Method and device for measuring long-distance absolute position based on magnetic induction principle

Abstract

The invention discloses a long-distance absolute position measuring method and device based on a magnetic induction principle. The magnetic induction displacement sensor is fixed on the mobile equipment and moves along with the mobile equipment, a certain distance range is kept between the magnetic induction displacement sensor and the magnetic mark, and the magnetic mark is subjected to discrete point arrangement along the movement track of the mobile equipment according to a certain coding mode and is kept stationary. And the signal conversion module calculates real-time absolute position information of the magnetic induction displacement sensor relative to the magnetic mark according to the pulse signal output by the magnetic induction displacement sensor through a method, and outputs the real-time absolute position information to the mobile equipment data acquisition module. According to the magnetic induction absolute position positioning device and method based on interval coding, high-precision absolute position positioning with the precision reaching the millimeter level and the length reaching the kilometer level can be achieved, good environment adaptability of the device is ensured through non-contact measurement of the magnetic induction principle, the service life is long, and the positioning precision is high. And the method has high cost advantage and practical value.

Description

Technical Field

[0001] The invention relates to an absolute position measurement method and device, and in particular to a long-distance absolute position measurement method and device based on the magnetic induction principle. Background Art

[0002] Long-distance absolute position measurement technology is widely used in lifting equipment and automated factories. For example, it is used in unmanned intelligent driving, intelligent steel coil warehouses, gantry crane correction systems and other occasions that require absolute position positioning.

[0003] At present, there are optical measurement technologies for long-distance absolute position measurement, such as laser distance measurement, steel belt coding ruler (CN117516602A, an absolute position detection device and method), two-dimensional code distance measurement (CN108726369A, a long-distance positioning system for driving), etc. However, optical long-distance absolute position measurement technology is often used in some indoor areas with better environments such as no steam and dust. There are also magnetic induction measurements, such as CN206705544U (automatic positioning, stacking and loading eccentricity detection system for container gantry crane) and CN115417176A (automatic material distribution system for unloading trolley based on Gray bus); in the content disclosed in patent CN115417176A, Gray bus positioning system includes many components such as starting box, terminal box, Gray line, address transmitter, antenna box, address detector, etc., which has the problems of complex installation, easy damage and high replacement cost when replacing coding cable, and cannot be used in some outdoor occasions, and has many application limitations. For example, CN218566408U (a vehicle positioning system using a magnetic coding ruler) uses a magnetic coding ruler based on the Hall principle, and the coding rules are complex and difficult to mass produce.

[0004] Magnetostrictive displacement sensors are widely used in displacement detection of actuators such as hydraulic cylinders or pneumatic cylinders due to their high reliability, high precision, and non-contact characteristics. They are basically used for short-distance (generally less than 20 meters) displacement measurement, but have not yet been applied to long-range absolute position measurement. Summary of the invention

[0005] The present invention aims to solve the problems of the existing long-range positioning technology, such as complex structure, inconvenient buttons, and difficulty in using in outdoor environments such as steam, dust, and high temperature, and proposes a long-range absolute position positioning system (i.e., measuring device) based on the principle of magnetic induction. The encoding method and identification method proposed in the present invention have extremely high fault tolerance and anti-interference performance, and the magnetic mark installation method is very simple and easy to maintain, and the repeated positioning accuracy can reach ±0.5mm. It can be used in harsh outdoor environments such as high temperature, high humidity, and dust, and has obvious technical advantages and excellent environmental adaptability. The method and device proposed in the present invention can realize kilometer-level long-distance position measurement.

[0006] The technical solution adopted by the present invention is as follows:

[0007] 1. A long-distance absolute position measurement method based on the principle of magnetic induction

[0008] Step 1: construct a reference absolute position coding table, wherein the reference absolute position coding table includes interval coding and position coding;

[0009] Step 2: According to the reference absolute position coding table, magnetic markers are arranged in sequence along the motion trajectory of the mobile device, and the actual arrangement spacing of the magnetic markers is calibrated to obtain the actual absolute position coding table;

[0010] Step 3: Use the magnetic induction signal acquisition system installed in the mobile device to obtain the pulse signal of the magnetic mark under the mobile device;

[0011] Step 4: Select the incremental mode or the absolute mode according to the number of pulse signals of the acquired magnetic marker;

[0012] Step 5: Based on the actual absolute position encoding table, the validity of the pulse signal of the acquired magnetic mark is judged, and then the position information of the mobile device is calculated and output to complete the position measurement.

[0013] The reference absolute position coding table contains multiple groups of different and unique coding sequences, each group of coding sequences includes an interval code and N-1 position codes, and multiple magnetic marks corresponding to each group of coding sequences form an interval coding component; in two adjacent interval coding components, the distance between the first magnetic mark of the latter interval coding component and the last magnetic mark of the previous interval coding component is set to a fixed value.

[0014] The motion trajectory of the mobile device is a straight line, a curve, or a trajectory combining a straight line and a curve.

[0015] The step 4 is specifically as follows:

[0016] If the number of pulse signals of the magnetic marker currently acquired is greater than or equal to N+1, the working mode of the magnetic induction signal acquisition system is the absolute mode; if the number of pulse signals of the magnetic marker currently acquired is less than N+1, the working mode of the magnetic induction signal acquisition system is the incremental mode.

[0017] The step 5 is specifically as follows:

[0018] When the incremental mode is selected, the real-time position information is calculated by comparing with the actual absolute position encoding table, and the warning information is output.

[0019] When the absolute mode is selected, the validity of the pulse signal of the current magnetic mark is determined by comparing it with the actual absolute position coding table. If valid, the absolute position of the mobile device is calculated and output; if invalid, a new coding sequence is generated according to the pulse signal of the current magnetic mark, and the new coding sequence is stored in the actual absolute position coding table and updated, and then the absolute position of the mobile device is calculated and output.

[0020] The calculation and output of the absolute position of the mobile device is specifically as follows:

[0021] First, the interval code and position code of the pulse signal of the currently acquired magnetic mark are identified, and then the interval search is performed with the actual absolute position code table to obtain the matching interval code, and then the position code is compared with the matching interval code to obtain the absolute position of the mobile device.

[0022] 2. A long-distance absolute position measurement device based on the principle of magnetic induction

[0023] The measuring device includes a magnetic marker, a magnetic induction displacement sensor, a signal conversion module and a signal acquisition module. Several magnetic markers are arranged in sequence along the motion trajectory of the mobile device. A magnetic induction displacement sensor is fixedly installed at the bottom of the mobile device. The magnetic induction displacement sensor is connected to the signal conversion module, and the signal conversion module is connected to the signal acquisition module.

[0024] N magnetic marks are arranged in succession at intervals to form an interval coding component, N≥3; in each interval coding component, the distance between the N magnetic marks forms a unique coding sequence; in two adjacent interval coding components, the distance between the first magnetic mark of the latter interval coding component and the last magnetic mark of the previous interval coding component is set to a fixed value.

[0025] The sensing range of the magnetic induction displacement sensor covers at least N+1 magnetic marks.

[0026] When there are less than N+1 magnetic marks within the sensing range of the magnetic induction displacement sensor or the offset distance of the magnetic mark exceeds a preset offset threshold, the signal conversion module sends out an early warning signal and transmits it to the early warning module.

[0027] The above one or more technical solutions in the embodiments of the present invention have at least one or more of the following beneficial effects:

[0028] The long-range absolute position measurement device based on the magnetic induction principle of the present invention can realize non-contact induction of magnetic marks through magnetic induction displacement sensors, and realize millimeter-level high-precision absolute position measurement within a kilometer-level measurement range by arranging the magnetic marks according to certain coding rules. The actual maximum measurement range is related to the coding of the magnetic marks and can reach 2-3 kilometers or even larger.

[0029] The magnetic markers are arranged according to certain coding rules and remain unique within the measurement range of the entire measuring device, thereby ensuring that the measuring device can achieve absolute position measurement. The original measurement method based on magnetic induction can ensure that the entire measuring device can still output absolute position information after power failure and power-on again.

[0030] The method proposed in the present invention can avoid abnormal conditions such as magnetic mark deviation, excess, lack, etc., and the system can still output data normally, and can also output warning signals, thereby improving the anti-interference, robustness and maintainability of the system.

[0031] The non-contact induction magnetic induction measurement makes the use of long-range absolute position measurement devices based on the magnetic induction principle free of fatigue problems such as wear, and has a longer service life and is more stable.

[0032] The magnetic induction displacement sensor and the magnetic mark have good environmental adaptability, and the signal conversion module can be installed in the control cabinet of the mobile device, so that the measuring device can be used in harsh environments such as high temperature, high humidity, rain, dust, and outdoor.

[0033] In summary, the present invention is a long-range absolute position measurement device and method based on the principle of magnetic induction, which realizes millimeter high-precision absolute position measurement within a kilometer-level measurement range in harsh environments such as high temperature, high humidity, rain, dust, and outdoor. Its encoding method and recognition method have extremely high fault tolerance and anti-interference performance, and the system composition is simple and convenient, with extremely low maintenance cost, and has great practical value and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of a long-range absolute position measurement device based on the magnetic induction principle according to an embodiment of the present invention.

[0035] Figure 2 Schematic diagram of a long-range absolute position measurement method based on the magnetic induction principle according to an embodiment of the present invention.

[0036] Figure 3 The present invention is a flowchart of a long-range absolute position measurement method based on the magnetic induction principle according to an embodiment of the present invention.

[0037] In the figure: a magnetic marker 1, a magnetic induction displacement sensor 2, a signal conversion module 3, a connecting cable 4, a signal acquisition module 5, and a magnetic marker pulse waveform 21. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with the embodiments and drawings. Obviously, this is an embodiment of the present invention, but it is not limited thereto. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0039] like Figure 3 As shown, the present invention proposes a long-distance absolute position measurement method based on the magnetic induction principle, and the measurement method comprises the following steps:

[0040] Step 1: Construct a reference absolute position coding table, which includes interval coding and position coding; the reference absolute position coding table contains multiple groups of different and unique coding sequences, each group of coding sequences includes an interval coding and N-1 position coding, where the interval coding is used to identify the interval segment of the magnetic induction sensor, and the position coding is used to identify the absolute position information of the current code. The multiple magnetic marks 1 corresponding to each group of coding sequences form an interval coding component; in two adjacent interval coding components, the distance between the first magnetic mark 1 of the latter interval coding component and the last magnetic mark 1 of the previous interval coding component is set to a fixed value.

[0041] Step 2: According to the reference absolute position coding table, the magnetic markers 1 are arranged in sequence along the motion trajectory of the mobile device. Due to installation errors, there is an error between the preset position coding table and the actual position coding table, so the coding table needs to be calibrated. The magnetic induction sensor is used to measure the spacing of the magnetic markers 1 in sequence, that is, the actual spacing of the magnetic markers 1 is calibrated, so as to obtain the actual absolute position coding table and save it in the system; the motion trajectory of the mobile device is a straight line, a curve, or a combination of a straight line and a curve.

[0042] Step 3: Using the magnetic induction signal acquisition system installed in the mobile device to obtain the pulse signal of the magnetic mark 1 under the mobile device;

[0043] Step 4: The system selects the incremental mode or the absolute mode according to the number of pulse signals of the magnetic marker 1 obtained;

[0044] Step 4 is as follows:

[0045] If the number of pulse signals of magnetic marker 1 currently acquired is greater than or equal to N+1, the working mode of the magnetic induction signal acquisition system is absolute mode; if the number of pulse signals of magnetic marker 1 currently acquired is less than N+1, the working mode of the magnetic induction signal acquisition system is incremental mode.

[0046] Step 5: Based on the actual absolute position encoding table stored in the system, the validity of the pulse signal of the acquired magnetic mark 1 is judged, and then the position information of the mobile device is calculated and output to complete the position measurement.

[0047] Step 5 is as follows:

[0048] When the incremental mode is selected, the real-time position information is calculated by comparing with the actual absolute position encoding table saved in the system, and the warning information is output.

[0049] When the absolute mode is selected, the validity of the pulse signal of the current magnetic mark 1 is determined by comparing it with the actual absolute position coding table saved in the system. If valid, the absolute position of the mobile device is calculated and output; if invalid, a new coding sequence is generated according to the pulse signal of the current magnetic mark 1, and the new coding sequence is stored in the actual absolute position coding table of the system and updated, and then the absolute position of the mobile device is calculated and output.

[0050] Among them, the absolute position of the mobile device is calculated and output, specifically:

[0051] First, identify the interval code and position code of the pulse signal of the currently acquired magnetic mark 1, and then perform interval search with the actual absolute position code table stored in the system to obtain the matching interval code, and then compare the position code according to the matching interval code to obtain the absolute position of the mobile device. The real-time absolute position of the magnetic induction displacement sensor 2 relative to the magnetic mark 1 can be calculated using the following formula:

[0052]

[0053] Where, L i is the distance between the i+1th magnetic mark 1 and the ith magnetic mark 1, c is the propagation speed of the guided wave in the magnetic induction displacement sensor 2, t j is the time difference between the magnetic mark pulse 212 and the start pulse 211 of the jth magnetic mark 1 within the sensing range of the magnetic induction displacement sensor 2, S j is the real-time absolute position of the magnetic induction displacement sensor 2 relative to the magnetic mark 1 calculated based on the j-th magnetic mark 1.

[0054] This comparison method has the characteristics of high speed and low error rate. It can also calibrate the interval code and position code with each other and has good anti-interference ability.

[0055] When the signal conversion module 3 determines that the code of the magnetic mark 1 is inconsistent with the code table, that is, invalid, the signal conversion module 3 will output a warning message. If the signal conversion module 3 repeatedly confirms that the code is inconsistent, the spacing code of the magnetic mark 1 replaces the information in the code table, and then calculates the real-time absolute position of the magnetic induction displacement sensor 2 relative to the magnetic mark 1 according to the above formula based on the new code table. This processing method can ensure that the system can still work normally when the magnetic mark is abnormal, such as less or more magnetic mark 1, and when the magnetic mark 1 is offset relative to the original state, and also gives a warning message, which needs to be processed in time. The signal conversion module 3 converts the calculated real-time absolute position information of the sensor relative to the magnetic mark into a standard signal or bus output to the signal acquisition module 5.

[0056] like Figure 1 and Figure 2As shown, a long-distance absolute position measurement device based on the magnetic induction principle proposed by the present invention includes a magnetic marker 1, a magnetic induction displacement sensor 2, a signal conversion module 3 and a signal acquisition module 5. Several magnetic markers 1 are moved along the motion trajectory of the mobile device (i.e. Figure 1 The dotted lines in the figure) are arranged in sequence and remain fixed. A magnetic induction displacement sensor 2 is fixedly installed at the bottom of the mobile device and moves with the mobile device; the magnetic induction displacement sensor can simultaneously sense the magnetic field of each magnetic mark in the measurement range through the magnetostrictive effect and its inverse effect, realize non-contact sensing, and characterize the position of each magnetic mark through a pulse signal through the electronic unit module inside the sensor. The magnetic induction displacement sensor can respectively measure the pulse signal of each magnetic mark within the sensor range relative to the sensor electronic warehouse, and transmit the pulse signal to the signal conversion module. The magnetic induction displacement sensor 2 is connected to the signal conversion module 3 through a connecting cable 4, and the signal conversion module 3 is connected to the signal acquisition module 5. The signal conversion module 3 and the signal acquisition module 5 are both installed in the mobile device. The magnetic induction displacement sensor 2, the signal conversion module 3 and the signal acquisition module 5 constitute a magnetic induction signal acquisition system. The signal conversion module 3 obtains the distance information based on the time difference between the magnetic mark pulse waveform 21 and the starting pulse output by the magnetic induction displacement sensor 2 and multiplies it by the wave propagation speed, and calculates the spacing between each magnetic mark based on this, thereby calculating the real-time absolute position of the magnetic induction displacement sensor 2 relative to the magnetic mark, and outputs it to the mobile device data acquisition module 5, thereby forming a long-range absolute position positioning system.

[0057] The lift-off height of the magnetic induction displacement sensor 2 is between 12 and 58 mm, and the lateral deviation distance of the magnetic induction displacement sensor 2 is ±40 mm.

[0058] N magnetic marks 1 are arranged at intervals and form an interval coding component, N≥3; in each interval coding component, the distance between the N magnetic marks 1 forms a unique coding sequence, that is, different interval coding components correspond to different coding sequences, meeting the uniqueness requirement; in two adjacent interval coding components, the distance between the first magnetic mark 1 of the latter interval coding component and the last magnetic mark 1 of the previous interval coding component is set to a fixed value, that is, each interval coding component contains interval code and position code.

[0059] The sensing range of the magnetic induction displacement sensor 2 covers at least N+1 magnetic marks 1. In this embodiment, N=3, and the sensing range of the magnetic induction displacement sensor 2 covers at least 4 or more magnetic marks 1. As shown in Table 1, the interval coding is 400mm, and the other two variable intervals are position coding. The magnetic induction displacement sensor can detect 4 magnetic marks at each moment, that is, 3 magnetic mark intervals, and the 3 magnetic mark intervals include two parts: interval coding and position coding.

[0060] The coding table of the magnetic mark 1 is to first arrange the magnetic mark 1 according to the coding, and then measure the spacing of each magnetic mark 1 through the learning mode of the signal conversion module 3, so as to obtain the coding information actually arranged on site, form a set of one-dimensional coding tables, and save them in the EEROM data storage unit of the signal conversion module 3. The coding table is shown in Table 1.

[0061] Table 1 is a sample table of magnetic code arrangement according to an embodiment of the present invention.

[0062]

[0063]

[0064] When the magnetic induction displacement sensor 2 moves to cover the n+1th to n+4th magnetic scales 1, the magnetic induction displacement sensor 2 can convert each magnetic scale 1 within its detection range into an electrical pulse signal 21, and the electrical pulse signal 21 includes a start pulse 211 and a magnetic scale pulse 212. The signal conversion module 3 calculates the time difference t between the magnetic scale pulse 212 of each magnetic scale and the start pulse 211. 1 ,t 2 ,t 3 ,t 4 , respectively, and multiplied by the waveguide propagation speed c to obtain the distance information, and based on this, the distance c (t j+1 -t j ).

[0065] When there are less than N+1 magnetic marks 1 within the sensing range of the magnetic induction displacement sensor 2 or the offset distance of the magnetic mark 1 exceeds the preset offset threshold, the system can still work normally, and the signal conversion module 3 sends a warning signal and transmits it to the warning module, which needs to be processed in time.

[0066] Finally, it should be noted that the above embodiments and explanations are only used to illustrate the technical solution of the present invention rather than to limit it. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope disclosed in the technical solution of the present invention, which should be included in the scope of protection of the claims of the present invention.

Claims

1. A long-distance absolute position measurement method based on the principle of magnetic induction, characterized in that: The following steps are involved: Step 1: construct a reference absolute position coding table, wherein the reference absolute position coding table includes interval coding and position coding; Step 2: According to the reference absolute position encoding table, the magnetic markers (1) are arranged in sequence along the motion trajectory of the mobile device, and the actual arrangement spacing of the magnetic markers (1) is calibrated, so as to obtain the actual absolute position encoding table; Step 3: using a magnetic induction signal acquisition system installed in the mobile device to obtain a pulse signal of the magnetic marker (1) below the mobile device; Step 4: Selecting the incremental mode or the absolute mode according to the number of pulse signals of the magnetic marker (1) obtained; Step 5: Based on the actual absolute position encoding table, the validity of the pulse signal of the acquired magnetic mark (1) is judged, and then the position information of the mobile device is calculated and output to complete the position measurement.

2. The long-distance absolute position measurement method based on the magnetic induction principle according to claim 1 is characterized in that: The reference absolute position coding table contains multiple groups of different and unique coding sequences, each group of coding sequences includes an interval code and N-1 position codes, and multiple magnetic marks (1) corresponding to each group of coding sequences form an interval coding component; in two adjacent interval coding components, the distance between the first magnetic mark (1) of the latter interval coding component and the last magnetic mark (1) of the former interval coding component is set to a fixed value.

3. The long-distance absolute position measurement method based on the magnetic induction principle according to claim 1 is characterized in that: The motion trajectory of the mobile device is a straight line, a curve, or a trajectory combining a straight line and a curve.

4. The long-distance absolute position measurement method based on the magnetic induction principle according to claim 1 is characterized in that: The step 4 is specifically as follows: If the number of pulse signals of the magnetic marker (1) currently acquired is greater than or equal to N+1, the working mode of the magnetic induction signal acquisition system is the absolute mode; if the number of pulse signals of the magnetic marker (1) currently acquired is less than N+1, the working mode of the magnetic induction signal acquisition system is the incremental mode.

5. The long-distance absolute position measurement method based on the magnetic induction principle according to claim 1 is characterized in that: The step 5 is specifically as follows: When the incremental mode is selected, the real-time position information is calculated by comparing with the actual absolute position encoding table, and the warning information is output. When the absolute mode is selected, the validity of the pulse signal of the current magnetic mark (1) is determined by comparing it with the actual absolute position encoding table. If it is valid, the absolute position of the mobile device is calculated and output; if it is invalid, a new encoding sequence is generated according to the pulse signal of the current magnetic mark (1), and the new encoding sequence is stored in the actual absolute position encoding table and updated, thereby calculating and outputting the absolute position of the mobile device.

6. The long-distance absolute position measurement method based on the magnetic induction principle according to claim 5, characterized in that: The calculation and output of the absolute position of the mobile device is specifically as follows: First, the interval code and position code of the pulse signal of the currently acquired magnetic mark (1) are identified, and then the interval search is performed with the actual absolute position code table to obtain the matching interval code, and then the position code is compared with the matching interval code to obtain the absolute position of the mobile device.

7. A long-distance absolute position measurement device based on the principle of magnetic induction, characterized in that: The device comprises a magnetic marker (1), a magnetic induction displacement sensor (2), a signal conversion module (3) and a signal acquisition module (5); a plurality of magnetic markers (1) are arranged in sequence at intervals along the motion track of a mobile device; a magnetic induction displacement sensor (2) is fixedly mounted on the bottom of the mobile device; the magnetic induction displacement sensor (2) is connected to the signal conversion module (3); and the signal conversion module (3) is connected to the signal acquisition module (5).

8. The long-distance absolute position measurement device based on the magnetic induction principle according to claim 7, characterized in that: N magnetic marks (1) are arranged in a continuous interval and form an interval coding component, N≥3; in each interval coding component, the distance between the N magnetic marks (1) forms a unique coding sequence; in two adjacent interval coding components, the distance between the first magnetic mark (1) of the latter interval coding component and the last magnetic mark (1) of the former interval coding component is set to a fixed value.

9. The long-distance absolute position measurement device based on the magnetic induction principle according to claim 8, characterized in that: The sensing range of the magnetic induction displacement sensor (2) covers at least N+1 magnetic marks (1).

10. The long-distance absolute position measurement device based on the magnetic induction principle according to claim 9, characterized in that: When there are fewer than N+1 magnetic marks (1) within the sensing range of the magnetic induction displacement sensor (2) or the offset distance of the magnetic mark (1) exceeds a preset offset threshold, the signal conversion module (3) sends out an early warning signal and transmits it to the early warning module.

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