Pseudo-satellite-based indoor and outdoor integrated positioning system for vehicle in semi-shielded plant

Abstract

The invention relates to a semi-shielded plant vehicle indoor and outdoor integrated positioning system based on pseudo satellites. The system comprises an indoor Beidou satellite master transmitter, an indoor Beidou satellite slave transmitter and a vehicle-mounted positioning terminal. The indoor Beidou satellite main transmitter is arranged in the semi-shielded plant, the semi-shielded plant is of a metal ceiling structure, and part of the ceiling is made of a non-metal material; the indoor Beidou satellite main transmitter comprises a power supply module, a control module, a wireless frequency synchronization module transmitting end, a satellite PPS time service module, a PPS taming crystal oscillator, a wireless communication module and a pseudo satellite transmitting module, and is set as a pseudo satellite positioning multiple modularized structure; the PPS synchronization, stable clock, power supply and communication conditions necessary for pseudo-satellite positioning are met, the problem of difficult construction and installation is solved, a more optimized deployment effect and lower implementation cost are achieved, application and popularization of the pseudo-satellite positioning technology are facilitated, and on-site installation and debugging are facilitated due to modular arrangement.

Description

Technical Field

[0001] The present invention relates to the field of indoor pseudo-satellite positioning, and in particular to a pseudo-satellite-based indoor and outdoor integrated positioning system for semi-sheltered workshop vehicles. Background Art

[0002] Currently, among the existing indoor positioning technologies, UWB, Bluetooth, ZigBee, WIFI and other technologies can all achieve indoor positioning effects with a certain degree of accuracy. However, each of the above technologies operates independently, manufacturers are isolated from each other, devices are separated from each other, and there is no universal protocol standard. They can only meet the needs of specific groups of people and cannot adapt to existing users.

[0003] Pseudolite technology involves transmitting navigation signals similar to those of the Beidou system or other GNSS systems from a specific location on the ground. By using the same carrier wave, coding method, modulation method, and message format as those used outdoors, combined with the actual satellite positions in the current constellation, pseudorange, Doppler and other parameters are simulated. This artificially simulates satellite signals and subsequently achieves terminal positioning.

[0004] Because the user's satellite positioning receiver does not distinguish whether the signal is simulated or naturally received, it will receive the signal and achieve positioning through specific solutions.

[0005] However, in actual deployment, to ensure integrated indoor and outdoor reception, the pseudolite signals broadcast by the transmitter must be strictly synchronized with the outdoor signal. This typically requires a PPS synchronization accuracy better than 5ns, and a clock stability better than 10^-12s. This, combined with power supply and communication requirements, places high demands on construction and installation. This hinders the application and promotion of pseudolite positioning technology. Summary of the Invention

[0006] The purpose of the present invention is to provide a pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles, so as to solve the problems existing in the above-mentioned prior art.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions: The pseudo-satellite-based indoor and outdoor integrated positioning system for semi-sheltered factory vehicles includes an indoor Beidou satellite master transmitter, an indoor Beidou satellite slave transmitter, and a vehicle-mounted positioning terminal. The indoor Beidou satellite main transmitter is arranged inside a semi-sheltered factory building, and the semi-sheltered factory building has a metal roof structure, and part of the roof is made of non-metallic materials; The indoor Beidou satellite main transmitter includes a power module, a control module, a wireless frequency synchronization module transmitting end, a satellite PPS timing module, a PPS taming crystal oscillator, a wireless communication module and a pseudo-satellite transmitting module. The power module, PPS taming crystal oscillator, wireless communication module and pseudo-satellite transmitting module are all electrically connected to the control module by signal, and the wireless frequency synchronization module transmitting end and the satellite PPS timing module are both electrically connected to the PPS taming crystal oscillator by signal.

[0008] By adopting the above technical solution, the indoor Beidou satellite main transmitter is set as a multiple modular structure for pseudo-satellite positioning. While meeting the PPS synchronization, stable clock, power supply and communication conditions necessary for pseudo-satellite positioning, it also solves the problem of difficult construction and installation, achieving a more optimized deployment effect and lower implementation cost, facilitating the application and promotion of pseudo-satellite positioning technology, and the modular setting is more conducive to on-site installation and debugging.

[0009] In a further embodiment, the control module is used to control the power supply module, the wireless frequency synchronization module transmitter, the satellite PPS timing module, the PPS taming crystal oscillator, the wireless communication module and the pseudo-satellite transmitting module; the PPS taming crystal oscillator is used to output a tamed crystal oscillator according to the input PPS pulse; the communication protocol of the wireless communication module is one of the WieWifi and Lora wireless protocols, and the wireless communication module is used for data transmission between base stations.

[0010] In a further embodiment, the power supply module is an ACDC step-down module or a DCDC step-down module, which is used to obtain AC or DC high-voltage current from the power supply cable, and after stepping down, to power the indoor Beidou satellite transmitter.

[0011] In a further embodiment, the transmitting end of the wireless frequency synchronization module transmits a radio signal of a set frequency based on a PPS disciplined crystal oscillator.

[0012] In a further embodiment, the satellite PPS timing module is used to receive satellite signals, and the satellite PPS timing module outputs PPS pulses.

[0013] In a further embodiment, the indoor Beidou satellite slave transmitter includes a power module, a control module, a wireless frequency synchronization module receiving end, a satellite PPS timing module, a wireless communication module, and a pseudo-satellite transmitting module; the wireless frequency synchronization module receiving end is used to receive the frequency signal of the wireless frequency synchronization module transmitting end in the indoor Beidou satellite main transmitter, and at the same time convert the signal into a stable frequency available to the slave transmitter through amplification, frequency division, and filtering.

[0014] In a further embodiment, the vehicle-mounted positioning terminal includes a power module, a satellite receiving module, a computing unit and a 4G / 5G communication module; the satellite receiving module is used to receive satellite signals from outdoor satellites and receive indoor pseudo-satellite signals at the same time.

[0015] In a further embodiment, the computing unit includes a portion disposed outdoors and a portion disposed indoors; In the outdoor part, the computing unit performs RTK positioning through a 4G / 5G communication module combined with an outdoor RTK differential reference station; In the indoor part, the original observation quantity of indoor pseudo-satellite signal is extracted and combined with the broadcast signal of pseudo-satellite to perform indoor position solution.

[0016] In a further embodiment, a 4G / 5G communication module enables wireless communication of vehicle-mounted equipment.

[0017] In summary, the present invention has the following beneficial effects: 1. The indoor BeiDou satellite main transmitter is set as a multiple modular structure for pseudolite positioning. While meeting the necessary PPS synchronization, stable clock, power supply, and communication conditions for pseudolite positioning, it also solves the problem of difficult construction and installation, achieving a more optimized deployment effect and lower implementation costs, facilitating the application and promotion of pseudolite positioning technology. The modular setting is more conducive to on-site installation and commissioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural block diagram of an indoor Beidou satellite slave transmitter embodying the present invention; Figure 2 It is a structural block diagram of an indoor Beidou satellite main transmitter embodying the present invention; Figure 3 It is a flowchart for the satellite PPS timing module embodying the present invention; Figure 4 It is a flowchart for embodying the master-slave base station synchronization timing of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below with reference to the accompanying drawings.

[0020] The same parts are denoted by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the attached Figure 1In the description, the terms "bottom" and "top," "inner" and "outer" refer to directions toward or away from a particular component geometry, respectively. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this specification, "plurality" means two or more, unless otherwise specifically defined in terms of the center's direction.

[0021] Example 1: like Figure 1-Figure 4 As shown, the pseudo-satellite-based indoor and outdoor integrated positioning system for semi-sheltered factory vehicles includes an indoor Beidou satellite master transmitter, an indoor Beidou satellite slave transmitter and a vehicle-mounted positioning terminal; The indoor Beidou satellite main transmitter is arranged inside a semi-sheltered factory building, and the semi-sheltered factory building has a metal roof structure, and part of the roof is made of non-metallic materials; The indoor Beidou satellite main transmitter includes a power module, a control module, a wireless frequency synchronization module transmitting end, a satellite PPS timing module, a PPS taming crystal oscillator, a wireless communication module and a pseudo-satellite transmitting module. The power module, the PPS taming crystal oscillator, the wireless communication module and the pseudo-satellite transmitting module are all connected to the control module by electrical signals, and the wireless frequency synchronization module transmitting end and the satellite PPS timing module are all connected to the PPS taming crystal oscillator by electrical signals; the control module is used to control the power module, the wireless frequency synchronization module transmitting end, the satellite PPS timing module, the PPS taming crystal oscillator, the wireless communication module and the pseudo-satellite transmitting module; the PPS taming crystal oscillator is used to output a tamed crystal oscillator according to the input PPS pulse; the communication protocol of the wireless communication module is one of the WieWifi and Lora wireless protocols, and the wireless communication module is used for data transmission between base stations; the power module is an ACDC step-down module or a DCDC step-down module, which is used to obtain AC or DC power from the power supply cable The high-voltage current flowing through is stepped down to supply energy to the indoor Beidou satellite transmitter; the transmitting end of the wireless frequency synchronization module uses the PPS disciplined crystal oscillator as a reference to transmit a radio signal of a set frequency; the satellite PPS timing module is used to receive satellite signals, and the satellite PPS timing module outputs PPS pulses; the indoor Beidou satellite slave transmitter includes a power module, a control module, a wireless frequency synchronization module receiving end, a satellite PPS timing module, a wireless communication module, and a pseudo-satellite transmitting module; the wireless frequency synchronization module receiving end is used to receive the frequency signal of the wireless frequency synchronization module transmitting end in the indoor Beidou satellite main transmitter, and at the same time, through amplification, frequency division, and filtering, the signal is converted into a stable frequency available from the transmitter; the vehicle-mounted positioning terminal includes a power module, a satellite receiving module, an operation unit and a 4G / 5G communication module; the satellite receiving module is used to receive satellite signals from outdoor satellites and receive indoor pseudo-satellite signals at the same time; the operation unit includes an outdoor part and an indoor part; In the outdoor part, the computing unit performs RTK positioning through a 4G / 5G communication module combined with an outdoor RTK differential reference station; In the indoor part, the original observation quantity of indoor pseudo-satellite signals is extracted and combined with the broadcast signals of pseudo-satellites to perform indoor position calculation; the 4G / 5G communication module realizes wireless communication of vehicle-mounted equipment.

[0022] like Figure 3 As shown in the workflow diagram of the satellite PPS timing module, since there are outdoor satellite signals and indoor pseudo-satellite signals broadcast indoors in the semi-shaded scene, the satellite PPS timing module should also strip off the indoor satellite signals according to the following process in order to obtain accurate timing; the following steps are included: The first step is to input the broadcast satellite parameters of the indoor Beidou satellite transmitter. Parameter types include transmitter location coordinates (longitude, latitude, altitude), pseudo-random noise code (PRN number), carrier frequency (such as B1I: 1561.098MHz), signal modulation method (such as BPSK-QPSK), and transmit power (10-30dBm). A mapping relationship between the PRN code and the indoor transmitter is established through a hash table, and dynamic updates are supported (for example, automatically registering new transmitters to the cloud parameter library). The second step is to receive the mixed outdoor and indoor satellite signals. Signal capture: A dual-channel RF front-end (outdoor L1 / L5 bands + indoor B1C band) is used to separate the frequency bands using a bandpass filter (bandwidth 2.046 MHz). For anti-interference processing, narrowband interference (such as Wi-Fi, 2.4 GHz) is injected into the indoor signal, and out-of-band noise is suppressed using an adaptive notch filter. Step 3: Remove the indoor Beidou satellite transmitter signal from the received satellite signal. Correlation peak detection: Generate a local replica based on the indoor transmitter's PRN code. Use a sliding correlator to calculate the signal cross-correlation value and detect indoor signal components with peak values exceeding a threshold (≥0.8). Signal reconstruction and elimination: Utilize the minimum mean square error (MMSE) algorithm to reconstruct the detected indoor signal and subtract the reconstructed component from the mixed signal. The residual signal is the outdoor satellite signal. Dynamic threshold adjustment: Adjust the detection threshold in real time based on the signal-to-noise ratio (SNR) to avoid false alarms and missed detections at low SNRs. Step 4: Obtain and analyze outdoor satellite signals; Navigation message decoding: Extract satellite ephemeris, clock parameters, and ionospheric delay correction, and calculate propagation delay based on the receiver position (assisted by inertial navigation); Multipath mitigation: Use narrow correlation interval technology (Early-Late interval 0.1 chip) to suppress code phase deviation caused by indoor reflections; Step 5: Generate timing and output PPS pulses; Crystal oscillator training: The oven-controlled crystal oscillator (OCXO) is trained through a digital phase-locked loop (DPLL), and the frequency stability after training reaches 1e-11 (Allen variance); Pulse alignment: Based on the UTC time tag (the rising edge of the 1PPS is aligned to the whole second), the Kalman filter is used to compensate for the transmission path delay (±5ns accuracy).

[0023] like Figure 4 As shown in the master-slave base station synchronization timing flow chart, the master-slave base station also has the following clock synchronization process: Step 1: The main transmitter receives outdoor satellite PPS timing. Crystal oscillator training strategy: Phase lock: Compare the phase difference between the satellite PPS and the local crystal oscillator, adjust the DAC output through the PID controller, and control the crystal oscillator voltage-controlled terminal (VCXO). Frequency calibration: Synchronize with the satellite second pulse every 10 minutes to calibrate the crystal oscillator's accumulated error (long-term drift ≤ 0.1ppm). The second step is to use the PPS crystal oscillator training module in the main transmitter to train the crystal oscillator and obtain a stable frequency reference. The modulation method is OFDM (subcarrier spacing of 15kHz), with dual-band redundant transmission at the center frequency of 2.4GHz / 5.8GHz. Timestamp embedding: A precise timestamp is inserted into the frame header (IEEE 1588 PTP protocol), supporting two-way delay compensation. Step 3: The main transmitter uses the trained frequency as a reference, synchronizes the wireless frequency module transmitter, generates a wireless signal and transmits it; Step 4: Receive outdoor satellite PPS timing from the base station to obtain PPS reference; Step 5: The wireless frequency synchronization module receives the wireless frequency synchronization signal from the base station to obtain a frequency reference. Multi-source reference fusion: This module simultaneously receives the satellite PPS and the primary base station wireless signal, using a weighted average algorithm (70% satellite weight + 30% primary base station weight) to generate the final reference. Clock jitter tolerance design: Clock jitter monitoring uses Allan variance to assess local clock stability in real time, triggering dynamic filter coefficient adjustment. Redundancy switchover: If the primary base station signal is lost, the module automatically switches to a backup GNSS receiver module (such as GPS L2C).

[0024] The slave base station performs normal operation based on the acquired PPS reference and frequency reference.

[0025] Example 2: To make the system's indoor positioning more accurate, it is necessary to perform 3D map modeling of multiple indoor locations. This modeling process obtains the indoor signal propagation path and then optimizes the path. Modeling tools: Build a high-precision indoor 3D model (resolution ≤ 10 cm) based on BIM (Building Information Model) and LiDAR point cloud data to obtain a propagation path with lower latency. The first step is to distinguish between O2I (outdoor-to-indoor) and I2I (indoor-to-indoor) scenarios: A corresponding propagation model is constructed for each scenario. For O2I scenarios, the propagation characteristics of outdoor signals penetrating walls into indoor spaces are considered, including factors such as signal attenuation, reflection, and refraction. For I2I scenarios, the propagation characteristics of indoor signals between different rooms and floors are primarily considered. Ray tracing technology is used to simulate the indoor signal propagation path, obtaining measured data such as signal strength, latency, and multipath. Based on the propagation model and measured data, areas with significant indoor multipath effects, such as metal walls and glass partitions, are identified. Signal strength mapping technology is used to identify areas with weak indoor signal strength, known as blind spots. Ray tracing simulation parameters include: maximum number of reflections = 3, diffraction order = 2, and a material property library (20dB attenuation for metal walls and 5dB for glass). Dynamic updates: The model error is inversely corrected (iterative least squares method) using the measured signal strength (RSSI) and time of flight (ToF) at the UWB anchor point.

[0026] The second step is to select unit density based on coverage and frequency. Edge computing units are deployed near the IRS deployment area to process IRS control signals and feedback information in real time. These edge computing units collaborate with a cloud controller via high-speed communication links. The cloud controller is responsible for global IRS management and optimization, formulating a global IRS adjustment strategy based on feedback from each edge computing unit. The edge computing units, in turn, execute specific IRS control operations based on instructions from the cloud controller, achieving collaborative control between the edge and cloud. Real-time channel estimation: The channel impulse response (CIR) is collected every 100ms to extract the RMS delay spread and the number of multipath components. Local decision-making: IRS unit phases are rapidly adjusted based on preset rules (e.g., signal strength > -80dBm), with a response time of ≤10ms. Digital twin mapping: A virtual replica of the indoor environment is constructed, and the IRS configuration policy is trained using reinforcement learning (PPO). Policy delivery: The optimized phase matrix (N×M array) is compressed into differential encoding and pushed to edge nodes via the MQTT protocol.

[0027] Step 3: Intelligent Reflecting Surface (IRS) Configuration and Optimization: The IRS consists of a large number of programmable reflective units, each of which can independently adjust the phase, amplitude, and frequency of the incident signal. Intelligent algorithms are used to optimize the IRS configuration, enabling active control of indoor multipath signals, suppressing multipath interference, and improving positioning accuracy. Specifically, the IRS array layout and unit spacing are designed based on the indoor environment's geometric layout and signal propagation characteristics to ensure effective coverage of the target area. Channel state information (CSI) and location information are used to construct a multipath signal propagation model. Machine learning algorithms are used to predict and optimize IRS configuration parameters, such as phase offset and amplitude attenuation, to achieve maximum coherent signal superposition and minimize interference.

[0028] In addition, the IRS configuration strategy is updated in real time based on changes in the indoor environment and dynamic adjustments to user locations. By monitoring changes in indoor signal strength, identifying the impact of multipath effects and blind spots, and dynamically adjusting the IRS reflection pattern to adapt to positioning requirements in different scenarios.

[0029] Maximize the target user's received signal-to-noise ratio (SNR) and suppress multipath interference. The objective function can be expressed as:

[0030] Among them, Φ is the IRS phase matrix, hd and hr are the direct and reflected channels respectively; hm and k are multipath interference channels; MIMO antenna diversity and IRS beam control are combined to use spatial differential reconstruction to reduce the impact of multipath; collaborative technology for multipath suppression; virtual time reversal mirror (VTRM) technology is used at the receiving end to make the multipath signal energy superimposed in phase and suppress inter-symbol interference (ISI); the polarization direction of the reflected wave is adjusted by IRS to suppress the multipath component of specific polarization; the transmission power is dynamically adjusted according to the multipath intensity to reduce the energy in the interference area, and the IRS array is deployed on the pillars and ceiling. Combined with the edge computing unit, the signal coverage is optimized in real time to achieve a vehicle positioning accuracy of 0.3m.

[0031] In the embodiments disclosed herein, terms such as "installed," "connected," "connected," and "fixed" should be understood broadly. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; and "connected" may refer to a direct connection or an indirect connection via an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments disclosed herein based on specific circumstances.

[0032] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. The pseudo-satellite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings is characterized by: Including indoor Beidou satellite master transmitter, indoor Beidou satellite slave transmitter and vehicle-mounted positioning terminal; The indoor Beidou satellite main transmitter is arranged inside a semi-sheltered factory building, and the semi-sheltered factory building has a metal roof structure, and part of the roof is made of non-metallic materials; The indoor Beidou satellite main transmitter includes a power module, a control module, a wireless frequency synchronization module transmitting end, a satellite PPS timing module, a PPS taming crystal oscillator, a wireless communication module and a pseudo-satellite transmitting module. The power module, PPS taming crystal oscillator, wireless communication module and pseudo-satellite transmitting module are all electrically connected to the control module by signal, and the wireless frequency synchronization module transmitting end and the satellite PPS timing module are all electrically connected to the PPS taming crystal oscillator by signal.

2. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 1, characterized in that: The control module is used to control the power supply module, the wireless frequency synchronization module transmitter, the satellite PPS timing module, the PPS taming crystal oscillator, the wireless communication module and the pseudo-satellite transmitting module; the PPS taming crystal oscillator is used to output a tamed crystal oscillator according to the input PPS pulse; the communication protocol of the wireless communication module is one of the WieWifi and Lora wireless protocols, and the wireless communication module is used for data transmission between base stations.

3. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 1, characterized in that: The power supply module is an ACDC step-down module or a DCDC step-down module, which is used to obtain AC or DC high-voltage current from the power supply cable, and after stepping down the voltage, supply energy to the indoor Beidou satellite transmitter.

4. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 1, characterized in that: The transmitting end of the wireless frequency synchronization module transmits a radio signal of a set frequency based on the PPS disciplined crystal oscillator.

5. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 1, characterized in that: The satellite PPS timing module is used to receive satellite signals and output PPS pulses.

6. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 1, characterized in that: The indoor Beidou satellite slave transmitter includes a power module, a control module, a wireless frequency synchronization module receiving end, a satellite PPS timing module, a wireless communication module, and a pseudo-satellite transmitting module; the wireless frequency synchronization module receiving end is used to receive the frequency signal from the wireless frequency synchronization module transmitting end in the indoor Beidou satellite main transmitter, and at the same time convert the signal into a stable frequency available to the slave transmitter through amplification, frequency division, and filtering.

7. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 6, characterized in that: The vehicle-mounted positioning terminal includes a power module, a satellite receiving module, a computing unit and a 4G / 5G communication module; the satellite receiving module is used to receive satellite signals from outdoor satellites and receive indoor pseudo-satellite signals at the same time.

8. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 6, characterized in that: The operation unit includes a part arranged outdoors and a part arranged indoors; In the outdoor part, the computing unit performs RTK positioning through a 4G / 5G communication module combined with an outdoor RTK differential reference station; In the indoor part, the original observation quantity of indoor pseudo-satellite signal is extracted and combined with the broadcast signal of pseudo-satellite to perform indoor position solution.

9. The pseudolite-based indoor and outdoor integrated positioning system for semi-sheltered factory buildings and vehicles according to claim 7, characterized in that: 4G / 5G communication module enables wireless communication of vehicle-mounted equipment.

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