A locomotive position measurement method and system

Abstract

This invention discloses a locomotive position measurement method and system. The method includes installing a passive rack at the center or trackside of a rail sleeper; using a reading device fixed to the locomotive to read the physical characteristics of the passive rack and generate a corresponding status signal; decoding the status signal using a decoding device to calculate the locomotive's direction of movement and precise position. This invention achieves high-precision and high-reliability absolute position measurement of locomotives.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, and in particular to a locomotive position measurement method and system. Background Technology

[0002] At the iron discharge port of the railway locomotive ironmaking plant, the stopping accuracy is required to be within 10cm so that the ladle opening is aligned with the molten iron outlet.

[0003] Traditionally, the driver observes and controls the locomotive to align itself using a creeping motion. In automatic locomotive operation, this operation is necessary, requiring a measuring device to determine the locomotive's position and achieve precise positioning. Existing technologies typically employ the following methods: Option 1: Drawing inspiration from the positioning of the overhead crane system, the Gray busbar scheme is adopted. This scheme has an accuracy of approximately 5cm, but it is expensive and requires the installation of a source coil and corresponding signal generation and control circuit on the ground, as well as the installation of a reading antenna and decoding device on the locomotive. The disadvantages of this scheme are that the ground construction is complex and requires a power supply, which may limit its use at the molten iron unloading port.

[0004] Option 2: As Figure 1 As shown, a laser rangefinder sensor is used, and a reflective surface is placed above the locomotive in front of it. Theoretically, this method has high accuracy, but in practice, since the reflective surface is only 50cm*50cm, when the locomotive is measuring 30 meters away, the locomotive's vibration will cause the laser sensor to not be placed horizontally as theoretically possible. As a result, the laser point often cannot hit the reflecting surface, leading to inaccurate measurements. Furthermore, this method can only be used in places with end lines or earthen barriers.

[0005] Option 3: such as Figure 2 As shown, the traditional method involves laying racks on the ground and then using photoelectric sensors on moving objects to read the number of pulses for positioning. However, this method suffers from position loss during power outages. Furthermore, if the racks are too closely spaced, foreign objects may clog the gaps, leading to positioning failure. Additionally, the positioning function is lost when the moving object moves back and forth.

[0006] Therefore, there is an urgent need for a locomotive position measurement method that can achieve accurate measurement of the locomotive's position through a simple scheme. Summary of the Invention

[0007] The purpose of this invention is to provide a locomotive position measurement method and system to achieve high-precision and high-reliability absolute position measurement of locomotives.

[0008] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, embodiments of the present invention provide a locomotive position measurement method, the method comprising: Install passive racks at the center or beside the rail sleepers; The physical characteristics of the passive rack are read using a reading head device fixed to the locomotive to generate corresponding status signals; The status signal is decoded by a decoding device, and the locomotive's direction of movement and precise position are calculated.

[0009] Furthermore, the passive rack has alternating teeth and slots to form multiple standard tooth-slot cycles; the passive rack is a long straight strip, and the teeth and slots have the same width; Both ends of the passive rack are provided with notches, and the width of the notches is half the width of the teeth or gaps; when two passive racks are spliced ​​together, their notches are spliced ​​together to form a gap. The thickness of the passive rack is less than the width of the teeth and the gaps.

[0010] Furthermore, the passive toothed rack includes a normal tooth gap region and at least one absolute position coding region. The absolute position coding region includes coding units of a first physical form and coding units of a second physical form. The normal tooth gap region includes a plurality of consecutively arranged coding units of the second physical form. Each of the coding units has the same predetermined physical length and represents a binary symbol through the physical structure of its internal teeth and slots; wherein, the physical form of the coding unit includes a first physical form and a second physical form; The coding unit of the first physical form represents binary code 1, and the coding unit of the second physical form represents binary code 0. The data frame structure of the absolute position coding area includes a start identifier, data bits, and an end identifier. The start identifier and the end identifier are asymmetrical. The data bits constitute a unique absolute position identifier for each passive rack through several first physical form coding units and second physical form coding units.

[0011] Furthermore, the predetermined physical length of each coding unit is equal to the length of two standard slotted units. The first physical form of the encoding unit includes a long tooth consisting of three consecutive teeth and a slit, to represent binary code 1; the long tooth is formed by sealing the slit within a standard tooth slit unit; The coding unit of the second physical form includes two standard toothed units to represent binary code 0; The starting identifier in the absolute position encoding area is two consecutive encoding units of the first physical form, forming binary code 11; The end marker in the absolute position encoding area includes a second physical form encoding unit and a first physical form encoding unit, forming binary code 01.

[0012] Furthermore, the passive rack installed at the center or beside the rail sleeper includes: The passive rack is installed horizontally and vertically at the center of the rail sleeper or beside the rail via an mounting plate, and several passive racks can be spliced ​​together. The passive rack and the mounting plate are fixedly connected by several L-shaped fasteners. The mounting plate has several fixing holes and is fixed to the ground by fixing holes and bolts.

[0013] Furthermore, the step of using a reading head device fixed to the locomotive to read the physical characteristics of the passive rack and generate a corresponding status signal includes: The reading head device is installed at the bottom of the locomotive, and the reading head device includes three photoelectric sensors with a width smaller than the tooth width; wherein, each group of photoelectric sensors includes a transmitting light device and a receiving light device; When the locomotive moves, the reading head device reads the physical characteristics of the teeth and gaps on the passive rack through photoelectric sensors. Each photoelectric sensor outputs a combination of high level 1 or low level 0 depending on whether it is aligned with the teeth or gap, generating a status signal. This causes the reading head device to generate a sequence of status signals that change over time. The status signal generated by the reading head device is a 3-bit binary number. When the reading head device is not moving onto the passive rack, the status signal is 000. Each photoelectric sensor outputs a high level (1) or a low level (0) depending on whether it is aligned with the teeth or gaps, including: When a photoelectric sensor is blocked by a tooth, it outputs a high level 1; when a photoelectric sensor is in a gap and not blocked by a tooth, it outputs a low level 0.

[0014] Furthermore, the step of decoding the status signal using a decoding device and calculating the locomotive's direction of movement and precise position includes: Based on the characteristics of the status signal, the decoding device switches between a first working mode and a second working mode; In response to a state signal characterizing the normal tooth gap region, the decoding device, in a first operating mode, determines the relative displacement between the read head device and the passive rack through decoding. In response to a status signal characterizing the absolute position encoding area, the decoding device decodes the absolute position encoding area in a second operating mode to determine the locomotive's direction of movement and the current absolute position identifier of the passive rack. Based on the absolute position of the current passive rack, and combined with the relative displacement between the reading head device and the current passive rack, the precise position of the locomotive is obtained.

[0015] Furthermore, based on the characteristics of the state signal, the decoding device switches between a first operating mode and a second operating mode, including: The decoding device triggers a switch in its operating mode by identifying whether the status signal is an abnormal signal. If the decoding device detects that the status signal is not an abnormal signal, it indicates that the reading head is moving in the normal tooth gap area, and the decoding device is in the first working mode; If the decoding device detects that the status signal is an abnormal signal, it indicates that the read head has entered the absolute position encoding area. The decoding device switches from the first working mode to the second working mode and decodes the corresponding absolute position encoding area. After successful decoding, the decoding device switches back to the first working mode and continues to calculate the relative displacement. The abnormal signal is a stable high-level signal that continuously represents the gap being blocked; the stable high-level signal is 111, and its corresponding code is 1; that is, when the status signal is 111, it indicates that the reading head device has entered the absolute position encoding area of ​​the passive rack.

[0016] Furthermore, in the first operating mode, the decoding device determines the relative displacement between the reading head device and the rack by decoding, including: When the decoding device is in the first working mode, the relative displacement is calculated by tracking the cyclic change sequence of the state signal; Specifically, when the reading head device moves from the outside to the passive rack, remains powered on, and is located in the normal tooth gap area, the reading head device determines the locomotive's direction of movement through the status signal corresponding to the normal tooth gap area: If the locomotive travels from left to right, the status signal will cycle through the sequence 001, 011, 010, 110, 100, 101. If the locomotive travels from right to left, the status signal will cycle through the signal in reverse order.

[0017] Furthermore, the decoding device, in the second operating mode, decodes the absolute position encoding area to determine the locomotive's direction of movement and the current absolute position marker of the passive rack, including: When the decoding device is in the second working mode, the decoding device determines the locomotive's direction of movement by identifying the order of the start and end markers in the data frame structure of the absolute position encoding area, and decodes the data bits located between the start and end markers to obtain the absolute position marker of the passive rack. In the process of identifying the start and end markers in the data frame structure of the absolute position encoding area: if the start marker is identified but the end marker is not successfully identified within the predetermined data bit length, the data bit encoding read this time is determined to be invalid and wait to be read again; if the start marker is identified and the end marker is successfully identified within the predetermined data bit length, the data bit encoding read this time is determined to be valid.

[0018] Furthermore, based on the absolute position marker of the current passive rack, combined with the relative displacement between the reading head device and the current passive rack, the precise position of the locomotive is obtained, including: When the reading head device moves and reads the absolute position encoding area of ​​the current passive rack, the decoding device is in the first working mode and simultaneously decodes to obtain the locomotive's moving direction and the absolute position identifier of the current passive rack, thus obtaining the train's precise position. When the reading head device continues to move away from the absolute position encoding area of ​​the current source rack and is in the normal tooth gap area, the decoding device is in the second working mode. The decoding device calculates the relative displacement between the reading head device and the passive rack by tracking the cyclic change sequence of the status signal sent by the reading head device, and performs cumulative tracking calculation of the train position by combining the previous absolute position mark, until the latest absolute position mark of the passive rack is obtained by decoding again.

[0019] Secondly, embodiments of the present invention provide a locomotive position measurement system, the system comprising a passive rack, a reader, and a decoding device. The passive rack is installed at the center of the rail sleeper or beside the rail. The reading head device is fixed on the locomotive and is used to read the physical characteristics of the passive rack to generate corresponding status signals. The decoding device is connected to the reading head device. The decoding device is used to receive the status signal and decode it to calculate the locomotive's direction of movement and precise position.

[0020] The technical effects and advantages of this invention are as follows: 1. This invention achieves a measurement accuracy of up to ±3.5mm by using three photoelectric sensors to precisely scan the tooth gaps of the rack, which is far higher than the 10cm parking accuracy requirement in the prior art; by setting a physical coding area on the passive rack and decoding the "start identifier-data bit-end identifier" data frame, the unique absolute position identifier of the passive rack is obtained, which completely solves the industry problem of traditional photoelectric encoders losing position due to power failure and realizes true absolute position measurement. 2. The core ground device is a passive rack and pinion, which eliminates the need for power supply, wiring, and complex signal control equipment, greatly simplifying trackside facilities and reducing material and installation costs. At the same time, the passive rack and pinion is easy to process, adopts a modular design, can be quickly assembled and installed, has a short construction cycle, and has little impact on the modification of existing tracks. 3. The tooth and slot width of the passive rack are both designed to be 10mm. The larger gaps effectively avoid the risk of being blocked by foreign objects in harsh environments such as dust, rain, and snow, ensuring reliable reading by the reading head device. The decoding device adopts a dual-working-mode intelligent switching mechanism, updating the locomotive's absolute position only after recognizing a valid encoded frame. By verifying the integrity of the start / end markers, it effectively filters out erroneous signals caused by vibration and transient interference, making the measurement system highly fault-tolerant. At the same time, the guide groove design ensures the stability of the relative position between the reading head and the rack, further eliminating measurement errors. 4. Utilizing asymmetric start and end markers, the measurement system can automatically and quickly determine the locomotive's direction of travel without the need for additional direction sensors. The measurement is based on physical tooth gap triggering, independent of the locomotive's speed, and can provide stable and reliable position data in both low-speed creep and high-speed operation phases. The state machine logic inside the decoder can not only calculate the position but also achieve self-diagnosis of photoelectric sensor faults by monitoring whether the signal sequence conforms to a predetermined pattern.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the measurement in Scheme 2 of the prior art; Figure 2 This is a schematic diagram of the measurement in scheme 3 of the prior art; Figure 3 This is a flowchart of a locomotive position measurement method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the passive rack structure in an embodiment of the present invention; Figure 5 This is a schematic diagram of the passive rack and mounting plate in an embodiment of the present invention; Figure 6 This is a schematic diagram of the read head device in an embodiment of the present invention; Figure 7 This is a schematic diagram showing the relative positions of the reading head device and the passive rack in an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of code 1 and code 0 on the passive rack in an embodiment of the present invention; Figure 9 This is a schematic diagram of the reader device located in the encoding 1 area in an embodiment of the present invention; Figure 10 This is a schematic diagram of the reader device located in the encoding 0 region in an embodiment of the present invention; Figure 11 This is a schematic diagram of a locomotive position measurement system according to an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] To address the shortcomings of existing technologies, this invention discloses a locomotive position measurement method, such as... Figure 3 As shown, it includes the following steps: Step S1: Install a passive rack at the center or side of the rail sleeper; Step S2: Use the reading head device fixed to the locomotive to read the physical characteristics of the passive rack and generate the corresponding status signal; Step S3: Decode the status signal using a decoding device and calculate the locomotive's direction of movement and precise position.

[0026] In some specific embodiments, step S1: installing a passive rack at the center position or railside position of the rail sleeper includes the following: like Figure 4As shown, this embodiment preferably uses aluminum material processed into passive racks, which have the advantages of high temperature resistance, corrosion resistance, and light weight. The passive racks are long, straight structures, with each rack being 1 meter long for easy transportation and on-site installation. Each passive rack has alternating teeth and slots, with both teeth and slots being 10 mm wide. The thickness of the passive rack is less than the width of the teeth and slots (1 mm), thus preventing dust accumulation from clogging the slots. Each passive rack has notches at both ends, with the notch width being half the width of the slots and teeth, i.e., 5 mm. When two passive racks are installed together, the two notches naturally join to form a 10 mm standard brick gap, ensuring the uniformity of the gap width throughout the entire line.

[0027] like Figure 5 As shown, the passive rack is installed horizontally and vertically at the center of the rail sleeper or beside the rail via a mounting plate, according to the attached... Figure 5 As the mounting plate is the same length as the passive rack, several passive racks can be linearly spliced ​​together using the mounting plate. The mounting plate has several fixing holes, allowing it to be fixed to the sleeper with anchor bolts. Alternatively, it can be welded to a specially cast concrete column beside the rail. The passive rack is fixed to the mounting plate using several L-shaped fasteners, ensuring its long-term stability. The mounting position of the mounting plate and passive rack can be chosen at the center of the sleeper between two rails or on the outer edge of the rails; the specific installation can be adjusted according to site space, collision protection requirements, and actual conditions.

[0028] In some specific embodiments, step S2: using a reader device fixed to the locomotive to read the physical characteristics of the passive rack and generate a corresponding state signal, includes: like Figure 6 As shown, the reader in this embodiment consists of three photoelectric sensors arranged side-by-side. Each photoelectric sensor is 8mm wide and U-shaped with a 10mm opening. Each photoelectric sensor includes a transmitting light device and a receiving light device, so the total length of the three photoelectric sensors is 24mm. However, the photosensitive element is located at the center of each sensor. Therefore, after the three photoelectric sensors are joined together, the distance between the two outermost photosensitive elements is 4+8+4=16mm, which is less than 20mm. The passive rack is 1mm thick. Since the distance between the transmitting and receiving light devices of the photoelectric sensors is 10mm, there is a margin of approximately ±4mm. Figure 7 The diagram shows the relative positions of the read head device and the passive rack.

[0029] In this embodiment, the reader is installed at the bottom of the locomotive. Since the locomotive runs on the track, the passive rack is positioned between the transmitting and receiving optical components of the reader. This ensures that the U-shaped opening of the reader faces and encloses the passive rack, and is parallel to the rack's plane. Furthermore, in practical applications, to further ensure that the relative position between the reader and the passive rack does not shift vertically or horizontally due to vibration during locomotive operation, a guide groove can be added around the passive rack. The U-shaped structure of the reader can be embedded in the guide groove, thereby completely eliminating positional errors and ensuring the stability of the read signal.

[0030] As the locomotive moves, the reading head device reads the physical characteristics of the teeth and gaps on the passive rack using photoelectric sensors. Each photoelectric sensor outputs a high level (1) or a low level (0) depending on whether it is aligned with a tooth or gap, causing the three photoelectric sensors to generate a status signal. This, in turn, causes the reading head device to generate a sequence of status signals that change over time. The status signal generated by the reading head device is a 3-bit binary number. When the reading head device is not moving onto the passive rack, the status signal is 000 (combined with the set data format, the final status signal is 0B000).

[0031] Each photoelectric sensor outputs a high level 1 or a low level 0 depending on whether it is aligned with the teeth or gaps. Specifically, when a photoelectric sensor is blocked by a tooth, it outputs a high level 1, meaning the status code of a single photoelectric sensor is 1 when it is blocked; when a photoelectric sensor is in a gap and not blocked by a tooth, it outputs a low level 0, meaning the status code of a single photoelectric sensor in the gap is 0.

[0032] As the locomotive moves, the 3-bit binary status signal follows a fixed cyclic pattern: When the reading head device moves onto the passive rack and follows the locomotive from left to right (i.e., in the forward direction), the reading head device reads and generates a status signal that cycles through the sequence 0B001, 0B011, 0B010, 0B110, 0B100, 0B101 (i.e., a cycle of 6 status codes). When the reading head device moves onto the passive rack and runs in the opposite direction, the cycle is reversed (i.e., a reverse cycle of the 6 status codes). Therefore, the status signal in this invention is a cyclical sequence that changes over time.

[0033] The status reading method in this embodiment is not affected by the movement speed of the reading head device. Furthermore, through analysis, this reading head device can provide 6 status codes within a distance of 20mm, thus achieving a measurement accuracy of 3.3mm, which is far greater than the actual field requirements.

[0034] In some specific embodiments, the method further includes setting the encoding structure of the passive rack, including the following: Since passive racks lack rack coding, only the relative position of the locomotive can be calculated based on the status signals generated by the reading device. Furthermore, while theoretically the reading device can continuously acquire its position by following the cyclical rule of six status codes once it enters the passive rack area from the outside, as long as the entire measurement system remains powered on, if the system is powered on or off within the passive rack area and then powered on again, it will not read the starting point position 0B001, thus failing to obtain the correct position. To solve this problem, position coding of the passive racks is required (giving each passive rack a unique absolute position identifier). This ensures that whenever the system is powered on or off within the rack area, regardless of whether the movement is in the forward or reverse direction, a new position code is read, re-establishing the position coordinates to obtain the locomotive's absolute position.

[0035] Therefore, as Figure 7 As shown, in this invention, the entire passive rack is physically divided into two main regions: a normal tooth gap region and at least one absolute position encoding region; the absolute position encoding region includes encoding units of a first physical form and encoding units of a second physical form, and the normal tooth gap region includes multiple consecutively arranged encoding units of the second physical form; each encoding unit has the same predetermined physical length (40mm in this embodiment, i.e., the length of two standard tooth gap units), and represents a binary code element through the physical structure of its internal teeth and gaps; the physical form of the encoding unit includes the first physical form and the second physical form.

[0036] The normal tooth gap area is the main body of the passive toothed rack, with physical specifications of 10mm tooth width, 10mm gap width, and 1mm rack thickness. In this embodiment, the physical length (40mm) of two tooth gap units constitutes one coding unit, and two standard tooth gap units constitute a coding unit of the second physical form; therefore, the normal tooth gap area consists entirely of standard tooth gap units: tooth (10mm) + gap (10mm) = 20mm. This design ensures that the larger gap is not easily blocked by foreign objects such as dust and snow, resulting in high reliability.

[0037] like Figure 8 As shown, the absolute position coding area is a special section discretely distributed on the passive rack, and its function is to provide an absolute position reference for the entire measurement system; the absolute position coding area includes a first physical form coding unit and a second physical form coding unit; the first physical form coding unit represents binary code 1, and the second physical form coding unit represents binary code 0.

[0038] Specifically, the absolute position encoding area achieves binary data encoding by sealing the gaps in the passive rack (a physical means) to generate two physically shaped encoding units; as follows: (1) Code 1: like Figure 9 As shown, a standard 10mm gap is completely sealed with high-temperature resistant metal tape, thereby forming a 30mm long tooth + a standard 10mm gap between two standard toothed units, which generates the first physical form of the coding unit, and represents the binary code 1.

[0039] When the reader begins to pass through the encoding unit of the first physical form, the photoelectric sensors are continuously blocked in the long tooth area because the gap is blocked. Since the total length of the three photoelectric sensors is 16mm, the three photoelectric sensors will continuously output a high level, generating a status signal of 111 (combined with the set data format, the final status signal is 0B111). This indicates that the reader is currently reading code 1. When the reader reads the gap in the encoding unit of the first physical form, the generated status signal is 010 (combined with the set data format, the final status signal is 0B010). Since the previous status signal 0B111 can already indicate that the encoding unit of the first physical form has been read, the 0B010 at the gap needs to be discarded.

[0040] (2) Code 0: like Figure 10 As shown, the toothed slot units are not sealed, and two consecutive standard toothed slot units (with a total length of 40mm) are retained, which are the coding units of the second physical form, and are used to represent binary code 0.

[0041] When the reader passes through this area, the output signal of the photoelectric sensor will be encoded normally, and the generated status signal will be cyclically executed in the order of 0B001, 0B011, 0B010, 0B110, 0B100, 0B101 (i.e., the forward / reverse cycle of the 6 status codes); thus, two OB010 status signals representing the gap will appear one after another.

[0042] In this embodiment, a complete data frame of the absolute position coding area is formed by combining code 1 and code 0 according to specific rules. The data frame structure of the absolute position coding area includes a start identifier, data bits, and an end identifier. The start identifier and the end identifier are asymmetrical to facilitate the identification of the locomotive's direction of movement. The data bits form the absolute position identifier (i.e., unique identifier) ​​of the passive rack through several first physical form coding units and second physical form coding units.

[0043] Specifically, the start identifier in the absolute position coding area is composed of two consecutive first physical form coding units, namely two consecutive codes 1, forming binary code 11; the start identifier is used for the beginning of a data frame.

[0044] The end identifier in the absolute position coding area includes a second physical form coding unit and a first physical form coding unit, forming binary code 01; the end identifier is used to identify the end of a data frame.

[0045] The data bits include several encoding units of a first physical form and several encoding units of a second physical form, i.e., multi-bit encoding; for example, if there are 32 passive racks, then 5-bit binary encoding (2 5 =32), that is, the content of the data bits xxxxx is the absolute position identifier (such as absolute ID number) of each of the 32 passive racks. After adding the start and end identifiers, the complete frame is 11xxxxx01 (for example, 111100101 corresponds to rack ID=25).

[0046] In this embodiment, the present invention designs a rule of encoding 1 and encoding 0 on the passive rack, that is, in the subsequent position measurement process, the number of passive racks is encoded with arbitrary length, and the absolute position identifier of the passive rack is obtained by encoding parsing, so as to determine which passive rack the reading head device has read, and thus the train position can be accurately calculated.

[0047] In some specific embodiments, step S3: decoding the status signal using a decoding device and calculating the locomotive's direction of movement and precise position, including the following: In this embodiment, a microcontroller is used as the decoding device; the decoding device reads the status signal (e.g., OB000) sent by the reading head device; when the decoding device reads B000, it means that the reading head device has not entered the passive rack; when the decoding device reads 0B100 or 0B001, it means that the reading head device has started to enter the passive rack.

[0048] The core of the decoding device is a dual-mode intelligent switching mechanism.

[0049] When the system is powered on, the decoding device defaults to the first working mode (i.e., state machine counting mode). When the read head moves from the outside and moves within the normal tooth gap area, the three photoelectric sensors output status signals. The status signals cycle in a forward or reverse sequence of 0B001, 0B011, 0B010, 0B110, 0B100, 0B101 (i.e., a forward or reverse cycle of the 6 status codes). Each time the read head completes a full cycle, the decoder decodes and obtains the distance (20mm) of the read head transposed and moved by a standard tooth gap unit.

[0050] (1) Therefore, when the decoding device is in the first working mode, it receives the status signal sent by the reading head device and performs decoding. It tracks the cyclic changes of the status signal through a cyclic counting or interpolation algorithm to calculate the relative displacement between the reading head device and the passive rack with an accuracy of 3.3 mm (a status signal that gives 6 data within a 20 mm distance).

[0051] If the reading head device moves from the outside to the passive rack, remains powered on, and is located in the normal tooth gap area, the reading head device can determine the locomotive's direction of movement solely through the status signal corresponding to the normal tooth gap area: if the locomotive is traveling from left to right, the sensor status signal cycles through the sequence OB001, OB011, OB010, OB110, OB100, OB101; if the locomotive is traveling from right to left, the signal cycles through the signal in reverse order.

[0052] When the reader moves through the normal tooth gap area on the passive rack, the status signal changes regularly. However, once the reader moves to the absolute position encoding area on the passive rack, the abrupt change in the physical characteristics of the passive rack causes the status signal to become abnormal. Therefore, the switching of the decoding device's operating mode depends on whether the characteristics of the status signal are abnormal. When the decoding device identifies the status signal as abnormal, that is, when it identifies the status signal as abruptly changing from a normal regular change to a continuous and stable OB111 (i.e., encountering encoding 1), the decoding device switches from the first operating mode to the second operating mode and decodes the corresponding absolute position encoding area.

[0053] (2) When the decoding device is in the second working mode (data frame encoding mode), the decoding device pauses the counting of relative displacements and starts parsing the data frames in the absolute position encoding area, specifically including: Movement direction determination: First, identify the order of the start and end markers in the data frame structure of the current absolute position encoding area to determine the locomotive's movement direction. If the reader device reads code 11 first and then code 01, it indicates that the locomotive's movement direction is forward. If the reader device reads code 10 first (i.e., the reverse signal of code 01) and then code 11, it indicates that the locomotive's movement direction is reverse.

[0054] Data Decoding: The decoding device decodes the data bits between the start and end markers. It identifies whether the signal of the data bit is a continuous OB111 (i.e., code 1) or a changing signal containing OB010 (i.e., code 0) to interpret the binary value of each data bit. By decoding the data bits in the data frame structure of the current absolute position coding area, the absolute position identifier (e.g., absolute ID number) of the corresponding passive rack is obtained.

[0055] Data frame verification: The decoding device verifies whether the end marker (encoding 01) has been successfully identified within the predetermined data bit length, starting from the beginning identifier (encoding 11). If so, the data bit encoding read this time is valid; otherwise, the data bit encoding read this time is invalid, the data is discarded, and the device waits for the next reread.

[0056] Mode switchback: After successful decoding, the decoding device has successfully obtained the absolute position identifier (e.g., absolute ID number) of the current passive rack, and then switches back to the first working mode to continue calculating the relative displacement between the reading device and the current passive rack.

[0057] (3) Based on the absolute position identifier obtained by the decoding device in the second working mode, combined with the relative displacement calculated by the decoder in the first working mode, the precise position of the locomotive is calculated, specifically including: When the reading head device moves and reads the absolute position encoding area of ​​the current passive rack, the decoding device is in the first working mode and simultaneously decodes to obtain the locomotive's moving direction and the absolute position identifier of the current passive rack, thus obtaining the train's precise position. When the reading head device continues to move away from the absolute position encoding area of ​​the current source rack and into the normal tooth gap area, the decoding device is in the second working mode. The decoding device calculates the relative displacement between the reading head device and the passive rack by tracking the cyclic change sequence of the status signal sent by the reading head device; and performs cumulative tracking calculation of the train position based on the previous absolute position identifier and the relative displacement, until the latest absolute position identifier of the passive rack is obtained through decoding again.

[0058] That is, the formula for calculating the precise position of the locomotive is: When the reader is in the absolute position encoding area: Absolute position = (absolute ID number of passive rack × rack unit length); When the reading head device is in the normal tooth gap area: Absolute position = (absolute ID number of passive rack × rack unit length) + relative displacement on the current passive rack; For example, if the starting point of the 25th passive rack is at 24 meters, and the reading head device moves another 453.7 mm on the passive rack, then the final absolute position is 24 + 0.4537 = 24.4537 meters.

[0059] This invention utilizes a passive rack and pinion mechanism combined with three photoelectric sensors to form a reading head device. This device achieves precise locomotive position measurement, independent of its direction and speed of movement. Furthermore, the passive rack is simple to manufacture, the designed encoding rules are easy to implement, and it does not accumulate dust, making it feasible for large-scale applications in harsh environments. Because the changes in the corresponding photoelectric sensors during the movement of the reading head device are predictable, any deviation from this predictable pattern indicates a sensor malfunction, allowing for timely system alarm processing. This invention perfectly combines high-precision relative measurement with a reliable absolute reference, ensuring millimeter-level accuracy while solving the industry-wide problem of position loss during power outages.

[0060] Based on the same inventive concept, embodiments of the present invention disclose a locomotive position measurement system, such as... Figure 11 As shown, the system includes a passive rack, a reader, and a decoding device. The passive rack is installed at the center of the rail sleeper or beside the rail. The reading head device is fixed on the locomotive and is used to read the physical characteristics of the passive rack to generate corresponding status signals. The decoding device is connected to the reading head device. The decoding device is used to receive the status signal and decode it to calculate the locomotive's direction of movement and precise position.

[0061] Regarding the system in the above embodiments, the specific manner in which each unit module performs operations has been described in detail in the embodiments related to the method, and will not be elaborated here.

[0062] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for measuring locomotive position, characterized in that, The method includes: Install passive racks at the center or beside the rail sleepers; A reading head device fixed to the locomotive is used to read the physical characteristics of the passive rack and generate a status signal; The status signal is decoded by a decoding device, and the locomotive's direction of movement and precise position are calculated. The status signal is decoded by a decoding device, and the locomotive's direction of movement and precise position are calculated, including: Based on the characteristics of the status signal, the decoding device switches between a first working mode and a second working mode; In response to a state signal characterizing a normal tooth gap region, the decoding device, in a first operating mode, determines the relative displacement between the read head device and the passive rack through decoding. In response to a status signal characterizing the absolute position encoding area, the decoding device decodes the absolute position encoding area in a second operating mode to obtain the locomotive's direction of movement and the current absolute position identifier of the passive rack. Based on the absolute position of the current passive rack, combined with the relative displacement between the reading head device and the current passive rack, the precise position of the locomotive is obtained; Based on the characteristics of the state signal, the decoding device switches between a first operating mode and a second operating mode, including: The decoding device triggers a switch in its operating mode by identifying whether the status signal is an abnormal signal. If the decoding device detects that the status signal is not an abnormal signal, it indicates that the reading head is moving in the normal tooth gap area, and the decoding device is in the first working mode; If the decoding device detects that the status signal is an abnormal signal, it indicates that the read head has entered the absolute position encoding area. The decoding device switches from the first working mode to the second working mode and decodes the corresponding absolute position encoding area. After successful decoding, the decoding device switches back to the first working mode and continues to calculate the relative displacement. The abnormal signal is a stable high-level signal that continuously represents the gap being blocked; the stable high-level signal is 111, and its corresponding code is 1; that is, when the status signal is 111, it indicates that the reading head device has entered the absolute position encoding area of ​​the passive rack.

2. The locomotive position measurement method according to claim 1, characterized in that, The passive rack has alternating teeth and slots to form multiple standard tooth-slot cycles; the passive rack is a long straight strip, and the teeth and slots have the same width; Both ends of the passive rack are provided with notches, and the width of the notches is half the width of the teeth or gaps; when two passive racks are spliced ​​together, their notches are spliced ​​together to form a gap. The thickness of the passive rack is less than the width of the teeth and the gaps.

3. A locomotive position measurement method according to claim 1 or 2, characterized in that, The passive toothed rack includes a normal tooth gap region and at least one absolute position coding region. The absolute position coding region includes coding units of a first physical form and coding units of a second physical form. The normal tooth gap region includes a plurality of consecutively arranged coding units of the second physical form. Each of the coding units has the same predetermined physical length and represents a binary symbol through the physical structure of its internal teeth and slots; wherein, the physical form of the coding unit includes a first physical form and a second physical form; The coding unit of the first physical form represents binary code 1, and the coding unit of the second physical form represents binary code 0. The data frame structure of the absolute position coding area includes a start identifier, data bits, and an end identifier. The start identifier and the end identifier are asymmetrical. The data bits constitute a unique absolute position identifier for each passive rack through several first physical form coding units and second physical form coding units.

4. The locomotive position measurement method according to claim 3, characterized in that, The predetermined physical length of each coding unit is equal to the length of two standard slotted units. The first physical form of the encoding unit includes a long tooth consisting of three consecutive teeth and a slit, to represent binary code 1; the long tooth is formed by sealing the slit within a standard tooth slit unit; The coding unit of the second physical form includes two standard toothed units to represent binary code 0; The starting identifier in the absolute position encoding area is two consecutive encoding units of the first physical form, forming binary code 11; The end marker in the absolute position encoding area includes a second physical form encoding unit and a first physical form encoding unit, forming binary code 01.

5. The locomotive position measurement method according to claim 1, characterized in that, The passive rack installed at the center or beside the rail sleeper includes: The passive rack is installed horizontally and vertically at the center of the rail sleeper or beside the rail via an mounting plate, and several passive racks can be spliced ​​together. The passive rack and the mounting plate are fixedly connected by several L-shaped fasteners. The mounting plate has several fixing holes and is fixed to the ground by fixing holes and bolts.

6. The locomotive position measurement method according to claim 2, characterized in that, The process of using a reading head device fixed to the locomotive to read the physical characteristics of the passive rack and generate a status signal includes: The reading head device is installed at the bottom of the locomotive, and the reading head device includes three photoelectric sensors with a width smaller than the tooth width; wherein, each group of photoelectric sensors includes a transmitting light device and a receiving light device; When the locomotive moves, the reading head device reads the physical characteristics of the teeth and gaps on the passive rack through photoelectric sensors. Each photoelectric sensor outputs a combination of high level 1 or low level 0 based on whether it is aligned with the teeth or gaps to generate a status signal. This causes the reading head device to generate a sequence of status signals that change over time during the locomotive's movement. Each status signal is a 3-bit binary number. When the reading head device is not moving onto the passive rack, the status signal is 000. Each photoelectric sensor outputs a high level (1) or a low level (0) depending on whether it is aligned with the teeth or gaps, including: When a photoelectric sensor is blocked by a tooth, it outputs a high level 1; when a photoelectric sensor is in a gap and not blocked by a tooth, it outputs a low level 0.

7. The locomotive position measurement method according to claim 1, characterized in that, The decoding device, in its first operating mode, determines the relative displacement between the reading head and the rack through decoding, including: When the decoding device is in the first working mode, the relative displacement is calculated by tracking the cyclic change sequence of the state signal; Specifically, when the reading head device moves from the outside to the passive rack, remains powered on, and is located in the normal tooth gap area, the reading head device determines the locomotive's direction of movement through the status signal corresponding to the normal tooth gap area: If the locomotive travels from left to right, the status signal will cycle through the sequence 001, 011, 010, 110, 100, 101. If the locomotive travels from right to left, the status signal will cycle through the signal in reverse order.

8. The locomotive position measurement method according to claim 1, characterized in that, The decoding device, in its second operating mode, decodes the absolute position encoding area to determine the locomotive's direction of movement and the current absolute position marker of the passive rack, including: When the decoding device is in the second working mode, the decoding device determines the locomotive's direction of movement by identifying the order of the start and end markers in the data frame structure of the absolute position encoding area, and decodes the data bits located between the start and end markers to obtain the absolute position marker of the passive rack. In the process of identifying the start and end markers in the data frame structure of the absolute position encoding area: if the start marker is identified but the end marker is not successfully identified within the predetermined data bit length, the data bit encoding read this time is determined to be invalid and wait to be read again; if the start marker is identified and the end marker is successfully identified within the predetermined data bit length, the data bit encoding read this time is determined to be valid.

9. The locomotive position measurement method according to claim 1, characterized in that, Based on the absolute position marker of the current passive rack, and combined with the relative displacement between the reading head device and the current passive rack, the precise position of the locomotive is obtained, including: When the reading head device moves and reads the absolute position encoding area of ​​the current passive rack, the decoding device is in the first working mode and simultaneously decodes to obtain the locomotive's moving direction and the absolute position identifier of the current passive rack, thus obtaining the train's precise position. When the reading head device continues to move away from the absolute position encoding area of ​​the current source rack and is in the normal tooth gap area, the decoding device is in the second working mode. The decoding device calculates the relative displacement between the reading head device and the passive rack by tracking the cyclic change sequence of the status signal sent by the reading head device, and performs cumulative tracking calculation of the train position by combining the previous absolute position mark, until the latest absolute position mark of the passive rack is obtained by decoding again.

10. A locomotive position measurement system, characterized in that, The system includes a passive rack, a reader, and a decoding device. The passive rack is installed at the center of the rail sleeper or beside the rail. The reading head device is fixed on the locomotive and is used to read the physical characteristics of the passive rack to generate corresponding status signals. The decoding device is connected to the reading head device. The decoding device is used to receive the status signal and decode it to calculate the locomotive's direction of movement and precise position. The status signal is decoded by a decoding device, and the locomotive's direction of movement and precise position are calculated, including: Based on the characteristics of the status signal, the decoding device switches between a first working mode and a second working mode; In response to a state signal characterizing a normal tooth gap region, the decoding device, in a first operating mode, determines the relative displacement between the read head device and the passive rack through decoding. In response to a status signal characterizing the absolute position encoding area, the decoding device decodes the absolute position encoding area in a second operating mode to obtain the locomotive's direction of movement and the current absolute position identifier of the passive rack. Based on the absolute position of the current passive rack, combined with the relative displacement between the reading head device and the current passive rack, the precise position of the locomotive is obtained; Based on the characteristics of the state signal, the decoding device switches between a first operating mode and a second operating mode, including: The decoding device triggers a switch in its operating mode by identifying whether the status signal is an abnormal signal. If the decoding device detects that the status signal is not an abnormal signal, it indicates that the reading head is moving in the normal tooth gap area, and the decoding device is in the first working mode; If the decoding device detects that the status signal is an abnormal signal, it indicates that the read head has entered the absolute position encoding area. The decoding device switches from the first working mode to the second working mode and decodes the corresponding absolute position encoding area. After successful decoding, the decoding device switches back to the first working mode and continues to calculate the relative displacement. The abnormal signal is a stable high-level signal that continuously represents the gap being blocked; the stable high-level signal is 111, and its corresponding code is 1; that is, when the status signal is 111, it indicates that the reading head device has entered the absolute position encoding area of ​​the passive rack.

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