Cabinet door opening and closing state detection system based on RFID

Abstract

The invention relates to the technical field of Internet of Things perception, and discloses an RFID-based cabinet door opening and closing state detection system, which comprises an RFID tag, an RFID reader-writer and an antenna, respectively deploying an RFID tag and an antenna on a cabinet door and a cabinet body in the electrical cabinet, obtaining the received signal strength indication and phase of the reflected signal through an RFID reader-writer, and further analyzing the opening and closing state of the cabinet door of the electrical cabinet; every three RFID tags form a group to form an equilateral triangle, and the interval between any two RFID tags is set to be about one fourth of the wavelength of a reflected signal. Through a unique multi-label equilateral triangle deployment mode, the signal reflection problem caused by a metal material in the electrical cabinet can be solved, it is ensured that at least one label signal is stable and available, and the stability of the system and the signal reliability are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of Internet of Things sensing technology, and in particular to an RFID-based cabinet door switch state detection system. Background Art

[0002] Radio frequency identification (RFID) technology, as a wireless identification and data transmission technology, has extremely wide applications in the field of industrial automation, such as industrial electrical cabinet intelligent sensing and other industrial fields. In the existing technology, there are many applications that use RFID tags to achieve activity tracking, personnel positioning and environmental monitoring, thereby expanding the sensing capabilities of RFID.

[0003] However, in the field of industrial electrical, especially in the status supervision of distribution cabinets, there are still some urgent problems to be solved. As an important part of the power system, the operating status of the distribution cabinet is directly related to the safety and stability of the entire power system. The lack of fast and accurate status supervision of distribution cabinets will bring serious safety hazards. 60% of electrical fires are caused by poor daily maintenance, equipment operation with defects, and personnel illegal operations, most of which can be avoided through accurate equipment status monitoring. Existing traditional methods for monitoring the status of cabinet doors usually involve active sensors that require a constant power supply and are susceptible to mechanical wear. These problems have prompted the need for a more reliable and cost-effective solution. RFID has the characteristics of easy installation, low cost, maintenance-free, and long life, making it an ideal solution for continuous monitoring.

[0004] The present invention uses RFID technology to monitor the switch status of electrical cabinets in industrial scenarios to ensure their safety and operational integrity. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an RFID-based cabinet door switch status detection system, which senses the switch status of the electrical cabinet through the RFID system to achieve long-term continuous monitoring, thereby preventing electrical fires caused by unauthorized contact; and improves the safety of industrial production by realizing intelligent sensing in industrial production.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A cabinet door switch state detection system based on RFID analyzes the reflected signal of the RFID tag obtained by the RFID reader to obtain the switch state of the cabinet door of the electrical cabinet; the detection system comprises: an RFID tag, an RFID reader, and an antenna; the RFID tag and the antenna are respectively deployed on the cabinet door and the cabinet body in the electrical cabinet, and the received signal strength indication and phase of the reflected signal emitted by the RFID tag via the antenna are obtained by the RFID reader, so as to analyze the switch state of the cabinet door of the electrical cabinet; wherein, every three RFID tags form a group to form an equilateral triangle, and the interval between any two RFID tags is set to one quarter of the wavelength of the reflected signal.

[0008] Furthermore, it also includes an abnormal data processing process: abnormal data is processed by extracting the anti-interference characteristics of the equipment to prevent state estimation errors.

[0009] Furthermore, the processing of abnormal data by extracting the anti-interference characteristics of the device to prevent state estimation errors specifically includes:

[0010] The received signal strength indication and phase received at the tth time are collectively referred to as the observation value

[0011]

[0012] x t It represents the ideal value obtained without external interference at the tth moment;

[0013] in, is the cumulative deviation,

[0014] This patent extracts the anti-interference feature y from the accumulated deviation t and z t :

[0015]

[0016] in, is the historical observation value in the closed state; y t Represents the difference between the observed value at the tth moment and the historical observed value of the door closing state, to measure the distance between states; z t It represents the variance of the observed value from the lth moment to the tth moment, so as to determine whether there is fluctuation during this period; l represents the index of the lth moment.

[0017] Furthermore, the method of obtaining the received signal strength indication and phase of the reflected signal emitted by the RFID tag via the antenna through the RFID reader, and then analyzing the switch state of the door of the electrical cabinet, specifically includes:

[0018] The current switch state of the cabinet door is estimated based on the historical switch state of the cabinet door and the received signal strength indication and phase of the current and historical reflected signals.

[0019] Furthermore, the estimating the current switch state of the cabinet door according to the historical switch state of the cabinet door and the received signal strength indication and phase of the current and historical reflected signals specifically includes:

[0020] The open state of the cabinet door is defined as state "1", the closed state of the cabinet door is defined as state "0", the movement of the cabinet door is defined as state "2", and the abnormal data collected during monitoring is defined as state "3";

[0021] The exception handling process includes:

[0022] Judgment |y t+1 -y t |> Is δ true? If so, set S(t+1)=3; y t+1 and t represents the anti-interference feature at time t and time t+1, S(t+1)=3 means that the state at the current time, i.e., time t+1, is defined as state "3"; δ represents the anti-interference feature threshold of the exception handling process;

[0023] When S(t) = 3, search forward according to the historical state until a state S(i) other than state "3" and state "2" is found, and the state at time t+1 is defined as state S(i): S(t+1) = S(i);

[0024] State transfer process:

[0025] Judgement t >ε is true, if so, set S(t+1)=2, and set the state at time t+1 to state "2", indicating that the cabinet door is moving at this time; ε is the anti-interference threshold during the state transfer process;

[0026] When S(t) = 2, judge |y t+1 |> Is γ established? If so, set S(t+1)=1 and set the state at time t+1 to state "1"; if not, set S(t+1)=0 and set the state at time t+1 to state "0";

[0027] Keep state process:

[0028] Determine whether S(t)=0 is true:

[0029] If yes, update And let S(t+1)=0;

[0030] If not, determine whether S(t)=1 holds; if so, determine S(t+1)=1.

[0031] Compared with the prior art, the beneficial technical effects of the present invention are:

[0032] 1) Low cost, maintenance-free, and long life: Compared with traditional active sensors, the present invention uses RFID technology, has a simple hardware system, does not require an external power supply, and is maintenance-free, which can significantly reduce the operation and maintenance costs of the equipment. RFID tags have a long service life, reducing the additional costs and workload caused by frequent replacement of sensors.

[0033] 2) Stability and robustness: Through the unique multi-tag equilateral triangle deployment method, the present invention can overcome the signal reflection problem caused by metal materials in the electrical cabinet, ensure that at least one tag signal is stable and available, and significantly improve the stability and signal reliability of the system. The present invention adopts an anti-interference feature extraction algorithm, which can effectively reduce the influence of hardware noise and ensure the accuracy of equipment status monitoring due to lax quality control of the internal circuit of the RFID tag and interference caused by high-frequency reading.

[0034] 3) High-precision status monitoring: By accurately analyzing the received signal strength indication (RSSI) and phase (Phase) of the tag reflection signal, the present invention can accurately detect the switch status of the electrical cabinet door, ensuring that every state change can be captured in a timely and accurate manner. Based on the threshold method and state transition algorithm, the system combines historical data and real-time information to accurately estimate the switch status of the electrical cabinet door, avoiding false alarms or missed alarms caused by environmental interference or equipment failure in traditional methods.

[0035] 4) Long-term continuous perception capability: The present invention realizes continuous monitoring of the switch status of the electrical cabinet by designing a perception algorithm that can run stably for a long time. Compared with traditional solutions, the present invention can continuously monitor the equipment status around the clock without human intervention, ensuring the safe operation of the equipment.

[0036] 5) Easy to expand and integrate: RFID-based systems are compatible with existing IoT architectures and can be easily integrated into industrial automation and intelligent management systems. In practical applications, RFID systems can be linked with other sensor systems and monitoring platforms to achieve more extensive intelligent perception and data sharing, further improving industrial production safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic diagram of a detection system in an embodiment of the present invention;

[0038] Figure 2 Schematic diagram of the process of the long-term continuous sensing algorithm in the embodiment of the present invention;

[0039] Figure 3 The figure is a schematic diagram of the deployment of the hardware system in the embodiment of the present invention. DETAILED DESCRIPTION

[0040] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0041] The present invention focuses on analyzing the reflected signal of the RFID tag obtained by the RFID reader to obtain the switch status of the door of the electrical cabinet. Figure 1 As shown, the technical solution in the present invention mainly includes two parts, including hardware system setting and software algorithm processing.

[0042] The following is a detailed description of the technical solution:

[0043] 1. Hardware system settings:

[0044] The change of the relative position between the tag and the antenna will cause the change of the received signal strength indication (RSSI), so that there is a mapping relationship between RSSI and the door switch status, which provides a theoretical basis for using RFID data to monitor the door switch status.

[0045] The hardware involved in the entire hardware system includes RFID tags, RFID readers, antennas, host processors, and corresponding connecting wires between devices. The present invention deploys RFID tags and antennas in the electrical cabinet, obtains the RSSI and phase of the tag reflection signal through the RFID reader, and processes it in the host computer.

[0046] Among them, the RFID tags in the electrical cabinet are arranged in groups of three to form an equilateral triangle. This is because the metal material of the electrical cabinet has a strong reflection of the signal, and the RFID tag will have multiple paths of reflected signals superimposed, causing the signals received by the RFID reader to cancel each other out, making it impossible to obtain the RFID tag information. However, through the triangular multi-tag deployment, the RFID tags are spaced about a quarter of the wavelength apart from each other, and the reflected signals of the three RFID tags cannot be in the trough at the same time, thus ensuring that the reflected signal of at least one RFID tag can be read.

[0047] In a preferred embodiment, the side length of the equilateral triangle is about 10 cm.

[0048] In a preferred embodiment, the hardware system is deployed as follows Figure 3 shown.

[0049] 2. Software algorithm processing:

[0050] This part of the invention processes the RSSI and phase of the RFID tag reflected signal received by the RFID reader, so as to estimate the switch state of the electrical cabinet door. It mainly includes two parts: 1) anti-interference equipment state characteristics; 2) stable operation of long-term continuous perception algorithm.

[0051] (1) Anti-interference equipment status characteristics:

[0052] RSSI is weakly correlated with the state of the cabinet door and is easily affected by RFID hardware noise. In a static, closed environment, the RSSI and Phase of the RFID tag's reflected signal also change over time (this problem occurs in tags from many manufacturers). The reason for this is that the capacitors in the RFID tag's internal circuit are not strictly controlled, resulting in changes in capacitance under long-term high-frequency reading, which ultimately causes changes in RSSI and phase.

[0053] The observation value received at each moment is defined as

[0054]

[0055] in is the cumulative deviation. The present invention extracts the anti-interference feature from it:

[0056]

[0057] in It is the original feature of the reference state.

[0058] (2) Stable long-term continuous perception algorithm:

[0059] Then, based on the threshold method and state transition algorithm, the present invention constructs a low-complexity door opening and closing monitoring algorithm. The door state is divided into 0: close; 1: open. The movement of the door (tag signal fluctuation) indicates that the state has changed to 2: move. The algorithm framework is as follows Figure 2 shown.

[0060] The algorithm is specifically described in words as follows:

[0061] The open state of the cabinet door is defined as state "1", the closed state of the cabinet door is defined as state "0", the movement of the cabinet door is defined as state "2", and the abnormal data collected during monitoring is defined as state "3".

[0062] The exception handling process includes:

[0063] Judgment |y t+1 -y t |> Is δ true? If so, set S(t+1)=3; yt+1 and t represents the anti-interference feature at time t and time t+1, S(t+1)=3 means that the state at the current time, i.e., time t+1, is defined as state "3"; δ represents the anti-interference feature threshold of the exception handling process;

[0064] When S(t)=3, search forward according to the historical state until a state S(i) other than state "3" and state "2" is found, and define the state at time t+1 as state S(i): S(t+1)=S(i).

[0065] State transfer process:

[0066] Judgement t >ε is true, if so, set S(t+1)=2, and set the state at time t+1 to state "2", indicating that the cabinet door is moving at this time; ε is the anti-interference threshold during the state transfer process;

[0067] When S(t) = 2, judge |y t+1 |>γ is true, if so, set S(t+1)=1, and set the state at time t+1 to state "1"; if not, set S(t+1)=0, and set the state at time t+1 to state "0".

[0068] Keep state process:

[0069] Determine whether S(t)=0 is true:

[0070] If yes, update And let S(t+1)=0;

[0071] If not, determine whether S(t)=1 holds; if so, determine S(t+1)=1.

[0072] The state is estimated based on the currently collected RSSI and historical information (previous state, historical data), and abnormal data (interference caused by hardware thermal noise) is processed to prevent state estimation errors.

[0073] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0074] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A cabinet door switch status detection system based on RFID, characterized in that: The reflected signal of the RFID tag obtained by the RFID reader is analyzed to obtain the switch status of the door of the electrical cabinet; The detection system includes: RFID tags, RFID readers and antennas; the RFID tags and antennas are respectively deployed on the cabinet door and cabinet body in the electrical cabinet, and the RFID reader obtains the received signal strength indication and phase of the reflected signal emitted by the RFID tag via the antenna, and then analyzes the switch status of the cabinet door of the electrical cabinet; wherein, every three RFID tags form a group to form an equilateral triangle, and the interval between any two RFID tags is set to one quarter of the wavelength of the reflected signal.

2. The RFID-based cabinet door switch status detection system according to claim 1, characterized in that: It also includes the abnormal data processing process: abnormal data is processed by extracting the anti-interference characteristics of the equipment to prevent state estimation errors.

3. The RFID-based cabinet door switch status detection system according to claim 2, characterized in that: The processing of abnormal data by extracting the anti-interference characteristics of the device to prevent state estimation errors specifically includes: The received signal strength indication and phase received at the tth time are collectively referred to as the observation value x t It represents the ideal value obtained without external interference at the tth moment; in, is the cumulative deviation, This patent extracts the anti-interference feature y from the accumulated deviation t and z t : in, is the historical observation value in the closed state; y t Represents the difference between the observed value at the tth moment and the historical observed value of the door closing state, to measure the distance between states; z t It represents the variance of the observed value from the lth moment to the tth moment, so as to determine whether there is fluctuation during this period; l represents the index of the lth moment.

4. The RFID-based cabinet door switch status detection system according to claim 3, characterized in that: The method of obtaining the received signal strength indication and phase of the reflected signal sent by the RFID tag via the antenna through the RFID reader / writer, and then analyzing the switch state of the door of the electrical cabinet, specifically includes: The current switch state of the cabinet door is estimated based on the historical switch state of the cabinet door and the received signal strength indication and phase of the current and historical reflected signals.

5. The RFID-based cabinet door switch status detection system according to claim 4, characterized in that: The estimating the current switch state of the cabinet door according to the historical switch state of the cabinet door and the received signal strength indication and phase of the current and historical reflected signals specifically includes: The open state of the cabinet door is defined as state "1", the closed state of the cabinet door is defined as state "0", the movement of the cabinet door is defined as state "2", and the abnormal data collected during monitoring is defined as state "3"; The exception handling process includes: Judgment |y t+1 -y t |> Is δ true? If so, set S(t+1)=3; y t+1 and t represents the anti-interference feature at time t and time t+1, S(t+1)=3 means that the state at the current time, i.e., time t+1, is defined as state "3"; δ represents the anti-interference feature threshold of the exception handling process; When S(t) = 3, search forward according to the historical state until a state S(i) other than state "3" and state "2" is found, and the state at time t+1 is defined as state S(i): S(t+1) = S(i); State transfer process: Judgement t >ε is true, if so, set S(t+1)=2, and set the state at time t+1 to state "2", indicating that the cabinet door is moving at this time; ε is the anti-interference threshold during the state transfer process; When S(t) = 2, judge |y t+1 |> Is γ established? If so, set S(t+1)=1 and set the state at time t+1 to state "1"; if not, set S(t+1)=0 and set the state at time t+1 to state "0"; Keep state process: Determine whether S(t)=0 is true: If yes, update And let S(t+1)=0; If not, determine whether S(t)=1 holds; if so, determine S(t+1)=1.

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