A multi-frequency wireless metal anchor rod length remote measurement system
Patent Information
- Application Number
- CN202410137454.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-31
- Publication Date
- 2026-10-30
- Estimated Expiration
- 2044-01-31
AI Technical Summary
传统的驻波法通常由高精度的频率产生模块以及可控压控增益电路模块组成，因为随着扫描频率的提高激励源信号的幅值衰落地越厉害，而很难对激励源进行合适的压控增益进而影响包络电压的采集
[0012]本发明的多频率段无线通信模块拥有使用315MHz、433MHz、蓝牙2.4G三个频率段，可以进行进行半双工、全双工工作模式。从315MHz、433MHz到蓝牙2.4GHz，无线穿透能力越来越差，通信带宽越来越大，可以使用单一频率段或者多频率段通过时分复用或者频分复用满足穿透能力以及通信带宽的需求。通信对象分为多频无线金属锚杆长度远程测量系统中的多频无线通信模块和无线通信接收模块。多频无线金属锚杆长度远程测量系统中的多频无线通信模块的作用是将测量金属锚杆长度数据并将数据发送到无线通信接收模块，无线通信接收模块的作用是接收多频无线金属锚杆长度远程测量系统的数据，并将数据通过串口发送到电脑显示并存储数据。无线通信接收模块通过315MHz频段与多频无线通信模块建立连接，并要求多频无线通信模块应答，多频无线通信模块接收到应答后，将接收端关闭，避免发射端干扰，并通过3个频率段通信响应多频无线通信系统应答。无线通信接收模块接收到多频无线通信模块应答后，会根据接收频段的信号质量以及通信带宽的需求评估通信环境，选择单一或者多频段与多频无线金属锚杆长度远程测量系统中的多频无线通信系统部分建立通信连接。建立通信过程中，无线通信接收系统的接收端关闭，避免发射端干扰。多频无线通信模块统计不同频段的使用情况，使用频率不高的频率段会分配较少的运行资源。若遇到通信异常的情况，无线通信接收模块和多频无线通信模块会进行应答等待。应答等待超时后，多频无线通信模块以高主频模式运行3个频率段发射重新连接请求，并调整发射功率为最大。同时，无线通信接收模块关闭发射端打开接收端并且接收功率最大。当无线通信接收模块接收到多频无线通信模块应答后，会重新评估当前通信环境并调整发射频段以及发射功率，重新建立连接。如果无线通信接收模块在最大等待时间内未接收到多频无线通信模块的应答，则视为多频无线金属锚杆长度远程测量系统故障。本发明提供的多频无线金属锚杆长度远程测量系统可以在极为复杂的通信环境下通信，具有通信兼容性强、低功耗的优点。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of wireless remote measurement technology, specifically relating to a multi-frequency band wireless remote measurement system for metal anchor bolts. Background Technology
[0002] Measuring the length of metal anchor bolts is crucial for assessing the stability and safety of engineering structures such as tunnel supports, underground excavation support, rock anchoring, groundwater control, and earthquake protection. Accurate measurement of anchor bolt length ensures the structure can withstand anticipated loads and environmental conditions, thus guaranteeing project safety. Wireless measurement of metal anchor bolts enables real-time monitoring, improving efficiency and convenience, thereby enhancing the safety and reliability of inspections. Furthermore, wireless sensors and remote access technology allow for real-time acquisition of anchor bolt length parameters, enabling regular inspections to identify and correct problems and defects in the project, ensuring compliance with standards and design requirements.
[0003] Currently, the mainstream methods for measuring the length of metal anchor bolts include resistance measurement, ultrasonic measurement, and standing wave measurement. Due to cost and other factors, these methods, which employ direct measurement, are not convenient for long-term monitoring. The principle of resistance measurement is to wrap a uniform resistance wire around the metal anchor bolt once. The voltage drop U across the wrapped wire and the current I flowing through it are obtained by measuring the resistance wire's length, amplified by a precision operational amplifier, and processed by a digital-to-analog converter (ADC). The resistance of the wrapped wire is then calculated using Ohm's law, R = U / I. Because the resistance wire is uniform and has equal conductivity per unit meter, the length L of the metal anchor bolt is obtained using the formula L = R / Ru, where Ru is the resistance per unit meter of the resistance wire. The disadvantage of the resistance method is that the process of wrapping the resistance wire is cumbersome and easily affected by temperature, leading to significant measurement errors. The principle of ultrasonic measurement is to convert an electrical signal into an ultrasonic signal using a transducer. The ultrasonic waves propagate within the metal anchor bolt, and a portion of the ultrasonic signal is reflected back when encountering different media surfaces (i.e., the contact surface between the metal anchor bolt end and other materials). The length of the metal anchor bolt is then calculated by recording the time it takes for the ultrasonic signal to be received using a receiver. The disadvantages of ultrasonic measurement methods include the need for expensive transducers to generate ultrasonic signals and high-sensitivity receivers, resulting in poor economic viability. Furthermore, the multipath effect during ultrasonic signal propagation needs to be addressed. The standing wave method, on the other hand, works by generating a signal at a specific frequency from an excitation source. When the wavelength of this signal frequency is one-quarter of the length of the metal anchor, a standing wave signal with the same frequency but opposite direction of propagation is generated. This standing wave signal cancels out the excitation signal in the metal anchor, reducing its envelope voltage. The frequency point corresponding to the minimum envelope voltage, found through frequency scanning, represents the parameter related to the length of the metal anchor. Traditional standing wave methods typically consist of a high-precision frequency generation module and a controllable voltage-controlled gain circuit module. However, as the scanning frequency increases, the amplitude attenuation of the excitation source signal becomes more severe, making it difficult to apply appropriate voltage control to the excitation source, thus affecting the acquisition of the envelope voltage.
[0004] To address the above problems, a solution that is remotely measured, cost-effective, and highly compatible with communication is needed. This invention proposes a new solution for measuring the length of metal anchor bolts based on the standing wave method. Summary of the Invention
[0005] The purpose of this invention is to provide a multi-frequency wireless remote measurement system for the length of metal anchor bolts that is economical, adaptable to various communication environments, and has low power consumption, overcoming the inherent limitations of existing metal anchor bolt measurement systems based on the standing wave method.
[0006] The multi-frequency wireless remote measurement system for the length of metal anchor bolts provided by this invention has the following structural framework: Figure 1 The system includes a main control module, a multi-frequency wireless communication module, a detection module, a power supply module, and a battery; among which:
[0007] The main control module primarily performs frequency scanning, envelope voltage acquisition, and measurement data transmission functions. Specifically, it includes a PLL module, a PWM module, an ADC module, a GPIO module, and a USART module. The PLL module uses an internal HICK48MHz clock divided by 8 as its clock source, which also serves as the frequency source for the PWM module. The PWM module outputs a PWM wave of a specified frequency based on the PLL_Flexible mode. The ADC module is used to acquire the envelope voltage of the detector module. The GPIO module serves as a communication data port for 433MHz and 315MHz. The USART module is used for communication with the Bluetooth 2.4G module.
[0008] The multi-frequency wireless communication module includes a transmitting antenna, a receiving antenna, a 433MHz module, a 315MHz module, and a Bluetooth 2.4G module. These three modules are used to implement communication functions.
[0009] The detection module consists of a low-pass filter and a Zener diode, used to extract the envelope voltage of the swept frequency signal; the power supply module mainly consists of a linear voltage regulator module and a filter circuit, used to supply power to the main control unit and the multi-frequency wireless communication system.
[0010] The multi-frequency wireless remote measurement system for the length of metal anchor bolts provided by this invention is based on the standing wave method. First, the PLL clock source is set to HICK48MHz. Then, based on the PLL_Flexible mode, a high-precision scanning frequency signal is output and coupled with the metal anchor bolt, and the envelope voltage is extracted to obtain the frequency point corresponding to the minimum envelope voltage. The length of the metal anchor bolt is then calculated using this frequency point, and the data is transmitted through the multi-frequency wireless communication module.
[0011] This invention measures the length of a metal anchor bolt based on the standing wave method. Data is transmitted from the multi-frequency wireless communication module of a multi-frequency wireless metal anchor bolt length remote measurement system to a wireless communication receiving module. The wireless communication receiving module is also a multi-frequency wireless communication module, which transmits data to a computer via a serial port for display and storage. First, a nut with the multi-frequency wireless metal anchor bolt length remote measurement system attached is fastened to the metal anchor bolt to be measured. The length of the metal anchor bolt is measured based on the standing wave method, with the scanning frequency range set to 6-65MHz and the frequency step to 0.25MHz. The system controls the PWM module to output the scanning frequency signal by changing the output frequency of the PLL module. After a delay of 1500ms, the envelope voltage of the detector module is acquired and saved by the ADC module of the main control unit. Then, the scanning frequency is increased by 0.25MHz based on the PLL_Flexible mode. When the scanning frequency reaches 65MHz, the frequency scan ends. Using the previously acquired envelope voltage, the frequency point f1 corresponding to the minimum envelope voltage is found. The length L1 of the metal anchor bolt to be measured can be calculated using the formula L1=(L0*f0) / f1. Where L0 is the known length of a metal anchor rod of the same material, and f0 is the frequency point corresponding to the minimum envelope voltage of the metal anchor rod of the same material. After obtaining the length L1 of the metal anchor rod, the metal anchor rod length data L1 is sent to the wireless communication receiving module through the multi-frequency wireless communication module of the multi-frequency wireless metal anchor rod length remote measurement system. The wireless communication receiving module sends the metal anchor rod length data L1 to the computer for display and storage via serial port.
[0012] This invention's multi-band wireless communication module utilizes three frequency bands: 315MHz, 433MHz, and Bluetooth 2.4GHz, enabling half-duplex and full-duplex operation. From 315MHz and 433MHz to Bluetooth 2.4GHz, wireless penetration decreases while communication bandwidth increases. Single or multiple frequency bands can be used through time-division multiplexing or frequency-division multiplexing to meet the requirements for penetration and bandwidth. The communication objects are divided into a multi-band wireless communication module and a wireless communication receiving module in the multi-band wireless metal anchor length remote measurement system. The multi-band wireless communication module measures the length of the metal anchor and transmits it to the wireless communication receiving module. The receiving module receives the data from the multi-band wireless metal anchor length remote measurement system and transmits it to a computer for display and storage via a serial port. The receiving module establishes a connection with the multi-band wireless communication module via the 315MHz band and requests a response. Upon receiving the response, the multi-band wireless communication module shuts down its receiver to avoid interference from the transmitter and responds to the multi-band wireless communication system's response via communication across the three frequency bands. After receiving a response from the multi-frequency wireless communication module, the wireless communication receiving module assesses the communication environment based on the signal quality and bandwidth requirements of the receiving frequency band. It then selects one or more frequency bands to establish a communication connection with the multi-frequency wireless communication system portion of the multi-frequency wireless metal anchor length remote measurement system. During communication establishment, the receiving end of the wireless communication receiving system is turned off to avoid interference from the transmitting end. The multi-frequency wireless communication module analyzes the usage of different frequency bands, allocating fewer operating resources to frequency bands with lower usage. If a communication anomaly is encountered, both the wireless communication receiving module and the multi-frequency wireless communication module will wait for a response. After the response wait times out, the multi-frequency wireless communication module operates in high-frequency mode, transmitting reconnection requests across three frequency bands and adjusting the transmission power to maximum. Simultaneously, the wireless communication receiving module turns off the transmitting end and turns on the receiving end with maximum receiving power. When the wireless communication receiving module receives a response from the multi-frequency wireless communication module, it reassesses the current communication environment, adjusts the transmitting frequency band and transmission power, and re-establishes the connection. If the wireless communication receiving module does not receive a response from the multi-frequency wireless communication module within the maximum waiting time, it is considered a fault in the multi-frequency wireless metal anchor length remote measurement system. The multi-frequency wireless remote measurement system for metal anchor bolt length provided by this invention can communicate in extremely complex communication environments and has the advantages of strong communication compatibility and low power consumption. Attached Figure Description
[0013] Figure 1 This is a framework diagram of a multi-frequency wireless remote measurement system for the length of metal anchor bolts.
[0014] Figure 2 This is a schematic diagram of a multi-frequency wireless remote measurement system for the length of metal anchor bolts, and a schematic diagram of the system attached to a nut.
[0015] Figure 3 A diagram showing a nut attached to an anchor bolt for a multi-frequency wireless metal anchor bolt length remote measurement system, which measures the anchor bolt length and then sends the data to a multi-frequency wireless communication system.
[0016] Figure 4 This is a flowchart illustrating the measurement of anchor bolt length based on the standing wave method of this invention.
[0017] Figure 5 This invention uses the PLL_Flexible mode to change the main frequency of the main control module and overclock the output scanning frequency signal of the PWM module.
[0018] Figure 6 The communication process of the multi-frequency band communication module of the present invention is as follows.
[0019] Figure 7 This is the communication anomaly resolution process for the multi-frequency band communication module of the present invention. Detailed Implementation
[0020] This invention utilizes electronic encapsulation for potting, improving system stability and impact resistance. When potting the multi-frequency wireless metal anchor length remote measurement system, the transmitting and receiving antennas of the system must be exposed. Figure 2 Left. After applying adhesive to the system, it needs to be attached to the nut for direct coupling to the metal anchor. This can be achieved by applying adhesive to both the system and the side of the nut with the system attached during the adhesive application process, resulting in a stable hold. Figure 2 right.
[0021] Use the demonstration diagram as shown below Figure 3 The nut for the multi-frequency wireless remote measurement system of metal anchor bolt length can be fastened to the metal anchor bolt, ensuring good contact between the system and the anchor bolt. After coupling with the metal anchor bolt, the multi-frequency wireless remote measurement system will activate the standing wave scanning frequency function to measure the length of the metal anchor bolt. After measuring the length, the multi-frequency wireless remote measurement system will save the data and passively send data to the multi-frequency wireless communication module, awaiting a query from the multi-frequency wireless communication system. Upon receiving the data, the multi-frequency wireless communication system will send it to the computer via serial port for display.
[0022] The procedure for measuring the length of metal anchor bolts based on the standing wave method is as follows: Figure 4First, the standing wave (SWR) frequency scanning function is activated, setting the scanning frequency range to 6MHz-65MHz with a frequency step of 0.25MHz. Then, based on the PLL_Flexible mode, appropriate parameters are set to generate a PWM wave at the specified frequency, where the PWM wave is set as a square wave with a 50% duty cycle. After setting the output PWM wave frequency, a 1500ms delay is applied to stabilize the SWR signal. Next, the ADC module inside the main control unit is activated to acquire the envelope voltage through the detection module, acquiring and saving the envelope voltage at each frequency point. The scanning frequency signal is increased by 0.25MHz until the scanning frequency reaches 65MHz, at which point the SWR frequency scanning function is stopped. After the frequency sweep is complete, the main control unit finds the frequency point f1 corresponding to the minimum envelope voltage. The length L1 of the metal anchor rod to be measured is calculated using the formula L1 = (L0*f0) / f1. After obtaining the metal anchor rod length data, the multi-frequency wireless metal anchor rod length remote measurement system stores the metal anchor rod length data L1, waiting for the multi-frequency wireless communication system to query and passively transmit data to the multi-frequency wireless communication module. After receiving data, the multi-frequency wireless communication module sends the data to the computer via serial port. The computer then displays and saves the measured length L1 of the metal anchor bolt by the multi-frequency wireless metal anchor bolt length remote measurement system. At a room temperature of 25 degrees Celsius, the measurement error for 3 meters of 20MnSi steel reinforcement in a reinforced concrete structure is within 3%. In environments ranging from 25 degrees Celsius to -15 degrees Celsius, the measurement error deviation is less than 0.5%, demonstrating high measurement accuracy and good performance in varying temperature conditions.
[0023] like Figure 5 Based on the AT32F421C8T7 main control chip, a high-speed internal 48MHz clock (HICK) is selected, divided by 6 (8MHz) and then by 2 (4MHz) to become the PLL clock source. The PLL Mode is then set to PLL_Flexible mode. At this point, the output system clock frequency (SCLK) can be set by configuring the three parameters pll_ms, pll_ns, and pll_fr. The system clock frequency (SCLK) and the three PLL module parameters have the following relationship: SCLK = (4 * pll_ns) / (pll_ms * pll_fr). Afterwards, by changing the system clock frequency (SCLK), the PWM module is set to use a 1:1 ratio of positive to negative pulse duration (50%) as the output scanning signal. When generating a high-frequency scanning signal, it needs to be higher than the upper limit of the IO port output frequency. This can be achieved by overclocking the main control chip, i.e., making the system clock frequency (SCLK) greater than the chip manufacturer's maximum operating frequency. During overclocking, it is crucial to ensure stable voltage and power supply to the power module. Based on the PLL_Flexible mode, a high-precision scanning frequency signal can be output through the PWM module, which can replace the expensive scanning frequency module and controllable voltage-controlled gain module in traditional standing wave measurement, thus having good economic applicability.
[0024] The multi-frequency band communication system includes three frequency bands: 315MHz, 433MHz, and Bluetooth 2.4G. The communication process is as follows: Figure 6 The multi-frequency wireless communication system requests a response from the multi-frequency wireless metal anchor length remote measurement system via the 315MHz band (which has the best penetration capability). The passive response frequency division multiplexing (FDM) of the multi-frequency wireless metal anchor length remote measurement system transmits the response to the multi-frequency wireless communication system via three frequency bands. During response transmission, the multi-frequency wireless communication system portion of the system shuts down its receiver to avoid interference. After transmission, it waits for a period before resuming receiving the multi-frequency wireless communication system's frequency bands. The multi-frequency wireless communication system selects the appropriate frequency band for communication based on the reception of the three frequency bands and the required communication bandwidth. The system allocates resources based on the usage frequency of a particular frequency band; modules operating on less frequently used frequency bands receive less operating resources, either by switching to a lower main frequency mode or even shutting down to reduce power consumption.
[0025] In some special circumstances, a communication may fail, such as Figure 7 The multi-frequency wireless metal anchor length remote measurement system, after a response timeout, did not receive a response from the multi-frequency wireless communication system. The multi-frequency wireless metal anchor length remote measurement system then requested a reconnection by operating at a high master frequency across three frequency bands and adjusting its transmit power to maximum. Simultaneously, the multi-frequency wireless communication system, after also not receiving a response after the response timeout, shut down its transmitter and set its receiver sensitivity and power to maximum. After re-establishing a connection between the multi-frequency wireless communication system and the multi-frequency wireless metal anchor length remote measurement system, it assessed the current communication environment and selected a suitable communication frequency band. If the multi-frequency wireless communication system still does not receive a response from the multi-frequency wireless metal anchor length remote measurement system after waiting for the maximum timeout period, it is considered a malfunction of the multi-frequency wireless metal anchor length remote measurement system.
Claims
1. A multi-frequency wireless remote measurement system for the length of metal anchor bolts, characterized in that, It includes a main control module, a multi-frequency wireless communication module, a detection module, and a power supply module; among which: The main control module performs frequency scanning, envelope voltage acquisition, and measurement data transmission functions. Specifically, it includes a PLL module, a PWM module, an ADC module, a GPIO module, and a USART module. The PLL module uses an internal HICK48MHz clock divided by 8 as its clock source, which also serves as the frequency source for the PWM module. The PWM module outputs a PWM wave of a specified frequency based on the PLL_Flexible mode. The ADC module is used to acquire the envelope voltage of the detector module. The GPIO module serves as a communication data port for 433MHz and 315MHz. The USART module is used to communicate with the Bluetooth 2.4G module. The multi-frequency wireless communication module includes a transmitting antenna, a receiving antenna, a 433MHz module, a 315MHz module, and a Bluetooth 2.4G module, which are used to realize communication functions. The detection module consists of a low-pass filter and a Zener diode, and is used to extract the envelope voltage of the swept frequency signal; The power supply module consists of a linear voltage regulator module and a filter circuit, and is used to supply power to the main control unit and the multi-frequency wireless communication system.
2. The multi-frequency wireless remote measurement system for the length of metal anchor bolts according to claim 1, characterized in that, The length of the metal anchor rod is remotely measured using the standing wave method. First, the PLL clock source is set to HICK48MHz. Then, a high-precision scanning frequency signal is output based on the PLL_Flexible mode and coupled with the metal anchor rod. The envelope voltage is extracted to obtain the frequency point corresponding to the minimum envelope voltage. The length of the metal anchor rod is then calculated using this frequency point, and the data is transmitted through a multi-frequency wireless communication module.
3. The multi-frequency wireless remote measurement system for the length of metal anchor bolts according to claim 2, characterized in that, The procedure for remotely measuring the length of a metal anchor bolt using the standing wave method is as follows: First, the nut of the multi-frequency wireless metal anchor length remote measurement system is fastened to the metal anchor to be measured. The scanning frequency range is set to 6-65MHz with a frequency step of 0.25MHz. The scanning frequency signal is controlled by the output frequency of the PLL module to control the output frequency of the PWM module. After a delay of 1500ms, the envelope voltage of the detector module is acquired and saved by the ADC module of the main control module. Then, the scanning frequency is increased by 0.25MHz based on the PLL_Flexible mode. When the scanning frequency is increased to 65MHz, the frequency scan ends. The frequency point f1 corresponding to the minimum envelope voltage is found by the previously acquired envelope voltage. The length L1 of the metal anchor to be measured is calculated by the formula L1 = (L0* f0) / f1. Where L0 is the known length of a metal anchor rod of the same material, and f0 is the frequency point corresponding to the minimum envelope voltage of the metal anchor rod of the same material; after obtaining the length L1 of the metal anchor rod, the metal anchor rod length data L1 is sent to the wireless communication receiving module through the multi-frequency wireless communication module, and the wireless communication receiving module sends the data to the computer for display and storage through the serial port.
4. The multi-frequency wireless remote measurement system for the length of metal anchor bolts according to claim 3, characterized in that, Multi-band wireless communication modules use three frequency bands: 315MHz, 433MHz, and Bluetooth 2.4G, and operate in both half-duplex and full-duplex modes. From 315MHz and 433MHz to Bluetooth 2.4GHz, wireless penetration capability decreases while communication bandwidth increases. Using a single frequency band or multiple frequency bands through time division multiplexing or frequency division multiplexing can meet the requirements for penetration capability and communication bandwidth. The communication system consists of a multi-frequency wireless communication module and a wireless communication receiving module. The multi-frequency wireless communication module transmits the measured length data of the metal anchor bolt to the wireless communication receiving module. The wireless communication receiving module receives data from the multi-frequency wireless metal anchor bolt length remote measurement system and transmits it to a computer for display and storage via a serial port. The wireless communication receiving module establishes a connection with the multi-frequency wireless communication module via the 315MHz frequency band and requests a response from the multi-frequency wireless communication module. Upon receiving the response, the multi-frequency wireless communication module shuts down its receiver to avoid interference from the transmitter and responds to the multi-frequency wireless communication module's response via three frequency bands. After receiving the response from the multi-frequency wireless communication module, the wireless communication receiving module selects one or more frequency bands to establish a communication connection with the multi-frequency wireless communication module. During the communication establishment process, the wireless communication receiving module... The receiving end is turned off to avoid interference from the transmitting end; the multi-frequency wireless communication module counts the usage of different frequency bands, allocating less operating resources to frequency bands with low usage; if a communication anomaly is encountered, the wireless communication receiving module and the multi-frequency wireless communication module respond and wait; after the response waiting timeout, the multi-frequency wireless communication module operates in high master frequency mode, transmitting reconnection requests on three frequency bands and adjusting the transmission power to maximum; simultaneously, the wireless communication receiving module turns off the transmitting end and turns on the receiving end with maximum receiving power; when the wireless communication receiving module receives the response from the multi-frequency wireless communication module, it will reassess the current communication environment and adjust the transmitting frequency band and transmission power to re-establish the connection; if the wireless communication receiving module does not receive the response from the multi-frequency wireless communication module within the maximum waiting time, it is considered a fault in the multi-frequency wireless metal anchor length remote measurement system.