Method and system for preventing signal interference among multiple ultrasonic distance measuring sensors

Abstract

The invention relates to the technical field of signal anti-interference of multiple ultrasonic distance measuring sensors, in particular to a method and system for signal anti-interference among multiple ultrasonic distance measuring sensors, and the method comprises the steps: setting the total number of sensors and unique ID identifiers through an upper computer, and connecting the sensors in parallel through an RS485 interface; and the signal interference is reduced by independently working in different time periods according to an ID sequence. The method supports multiple installation modes (same-direction side-by-side installation, opposite-direction installation and vertical installation), can compensate a detection blind area and realize corner position detection, and meanwhile, ensures that the position change of the workpiece is in a controllable state. The time interval T is greater than or equal to 2TOFmax, and the signals are ensured to be free from conflicts. The system is composed of a setting module, a communication module, a control module, an execution module and an output module, and multi-mode data interaction and distance measurement value output are achieved. The technical effects of effectively preventing signal interference among the multiple ultrasonic distance measuring sensors and improving the detection precision and the system stability are achieved.

Description

Technical Field

[0001] This application relates to the technical field of signal anti-interference for multi-ultrasonic ranging sensors, and particularly to a method and system for signal anti-interference between multi-ultrasonic ranging sensors. Background Art

[0002] Ultrasonic ranging technology is widely used in fields such as industrial automation, logistics warehousing, and intelligent manufacturing. Its core principle is to calculate the distance to the target object through the time difference between transmitting and receiving ultrasonic signals. In modern industrial production, ultrasonic sensors are widely used for detecting workpiece positions, monitoring material flow, and realizing automatic control due to their non-contact measurement, high precision, and low cost. However, with the complexity of application scenarios, the collaborative work of multiple sensors has become an inevitable trend, which poses higher requirements for signal anti-interference between sensors.

[0003] In the prior art, to solve the signal interference problem when multiple ultrasonic sensors work simultaneously, the following methods are usually adopted: one is to increase the installation distance between sensors to ensure that ultrasonic signals do not overlap with each other; the second is to connect the external input synchronization signal lines of multiple sensors together and reduce interference by synchronously transmitting ultrasonic signals; the third is to limit the installation method of sensors to side-by-side arrangement in the same direction to reduce signal cross-interference. Although these methods can alleviate the interference problem to a certain extent, they have obvious limitations.

[0004] The main defects of the above methods are that, on the one hand, it is required that the installation distance between two adjacent sensors must be greater than the minimum distance that will cause interference, otherwise it will lead to confusion in the sensor detection values or misjudgment; on the other hand, the installation method of sensors is limited to side-by-side arrangement in the same direction and cannot meet the requirements of opposite installation or vertical installation. Especially when the workpiece is in the detection blind area of the sensor, it is impossible to effectively locate the position and state change of the workpiece. Therefore, how to flexibly adapt to various installation methods while ensuring the detection accuracy has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this application is to overcome the above technical problems and provide a method and system for signal anti-interference between multi-ultrasonic ranging sensors A method for signal anti-interference between multi-ultrasonic ranging sensors includes the following steps: S1: Set the total number of anti-interference sensors N for N sensors through the host computer and assign unique consecutive identity ID identifiers (A0, A1... An); S2: Connect the RS485 interfaces of the sensors in parallel; S3: The host computer broadcasts and sends a start signal anti-interference instruction through RS485; S4: All sensors take the time when the instruction is received as the time zero point T0, and work independently in sequence according to the ID order within the time segments T0~T1, T1~T2…Tn~T(n+1), and repeat the polling after completing the cycle.

[0006] By adopting the above technical solution, multiple ultrasonic ranging sensors can achieve orderly time-segmented detection, effectively reducing the mutual interference problem caused by signal overlap. This method not only simplifies the installation requirements of the sensors, but also improves the flexibility and adaptability of the detection system, enabling the sensors to work stably in different scenarios (such as side-by-side in the same direction, facing each other, or vertically installed), significantly enhancing the reliability and accuracy of workpiece position detection.

[0007] Preferably, the calculation of the time interval T satisfies T≥2TOFmax, where TOFmax = 2LENmax / V; LENmax is the maximum ranging distance, and V is the propagation speed of ultrasonic waves in the air.

[0008] By adopting the above technical solution, it is ensured that each sensor completes the ranging task within the independent working period, reducing the problem of signal mutual interference when multiple sensors work simultaneously. The specific effects include: by accurately calculating the time interval T, it is ensured that the round-trip time of ultrasonic signals does not overlap, thereby improving the accuracy of ranging; at the same time, based on the parameter settings of the maximum ranging distance LENmax and the ultrasonic propagation speed V, the adaptability and reliability of the system are enhanced, suitable for application scenarios with different ranging ranges.

[0009] Preferably, the installation method includes at least one of side-by-side installation in the same direction, facing installation, or vertical installation, allowing detection blind area compensation and corner position detection.

[0010] By adopting the above technical solution, the installation method of the sensors is no longer limited to the traditional side-by-side installation in the same direction, and the side-by-side installation in the same direction, facing installation, or vertical installation can be selected according to the actual application scenario. Among them, side-by-side installation in the same direction can reduce the signal interference problem caused by insufficient installation spacing; facing installation can use the other sensor for compensation detection when the workpiece is in the detection blind area of one side sensor, ensuring the controllability of workpiece position change; vertical installation is suitable for detecting the position change of the workpiece at the corner, reducing the signal interference with sensors in the orthogonal direction. The flexible application of these three installation methods significantly enhances the adaptability and reliability of multi-sensor collaborative work, expanding the application scenarios of ultrasonic ranging sensors.

[0011] Preferably, the RS485 communication protocol supports parameter setting and detection value reading, and includes data interaction functions of analog output (0-10V / 4-20mA) and digital output (NPN / PNP).

[0012] By adopting the above technical solution, the sensor can utilize the RS485 communication protocol to achieve parameter setting and detection value reading functions, and support multiple data interaction modes. The specific effects include: 1) The analog output (0 - 10V / 4 - 20mA) can accurately reflect the distance change of the ranging detection value, providing continuous measurement data for users; 2) The digital output (NPN / PNP) intuitively indicates whether the workpiece exceeds the preset distance threshold through the level change, facilitating the quick judgment of the workpiece state. The above functions combined with the RS485 communication protocol enhance the flexibility and adaptability of the system, meeting the diverse requirements in different application scenarios.

[0013] Preferably, the total number N of the anti-interference sensors and the ID value are unique and continuous in each group of sensors, which is used to determine the working period sequence and the cycle period.

[0014] By adopting the above technical solution, it is ensured that the total number N of the anti-interference sensors and the ID value are unique and continuous in each group of sensors, so that the working period sequence of each sensor and the overall cycle period can be accurately determined, effectively reducing the problem of chaotic time period allocation caused by repeated or discontinuous IDs, ensuring the stable operation of the multi-sensor system in the time-sharing working mode, and enhancing the reliability and anti-interference ability of the system.

[0015] Preferably, when installed in an opposing manner, the sensors on both sides alternately detect and compensate for the blind area to ensure that the position change of the workpiece is in a controllable state.

[0016] By adopting the above technical solution, when the sensors on both sides are installed in an opposing manner, they can alternately detect the workpiece, effectively compensating for the detection blind area of the single-sided sensor. It ensures that even if the workpiece is in the blind area of one side sensor, the other side sensor can still normally detect its position change, thus realizing the full-process monitoring of the workpiece position change and improving the reliability and accuracy of the detection.

[0017] Preferably, in the vertical installation method, two groups of orthogonal sensors achieve position detection at the corner through time period isolation and do not interfere with each other.

[0018] By adopting the above technical solution, the vertical installation method enables two groups of orthogonal sensors to work independently in different time periods, thereby reducing the mutual interference of ultrasonic signals. The design of time period isolation ensures that the sensors can accurately detect the position change of the workpiece at the corner, improving the detection accuracy and reliability. Specifically, the vertical installation method combined with the time period isolation mechanism not only realizes the effective monitoring of the workpiece position in complex scenarios, but also expands the application range of the sensors, meeting the requirements of multi-angle and all-round detection.

[0019] Preferably, the host computer includes a PLC, a computer or an embedded controller, and the communication connection is achieved through an RS485 to USB repeater.

[0020] By adopting this technical solution, using a PLC, computer, or embedded controller as the host computer and establishing communication via an RS485-to-USB repeater, stable data exchange between the host computer and the sensors can be ensured. This solution significantly improves system operation convenience, allowing users to flexibly select different host computer devices to adapt to specific application scenarios. Furthermore, the introduction of the RS485-to-USB repeater effectively solves the debugging difficulties and parameter query inconvenience associated with traditional synchronization signal line connections, improving the maintainability and scalability of the entire system.

[0021] Preferably, during the synchronous startup phase, it is necessary to wait until all sensors are powered on and stable before sending a broadcast instruction to ensure the consistency of the zero time.

[0022] By adopting this technical solution, broadcast commands are sent after all sensors are powered on and stabilized during the synchronized startup phase. This ensures consistent zero-time timing and reduces time base deviations caused by incomplete initialization of individual sensors, thereby improving the accuracy and reliability of multi-sensor collaboration. This results in ensuring that each sensor accurately polls according to the predetermined time sequence, reducing signal interference caused by timing errors, and improving overall system stability and detection accuracy.

[0023] A multi-ultrasonic ranging signal anti-interference system, comprising: Setting module, communication module, control module, execution module and output module; The setting module is connected to each sensor via the RS485 interface and is used to assign sensor IDs and anti-interference totals; The communication module is composed of parallel RS485 buses, which physically connect the RS485 interfaces of all sensors to form a multi-node network; The control module is connected to the communication module via the RS485 bus, and sends a start signal to the entire network in the form of a host computer broadcast instruction; The execution module is embedded in each sensor. After receiving the timing instruction from the control module, it drives the sensor with the corresponding ID to work independently according to the time period of T0+(n*T)~T0+((n+1)*T) (n is the sensor ID number); The output module is integrated into each sensor hardware, electrically connected to the execution module through the analog interface and the switch interface, and simultaneously communicates with the communication module through the RS485 bus to achieve multi-mode output of the ranging value.

[0024] By adopting the above technical solution, multiple ultrasonic ranging sensors can achieve orderly time-division operation, effectively reducing the mutual interference problem caused by signal overlap. The system uses the RS485 interface for communication connection, ensuring that each sensor independently executes the ranging task according to the preset order, thereby improving the detection accuracy and reliability. In addition, the flexible installation method supports side-by-side installation in the same direction, opposite installation, and vertical installation, which not only solves the blind area detection problem in the traditional installation mode but also adapts to the diverse requirements in complex application scenarios, significantly enhancing the practicality and expandability of the system.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. By means of the time-division operation mode, the problem of signal mutual interference when multiple ultrasonic sensors work simultaneously is solved, allowing the sensors to operate stably at different installation spacings; 2. It supports various installation methods such as side-by-side installation in the same direction, opposite installation, and vertical installation, improving the flexibility of the system. Especially when installed oppositely, the blind area can be compensated by alternating detections of the sensors on both sides to ensure that the change in the position of the workpiece is controllable; 3. Parameter setting and data interaction are realized based on the RS485 communication protocol, which is convenient to operate and has strong anti-interference ability, meeting the application requirements in complex industrial environments. Description of the Drawings

[0026] Figure 1 is a flowchart of the method for preventing signal interference between multiple ultrasonic ranging sensors in the embodiment of the present application.

[0027] Figure 2 is a schematic diagram of the same-direction and side-by-side installation of sensors in the embodiment of the present application.

[0028] Figure 3 is a schematic diagram of the opposite installation of sensors in the embodiment of the present application.

[0029] Figure 4 is a schematic diagram of the vertical installation of sensors in the embodiment of the present application.

[0030] Figure 5 is a schematic diagram of the same-direction installation of multiple groups of sensors in the embodiment of the present application. Detailed Embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings. The described embodiments are only possible technical implementations of the present invention, not all possible implementations. Those skilled in the art can fully combine the embodiments of the present invention to obtain other embodiments without creative labor, and these embodiments are also within the protection scope of the present invention.

[0032] The inventors of the present application found that there are obvious limitations in the prior art when dealing with signal anti-interference of multiple ultrasonic ranging sensors of the same model. For this reason, the present application mainly adopts the following solutions, achieving the effect of solving the problem of signal mutual interference caused by multiple ultrasonic ranging sensors of the same type working together through the principle of working in different time periods. The following is a further detailed description of the present application.

[0033] A method for anti-interference of signals between multiple ultrasonic ranging sensors provided by an embodiment of the present application includes the following steps: S1: Set the total number N of anti-interference sensors for N sensors through the host computer, and assign unique consecutive identity ID identifiers (A0, A1... An).

[0034] Specifically, the host computer can be a device such as a PLC, a computer, or an embedded controller, and realizes the data interaction function with each sensor through the RS485 interface. The RS485 interface can implement parameter setting through alternative solutions such as a button + display module, IO-Link, etc., but RS485 has obvious advantages in terms of operation convenience, data intuitiveness, debugging difficulty, data transmission distance and rate, data anti-interference, and technology development difficulty. The ID value of each sensor must be unique and consecutive in each group of sensors, and the number of anti-interference sensors must also be the same in each sensor within the same group, ensuring the working time period sequence of the sensors and the time period of the entire cycle.

[0035] For further illustration, assume that a group contains 5 sensors, namely A0, A1, A2, A3, and A4. Then, it is necessary to set the total number N of anti-interference sensors in the host computer to 5, and at the same time assign ID identifiers in sequence. During this process, it is necessary to ensure that the ID of each sensor is unique and consecutive, for example, increasing sequentially from A0 to A4, reducing the occurrence of duplicates or skipped numbers. In addition, if the user needs to adjust the total number of sensors or reassign ID identifiers, the settings can be quickly completed through RS485 communication.

[0036] S2: Connect the RS485 interfaces of the sensors in parallel.

[0037] Specifically, the communication module is composed of a parallel RS485 bus, and physically connects the RS485 interfaces of all sensors to form a multi-node network. The communication module can use other communication methods, such as wireless communication protocols, etc., but RS485 is the preferred solution due to its stability and anti-interference ability. Parameter setting and detection value reading are realized through the RS485 bus, including data interaction functions of analog output (0 - 10V / 4 - 20mA) and digital output (NPN / PNP).

[0038] To ensure communication quality, it is recommended to minimize the length of the RS485 communication line during actual wiring and use shielded twisted pair wires to reduce external electromagnetic interference. In addition, if there are a large number of sensors, segmented wiring and the addition of repeaters can be considered to enhance the signal transmission distance and stability.

[0039] In addition, the installation methods of the sensors include at least one of side-by-side installation in the same direction, opposite installation, or vertical installation, allowing for detection blind spot compensation and corner position detection. When using opposite installation, the sensors on both sides alternately detect to compensate for the blind spots, ensuring that the change in the workpiece position is under control. In the vertical installation method, two groups of orthogonal sensors achieve corner position detection through time slot isolation without interfering with each other.

[0040] S3: The host computer broadcasts and sends a start signal anti-interference instruction through RS485.

[0041] Specifically, the control module is connected to the communication module through the RS485 bus, and sends a start signal to the entire network in the form of a host computer broadcast instruction. When using an RS485 to USB repeater to achieve communication connection, it can simplify on-site wiring and improve installation efficiency. During the synchronous start stage, a broadcast instruction needs to be sent after all sensors are powered on and stable to ensure the consistency of time zero.

[0042] In actual operation, it is recommended to wait at least 10 seconds after power-on to ensure that all sensors enter a stable working state before sending a broadcast instruction. If a certain sensor does not respond normally, its power supply voltage can be checked to see if it is normal, whether the RS485 communication line is reliably connected, and whether there are any faults in the sensor hardware.

[0043] S4: All sensors use the received instruction time as time zero T0, and work independently in sequential time periods T0~T1, T1~T2…Tn~T(n + 1) in ID order, and repeat polling after completing the cycle.

[0044] Specifically, the execution module is embedded inside each sensor. After receiving the timing instruction from the control module, it drives the sensor with the corresponding ID to work independently in the time period from T0+(n*T) to T0+((n + 1)*T) (n is the sensor ID number). The calculation of the time interval T satisfies T≥2TOFmax, where TOFmax = 2LENmax / V; LENmax is the maximum ranging distance, and V is the propagation speed of ultrasonic waves in the air. This time division method ensures that each sensor works in an independent time period, reducing signal overlap and interference.

[0045] Taking the maximum ranging distance LENmax of 3 meters as an example, the propagation speed V of ultrasonic waves in the air is approximately 340 m / s. Then TOFmax = 2×3 / 340 ≈ 0.0176 s. Therefore, the time interval T should be greater than or equal to 0.0352 s. According to different actual application scenarios, users can appropriately adjust the size of the time interval T as needed to balance the detection accuracy and the system response speed.

[0046] The implementation principle of this embodiment is as follows: By connecting the RS485 interfaces of all sensors in parallel, the host computer broadcasts and sends a start signal anti-interference instruction through RS485. All sensors take the time when the instruction is received as the time zero point T0, and work independently in sequence within sub-periods according to the ID order. After completing the cycle, polling is repeated, which solves the problem of signal interference caused by multiple ultrasonic ranging sensors of the same type working simultaneously, improves the detection accuracy and reliability, and at the same time allows flexible selection of the installation method of the sensors to meet the requirements of various complex application scenarios.

[0047] A multi-ultrasonic ranging signal anti-interference system provided by an embodiment of the present application includes a setting module, a communication module, a control module, an execution module, and an output module.

[0048] Specifically, the setting module is connected to each sensor through the RS485 interface and is used to allocate sensor IDs and the total number of anti-interference. The setting module can be implemented by means such as a button + display module, IO-Link, etc., but the RS485 interface has significant advantages in terms of operation convenience, data intuitiveness, etc.

[0049] To improve the user experience, it is recommended to add a friendly human-computer interaction interface to the setting module, such as graphically displaying information such as the working status and detection values of each sensor, to facilitate users to monitor and adjust system parameters in real time.

[0050] The communication module consists of a parallel RS485 bus, physically connecting the RS485 interfaces of all sensors to form a multi-node network. Other communication methods can be selected for the communication module, such as wireless communication protocols, but RS485 is the preferred solution due to its stability and anti-interference ability.

[0051] In an industrial environment, electromagnetic interference is relatively common. Therefore, it is recommended to add a filter circuit and an overvoltage protection device to the communication module to improve the anti-interference ability and safety of the system.

[0052] The control module is connected to the communication module through the RS485 bus and sends a start signal to the entire network in the form of a host computer broadcast instruction. The host computer can be a PLC, a computer, or an embedded controller, and the specific selection depends on the application scenario and user requirements.

[0053] To improve the compatibility and expandability of the system, it is recommended to reserve additional communication interfaces in the control module for future upgrades or connecting other devices.

[0054] The execution module is embedded inside each sensor. After receiving the timing instructions from the control module, it drives the sensor with the corresponding ID to work independently during the time period from T0+(n*T) to T0+((n+1)*T). The calculation of the time interval T satisfies T≥2TOFmax, where TOFmax = 2LENmax / V; LENmax is the maximum ranging distance, and V is the propagation speed of ultrasonic waves in the air.

[0055] To improve the detection accuracy, it is recommended to add a temperature compensation function to the execution module to correct the error of the ultrasonic wave propagation speed caused by the change of the ambient temperature.

[0056] The output module is integrated into the hardware of each sensor. It is electrically connected to the execution module through analog interfaces (such as 0 - 10V / 4 - 20mA) and digital interfaces (such as NPN / PNP), and at the same time, it exchanges data with the communication module through the RS485 bus to achieve multi-mode output of the ranging value. The output module can adopt replaceable features such as digital display screens and LED indicators to adapt to the visual habits and usage environments of different users.

[0057] To improve the flexibility of the output module, it is recommended to support the free switching of multiple output modes, such as analog output, digital output, and serial communication output, etc., to meet the needs of different users.

[0058] The implementation principle of this system is as follows: Through systematic design, each functional module is organically combined, ensuring the efficient implementation of the anti-interference function of multi-sensor signals. The flexibility and expandability of the system enable it to adapt to various complex industrial scenarios, significantly enhancing the application value of the ultrasonic ranging sensor.

[0059] The above are all the preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A method for anti-interference of signals between multiple ultrasonic ranging sensors, characterized in that, It includes the following steps: S1: Set the total number of anti-interference sensors N for N sensors through the host computer, and allocate unique consecutive identity ID tags (A0, A1... An); S2: Connect the RS485 interfaces of the sensors in parallel; S3: The host computer broadcasts and sends a start signal anti-interference instruction through RS485; S4: All sensors take the time when the instruction is received as the time zero point T0, and work independently in sequence within the time periods T0~T1, T1~T2... Tn~T(n + 1) according to the ID order, and repeat polling after completing the cycle.

2. The method according to claim 1, wherein: The calculation of the time interval T satisfies T≥2TOFmax, where TOFmax = 2LENmax / V; LENmax is the maximum ranging distance, and V is the propagation speed of ultrasonic waves in the air.

3. The method according to claim 1, wherein: The installation method includes at least one of side-by-side installation in the same direction, opposite installation, or vertical installation, allowing blind area compensation for detection and corner position detection.

4. The method according to claim 1, wherein: The RS485 communication protocol supports parameter setting and detection value reading, and includes data interaction functions of analog output (0 - 10V / 4 - 20mA) and digital output (NPN / PNP).

5. The method according to claim 1, wherein: The total number of anti-interference sensors N and the ID value are unique and continuous in each group of sensors, and are used to determine the working period order and cycle period.

6. The method according to claim 1, wherein: When using opposite installation, the sensors on both sides alternately detect and compensate for the blind area to ensure that the change in the workpiece position is in a controllable state.

7. The method according to claim 1, wherein: In the vertical installation method, two groups of orthogonal sensors achieve corner position detection through time period isolation and do not interfere with each other.

8. The method according to claim 1, wherein: The host computer includes a PLC, a computer, or an embedded controller, and realizes communication connection through an RS485 to USB repeater.

9. The method according to claim 1, wherein: In the synchronous startup stage, it is necessary to wait for all sensors to be powered on and stable before sending a broadcast instruction to ensure the consistency of the time zero point.

10. A multi-ultrasonic ranging signal anti-interference system, characterized in that It includes: A setting module, a communication module, a control module, an execution module, and an output module; The setting module is connected to each sensor through the RS485 interface and is used to allocate sensor IDs and the total number of anti-interference; The communication module consists of a parallel RS485 bus, and physically connects the RS485 interfaces of all sensors to form a multi-node network; The control module is connected to the communication module through the RS485 bus, and sends a start signal to the entire network in the form of a host computer broadcast instruction; The execution module is embedded inside each sensor. After receiving the timing instruction from the control module, it drives the sensor corresponding to the ID to work independently in the time period T0+(n*T)~T0+((n + 1)*T) (n is the sensor ID serial number); The output module is integrated into each sensor hardware, and is electrically connected to the execution module through analog interfaces and digital interfaces. At the same time, it exchanges data with the communication module through the RS485 bus to achieve multi-mode output of ranging values.

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