STIM300-based position attitude measurement system algorithm verification device

Abstract

The invention discloses a position attitude measurement system algorithm verification device based on STIM300, and relates to the technical field of position attitude measurement. Comprising an inertial measurement module, a level conversion circuit, a mode switching circuit, a GNSS board card, an MCU, a high-precision temperature compensation crystal oscillator and a storage module which are connected in sequence, angular rate data, acceleration data and inclination angle data are collected for level conversion, and the working mode of the position attitude measurement system is switched through the mode switching circuit; the GNSS board card is used for providing positioning and orientation data and PPS signals for the position and attitude measurement system, receiving event trigger signals and outputting positioning data with timestamps; the MCU is used for acquiring positioning and orientation data and PPS signals output by the GNSS board card and clock pulse signals output by the high-precision temperature-compensation crystal oscillator through a serial port and running a combined navigation algorithm; and the high-temperature temperature compensation crystal oscillator outputs a clock pulse signal to the MCU. The invention provides a hardware platform for the influence of the time synchronization precision on the integrated navigation precision.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of pose measurement, in particular to a position and attitude measurement system algorithm verification device based on STIM300. BACKGROUND

[0002] The position and attitude measurement system is a kind of integrated navigation system, compared with the traditional integrated navigation system, the position and attitude measurement system requires high output frequency and high precision, and most of the products currently applied in the market are foreign brands, and there are fewer domestic self-research manufacturers with core technology, and the precision, stability and ease of use still have certain gap compared with foreign products. Since the position and attitude measurement system involves more technologies, and the cost of developing a set of position and attitude measurement system is high, more manufacturers and researchers tend to develop and research the integrated navigation algorithm, but such research results are based on simulation data or offline inertial measurement unit and GNSS positioning data for post-processing calculation, and cannot completely and truly reflect the effectiveness of the algorithm, especially the real-time integrated algorithm, because the real-time system may have certain outliers and GPS loss during operation, and has certain randomness, therefore, real and original experimental data are needed for verification, which needs a general position and attitude measurement system hardware platform for verifying the integrated navigation algorithm. There is no such hardware platform in the prior art, in addition, most of the position and attitude measurement system products currently seen do not have time synchronization function, and some have time synchronization function, but the synchronization precision is low, even if a high-precision inertial measurement unit is used, the ideal precision cannot be achieved, therefore, for the technical personnel in the field, how to design a reliable hardware system for verifying the function and precision of the integrated navigation algorithm is an urgent problem to be solved. SUMMARY

[0003] The purpose of the application is to provide a position and attitude measurement system algorithm verification device based on STIM300, to solve the problems in the background art, fill the blank of the domestic position and attitude measurement system algorithm verification device, and provide a reliable hardware system for algorithm developers to facilitate the verification of the function and precision of the integrated navigation algorithm.

[0004] To achieve the above purpose, the application provides the following scheme: a position and attitude measurement system algorithm verification device based on STIM300, comprising an inertial measurement module, a level conversion circuit, a mode switching circuit, a GNSS board card, an MCU, a high-precision temperature compensation crystal oscillator and a storage module; the inertial measurement module is connected with the level conversion circuit, the level conversion circuit is connected with the mode switching circuit, the mode switching circuit is connected with the MCU through the GNSS board card, and the MCU is connected with the high-precision temperature compensation crystal oscillator and the storage module respectively; wherein,

[0005] The inertial measurement module is configured to collect angular rate data, acceleration data, and inclination data.

[0006] The level conversion circuit is configured to perform level conversion on the data collected by the inertial measurement module.

[0007] The mode switching circuit is configured to receive the converted data from the level conversion circuit and switch the working mode of the position and attitude measurement system.

[0008] The GNSS board is configured to provide positioning and orientation data and a PPS signal for the position and attitude measurement system, receive event trigger signals EVENT1 and EVENT2, and output the positioning data with a time stamp.

[0009] The MCU is configured to obtain the positioning and orientation data and the PPS signal output by the GNSS board and the clock pulse signal output by the high-precision temperature-compensated crystal oscillator through a serial port, and run a combined navigation algorithm.

[0010] The high-temperature temperature-compensated crystal oscillator is configured to output a clock pulse signal to the MCU.

[0011] The storage module is configured to store the data obtained during the algorithm verification process of the position and attitude measurement system.

[0012] Preferably, the inertial measurement module is STIM300.

[0013] Preferably, the power management module is connected to the MCU and includes a reverse connection protection circuit and a soft start circuit.

[0014] Preferably, the interface expansion module is connected to the MCU and is configured to expand the MCU interface.

[0015] Preferably, the mode switching circuit changes the working mode of the position and attitude measurement system by changing the signal connection path of the STIM300, the GNSS board, and the MCU.

[0016] Preferably, the storage module is a TF card.

[0017] Preferably, the working mode includes an official mode and a self-developed mode. In the official mode, the STIM300 directly interacts with the GNSS board, and in the self-developed mode, all signals of the STIM300 are processed by the level conversion circuit and the mode switching circuit and then interact with the MCU, so that the MCU realizes time synchronization, data collection of the STIM300 and the GNSS board, and execution of a combined navigation algorithm, and the output results and the original data are stored in the TF card.

[0018] Preferably, the reverse connection protection and soft start circuit is built by using FDS9958 double-path P-channel MOS tube chip.

[0019] Preferably, the GNSS board card power supply circuit connected with the GNSS board card is further included, and the GNSS board card is powered by using MPS1584 as a switching power supply chip in the GNSS board card power supply circuit.

[0020] According to the specific embodiments provided by the application, the following technical effects are disclosed:

[0021] (1) The application integrates three working modes in a hardware design, which is convenient for developers to use, and can at least ensure that the navigation system can correctly run, even if the algorithm of the developer is not mature, the official mode can be switched through the mode switch, and the system can ensure that the navigation result can be correctly output.

[0022] (2) In the self-research mode, in addition to providing the developer with the verification work of the navigation algorithm in the hardware "reproduction" mode, the hardware platform for the developer to provide the influence of time synchronization accuracy on the integrated navigation accuracy is also provided, in the self-research algorithm verification mode, the time synchronization algorithm is designed by the developer, the influence of the time synchronization accuracy on the navigation accuracy can be verified by changing the time synchronization accuracy for many times.

[0023] (3) The scheme can also be applied to other types of IMU and GNSS board cards, and has strong applicability. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0025] Figure 1 It is a device structure diagram of the application;

[0026] Figure 2 It is a reverse connection protection and soft start circuit diagram of the application;

[0027] Figure 3 It is a GNSS board card power supply circuit diagram of the application;

[0028] Figure 4 It is a high-precision temperature compensation crystal oscillator peripheral circuit diagram of the application;

[0029] Figure 5 It is a level conversion and mode switching circuit diagram of the application;

[0030] Figure 6 This is a circuit diagram of the serial port signal level conversion of the present invention;

[0031] Figure 7 This invention relates to the EVENT signal protection circuit. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The purpose of this invention is to provide an algorithm verification device for a position and attitude measurement system based on STIM300, such as... Figure 1 As shown, it includes an inertial measurement module, a level conversion circuit, a mode switching circuit, a GNSS board, an MCU, a high-precision temperature-compensated crystal oscillator, and a storage module. The inertial measurement module is connected to the level conversion circuit, which is connected to the mode switching circuit. The mode switching circuit is connected to the MCU via the GNSS board. The MCU is connected to the high-precision temperature-compensated crystal oscillator and the storage module, respectively.

[0034] The inertial measurement module is used to collect angular rate data, acceleration data, and tilt angle data;

[0035] The level conversion circuit is used to convert the level of the data acquired by the inertial measurement module.

[0036] The mode switching circuit is used to receive the conversion data from the level conversion circuit and switch the working mode of the position and attitude measurement system.

[0037] The GNSS board is used to provide positioning and orientation data and PPS signals for the position and attitude measurement system, and to receive event trigger signals EVENT1 and EVENT2, and output positioning data with timestamps.

[0038] The MCU is used to acquire the positioning and orientation data, PPS signal, and clock pulse signal output by the GNSS board and the high-precision temperature-compensated crystal oscillator via the serial port, and to run the integrated navigation algorithm.

[0039] High-temperature compensated crystal oscillator, used to output clock pulse signals to MCU;

[0040] The storage module is used to store the data generated during the algorithm verification process of the position and attitude measurement system.

[0041] Further, in the embodiment, the inertial measurement module is STIM300, and the storage module is a TF card. The STIM300 can provide three angular rate data, three acceleration data and three inclination data for a position and attitude measurement system, has an RS422 data interface, can provide a data synchronization signal TOV, and can receive an external trigger signal ExtTrig. The level conversion circuit is used for converting the RS422 signal of the STIM300 transmission data into a single-ended LVTTL level serial signal, and converting the 5V level data synchronization signal TOV and the external trigger signal ExtTrig into a 3.3V LVTTL level signal, so as to be connected to a GNSS board card or an MCU through a mode switching circuit subsequently. The mode switching circuit is mainly used for switching the working mode of the whole position and attitude measurement system, and the signal connection path of the STIM300, the GNSS board card and the MCU is changed through a switching switch, a jumper or a 0-ohm resistor, so as to change the working mode of the position and attitude measurement system.

[0042] The GNSS board card mainly provides high-precision positioning and orientation data and a PPS signal for the position and attitude measurement system, and receives event trigger signals EVENT1 and EVENT2, and outputs the positioning data with a time stamp.

[0043] The MCU mainly runs a combined navigation algorithm developed by a developer: the positioning and orientation data (including the positioning data with a time stamp) output by the GNSS board card are acquired through a serial port; a high-precision time synchronization signal IMU_TRIGERMCU (converted into a 5V ExtTrig signal through a level conversion circuit) is provided through the PPS signal output by the GNSS board card and the clock pulse signal output by a high-precision temperature compensation crystal oscillator, and is used for triggering the data acquisition of the STIM300 and the combined navigation calculation; in addition, the MCU also receives the TOV signal (converted into a 3.3V IMU_TOVMCU signal through a level conversion circuit) output by the STIM300, and synchronously outputs an event signal EVENT1 to the GNSS board card, and the GNSS board card outputs the positioning data with time stamp information to the MCU through the serial port, which is used for the combined navigation algorithm.

[0044] In addition, the MCU also connects the TF card through an SDIO interface, and stores the positioning data output by the GNSS board card and the IMU original data into the TF card, which is convenient for subsequent offline processing.

[0045] Further, a power management module is further included, which is connected with the MCU, and includes a reverse connection protection and soft start circuit and various secondary voltage power supplies (including a 3.3V voltage required by the MCU and the GNSS board card, and a 5V voltage required by the IMU). The reverse connection protection and soft start circuit is calculated according to the system power supply voltage range and current, such as Figure 2As shown, the FDS9958 double-path P-channel MOS tube chip is used in the application for reverse connection protection and soft start circuit, specifically: when the power supply is normally connected, the bias current flows through the built-in diode of the second-path MOS tube of the chip, flows through R13 and R14 to return to the input end, the voltage drop across R13 is the gate-source control voltage of the two-path MOS tube, due to the existence of capacitor C18, this voltage will gradually decrease (note that this voltage is negative), when the MOS tube's on-resistance gradually decreases, the soft start function is realized; when the input voltage is reversely connected, the built-in diode of the second-path MOS tube is in reverse bias state, there is no bias current in the circuit, and the circuit does not work, thereby achieving the reverse connection protection function; due to the existence of certain error in the input voltage, and considering that the input voltage can be wide voltage, in order to make the on-resistance of the MOS tube minimum when it is turned on, the values of R13, R14, C18 and D1 can be changed to achieve the ideal turn-on voltage.

[0046] Further, the interface expansion module is connected with the MCU, and is used for performing MCU interface expansion.

[0047] Further, as shown in Figure 3 Further, the GNSS board card power supply circuit is connected with the GNSS board card; and the MPS1584 is used as a switching power supply chip to supply power to the GNSS board card in the GNSS board card power supply circuit.

[0048] Further, most of the current position and attitude measurement system products do not have the function of time synchronization, and some have the function of time synchronization, but the synchronization accuracy is low, even if a high-precision inertial measurement unit is used, the ideal precision cannot be achieved, therefore, the application also designs a time synchronization hardware circuit, and a high-precision temperature-compensated crystal oscillator is added in the circuit, as shown in Figure 4 The clock signal output by the high-precision temperature-compensated crystal oscillator is counted / timed, the timing accuracy is higher compared with the timer built in the MCU, and the PPS signal of the GNSS board card is introduced into the MCU, which is used for real-time correction of the error of the high-precision temperature-compensated crystal oscillator clock, the synchronization accuracy is greatly improved, and the final integrated navigation precision can be effectively improved.

[0049] As shown in Figure 5 The level conversion and mode switching circuit diagram of the two-path trigger signal of the application is shown, the level conversion adopts a double-path bidirectional level conversion chip, and the mode switching is changed by the code switch SW1. The mode switching circuit changes the signal connection path of the STIM300, the GNSS board card and the MCU to change the working mode of the position and attitude measurement system.

[0050] The GNSS board card and the inertial measurement module model are a typical combination of the Novatel integrated navigation system. Two algorithm verification methods can be realized. On the one hand, in the official mode, the GNSS board card has a Novatel official real-time integrated navigation algorithm, and can output all raw data to the MCU for storage in the storage module. After the user exports the raw data, the user uses the raw data as the input data of the self-developed real-time algorithm, compares the navigation output of the self-developed real-time algorithm with the official output result, and evaluates the correctness and precision of the self-developed real-time algorithm. On the other hand, in the self-developed mode, the user stores the angular velocity and acceleration data output by the time-synchronized inertial measurement module, the raw data output by the GNSS board card, and the navigation data output by the self-developed algorithm in the storage module. The user imports the angular velocity and acceleration output by the inertial measurement module and the raw data output by the GNSS board card into the Novatel official post-processing software, and can obtain the fused navigation data. The data is used as a reference to verify and evaluate the correctness and precision of the user's real-time navigation data.

[0051] Specifically, the position and attitude measurement system algorithm verification device has two working modes. One is the Novatel official integrated navigation, referred to as the official mode. In this mode, the STIM300 directly interacts with the GNSS board card. Specifically, the RS422 serial port signal used by the STIM300 to output data is converted to a 3.3V LVTTL level serial port signal, which is directly connected to the serial port of the GNSS board card (the GNSS board card designed in the embodiment of the application is a Novatel OEM7720, and the firmware supports a real-time integrated navigation algorithm). The TOV signal of the STIM300 is connected to the Event_In2 event signal of the GNSS board card. Through port configuration, the GNSS board card can output real-time integrated navigation data and raw data. The MCU communicates with the GNSS board card through a serial port (the serial port in the application is COM3), and stores the real-time integrated navigation data, GNSS positioning data, IMU raw data and the like output by the GNSS board card to a TF card.

[0052] The second mode is developed for real-time integrated navigation algorithm developers, and is referred to as a self-developed mode for convenience. In this mode, all signals of the STIM300 are converted to 3.3V levels by a level conversion circuit, and are all interacted with an MCU through a mode switching circuit. The MCU realizes time synchronization, STIM300 data acquisition, GNSS board data acquisition, and executes an integrated navigation algorithm to store output results and original data to a TF card. It should be noted that this mode includes two working modes: (1) a hardware "reproduction" mode of an official Novatel integrated navigation scheme. In this mode, the data output by the STIM300 is acquired by the MCU instead of the official GNSS board, and the TOV signal of the STIM300 is indirectly connected to the event signal EVENT1 of the GNSS board through the MCU instead of the official time signal EVENT2, so that the official scheme is perfectly replaced in hardware, that is, the hardware "reproduction" of the official integrated navigation scheme (since the TOV signal is indirectly connected to the event signal EVENT1 of the GNSS board through the MCU, it is not an equivalent replacement, but for the STIM300 used in this scheme, the time delay error caused by the indirect triggering of the MCU can be ignored). (2) a self-developed algorithm verification mode. In this mode, the MCU is a core controller, and the MCU can obtain a higher-precision synchronization signal IMU_TRIGER2MCU through a PPS signal and a clock pulse signal output by a high-precision temperature-compensated crystal oscillator, and actively triggers the data output of the STIM300. The frequency of integrated navigation calculation can be changed according to the actual scene, and the applicability is stronger.

[0053] As Figure 6 It is the TTL level serial port signal level conversion circuit diagram of the application, considering certain compatibility, the serial port level of some systems is 5V TTL level, and the serial port level of some systems is 3.3V. In order to maintain compatibility and save cost, a compatible circuit is designed. Specifically, for the serial port receiving signal, as shown in the figure, if the COM4_RXD_TTL signal is a 3.3V high level, the zener diode D7 in the figure does not work. Since the current in the circuit is very small (mA level or even smaller), the voltage division generated by R48 in the circuit is very small (the value of R48 can be adjusted according to the specific situation), which does not affect the recognition of the COM4_RXD_LVTTL high level. If the signal is a 5V high level, the zener diode D7 will embed the COM4_RXD_LVTTL to a 3.3V high level, and the 1.7 voltage difference will be shared by the resistor R48. If COM4_RXD_TTL is low, COM4_RXD_LVTTL will also be low. For the serial port sending signal, COM4_TXD_LVTTL is 3.3V level, which is converted to 5V level through a transistor circuit, and then R51 is compatible with 3.3V level.

[0054] As Figure 7 For the EVENT signal protection circuit of the application, since the GNSS board card is 3.3V level, in order to be compatible with the external 5V level event signal, the 5V level is converted into 3.3V level by means of series connection of resistance and voltage stabilizing diode.

[0055] The principles and implementation manners of the present application are described by applying specific examples in the present application, and the above description of the examples is only for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the field, according to the idea of the present application, the specific implementation manners and application ranges will have changes. In conclusion, the content of the present description should not be understood as the limitation of the present application.

Claims

1. A STIM300 based position and attitude measurement system algorithm verification apparatus, characterized by, Include inertial measurement module, level conversion circuit, mode switching circuit, GNSS board, MCU, high-precision temperature compensation crystal oscillator, storage module;The inertial measurement module is connected with the level conversion circuit, the level conversion circuit is connected with the mode switching circuit, the mode switching circuit is connected with the MCU through the GNSS board, the MCU is connected with the high-precision temperature compensation crystal oscillator and the storage module respectively;Among them, The inertial measurement module is used for collecting angular rate data, acceleration data and inclination data; The level conversion circuit is used for level conversion of the data collected by the inertial measurement module; The mode switching circuit is used for receiving the conversion data of the level conversion circuit, switching the working mode of the position and attitude measurement system; The GNSS board is used for providing positioning, orientation data and PPS signal for the position and attitude measurement system, receiving event trigger signal EVENT1 and EVENT2, and outputting positioning data with timestamp; The MCU is used for obtaining the positioning, orientation data and PPS signal output by the GNSS board and the clock pulse signal output by the high-precision temperature compensation crystal oscillator through the serial port, and running the integrated navigation algorithm; The high-temperature temperature compensation crystal oscillator is used for outputting the clock pulse signal to the MCU; The storage module is used for storing the data running in the algorithm verification process of the position and attitude measurement system.

2. The STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 1, wherein, The inertial measurement module is STIM300.

3. The STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 1, wherein, It also includes a power management module connected with the MCU, including reverse connection protection and soft start circuit.

4. The STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 1, wherein, It also includes an interface expansion module connected with the MCU for MCU interface expansion.

5. The STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 2, wherein, The mode switching circuit changes the working mode of the position and attitude measurement system by changing the signal connection path of STIM300 and the GNSS board and the MCU.

6. The STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 1, wherein, The storage module is a TF card.

7. A STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 6, wherein, The working mode includes official mode and self-developed mode;In the official mode, the STIM300 directly interacts with the GNSS board;In the self-developed mode, all signals of the STIM300 are processed by the level conversion circuit and the mode switching circuit, and then interact with the MCU, which realizes time synchronization, STIM300 and GNSS board data acquisition by the MCU, and executes integrated navigation algorithm, and stores the output results and original data to TF card.

8. The STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 3, wherein, FDS9958 dual-channel P-channel MOS chip is used to build the reverse connection protection and soft start circuit.

9. The STIM300 based position and attitude measurement system algorithm verification apparatus according to claim 1, wherein, It also includes a GNSS board power supply circuit connected with the GNSS board; MPS1584 is used as a switching power supply chip in the GNSS board power supply circuit to supply power to the GNSS board.

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