A passive tag based touch input method and apparatus

Abstract

The application discloses a touch input method and system based on passive tags, which continuously reads the electronic code and the reflection signal strength of each RFID tag in an RFID tag array through an RFID reader, carries out smoothing processing on the read reflection signal strength, obtains smooth data, then uses a variance method to obtain smooth variance data, and judges the smooth data and the smooth variance data of each RFID tag obtained continuously to identify whether a touch event occurs to each RFID tag. The touch input realized by the application through radio frequency passive tag technology, compared with a traditional interaction mode, saves expensive sensing hardware, removes a high-power consumption wireless sensor node and a complex wireless communication module, realizes battery-free application, and has the advantages of passivity, low cost and expansibility.

Description

Technical Field

[0001] This application belongs to the field of wireless communication technology, specifically relating to a touch input method and device based on passive tags. Background Technology

[0002] With the rapid development of the Internet of Things (IoT), the total number of IoT connections worldwide is increasing rapidly. The future of IoT requires seamless and convenient interaction between devices and users, which necessitates the use of various human-computer interaction methods. Traditional touch interaction requires additional dedicated hardware costs and power supplies, limiting the flexibility and applicability of ubiquitous computing applications. Vision-based solutions for touch input can reduce the additional hardware costs associated with the touch object. However, vision-based methods are limited by the gaze limitation.

[0003] UHF RFID technology is a non-contact automatic identification technology. It consists of a reader and tags. The reader reads and writes tag information, while the tag comprises an antenna and a chip, each with a globally unique EPC (Electronic Packet Code). The UHF RFID system works by broadcasting a carrier signal carrying energy and information to its surroundings. The tag captures the carrier signal energy to power its chip and then transmits its data back to the reader via backscattering. A key feature of UHF RFID systems is that the tag does not require an external power supply; its operation is powered by the radio frequency signal transmitted by the reader. Its primary functions are identification and location, and it is widely used for tracking, locating, and inventory management, such as in logistics management, supermarket management, and warehouse management. UHF RFID technology offers advantages such as low power consumption, low cost, and a simple communication protocol.

[0004] However, RFID tags can only send the data inherent in the tag, not variable data; that is, they do not have the ability to send sensor data. Summary of the Invention

[0005] The purpose of this application is to provide a touch input method and device based on passive tags to solve the problems of high hardware cost, high power consumption of wireless communication modules, limited line of sight, and inability of UHF RFID technology to transmit sensor data in traditional interaction modes.

[0006] To achieve the above objectives, the technical solution of this application is as follows:

[0007] A passive tag-based touch input device includes:

[0008] An RFID reader is used to continuously read the electronic code and reflected signal strength of each RFID tag in an RFID tag array;

[0009] The reflection signal processing module is used to smooth the intensity of the read reflection signal to obtain smoothed data, and then the variance method is used to obtain smoothed variance data.

[0010] The touch event recognition module is used to judge the smoothed data and smoothed variance data of each RFID tag that are continuously acquired, and to identify whether a touch event has occurred on each RFID tag.

[0011] Furthermore, the reflection signal processing module smooths the read reflection signal intensity to obtain smoothed data, and then uses the variance method to obtain smoothed variance data, performing the following operations:

[0012] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0013] The variance of the smoothed data is calculated using the first sliding window to obtain the smoothed variance data.

[0014] Furthermore, the reflection signal processing module smooths the read reflection signal intensity to obtain smoothed data, and then uses the variance method to obtain smoothed variance data, performing the following operations:

[0015] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0016] The variance of the smoothed data is calculated using the first sliding window;

[0017] The variance of the smoothed data is calculated again using a second sliding window to obtain the smoothed variance data.

[0018] Furthermore, the touch event recognition module judges the smoothed data and smoothed variance data of each continuously acquired RFID tag to identify whether a touch event has occurred for each RFID tag, and performs the following operations:

[0019] For each RFID tag, continuously observe its corresponding smoothed variance data. If the smoothed variance data experiences two typical waves starting from zero, and the smoothed variance data is higher than the set threshold when it is at the trough, then a touch event is determined to have occurred.

[0020] Furthermore, adjacent RFID tags in the RFID tag array are arranged orthogonally in pairs.

[0021] This application also proposes a touch input method based on passive tags, including:

[0022] The electronic code and reflected signal strength of each RFID tag in the RFID tag array are continuously read by an RFID reader;

[0023] The intensity of the read reflected signal is smoothed to obtain smoothed data, and then the variance method is used to obtain smoothed variance data.

[0024] The smoothed data and smoothed variance data of each RFID tag are continuously acquired to determine whether a touch event has occurred on each RFID tag.

[0025] Furthermore, the process of smoothing the read reflected signal intensity to obtain smoothed data, and then using the variance method to obtain smoothed variance data, includes:

[0026] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0027] The variance of the smoothed data is calculated using the first sliding window to obtain the smoothed variance data.

[0028] Furthermore, the process of smoothing the read reflected signal intensity to obtain smoothed data, and then using the variance method to obtain smoothed variance data, includes:

[0029] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0030] The variance of the smoothed data is calculated using the first sliding window;

[0031] The variance of the smoothed data is calculated again using a second sliding window to obtain the smoothed variance data.

[0032] Furthermore, the step of judging the smoothed data and smoothed variance data of each continuously acquired RFID tag to identify whether a touch event has occurred on each RFID tag includes:

[0033] For each RFID tag, continuously observe its corresponding smoothed variance data. If the smoothed variance data experiences two typical waves starting from zero, and the smoothed variance data is higher than the set threshold when it is at the trough, then a touch event is determined to have occurred.

[0034] Furthermore, adjacent RFID tags in the RFID tag array are arranged orthogonally in pairs.

[0035] This application proposes a passive tag-based touch input method and system. Utilizing existing mature commercial RFID technology, it expands the functionality of traditional RFID systems, enabling touch interaction. Compared to traditional interaction modes, it eliminates expensive sensing hardware, removes the high power consumption of wireless sensor nodes and complex wireless communication modules, achieving battery-free applications. This application leverages the passive, low-cost, and scalable advantages of UHF RFID technology, employing radio frequency passive tag technology for touch input. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the passive tag-based touch input device of this application.

[0037] Figure 2 This is a schematic diagram of the label matrix arrangement in an embodiment of this application.

[0038] Figure 3 This is a waveform diagram of the reflected signal intensity in an embodiment of this application.

[0039] Figure 4 This is a waveform diagram of smoothed variance data in an embodiment of this application.

[0040] Figure 5 This is a flowchart illustrating the touch event recognition module's process for recognizing touch events in an embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0042] The general idea of ​​this application is to read the EPC (Electronic Code) and RSS value of an RFID tag using an RFID reader, and then process the RSS value to identify whether a touch event has occurred on the RFID tag. By forming a tag array with multiple RFID tags, the touch event of each tag is identified, thereby obtaining the specific tag EPC number corresponding to the touch, realizing touch input based on passive tags.

[0043] In one embodiment, such as Figure 1 As shown, a touch input device based on a passive tag is proposed, comprising:

[0044] An RFID reader is used to continuously read the electronic code and reflected signal strength of each RFID tag in an RFID tag array;

[0045] The reflection signal processing module is used to smooth the intensity of the read reflection signal to obtain smoothed data, and then the variance method is used to obtain smoothed variance data.

[0046] The touch event recognition module is used to judge the smoothed data and smoothed variance data of each RFID tag that are continuously acquired, and to identify whether a touch event has occurred on each RFID tag.

[0047] Specifically, such as Figure 1 As shown, this embodiment of the passive tag-based touch input device includes an RFID reader, a reflective signal processing module, and a touch event recognition module, corresponding to... Figure 1The left side of the middle section. An RFID tag array is a touch keyboard composed of multiple RFID tags; in this embodiment, it is referred to as an RFID tag array.

[0048] It's easy to understand that when an RFID reader reads an RFID tag, the RFID reader sends a radio frequency signal to the RFID tag. After receiving the radio frequency signal, the RFID tag reflects its EPC number (i.e., electronic code) along with the radio frequency signal back to the RFID reader. Thus, the RFID reader can interpret the EPC number and RSS value (reflected signal strength) based on the received reflected signal.

[0049] In this embodiment, the RFID reader periodically and continuously reads the RFID tag array to obtain the reflected signal of each RFID tag, thereby obtaining the EPC number and RSS value of each RFID tag.

[0050] In one specific embodiment, the reflection signal processing module smooths the intensity of the read reflection signal to obtain smoothed data, and then uses the variance method to obtain smoothed variance data, performing the following operations:

[0051] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0052] The variance of the smoothed data is calculated using the first sliding window to obtain the smoothed variance data.

[0053] Specifically, the reflected signal involves noise and multipath interference, requiring preprocessing. In this embodiment, a moving average filter is used to smooth the reflected signal intensity RSS stream data. The smoothed data S(i) is calculated by equation (1):

[0054]

[0055] Where N is the sliding window size of the moving average filter, R(x) represents the reflected signal intensity data stream, and [] denotes rounding. S(i) represents the i-th data point in the smoothed data.

[0056] To improve touch reliability, the variance method is used to process the smoothed data. The variance of the smoothed data is calculated using the first sliding window to obtain the smoothed variance data V(i), which is then calculated using equation (2):

[0057]

[0058] Where A(i) is the average value of the smoothed data when the first sliding window size is M, M is the size of the first sliding window, and [] indicates rounding.

[0059] To overcome calibration issues during deployment and reduce deployment errors, this application again employs the variance method to smooth the variance data during non-touch periods and amplify the variance data during touch periods. Specifically, in another specific embodiment, the reflection signal processing module smooths the read reflection signal intensity to obtain smoothed data, and then uses the variance method to obtain smoothed variance data, performing the following operations:

[0060] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0061] The variance of the smoothed data is calculated using the first sliding window;

[0062] The variance of the smoothed data is calculated again using a second sliding window to obtain the smoothed variance data.

[0063] In this embodiment, the smoothed variance data VoV(i) is calculated using the second sliding window, which is calculated by equation (3):

[0064]

[0065] Where B(i) is the average variance of the smoothed data when the second sliding window size is K, K is the second sliding window size, and [] indicates rounding.

[0066] Since the data obtained after the first variance analysis still cannot effectively remove the minute data changes during non-touch periods, this embodiment uses the second variance analysis to obtain smoothed variance data, which can effectively remove minute data changes and make subsequent touch recognition more accurate.

[0067] This application performs touch recognition based on the fact that finger touch causes a significant increase in the RSS value of the touched tag. When a significant increase in the RSS value is detected at a certain moment, the touch tag is determined based on the EPC number corresponding to that RSS value. The RSS value represents the signal strength of the received reflected signal. Since this value is affected by factors such as the distance between the tag and the reader antenna, obstruction between the tag and the reader antenna, and coupling between tags, this application performs touch recognition by processing the RSS value.

[0068] The simplest method for a touch event recognition module is to check if the RSS value is greater than a set threshold; if it is, a touch event is determined to have occurred. Alternatively, it can directly check if the variance of the smoothed data calculated by the first sliding window is greater than a set threshold. To make touch recognition more accurate, this application processes the RSS value to calculate VoV(i) before performing touch event recognition.

[0069] In one specific embodiment, the touch event recognition module judges the smoothed data and smoothed variance data of each continuously acquired RFID tag to identify whether a touch event has occurred for each RFID tag, and performs the following operations:

[0070] For each RFID tag, continuously observe its corresponding smoothed variance data. If the smoothed variance data experiences two typical waves starting from zero, and the smoothed variance data is higher than the set threshold when it is at the trough, then a touch event is determined to have occurred.

[0071] The waveform of the reflected signal strength is continuously read over a period of time using an RFID reader, such as... Figure 3 As shown, after smoothing and variance calculation, the smoothed variance data VoV(i) waveform is as follows: Figure 4 As shown. Combining these two graphics, this embodiment determines whether a touch event has occurred, as follows: Figure 5 As shown, observe whether the smoothed variance data over a time period experiences two typical waves starting from zero. Here, the typical waves are the smoothed variance data, such as... Figure 4 If the M-wave in the data passes through two M-waves, and the smoothed data is above the set threshold when the smoothed variance data is at the trough, then a touch event is determined to have occurred; otherwise, it is determined to be no touch event.

[0072] It should be noted that the RFID reader in this application records the reading time while reading RFID tags, continuously reading to obtain the reflected signal strength at different times for subsequent processing and judgment. During reading, the EPC information of the RFID tag is also read, allowing for the differentiation of different RFID tags and thus identifying which tags in the tag array have been touched. Since each RFID tag has a unique EPC, different tags can be distinguished by their EPC. Therefore, even if there are multiple touch keys within the RFID reader's readable range, touches can be detected and differentiated, supporting event sensing for multiple touch keys.

[0073] In one specific embodiment, different commercial RFID tags can be selected according to requirements, such as the Alien 9629, because its rectangular shape makes it easy to combine into arrays for deployment. The RFID reader reads the information from the RFID tags using commercial RFID protocols. Preferably, a suitable UHF reader can be used, such as the Impinj R420, which supports the 915MHz band. This reader can support four antennas, which can extend the coverage area.

[0074] In one specific embodiment, an RFID tag array such as Figure 2As shown, adjacent RFID tags are arranged orthogonally in pairs to eliminate coupling effects. This embodiment is not limited to the number of tags contained in a tag array, which will not be elaborated here.

[0075] It should be noted that the size of each sliding window and the distance between RFID tags used in this application can be determined through experiments based on actual needs, and this application does not impose any restrictions on these parameters.

[0076] In another embodiment, this application also provides a touch input method based on passive tags, comprising:

[0077] The electronic code and reflected signal strength of each RFID tag in the RFID tag array are continuously read by an RFID reader;

[0078] The intensity of the read reflected signal is smoothed to obtain smoothed data, and then the variance method is used to obtain smoothed variance data.

[0079] The smoothed data and smoothed variance data of each RFID tag are continuously acquired to determine whether a touch event has occurred on each RFID tag.

[0080] In one specific implementation of this embodiment, the step of smoothing the read reflected signal intensity to obtain smoothed data, and then using the variance method to obtain smoothed variance data, includes:

[0081] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0082] The variance of the smoothed data is calculated using the first sliding window to obtain the smoothed variance data.

[0083] Another specific implementation of this embodiment, wherein the reading reflected signal intensity is smoothed to obtain smoothed data, and then the variance method is used to obtain smoothed variance data, includes:

[0084] The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data;

[0085] The variance of the smoothed data is calculated using the first sliding window;

[0086] The variance of the smoothed data is calculated again using a second sliding window to obtain the smoothed variance data.

[0087] In one specific implementation of this embodiment, the step of judging the smoothed data and smoothed variance data of each continuously acquired RFID tag to identify whether a touch event has occurred on each RFID tag includes:

[0088] For each RFID tag, continuously observe its corresponding smoothed variance data. If the smoothed variance data experiences two typical waves starting from zero, and the smoothed variance data is higher than the set threshold when it is at the trough, then a touch event is determined to have occurred.

[0089] The specific implementation methods described above have been elaborated in detail in the device description and will not be repeated here.

[0090] In a typical application, the passive tag-based touch input device of this application can be interconnected with an electronic door lock. Users can set access control passwords in advance. By naming different tag EPC numbers with different numerical serial numbers (1 to 9), different numerical inputs can be obtained after multiple tags are detected to have touch events. By comparing the input numbers with the access control password, a passive electronic combination lock can be realized.

[0091] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A touch input device based on a passive tag, characterized in that, The passive tag-based touch input device includes: An RFID reader is used to continuously read the electronic code and reflected signal strength of each RFID tag in an RFID tag array; The reflection signal processing module is used to smooth the intensity of the read reflection signal to obtain smoothed data, and then the variance method is used to obtain smoothed variance data. The touch event recognition module is used to judge the smoothed data and smoothed variance data of each continuously acquired RFID tag, identify whether a touch event has occurred on each RFID tag, and perform the following operations: For each RFID tag, continuously observe its corresponding smoothed variance data. If the smoothed variance data experiences two m-shaped waves starting from zero, and the smoothed variance data is higher than the set threshold when it is at the trough, then a touch event is determined to have occurred.

2. The touch input device based on a passive tag according to claim 1, characterized in that, The reflection signal processing module smooths the intensity of the read reflection signal to obtain smoothed data, and then uses the variance method to obtain smoothed variance data, performing the following operations: The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data; The variance of the smoothed data is calculated using the first sliding window to obtain the smoothed variance data.

3. The touch input device based on a passive tag according to claim 1, characterized in that, The reflection signal processing module smooths the intensity of the read reflection signal to obtain smoothed data, and then uses the variance method to obtain smoothed variance data, performing the following operations: The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data; The variance of the smoothed data is calculated using the first sliding window; The variance of the smoothed data is calculated again using a second sliding window to obtain the smoothed variance data.

4. The touch input device based on a passive tag according to claim 1, characterized in that, In the RFID tag array, adjacent RFID tags are arranged orthogonally in pairs.

5. A touch input method based on passive tags, characterized in that, The passive tag-based touch input method includes: The electronic code and reflected signal strength of each RFID tag in the RFID tag array are continuously read by an RFID reader; The intensity of the read reflected signal is smoothed to obtain smoothed data, and then the variance method is used to obtain smoothed variance data. The smoothed data and smoothed variance data of each RFID tag are continuously obtained to determine whether a touch event has occurred for each RFID tag. This includes: continuously observing the corresponding smoothed variance data of each RFID tag; if the smoothed variance data goes through two m-shaped waves from zero point, and the smoothed data is higher than the set threshold when the smoothed variance data is at the trough of the wave, then a touch event is determined to have occurred.

6. The touch input method based on passive tags according to claim 5, characterized in that, The process of smoothing the read reflected signal intensity to obtain smoothed data, and then using the variance method to obtain smoothed variance data, includes: The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data; The variance of the smoothed data is calculated using the first sliding window to obtain the smoothed variance data.

7. The touch input method based on passive tags according to claim 5, characterized in that, The process of smoothing the read reflected signal intensity to obtain smoothed data, and then using the variance method to obtain smoothed variance data, includes: The intensity of the reflected signal is smoothed using a moving average filter to obtain smoothed data; The variance of the smoothed data is calculated using the first sliding window; The variance of the smoothed data is calculated again using a second sliding window to obtain the smoothed variance data.

8. The touch input method based on passive tags according to claim 5, characterized in that, In the RFID tag array, adjacent RFID tags are arranged orthogonally in pairs.

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