Telemetering system and method with top trigger signal cascading synchronization

Abstract

The application belongs to the technical field of helicopter rotor test, and discloses a telemetry system and method with TOP trigger signal cascade synchronization. The system comprises a wireless module, a Beidou signal switching module, an acquisition module, a circuit board, a battery, an upper computer, a sensor assembly, a non-rotating table body and a device shell. The rotor system is arranged on the non-rotating table body, and the device shell is arranged above the hub of the rotor system. The circuit board is arranged at the opening of the device shell, and the battery is connected below the circuit board. The wireless module, the Beidou signal switching module and the acquisition module are connected above the circuit board. The sensor assembly is arranged on the rotor system and connected with the acquisition module through a cable. The Beidou signal switching module is used for receiving a Beidou signal. The wireless module is used for communicating with the upper computer.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helicopter rotor test, and particularly relates to a telemetry system and method with TOP trigger signal cascade synchronization. BACKGROUND

[0002] In the ground test or flight test of a helicopter rotor, the dynamic characteristics of the rotor need to be analyzed, and therefore the rotation signals on the blades and the rotating shaft need to be collected and monitored. In the conventional rotor test, a preamplifier plus a current collection ring is usually used. This method is complex in system construction, has large signal noise interference, and with the new trend of the development of electrically driven aircraft, the rotor is small in size and compact in structure, and there is no transmission shaft of the traditional conventional rotor, so that the current collection ring cannot be installed, which results in that the rotation signal data, including the flapping, oscillation and torsional load of the rotor blade, the tension, torque and bending moment load of the rotor shaft, cannot be collected in many electrically driven rotor tests, and cannot provide strong support for the design. SUMMARY

[0003] The application aims at the particularity of the electrically driven rotor structure, the inability to install the conventional current collection ring device to collect the rotation load signal and the TOP signal, and proposes a telemetry system and method with TOP trigger signal cascade synchronization. The weight of the whole telemetry system is 600g, the size is diameter D*height H=120mmX60mm, and the telemetry system can be conveniently and quickly installed on a small or medium-sized electrically driven rotor hub. The rotation load signals of the blades, the rotor shaft and the like are collected, the rotation speed TOP signal is collected at the same time, multiple telemetry systems can be cascade synchronized, the synchronous data analysis in the multi-rotor test is ensured, the collected signal data can be stored in the system locally, the rotation signal data can be transmitted wirelessly to realize the real-time monitoring and storage of the rotation signal data on the host computer, the telemetry collection system supports offline collection and post-recovery, and the data analysis is facilitated.

[0004] TECHNICAL SCHEME

[0005] A telemetry system with TOP trigger signal cascade synchronization comprises a wireless module, a Beidou signal switching module, a collection module, a circuit board, a battery, a host computer, a sensor assembly, a non-rotating table body and a device shell.

[0006] The rotor system is arranged on the non-rotating table body, and the device shell is arranged above the hub of the rotor system. The circuit board is arranged at the opening of the device shell, and the battery is connected below the circuit board. The wireless module, the Beidou signal switching module and the collection module are connected above the circuit board.

[0007] The sensor assembly is arranged on the rotor system and connected to the collection module through a cable. The Beidou signal switching module is used for receiving the Beidou signal. The wireless module is used for communicating with the host computer.

[0008] The sensor assembly comprises a load measuring assembly and a rotating speed measuring assembly.

[0009] The acquisition module acquires the rotating blade flap load, the rotating blade edgewise load, the rotating shaft tension load and the rotating speed pulse signal.

[0010] The host computer sets the rotating speed pulse signal acquisition period T = 0.1s, and the number of high level pulses acquired in T is recorded as k.

[0011] If k < 2, T is assigned as T + 0.05s, and the rotating speed is measured by the end period method until k >= 2.

[0012] If k >= 2, the rotating blade flap load, the rotating blade edgewise load and the rotating shaft tension load are subjected to FFT analysis to obtain the first five main peak frequencies within 200Hz of the three load signals, the first five main peak frequencies of the blade flap load are H = [H1 H2 H3 H4 H5], the first five main peak frequencies of the blade edgewise load are B = [B1 B2 B3 B4 B5], and the first five main peak frequencies of the rotor shaft tension load are T = [T1 T2 T3 T4 T5], and a 15-element matrix HBT = [H1 H2 H3 H4 H5 B1 B2 B3 B4 B5 T1 T2 T3 T4 T5] is formed.

[0013] The elements of the HBT matrix are traversed, and if two frequencies X and Y exist in the matrix and satisfy Y = S * X, X element-of HBT, Y element-of H and Y element-of B and Y element-of T, the rotating speed R = X * 60.

[0014] Further, the system further comprises an outdoor receiving antenna, a Beidou relay module and an indoor transmitting antenna. In the wind tunnel test, the outdoor Beidou signal is introduced into the indoor to facilitate the remote telemetry equipment to receive the Beidou clock signal through the Beidou signal switching module. The flap, edgewise, torsion and rotating speed signals on the blades in the rotor system are connected through the cable and the acquisition module of the remote telemetry system to acquire the load signals. The switch and the wireless AP mainly receive the data signals transmitted by the remote telemetry system through the wireless module. The wireless transmission is through the WiFi mode, uses the 2.4GHz frequency band, realizes the point-to-point wireless communication between the AP base station and the remote telemetry system terminal, uses the Ethernet protocol as the core in the link layer to realize the addressing and checking of the information transmission, realizes the multi-system wireless networking of the communication distance of at least 100 meters, and the wireless transmission stability is that the number of data packet / data frame loss per hour is less than or equal to 3. The wireless AP further transmits the data to the host computer through the switch and the network cable for storage, processing and analysis.

[0015] Further, the device shell is an open-top cylindrical shell; the device shell is mounted on the hub through an intermediate adapter. The cylinder has better symmetry, the connection with the intermediate adapter is reasonable in design, and has reliable anti-loosening measures. At the same time, it has anti-vibration and anti-impact design, which meets the requirements of the test bench vibration and impact use environment.

[0016] Further, the load measuring assembly is a Wheatstone full bridge pasted on the blade. Its schematic diagram is shown in Figure 4, wherein Vi+, Vi- are bridge output voltages, and Eg+, Eg- are bridge excitation voltages. 1) Input mode selection: the channel can realize strain full bridge and voltage (thermocouple) and different input mode selection through program-controlled internal relay switching; 2) range switching: the required gain of each grade is realized through program-controlled gain switching, and a gain-switchable instrument amplifier is used to ensure each gain grade; 3) low-pass filtering: the low-pass filtering cutoff frequency can be set to meet the demand of 2k frequency response of the measured signal and to ensure the signal-to-noise ratio; 4) single-ended to differential: the single-ended signal is converted into a differential signal for 16-bit ADC acquisition; 5) bridge voltage: multi-grade bridge voltage switching is realized through DA switching.

[0017] Further, the rotational speed measuring assembly comprises: an optical sensor and a reflective sticker;

[0018] The optical sensor is installed on the side wall of the intermediate adapter;

[0019] The reflective sticker is pasted on the non-rotating table body and located directly below the optical sensor.

[0020] Further, the mass center of the whole composed of the intermediate adapter, the device shell and all the devices carried by the device shell coincides with the rotational center of the rotor system; the circuit board and the devices carried on the circuit board are symmetrically arranged according to the rotational center of the rotor system; the wireless module, the Beidou signal adapter module and the acquisition module are designed in a centrally symmetric arrangement; a trimming structure is designed on the circuit board to compensate for the mass eccentricity of the circuit board; the installation position and mass of the trimming structure are obtained through simulation; the circuit board is uniformly provided with threaded holes at the circumferential edge, and mass blocks are installed on the threaded holes to eliminate the mass eccentricity caused by processing and installation errors.

[0021] The installation orientation and mass of the counterweight are calculated as follows:

[0022] Step a: define the high pulse trigger point of the rotational speed pulse signal as the zero phase point, record the phase difference of the first-order fundamental frequency signal of a load of the blade relative to the zero phase point as Φ1, and record the amplitude as A1, then the initial vector point of the load is D1(A1, Φ1);

[0023] Step b: install the mass of m in any threaded hole, the mass of m is at the phase of Φ relative to the zero phase point, calculate the phase angle of the first order fundamental frequency signal relative to the zero phase point again, the amplitude is A2, and record as D2(A2, Φ2);

[0024] Step c: D2-D1=D3(A3, Φ3), D3 is the influence of the mass of m on the dynamic balance at the phase of Φ;

[0025] The amplitude of the influence is A3, and the phase is Φ0=Φ-Φ3, the unit mass influence load amplitude A3 / m, and the mass influence phase leads Φ0;

[0026] Step d: according to D3, the initial load D1(A1, Φ1) is balanced, and the balancing dynamic balance needs to load the mass m' = A1*A3 / m at the phase Φ'=Φ1-Φ0.

[0027] The circuit and mounting structure design of all rotating parts adopts a central symmetric arrangement in the design, and the circuit board and components are arranged as symmetrically as possible around the shaft center;

[0028] The circuit arrangement can minimize the mass eccentricity, and the remaining torque that cannot be balanced by the circuit arrangement is balanced by the structure design. The structure design fits the mass eccentricity caused by the circuit arrangement through simulation, and balances the mass eccentricity through structure design, so as to ensure that the mass center coincides with the rotation center after the design is completed.

[0029] Further, the circuit board is a multi-layer circuit board, which is sequentially arranged from top to bottom as top layer, power ground layer, power layer, signal layer, +15V power supply layer and bottom layer, and the power layer is large area copper clad;

[0030] The circuit board design reasonably partitions the power ground layer, the power layer and the signal layer, and the power layer is large area copper clad. After multiple tests and comparisons, the reasonable design of suppressing interference with the smallest ground impedance and the smallest circuit noise is found. The components are reasonably arranged, the electromagnetic disturbance sources such as digital and CPU clock generators are shielded and isolated, and the components are simulated. The connector and its pins are placed on one side of the printed board and away from high-speed devices, which effectively suppresses the common mode current radiation. The sensitive components are partitioned and away from the electromagnetic disturbance sources in the design of the printed board.

[0031] The ground lines for the power supply voltage, digital circuits, and analog circuits are separated. Experimentation has also identified the optimal location for short-circuiting the different ground lines. By reducing the characteristic impedance of the power supply line and using filtering and decoupling capacitors, the information acquisition equipment effectively suppresses electromagnetic interference radiated into space by transient power supply currents and common impedance coupling interference caused by power supply line inductance. Incompatible signal lines are kept away from each other, with multiple layers routed perpendicularly to each other to reduce electric and magnetic field coupling interference between signal lines. High-speed signal lines are rationally positioned, using the shortest routing method and shielding measures to avoid interference with other signal lines.

[0032] A telemetry method with cascade synchronization of TOP trigger signals is provided, the method being implemented based on the system and comprising the following steps:

[0033] 1) Install the lightweight telemetry system and turn on the power;

[0034] 2) According to the test requirements, set the parameters, including: range, filter, input mode, bridge mode, and sampling frequency;

[0035] 3) When multiple lightweight telemetry systems are required to collect data synchronously, check whether Beidou communication is normal;

[0036] 4) If synchronous acquisition is not required or BeiDou signals cannot be received, the internal clock of the lightweight telemetry system is directly used for signal acquisition;

[0037] Collect the flapping load of the rotating blade, the shimmying load of the rotating blade, and the tensile load of the rotating shaft; collect the speed pulse signal; and calculate the speed as follows:

[0038] Step 1: Given a speed pulse signal acquisition period T = 0.1s, the number of speed high-level pulses collected within T time is recorded as k;

[0039] Step 2: If k < 2, jump to step 3; if k ≥ 2, jump to step 6;

[0040] Step 3: T=T+0.05s;

[0041] Step 4: Determine whether k is greater than or equal to 2. If so, jump to step 5, otherwise return to step 3;

[0042] Step 5: k-1 complete rotor rotations are collected within time T, with an incomplete low-level pulse data segment at the beginning and end. These data are stored in the matrix in the form of specific digital points. The total number of points between the last two high-level pulses in the matrix is ​​defined as n.

[0043] Let the total number of points from the beginning of the entire T time domain S to the first high level of the entire T time domain be n1; let the total number of points from the first high level of the entire T time domain to the end E be n2; then in the entire T time domain, the rotor rotates a total of turns;

[0044] Obtain the rotor speed ;

[0045] Step six: perform FFT analysis on the rotating blade flapping load, rotating blade edgewise load, and rotating shaft tension load to obtain the first five main peak frequencies within 200Hz of the three load signals, the first five main peak frequencies of the blade flapping load are H = [H1H2 H3 H4 H5], the first five main peak frequencies of the blade edgewise load are B = [B1 B2 B3 B4 B5], and the first five main peak frequencies of the rotor shaft tension load are T = [T1 T2 T3 T4 T5], forming a 15-element matrix HBT = [H1 H2 H3 H4 H5 B1 B2 B3 B4 B5 T1 T2 T3 T4 T5];

[0046] Step seven: traverse the HBT matrix elements, if there are two frequencies X and Y in them that satisfy Y = S * X, X ∈ HBT, Y ∈ H and Y ∈ B and Y ∈ T, then the speed R = X * 60;

[0047] 5) All speed signal sampling data are transmitted to the host computer in real time for display processing, analysis, and network data distribution;

[0048] 6) After the test is completed, send a stop command to stop sampling.

[0049] Further, the speed signal acquisition process is as follows:

[0050] The speed signal collected when the photoelectric sensor is triggered is a 10V high level pulse signal, and the voltage value collected when it is not triggered is 0V low level.

[0051] The end cycle speed measurement method measures the cycle time T, and the number of high level pulses collected in T is k, which is k-1 complete rotor rotations, and there is a segment of incomplete low level pulse data at the beginning and end; these data are saved in the matrix in the form of specific digital points, and at this time the total number of points between the last two high levels in the matrix is defined as n;

[0052] Let the total number of points from the beginning of the entire T time domain S to the first high level of the entire T time domain be n1; let the total number of points from the first high level of the entire T time domain to the end E be n2; then in the entire T time domain, the rotor rotates a total of turns;

[0053] Obtain the rotor speed .

[0054] The measurement cycle time is T=0.2s, and high-precision measurement of the rotating speed is achieved, for example, the number of high-level pulses of the rotating speed collected in 0.2s is k=2, that is, k-1=2-1=1 complete revolution of the rotor, and there is a section of incomplete low-level pulse data at the beginning and end, and these data are saved in the matrix as specific digital points, and the total number of points between the last two high levels in the matrix is defined as n at this time;

[0055] The number of points between the first 10V and the second last 10V is n1, and the total number of points from the beginning S of 0.2s to the first high level 10V in the entire 0.2s time domain is n1;

[0056] The number of points between the first 0 and the first 10V in the matrix The total number of points from the last high level 10V to the end E of 0.2s is n2, and the number of points between the first 10V and the first 0V in the matrix In 0.2s, the rotor rotates

[0057]

[0058] The rotating speed of the rotor is obtained

[0059] ;

[0060] If n=200, n1=70, and n2=30, the rotating speed is 180rpm, which provides a new high-precision rotating speed measurement accuracy compared with the existing frequency measurement method and cycle method.

[0061] Further, if the data of multiple rotor systems need to be collected at the same time, multiple remote measurement systems are connected to the same host computer, and all remote measurement systems receive Beidou signals, and a synchronization pulse is output every 1s through the Beidou clock, and the multiple remote measurement systems are time-synchronized after receiving the synchronization pulse, so as to eliminate the running time error of the internal clock, thereby realizing time synchronization between different remote measurement systems and realizing cascade synchronous collection of multiple remote measurement systems. For each output AD clock, the absolute time corresponding to the clock can be known, so that the corresponding Beidou time label can be added to each AD collected data.

[0062] The technical effect of the present application is:

[0063] Propose a kind of telemetry system and method with TOP trigger signal can be cascaded synchronization, the entire telemetry system weight 0.6kg, size diameter D*height H=120mmX60mm, can be conveniently and quickly installed on small and medium-sized electric drive rotor hub, while collecting the rotating load signal such as blade, rotor shaft, TOP signal is collected, and the cascade synchronization of multiple telemetry systems can be collected, facilitate data analysis. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 It is a kind of telemetry system schematic diagram with TOP trigger signal can be cascaded synchronization.

[0065] Figure 2 It is a kind of telemetry system internal structure schematic diagram with TOP trigger signal can be cascaded synchronization.

[0066] Figure 3 It is the schematic diagram of telemetry system adjustment dynamic balance installation position.

[0067] Figure 4 It is the telemetry system load signal acquisition flow chart.

[0068] Figure 5 It is the schematic diagram of multilayer circuit board design.

[0069] Figure 6 It is the telemetry system working signal transmission flow chart.

[0070] Figure 7 It is the internal transmission diagram of rotational speed signal.

[0071] Figure 8 It is the rotational speed principle diagram.

[0072] Figure 9 It is the schematic diagram of two systems not synchronization.

[0073] Figure 10 It is the schematic diagram of two systems synchronization.

[0074] Figure 11 It is the schematic diagram of rotational speed signal and load signal.

[0075] Figure 12 It is the counterweight calculation process schematic diagram.

[0076] Figure 13 It is the rotational speed calculation process schematic diagram. DETAILED DESCRIPTION

[0077] In order to make the person skilled in the art better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the scope of protection of the present application.

[0078] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0079] In addition, the terms "mount", "set", "provided with", "connected", "connected", "sleeved" should be broadly understood. For example, it can be fixedly connected, detachably connected, or integrally constructed; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For the person skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0080] The present application will be further described below in combination with the drawings and embodiments:

[0081] A telemetry system with TOP trigger signal cascading synchronization, as shown in Figure 1 and Figure 2 , contains acquisition module ①, wireless module ②, Beidou signal switching module ③, all placed in the uppermost layer of the system, circuit board ④ placed in the middle layer of the system, using multi-point fastening method, avoiding cantilever beam state; battery assembly ⑤ is placed in the bottom layer of the system, composed of four lithium batteries with a total capacity of 40wh, can be continuously working for 4h under full load, the whole structure forms a compact ladder series structure, which ensures that the system is small in size and light in quality. The whole telemetry system selects a cylindrical structure, which is installed on the upper surface of the hub of the rotor system through an intermediate adapter, and the connection design of the intermediate adapter is reasonable and has reliable anti-loose measures. At the same time, it has anti-vibration and anti-impact design, which meets the requirements of test bench vibration and impact use environment, in addition, it also includes host computer ⑥ (including acquisition program software).

[0082] Telemetry system dynamic balance design

[0083] In order to ensure that the system mass center coincides with the rotation center after installation, the circuit and mounting structure of all rotating parts are designed in a central symmetric arrangement, and the circuit board and components are arranged as symmetrically as possible around the shaft center.

[0084] The circuit arrangement can minimize the mass eccentricity, and the remaining torque that cannot be balanced by the circuit arrangement is balanced by the structural design. The structural design fits the mass eccentricity caused by the circuit arrangement through simulation, and balances the mass eccentricity through structural design, thereby ensuring that the mass center coincides with the rotation center after the design is completed.

[0085] In addition to the design guarantee measures such as symmetric arrangement of components and symmetric balancing of structural design, the rotating part mounting structure also has installation positions for adjusting the mass center of rotation, such as Figure 3 As shown in the figure, there are 24 M3 threaded holes on the circumference of φ114 of the outer ring of the system, and these threaded holes can be balanced by additional installation of mass blocks to eliminate the system mass center deviation caused by factors such as machining errors.

[0086] The installation orientation and mass calculation process of the counterweight block are as follows:

[0087] Step a: define the high pulse trigger point of the rotation speed pulse signal as the zero phase point, record the phase difference of the first-order fundamental frequency signal of the blade load relative to the zero phase point as Φ1, and record the amplitude as A1, then the initial vector point of the load is D1(A1, Φ1), as shown in Figure 12 ;

[0088] Step b: try to install a mass block with a mass of m in any threaded hole, the phase of the mass block with a mass of m relative to the zero phase point is Φ, and the phase angle of the first-order fundamental frequency signal relative to the zero phase point is calculated again, the amplitude is recorded as A2, and D2(A2, Φ2) is recorded;

[0089] Step c: D2-D1=D3(A3, Φ3), D3 is the influence of m counterweight on dynamic balance at phase Φ;

[0090] The amplitude of the influence is A3, the phase is Φ0=Φ-Φ3, the unit mass influence load amplitude A3 / m, and the mass influence phase leads Φ0;

[0091] Step d: according to D3, the initial load D1(A1, Φ1) is balanced, and the counterweight m' = A1*A3 / m needs to be loaded at the phase Φ'=Φ1-Φ0 for dynamic balance.

[0092] Telemetry system load signal acquisition circuit design

[0093] The load signal on the rotor blade is currently collected by pasting a Wheatstone full bridge, and its principle is as follows Figure 4Vi+ and Vi- are the bridge output voltages, and Eg+ and Eg- are the bridge excitation voltages.

[0094] 1) Input mode selection: the channel can realize strain full-bridge and voltage (thermocouple) selection through program-controlled internal relay switching;

[0095] 2) Range switching: the required gain of each range is realized through program-controlled gain switching, and a gain-switchable instrument amplifier is used to ensure each gain range;

[0096] 3) Low-pass filtering: the low-pass filtering cutoff frequency can be set to meet the 2k frequency response requirement of the measured signal and to ensure the signal-to-noise ratio;

[0097] 4) Single-ended to differential conversion: single-ended signals are converted into differential signals for 16-bit ADC acquisition;

[0098] 5) Bridge voltage: multiple bridge voltage ranges are switched through DA switching.

[0099] Anti-interference design of telemetry system acquisition system

[0100] As shown in Figure 5 , a multi-layer circuit board is used, and the circuit board is sequentially composed of a top layer, a power supply ground layer, a power supply layer, a signal layer, a +15V power supply, and a bottom layer. The power supply ground layer, the power supply layer, and the signal layer are reasonably partitioned in the circuit board design, and a large area of copper is applied to the power supply layer. After multiple tests and comparisons, a reasonable design for suppressing interference is found, which has the smallest ground impedance and the smallest circuit noise. The components are reasonably arranged, and the electromagnetic disturbance sources such as digital components and CPU clock generators are shielded and isolated, and are far away from analog components. Measures such as placing connectors and their pins on one side of the printed board and away from high-speed components are taken to effectively suppress common-mode current radiation. Sensitive components are partitioned and far away from electromagnetic disturbance sources in the printed board design.

[0101] All printed boards independently separate the ground lines of power supply voltage, digital circuits, and analog circuits, and find the most appropriate position to short different ground lines through tests. The information acquisition equipment effectively suppresses the electromagnetic interference caused by the transient change of the power supply current in the space and the common impedance coupling interference caused by the inductance of the power supply line by reducing the characteristic impedance of the power supply line and using filtering and decoupling capacitors. Incompatible signal lines are kept away from each other, and multi-layer perpendicular wiring is used to reduce the electric field and magnetic field coupling interference between signal lines. The position of high-speed signal lines is reasonably designed, and shielding measures are taken to avoid interfering with other signal lines.

[0102] Telemetry system working signal transmission process

[0103] As shown in Figure 6The outdoor receiving antenna, the Beidou relay module and the indoor transmitting antenna are mainly used for introducing the outdoor Beidou signal into the indoor to facilitate the remote measurement system to receive the Beidou clock signal through the Beidou signal switching module in the wind tunnel test;

[0104] The rotor system and the acquisition module: the waving, oscillation, torsion and rotating speed signals on the blades in the rotor system are connected through the cable and the acquisition module of the remote measurement system to acquire the load signals;

[0105] The switch and the wireless AP: mainly receiving the data signals transmitted by the remote measurement system through the wireless module, the wireless transmission is through the WiFi mode, adopts the 2.4GHz frequency band, realizes the point-to-point wireless communication between the AP base station and the remote measurement system terminal, the link layer adopts the Ethernet protocol as the core to realize the addressing and checking of the information transmission, realizes the multi-system wireless networking with the communication distance of at least 100 meters, the wireless transmission stability: the number of data packet / data frame loss per hour ≤3. The wireless AP transmits the data to the upper computer through the switch and the network cable for storage, processing and analysis.

[0106] The working steps of the remote measurement system are as follows:

[0107] 1) After the system is completely installed, turn on the power of all instruments, start the control software, read the information of all acquisition instruments, and give the corresponding prompt, that is, how many acquisition instruments are working;

[0108] 2) According to the test requirements, set the parameters of the acquisition instrument, such as the range, filter, input mode, bridge mode, sampling frequency, etc.;

[0109] 3) When the system needs to be synchronized for acquisition, check whether the Beidou communication is normal to ensure the synchronization accuracy;

[0110] 4) If the synchronization acquisition is not needed or the Beidou signal cannot be received due to the weather, the system can not be connected to the Beidou clock, and the internal clock of each system can be directly used for acquisition, but the synchronization accuracy cannot be guaranteed;

[0111] 5) Start sampling to check whether the system can work normally, if not, find the reason;

[0112] 6) All sampling data are transmitted to the related computer in real time through the wireless and wired Ethernet for display processing, analysis and network data distribution;

[0113] 7) After the test is completed, send the stop command, and the acquisition instrument stops sampling immediately after receiving the stop command.

[0114] Design method of rotating speed TOP signal trigger signal acquisition

[0115] For example, Figure 7As shown, the photoelectric sensor is connected with the telemetry acquisition module to rotate together, and the reflective sticker is attached to the non-rotating table body to collect the rotation speed TOP signal. The rotation speed signal collected when triggered is a 10V high level pulse signal, and the voltage value collected when not triggered is 0V low level. The rotation speed signal enters the rotation speed circuit, and the rotation speed sensor is input to the rotation speed channel. After the pulse signal processed by the shaping circuit is input to the rotation speed module in the FPGA (programmable logic device), the rotation speed value is calculated after capturing the rotation speed pulse frequency according to the clock frequency, the key phase is measured, and after combination, the data bus is sent to the control card through the bottom plate.

[0116] Automatic rotation speed measurement method based on load spectrum: according to the high correlation between rotor load signal spectrum and rotor speed, Figure 11 As shown, the current rotor real-time rotation speed can be obtained through spectrum analysis of the load signal, the response speed of the rotation speed obtained by this path can reach milliseconds, and the accuracy can reach 0.01%. In addition, this method can solve the problem that the photoelectric sensor signal is easy to be affected by electromagnetic interference and external light source in outdoor test and flight environment, resulting in inaccurate rotation speed measurement. In the rotor test, the number of rotor blades is S, the flap and eddy signals of the blades mainly include the rotor speed base frequency, the blade passing frequency (S*rotor base frequency), and the blade flap and eddy natural frequency, the rotor shaft load signal frequency mainly includes the rotor speed base frequency, the second order base frequency, the third order base frequency, the blade passing frequency (S*rotor base frequency), and 50HZ public frequency interference,

[0117] When the rotor speed is below 600rpm, the rotor load value is very small, and the peak value of the load spectrum analysis is not obvious, so this rotation speed measurement method has two cases, as shown in Figure 13 The measurement process is as follows:

[0118] 1) When the rotor speed is below 600rpm:

[0119] Step one: given rotation speed signal collection period T=0.1s, the number of high level pulse signals collected in T time is recorded as k;

[0120] Step two: if k<2, it means that there are no two high pulses in T time, i.e. the rotor does not rotate a complete circle, then continue to sample T=T+0.05s period until K≥2,

[0121] Step three: calculate k-1 complete rotor rotation in T time, and there is a segment of incomplete low level pulse data at the head and tail; these data are saved in the form of specific digital points in the matrix, and the total number of points between the last two high levels in the matrix is defined as n at this time.

[0122] The total number of points from the beginning S of the entire T time domain to the first high level of the entire T time domain is denoted as n1; the total number of points from the first high level of the entire T time domain to the end E is denoted as n2; then in the entire T time domain, the rotor rotates a total of turns;

[0123] The rotor speed is obtained ;

[0124] By the end of the cycle speed measurement method, as shown in Figure 8 , the cycle time is T=0.2s, and the high-precision speed measurement is achieved. For example, the number of high-level pulses collected in 0.2s is k=2, that is, k-1=2-1=1 complete rotor rotation, and there is an incomplete low-level pulse data at the beginning and end. These data are saved in the matrix as specific digital points. At this time, the total number of points between the last two high levels in the matrix is defined as n, , which is the number of points between the first 10V and the second last 10V. The total number of points from the beginning S of 0.2s to the first high level 10V of the entire 0.2s time domain is denoted as n1, such as the number of points between the first 0 and the first 10V in the matrix . The total number of points from the last high level 10V of the entire 0.2s time domain to the end E is denoted as n2, such as the number of points between the first 10V and the first 0V in the matrix . Then in 0.2s, the rotor rotates a total of

[0125] ,

[0126] The rotor speed is obtained

[0127] ;

[0128] If n=200, n1=70, and n2=30, the speed is 180rpm. Compared with the existing frequency measurement method and cycle method, it provides a new high-precision speed measurement accuracy for low speed.

[0129] When the rotor speed is greater than 600rpm,

[0130] Step four: Given the signal acquisition cycle T = 0.1s, the number of high-level pulses of the rotating speed collected in T time is recorded as k, K ≥ 2, when the rotating blade flapping, oscillation, rotating shaft tension load is analyzed by FFT, the first five main peak frequencies within 200Hz of the three load signals are analyzed, the first five main peak frequencies of the blade flapping are H = [H1 H2 H3 H4 H5], the first five main peak frequencies of the blade oscillation are B = [B1 B2 B3 B4 B5], and the first five main peak frequencies of the rotor shaft tension are T = [T1 T2 T3 T4 T5], which form a 15-element matrix HBT = [H1 H2 H3 H4 H5 B1 B2 B3 B4 B5 T1 T2 T3 T4 T5]

[0131] Step five: traverse the HBT matrix elements, if there are two frequencies X, Y in it that satisfy Y = S * X, X ∈ HBT, Y ∈ H and Y ∈ B and Y ∈ T, then the rotating speed R = X * 60;

[0132] For example, the number of rotor blade is 5, T = 0.1s, the number of high-level pulses of the rotating speed in 0.1s is k = 3, the rotor load is analyzed, the first five main peak frequencies of the blade flapping are H = [3.5 16.7 2 42.4 78.3 106], the first five main peak frequencies of the blade flapping and oscillation are B = [7.6 21.2 42.4 63.6 106], and the first five main peak frequencies of the rotor shaft tension are T = [21.2 50 100 106 200], then HBT = [3.5 16.7 2 42.4 78.3 106 7.6 21.2 42.4 63.6 106 21.2 50 100 106 200], there are Y = 106Hz = X * 5 = 21.2 * 5 in HBT, and Y = 106Hz belongs to H, B and T elements, so the rotating speed R = X * 60 = 21.2 * 60 = 1272rpm

[0133] Cascade synchronization acquisition of multiple systems: In multi-rotor tests, multiple telemetry systems are often used simultaneously, and multiple telemetry systems can be used simultaneously and the time axis can be synchronized.

[0134] In the case that each system can receive GPS well, each system can receive the Beidou second pulse signal in real time, and the Beidou clock outputs accurate synchronization pulses every 1s, and the two sets of telemetry acquisition systems are synchronized after receiving the synchronization pulses, eliminating the running time error of the internal clock of the acquisition instrument, thereby realizing the time synchronization between different systems and realizing the cascade synchronization acquisition of multiple telemetry systems; the synchronization accuracy is better than 1us. For each output AD clock, the absolute time corresponding to the clock can be known, so that for each AD acquisition data, the corresponding Beidou time label can be added to the data. Figure 9As shown, the telemetry system 1 and system 2 data acquisition time coordinate points at the same time are respectively 11:10:10, 11:10:12, with 2 seconds of time out of synchronization, then simultaneously at a moment receiving the Beidou second pulse signal, time analysis is 11:10:11, at this time the telemetry 1 time is accurate, the telemetry 2 system time is ahead, so the telemetry 2 updates the time data label with the Beidou second pulse signal, because the system sampling rate is fixed, defined as f, the time interval between every two data points is 1 / f, so the telemetry 2 collected data points received Beidou time as the reference, the corresponding time is re-performed, after synchronization as shown. Figure 10

[0135] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A telemetry system with TOP trigger signal cascadeable synchronization, characterized in that: The telemetry system comprises a wireless module, a Beidou signal switching module, an acquisition module, a circuit board, a battery, an upper computer, a sensor assembly, a non-rotating platform body and a device shell; The rotor system is arranged on the non-rotating platform body, the device shell is a cylindrical shell with an open top, and the device shell is arranged above the hub of the rotor system through an intermediate adapter; the circuit board is arranged at the opening of the device shell, and the battery is connected below the circuit board; the wireless module, the Beidou signal switching module and the acquisition module are connected above the circuit board; The sensor assembly is arranged on the rotor system and connected to the acquisition module through a cable; the Beidou signal switching module is used for receiving a Beidou signal; and the wireless module is used for communicating with the upper computer; The sensor assembly comprises a load measuring assembly and a rotating speed measuring assembly; The acquisition module acquires the waving load of the rotating blade, the oscillating load of the rotating blade, the pulling load of the rotating shaft and the rotating speed pulse signal; The upper computer sets the rotating speed pulse signal acquisition period T = 0.1 s, and the number of high-level pulses of the rotating speed acquired in T time is recorded as k; If k < 2, T is assigned as T + 0.05 s, and the rotating speed is measured by the end period method until k ≥ 2; If k ≥ 2, the waving load of the rotating blade, the oscillating load of the rotating blade and the pulling load of the rotating shaft are subjected to FFT analysis to obtain the first five main peak frequencies of the three load signals within 200 Hz, the first five main peak frequencies of the waving load of the blade are H = [H1H2H3H4H5], the first five main peak frequencies of the oscillating load of the blade are B = [B1B2B3B4B5], and the first five main peak frequencies of the pulling load of the rotating shaft are T = [T1T2T3T4T5], and a 15-element matrix HBT = [H1H2H3H4H5B1B2B3B4B5T1T2T3T4T5] is formed; The elements of the HBT matrix are traversed, and if two frequencies X and Y exist in the matrix and satisfy Y = S * X, X ∈ HBT, Y ∈ H and Y ∈ B and Y ∈ T, then the rotating speed R = X * 60; The mass center of the whole formed by the intermediate adapter, the device shell and all the devices carried by the device shell coincides with the rotating center of the rotor system; The circuit board and the devices carried by the circuit board are symmetrically arranged around the rotating center of the rotor system; The wireless module, the Beidou signal switching module and the acquisition module are designed in a central symmetric arrangement manner; A trimming structure is designed on the circuit board to compensate for the mass eccentricity of the circuit board; the installation position and mass of the trimming structure are obtained through simulation; Threaded holes are uniformly arranged on the circumferential edge of the circuit board, and mass blocks are installed on the threaded holes to eliminate the mass eccentricity caused by the machining and installation errors; the installation direction and mass of the counterweight block are calculated as follows: Step a: the high pulse trigger point of the rotating speed pulse signal is defined as a zero phase point, the phase difference of the first-order fundamental frequency signal of the blade load relative to the zero phase point is recorded as Φ1, the amplitude is recorded as A1, and the initial vector point of the load is D1(A1, Φ1); Step b: a mass block with a mass of m is installed at any threaded hole, the phase of the mass block with a mass of m relative to the zero phase point is Φ, the phase angle Φ2 of the first-order fundamental frequency signal relative to the zero phase point is calculated again, the amplitude is recorded as A2, and it is recorded as D2(A2, Φ2); Step c: D2-D1=D3(A3,Φ3), D3 is the influence of m counterweight on the dynamic balance of Φ phase, the amplitude of influence is A3, the phase is Φ0=Φ-Φ3, the unit mass influence load amplitude is A3 / m, the mass influence phase leads Φ0; Step d: According to D3, the initial load D1(A1, Φ1) is trimmed, and the trimmed dynamic balance needs to load the counterweight m'=A1*A3 / m at the phase Φ'=Φ1-Φ0. The load measuring assembly is a Wheatstone full bridge attached to the blade.

2. The telemetry system of claim 1, wherein: The rotating speed measuring assembly comprises a photoelectric sensor and a reflective sticker.

3. The telemetry system of claim 1, wherein: The photoelectric sensor is installed on the sidewall of the intermediate adapter. The reflective sticker is attached to the non-rotating platform and located directly below the photoelectric sensor. The circuit board is a multilayer circuit board, and from top to bottom, there are top layer, power supply ground layer, power supply layer, signal layer, +15V power supply layer and bottom layer, and the power supply layer is large-area copper clad.

4. The telemetry system of claim 1, wherein: The power supply voltage, digital circuit and analog circuit ground in each layer of the circuit board are independently separated. The method comprises the following steps:

5. A telemetry method with TOP trigger signal cascade synchronization, the method is implemented based on the telemetry system in any one of claims 1-4, characterized in that: 1) Install the telemetry system and turn on the power supply; 2) Set parameters according to test requirements, including: range, filter, input mode, bridge mode and sampling frequency; 3) When multiple telemetry systems need to be synchronously collected, check whether the Beidou signal reception is normal; 4) If synchronous collection is not needed or the Beidou signal cannot be received, directly use the internal clock of the telemetry system to collect signals; collect the rotating blade flap load, the rotating blade edgewise load and the rotating shaft tension load; collect the rotating speed pulse signal; and calculate the rotating speed as follows: Step one: set the rotating speed pulse signal collection period T=0.1s, and the number of rotating speed high level pulses collected in T time is recorded as k; Step two: if k<2, jump to step three; if k≥2, jump to step six; Step three: T=T+0.05s; Step four: judge whether k is greater than or equal to 2, if yes, jump to step five, otherwise return to step three; Step five: collect k-1 complete rotor rotation circles in T time, and there are one incomplete low level pulse data at the head and tail; these data are saved in the form of specific digital points in the matrix, and the total number of points between the last two high level pulses in the matrix is defined as n; Step six: perform FFT analysis on the rotating blade flap load, the rotating blade edgewise load and the rotating shaft tension load, obtain the first five main peak frequencies of the three load signals within 200Hz, the first five main peak frequencies of the blade flap load are H=[H1H2H3H4H5], the first five main peak frequencies of the blade edgewise load are B=[B1B2B3B4B5], and the first five main peak frequencies of the rotor shaft tension load are T=[T1T2T3T4T5], and a 15-element matrix HBT=[H1H2H3H4H5B1B2B3B4B5T1T2T3T4T5] is formed; The total number of points from the beginning S of the entire T time domain to the first high level of the entire T time domain is denoted as n1; the total number of points from the first high level of the entire T time domain to the end E is denoted as n2; then in the entire T time domain, the rotor rotates a total of turns; Obtaining rotor speed Step seven: traverse the elements of the HBT matrix, if there are two frequencies X and Y in the matrix that satisfy Y=S*X, X∈HBT, Y∈H and Y∈T, then the rotating speed R=X*60. ​ 5) All signal sampling data is transmitted to the host computer in real time for display processing, analysis and network data distribution; 6) After the test is completed, send a stop command to stop sampling.

6. The method according to claim 5, characterized in that: The speed pulse signal collected when the photoelectric sensor is triggered is a 10V high-level pulse signal, and the speed pulse signal collected when it is not triggered is a 0V low-level pulse signal.

7. The method of claim 5, wherein: If it is necessary to collect data from multiple rotor systems at the same time, multiple telemetry systems are connected to the same host computer, and all telemetry systems receive Beidou signals. A synchronization pulse is output every 1 second through the Beidou clock. After receiving the synchronization pulse, multiple telemetry systems are synchronized to eliminate the timing error of the internal clock, thereby achieving time synchronization between different telemetry systems and realizing cascaded synchronous collection of multiple telemetry systems.

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