A dynamic closed-loop ignition control method and device for a dual-pulse solid rocket engine

Abstract

The present invention provides a dual-pulse solid rocket engine dynamic closed-loop ignition control method and device, which uses a pressure sensor to measure the working pressure of the first-stage engine, and the output signal is monitored by the multi-channel AD on the chip of the DSP after passing through different operational amplifier circuits; when the collected signal drops to a set threshold, the timing starts, and after the set time is reached, the DSP outputs a signal to start the secondary ignition circuit. The present invention has high control accuracy, short delay time, stable operation, simple operation, and can accurately complete the ignition control instruction. Through modular combination, it can also realize dynamic closed-loop ignition control of multi-stage solid rocket engines.

Description

Technical Field

[0001] The invention belongs to the field of aerospace technology, and in particular relates to a test method for ignition control of a rocket engine. Background Art

[0002] A certain type of solid rocket engine adopts a dual-pulse engine structure. The two-stage pulse engines have separate igniters, and the ignition time of the two-stage pulse engines is controlled by the onboard computer. According to the overall requirements, the ignition time intervals of the I and II pulse engines in the ground static test of the dual-pulse solid rocket engine are 0s, 12s, 24s, 48s, and 60s respectively, and the ignition time of the II pulse should be controlled by the pressure measured during the operation of the I pulse.

[0003] The existing engine ignition device uses the timing signal as the time zero point and uses the time relay timing method to start the two-stage ignition in sequence. This ignition method has a simple structure and stable operation, but it cannot simulate the ignition state of the actual engine to dynamically control the start of the two-stage ignition, and the control accuracy is not high. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a dynamic closed-loop ignition control method for a dual-pulse solid rocket engine. The pressure measured during the first-stage operation is used as a control signal to start the second-stage ignition, thereby realizing dynamic control of the second-stage ignition of the engine. The present invention has high control accuracy, short delay time, stable operation, and simple operation. It can accurately complete the ignition control instructions, and can also realize dynamic closed-loop ignition control of multi-stage solid rocket engines through modular combination.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a dynamic closed-loop ignition control method for a dual-pulse solid rocket engine, which collects the working pressure of the first-stage engine, and performs multi-channel segmented real-time collection of the obtained first-stage engine working pressure signal. When the collected signal drops to a set threshold, the timing starts, and the second-stage ignition is started after the set time is reached.

[0006] A time period is set before the set duration to interpret the collected signal, a software lock is set to lock the pressure in the rising stage of the first-stage engine, and the software lock is unlocked after the first-stage engine enters a stable state, and the timing starts when the collected pressure signal is in the falling stage and drops to the set threshold.

[0007] The present invention also provides a dual-pulse solid rocket engine dynamic closed-loop ignition control device for implementing the above method, comprising a pressure sensor, a DSP and a secondary ignition circuit.

[0008] The pressure sensor measures the working pressure of the first-stage engine. After the output signal passes through different operational amplifier circuits, the signal is monitored by the on-chip multi-channel AD of the DSP. When the collected signal drops to a set threshold, the timing starts. After the set time is reached, the DSP outputs a signal to start the second-stage ignition circuit.

[0009] The DSP scans the analog signal output end of the pressure sensor in a query manner and performs filtering using the IIR low-pass filtering algorithm built into the DSP.

[0010] The GPIO pin of the DSP outputs a high level to turn on the relay of the secondary ignition circuit, thereby triggering the secondary ignition.

[0011] The pressure sensor measures the pressure signal during the operation of the first-stage engine, outputs a 0-3V voltage signal through an amplifier, and after passing through different operational amplifier circuits, the signal is monitored by the on-chip multi-channel AD of the DSP; the collected 0-3V voltage signal is divided into two sections, namely 0-600mV and 600mV-3V, which are respectively input into two groups of collection circuits, one group uses a voltage follower for signal isolation, and the signal itself is not amplified, and this channel is used for AD collection of 600mV-3V signals; the other group uses a 4x amplification circuit to amplify the small signal voltage value of 0-600mV by 4 times before AD collection.

[0012] The DSP is provided with a protection diode at the AD port to prevent the voltage at the AD input port from being too large.

[0013] The beneficial effects of the present invention are: using DSP as the core control chip of the system, the external crystal oscillator can reach 30MHz, and the working speed is fast. With this technology as the core, a dynamic multi-stage ignition control device based on DSP acquisition, control program design and upper computer application program interface is constructed, realizing a certain model of multi-stage dynamic ignition control, solving the technical problem of the consistency of the dual-pulse dynamic ignition control of the model solid rocket engine, ensuring the safety and reliability of the engine ignition, and improving the control accuracy. The present invention uses a resistive touch LCD screen as the operation interface of the ignition system, realizing system calibration, parameter setting, and display of the pressure curve during ignition, and through real-time acquisition of the first-stage engine working pressure, the first-stage working pressure setting value is used as the second-stage engine ignition start signal to simulate the actual working condition of the dual-pulse solid rocket engine and realize dynamic control ignition; the system sets a software lock, which can be set according to the engine working time to avoid mis-ignition caused by the jitter of the pressure measurement signal in the rising section; the sampling data is filtered by a filtering algorithm, and the system is guaranteed to accurately and quickly judge the moment when the pressure signal drops to the predetermined pressure value by adopting the method of recording the average value of multiple segments of data.

[0014] There is no relevant research in China at present. The present invention not only studies the test method, but also designs a dynamic ignition control device, which can realize system calibration, automatic signal collection, and use the pressure measured during the first-stage working process as a control signal to start the second-stage ignition, thereby realizing dynamic control of the second-stage ignition of the engine. The system has high control accuracy, short delay time, stable operation, simple operation, and various technical indicators can meet the design requirements. In addition, the system is modularly designed, and can perform multi-stage ignition after development according to the needs of model development and production tasks. It has strong scalability and can meet the requirements of ignition of various models of solid rocket engines. Through the present invention, a method based on the combination of DSP and pressure sensor control is mastered, and a dynamic ignition control method for a dual-pulse solid rocket engine is formed, which fills the gap in the field of dynamic ignition control technology of domestic dual-pulse solid rocket engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flow chart of DSP acquisition and control program design;

[0016] Figure 2 It is the pressure signal measurement circuit diagram;

[0017] Figure 3 It is a primary ignition circuit diagram;

[0018] Figure 4 It is a secondary ignition circuit diagram. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The present invention includes but is not limited to the following embodiments.

[0020] The present invention discloses a software and hardware control method that uses DSP as the system core control chip and is combined with a pressure signal device. The present invention selects a DSP of the 2000 series model TMS320F28335 as the system core control chip, inputs the first-stage engine working pressure signal into the system signal processing unit through a pressure sensor or a pressure transmitter, processes the pressure measurement signal, and sends it to the AD of the DSP for multi-channel segmented real-time acquisition, and displays the measured pressure signal curve in real time on the control interface. When the pressure measurement signal drops to a predetermined pressure value P (0.3MPa-5MPa), a mark line appears on the control interface, and the DSP starts timing. After the timing is t seconds, the buzzer alarms and the second-stage ignition is started, thereby realizing the dynamic control of the second-stage ignition of the engine.

[0021] The invention is based on DSP acquisition, control program design and host computer application program interface design. It is written in Visual Studio 2008 software and communicates with DSP through CAN bus to achieve system calibration, parameter setting, display, etc.

[0022] The pressure sensor calibration is completed by manual calibration on the host computer interface. The return number and calibration points should be set before calibration. At least two calibration points are required during the calibration process, and the maximum and minimum voltage values ​​of the calibration must be between 0 and 0.6V and 0.6V and 3V respectively after passing through the amplifier, otherwise the system will not work properly or work abnormally. For sensors whose maximum output of the range still cannot reach 0.6V after the op amp, the maximum output can be changed by adjusting the voltage divider resistor in the chassis.

[0023] DSP completes the self-check of the control circuit, mainly including: DSP working status, system voltage contacts, etc. After the self-check is normal, the operator enters the authorization code and enters the parameter setting. The parameters mainly include: preset pressure value P, delay time T (I, II pulse engine ignition time interval). DSP reads the configuration information and enters the working state. When the time arrives, DSP scans the analog signal output end of the pressure sensor in a query manner, and uses the built-in IIR low-pass filter algorithm of DSP to filter to ensure the stability and reliability of the signal. In order to increase the high reliability of system communication, after all parameters are set, the preset pressure value will be displayed on the LCD screen of the lower computer. The pressure value is judged 10ms before the delay time T. Because the pressure signal has jitter in the rising section during the first-stage ignition of the solid rocket engine, the system uses a software lock, sampling 10ms, and the software lock is automatically opened when the engine enters a stable state. The software lock can avoid mis-ignition caused by jitter of the pressure signal. When the first-stage ignition of the engine is about to be completed, when the measured pressure value is in the descending stage and is equal to the predetermined pressure value P, the DSP is triggered to enter the second-stage ignition countdown. According to the set delay time t seconds, after the delay is over, the GPIO pin of the DSP outputs a high level to turn on the relay of the second-stage ignition circuit, triggering the second-stage ignition.

[0024] DSP acquisition and control program design process Figure 1 shown.

[0025] The pressure signal measuring circuit of the present invention is as follows Figure 2As shown, the invention uses a pressure sensor to measure the pressure signal during the first stage of the engine operation, and outputs a 0-3V voltage signal through an amplifier. After passing through different operational amplifier circuits, the signal is monitored by the multi-channel AD on the DSP chip. The DSP has an on-chip 12-bit AD, and the analog signal acquisition resolution is 0.7mV. Therefore, when measuring small signals at the millivolt level, the accuracy cannot meet the requirements. In order to further improve the acquisition accuracy, the system divides the collected 0-3V voltage signal into two sections, namely 0-600mV and 600mV-3V, and uses a multi-channel AD switching method to acquire the pressure signal. The system inputs the voltage signal into two groups of acquisition circuits respectively. One group uses a voltage follower for signal isolation. The signal itself is not amplified. This channel is used for AD acquisition of 600mV-3V signals; the other group uses a 4x amplifier circuit to amplify the small signal voltage value of 0-600mV by 4 times before AD acquisition, thereby improving the acquisition accuracy of small signals. The segmented recognition of the signal is completed by the system software.

[0026] The signal processing and control circuit of the present invention adopts DSP of 2000 series model TMS320F28335 as the system core control chip, and the external crystal oscillator can reach 30MHz, and the working speed is fast.

[0027] 1) Two AD channels are used to collect the 0-3V voltage signal output by the amplifier, and another 4 AD channels are used to monitor the system voltage nodes 24V, 5V, 3.3V, and GND in real time. When the voltage is abnormal, the system will send out an alarm signal;

[0028] 2) The AD port is equipped with a protection diode to prevent the AD input port voltage from being too high and burning the chip;

[0029] 3) When the DSP detects that the pressure signal has dropped to the preset pressure value P, it counts t seconds and outputs a 3.3V high-level signal through the GPIO pin to start the secondary ignition of the engine.

[0030] According to the ignition mode requirements of the dual-pulse solid rocket engine, the ignition control system of the present invention is provided with level I and level II ignition circuits. Each level of ignition can be divided into two independent ignition circuits for ignition of two igniters.

[0031] The first-stage ignition circuit is started by the timing signal sent by the sub-control box. When the timing signal arrives, the relay switch is closed, the ignition circuit is turned on, and the first-stage ignition is started. Figure 3 YS1 is the ignition key switch, which is closed before the timing signal arrives, ensuring the safety and reliability of the first-stage ignition.

[0032] The secondary ignition circuit is started by DSP control. During the operation of the first-stage engine, the system software lock starts the DSP to collect the first-stage pressure signal in real time. When the second-stage ignition requirements are met, a 3.3V high-level signal is output through the GPIO pin, the three-stage tube is turned on, the relay switch is closed, and the second-stage ignition is started. The circuit is as follows Figure 4 YS2 is a two-stage ignition key switch, which ensures the safety and reliability of two-stage ignition.

[0033] 1) Both the two-stage ignition circuits are equipped with a circuit conduction circuit. Before the test, the circuit conduction current can be used to detect whether the engine ignition circuit is normal;

[0034] 2) The secondary ignition circuit is equipped with a manual ignition key switch YS3 to ensure safe and reliable secondary ignition.

[0035] 3) The ignition circuit is equipped with an emergency stop circuit to terminate the ignition test when an abnormal situation occurs.

Claims

1. A dynamic closed-loop ignition control method for a dual-pulse solid rocket engine, characterized in that: The following steps are involved: The working pressure of the first-stage engine is collected, and the obtained working pressure signal of the first-stage engine is collected in real time in a multi-channel segmented manner. When the collected signal drops to a set threshold, timing starts, and the second-stage ignition is started after the set time is reached; a time period is set before the set time to interpret the collected signal, a software lock is set to lock the pressure in the rising stage of the first-stage engine, and the software lock is unlocked after the first-stage engine enters a stable state, and timing starts when the collected pressure signal is in a falling stage and drops to a set threshold.

2. A dual-pulse solid rocket engine dynamic closed-loop ignition control device for implementing the method described in claim 1, comprising a pressure sensor, a DSP and a secondary ignition circuit, characterized in that: The pressure sensor measures the working pressure of the first-stage engine. After the output signal passes through different operational amplifier circuits, the signal is monitored by the on-chip multi-channel AD of the DSP. When the collected signal drops to a set threshold, the timing starts. After the set time is reached, the DSP outputs a signal to start the second-stage ignition circuit.

3. The dual-pulse solid rocket engine dynamic closed-loop ignition control device according to claim 2, characterized in that: The DSP scans the analog signal output end of the pressure sensor in a query manner and performs filtering using the IIR low-pass filtering algorithm built into the DSP.

4. The dual-pulse solid rocket engine dynamic closed-loop ignition control device according to claim 2, characterized in that: The GPIO pin of the DSP outputs a high level to turn on the relay of the secondary ignition circuit, thereby triggering the secondary ignition.

5. The dual-pulse solid rocket engine dynamic closed-loop ignition control device according to claim 2, characterized in that: The pressure sensor measures the pressure signal during the operation of the first-stage engine, outputs a 0-3V voltage signal through an amplifier, and after passing through different operational amplifier circuits, the signal is monitored by the on-chip multi-channel AD of the DSP; the collected 0-3V voltage signal is divided into two sections, namely 0-600mV and 600mV-3V, which are respectively input into two groups of collection circuits, one group uses a voltage follower for signal isolation, and the signal itself is not amplified, and this channel is used for AD collection of 600mV-3V signals; the other group uses a 4x amplification circuit to amplify the small signal voltage value of 0-600mV by 4 times before AD collection.

6. The dual-pulse solid rocket engine dynamic closed-loop ignition control device according to claim 2, characterized in that: The DSP is provided with a protection diode at the AD port to prevent the voltage at the AD input port from being too large.

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