An adaptive projection navigation method and system for outdoor navigation

Abstract

The application provides an adaptive projection navigation method and system for outdoor navigation, comprising: generating master navigation instructions and slave navigation instructions through a master device terminal, converting the slave navigation instructions into low-frequency flicker coding; generating a master navigation identifier, and forming a projection navigation identifier with low-frequency flicker coding after superimposing the low-frequency flicker coding on the master navigation identifier; decoding the slave navigation instructions through a slave projection module; generating a slave navigation identifier through the slave projection module, and projecting the slave navigation identifier to the ground in front of a carrier of the slave navigation terminal. The application realizes lightweight group cooperation of multiple intelligent terminals in an outdoor navigation scene by means of a master-slave role differentiation configuration, a dedicated communication link construction mechanism, and a projection pattern low-frequency coding superposition and photosensitive passive decoding cooperation strategy, and significantly reduces the energy consumption and hardware complexity of multiple device cooperation under the premise of ensuring navigation synchronization accuracy.

Description

Technical Field

[0001] This application relates to the field of smart terminals, and more specifically, to an adaptive projection navigation method and system for outdoor navigation. Background Technology

[0002] With the increasing popularity of outdoor activities such as hiking, mountaineering, and field exploration, the demand for safety and collaboration in outdoor navigation is rising. In outdoor group navigation scenarios, existing solutions mostly rely on networking technologies such as Bluetooth Mesh and Wi-Fi to achieve multi-terminal information exchange.

[0003] Such multi-terminal information interaction solutions have many drawbacks. For example, networking technology requires each terminal to maintain a continuous communication connection, resulting in extremely high power consumption, which significantly shortens the battery life of outdoor equipment and makes it difficult to adapt to long-term outdoor activities. Furthermore, in outdoor environments without mobile networks, with signal blockage, or with terrain obstruction, networking is prone to disconnection and delay, leading to asynchronous navigation information and causing problems such as team dispersal and deviation from the route. Summary of the Invention

[0004] To address the problems existing in current technologies, this application provides an adaptive projection navigation method and system for outdoor navigation. The specific solution is as follows:

[0005] An adaptive projection navigation method for outdoor navigation, comprising:

[0006] Configure the smart terminal cluster with master and slave roles to determine the master device terminal and slave device terminal, and establish communication links between the master device terminal and the master projection module, and between the slave device terminal and the slave projection module respectively;

[0007] The main device terminal generates main navigation commands and secondary navigation commands based on navigation data, converts the secondary navigation commands into low-frequency flashing codes, and transmits the main navigation commands and low-frequency flashing codes together to the main projection module.

[0008] The main projection module generates a main navigation identifier for the main navigation terminal carrier based on the main navigation command, and projects the low-frequency flashing code onto the ground in front of the main navigation terminal carrier after superimposing the low-frequency flashing code into the main navigation identifier, thus forming a projected navigation identifier with the low-frequency flashing code.

[0009] The projection module captures the projected navigation markers on the ground and decodes the navigation instructions from them using the built-in photosensitive decoding module, and then transmits the navigation instructions to the slave device terminal.

[0010] The projection module generates a navigation identifier for the user of the navigation terminal based on the navigation instructions, and projects the navigation identifier onto the ground in front of the user of the navigation terminal.

[0011] In some specific embodiments, a binary encoding rule is used to convert navigation commands into low-frequency flashing codes. The frequency of the low-frequency flashing codes is 0.1Hz and the number of encoding bits is 4-8. The main navigation commands and the low-frequency flashing codes are encapsulated into a unified data frame. The header of the data frame is the command type identifier and the tail is the check code. The data frame is transmitted to the main projection module through the established low-power Bluetooth link.

[0012] In some specific embodiments, the main projection module has a built-in encoding driver module. After receiving the main navigation command, the encoding driver module calls a preset sign template to generate a main navigation sign. The main navigation sign is arrow-shaped and marked with the distance to the next node and a road condition warning icon. The encoding driver module superimposes the low-frequency flashing code into the brightness adjustment link of the main navigation sign to realize synchronous low-frequency flashing during the projection process of the main navigation sign.

[0013] In some specific embodiments, the photosensitive decoding module of the projection module is arranged coaxially with the projection lens, and the sensing range of the photosensitive decoding module matches the projection range of the projection lens in order to capture low-frequency flickering signals in the projected navigation sign.

[0014] In some specific embodiments, the photosensitive decoding module first filters the captured flashing signal, and then decodes the navigation command based on a preset binary encoding rule;

[0015] After decoding, the projection module transmits the decoded navigation command to the corresponding slave device terminal via a Bluetooth Low Energy link. During the transmission, decoding verification information is carried. If the slave device terminal determines that the verification has failed, it will send a message back to the projection module to re-decode.

[0016] If the photosensitive decoding module fails to capture a low-frequency flashing signal that meets the requirements for 5 consecutive seconds, or fails to decode and verify 3 times in a row, a disconnection warning signal will be triggered and transmitted to the slave device terminal.

[0017] In some specific embodiments, both the main projection module and the secondary projection module are integrated into the head or chest of the corresponding terminal wearer;

[0018] When worn on the head, the projection angle is downwards at 20°-30°, and the projection distance is 1.5-3m.

[0019] When worn on the chest, the projection angle is downwards at 15°-25°, and the projection distance is 1-2m.

[0020] In some specific embodiments, it also includes:

[0021] By capturing the cadence signal of the corresponding terminal wearer through a preset cadence sensor, the projection brightness is continuously increased at the vibration peak of the cadence signal, decreased at the vibration trough of the cadence signal, and decreased in the static state and switched to a breathing flashing mode.

[0022] In some specific embodiments, the primary navigation identifier includes the direction of travel, distance information, and traffic warning information; the secondary navigation identifier includes at least the direction of travel.

[0023] In some specific embodiments, the method further includes: collecting user motion characteristics and ambient brightness characteristics; adjusting the brightness parameters of the projected sign based on the motion characteristics; determining whether the projected area is covered by human shadows based on the ambient brightness characteristics; and if it is determined to be covered by shadows, triggering local supplemental lighting and switching the color parameters of the projected sign.

[0024] An adaptive projection navigation system for outdoor navigation, comprising:

[0025] The terminal partitioning unit is used to configure the master and slave roles of the smart terminal cluster to determine the master device terminal and the slave device terminal, and to establish communication links between the master device terminal and the master projection module, and between the slave device terminal and the slave projection module, respectively.

[0026] The main navigation unit is used to generate main navigation instructions and secondary navigation instructions based on navigation data through the main device terminal, convert the secondary navigation instructions into low-frequency flashing codes, and transmit the main navigation instructions and the low-frequency flashing codes together to the main projection module.

[0027] The main projection unit is used to generate a main navigation identifier for the main navigation terminal carrier based on the main navigation command through the main projection module, and project the low-frequency flashing code onto the ground in front of the main navigation terminal carrier after superimposing the low-frequency flashing code into the main navigation identifier, forming a projected navigation identifier with the low-frequency flashing code.

[0028] The navigation unit is used to capture the projected navigation marks on the ground through the photosensitive decoding module built into the projection module and decode the navigation instructions from them, and transmit the navigation instructions to the slave device terminal;

[0029] The projection unit is used to generate a navigation identifier for the carrier of the navigation terminal based on the navigation instruction through the projection module, and to project the navigation identifier onto the ground in front of the carrier of the navigation terminal.

[0030] Beneficial Effects: This application proposes an adaptive projection navigation method and system for outdoor navigation. By differentiating the master and slave roles and constructing a dedicated communication link, combined with a low-frequency encoding superposition of projection patterns and a photosensitive passive decoding collaborative strategy, it achieves lightweight group collaboration of multiple intelligent terminals in outdoor navigation scenarios. This enables navigation command synchronization and projection mark interaction between master and slave devices to be achieved without relying on complex network communication. Core navigation information can be transmitted solely through ground projection encoding. Furthermore, by using differentiated generation logic for master and slave navigation marks and a decoding validity determination mechanism, the system significantly reduces the energy consumption and hardware complexity of multi-device collaboration, extends outdoor battery life, and effectively improves the stability and adaptability of multi-terminal group navigation in complex outdoor environments with no signal, while ensuring the navigation synchronization accuracy and visibility of navigation information between master and slave devices.

[0031] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the adaptive projection navigation method for outdoor navigation according to this application;

[0034] Figure 2 This is a schematic diagram illustrating the principle of the adaptive projection navigation method of this application;

[0035] Figure 3 This is a flowchart illustrating the coding-driven process of this application;

[0036] Figure 4 This is a schematic diagram of the process of obtaining navigation instructions in this application;

[0037] Figure 5 This is a schematic diagram of the adaptive projection navigation system module for outdoor navigation according to this application.

[0038] Reference numerals in the attached figures: 1-Terminal division unit; 2-Main navigation unit; 3-Main projection unit; 4-Slave navigation unit; 5-Slave projection unit. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0040] This application proposes an adaptive projection navigation method for outdoor navigation. Through directional collaborative linkage between multiple smart terminals and corresponding projection modules, it significantly avoids the high power consumption and disconnection risks of traditional network-based navigation while ensuring the continuity of group navigation and the accuracy of sign recognition. This effectively improves the stability, portability, and battery life of multi-device group navigation in complex outdoor signal-free environments. A flowchart of the adaptive projection navigation method is attached. Figure 1 As shown in the attached diagram, the principle is as follows: Figure 2 As shown, the specific solution is as follows:

[0041] An adaptive projection navigation method for outdoor navigation, comprising:

[0042] 101. Configure the master and slave roles of the smart terminal cluster to determine the master device terminal and the slave device terminal, and establish communication links between the master device terminal and the master projection module, and between the slave device terminal and the slave projection module respectively;

[0043] 102. The main device terminal generates main navigation commands and secondary navigation commands based on navigation data, converts the secondary navigation commands into low-frequency flashing codes, and transmits the main navigation commands and low-frequency flashing codes together to the main projection module.

[0044] 103. The main projection module generates a main navigation mark for the main navigation terminal carrier based on the main navigation command, and then projects a low-frequency flashing code onto the ground in front of the main navigation terminal carrier after superimposing a low-frequency flashing code on the main navigation mark, forming a projected navigation mark with a low-frequency flashing code.

[0045] 104. By capturing the projected navigation marks on the ground from the photosensitive decoding module built into the projection module and decoding the navigation commands from them, the navigation commands are transmitted to the slave device terminal.

[0046] 105. Generate a navigation sign for the user of the navigation terminal based on the navigation instructions from the projection module, and project the navigation sign onto the ground in front of the user of the navigation terminal.

[0047] The core objective of step 101 is to complete the basic architecture for multi-device collaborative navigation. This is achieved by first dividing the cluster containing multiple smart terminals into master and slave roles. This division can be achieved in two core ways: one is based on user-initiated operation, where the user designates a smart terminal in the cluster as the master terminal, and the remaining terminals are automatically matched as slave terminals; the other is based on the real-time location distribution characteristics of each terminal in the cluster to automatically complete the division, ensuring that the master terminal is in a core position that facilitates the transmission of navigation information to all slave terminals.

[0048] After the master and slave roles are determined, independent communication connections are established between the master device terminal and the dedicated master projection module, and between each slave device terminal and its corresponding slave projection module. The establishment of these communication connections is the basis for subsequent navigation commands and related data transmission.

[0049] The communication links between the master and slave devices and their corresponding projection modules are independent, avoiding signal interference between different devices. Through clear master-slave role definition and the construction of dedicated communication links, architectural support is provided for the centralized generation and distributed synchronous transmission of subsequent navigation information. This enables an orderly division of labor in multi-device collaborative navigation, ensuring that subsequent operations proceed smoothly according to master-slave logic.

[0050] Step 102 is the core link in the entire collaborative navigation data processing and transmission. Its core purpose is to generate differentiated navigation instructions and complete the special encoding conversion from navigation instructions to achieve efficient transmission of navigation information.

[0051] First, the main device acquires the basic navigation data required for outdoor navigation. This data comes from the device's built-in positioning module and pre-loaded map data. The main device then analyzes and processes this data, generating primary navigation commands and secondary navigation commands. The primary navigation commands contain complete navigation information to meet the user's need for detailed navigation information, while the secondary navigation commands focus on core navigation direction information to simplify subsequent transmission and decoding processes.

[0052] Subsequently, the main device terminal converts the generated navigation commands into low-frequency flashing codes. This encoding conversion process must follow preset encoding rules to ensure that the encoded information can accurately map the core content of the navigation commands, while ensuring that the low-frequency characteristics of the encoding meet the requirements of the human eye's visual perception range.

[0053] Finally, the main device terminal integrates and encapsulates the main navigation command with the converted low-frequency flashing code to form a standardized data transmission unit and transmits it to the main projection module.

[0054] Differentiated commands are generated based on the different navigation needs of master and slave devices. Low-frequency flashing encoding is used to encrypt and transform the slave navigation commands, ensuring both the uniqueness and identifiability of the slave navigation information and avoiding interference with the transmission of master navigation commands. Its key features lie in the differentiated generation of commands and the exclusive adaptability of the encoding. The ultimate effect is to achieve the classification, processing, and efficient transmission preparation of navigation information, providing accurate data support for the subsequent projection output of the master projection module.

[0055] The core objective of step 103 is to visualize the main navigation information and overlay it with the secondary navigation encoded signal, thereby achieving dual output of navigation information.

[0056] The main projection module receives the main navigation command and low-frequency flashing code transmitted by the main device terminal. Based on the main navigation command, it calls the built-in navigation identifier generation rules to generate a main navigation identifier that matches the navigation needs of the main device terminal user. This identifier must have clear navigation guidance attributes and be able to intuitively reflect core navigation information such as the direction of travel.

[0057] The main projection module uses a built-in encoding overlay module to overlay low-frequency flicker codes onto the generated main navigation sign. The overlay process must ensure that the low-frequency flicker codes can be stably integrated with the main navigation sign without affecting the normal visual recognition effect of the main navigation sign, while ensuring the integrity and detectability of the encoded signal.

[0058] The main projection module projects the main navigation mark, which is superimposed with low-frequency flashing code, onto the ground area in front of the user of the main device terminal through the built-in projection unit. During the projection process, the projection angle and range need to be adjusted according to the preset projection parameters to ensure that the projected navigation mark can accurately cover the normal field of vision of the user of the main device terminal.

[0059] By utilizing projection visualization technology, navigation instructions are transformed into directly observable markers. Through encoding overlay, a single projection carrier can carry dual navigation information, fully leveraging the intuitiveness and wide coverage of ground projection. Its key features lie in the navigation adaptability of the projected markers and the compatibility of the encoding overlay. The ultimate effect is that the user of the main device terminal can clearly obtain complete navigation information, while simultaneously providing a captureable signal carrier for the navigation synchronization of the slave device terminal.

[0060] The core objective of step 104 is to achieve passive synchronous acquisition of navigation information from the main device from the device terminal, thereby completing the accurate parsing of navigation commands.

[0061] The projection module continuously captures projection information of the ground area ahead via its built-in photosensitive decoding module. This module possesses high sensitivity for capturing low-frequency light signals, enabling it to accurately identify the low-frequency flickering coded signals superimposed on the ground-projected navigation markings. After capturing the target signal, the photosensitive decoding module filters the signal, removing interference signals such as ambient light and retaining the pure low-frequency flickering coded signal. Then, based on preset decoding rules, it parses the coded signal to reconstruct the corresponding navigation commands. After parsing, the projection module transmits the decoded navigation commands to the corresponding slave device terminal, completing the transmission of navigation information.

[0062] By leveraging the light-sensing characteristics of photosensitive sensors, passive capture and parsing of coded signals superimposed on projected markers can be achieved without establishing a direct communication link between master and slave devices, thus reducing the complexity of cooperative navigation. Its key features lie in the high efficiency of passive capture and the accuracy of decoding. The ultimate effect is that slave devices can synchronously acquire core navigation information from the master device without relying on an additional communication link, providing data for the subsequent generation of navigation markers.

[0063] The core objective of step 105 is to visualize the parsed navigation information, thereby enabling precise navigation guidance for users of the device terminal.

[0064] The system receives navigation information confirmation signals from the device terminal via the projection module. Based on the decoded navigation instructions, it calls the built-in simplified navigation identifier generation rules to generate a navigation identifier that is adapted to the needs of the device terminal user. This identifier focuses on the core direction of travel information, ensuring that it is simple, clear and easy to identify.

[0065] The projection module adjusts projection parameters, including projection angle, projection range, and projection brightness, based on its wearing position and outdoor environment. This ensures that navigation signs are accurately projected onto the ground area in front of the user, and that the projection effect is adapted to the current lighting conditions and ground environment. Finally, a stable projection of the navigation signs is achieved, allowing the user to intuitively obtain navigation guidance information.

[0066] Based on the simplified navigation needs of the device terminal, targeted navigation signs are generated, and the visibility and accuracy of the signs are ensured through dynamic adaptation of projection parameters. Its key features are the simplification of the signs and the adaptability of the projection. The ultimate effect is to provide clear navigation guidance to the device terminal wearer, complete the closed loop of the entire master-slave device collaborative projection navigation, and ensure the navigation consistency of all members in outdoor group navigation.

[0067] This application uses Bluetooth Low Energy to achieve point-to-point communication between the terminal and the corresponding module. The core hardware focuses on the encoding and overlay unit of the main projection module and the photosensitive decoding unit of the slave projection module. Other auxiliary modules are integrated as needed and reuse hardware resources.

[0068] The smart terminal hardware only needs to be equipped with a standard positioning module and a low-power Bluetooth module, responsible for navigation data generation, master-slave role configuration, and encoding command conversion, without requiring an additional communication chip. The core hardware of the main projection module includes an encoding driver module, a high-brightness micro LED light source, and a fixed-focus optical lens. The encoding driver module uses an MCU to receive the main navigation command and low-frequency flashing encoding command transmitted from the terminal, and then precisely controls the brightness and flashing frequency of the LED light source through a PWM signal. The core hardware of the slave projection module is a photosensitive decoding module, which consists of a high-sensitivity silicon photodiode, a filter amplification circuit, and a decoding chip. The silicon photodiode captures the low-frequency flashing signal of the ground projection, and the filter circuit removes ambient light interference, focusing on filtering out noise signals beyond 0.1Hz. The decoding chip parses the team number and navigation direction based on preset binary rules, and then feeds it back to the slave device terminal via low-power Bluetooth. At the same time, the slave projection module reuses the LED light source and fixed-focus lens of the main module to generate only a simplified navigation mark.

[0069] In terms of auxiliary hardware, a piezoelectric ceramic vibration sensor is selected as the step frequency sensor. It is integrated inside the module housing and connects to the module MCU via an I2C interface to transmit step frequency signals in real time to adjust the brightness of the light source. An ambient light sensor is connected in series with a miniature supplementary LED on the edge of the module. When a shadow area is detected, supplementary lighting is triggered. The optical path of the supplementary LED is coaxial with the optical path of the projection lens, so it does not affect the projection and recognition of the encoded signal. The power module uses a small lithium polymer battery and supports low-power mode switching. When the module does not recognize the code, it automatically reduces the power consumption of the decoding module to further extend the battery life.

[0070] In some specific embodiments, a binary encoding rule is used to convert navigation commands into low-frequency flashing codes. The low-frequency flashing code has a frequency of 0.1Hz and a bit length of 4-8 bits. The main navigation commands and the low-frequency flashing code are encapsulated into a unified data frame. The data frame header contains a command type identifier, and the tail contains a checksum. This frame is then transmitted to the main projection module via an established Bluetooth Low Energy link. The encoding process is shown in the attached figure. Figure 3 As shown.

[0071] The binary encoding rule uses bit allocation mapping logic. Bit resources for 4-8 bit encoding are divided according to function: for example, in 4-bit encoding, the high 2 bits are used to represent the team number (covering 4 teams from 00 to 11), and the low 2 bits are used to represent the direction of travel (00 = straight, 01 = left turn, 10 = right turn, 11 = stay). For 8-bit encoding, the high 4 bits can be expanded to represent the team number (covering 16 teams from 0000 to 1111), the low 3 bits to represent the direction of travel, and the remaining 1 bit is used as a check bit to further improve decoding accuracy. The 0.1Hz frequency of the low-frequency flashing encoding is precisely controlled by a timer on the main device terminal, completing a full encoding cycle every 10 seconds. For example, 1 corresponds to one flash, and 0 corresponds to no flashing. The duration of a single bit is 1.25-2.5 seconds, matching the signal capture duration of the decoding module.

[0072] The data frame encapsulation adopts a fixed format, with a total length controlled within 16 bytes to adapt to the low-bandwidth transmission requirements of Bluetooth Low Energy. The header instruction type identifier occupies 1 byte, with a preset value of 0x01, which is used by the main projection module to quickly identify the instruction type and trigger the corresponding processing flow; the middle data segment is divided into two parts: the main navigation instruction occupies 4-8 bytes, storing information such as the direction of travel and the distance to the next node, and the low-frequency flashing code occupies 1 byte; the tail check code occupies 1 byte, which uses an XOR check algorithm to calculate the XOR value of the header and the middle data segment. After receiving it, the main projection module checks it using the same algorithm. If the check fails, it requests a retransmission from the main device terminal.

[0073] The transmission process uses a BLE 5.0 low-power Bluetooth module with a communication baud rate of 115200bps and a transmission interval of 500ms to ensure real-time command transmission and low power consumption, while avoiding signal interference between multiple devices.

[0074] In some specific embodiments, the main projection module has a built-in encoding driver module. After receiving the main navigation command, the encoding driver module calls a preset sign template to generate a main navigation sign. The main navigation sign is arrow-shaped and marked with the distance to the next node and a road condition warning icon. The encoding driver module superimposes low-frequency flashing encoding onto the brightness adjustment link of the main navigation sign, realizing synchronous low-frequency flashing during the projection process of the main navigation sign. The superposition process does not change the original shape and core information of the main navigation sign. The encoding driver process is shown in the appendix. Figure 3 As shown.

[0075] The main projection module's built-in encoding driver module constructs an integrated link for instruction parsing, identifier generation, encoding overlay, and projection output. The core logic is to limit the overlay of low-frequency flickering encoding to the brightness adjustment dimension of the main navigation identifier, rather than the graphic dimension. In this way, without changing the original shape and core information of the main navigation identifier, it achieves the dual goals of visual navigation information transmission and non-visual encoding synchronization. This provides a stable signal source for subsequent passive decoding by slave devices while ensuring that the main navigation terminal user can clearly identify the navigation information.

[0076] After receiving the unified data frame transmitted from the master device terminal, the encoding driver module first separates the main navigation command and low-frequency flashing code through its built-in command parsing unit. The main navigation command is parsed to extract key information such as travel direction, distance to the next node, and road condition warning type. Then, it calls the identifier template library pre-stored in the module's flash memory. This library contains various arrow shape templates to match the visibility requirements at different projection distances, and also includes distance number annotation templates and road condition warning icon templates. Based on the parsed information, the encoding driver module calls the corresponding template and uses a pixel overlay algorithm to fuse the arrow shape, distance annotations, and warning icons to generate a complete main navigation identifier pixel matrix. Preferably, the resolution is preset to 800×600 to adapt to the projection clarity of a fixed-focus lens. The simple arrow shape and standardized annotations and icons adapt to the visibility requirements in complex outdoor lighting environments, while the brightness overlay method of low-frequency encoding, compared to graphic overlay, is more resistant to interference from ground textures and debris on the encoded signal, ensuring the stability of master-slave device collaborative navigation.

[0077] For the overlay of low-frequency flicker codes, the encoding drive module achieves this by controlling the PWM dimming unit in the brightness adjustment link. First, the binary low-frequency flicker code is converted into a corresponding brightness control timing signal. That is, "1" in the code corresponds to a high duty cycle brightness signal output by the PWM dimming unit, and "0" corresponds to a low duty cycle brightness signal. The timing of this brightness change is strictly synchronized with the encoding frequency. Subsequently, this brightness control timing signal is overlaid into the overall brightness drive link of the main navigation sign, so that the main navigation sign synchronously completes low-frequency brightness fluctuations during projection. Because the brightness fluctuation amplitude is controlled within the human eye's visual threshold, the human eye cannot perceive the fluctuations and can only clearly see the complete arrows, distance markings, and warning icons. Finally, the encoding drive module transmits the pixel signal of the main navigation sign with the overlaid brightness code to the projection light source drive unit, which controls the high-brightness micro LED light source to project onto the ground in front through a fixed-focus lens, forming a stable projection navigation sign with low-frequency flicker codes.

[0078] This embodiment ensures the compatibility of information transmission, ensuring that the main navigation terminal user can quickly obtain core navigation information such as direction of travel, distance, and road conditions, while providing a stable and interference-resistant low-frequency flicker signal source for the photosensitive decoding module of the slave device. Furthermore, it eliminates the need for additional independent light sources or projection channels for encoding overlay, achieving encoding overlay through brightness adjustment link multiplexing, thus reducing module size and power consumption.

[0079] In some specific embodiments, the photosensitive decoding module of the projection module is coaxially arranged with the projection lens, and the sensing range of the photosensitive decoding module matches the projection range of the projection lens to capture low-frequency flickering signals in the projected navigation signs. The photosensitive decoding module and the projection lens are fixed on the same optical axis, with the distance between them controlled at 8-12mm, and both are embedded in the metal limiting seat at the front end of the module. The limiting seat is locked to the module body by a threaded structure to ensure that the optical axis deviation between the two does not exceed ±0.5° after assembly, avoiding the photosensitive module missing the flickering signal of the projected navigation signs due to axis misalignment.

[0080] The projection lens uses optical lenses with corresponding field of view angles based on the wearing scenario. The field of view angle of the projection lens is set to 30°-40° for head-wearing scenarios and 25°-35° for chest-wearing scenarios. Correspondingly, a light shield with the same field of view angle is installed at the front end of the photosensitive decoding module. The aperture of the light shield is 6-8mm. By limiting the sensing range of the photosensitive module, its effective sensing area completely overlaps with the projection area of ​​the projected navigation mark, while reducing interference from ambient light.

[0081] To improve the reliability of low-frequency flicker signal capture, the photosensitive decoding module also integrates a signal preprocessing circuit: first, a 20Hz low-pass filter removes high-frequency ambient light interference, and then a comparator converts the analog light signal into a digital level signal. Specifically, a high level (corresponding to code '1') is output when the flicker intensity is ≥50 lux, and a low level (corresponding to code '0') is output when the intensity is <10 lux, matching the brightness change logic of the low-frequency flicker code. Furthermore, the module has a built-in timing synchronization unit that calibrates the sampling frequency using a crystal oscillator (accuracy ±1ppm) to ensure that the sampling period for the 0.1Hz low-frequency signal is precisely controlled at 10ms / time, avoiding missed or misreading of the code due to sampling timing deviations.

[0082] The 0.1Hz low-frequency flicker signal is characterized by its long period, gradual changes, and stable brightness, exhibiting a significant frequency difference from ambient noise in the outdoor environment. This frequency difference provides a natural basis for signal separation. The energy of the low-frequency signal is concentrated in the low-frequency band, while ambient noise is mostly distributed in the mid-to-high frequency band. Effective separation of the two can be achieved through targeted filtering design, laying the foundation for signal-level feasibility for accurate extraction.

[0083] The photosensitive elements with low dark current and high responsivity, such as BPW34 silicon photovoltaic cells and S1133 photodiodes, are selected. Their spectral response range matches the emission band of the projected navigation sign, and the detection threshold for weak light signals can be as low as 10 lux. They can accurately capture the changes in brightness during low-frequency flickering and can distinguish the difference between flickering light and ambient background light even in low-light outdoor environments.

[0084] By using a design that places the photosensitive decoding module and the projection lens coaxially and uses a light shield of the same field of view, the effective sensing range of the photosensitive module completely overlaps with the projection area of ​​the projected navigation sign, avoiding signal loss due to sensing range offset; at the same time, the light shield can block direct illumination from ambient stray light, reducing interference from ambient light on signal detection.

[0085] In some specific embodiments, the photosensitive decoding module first filters the captured flickering signal, and then decodes the navigation command based on a preset binary encoding rule. After decoding, the projection module transmits the decoded navigation command to the corresponding slave device terminal via a low-power Bluetooth link. During the transmission, decoding verification information is carried. If the slave device terminal determines that the verification has failed, it will feed back to the projection module to re-decode. If the photosensitive decoding module fails to capture a low-frequency flickering signal that meets the requirements for 5 consecutive seconds, or fails the decoding verification 3 times in a row, it will trigger a departure warning signal and transmit it to the slave device terminal.

[0086] After the photosensitive decoding module captures the low-frequency flickering signal of the ground-projected navigation marker, it first filters the original signal through a built-in 20Hz low-pass filter. This filter can accurately filter out mid-to-high frequency interference noise above 1Hz in the outdoor environment, such as high-frequency fluctuations from direct sunlight, random flickering of leaf shadows, and high-frequency flickering from surrounding light sources, retaining only the target low-frequency flickering signal of about 0.1Hz. Simultaneously, the low-noise operational amplifier within the module amplifies the weak μA-level analog electrical signal output from the photosensitive element to a processable mV-level signal. Then, a voltage comparator performs a digital threshold determination, outputting a high level for light intensity ≥50 lux and a low level for light intensity <10 lux, converting the filtered and amplified analog signal into a digital level signal that perfectly matches the binary encoding logic. Based on the pre-stored binary encoding bit allocation rules, the digital level signal sequence is parsed bit by bit, ultimately decoding to obtain the navigation instructions containing team affiliation and movement commands. The process is attached. Figure 4 As shown.

[0087] After decoding, the projection module encapsulates the decoded navigation instructions and corresponding verification information into a fixed-length data frame, and transmits it to the corresponding slave device terminal through a preset BLE5.0 low-power Bluetooth link at a baud rate of 115200bps and a transmission interval of 500ms.

[0088] Preferably, after receiving a data frame from the device terminal, the validity of the instruction content is verified according to the same verification algorithm. If the verification fails, a re-decoding instruction is immediately sent back to the projection module, triggering the photosensitive decoding module to recapture the signal and execute the filtering and decoding process.

[0089] Throughout the decoding and transmission process, the projection module monitors the effective signal capture status and the number of verification failures in real time through its built-in timer. If the photosensitive decoding module fails to capture a low-frequency flashing signal that meets the frequency and amplitude requirements for 5 consecutive seconds, or if the decoding verification fails 3 times in a row, it will automatically generate a departure warning signal. This signal will be transmitted synchronously to the slave device terminal. After receiving the signal, the slave device terminal can trigger an audio-visual prompt. At the same time, the projection module can switch to independent navigation mode and generate a temporary navigation marker based on its own stored basic navigation data to ensure the navigation continuity for the user of the navigation terminal.

[0090] In some specific embodiments, both the main projection module and the secondary projection module are integrated into the head or chest of the corresponding terminal wearer; when worn on the head, the projection angle is 20°-30° downward and the projection distance is 1.5-3m; when worn on the chest, the projection angle is 15°-25° downward and the projection distance is 1-2m.

[0091] Both the main projection module and the secondary projection module adopt a lightweight wearable design, which can be directly integrated into the head-wearing device or chest-wearing carrier of the terminal wearer, taking into account both portability and stability in outdoor mobile scenarios.

[0092] When worn on the head, the module is fixed by an adjustable bracket with a precisely set downward angle of 20°-30° and a projection distance of 1.5-3m. The design of this angle and distance parameters avoids direct light from the projected light into the eyes of the wearer or teammates, thus preventing visual interference, while ensuring that the projected navigation mark falls clearly in the effective area of ​​the ground directly in front of the wearer. Moreover, this projection distance perfectly matches the optimal sensing range of 1-3m from the photosensitive decoding module of the projection module, ensuring stable capture of low-frequency flickering encoded signals.

[0093] When worn on the chest, the module is embedded in the reserved slot of the chest carrier. The projection angle is adjusted to 15°-25° downward, and the projection distance is shortened to 1-2m. Since the height of the chest is lower than the head, the slightly smaller downward tilt angle can prevent the pattern from being distorted due to the projected sign being too close to the feet. At the same time, the short projection distance of 1-2m is more suitable for the scenario of dense formation of small teams, which can effectively avoid the overlap and confusion of projected signs from multiple terminals. Moreover, this distance is also within the effective sensing range of the photosensitive decoding module.

[0094] In addition, both types of modules are equipped with an angle fine-tuning knob, which can flexibly adjust the projection parameters according to the wearer's height, stride and outdoor terrain, further improving the projection adaptability and decoding accuracy in complex environments.

[0095] In some specific embodiments, the method further includes: capturing the gait frequency signal of the corresponding terminal carrier using a preset gait frequency sensor; continuously increasing the projection brightness during the vibration peak of the gait frequency signal; decreasing the projection brightness during the vibration trough of the gait frequency signal; and decreasing the projection brightness and switching to a breathing flashing mode when stationary. Both the main projection module and the slave projection module integrate a miniature three-axis accelerometer gait frequency sensor. This sensor is linked to the projection brightness driving circuit to dynamically adjust the projection brightness by capturing the gait frequency vibration signal of the terminal carrier during walking in real time.

[0096] The cadence sensor monitors the acceleration changes of the wearer during strides at a sampling frequency of 100Hz. When the detected acceleration value exceeds a preset threshold, it is determined to be a peak cadence vibration, corresponding to the stage where the wearer exerts force during strides. At this time, the drive circuit automatically increases the duty cycle of the LED light source PWM (Pulse Width Modulation) of the projection module, increasing the projection brightness from the base value to 80%-90%, ensuring that the ground navigation marks remain clearly identifiable even when the wearer is moving quickly, adapting to the visual tracking needs of the squad during movement. When the detected acceleration value is below a preset threshold (e.g., 0.2g), it is determined to be... The trough of the step frequency vibration corresponds to the stage when the carrier steps back. The drive circuit synchronously reduces the PWM duty cycle, reducing the brightness to 40%-50% to reduce energy consumption while meeting basic recognition requirements. If the sensor does not detect an effective acceleration change for 3 consecutive seconds, it is determined that the carrier is in a stationary state. At this time, the drive circuit further reduces the brightness to 20%-30% and controls the projection light source to switch to a breathing flashing mode with a frequency of 1Hz. This avoids the energy waste and glare caused by continuous high brightness when stationary, and the flashing effect helps teammates quickly locate the carrier's position.

[0097] In addition, the cadence sensor supports adaptive threshold calibration, which can automatically adjust the peak and valley value judgment parameters according to the stride size and walking speed of different users, adapting to different walking states such as fast walking and slow walking. At the same time, this adjustment mechanism is linked with the transmission interval of the low-power Bluetooth communication link, synchronously extending the data transmission interval in the stationary state, further improving the overall battery life of the device.

[0098] In some specific embodiments, the primary navigation identifier includes the direction of travel, distance information, and road condition warnings; the secondary navigation identifier includes at least the direction of travel. This differentiated design of primary and secondary navigation identifiers ensures both the comprehensiveness and accuracy of navigation guidance, while also optimizing energy consumption by simplifying the secondary identifier information, further improving the efficiency and stability of multi-terminal collaborative navigation.

[0099] The main navigation marker, serving as the core guide for the team's navigation, presents multi-dimensional navigation information using a clear combination of graphics and text. The direction of travel is clearly marked by a highlighted arrow, with the arrow's direction precisely corresponding to the actual direction of travel. It also utilizes red, green, and blue colors to enhance visual recognition and adapt to various lighting conditions, including strong and low light. Distance information is displayed as numbers and units superimposed next to the direction arrow, accurately showing the distance between the current location and the next navigation node. This distance value updates in real-time as the user moves. Road condition warnings are presented using specific icons and brief text prompts, covering common complex outdoor road conditions such as obstacles, steep slopes, and forks in the road. For example, a triangular exclamation mark icon is used with the text "50-meter steep slope ahead." The warning icon uses a highly saturated yellow to ensure rapid detection in complex terrain, providing the team with a basis for safe prediction.

[0100] The secondary navigation sign focuses on core guidance needs, retaining only the direction of travel information. Its presentation format is consistent with the directional arrows of the main navigation sign, but its size is reduced by 30% compared to the main navigation sign. This reduces projection energy consumption, avoids confusion with the main navigation sign, and ensures that the device holder can quickly capture key directional information, adapting to the collaborative mode of "main device coordination and secondary device following" in squad formation.

[0101] In some specific embodiments, the method further includes: collecting user motion characteristics and ambient brightness characteristics; adjusting the brightness parameters of the projected sign based on the motion characteristics; determining whether the projected area is covered by human shadows based on the ambient brightness characteristics; and if it is determined to be covered by shadows, triggering local supplemental lighting and switching the color parameters of the projected sign.

[0102] Both the main projection module and the slave projection module integrate a three-axis accelerometer and an ambient light sensor, constructing a motion-environment dual-feature acquisition link to achieve dynamic adaptive optimization of the projected signage. Motion feature acquisition covers three core parameters: stride frequency, walking speed, and gait amplitude. Brightness adjustment logic is deeply integrated with the motion state. When a fast-moving state is detected, the drive circuit increases the PWM duty cycle to 85%-95%, maximizing projection brightness to meet the visual tracking requirements under high-speed movement. When a slow-moving or meandering state is detected, the brightness is reduced to 40%-50%, ensuring legibility while reducing energy consumption.

[0103] The ambient light sensor focuses on collecting local light intensity in the projection area. It determines whether there is human shadow coverage by comparing the difference between the overall ambient brightness and the measured brightness of the projection area. The preset judgment threshold is that the brightness of the projection area is less than 30% of the overall ambient brightness and the duration is greater than 1 second. This threshold can be automatically calibrated according to the outdoor scene to avoid misjudgment due to sudden changes in light.

[0104] Once it is determined that the projection area is covered by a human shadow, the module immediately triggers a dual optimization strategy: First, it activates the local auxiliary fill light LEDs integrated on both sides of the main projection light source, with the fill light power controlled at 40%-50% of the main light source, to accurately fill light in the shadow area and avoid strong light diffusion interfering with the vision of surrounding people. Second, it automatically switches the color parameters of the projected sign, switching the original low-contrast color adapted to the strong light environment to a high-contrast color with high penetration, thereby improving the visual recognition of the sign in the shadow area.

[0105] This application also proposes an adaptive projection navigation system for outdoor navigation, the system's modules are shown in the diagram below. Figure 5 As shown, the navigation system includes:

[0106] Terminal partitioning unit 1 is used to configure the master and slave roles of the smart terminal cluster to determine the master device terminal and the slave device terminal, and to establish communication links between the master device terminal and the master projection module, and between the slave device terminal and the slave projection module, respectively.

[0107] The main navigation unit 2 is used to generate main navigation commands and secondary navigation commands based on navigation data through the main device terminal, convert the secondary navigation commands into low-frequency flashing codes, and transmit the main navigation commands and low-frequency flashing codes together to the main projection module.

[0108] The main projection unit 3 is used to generate a main navigation mark for the main navigation terminal carrier based on the main navigation command through the main projection module, and project the low-frequency flashing code onto the ground in front of the main navigation terminal carrier after superimposing the low-frequency flashing code into the main navigation mark, forming a projected navigation mark with low-frequency flashing code.

[0109] The navigation unit 4 is used to capture the projected navigation marks on the ground by the photosensitive decoding module built into the projection module and decode the navigation instructions from them, and then transmit the navigation instructions to the slave device terminal.

[0110] The projection unit 5 is used to generate a navigation identifier for the user of the navigation terminal based on the navigation instructions through the projection module, and to project the navigation identifier onto the ground in front of the user of the navigation terminal.

[0111] Those skilled in the art will understand that the modules described above can be implemented using general-purpose computing systems. They can be centralized on a single computing system or distributed across a network of multiple computing systems. Optionally, they can be implemented using computer-executable program code, allowing them to be stored in a storage system for execution by the computing system. Alternatively, they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0112] Note that the above description is merely a preferred embodiment and the technical principles employed in this application. Those skilled in the art will understand that this application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of this application, and the scope of this application is determined by the scope of the appended claims.

[0113] The above disclosures are only a few specific implementation scenarios of this application. However, this application is not limited to these. Any variations that can be conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. An adaptive projection navigation method for outdoor navigation, characterized in that, include: Configure the smart terminal cluster with master and slave roles to determine the master device terminal and slave device terminal, and establish communication links between the master device terminal and the master projection module, and between the slave device terminal and the slave projection module respectively; The main device terminal generates main navigation commands and secondary navigation commands based on navigation data, converts the secondary navigation commands into low-frequency flashing codes, and transmits the main navigation commands and low-frequency flashing codes together to the main projection module. The main projection module generates a main navigation identifier for the main navigation terminal carrier based on the main navigation command, and projects the low-frequency flashing code onto the ground in front of the main navigation terminal carrier after superimposing the low-frequency flashing code into the main navigation identifier, thus forming a projected navigation identifier with the low-frequency flashing code. The projection module captures the projected navigation markers on the ground and decodes the navigation instructions from them using the built-in photosensitive decoding module, and then transmits the navigation instructions to the slave device terminal. The projection module generates a navigation identifier for the user of the navigation terminal based on the navigation instructions, and projects the navigation identifier onto the ground in front of the user of the navigation terminal.

2. The adaptive projection navigation method according to claim 1, characterized in that, The navigation command is converted into a low-frequency flashing code using a binary encoding rule. The low-frequency flashing code has a frequency of 0.1Hz and a bit length of 4-8 bits. The main navigation command and the low-frequency flashing code are encapsulated into a unified data frame. The header of the data frame is the command type identifier, and the tail is the check code. The data frame is then transmitted to the main projection module through the established low-power Bluetooth link.

3. The adaptive projection navigation method according to claim 1, characterized in that, The main projection module has a built-in encoding driver module. After receiving the main navigation command, the encoding driver module calls the preset identifier template to generate the main navigation identifier. The main navigation identifier is in the shape of an arrow and is marked with the distance to the next node and a road condition warning icon. The encoding driver module superimposes the low-frequency flicker code onto the brightness adjustment link of the main navigation sign, thereby achieving synchronous low-frequency flicker during the projection process of the main navigation sign.

4. The adaptive projection navigation method according to claim 1, characterized in that, The photosensitive decoding module of the projection module is arranged coaxially with the projection lens, and the sensing range of the photosensitive decoding module matches the projection range of the projection lens in order to capture the low-frequency flickering signal in the projected navigation sign.

5. The adaptive projection navigation method according to claim 1, characterized in that, The photosensitive decoding module first filters the captured flashing signal, and then decodes the navigation command based on the preset binary encoding rules. After decoding, the projection module transmits the decoded navigation command to the corresponding slave device terminal via a Bluetooth Low Energy link. During the transmission, decoding verification information is carried. If the slave device terminal determines that the verification has failed, it will send a message back to the projection module to re-decode. If the photosensitive decoding module fails to capture a low-frequency flashing signal that meets the requirements for 5 consecutive seconds, or fails to decode and verify 3 times in a row, a disconnection warning signal will be triggered and transmitted to the slave device terminal.

6. The adaptive projection navigation method according to claim 1, characterized in that, Both the main projection module and the slave projection module are integrated into the head or chest of the corresponding terminal wearer; When worn on the head, the projection angle is downwards at 20°-30°, and the projection distance is 1.5-3m. When worn on the chest, the projection angle is downwards at 15°-25°, and the projection distance is 1-2m.

7. The adaptive projection navigation method according to claim 1, characterized in that, Also includes: By capturing the cadence signal of the corresponding terminal wearer through a preset cadence sensor, the projection brightness is continuously increased at the vibration peak of the cadence signal, decreased at the vibration trough of the cadence signal, and decreased in the static state and switched to a breathing flashing mode.

8. The adaptive projection navigation method according to claim 1, characterized in that, The main navigation identifier includes the direction of travel, distance information, and road condition warning information; The navigation identifier includes at least the direction of travel.

9. The adaptive projection navigation method according to claim 1, characterized in that, Also includes: Collect user motion characteristics and ambient brightness characteristics. Adjust the brightness parameters of the projected sign based on the motion characteristics. Determine whether the projected area is covered by human shadows based on the ambient brightness characteristics. If it is determined to be covered by shadows, trigger local supplemental lighting and switch the color parameters of the projected sign.

10. An adaptive projection navigation system for outdoor navigation, characterized in that, include: The terminal partitioning unit is used to configure the master and slave roles of the smart terminal cluster to determine the master device terminal and the slave device terminal, and to establish communication links between the master device terminal and the master projection module, and between the slave device terminal and the slave projection module, respectively. The main navigation unit is used to generate main navigation instructions and secondary navigation instructions based on navigation data through the main device terminal, convert the secondary navigation instructions into low-frequency flashing codes, and transmit the main navigation instructions and the low-frequency flashing codes together to the main projection module. The main projection unit is used to generate a main navigation identifier for the main navigation terminal carrier based on the main navigation command through the main projection module, and project the low-frequency flashing code onto the ground in front of the main navigation terminal carrier after superimposing the low-frequency flashing code into the main navigation identifier, forming a projected navigation identifier with the low-frequency flashing code. The navigation unit is used to capture the projected navigation marks on the ground through the photosensitive decoding module built into the projection module and decode the navigation instructions from them, and transmit the navigation instructions to the slave device terminal; The projection unit is used to generate a navigation identifier for the carrier of the navigation terminal based on the navigation instruction through the projection module, and to project the navigation identifier onto the ground in front of the carrier of the navigation terminal.

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