阅读说明：本技术 空间充气可展开支撑结构的动刚度在轨监测装置及方法 (Dynamic stiffness on-orbit monitoring device and method for space inflation expandable support structure ) 是由 徐超 李鹏飞 颜津玮 于 2021-07-15 设计创作，主要内容包括：本发明公开了一种空间充气可展开支撑结构的动刚度在轨监测装置及方法,包括顶盖、电路板和盒体；电路板安装在盒体内部；顶盖安装在盒体顶面,将盒体封闭；电路板包括信号发生模块、信号采集模块、微处理器模块、串口通信模块、数据存储模块和电源管理模块；微处理器模块控制信号发送模块产生指定频率的正弦扫频信号,并使能信号采集模块进行数据采集；信号采集模块采集完成后,微处理器模块对采集的激励信号和响应信号分别进行短时傅里叶变换,并通过求取激励信号和响应信号的比值得到充气可展开支撑结构的动刚度数据,再将动刚度数据传输到SD卡中进行存储。本发明装置具有小型化、模块化、低功耗的特点,节省了航天器的载荷空间,节约了能源。(The invention discloses a dynamic stiffness on-track monitoring device and method of a space inflation expandable support structure, which comprises a top cover, a circuit board and a box body, wherein the top cover is provided with a plurality of air holes; the circuit board is arranged inside the box body; the top cover is arranged on the top surface of the box body to seal the box body; the circuit board comprises a signal generating module, a signal collecting module, a microprocessor module, a serial port communication module, a data storage module and a power management module; the microprocessor module controls the signal sending module to generate a sine frequency sweeping signal with specified frequency and enables the signal acquisition module to acquire data; after the signal acquisition module finishes acquisition, the microprocessor module respectively carries out short-time Fourier transform on the acquired excitation signal and response signal, obtains dynamic stiffness data of the inflatable expandable support structure by calculating the ratio of the excitation signal to the response signal, and then transmits the dynamic stiffness data to the SD card for storage. The device has the characteristics of miniaturization, modularization and low power consumption, saves the loading space of the spacecraft and saves energy.)

1. The dynamic stiffness on-orbit monitoring device of the space inflation expandable support structure is characterized by comprising a top cover, a circuit board, a micro rectangular connector and a box body; the circuit board is arranged inside the box body; the top cover is arranged on the top surface of the box body to seal the box body; the bottom surface of the box body is provided with a plurality of bolt holes for installing the dynamic stiffness on-orbit monitoring device on a spacecraft wall plate through bolts; the micro rectangular connector is arranged on the side wall inside the box body, the inner pin end of the micro rectangular connector is electrically connected with the circuit board, and the interface end of the micro rectangular connector can be electrically connected with the inflatable deployable supporting structure;

the circuit board comprises a signal generation module, a signal acquisition module, a microprocessor module, a serial port communication module, a data storage module and a power management module;

the signal generation module generates a sine sweep frequency signal, and outputs an excitation signal to the inflatable expandable support structure through the excitation output channel after amplification, so that the inflatable expandable support structure generates vibration; the signal acquisition module synchronously acquires an excitation signal output by the signal generation module and a response signal generated by the vibration of the inflatable expandable support structure; the microprocessor module realizes the control of each module of the dynamic stiffness on-orbit monitoring device and the calculation of dynamic stiffness data; the serial port communication module realizes serial port to USB conversion, and realizes instruction sending and data transmission between the satellite borne computer and the dynamic stiffness on-orbit monitoring device by connecting a USB wire; the data storage module is used for storing dynamic stiffness data; and the power supply management module is used for supplying power to other modules of the dynamic stiffness on-orbit monitoring device.

2. The device for monitoring the dynamic stiffness of the spatially-inflated deployable support structure in the on-orbit according to claim 1, wherein the signal generation module comprises a signal generation circuit, a channel selection circuit and a programmable amplification circuit; the signal generating circuit adopts an AD9834 DDS chip and can simultaneously output 2 paths of sine frequency sweeping signals with the frequency of 100 KHz; the channel selection circuit consists of two BL1551 single-pole double-throw analog switch chips, and the microprocessor module realizes the selection of an excitation output channel by enabling an EN pin of the BL1551 chip; the program-controlled amplifying circuit amplifies the peak value of the excitation signal to 24V at maximum.

3. The device for monitoring the dynamic stiffness of the spatial inflatable deployable support structure in orbit as claimed in claim 1, wherein the signal acquisition module realizes the synchronous acquisition of 6 response signals and 2 excitation signals at a sampling rate of 200KHz, and the acquired signals are read by the microprocessor module through SPI serial communication.

4. The device for monitoring the dynamic stiffness of the spatial inflatable deployable supporting structure in the orbit as claimed in claim 1, wherein the microprocessor module adopts an STM32F103ZFT6 chip as a processor chip.

5. The dynamic stiffness in-orbit monitoring device of the space inflation expandable supporting structure as claimed in claim 1, wherein the serial port communication module adopts a CH340G chip to realize serial port to USB conversion, and realizes command sending and data transmission between the on-board computer and the dynamic stiffness in-orbit monitoring device by connecting a USB wire, and the data transmission rate is up to 2 Mbps.

6. The device for monitoring the dynamic stiffness of the spatially inflatable and deployable support structure in orbit of claim 1, wherein the data storage module uses an SD card as a storage device and supports SDIO protocol for data communication.

7. The device of claim 1, wherein the power management module is responsible for supplying power to other modules of the device, and the power management module receives 5V from the USB input, and after conversion between the AMS117-3.3 power chip and the MAX743 power chip, obtains +3.3V and ± 12V, and supplies +5V, +3.3V and ± 12V.

8. The on-track dynamic stiffness monitoring device for a spatially inflatable deployable support structure of claim 1, wherein the on-track dynamic stiffness monitoring device is capable of simultaneously on-track monitoring the dynamic stiffness of 2 inflatable deployable support structures, each path comprising an excitation and sensor system comprising 1 piezo-electric sheet driver and 2 piezo-electric sheet sensors disposed on an inflatable membrane of the inflatable deployable support structure, wherein the piezo-electric sheet drivers apply a sinusoidal sweep frequency signal to the on-track dynamic stiffness monitoring device to excite the inflatable deployable support structure, and the piezo-electric sheet sensors are configured to sense vibration of the inflatable deployable support structure and generate charge signals.

9. An on-orbit monitoring method for dynamic stiffness of a space inflation expandable support structure is characterized by comprising the following steps of:

step 1: after the inflatable expandable support structure is expanded, the satellite-borne computer sends a starting measurement instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the signal generating module, the signal collecting module and the data storage module at intervals of a designated period, starts 2 excitation channels, and starts a timer TIM3 and a timer TIM4 in the microprocessor module;

and step 3: the microprocessor module sends a frequency control word corresponding to the designated frequency to the signal sending module in an interrupt function generated by the timer TIM3 in an SPI communication mode, so that the signal sending module generates a sine frequency sweeping signal of the designated frequency according to the frequency control word and enables the signal acquisition module to acquire data in the interrupt function generated by the timer TIM 4;

and 4, step 4: after the signal acquisition module finishes acquisition, the microprocessor module respectively performs short-time Fourier transform on the acquired excitation signal and response signal, obtains dynamic stiffness data of the inflatable expandable support structure by solving the ratio of the excitation signal to the response signal, and then transmits the dynamic stiffness data to the SD card for storage;

and 5: after the data storage is finished, the microprocessor module enables the signal generation module, the signal acquisition module and the data storage module to enter a sleep mode to wait for the start of the next measurement.

10. A method for transmitting on-orbit monitoring data of dynamic stiffness of a space inflation expandable support structure is characterized by comprising the following steps:

step 1: the on-board computer sends a data transmission instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the data storage module and the serial port communication module;

and step 3: the microprocessor module reads data in the SD card and sends the data to the spaceborne computer through the USB;

and 4, step 4: after the data transmission task is finished, enabling the data storage module and the serial port communication module to enter a sleep mode by the microprocessor module;

and 5: and after receiving the dynamic stiffness data, the satellite-borne computer sends the data to the ground.

Technical Field

The invention belongs to the technical field of spaceflight, and particularly relates to an on-orbit dynamic stiffness monitoring device and method.

Background

The space inflation expandable structure has the remarkable advantages of small folding volume, light weight, easiness in expansion, easiness in storage, low cost and the like, and has wide application prospects in aerospace engineering. Space-inflating, expandable structures are generally composed of a membrane and a support structure, wherein the support structure essentially comprises an inflatable, expandable support rod and a support ring. In a large-space inflatable and expandable antenna system, an inflatable and expandable support rod and a support ring are used for expanding and maintaining a reflecting surface in the antenna system; in a solar sail, inflatable deployable support rods are used to deploy and support the sail surface. The inflatable expandable support structure mainly realizes the expansion of a space inflatable structure in an inflation mode, provides power for the expansion of the structure, and plays a role in keeping the appearance of the structure by keeping certain rigidity formed by inflation pressure. After the inflatable expandable support structure is expanded, the on-orbit dynamic stiffness characteristic of the inflatable expandable support structure has important influence on the vibration characteristic of the whole inflatable structure, the attitude control of a spacecraft platform and the like, and the on-orbit in-situ measurement and real-time monitoring of the dynamic stiffness characteristic of the inflatable expandable support structure have very important engineering value.

At present, some research at home and abroad focuses on testing the dynamic stiffness of a space inflatable deployable supporting structure on the ground. The Slade is excited by an electromagnetic vibrator, and the dynamic stiffness characteristic of the inflatable structure is obtained by collecting signals by a laser oscillator (Slade K.dynamic characteristics of thin-film inflectable structures [ M ]. Durham: Duke University, 2000.). Thomas adopts an electromagnetic vibrator and a piezoelectric sheet sensor to excite an inflation rod, and respectively adopts an acceleration sensor and a laser vibrometer to acquire vibration signals to obtain the dynamic stiffness characteristic of an inflation structure (Single T. Experimental vibration analysis of inflatable beams for an AFIT space program experiment R. Ohio: Air University, 2002.). The dynamic test of the inflatable ring structure is carried out on the ground by a force hammer impact method in the rest of innovation and the like, a single built-in circuit piezoelectric sheet sensor is selected for measuring response, a commercial dynamic data analyzer is used for acquiring data, and modal parameters are extracted to obtain a frequency response function of the inside and outside vibration of the film inflatable ring (rest of innovation, Weijian, Tanhuifeng, dynamic characteristic test research of the film inflatable ring [ J ] vibration and impact, 2013,32(7): 11-11.). However, it should be noted that these studies are conducted on the ground, and dynamic stiffness tests are conducted on the inflatable deployable support structure by using commercial structure dynamics testing equipment with large volume and power consumption. Due to the limitation of volume and power consumption and the complexity of a system, the device and the method cannot be used for testing the space on-orbit state, and simultaneously have no continuous real-time dynamic stiffness monitoring capability.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a dynamic stiffness on-track monitoring device and method of a space inflation expandable support structure, which comprises a top cover, a circuit board and a box body, wherein the top cover is provided with a first end and a second end; the circuit board is arranged inside the box body; the top cover is arranged on the top surface of the box body to seal the box body; the circuit board comprises a signal generating module, a signal collecting module, a microprocessor module, a serial port communication module, a data storage module and a power management module; the microprocessor module controls the signal sending module to generate a sine frequency sweeping signal with specified frequency and enables the signal acquisition module to acquire data; after the signal acquisition module finishes acquisition, the microprocessor module respectively carries out short-time Fourier transform on the acquired excitation signal and response signal, obtains dynamic stiffness data of the inflatable expandable support structure by calculating the ratio of the excitation signal to the response signal, and then transmits the dynamic stiffness data to the SD card for storage. The device has the characteristics of miniaturization, modularization and low power consumption, saves the loading space of the spacecraft and saves energy.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a dynamic stiffness on-orbit monitoring device of a space inflation expandable support structure comprises a top cover, a circuit board, a micro rectangular connector and a box body; the circuit board is arranged inside the box body; the top cover is arranged on the top surface of the box body to seal the box body; the bottom surface of the box body is provided with a plurality of bolt holes for installing the dynamic stiffness on-orbit monitoring device on a spacecraft wall plate through bolts; the micro rectangular connector is arranged on the side wall inside the box body, the inner pin end of the micro rectangular connector is electrically connected with the circuit board, and the interface end of the micro rectangular connector can be electrically connected with the inflatable deployable supporting structure;

the circuit board comprises a signal generation module, a signal acquisition module, a microprocessor module, a serial port communication module, a data storage module and a power management module;

the signal generation module generates a sine sweep frequency signal, and outputs an excitation signal to the inflatable expandable support structure through the excitation output channel after amplification, so that the inflatable expandable support structure generates vibration; the signal acquisition module synchronously acquires an excitation signal output by the signal generation module and a response signal generated by the vibration of the inflatable expandable support structure; the microprocessor module realizes the control of each module of the dynamic stiffness on-orbit monitoring device and the calculation of dynamic stiffness data; the serial port communication module realizes serial port to USB conversion, and realizes instruction sending and data transmission between the satellite borne computer and the dynamic stiffness on-orbit monitoring device by connecting a USB wire; the data storage module is used for storing dynamic stiffness data; and the power supply management module is used for supplying power to other modules of the dynamic stiffness on-orbit monitoring device.

Furthermore, the signal generation module comprises a signal generation circuit, a channel selection circuit and a program control amplification circuit; the signal generating circuit adopts an AD9834 DDS chip and can simultaneously output 2 paths of sine frequency sweeping signals with the frequency of 100 KHz; the channel selection circuit consists of two BL1551 single-pole double-throw analog switch chips, and the microprocessor module realizes the selection of an excitation output channel by enabling an EN pin of the BL1551 chip; the program-controlled amplifying circuit amplifies the peak value of the excitation signal to 24V at maximum.

Further, the signal acquisition module realizes synchronous acquisition of 6 paths of response signals and 2 paths of excitation signals at a sampling rate of 200KHz, and the acquired signals are read by the microprocessor module through SPI serial communication.

Further, the microprocessor module adopts an STM32F103ZFT6 chip as a processor chip.

Further, the serial port communication module adopts a CH340G chip to realize serial port to USB conversion, and realizes instruction sending and data transmission between the satellite-borne computer and the dynamic stiffness on-orbit monitoring device by connecting a USB wire, wherein the highest data transmission rate is 2 Mbps.

Furthermore, the data storage module adopts an SD card as storage equipment and supports SDIO protocol for data communication.

Furthermore, the power management module is responsible for supplying power to other modules of the dynamic stiffness on-track monitoring device, 5V voltage is input into the power management module through a USB, and after the 5V voltage is converted by the AMS117-3.3 power chip and the MAX743 power chip, the +3.3V voltage and the +/-12V voltage are obtained, and the supplied voltages are +5V, +3.3V and +/-12V.

Further, the dynamic stiffness on-track monitoring device can simultaneously monitor the dynamic stiffness of 2 paths of inflatable deployable support structures on-track, each path is composed of an excitation and sensor system consisting of 1 piezoelectric sheet driver and 2 piezoelectric sheet sensors which are arranged on an inflatable film of the inflatable deployable support structure, wherein the piezoelectric sheet drivers apply sinusoidal sweep frequency signals to the passive stiffness on-track monitoring device to excite the inflatable deployable support structures, and the piezoelectric sheet sensors are used for sensing the vibration of the inflatable deployable support structures and generating charge signals.

An on-orbit monitoring method for the dynamic stiffness of a space inflation deployable supporting structure comprises the following steps:

step 1: after the inflatable expandable support structure is expanded, the satellite-borne computer sends a starting measurement instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the signal generating module, the signal collecting module and the data storage module at intervals of a designated period, starts 2 excitation channels, and starts a timer TIM3 and a timer TIM4 in the microprocessor module;

and step 3: the microprocessor module sends a frequency control word corresponding to the designated frequency to the signal sending module in an interrupt function generated by the timer TIM3 in an SPI communication mode, so that the signal sending module generates a sine frequency sweeping signal of the designated frequency according to the frequency control word and enables the signal acquisition module to acquire data in the interrupt function generated by the timer TIM 4;

and 4, step 4: after the signal acquisition module finishes acquisition, the microprocessor module respectively performs short-time Fourier transform on the acquired excitation signal and response signal, obtains dynamic stiffness data of the inflatable expandable support structure by solving the ratio of the excitation signal to the response signal, and then transmits the dynamic stiffness data to the SD card for storage;

and 5: after the data storage is finished, the microprocessor module enables the signal generation module, the signal acquisition module and the data storage module to enter a sleep mode to wait for the start of the next measurement.

A method for transmitting on-orbit monitoring data of dynamic stiffness of a space inflation expandable support structure comprises the following steps:

step 1: the on-board computer sends a data transmission instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the data storage module and the serial port communication module;

and step 3: the microprocessor module reads data in the SD card and sends the data to the spaceborne computer through the USB;

and 4, step 4: after the data transmission task is finished, enabling the data storage module and the serial port communication module to enter a sleep mode by the microprocessor module;

and 5: and after receiving the dynamic stiffness data, the satellite-borne computer sends the data to the ground.

The invention has the following beneficial effects:

1. the device only occupies a small spacecraft loading space. The circuit board in the device adopts the modularized design, the layout among the modules is orderly and compact, and the load space of the spacecraft is greatly saved.

2. The power consumption of the device is only 1.25W when the device executes the measurement task on the track, and the energy is greatly saved.

3. The device has a data storage function, does not need to occupy the storage space of the satellite borne computer, and only needs to transmit the dynamic stiffness data to the satellite borne computer according to the data transmission instruction sent by the satellite borne computer.

4. The device has the characteristics of miniaturization, modularization and low power consumption, is easy to integrate with a spacecraft, and can be used for in-orbit in-situ measurement and real-time monitoring of the dynamic stiffness characteristic of the inflatable deployable supporting structure.

Drawings

FIG. 1 is a general block diagram of the apparatus of the present invention.

FIG. 2 is a schematic diagram of the apparatus of the present invention.

FIG. 3 is a circuit board diagram of the device of the present invention.

FIG. 4 is a J30J-15ZK micro rectangular connector of the device of the present invention.

Fig. 5 is a schematic diagram of the arrangement of piezoelectric patches in a spatially inflated deployable strut structure of the device of the present invention.

FIG. 6 is a dynamic stiffness characteristic of a spatially inflatable deployable strut structure in the apparatus of the invention.

The device comprises a 1-top cover, a 2-circuit board, a 3-box body, a 4-M3 bolt hole, a 5-SMA interface, a 6-J30J-15ZK micro rectangular connector interface, a 7-USB interface, an 8-4 x 1 reverse bend pin header interface, a 9-SD card socket, a 10-USB female socket, an 11-SMA connector, a 12-4 x 1 reverse bend pin header, a 13-6 x 2 straight pin header, a 14-J30J-15ZK micro rectangular connector inner pin, a 15-J30J-15ZK micro rectangular connector, a 16-piezoelectric driver, a 17-piezoelectric sensor, an 18-top socket, a 19-base and a 20-polyimide film.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The invention provides a miniaturized, integrated and low-power-consumption dynamic stiffness on-orbit monitoring device applied to a space inflatable deployable supporting structure, and aims to realize on-orbit in-situ measurement and real-time monitoring of the dynamic stiffness characteristic of the space inflatable deployable supporting structure in the service process and provide guarantee for the safe operation of a spacecraft.

A dynamic stiffness on-orbit monitoring device of a space inflation expandable support structure comprises a top cover, a circuit board, a micro rectangular connector and a box body; the circuit board is arranged inside the box body; the top cover is arranged on the top surface of the box body to seal the box body; the bottom surface of the box body is provided with a plurality of bolt holes for installing the dynamic stiffness on-orbit monitoring device on a spacecraft wall plate through bolts; the micro rectangular connector is arranged on the side wall inside the box body, the inner pin end of the micro rectangular connector is electrically connected with the circuit board, and the interface end of the micro rectangular connector can be electrically connected with the inflatable deployable supporting structure;

the circuit board comprises a signal generation module, a signal acquisition module, a microprocessor module, a serial port communication module, a data storage module and a power management module;

the signal generation module generates a sine sweep frequency signal, and outputs an excitation signal to the inflatable expandable support structure through the excitation output channel after amplification, so that the inflatable expandable support structure generates vibration; the signal acquisition module synchronously acquires an excitation signal output by the signal generation module and a response signal generated by the vibration of the inflatable expandable support structure; the microprocessor module realizes the control of each module of the dynamic stiffness on-orbit monitoring device and the calculation of dynamic stiffness data; the serial port communication module realizes serial port to USB conversion, and realizes instruction sending and data transmission between the satellite borne computer and the dynamic stiffness on-orbit monitoring device by connecting a USB wire; the data storage module is used for storing dynamic stiffness data; and the power supply management module is used for supplying power to other modules of the dynamic stiffness on-orbit monitoring device.

Furthermore, the signal generation module comprises a signal generation circuit, a channel selection circuit and a program control amplification circuit; the signal generating circuit adopts an AD9834 DDS chip and can simultaneously output 2 paths of sine frequency sweeping signals with the frequency of 100 KHz; the channel selection circuit consists of two BL1551 single-pole double-throw analog switch chips, and the microprocessor module realizes the selection of an excitation output channel by enabling an EN pin of the BL1551 chip; the program-controlled amplifying circuit amplifies the peak value of the excitation signal to 24V at maximum.

Further, the signal acquisition module realizes synchronous acquisition of 6 paths of response signals and 2 paths of excitation signals at a sampling rate of 200KHz, and the acquired signals are read by the microprocessor module through SPI serial communication.

Further, the microprocessor module adopts an STM32F103ZFT6 chip as a processor chip.

Further, the serial port communication module adopts a CH340G chip to realize serial port to USB conversion, and realizes instruction sending and data transmission between the satellite-borne computer and the dynamic stiffness on-orbit monitoring device by connecting a USB wire, wherein the highest data transmission rate is 2 Mbps.

Furthermore, the data storage module adopts an SD card as storage equipment and supports SDIO protocol for data communication.

Furthermore, the power management module is responsible for supplying power to other modules of the dynamic stiffness on-track monitoring device, 5V voltage is input into the power management module through a USB, and after the 5V voltage is converted by the AMS117-3.3 power chip and the MAX743 power chip, the +3.3V voltage and the +/-12V voltage are obtained, and the supplied voltages are +5V, +3.3V and +/-12V.

Further, the dynamic stiffness on-track monitoring device can simultaneously monitor the dynamic stiffness of 2 paths of inflatable deployable support structures on-track, each path is composed of an excitation and sensor system consisting of 1 piezoelectric sheet driver and 2 piezoelectric sheet sensors which are arranged on an inflatable film of the inflatable deployable support structure, wherein the piezoelectric sheet drivers apply sinusoidal sweep frequency signals to the passive stiffness on-track monitoring device to excite the inflatable deployable support structures, and the piezoelectric sheet sensors are used for sensing the vibration of the inflatable deployable support structures and generating charge signals.

An on-orbit monitoring method for the dynamic stiffness of a space inflation deployable supporting structure comprises the following steps:

step 1: after the inflatable expandable support structure is expanded, the satellite-borne computer sends a starting measurement instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the signal generating module, the signal collecting module and the data storage module at intervals of a designated period, starts 2 excitation channels, and starts a timer TIM3 and a timer TIM4 in the microprocessor module;

and step 3: the microprocessor module sends a frequency control word corresponding to the designated frequency to the signal sending module in an interrupt function generated by the timer TIM3 in an SPI communication mode, so that the signal sending module generates a sine frequency sweeping signal of the designated frequency according to the frequency control word and enables the signal acquisition module to acquire data in the interrupt function generated by the timer TIM 4;

and 4, step 4: after the signal acquisition module finishes acquisition, the microprocessor module respectively performs short-time Fourier transform on the acquired excitation signal and response signal, obtains dynamic stiffness data of the inflatable expandable support structure by solving the ratio of the excitation signal to the response signal, and then transmits the dynamic stiffness data to the SD card for storage;

and 5: after the data storage is finished, the microprocessor module enables the signal generation module, the signal acquisition module and the data storage module to enter a sleep mode to wait for the start of the next measurement.

Step 6, transmitting dynamic stiffness data by the dynamic stiffness on-orbit monitoring device

A method for transmitting on-orbit monitoring data of dynamic stiffness of a space inflation expandable support structure comprises the following steps:

step 1: the on-board computer sends a data transmission instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the data storage module and the serial port communication module;

and step 3: the microprocessor module reads data in the SD card and sends the data to the spaceborne computer through the USB;

and 4, step 4: after the data transmission task is finished, enabling the data storage module and the serial port communication module to enter a sleep mode by the microprocessor module;

and 5: and after receiving the dynamic stiffness data, the satellite-borne computer sends the data to the ground.

The specific embodiment is as follows:

as shown in fig. 1, the dynamic stiffness on-track monitoring device comprises a top cover, a circuit board and a box body. Wherein, the circuit board and the box body and the top cover and the box body are tightly connected together by 4M 3 bolts respectively. After the connection is finished, the size of the dynamic stiffness in-orbit monitoring device is 150mm multiplied by 30mm, the mass is 350g, and the occupied space of the spacecraft is small. The bottom surface of the dynamic stiffness on-orbit monitoring device is a plane with M3 bolt holes at four corners, so that the dynamic stiffness on-orbit monitoring device has good operability, can be tightly connected to a spacecraft wall plate only by utilizing 4M 3 bolts, and is very easy for spacecraft integration.

The circuit board in the dynamic stiffness on-orbit monitoring device adopts a modular design, the layout among modules is orderly and compact, the size of the circuit board is greatly reduced, the size of the dynamic stiffness on-orbit monitoring device is optimized, and the occupied space for loading the spacecraft is reduced. The circuit board functionally integrates a signal generation module, a signal acquisition module, a microprocessor module, a serial communication module, a data storage module and a power management module, and the principle of each module is realized as shown in fig. 2.

The signal generation module comprises a signal generation circuit, a channel selection circuit and a program control amplification circuit. The signal generating circuit adopts an AD9834 DDS chip, an external clock of the chip adopts a 1MHz active crystal oscillator, the output frequency resolution reaches 0.004Hz, and 2 paths of sine sweep frequency signals with the frequency up to 100KHz can be simultaneously output; the channel selection circuit consists of two BL1551 single-pole double-throw analog switch chips, and the microprocessor module realizes the selection of an excitation output channel by enabling an EN pin of the BL1551 chip; the program-controlled amplifying circuit is respectively provided with 1 AD623 operational amplifier chip, 1 MCP1100 digital potentiometer chip and 1 3296W resistor with the resistance value of 100K omega for 2 paths of excitation signals, the AD623 operational amplifier chip adopts +/-12V power supply and can amplify the peak value of the excitation signals to 24V at maximum, the MCP1110 chip is controlled by the processor chip through analog IIC communication and used for determining amplification gain, and the 3296W resistor is used for eliminating direct current bias existing in the output excitation signals through manual adjustment of the resistance value of the resistor.

The signal acquisition module adopts an AD7606 chip to realize an analog-digital conversion function, the module can realize synchronous acquisition of 6 paths of response signals and 2 paths of excitation signals at a sampling rate as high as 200KHz, and the acquired signals can be read by the microprocessor module through SPI serial communication.

The microprocessor module adopts an STM32F103ZFT6 chip with low power consumption as a processor chip, and the peripheral circuit comprises a high/low frequency crystal oscillator circuit, a reset circuit and a program downloading circuit. Wherein the processor chip has up to 768KB of flash memory and 96KB of SRAM; the high/low frequency crystal oscillator circuit respectively adopts 8MHz and 32.768KHz passive crystal oscillators to provide two external clocks for the processor chip; the reset circuit can reset the dynamic stiffness on-track monitoring device to start executing a program; the program downloading circuit adopts an SWD downloading mode, only four lines are needed, and 2 interface resources of the processor chip are occupied.

The serial port communication module adopts a CH340G chip to realize serial port to USB conversion, and realizes instruction sending and data transmission between the satellite borne computer and the dynamic stiffness on-orbit monitoring device by connecting a USB wire, and the data transmission rate can reach 2Mbps at most.

The data storage module adopts an SD card as storage equipment of the data storage module, does not need to occupy the storage space of an on-board computer, supports an SDIO protocol to carry out data communication, and can freely select the capacity according to the on-orbit running time of the spacecraft.

The power management module is responsible for supplying power for other modules of the dynamic stiffness on-track monitoring device, 5V voltage is input into the module through a USB, and the voltage of the module is converted by an AMS117-3.3 power chip and a MAX743 power chip to obtain +3.3V and +/-12V, wherein the voltage provided by the module is +5V, +3.3V and +/-12V.

There are 1 SD cassette, 1 USB female seat, 2 SMA connectors, 14 x 1 recurved pin header, 16 x 2 straight-insert pin header on the circuit board of dynamic stiffness on-track monitoring device, as shown in fig. 3. The USB female seat, the SMA connector and the 4 x 1 reverse-bent pin are respectively and directly connected with a USB interface, an SMA interface and a 4 x 1 reverse-bent pin interface on the surface of the box body, and the 6 x 2 direct-inserted pin is firstly connected with an inner pin of the J30J-15ZK micro rectangular connector through a lead, and then the J30J-15ZK micro rectangular connector is connected with an interface of the J30J-15ZK micro rectangular connector on the surface of the box body. The structure of the J30J-15ZK micro rectangular connector is shown in FIG. 4.

The assembling process of the dynamic stiffness on-track monitoring device comprises the following steps:

firstly, installing an SD card with a selected size in an SD card seat on a circuit board; secondly, the circuit board is tightly connected with the box body through 4M 3 bolts, the J30J-15ZK micro rectangular connector is arranged on a J30J-15ZK micro rectangular connecting interface on the box body, and the inner pin of the J30J-15ZK micro rectangular connector is connected with a 6 x 2 straight pin extension pin by a lead; finally, the top cover and the box body are tightly connected by using 4M 3 bolts.

The dynamic stiffness on-track monitoring device is connected through an interface:

firstly, connecting a JTAG simulator to a 4 x 1 recurved pin header, burning a program in a dynamic stiffness on-track monitoring device, and pulling out the JTAG simulator after the program burning is finished; then, the dynamic stiffness in-orbit monitoring device is installed on a spacecraft wall plate by using 4M 3 bolts, and the dynamic stiffness in-orbit monitoring device is connected with the spacecraft by using a USB (universal serial bus) wire through a USB interface, so that electrical connection and communication connection are realized; and finally, connecting an excitation signal output from the SMA interface to a piezoelectric driver on the inflatable deployable support structure, connecting a piezoelectric sensor on the inflatable deployable support structure to an interface of the J30J-15ZK micro rectangular connector, and simultaneously monitoring the dynamic stiffness of the 2-path inflatable deployable support structure by using the on-track monitoring device for the dynamic stiffness. An inflatable expandable support rod shown in fig. 5 is taken as an example, the inflatable expandable support rod is formed by bonding polyimide films with the thickness of 0.5mm, the upper top seat and the lower top seat and the base seat are both formed by printing PLA materials, the rod height is 700mm, the outer diameter is 100mm, 1 piezoelectric sheet driver and 2 piezoelectric sheet sensors are arranged on the films, the piezoelectric sheet driver is used for receiving sine frequency sweep signals output by a dynamic stiffness on-track monitoring device so as to excite the inflatable expandable support rod, the piezoelectric sheet sensors are used for converting the vibration of the inflatable expandable support rod into charge signals, the piezoelectric sheet driver on the inflatable expandable support rod outputs 1-10Hz sine frequency sweep signals by using the dynamic stiffness on-track monitoring device, the sine frequency sweep signals and the charge signals generated by the 2 piezoelectric sheet sensors are acquired with the resolution of 100Hz, short-time Fourier transform is respectively carried out on the signals, and the ratio is obtained, the dynamic stiffness curve of the inflatable and expandable support bar can be obtained as shown in figure 6. As can be seen from the figure, the inflatable deployable supporting rod has the structure mass distribution which is not uniform due to the existence of the clamping ring for bonding the pressing film and the top seat at the top, 2 first-order natural frequencies exist, and the dynamic stiffness value of the inflatable deployable supporting rod obtains minimum values at the first-order natural frequencies of 4.98Hz and 5.81 Hz.

The dynamic stiffness monitoring device can continuously measure the dynamic stiffness of the inflatable expandable support structure at fixed intervals, and the specific measuring process is as follows:

step 1: after the inflatable expandable support structure is expanded, the satellite-borne computer sends a starting measurement instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the signal generating module, the signal collecting module and the data storage module at intervals of a designated period, starts 2 excitation channels, and starts a timer TIM3 and a timer TIM 4;

step 3: the microprocessor module sends a frequency control word corresponding to the specified frequency to the signal sending module in an interrupt function generated by the timer TIM3 in an SPI communication mode, so that the microprocessor module generates a sinusoidal signal of the specified frequency according to the frequency control word and enables the signal acquisition module to acquire data in the interrupt function generated by the timer 4;

step 4: after the acquisition is finished, the microprocessor module respectively carries out short-time Fourier transform on the acquired excitation signal and response signal, obtains dynamic stiffness data of the inflatable expandable support structure by calculating the ratio of the excitation signal and the response signal, and then transmits the dynamic stiffness data to the SD card for storage;

step 5: after the data storage is finished, the microprocessor module enables the signal generation module, the signal acquisition module and the data storage module to enter a sleep mode to wait for the start of the next measurement.

The dynamic stiffness on-orbit monitoring device has a data storage function, does not need to occupy the storage space of the satellite borne computer, and only needs to transmit dynamic stiffness data to the satellite borne computer according to a data transmission instruction sent by the satellite borne computer, wherein the specific data transmission process is as follows:

step 1: the on-board computer sends a data transmission instruction to the dynamic stiffness on-orbit monitoring device;

step 2: the microprocessor module initializes the data storage module and the serial port communication module;

step 3: the microprocessor module reads data in the SD card and sends the data to the spaceborne computer through the USB;

step 4: after the data transmission task is finished, enabling the data storage module and the serial port communication module to enter a sleep mode by the microprocessor module;

step 5: and after receiving the dynamic stiffness data, the onboard computer sends the data to the ground.