed by means of the above-mentioned tilt-rotor helicopter rotor state perception system. The method includes:

[0033] Step 1: Determine the relationship between the angular displacement sensor and the hub state;

[0034] Step 2: The clock signals of the airborne power supply and the flight management system are transmitted to the processor through the slip ring to complete the self-check of the processor and sensors and the data synchronization check.

[0035] Step 3: During flight, collect the angular displacement sensor signals and azimuth signals and transmit them to the processor.

[0036] Before collecting data, it is necessary to calibrate the angular displacement sensor and the azimuth sensor.

[0037] Step 4: The processor performs A / D conversion and filtering on the collected angular displacement sensor signals, and stores the filtered data to obtain effective time-domain data.

[0038] Step 5: According to the relationship between the six-degree-of-freedom platform or the angular displacement sensor and the hub state determined in Step 1, use relevant data processing algorithms to obtain the hub attitude angle information and the azimuth angle of the normal vector of the propeller disk plane.

[0039] Step 6: Transmit the hub attitude angle and the azimuth angle of the normal vector of the propeller disk plane calculated by the processor to the flight management system to complete the monitoring of the rotor state.

[0040] Step 7: In the flight management system, determine whether the tilt angle of the propeller disk plane exceeds the relevant angle limit value. When the tilt angle of the propeller disk plane exceeds the relevant angle limit value, adjust the flight attitude. After the adjustment is completed, repeat Steps 2 to 6 to monitor the rotor hub state after adjustment. When the tilt angle of the propeller disk plane is within the relevant limit value range, continue to maintain flight without attitude adjustment.

[0041] Further, in Step 1, the relationship between the angular displacement sensor and the hub state is:

[0042] The amplitude of the torsional angle of the elastic link is equal to the amplitude of the deflection angle of the elastic universal joint hub, and the phase values differ by a constant.

[0043] Further, Step 5 is specifically:

[0044] Perform spectral analysis on the three groups of RVDT data after filtering to obtain the amplitude and phase corresponding to 1Ω of each angular displacement sensor. Then compare the amplitude data corresponding to the three groups of angular displacement sensors, exclude abnormal data, and then solve the mean value of the normal data to obtain the hub attitude angle value.

[0045] Determine the azimuth angle of the normal vector of the propeller disk plane according to the phase corresponding to 1Ω.

[0046] Further, Step 5 is specifically:

[0047] Select the time-domain maximum amplitude and the corresponding moment T of the three groups of RVDT data after filtering; use the maximum amplitude as the tilt angle of the propeller disk plane.

[0048] Read the azimuth signal corresponding to the moment T, and use the azimuth signal corresponding to the moment T as the azimuth angle of the normal vector of the propeller disk plane.

[0049] Beneficial effects:

[0050] 1) This method uses two sensors to measure the rotor state, can realize real-time monitoring of the rotor state, and the measurement signals are accurate and effective, effectively avoiding the influence of factors such as light, climate, and electromagnetic interference during flight.

[0051] 2) In this method, the signals collected by the sensors can be preprocessed to ensure the accuracy of signal processing, and the signals are transmitted to the flight management system through the bus. The clock signal ensures good synchronization between the flight management system and the attitude angle.

[0052] 3) In this method, sensors, processors, and slip ring devices are used, all of which adopt an integrated design to ensure the minimum impact on the structure.

[0053] 4) This method derives the correlation between the angular displacement sensor signal and the hub attitude signal.

[0054] 5) The angular displacement sensor is convenient to connect, occupies a small space, is light in weight, has a fast dynamic response, a fast output rate, low cost, and has little impact on the entire rotor system.

[0055] 6) The technology maturity level of the angular displacement sensor method is high. This method indirectly measures the rotor attitude angle and avoids errors caused by directly measuring and introducing too many connecting devices.

[0056] 7) The technology maturity level of the linear displacement sensor method is high. This method directly measures through relevant connecting tooling, can monitor the rotor state in real time, and can measure the attitude angles of the rotor hub in various states.

[0057] 8) The processor can not only realize data processing, but also can add a storage device to store the original data, which is convenient for subsequent inspection and reprocessing of the data.

[0058] 9) The slip ring can effectively realize data transmission and azimuth signal transmission.

[0059] This method can not only realize real-time monitoring of the rotor state to ensure flight safety, but also verify the isochronism of the elastic universal joint through relevant signal data. Brief description of the drawings

[0060] Figure 1 It is a schematic diagram of a rotor state perception system for a tilt-rotor helicopter of the present invention.

[0061] Figure 2 It is a geometric simplified diagram of the hub structure;

[0062] Figure 3 It is a geometric simplified diagram at time T0;

[0063] Figure 4 The curve of the torsional angle of the elastic connecting rod bearing changing with time;

[0064] Figure 5 Schematic diagram of the coordinate system establishment and the distribution of hinge point positions;

[0065] Figure 6 It is a schematic diagram of a six-degree-of-freedom platform;

[0066] Figure 7 It is a schematic diagram of the state of the paddle disk. Specific implementation manners

[0067] To make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the implementation manners of this application will be described in more detail below with reference to the accompanying drawings in the implementation manners of this application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions from beginning to end. The described implementation manners are part of the implementation manners of this application, rather than all of the implementation manners. The implementation manners described below by referring to the accompanying drawings are exemplary and are intended to explain this application, and should not be construed as a limitation of this application. Based on the implementation manners in this application, all other implementation manners obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application. The implementation manners of this application will be described in detail below with reference to the accompanying drawings.

[0068] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "axial direction", "vertical", "upper", "lower", "upper end", "bottom end", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the protection scope of the present invention.

[0069] This article proposes a method for measuring the attitude of the rotor hub by using an angular displacement sensor (RVDT) / linear displacement sensor (LVDT) for the state monitoring of this type of helicopter hub.

[0070] This method uses the tilt angle R of the paddle disk plane for the hub attitude θ (the angle between the normal vector of the paddle disk tilt plane and the rotor axis) and the azimuth angle of the paddle disk where the normal vector of the paddle disk tilt plane is located Two parameters are described (these two parameters can be converted into the pitch angle and side chamfer required by the flight control system through relevant formulas), which is convenient for describing the hub attitude, such as Figure 7 shown.

[0071] This method uses an angular displacement sensor and a linear displacement sensor to measure the hub attitude angle simultaneously. When using an LVDT for measurement, a six-degree-of-freedom parallel platform is built using the linear displacement sensor. The lower end face of the linear displacement sensor is connected to the upper end face of the elastic universal hinge, and the upper end face of the linear displacement sensor is fixed to the upper end face of the rotor shaft. By the length change of 6 LVDTs and combined with the azimuth angle signal, the hub state can be obtained. When using an RVDT for measurement, the angular displacement sensor is installed between the elastic connecting rod and the central part. Through theoretical derivation and simulation analysis, the relationship between the rotation angle of the elastic connecting rod and the tilt angle of the hub plane is known, and then the hub attitude angle is indirectly measured. To ensure the safety of the aircraft attitude, the measured rotor hub state signal needs to be transmitted to the flight control system in time through the bus to adjust the aircraft attitude. In addition, to ensure the synchronization between the measured hub state and the adjustment of the flight control system, a clock signal needs to be transmitted. This method uses a linear displacement sensor / angular displacement sensor with higher measurement reliability and more accurate measurement signals, which can effectively avoid the influence of light, climate, etc. during flight. At the same time, this measurement method has the advantages of high precision, fast dynamic response, low cost, and strong anti-dynamic load ability.

[0072] The present invention proposes a rotor state perception system for a tilt-rotor helicopter for the rotor state of a hub with an elastic universal hinge configuration, such as Figure 1 . A linear displacement sensor / angular displacement sensor, a processor, a slip ring, and an azimuth angle sensor device are added to the elastic universal hinge hub structure to measure the corresponding signals, and then the attitude angle of the rotor hub of the tilt-rotor helicopter is obtained.

[0073] The rotor state perception system mainly includes signal acquisition, signal processing, and signal transmission. Signal acquisition mainly includes linear displacement data / angle data and slip ring azimuth angle signals; signal processing mainly processes the linear displacement / angle signals, azimuth angle signals from the sensors, and the clock signal of the flight control system through the processor; signal transmission is to transmit the processed tilt angle of the blade disk plane and the azimuth angle of the normal vector of the blade disk plane to the flight control system through the bus, so as to realize the real-time monitoring of the rotor state.

[0074] Relevant power supply information of each component: The on-board power system transmits direct current to the processor through the slip ring after DC distribution to supply power to the processor; the sensor is powered after power conversion by the processor; the azimuth angle sensor is directly powered by the on-board power system; the overall solution of the perception system is as Figure 1 shown.

[0075] The proposed rotor state perception system includes signal acquisition, signal processing, and signal transmission modules (integrating sensors, processors, slip rings, etc. into rotor state perception);

[0076] The rotor state can be described by the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane. The corresponding pitch angle of the flight control system can be obtained through theory and side chamfer

[0077] A six-degree-of-freedom parallel platform is constructed using six linear displacement sensors and 12 cross hinges. The attitude angle of the rotor hub is measured through contact measurement, and the measured rotor hub state is more comprehensive. It is proposed to form a six-degree-of-freedom parallel platform with six linear displacement sensors, such as Figure 6 Installed between the upper end face of the elastic universal hinge hub and the upper end face of the rotor shaft, it has the advantages of high precision, fast dynamic response speed, and effective measurement of the rotor state, effectively avoiding the ability to continue to maintain effective data measurement under external loads on the rotor.

[0078] The attitude angle of the rotor hub is indirectly measured using an angular displacement sensor. The angular displacement sensor measures the rotation angle of the elastic link bearing, which is convenient to install. Moreover, the angular displacement sensor is equipped with an eccentric compensation device to effectively eliminate the influence caused by other offset amounts;

[0079] The relationship between the torsional angle of the elastic link and the attitude angle of the rotor hub is established (there is a certain relationship between the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane);

[0080] Three groups of angular displacement sensors are symmetrically arranged, which can not only achieve mutual verification of data, but also effectively improve the output frequency of the attitude angle. In addition, the symmetric arrangement has less impact on the dynamic balance of the rotor;

[0081] To avoid large deviations between the measurement of the angular displacement sensor and the rotor attitude angle due to factors such as aerodynamic resistance, certain requirements are imposed on the stiffness of each direction of the elastic link bearing, and a corresponding compensation device is added to the angular displacement sensor to avoid the influence of angles in other directions on the measurement;

[0082] This linear displacement sensor measurement device can verify the constant speed performance of the elastic universal angle;

[0083] The angular distribution of the linear displacement sensors and the radius of the connection nodes at the upper and lower end faces affect the measurement angle range and spatial dimensions; (When the angular distribution of the linear displacement sensors and the cross angle distribution are unreasonable, jamming will occur within the deflection angle range; the radius of the connection nodes at the upper and lower end faces will have a certain impact on the measurement stroke and accuracy of the linear displacement sensors)

[0084] The tilt angle of the rotor disk plane is measured by the linear displacement sensor / angular displacement sensor, and the azimuth angle of the normal vector of the rotor disk plane can be obtained by combining the azimuth angle signal;

[0085] Based on the relevant processor, the attitude angle of the hub is calculated and fed back to the flight management system;

[0086] A method for measuring the rotor state of a tiltrotor helicopter, comprising:

[0087] Step 1: Determine the relationship between the six-degree-of-freedom platform composed of linear displacement sensors or the relationship between angular displacement sensors and the hub state;

[0088] The angular displacement sensor is installed between the elastic connecting rod and the central part to measure the torsional angle of the elastic connecting rod. By using the physical connection relationship, it can be deduced that the amplitude of the torsional angle of the elastic connecting rod is equal to the amplitude of the deflection angle of the elastic universal hinge hub, and the phase value differs by a constant;

[0089] The linear displacement sensors form a six-degree-of-freedom parallel platform to measure the angle between the upper end face of the elastic universal hinge and the fixed plane of the rotor shaft. The deflection attitude of the platform plane is solved by the change in the telescopic amount of the six linear displacement sensors;

[0090] The relationship between the six-degree-of-freedom platform composed of linear displacement sensors and the hub state is:

[0091]

[0092] R θ is the tilt angle of the rotor disk plane, is the azimuth angle of the normal vector of the rotor disk plane, that is, the angle between the projection of the normal vector on the fixed coordinate system oxy plane and the x-axis, is the azimuth angle of the normal vector of the rotor disk plane in the hub rotation coordinate system, is the azimuth angle corresponding to the x-axis of the hub rotation coordinate system at time T, that is, the angle of rotation of the rotation coordinate system around the z-axis. Rx is the rotation around the x1-axis, and Ry is the rotation around the y1-axis.

[0093] The azimuth angle sensor is installed on the slip ring, and the slip ring is installed on the hub. The azimuth angle sensor measures the azimuth angle of the hub arm;

[0094] Step 2: The clock signals of the airborne power supply and the flight management system are transmitted to the processor through the slip ring to complete the self-check and data synchronization check of the processor and the sensors;

[0095] The clock signal of the flight management system is transmitted to the processor through the slip ring, and then the self-check of the processor is carried out to ensure the effectiveness of the device. At the same time, the synchronization between the flight management system and the processor is achieved. In addition, the airborne power supply signal is transmitted to the processor to complete the power supply of the processor and the sensors;

[0096] Step 3: During flight, collect the signals of the linear displacement sensors or angular displacement sensors and azimuth angle signals, and transmit them to the processor;

[0097] Before collecting data, it is necessary to calibrate the angular displacement sensor, displacement sensor and azimuth sensor;

[0098] Step 4: The processor performs A / D conversion and filtering on the collected linear displacement sensor signal or angular displacement sensor signal, and stores the filtered data to obtain effective time-domain data;

[0099] Filtering: First, when the sampling rate of the angular displacement sensor is large, the amount of data obtained is large. Therefore, data processing such as averaging and smoothing can be performed on it, and then the data is resampled to facilitate the subsequent selection of the maximum and minimum values.

[0100] Step 5: According to the relationship between the six-degree-of-freedom platform or the angular displacement sensor and the hub state determined in Step 1, the tilt angle of the disk plane and the azimuth angle of the normal vector of the disk plane are obtained through relevant data processing algorithms; among them, the tilt angle of the disk plane is the angle between the normal vector of the hub plane and the axis of the rotor shaft, and the azimuth angle of the normal vector of the disk plane is the angle between the normal vector of the disk plane and the fuselage heading;

[0101] When solving the tilt angle of the disk plane according to the RVDT data, two methods can be used for processing,

[0102] Processing method 1: Perform spectral analysis on the three groups of filtered RVDT data respectively to obtain the amplitude and phase corresponding to 1Ω of each angular displacement sensor, then compare the amplitude data corresponding to the three groups of angular displacement sensors, exclude abnormal data, and then solve the mean value of the normal data to obtain the tilt angle value of the disk plane;

[0103] Determine the azimuth angle of the normal vector of the disk plane according to the phase corresponding to 1Ω;

[0104] Processing method 2: Select the maximum amplitude in the time domain and the corresponding moment T of the three groups of filtered RVDT data; use the maximum amplitude as the tilt angle of the disk plane,

[0105] Read the azimuth angle signal corresponding to moment T, and use the azimuth angle signal corresponding to moment T as the azimuth angle of the normal vector of the disk plane;

[0106] In step 5, the LVDT forms a six-degree-of-freedom parallel platform, and the data collected at each moment can be used to analyze the hub state. To ensure the validity of the data, data at multiple moments can be selected for analysis, and then the data is used for solution analysis to obtain the rotor state (the tilt angle information of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane). The following formula is repeatedly used for calculation to obtain the rotor state; when the rotor state is determined, the average of the moments T1 and T2 is taken to obtain the tilt angle of the rotor disk plane. To ensure the accuracy of the calculation, multiple time points can be selected for solution, and the desired hub state is obtained by averaging multiple sets of data. The corresponding azimuth angle is also inversely deduced using the time and azimuth angle signals;

[0107] Step 6: Transmit the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane calculated by the processor to the flight control system to complete the monitoring of the rotor state;

[0108] Step 7: In the flight control system, determine whether the tilt angle of the rotor disk plane exceeds the relevant angle limit value. When the tilt angle of the rotor disk plane exceeds the relevant angle limit value, adjust the flight attitude. After the adjustment is completed, repeat steps 2 to 6 to monitor the rotor hub state after adjustment. When the tilt angle of the rotor disk plane is within the relevant limit value range, continue to maintain flight without attitude adjustment.

[0109] An angular displacement sensor is installed on each arm, which can not only improve the data acquisition and the validity of the data, but also provide the signal output rate.

[0110] The method can be applied to the isokinetic performance measurement of elastic universal joints.

[0111] In step 1,

[0112] (1) Derivation of the relationship between the angular displacement sensor and the tilt angle of the rotor disk plane:

[0113] The angular displacement sensor is used to measure the torsional angle of the elastic connecting rod bearing (at the connection position of the central part), and is mainly composed of an angular displacement sensor, an eccentric compensation device and corresponding installation connectors.

[0114] 1.1 Parameter definition

[0115] Fixed coordinate system oxyz: A fixed coordinate system, with the coordinate origin o being the center of the sphere where the elastic universal joint is located, the x-axis parallel to the oncoming flow direction, the y-axis perpendicular to the x-axis, and the z-axis along the rotor axis direction;

[0116] θ: The angle between the axis of the hub plane and the x-axis;

[0117] β: The tilt angle of the rotor disk plane;

[0118] Ro: The transformation matrix between the coordinates after the rotor disk deflection and the fixed coordinate system;

[0119] R2: The radius of the circle where the elastic bearing is located;

[0120] N i : The bearing coordinates at the connection of the hub central component (the 1st bearing is the bearing near the hub arm 1);

[0121] N i ': The coordinates of the bearing at the connection of the hub central component after change;

[0122] M i : The bearing coordinates at the connection of the central component;

[0123] The torsional angle of the bearing at the central connection;

[0124] The torsional angle direction of the elastic bearing: Looking down from the outside of the central component to the hub center, the clockwise direction is positive and the counterclockwise direction is negative, that is, the elevation of the elastic link bearing relative to the propeller disk plane is positive, and the depression of the elastic link bearing relative to the propeller disk plane is negative;

[0125] 1.2 Geometric relationship

[0126] The elastic universal hinge moves around the center of the spherical elastic bearing to achieve the transmission of centrifugal force and flapping motion. The following gives the simplified model of the elastic universal hinge, where the position of the universal hinge center is the coordinate origin, and the initial elastic bearing center is in the xoy plane, as Figure 2 .

[0127] 1.3 Derivation of angle relationship

[0128] 1.3.1 Derivation of amplitude relationship

[0129] The hub central component rotates around the center o, then it can be equivalent to the rotation of bearings N1, N2, and N3 around a certain straight line passing through the center o in the xoy plane. The transformation matrix between the coordinates of the propeller disk after deflection and the fixed coordinate system is as follows:

[0130]

[0131] In the fixed coordinate system, the bearing coordinates N1, N2, and N3 at the connection of the hub central component are:

[0132]

[0133] After the hub plane deflects, the coordinates of the bearing after change:

[0134] [N′1 N′2 N′3] = Ro[N1 N2 N3]

[0135] In the fixed coordinate system, the bearing coordinates M1, M2, and M3 at the connection of the central component are:

[0136]

[0137] After the hub plane deflects, the bearing change coordinates:

[0138] [N′1 N′2 N′3] = Ro[N1 N2 N3]

[0139] In the fixed coordinate system, the bearing coordinates M1, M2, M3 at the connection of the central part are:

[0140]

[0141] The torsional angle of the bearing at the central connection Can be considered as the vector With the linear plane angle of the plane xoy, so:

[0142]

[0143] Taking the No. 1 bearing as an example and substituting the relevant coordinate data, we can get:

[0144]

[0145] Considering that the actual blade disk inclination angle is small, making the approximation of sinβ≈0 and cosβ≈1, and then simplifying to get:

[0146]

[0147] From the above formula, we can know:

[0148] That is

[0149] When θ = 0, cosθ = 1, so:

[0150] That is

[0151] Therefore, the blade disk inclination angle β and the torsional angle of the elastic bearing Have equal amplitudes.

[0152] 1.3.2 Derivation of the phase relationship

[0153] Below Figure 3 Give the geometric simplification diagram at time T0.

[0154] Direction definition: Looking down from the outside of the central part to the hub center, the clockwise direction is positive and the counterclockwise direction is negative, that is, the elastic link bearing rising relative to the blade disk plane is positive, and the elastic link bearing lowering relative to the blade disk plane is negative.

[0155] Since the motion law of the elastic universal hinge in the rotating coordinate system is mainly a sine curve at the first-order rotation frequency. The variation curve of the torsional angle of the elastic connecting rod bearing is the same as that of the elastic universal hinge. Figure 4 Give the curve of the torsional angle of the elastic connecting rod bearing changing with time.

[0156] When the rotor state is stable, the tilt angle of the blade disk is fixed relative to the position of the fixed coordinate system. In the fixed coordinate system, the attitude of the rotor can be described by the tilt angle of the blade disk plane and the azimuth angle of the normal vector of the blade disk plane. Assume the attitude angle of the blade disk is:

[0157] β = 10°

[0158]

[0159] Note: For the convenience of description, the unit of the plane tilt angle is (°) and the unit of the azimuth angle is (rad).

[0160] At t = 0, the azimuth angle of bearing M1 is -π / 3 and the plane tilt angle is 10°:

[0161]

[0162] At t = 0, the azimuth angle of bearing M2 is π / 3 and the amplitude of the deflection angle is -5°:

[0163]

[0164] At t = 0, the azimuth angle of bearing M3 is π and the amplitude of the deflection angle is -5°:

[0165]

[0166] From Figure 4 It can be seen that at the azimuth angle of -π / 3, the rotation of bearing M1 reaches the positive maximum, and the structural angle between this bearing M1 and the hub arm is π / 3. The difference between the azimuth angle corresponding to the maximum tilt angle of the blade disk plane and the azimuth angle corresponding to the maximum positive torsional angle of the elastic connecting rod bearing M1 is the structural angle between the elastic connecting rod bearing M1 and the hub arm. Therefore, the difference between the azimuth angle corresponding to the maximum torsional angle of the elastic connecting rod bearing and the azimuth angle corresponding to the maximum tilt angle of the blade disk plane is constant.

[0167] When the structural angle changes, the difference in the azimuth angle changes.

[0168] (2) Linear displacement sensor:

[0169] 2.1 Parameter definition

[0170] Coordinate system oxyz: Fixed coordinate system, the origin o of the coordinate is the center of the sphere where the elastic universal hinge is located, the x-axis is parallel to the oncoming flow direction, the y-axis is perpendicular to the x-axis, and the z-axis is along the rotor axis direction;

[0171] Coordinate system o1x1y1z1: A rotating coordinate system with the origin o1 being the center of the upper end face of the fairing. The plane o1x1y1z1 is parallel to the upper end face of the fairing. The coordinate system o1x1y1z1 rotates only about the z-axis (rotor axis) relative to the coordinate system oxyz.

[0172] Coordinate system o’x’y’z’: A moving coordinate system with the origin o’ at the center of the upper end face of the spherical elastic bearing. The plane o’x’y’ is parallel to the upper end face of the spherical elastic bearing. The moving coordinate system moves with the motion of the spherical elastic bearing.

[0173] A j : The coordinates of the upper hinge point of the linear displacement sensor in the rotating coordinate system.

[0174] B j : The coordinates of the lower hinge point of the linear displacement sensor in the rotating coordinate system.

[0175] h a : The height of the upper hinge point of the linear displacement sensor from the plane o1x1y1z1 of the rotating coordinate system.

[0176] h b : The height of the lower hinge point of the linear displacement sensor from the plane o’x’y’z’ of the moving coordinate system.

[0177] R a : The radius of the distribution circle of the upper hinge point of the linear displacement sensor.

[0178] R b : The radius of the distribution circle of the lower hinge point of the linear displacement sensor.

[0179] α: Half of the included angle between two adjacent upper hinge points of the linear displacement sensor (half of the included angle between o1A j1 and o1A j2 ).

[0180] β: Half of the included angle between two adjacent lower hinge points of the linear displacement sensor (half of the included angle between o’B j1 and o’B j2 ).

[0181] Q = (Rx, Ry, Rz, Dx, Dy, Dz): The pose of the moving coordinate system relative to the rotating coordinate system. Rx is the rotation about the x1-axis, Ry is the rotation about the y1-axis, Rz is the rotation about the z1-axis, Dx is the translation along the x1-axis, Dy is the translation along the y1-axis, and Dz is the translation along the z1-axis.

[0182] θ x : The transformation matrix for rotation about the x1-axis (the moving coordinate system rotates about the x1-axis relative to the rotating coordinate system).

[0183] θy : Transformation matrix for rotation about the y1 axis (the moving coordinate system rotates about the y1 axis relative to the rotating coordinate system);

[0184] θ z : Transformation matrix for rotation about the z1 axis (the moving coordinate system rotates about the z1 axis relative to the rotating coordinate system);

[0185] R: Transformation matrix from the data of the moving coordinates to the rotating coordinate system;

[0186] l j0 : Initial length of each moving rod (linear displacement sensor);

[0187] Δl j : Expansion and contraction amount of each moving rod (linear displacement sensor);

[0188] 2.2 Model Simplification

[0189] To clearly describe the movement of the six-degree-of-freedom platform in three-dimensional space, three reference coordinate systems are selected: the fixed coordinate system oxyz, the rotating coordinate system o1x1y1z1, and the moving coordinate system o’x’y’z’, and 12 hinge points, as Figure 5 shown.

[0190] 2.3 Relationship Deduction

[0191] From Figure 5 geometric relationship, the coordinates of the upper hinge point in the rotating coordinate system can be obtained:

[0192]

[0193] The elements from the 1st row to the 3rd row of the j-th column in Equation 1) represent the coordinates of the upper hinge point Aj in the rotating coordinate system.

[0194]

[0195] The elements from the 1st row to the 3rd row of the j-th column in Equation 2) represent the coordinates of the lower hinge point Bj in the moving coordinate system.

[0196]

[0197] Transformation matrix from the moving coordinate system to the rotating coordinate system:

[0198]

[0199] According to Equation 2) and Equation 4), we can obtain:

[0200] P = [p ij 4×6 = R·B 5)

[0201] In Equation 5), P is the coordinate matrix of the lower hinge point in the rotating coordinate system, p​ij It is the coordinate corresponding to the coordinate transformation of the lower hinge point in the moving coordinate system to the rotating coordinate system.

[0202] When the telescopic amounts of the six moving rods are known, the corresponding pose Q of the moving platform can be solved, that is, solving Q when Δl j is known. Therefore, the forward kinematics problem of the six-degree-of-freedom parallel platform can be regarded as a data problem of solving the position parameter Q with the known parameter Δl j , and the equation is as follows:

[0203]

[0204] Solve the system of equations (6), and the pose Q can be obtained:

[0205]

[0206] First, perform a Taylor series expansion of the nonlinear system of equations (7) around Q0 and take its linear part to transform the nonlinear system of equations into a linear system of equations, that is:

[0207]

[0208] Let ΔQ = Q - Q0, where Δq j = q j - q j0 (j = 1, 2,..., 6), then we get:

[0209]

[0210] Regard Equation (9) as a linear system of equations with Q as the unknown, and its coefficient matrix J is:

[0211]

[0212] J is the Jacobian matrix, then Equation (9) can be simplified to:

[0213]

[0214] The specific steps to solve this linear equation are as follows:

[0215] a) Input the structural parameters of the platform and the telescopic amounts of each moving rod, and select the attitude of the platform at the middle position as the initial value of iteration;

[0216] b) Determine f j (Q0) based on the telescopic amounts of each moving rod calculated by the given initial value, and obtain the Jacobian matrix J;

[0217] c) Use Equation (11) above to solve the forward kinematics;

[0218] d) Given the accuracy, judge max(Δqi ) ≤ σ. If the given accuracy requirement is met, output the result; otherwise, use the formula Δq i = q i - q i0 to correct the pose, and repeat steps 2) - 6) until the solution accuracy is satisfied.

[0219] The above numerical method for solving the nonlinear equations can be called the Newton - Taylor expansion method. Since the moving platform generally operates near the middle position, the initial value of the positive solution in the algorithm is set as the pose when the moving platform is in the middle position, which ensures the convergence of the algorithm and makes the convergence speed faster. Different from other numerical methods, in each step of the solution procedure, the formula of this algorithm has an analytical form. The key to using this method is to obtain the coefficient matrix J. The solution of the Jacobian matrix J is given below.

[0220] Taking the partial derivatives of the above formula (7) gives:

[0221]

[0222] From formula (5), it can be seen that

[0223]

[0224] Through the above solution, the angular change of the moving coordinate system relative to the rotating coordinate system can be obtained. Therefore, a certain coordinate transformation is required to convert the angle in the rotating coordinate system to the fixed coordinate system.

[0225] Since the hub plane tilt angle is in the small - angle range, the formula for the tilt angle of the propeller disk plane is:

[0226]

[0227] R θ is the tilt angle of the propeller disk plane, is the azimuth angle of the normal vector of the propeller disk plane, that is, the angle between the projection of the normal vector on the oxy plane and the x - axis, is the azimuth angle of the normal vector of the propeller disk plane in the hub rotating coordinate system, is the azimuth angle corresponding to the x - axis of the hub rotating coordinate system at time T (i.e., the angle of rotation of the rotating coordinate system around the z - axis).

Claims

1. A tilt-rotor helicopter rotor state perception system, characterized in that, Including: Six linear displacement sensors, an azimuth sensor, a slip ring, and a processor. Among them, The six linear displacement sensors form a six-degree-of-freedom parallel platform. The lower end faces of the six linear displacement sensors are all connected to the upper end face of the elastic universal hinge, and the upper end faces of the six linear displacement sensors are all fixed to the upper end face of the rotor shaft; The azimuth sensor is installed on the slip ring, and the slip ring is installed on the hub. The azimuth sensor measures the azimuth angle of the hub arm; The output ends of the six linear displacement sensors and the azimuth sensor are connected to the processor; The on-board power system transmits direct current to the processor through the slip ring after direct current distribution to realize the power supply of the processor; the sensors are powered after power conversion by the processor; the azimuth sensor is directly powered by the on-board power system; The linear displacement signals, azimuth signals from the sensors and the clock signal of the flight management system are processed by the processor; the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane after processing are transmitted to the flight management system through the bus, so as to realize the real-time monitoring of the rotor state.

2. A method for measuring the rotor state of a tilt-rotor helicopter, characterized in that, The method is executed by means of the tilt-rotor helicopter rotor state perception system described in claim 1. The method includes: Step 1: Determine the relationship between the six-degree-of-freedom platform composed of linear displacement sensors and the hub state; R θ is the tilt angle of the propeller disk plane, is the azimuth angle of the normal vector of the propeller disk plane, that is, the angle between the projection of the normal vector on the oxy plane and the x-axis, is the azimuth angle of the normal vector of the propeller disk plane in the hub rotation coordinate system o1x1y1z1, is the azimuth angle corresponding to the x1 axis at time T in the hub rotation coordinate system o1x1y1z1, that is, the angle of rotation of the rotation coordinate system around the z-axis, Rx is the rotation around the x1 axis, and Ry is the rotation around the y1 axis; Step 2: The on-board power supply and the clock signal of the flight management system are transmitted to the processor through the slip ring to complete the self-check and data synchronization check of the processor and the sensors; Step 3: During flight, collect the linear displacement sensor signals and azimuth signals and transmit them to the processor; Step 4: The processor performs A / D conversion and filtering on the collected linear displacement sensor signals, and stores the filtered data to obtain effective time-domain data; Step 5: According to the relationship between the six-degree-of-freedom platform and the hub state determined in Step 1, obtain the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane through relevant data processing algorithms; Step 6: Transmit the tilt angle of the rotor disk plane and the azimuth angle of the normal vector of the rotor disk plane calculated by the processor to the flight management system to complete the rotor state monitoring; Step 7: Judge whether the tilt angle of the rotor disk plane exceeds the relevant angle limit value in the flight management system. When the tilt angle of the rotor disk plane exceeds the relevant angle limit value, adjust the flight attitude. After the adjustment is completed, repeat Steps 2 to 6. When the tilt angle of the rotor disk plane is within the relevant limit value range, continue to fly without attitude adjustment.

3. The method for measuring the rotor state of a tilt-rotor helicopter according to claim 2, wherein Step 3 also includes: Before collecting data, it is necessary to calibrate the linear displacement sensor and the azimuth sensor.

4. The tilt-rotor helicopter rotor state measurement method according to claim 2, characterized in that, Step 5 is specifically: Determine the three translational quantities and three rotational quantities of the rotor disk plane according to the telescopic amounts of the six linear displacement sensors, and then determine the tilt angle of the rotor disk plane. According to the tilt angle of the rotor disk plane and the data of the azimuth sensor, the azimuth angle of the normal vector of the rotor disk plane can be obtained:

5. A rotor state sensing system for a tiltrotor helicopter, characterized in that, Including: Three angular displacement sensors, an azimuth sensor, a slip ring, and a processor. Among them, The three angular displacement sensors are installed between the elastic connecting rod and the central member to measure the rotation angle of the elastic connecting rod relative to the central member. Among them, the elastic connecting rod is connected to the hub central member by means of a connecting member, and the intermediate gear of the central member is fixed on the rotor shaft; The azimuth sensor is installed on the slip ring, the slip ring is installed on the hub, and the azimuth sensor measures the azimuth of the hub arm; The output ends of the three angular displacement sensors and the azimuth sensor are connected to the processor; The on-board power system transmits direct current to the processor through the slip ring after DC power distribution to supply power to the processor; the sensors are powered after power conversion by the processor; the azimuth sensor is directly powered by the on-board power system; The angular displacement signals, azimuth signals from the sensors and the clock signal of the flight control system are processed by the processor; the tilt angle of the rotor disk plane and the azimuth of the normal vector of the rotor disk plane after processing are transmitted to the flight control system through the bus, so as to realize the real-time monitoring of the rotor state.

6. A method for measuring the rotor state of a tiltrotor helicopter, characterized in that, The method is executed by means of the rotor state perception system of the tilt-rotor helicopter described in claim 5, and the method includes: Step 1: Determine the relationship between the angular displacement sensor and the hub state; Step 2: The on-board power supply and the clock signal of the flight control system are transmitted to the processor through the slip ring to complete the self-check and data synchronization check of the processor and the sensors; Step 3: During flight, collect the angular displacement sensor signals and azimuth signals and transmit them to the processor; Before collecting data, it is necessary to calibrate the angular displacement sensor and the azimuth sensor; Step 4: The processor performs A / D conversion and filtering on the collected angular displacement sensor signals, and stores the filtered data to obtain effective time-domain data; Step 5: According to the relationship between the six-degree-of-freedom platform or the angular displacement sensor and the hub state determined in Step 1, obtain the hub attitude angle information and the azimuth of the normal vector of the rotor disk plane through relevant data processing algorithms; Step 6: Transmit the hub attitude angle and the azimuth of the normal vector of the rotor disk plane calculated by the processor to the flight control system to complete the rotor state monitoring; Step 7: Judge whether the tilt angle of the rotor disk plane exceeds the relevant angle limit value in the flight control system. When the tilt angle of the rotor disk plane exceeds the relevant angle limit value, adjust the flight attitude. After the adjustment is completed, repeat Steps 2 to 6 to monitor the rotor hub state after adjustment. When the tilt angle of the rotor disk plane is within the relevant limit value, continue to maintain the flight without attitude adjustment.

7. The method for measuring the rotor state of a tilt-rotor helicopter according to claim 6, wherein In Step 1, the relationship between the angular displacement sensor and the hub state is: The amplitude of the torsional angle of the elastic connecting rod is equal to the amplitude of the deflection angle of the elastic universal hinge hub, and the phase value differs by a constant.

8. The tilt-rotor helicopter rotor state measurement method according to claim 6, characterized in that Step 5 is specifically: Perform spectral analysis on the three groups of RVDT data after filtering respectively to obtain the amplitude and phase corresponding to 1Ω of each angular displacement sensor, then compare the amplitude data corresponding to the three groups of angular displacement sensors, exclude abnormal data, and then solve the mean value of the normal data to obtain the hub attitude angle value; Determine the azimuth of the normal vector of the rotor disk plane according to the phase corresponding to 1Ω.

9. The method for measuring the rotor state of a tilt-rotor helicopter according to claim 6, wherein Step 5 is specifically: Select the maximum amplitude in the time domain and the corresponding moment T of the three groups of RVDT data after filtering; Take the maximum amplitude as the tilt angle of the rotor disk plane; Read the azimuth signal corresponding to the moment T, and take the azimuth signal corresponding to the moment T as the azimuth of the normal vector of the rotor disk plane.

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