Internet of Things inspection system and method for photoelectric direct-reading water meter counter

Abstract

The invention discloses an Internet of Things inspection system and method for a photoelectric direct-reading water meter counter. The system comprises a multifunctional inspection device, an Internet of Things gateway and a manufacturing execution system MES. The invention provides a brand-new inspection thought, and the basic thought of the inspection thought is derived from'exhaustion test 'and'boundary test' in a digital circuit. Through the design of a detection structure device, all character wheels are forced to be axially linked, so that the character wheels are used as a whole to synchronously rotate, and all character wheel numbers in the counter are traversed by using an extremely short physical stroke; in combination with boundary overturning tests of all character wheels, namely all '9' and all '0', completeness verification of photoelectric direct reading and forward / backward logic of the counter can be completed in a short time. The method greatly improves the certainty and efficiency of inspection, constructs a full life cycle quality data tracing system, uploads the most critical inspection original photoelectric coding data in the production process to the MES in real time through the Internet of Things technology, and is in one-to-one correspondence with the unique code of the product and permanently bound with the unique code of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water meter manufacturing and quality detection, and particularly relates to an Internet of Things inspection system and method for a photoelectric direct-reading water meter counter. BACKGROUND

[0002] Photoelectric direct-reading water meters are widely used due to their stable and accurate readings and convenience for remote reading. The core component of the photoelectric direct-reading counter converts the rotating position of the number wheel into an optical signal through the cooperation of optical devices (such as light guide sheets) and reading number wheels, and then the printed circuit board assembly (PCBA) interprets it as a one-to-one corresponding digital reading. However, during the manufacturing process, the assembly quality of the optical devices, the light guiding performance, and the interpretation accuracy of the PCBA all affect the reliability of the final product.

[0003] Currently, the inspection of photoelectric direct-reading water meter counters is mostly carried out after the final assembly of the product.

[0004] The traditional inspection method mainly relies on camera image recognition or simulated pulse accumulation result comparison. The former is expensive, requires high light environment and clean number wheels, and is low in efficiency. The latter simulates the generation of pulses by driving the number wheel to rotate, and compares the accumulated results with the water reading. In practice, it is impossible to exhaust all possible code states (6-bit indicating water meter has 10 6 =1,000,000 states), and dynamic sampling inspection obviously has the risk of missing detection, and the test cycle is long, which cannot detect the error codes in the middle state.

[0005] Therefore, the existing technology lacks a systematic solution that can perform high-reliability inspection of photoelectric direct-reading water meter counters on the production line, associate detailed inspection data with the unique identity of the product, and realize full-process quality traceability. SUMMARY

[0006] The technical problem to be solved by the present application is to provide an Internet of Things inspection system and method for a photoelectric direct-reading water meter counter. The system creatively realizes various high-precision detections by cooperating the engagement or disengagement of the four-eight toothed wheels and the number wheels in the counter with the driving module, and realizes full-range and high-efficiency testing of the counter from photoelectric logic to mechanical precision.

[0007] The present application adopts the following technical solutions: An Internet of Things inspection system for a photoelectric direct-reading water meter counter, comprising: At least one multifunctional inspection device for performing full-state traversal testing and number wheel carry error code testing on the inspected photoelectric direct-reading counter of the water meter; An IoT gateway, which is communicatively connected to the multifunctional testing device, is used to collect testing data and upload it via a wireless network. The Manufacturing Execution System (MES) is used to receive and store inspection data from the Internet of Things (IoT) gateway, and to bind and associate the data with the unique code of the corresponding inspected counter. The multifunctional testing device includes: Inspection stand, used to position and support the object being inspected; The drive module is connected to the drive shaft of the photoelectric direct-read counter being tested or the lowest-position character wheel in the character wheel group, and is used to drive its stepping rotation; A communication interface is used to connect to the circuit board of the photoelectric direct-read counter under test, so as to provide optical excitation signals and receive photoelectric encoded data fed back from it; The control unit is electrically connected to the drive module and the communication interface, respectively, and is used to control the test process and receive and process photoelectric encoded data.

[0008] The system can implement at least two detection modes: Mode 1: Full state traversal and photoelectric logic verification ensure that all four-eight gears are disengaged from the corresponding gears in the gear group, and all gear values ​​are linked in the same rotation direction; the drive module drives the linked gear group to rotate synchronously one revolution, and the control unit reads and verifies the encoding correctness when traversing the number combinations of "000000", "111111"... "999999" through the communication interface; Mode 2: For the digit wheel group displaying a value of "999999" moving to "000000" or "000000" moving back to "999999", the accuracy of the carry / reload logic and error / missing code detection are performed. The linkage of all digit wheels is released, and all four-eight gears are engaged with their corresponding digit wheels. In the "000000" state, the drive module drives the unit digit wheel in the digit wheel group to rotate one revolution in the opposite direction. The control unit reads and verifies the unit digit wheel's rotation from "0" to "9" via the communication interface. The uniformity and continuity of the angular velocity of each character wheel during the transition from "0" to "9" is monitored. Then, the unit character wheel is rotated one revolution in the positive direction based on the "999999" indication state of the character wheel group. Similarly, the control unit reads and verifies the uniformity and continuity of the angular velocity of each character wheel during the transition from "999999" to "000000" through the communication interface, in order to monitor the accuracy of each character wheel's carry or back and the phenomenon of skipped or missing characters.

[0009] In the full-state traversal test, the control unit pre-stores the expected encoding sequence from "000000" to "999999", and compares in real time whether the value corresponding to the expected encoding sequence of the current sampling point is consistent with the photoelectric encoded data obtained by decoding. In the accuracy of the carry / retract logic and error code detection of the character wheel group, the control unit pre-stores the angular velocity value of the drive module driving the unit character wheel to rotate, and compares in real time whether the angular velocity corresponding to each 36° rotation of the unit character wheel obtained by decoding is consistent with the expected value of the current sampling point.

[0010] The drive module is a precision stepper motor, whose step angle resolution is less than one-tenth of the digital division angle of the character wheel.

[0011] The inspection stand includes a tray for placing counter standard parts. The tray is mounted on a base on both sides by elastic support plates. A pressure plate that can be pressed down electrically or pneumatically is provided above the tray, so that the light guide assembly and the light emitting / receiving circuit board can be reliably photoelectrically connected during inspection.

[0012] The IoT gateway uses LPWAN communication technology, including one or more of NB-IoT, Cat1, LoRaWAN, and WIoTa, to interact with the Manufacturing Execution System (MES). The IoT gateway also has Bluetooth broadcast communication capabilities, enabling it to interact with the inspection counters within its communication coverage area.

[0013] The Manufacturing Execution System (MES) establishes a quality file for each unique code corresponding to the photoelectric direct-reading water meter counter. The quality file records the following: photoelectric direct-reading data, comparison results, and full-process inspection data within the inspection period, to support quality traceability and defect analysis.

[0014] The inspection method based on the IoT inspection system of the present invention includes the following steps: S1: Loading and Configuration: Place the object to be inspected, which includes a light guide component, a light emitting / receiving circuit board for a photoelectric direct-reading water meter, or a counter with a unique code, on the inspection bench and connect the communication interface; according to the current inspection mode, mechanically configure the digit wheel group in counter 1 by removing or engaging the four-eight toothed wheel; S2: Execution detection: Control the drive module to run according to the preset mode; S3: Logic Determination: The control unit compares the acquired data with the expected logic of the current detection mode to determine whether the inspected item is qualified. S4: Data Upload and Binding: The test result data packet is uploaded to the Manufacturing Execution System (MES) via the IoT gateway for binding and storage. The test result data packet must include at least the product's unique code, test mode type, original photoelectric coding data, judgment conclusion, and timestamp.

[0015] The communication interface uses asynchronous serial port, SPI or I²C protocol to transmit word wheel encoded data; the inspection result data packet is transmitted from the inspection device to the IoT gateway via industrial Ethernet or RS-485 bus, and then uploaded to the Manufacturing Execution System (MES) via NB-IoT, Cat1 or other LPWAN networks.

[0016] The beneficial effects of this invention are: This invention proposes a novel verification approach, its basic idea derived from the "exhaustive testing" and "boundary testing" in digital circuits. Through the design of the detection structure, all digit wheels are forced to rotate axially in unison, making them rotate synchronously as a whole. This allows for the traversal of all digit wheel numbers in the counter with an extremely short physical travel (equivalent to the rotation time of one digit wheel for 360°). Combined with boundary flipping tests where each digit wheel is either all "9"s or all "0", the completeness verification of the counter's photoelectric direct reading and carry / borrow logic can be completed in a short time. This method transforms the verification problem from "dynamic value comparison" to "static logic verification," greatly improving the certainty and efficiency of the verification. It also possesses the following characteristics: 1. A pioneering multi-dimensional testing method using 4x8 gears as the testing medium: By actively manipulating their meshing state, it achieves integrated testing of photoelectric logic, carry function, single-tooth mechanical precision, and missing code, resulting in a high degree of functional integration.

[0017] 2. Achieve true full-state coverage: Through the “character wheel linkage” design, the massive number of combination tests are transformed into linear traversal, completing 100% coverage of millions of states in seconds. It can detect fixed coding errors of each character wheel on each number, which is unmatched by sampling inspection and completely eliminates sampling omissions.

[0018] 3. Construct a full lifecycle quality data traceability system: Through IoT technology, the most critical original photoelectric encoded data of the production process is uploaded to the MES in real time and permanently bound to the product's unique code. Any product can be quickly traced back to its entire production and inspection record, providing strong data support for quality analysis, precise defect location, process improvement, and accountability for after-sales issues.

[0019] 4. High System Flexibility and Scalability: Based on modular design, the multi-functional inspection device can be flexibly adjusted according to product models. Adopting the LPWAN IoT architecture, it facilitates flexible deployment and expansion of inspection stations within the production workshop. Deep integration of the IoT system with MES integrates inspection data into the enterprise's big data pool, supporting advanced manufacturing transformation and upgrading. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall architecture of the Internet of Things system of the present invention.

[0021] Figure 2 This is a schematic diagram showing the placement of counters when using a multi-functional testing device to inspect the encoding of an optical guide component.

[0022] Figure 3 for Figure 2 A schematic diagram showing the separation of the counter, photoconductor assembly, and optical transmitter / receiver circuit board.

[0023] Figure 4 This diagram illustrates the placement of the counter when using a multi-functional testing device to check the accuracy of the carry / reload logic of the character wheel group and to detect missing codes.

[0024] Figure 5 for Figure 4 A schematic diagram showing the separation of the counter, photoconductor assembly, and optical transmitter / receiver circuit board.

[0025] Figure 6 for Figure 5 An explosion diagram.

[0026] Figure 7 This is a flowchart of the steps involved in verifying the method.

[0027] Reference numerals in the attached diagram: 1. Counter; 2. Upper clamping plate; 3. Lower clamping plate; 4. Number wheel assembly; 5. Four-eight toothed wheel; 6. Direct reading window hole; 7. Guide plate hole; 8. Gear transmission assembly; 9. Light guide assembly; 10. Light guide plate; 11. Light emitting / receiving circuit board; 12. Stepper motor; 13. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only for illustrating the technical solutions of the present invention, and not for limiting it.

[0029] like Figure 1 As shown, the IoT inspection system for a photoelectric direct-reading water meter counter 1 provided by this invention consists of several multi-functional inspection devices deployed in the production workshop (multiple functional inspection devices can be set on a rotatable, semi-automatic circular operating platform), an IoT gateway in the workshop, and a factory-level Manufacturing Execution System (MES, hereinafter referred to as the MES system or MES server). The multi-functional inspection devices are connected to the local IoT gateway through an industrial Ethernet switch. The IoT gateway communicates with the operator's base station through NB-IoT or other LPWAN networks, transmitting data via the Internet to the enterprise's internal MES server located in the cloud.

[0030] 1. Optical guide assembly 9 The light guide assembly 9 of the present invention consists of a plurality of light guide sheets 10 (also called light guide plates) arranged side by side and spaced apart. Each light guide sheet 10 is a light emitting light guide sheet 10 and a light receiving light guide sheet 10. The light emitting light guide sheet 10 and the light receiving light guide sheet 10 are arranged adjacent to each other. These light guide sheets 10 are centrally mounted and fixed to a light guide base 11. During assembly, the plurality of light guide sheets 10 in the light guide assembly 9 are installed by inserting each individual light guide sheet 10 between two adjacent number wheels in the number wheel assembly 4. The light guide base 11 is mounted on a light emitting / receiving circuit board that is electrically connected to the water meter circuit board (see [link]). Figure 6 (As shown).

[0031] For the specific structure of the optical guide component 9 of the present invention, the cooperation between the optical guide component 9 and the digit wheel group 4, and the working principle of obtaining the digit wheel reading, please refer to the patent application number: 201910396448.2, entitled: Signal transmission structure and direct reading water meter for collecting water metering values ​​in a sealed cavity, and publication number: CN 110017879 A.

[0032] The encoding settings on each wheel in the digit group 4 of the water meter counter 1 of the present invention are described in the patent application number 2008101416803, entitled "Meter Counter Remote Direct Reading Encoder", and published in CN 101319918 A. The "carry-coupling wheel" in the patent document is the "four-eight toothed wheel 5" described in the present invention.

[0033] 2. Multifunctional testing device The multi-functional inspection device includes an inspection stand (not shown in the figure), on which a base is provided, and on which a tray is provided. The tray has the following two uses: The first type is a counter 1 used for positioning and supporting standard parts. The counter 1 includes a gear transmission assembly 8 installed between the upper clamping plate 2 and the lower clamping plate 3 and a standard part of a direct-reading character wheel group 4 (preferably 6 character wheels, namely the ones, tens, ... hundred thousand character wheels).

[0034] The counter 1 can be fixed on the tray by a clamp or by setting a positioning recess on the top surface of the tray to fit the counter 1.

[0035] The second type is used to position and support the light guide assembly 9 and / or the light emitting / receiving circuit board 12 of the standard component. Similarly, a positioning recess is provided on the top surface of the tray to accommodate the light guide seat 11 in the light guide assembly 9 or the light emitting / receiving circuit board 12.

[0036] This multi-functional testing device can perform the following testing functions (see...) Figure 7 (As shown in the flowchart) 1) Inspect the optical guide assembly 9 to be assembled (using the first type of tray mentioned above).

[0037] a. The counter 1 with standard components (all four-eight gears 5 are removed, and all character wheels are synchronously linked in the rotational direction, spaced apart and relatively fixed in the axial direction; hereinafter, this linked character wheel group 4 is referred to as the linked character wheel group 4, and each character wheel in the linked character wheel group 4 is a standard component) is positioned on the tray with the guide plate hole 7 (referring to the hole on the bottom surface of the counter 1 where the light guide plate 10 is inserted into the character wheel group 4) facing upwards (see...). Figure 2 , Figure 3 As shown, this method involves placing the counter 1 face down. In this case, all the digits in the digit wheel group 4 will display the same value, such as setting the value of the six-digit digit wheel to "000000".

[0038] b. The light guide assembly 9 to be tested is positioned on the number wheel assembly 4 by inserting the light guide plate 10 into the corresponding guide plate hole 7 from top to bottom. Then, the light emitting / receiving circuit board 12 of the standard part is positioned and pressed against the light guide seat 11 of the light guide assembly 9, so that the light guide plate 10 and the light emitting / receiving circuit board 12 are photoelectrically connected, and the light emitting / receiving circuit is connected to the water meter control circuit.

[0039] c. The stepper motor 13 (also called the drive module), mounted on the counter 1 or base, is activated to drive the linked digit wheel group 4 to rotate, performing a full state traversal and photoelectric logic verification (detecting "error codes"). The drive module drives the digit wheel group 4 to rotate synchronously one full revolution (physical 360°), which is equivalent to traversing all million-level digit combinations from "000000", "111111"..."999999". The control unit reads the code at each position through the photoelectric interface, compares it with the correct sequence pre-stored in the control circuit, and the control circuit displays the photoelectric logic verification information on the display screen of the multi-functional verification device. It can efficiently complete a full-coverage photoelectric logic test to verify the correctness of the codes output by each light guide sheet 10.

[0040] When the comparison results are different, it indicates that the coding of the light guide component 9 is incorrect, and the control circuit will issue an alarm signal in the form of sound and light.

[0041] 2) Inspect the light emitting / receiving circuit board 12 to be assembled (using the first type of tray mentioned above).

[0042] a. The counter 1 with standard components (all four-eight gears 5 are removed, and all character wheels are synchronously linked in the rotational direction, spaced apart and relatively fixed in the axial direction; hereinafter, this linked character wheel group 4 is referred to as the linked character wheel group 4, and each character wheel in the linked character wheel group 4 is a standard component) is positioned on the tray with the guide plate hole 7 (referring to the hole on the bottom surface of the counter 1 where the light guide plate 10 is inserted into the character wheel group 4) facing upwards (see...). Figure 2 , Figure 3As shown, this method involves placing the counter 1 face down. In this case, all the digits in the digit wheel group 4 will display the same value, such as setting the value of the six-digit digit wheel to "000000".

[0043] b. Insert the standard light guide assembly 9 into the corresponding guide hole 7 with the light guide plate 10 from top to bottom and place it on the number wheel group 4. Then, press the light emitting / receiving circuit board 12 to be tested against the light guide seat 11 of the light guide assembly 9, so that the light guide plate 10 and the light emitting / receiving circuit board 12 are photoelectrically connected, and the light emitting / receiving circuit is connected to the water meter control circuit.

[0044] c. The stepper motor 13 (also called the drive module), mounted on counter 1 or the base, is activated to drive the linked digit wheel group 4 to rotate, performing a full state traversal and photoelectric logic verification (detecting "error codes"). The drive module drives the digit wheel group 4 to rotate synchronously one full revolution (physical 360°), which is equivalent to traversing all million-level digit combinations from "000000", "111111"..."999999". The control unit reads the code of each position through the photoelectric interface and compares it with the correct sequence pre-stored in the control circuit. The control circuit then displays the photoelectric logic verification information on the display screen of the multi-functional verification device. It can efficiently complete a full-coverage photoelectric logic test to verify the quality of the light emitting / receiving circuit board 12.

[0045] When the comparison results are different, it indicates that there is a signal transmission error in the light emitting / receiving circuit board 12, and the control circuit will issue an alarm signal in the form of sound and light.

[0046] 3) Accuracy of carry / borrow logic and detection of missing codes for all "9" to all "0" and all "0" to all "9" in character wheel group 4 (using the second type of tray mentioned above).

[0047] a. Install the standard light emitting / receiving circuit board 12, which is electrically connected to the control circuit, on the tray, and then assemble the standard light guide assembly 9 on the light emitting / receiving circuit board 12 to make them photoelectrically connected. At this time, each light guide sheet 10 in the light guide assembly 9 points upward.

[0048] b. Position the counter to be tested 1 (which includes the gear transmission assembly 8, the number wheel group 4, and the four-eight-tooth gears 5, all of which are normally meshed with their corresponding number wheels) with the direct reading window 6 of the counter 1 facing upwards (i.e., the counter 1 panel is facing upwards, see...). Figure 4 , Figure 5 As shown, the light guide assembly 9 is fixedly mounted on the light guide component 9. At this time, each light guide sheet 10 in the light guide component 9 is inserted into the corresponding guide sheet hole 7 from bottom to top. Then, the values ​​of all the digit wheels in the digit wheel group 4 are set to "0", such as setting the value of the six-digit digit wheel group 4 to "000000".

[0049] c. The drive module drives the units digit wheel in wheel group 4 to rotate one revolution in the reverse direction. The control unit reads and verifies the uniformity and continuity of the angular velocity of each wheel during the process of the units digit wheel flipping from "0" to "9" and causing the higher digit wheels to regress from "0" to "9" via the communication interface. Then, the units digit wheel in wheel group 4 rotates one revolution in the forward direction based on the "999999" indication. Similarly, the control unit reads and verifies the uniformity and continuity of the angular velocity of each wheel during the process of the wheel flipping from "999999" to "000000" via the communication interface. It also compares in real time whether the angular velocity corresponding to each 36° rotation of the units digit wheel obtained from decoding is consistent with the correct angular velocity and continuity requirements pre-stored in the control circuit at the current sampling point, in order to monitor the accuracy of carry or regression of each wheel and the phenomenon of skipped or missing characters. The control circuit displays the photoelectric logic verification information on the display screen of this multi-functional verification device.

[0050] When the comparison results show a large discrepancy, the control circuit will issue an alarm signal in the form of sound and light.

[0051] II. Core Verification Logic of this Invention 1. Full-element function test (traversal test): Since all components of counter 1 are injection molded in one piece, the consistency of form and position tolerances within the allowable range is excellent. During the full-state traversal test, the four-eight toothed gear 5 for the digit wheel advance can be removed, and the six digit wheels of counter 1 can be axially bonded and linked to form a whole "digit wheel group 4". The digit wheel group 4 is driven to rotate continuously and uniformly starting from the "000000" position. Ideally, every time the digit wheel group 4 rotates 36° (360° / 10), the apparent number of all digit wheels increases by 1 synchronously, with the states sequentially as follows: 000000→111111→222222→...→999999. During this process, the main board of counter 1 (i.e., the control circuit) continuously reads and decodes the signal from the photoelectric sensor. The test system has pre-stored expected encoded values ​​from "000000" to "999999", and the system compares the decoded values ​​with these values ​​in real time. If the decoded value does not match the current six identical digits (for example, the value of character wheel group 4 is "444444", while the decoded value is "445444"), it is immediately judged as unqualified. This process can check whether each character wheel, the light-emitting tube (i.e., the light emitting circuit), the light guide plate (i.e., the light guide sheet 10), and the receiving tube (i.e., the light receiving circuit) corresponding to each number are working properly and whether there are any encoding errors.

[0052] The above situation can be used to check whether the working quality and reliability of the light-emitting diode, light guide plate, receiver tube and circuit are normal when the character wheel group 4 of counter 1 is a standard component. It can also be used to check whether the encoding of each character wheel in character wheel group 4 is correct when the light-emitting diode, light guide plate, receiver tube and circuit are standard components.

[0053] 2. Carry logic accuracy test (boundary test): The initial state of counter 1 upon arrival is "000000". The test starts from the "000000" state, driving the lowest digit wheel to rotate continuously in the opposite direction. Observe whether its flip from "0" to "9" can reliably drive the tens digit wheel from "0" to "9", which may then trigger a chain reaction of shifting to the hundreds, thousands, etc. The reverse direction can be used to perform a carry test from "999999" to "000000". As long as all the higher digit wheels can accurately link according to the flip of the lower digit at the two critical points of "9→0" and "0→9", it can be proved that the mechanical carry mechanism of counter 1 is functioning properly.

[0054] 3. The core of the inspection process The core of the verification is to confirm the absolute correctness of the following three key aspects: ① Mechanical linkage: Can all the number wheels rotate synchronously and smoothly under the drive of the stepper motor 13 of the inspection table, without jamming or tooth slippage?

[0055] ② Photoelectric response integrity: Whether each pair of transmitter / receiver tubes corresponding to each character wheel can respond correctly (conduct or cut off) at all positions (0-9) of the character wheel.

[0056] ③ Correctness of carry logic: When the lower-order word wheel flips from 9 to 0 (or from 0 to 9), can it accurately trigger the carry (or borrow) action of the adjacent higher-order word?

[0057] Starting from the production inspection elements, once the above three links are implemented, the completeness of the incoming material inspection of the light guide component 9, counter 1, counter 1 motherboard, and finished product inspection of the photoelectric direct-read counter 1 can be achieved.

[0058] 4. System Composition The inspection system mainly consists of a drive module, an electrical control module, and a test and judgment module. The working logic flowchart of the inspection system is as follows: Figure 7 As shown: ①Drive module: including high-precision stepper motor 13, axially bonded character wheel group 4 during traversal testing, and counter 1 whose original state is "000000" during boundary testing.

[0059] ② Electrical control module: Powers the counter 1 control board and reads the output signal of the photoelectric direct-reading sensor.

[0060] ③ Test and Judgment Module: This is an embedded dedicated test fixture that internally stores a standard encoding table and control logic, and performs real-time comparison and judgment.

[0061] 5. Theoretical Model and Probability Analysis of the Testing Process 5.1 State-Time Model Assume that counter 1 has n word wheels (n=6 in this example), and each word wheel has m states (m=10, with values ​​from 0 to 9). In traditional sampling inspection, we assume that k states are sampled with equal probability.

[0062] ① Linked traversal test: This method essentially combines m n Each state is "compressed" into an equivalent state chain of length m: S0(000000)→S1(111111)→…→Sm-1(999999). One rotation of the character wheel group 4 corresponds to m physical steps. If the sampling time for each step is Δt, then the total test time T… full =m*Δt. When m=10, Δt=100ms, T full =1s, meaning all 10 can be completed within 1 second. 6 Traversal of each logical state.

[0063] ② Traditional dynamic testing: To traverse the 10 states of a single character wheel, it needs to rotate at least one revolution. For a 6-digit independent character wheel, to cover all combinations, theoretically, the lower-digit character wheel needs to be driven to rotate 10 revolutions. 6 A loop is clearly impractical in production. Monte Carlo simulation is typically used, randomly testing k states, which takes time T. sample =k*Δt', where Δt' includes the waiting time for the character wheel to rotate to the "visible position", and this value is much greater than Δt.

[0064] Conclusion: The linked traversal method has an overwhelming advantage in time efficiency and achieves 100% state coverage.

[0065] 5.2 Error and Omission Code Defect Model and Probability Calculation The drawbacks of defining counter 1: ①Sticky Error: When a certain number wheel is in a specific number d, its photoelectric encoding output is always the error code e.

[0066] ②Random Error: When a certain number d is given, the encoded output of a certain character wheel is incorrect with probability p.

[0067] ③ Skip Error: During the rotation of the number wheel, a certain number is skipped with probability q, and the encoded output jumps directly from d to d+2.

[0068] 5.2.1 Analysis of the detection capability of linked traversal test ① Detection probability of fixed error codes: The linked traversal test covers 100% of every digit in each wheel. Therefore, for any fixed error code, when the test reaches this defective state, the decoded output will inevitably differ from the expected value (e.g., "555555"), and will be detected immediately. The detection probability P detect_fixed =1.

[0069] ② Detection probability of random errors: Suppose a single character wheel has a random error occurring on a single digit position each time it is queried, and the probability is p. In the linked traversal test, the defective digit position is accessed only once, so the probability of misjudgment due to this defect is p, and the probability of the test failing to detect it is 1-p. Since the test covers all digits, the probability of missed detection for each potential defect position is P. miss_random =1−p, but the system design can reduce the false negative rate by performing multiple (e.g., N) sampling queries at each state point. Assuming each sampling is independent, after N samplings, the false negative rate drops to (1−p). N When p=0.1 and N=5, P miss =0.9 5 ≈0.59; when N=20, P miss ≈0.12. The risk of missed detection can be controlled within an acceptable range by increasing the number of samplings N.

[0070] ③ Ability to detect missing codes: Linked traversal test cannot directly detect missing codes because the character wheel is forcibly linked, and there is no physical possibility of skipping a certain position. Missing code detection must rely on carry boundary test or traditional dynamic test.

[0071] 5.2.2 Detection capability analysis of carry boundary test Carry boundary testing primarily targets defects in gear carry mechanisms and number wheel positioning mechanisms, focusing on testing the two most critical transitions: "9→0" and "0→9". Assume the carry system has the following defects: ① Carry failure: When the lower bit is "9→0", the probability that a "1" cannot be carried over to the higher bit is p. carry .

[0072] ② Carry jitter: When the lower bit changes from "9" to "0", the higher bit will produce an uncertain jump that is not "1".

[0073] In boundary testing, we actively perform a carry operation from "all 9s to all 0s". Ideally, the least significant bit changes from 9 to 0, and the carry drives all the higher significant bits to change from 9 to 0 in sequence, creating a chain reaction. Assume that the probability of each carry succeeding is independent and 1-p. carryFor a 6-bit counter 1 to carry from "999999" to "000000", it requires 5 consecutive carry operations (ones digit → tens digit → hundreds digit → thousands digit → ten thousands digit → hundred thousands digit). Therefore, the probability that a successful boundary test proves all 5 carry operations are correct is (1-p). carry ) 5 In other words, as long as p carry >0, a single test can achieve a fairly high probability [1-(1-p] carry ) 5 This exposes a carry problem. The probability of a false negative during the entire carry system test is: p miss_carry ={1-[1-(1-p carry ) 5 ]} M ≈[(1-p carry ) 5 ] M =(1-p carry ) 5M If the test is repeated multiple times (M times), this value decreases sharply as M increases.

[0074] 5.2.3 Overall Probability of Missed Detections Suppose a counter 1 may have multiple independent defects: random error probability p, carry failure probability p carry The probability of missing a random error in the linked traversal test is (1-p). N The probability of missing a carry failure in the boundary test is (1-p). carry ) 5M Therefore, the probability of incorrectly determining that the overall function of counter 1 is qualified by this method is approximately: p false_accept ≈(1-p) N *(1-p carry ) 5M This is a very conservative estimate because it ignores fixed errors and other unmodeled defects. By reasonably setting N and M (e.g., N=10, M=3), even for p=0.2, p carry A relatively high defect rate of 0.1 also exists: p false_accept ≈(0.8) 10 *(0.9) 15 ≈0.022 That is, the false negative rate is about 2.2%, while for a production line with stable quality, p and p carry Typically, the value is much lower than 0.01, at which point the probability of a missed detection can be reduced to less than 10. -6 Extremely low level.

[0075] Table 1. Overall false negative probability p under different parameters false_accept Estimate Single random error probability p Single carry failure probability p carry ]] Number of traversed samples N Number of boundary tests M false_accept ]]> ​ 0.10 0.05 5 2 0.354 0.10 0.05 10 3 0.162 0.05 0.02 10 3 0.443 0.01 0.01 10 3 0.777 0.20 0.10 20 5 8.6 x 10 -4 ]]> 0.01 0.005 20 5 0.721 Note: The calculations in the table show that for occasional defects (p, p) carry (The probability of a defect not occurring is relatively low). Simply increasing the number of single-state tests N and M has limited effect on reducing the missed detection rate because the probability of a defect not occurring is already high. This illustrates the extreme importance of the linked traversal method covering all states—it ensures that every fixed defect is captured. The high missed detection probability in the table mainly comes from the situation where random defects happen not to occur within the test window. In actual production, if the probability of random defects is very low, their harm is relatively small. The core value of this method lies in completely eliminating the missed detection of fixed defects.

[0076] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An Internet of Things (IoT) inspection system for photoelectric direct-reading water meter counters, characterized in that, include: At least one multi-functional testing device is used to perform a full-state traversal test and a number wheel carry-in error test on the tested photoelectric direct-reading counter (1) of the water meter; An IoT gateway, which is communicatively connected to the multifunctional testing device, is used to collect testing data and upload it via a wireless network. The Manufacturing Execution System (MES) is used to receive and store inspection data from the Internet of Things (IoT) gateway and bind the data with the unique code of the corresponding inspected counter (1). The multifunctional testing device includes: Inspection stand, used to position and support the object being inspected; The drive module is connected to the drive shaft of the photoelectric direct-read counter (1) under test or the lowest character wheel in the character wheel group (4) to drive its stepping rotation; A communication interface is provided for connecting the circuit board of the tested photoelectric direct-read counter (1) to provide a light excitation signal and receive the photoelectric encoded data fed back by it. The control unit is electrically connected to the drive module and the communication interface, respectively, and is used to control the test process and receive and process photoelectric encoded data.

2. The IoT inspection system for photoelectric direct-reading water meter counters according to claim 1, characterized in that, The system can implement at least two detection modes: Mode 1: Full state traversal and photoelectric logic verification ensure that all four-eight gears (5) are disengaged from the corresponding gears in the gear group (4), and all gear values ​​are linked in the same rotation direction; the drive module drives the linked gear group (4) to rotate synchronously one revolution, and the control unit reads and verifies the encoding correctness when traversing the combination of numbers "000000", "111111"... "999999" through the communication interface; Mode 2: For the value of the character wheel group (4) from "999999" to "000000" or from "000000" to "999999", the accuracy of the carry / retract logic and the detection of missing codes are checked. The linkage of all character wheels is released and all four-eight gears (5) are engaged with the corresponding character wheels. In the state of "000000", the drive module drives the unit character wheel in the character wheel group (4) to rotate one revolution in the opposite direction. The control unit reads and verifies the unit character wheel from "0" to "9" through the communication interface. The flip causes the high-position character wheel to change from "0" to "9" to ensure the uniformity and continuity of the angular velocity of each character wheel. Then, the unit character wheel is rotated one revolution in the positive direction by the "999999" indication state of the character wheel group (4). Similarly, the control unit reads and verifies the uniformity and continuity of the angular velocity of each character wheel during the flip from "999999" to "000000" through the communication interface, so as to monitor the accuracy of the carry or rollback of each character wheel and the phenomenon of skipped characters or missing codes.

3. The IoT inspection system for photoelectric direct-reading water meter counters according to claim 2, characterized in that, In the full-state traversal test, the control unit pre-stores the expected encoding sequence from "000000" to "999999", and compares in real time whether the photoelectric encoded data obtained by decoding is consistent with the value corresponding to the expected encoding sequence of the current sampling point; in the accuracy of the carry / retract logic and error code detection of the character wheel group (4), the control unit pre-stores the angular velocity value of the drive module driving the unit character wheel to rotate, and compares in real time whether the angular velocity corresponding to each 36° rotation of the unit character wheel obtained by decoding is consistent with the expected value of the current sampling point.

4. The IoT inspection system for photoelectric direct-reading water meter counters according to claim 1, characterized in that, The drive module is a precision stepper motor (13), whose stepping angle resolution is less than one-tenth of the digital division angle of the character wheel.

5. The IoT inspection system for photoelectric direct-reading water meter counters according to claim 2, characterized in that, The inspection stand includes a tray for placing the counter (1) standard parts. The tray is mounted on the base on both sides by elastic support plates. A pressure plate that can be pressed down electrically or pneumatically is provided above the tray, so that the light guide assembly (9) and the light emitting / receiving circuit board (12) can be reliably photoelectrically connected during inspection.

6. The IoT inspection system for photoelectric direct-reading water meter counters according to claim 1, characterized in that, The IoT gateway uses LPWan communication technology, including one or more of NB-IoT, Cat1, LoRaWan and WIoTa, to interact with the Manufacturing Execution System (MES); the IoT gateway also has Bluetooth broadcast communication function, which can interact with the inspection device (1) of the inspection counter within the communication coverage area.

7. The IoT inspection system for photoelectric direct-reading water meter counters according to claim 1, characterized in that, The Manufacturing Execution System (MES) establishes a quality file for each unique code corresponding to the photoelectric direct-reading water meter counter (1). The contents recorded in the quality file include: photoelectric direct-reading data, comparison results, and full-process inspection data within the inspection time, in order to support quality traceability and defect analysis.

8. An inspection method based on the Internet of Things (IoT) inspection system according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Loading and configuration: Place the object to be inspected, which includes the light guide component (9), the light emitting / receiving circuit board (12) of the photoelectric direct reading water meter, or the counter (1) with a unique code, on the inspection stand and connect the communication interface; according to the current inspection mode, mechanically configure the character wheel group (4) in the counter (1) by removing or engaging the four-eight toothed wheel (5); S2: Execution detection: Control the drive module to run according to the preset mode; S3: Logic Determination: The control unit compares the acquired data with the expected logic of the current detection mode to determine whether the inspected item is qualified. S4: Data Upload and Binding: The test result data packet is uploaded to the Manufacturing Execution System (MES) via the IoT gateway for binding and storage. The test result data packet must include at least the product's unique code, test mode type, original photoelectric coding data, judgment conclusion, and timestamp.

9. The inspection method of the Internet of Things inspection system according to claim 8, characterized in that, The communication interface uses asynchronous serial port, SPI or I²C protocol to transmit word wheel encoded data; the inspection result data packet is transmitted from the inspection device to the IoT gateway via industrial Ethernet or RS-485 bus, and then uploaded to the Manufacturing Execution System (MES) via NB-IoT, Cat1 or other LPWAN networks.

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