Proximity switch distance measurement method and system based on combination of inductance and capacitance

Abstract

The application discloses a proximity switch distance measurement method and system based on the combination of inductance and capacitance, relates to the technical field of distance measurement, and determines the material information of a moving object by sending electromagnetic signals and electric field signals to the surroundings; and identifies and adjusts the measurement distance weight values corresponding to the inductive sensor and the capacitive sensor when the current moving object is used for distance measurement; obtains the environmental temperature and humidity where the current moving object is located, and adjusts the frequencies of the inductive sensor and the capacitive sensor according to the environmental temperature and humidity where the current moving object is located; and completes distance measurement according to the inductive sensor and the capacitive sensor after frequency adjustment and the measurement distance weight values corresponding to the inductive sensor and the capacitive sensor. In this way, the distance measurement of the moving object is performed by combining inductance and capacitance, so that the measurement accuracy is relatively high, and consistency and reliability can be ensured in complex actual application scenarios.

Description

Technical Field

[0001] The present invention relates to the technical field of distance measurement, and in particular to a proximity switch distance measurement method and system based on a combination of inductance and capacitance. Background Art

[0002] Proximity switches typically use inductive or capacitive sensors to measure distance. Inductive proximity switches generate an electromagnetic field, using the conductivity of metal objects to influence the field's intensity. When a metal object approaches, the electromagnetic field of the inductive sensor changes, causing the sensor's output signal to change, thereby determining the object's presence and distance. Capacitive proximity switches, on the other hand, generate an electric field and rely on the effect of an object (especially non-metallic objects) on this field to detect approaching objects. Capacitive sensors operate by measuring the object's effect on the electric field to calculate the distance between the object and the sensor.

[0003] However, traditional proximity switch distance measurement methods often rely solely on a single inductive or capacitive sensor to measure the distance of moving objects, resulting in low measurement accuracy. In addition, traditional methods have low measurement accuracy and stability due to environmental changes or the diversity of object materials, making it difficult to ensure consistency and reliability in complex practical application scenarios. Summary of the Invention

[0004] The purpose of the present invention is to solve the above-mentioned problems and provide a proximity switch distance measurement method and system based on a combination of inductance and capacitance.

[0005] In a first aspect of the present invention, a proximity switch distance measurement method based on a combination of inductance and capacitance is first proposed, the method comprising:

[0006] The control modules of the inductive sensor and the capacitive sensor are activated to detect the surrounding electromagnetic signals and electric field signals in real time, send electromagnetic signals and electric field signals to the surroundings, and determine the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals;

[0007] Based on the material information of the moving object, identify and adjust the measurement distance weight values ​​corresponding to the inductive sensor and capacitive sensor when measuring the distance of the current moving object;

[0008] Obtain the current ambient temperature and humidity of the moving object, and adjust the frequency of the inductive sensor and the capacitive sensor according to the current ambient temperature and humidity of the moving object;

[0009] The distance measurement is completed according to the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor after the frequency adjustment.

[0010] Optionally, the step of determining the material information of the moving object according to the reflection signals of the electromagnetic signals and the electric field signals is:

[0011] extracting the reflection signals of the electromagnetic signals from the inductive sensors as the first signals and extracting the reflection signals of the electric field signals from the capacitive sensors as the second signals;

[0012] preprocessing the first signals and the second signals, and calculating based on the preprocessed first signals and the second signals, and obtaining the time from the emission to the return of the first signals and the second signals to the corresponding inductive sensors and capacitive sensors, recorded as the first delay time and the second delay time;

[0013] calculating the amplitude integrals of the first signals and the second signals, and recording the results of the integrals as the first signal intensity value and the second signal intensity value respectively;

[0014] comparing the first signal intensity value and the second signal intensity value, comparing the first delay time and the second delay time, if the first signal intensity value is greater than the second signal intensity value and the first delay time is less than the second delay time, the material information of the corresponding moving object is more likely to be metal;

[0015] if the first signal intensity value is less than the second signal intensity value and the first delay time is greater than the second delay time, the material information of the corresponding moving object is more likely to be non-metal;

[0016] if the first signal intensity value is equal to the second signal intensity value and the first delay time is equal to the second delay time, the material information of the corresponding moving object is equal in probability of being non-metal and metal.

[0017] Optionally, based on the material information of the moving object, the step of identifying and adjusting the measurement distance weight values of the inductive sensors and the capacitive sensors when the current moving object is performing distance measurement is:

[0018] when the material information of the moving object is equal in probability of being non-metal and metal, the measurement distance weight values of the inductive sensors and the capacitive sensors are both recorded as 0.5;

[0019] when the material information of the moving object is more likely to be metal or the material information of the moving object is more likely to be metal, the sum of the first signal intensity value and the second signal intensity value is calculated as the overall signal intensity value;

[0020] the first signal intensity value and the second signal intensity value are respectively divided by the overall signal intensity value to obtain the corresponding signal intensity weight values;

[0021] Calculate the sum of the first delay time and the second delay time as the overall delay time; divide the first delay time and the second delay time by the overall delay time respectively to obtain corresponding delay time weight values;

[0022] The average of the corresponding signal strength weight value and the corresponding delay time weight value is used as the measurement distance weight value corresponding to the inductive sensor and the capacitive sensor.

[0023] Optionally, the steps of obtaining the current ambient temperature and humidity of the moving object and adjusting the frequencies of the inductive sensor and the capacitive sensor according to the current ambient temperature and humidity of the moving object are as follows:

[0024] The time when the electromagnetic signal and the electric field signal are sent is taken as the starting time, and the time from the starting time to the present is recorded as the time interval; the temperature and humidity of the environment in which the moving object is located during the time interval are obtained, and the average temperature and average humidity are calculated;

[0025] Compare the average temperature and average humidity with the preset standard temperature and preset standard humidity respectively. If the average temperature is greater than the preset standard temperature, reduce the frequency of the inductive sensor and the capacitive sensor;

[0026] If the average humidity is greater than the preset standard humidity, the frequency of the capacitive sensor is reduced.

[0027] Optionally, the steps of completing the distance measurement according to the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor after frequency adjustment are as follows:

[0028] The frequency-adjusted inductive sensors and capacitive sensors send electromagnetic signals and electric field signals to the surroundings, and receive reflected signals of the electromagnetic signals and electric field signals;

[0029] Calculate the distance value corresponding to the inductive sensor. The calculation formula is: , where is the distance value corresponding to the inductive sensor, is the propagation speed of electromagnetic waves, , is the round trip time of the electromagnetic signal;

[0030] Calculate the distance value corresponding to the capacitive sensor. The calculation formula is: , where is the distance value corresponding to the capacitive sensor, is the round trip time of the electric field signal, is the propagation speed of the electric field signal, and the calculation formula is: , where is the propagation speed of electromagnetic waves, is the relative dielectric constant of the medium 1;

[0031] Multiply the distance value corresponding to the inductive sensor by the corresponding distance weight value to obtain the first distance, multiply the distance value corresponding to the capacitive sensor by the corresponding distance weight value to obtain the second distance, add the first distance and the second distance, divide the result of the addition by the sum of the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor to obtain the final distance, and complete the distance measurement.

[0032] In a second aspect of the present invention, a proximity switch distance measurement system based on a combination of inductance and capacitance is proposed, the system comprising:

[0033] Material information determination module: The control modules of the inductive sensor and the capacitive sensor are activated to detect the surrounding electromagnetic signals and electric field signals in real time, send electromagnetic signals and electric field signals to the surroundings, and determine the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals;

[0034] Distance weight module: Based on the material information of the moving object, it identifies and adjusts the distance weight values ​​corresponding to the inductive sensor and the capacitive sensor when measuring the distance of the current moving object;

[0035] Adjustment module: obtains the ambient temperature and humidity of the current moving object, and adjusts the frequency of the inductive sensor and the capacitive sensor according to the ambient temperature and humidity of the current moving object;

[0036] Distance measurement module: completes distance measurement based on the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor after frequency adjustment.

[0037] Optionally, the material information determination module includes:

[0038] Signal extraction module: extracts the reflected signal of the electromagnetic signal from the inductive sensor as the first signal, and extracts the reflected signal of the electric field signal from the capacitive sensor as the second signal;

[0039] Marking module: preprocesses the first signal and the second signal, performs calculations based on the preprocessed first signal and the second signal, and obtains the time from the first signal and the second signal being transmitted to the time when they return to the corresponding inductive sensor and capacitive sensor, which are recorded as the first delay time and the second delay time;

[0040] Signal strength module: calculates the amplitude integral of the first signal and the second signal, and records the integral results as the first signal strength value and the second signal strength value respectively;

[0041] A first comparison module compares the first signal strength value with the second signal strength value, and compares the first delay time with the second delay time. If the first signal strength value is greater than the second signal strength value and the first delay time is less than the second delay time, the corresponding moving object is likely to be metal.

[0042] Second comparison module: if the first signal strength value is less than the second signal strength value and the first delay time is greater than the second delay time, then the probability that the material information of the corresponding moving object is non-metal is relatively high;

[0043] Third comparison module: If the first signal strength value is equal to the second signal strength value and the first delay time is equal to the second delay time, the probability that the material information of the corresponding moving object is non-metal and metal is equal.

[0044] Optionally, the distance weight module includes:

[0045] First distance weight value: When the probability of the moving object's material information being non-metal and metal is equal, the measurement distance weight values ​​corresponding to the inductive sensor and the capacitive sensor are both recorded as 0.5;

[0046] Overall signal strength module: when the probability that the material information of the moving object is metal is high or the probability that the material information of the moving object is metal is high, the sum of the first signal strength value and the second signal strength value is calculated as the overall signal strength value;

[0047] Signal strength weight module: divides the first signal strength value and the second signal strength value by the overall signal strength value to obtain corresponding signal strength weight values;

[0048] Delay time weight module: calculates the sum of the first delay time and the second delay time as the overall delay time; divides the first delay time and the second delay time by the overall delay time respectively to obtain the corresponding delay time weight value;

[0049] The second distance weight module uses the average of the corresponding signal strength weight value and the corresponding delay time weight value as the measurement distance weight value corresponding to the inductive sensor and the capacitive sensor.

[0050] Optionally, the adjustment module includes:

[0051] Temperature and humidity calculation module: The time when the electromagnetic signal and electric field signal are sent is taken as the starting time, and the time from the starting time to the current time is recorded as the time interval; the temperature and humidity of the environment in which the moving object is located within the time interval are obtained, and the average temperature and average humidity are calculated;

[0052] The first adjustment module compares the average temperature and average humidity with the preset standard temperature and preset standard humidity respectively. If the average temperature is greater than the preset standard temperature, the frequency of the inductive sensor and the capacitive sensor is reduced;

[0053] The second adjustment module: if the average humidity is greater than the preset standard humidity, the frequency of the capacitive sensor is reduced.

[0054] Optionally, the distance measurement module includes:

[0055] Retransmitter module: The frequency-adjusted inductive and capacitive sensors send electromagnetic and electric field signals to the surroundings, and receive reflected signals of the electromagnetic and electric field signals.

[0056] The first calculation module: calculates the distance value corresponding to the inductive sensor. The calculation formula is: , where is the distance value corresponding to the inductive sensor, is the propagation speed of electromagnetic waves, , is the round trip time of the electromagnetic signal;

[0057] The second calculation module calculates the distance value corresponding to the capacitive sensor. The calculation formula is: , where is the distance value corresponding to the capacitive sensor, is the round trip time of the electric field signal, is the propagation speed of the electric field signal, and the calculation formula is: , where is the propagation speed of electromagnetic waves, is the relative dielectric constant of the medium 1;

[0058] The third calculation module: multiplies the distance value corresponding to the inductive sensor by the corresponding distance weight value to obtain the first distance, multiplies the distance value corresponding to the capacitive sensor by the corresponding distance weight value to obtain the second distance, adds the first distance and the second distance, divides the result of the addition by the sum of the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor to obtain the final distance, and completes the distance measurement.

[0059] Beneficial effects of the present invention:

[0060] The present invention proposes a proximity switch distance measurement method and system based on the combination of inductance and capacitance, which sends electromagnetic signals and electric field signals to the surroundings and determines the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals; based on the material information of the moving object, identifies and adjusts the measurement distance weight values ​​corresponding to the inductance sensor and the capacitance sensor when the current moving object is measured; obtains the temperature and humidity of the current environment in which the moving object is located, and adjusts the frequency of the inductance sensor and the capacitance sensor according to the current environment in which the moving object is located; completes the distance measurement based on the inductance sensor and capacitance sensor after adjusting the frequency and the measurement distance weight values ​​corresponding to the inductance sensor and the capacitance sensor. In this way, by combining inductance and capacitance to measure the distance of the moving object, the measurement accuracy is higher; in addition, the frequency of the inductance sensor and the capacitance sensor can be adjusted according to environmental changes or the diversity of the object material for distance measurement, so that the measurement accuracy and stability are higher, and consistency and reliability can be guaranteed in complex practical application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The present invention will be further described below with reference to the accompanying drawings.

[0062] Figure 1 The figure is a flow chart of a proximity switch distance measurement method based on a combination of inductance and capacitance;

[0063] Figure 2 The framework diagram of the proximity switch distance measurement system based on the combination of inductance and capacitance. DETAILED DESCRIPTION

[0064] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0065] The embodiment of the present invention provides a proximity switch distance measurement method based on the combination of inductance and capacitance. Figure 1 , Figure 1 A flow chart of a proximity switch distance measurement method based on a combination of inductance and capacitance provided in an embodiment of the present invention. The method comprises the following steps:

[0066] The control modules of the inductive sensor and the capacitive sensor are activated to detect the surrounding electromagnetic signals and electric field signals in real time, send electromagnetic signals and electric field signals to the surroundings, and determine the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals;

[0067] Based on the material information of the moving object, identify and adjust the measurement distance weight values ​​corresponding to the inductive sensor and capacitive sensor when measuring the distance of the current moving object;

[0068] Obtain the current ambient temperature and humidity of the moving object, and adjust the frequency of the inductive sensor and the capacitive sensor according to the current ambient temperature and humidity of the moving object;

[0069] The distance measurement is completed according to the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor after the frequency adjustment.

[0070] According to the proximity switch distance measurement method based on the combination of inductance and capacitance provided by the embodiment of the present invention, the distance measurement of a moving object is performed by combining inductance and capacitance in the above manner, thereby achieving high measurement accuracy. In addition, the frequency of the inductive sensor and the capacitive sensor can be adjusted according to environmental changes or the diversity of the object material for distance measurement, resulting in high measurement accuracy and stability, and ensuring consistency and reliability in complex practical application scenarios.

[0071] In one embodiment, the control modules of the inductive sensor and the capacitive sensor are activated to detect the surrounding electromagnetic signals and electric field signals in real time, transmit the electromagnetic signals and electric field signals to the surroundings, and determine the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals;

[0072] The step of determining the material information of the moving object based on the reflected signals of the electromagnetic signal and the electric field signal is as follows:

[0073] Extracting a reflected signal of the electromagnetic signal from the inductive sensor as a first signal, and extracting a reflected signal of the electric field signal from the capacitive sensor as a second signal;

[0074] Preprocess the first signal and the second signal, perform calculations based on the preprocessed first signal and the second signal, and obtain the time from when the first signal and the second signal are transmitted to when they return to the corresponding inductive sensor and capacitive sensor, which are recorded as the first delay time and the second delay time;

[0075] Calculating the amplitude integrals of the first signal and the second signal, and recording the integral results as the first signal strength value and the second signal strength value, respectively;

[0076] Comparing the first signal strength value with the second signal strength value, and comparing the first delay time with the second delay time, if the first signal strength value is greater than the second signal strength value and the first delay time is less than the second delay time, then the corresponding material information of the moving object is likely to be metal;

[0077] If the first signal strength value is less than the second signal strength value and the first delay time is greater than the second delay time, the probability that the material information of the corresponding moving object is non-metal is relatively high;

[0078] If the first signal strength value is equal to the second signal strength value and the first delay time is equal to the second delay time, the probability that the material information of the corresponding moving object is non-metal and metal is equal.

[0079] It's important to note that once the control modules of the inductive and capacitive sensors are activated, they detect surrounding electromagnetic and electric field signals in real time and transmit these signals to the surrounding environment. Inductive sensors detect metallic properties of objects through the reflection of electromagnetic signals, while capacitive sensors detect non-metallic properties through the reflection of electric field signals. By analyzing the reflection characteristics of electromagnetic and electric field signals, such as signal strength and delay, the material of the moving object can be inferred. For example, for metallic objects, electromagnetic signals typically reflect strongly and have a short delay, while electric field signals reflect relatively weakly. Conversely, for non-metallic objects, electric field signals reflect strongly and electromagnetic signals reflect weakly. This allows the system to accurately determine the object's material and adjust the sensor's measurement parameters to improve measurement accuracy and stability. For example, when approaching a metallic object, the system prioritizes the inductive sensor's measurement capabilities, ensuring more accurate distance data in the presence of metallic objects.

[0080] It's important to note that analyzing the reflected signals from inductive and capacitive sensors can effectively distinguish objects of different materials. For example, when the system detects an object, the electromagnetic signal's reflection intensity is typically high and the return time is short, indicating that the object is likely metal. For example, when detecting a steel plate, the electromagnetic reflection signal received by the inductive sensor will show strong reflection and a short signal delay. This is because metal reflects electromagnetic waves strongly and signals propagate quickly. In contrast, when the system detects a plastic object, the electric field signal's reflection intensity is often high, while the electromagnetic signal's reflection is weaker, and the signal delay is longer. This is because plastic reflects electromagnetic waves less strongly, but has a more pronounced effect on the electric field signal, and signals propagate more slowly. In this way, the system can accurately determine the object's material and adjust the sensor's measurement parameters based on the material's characteristics, improving the accuracy and stability of distance measurement. In complex environments, this identification ensures that the sensor works effectively with a variety of objects and materials, avoiding errors.

[0081] In one embodiment, based on the material information of the moving object, the steps of identifying and adjusting the distance weight values ​​corresponding to the inductive sensor and the capacitive sensor when the current moving object is measured for distance are as follows:

[0082] When the probability of the material information of the moving object being non-metal and metal is equal, the measurement distance weight values corresponding to the inductive sensor and the capacitive sensor are recorded as 0.5;

[0083] When the probability of the material information of the moving object being metal is relatively large or the probability of the material information of the moving object being metal is relatively large, the sum of the first signal strength value and the second signal strength value is calculated as the overall signal strength value;

[0084] The first signal strength value and the second signal strength value are respectively divided by the overall signal strength value to obtain the corresponding signal strength weight values;

[0085] The sum of the first delay time and the second delay time is calculated as the overall delay time; the first delay time and the second delay time are respectively divided by the overall delay time to obtain the corresponding delay time weight values;

[0086] The average of the corresponding signal strength weight values and the corresponding delay time weight values is taken as the measurement distance weight values corresponding to the inductive sensor and the capacitive sensor.

[0087] It should be noted that in actual application, based on the material information of the object, the measurement distance weight values of the inductive sensor and the capacitive sensor will be dynamically adjusted according to the different materials of the object. For example, when the system detects that the material information of the object is metal, the reflection of the electromagnetic signal will be strong, the signal strength will be large, and the return time will be short. At this time, the weight value of the inductive sensor will be higher, indicating that the inductive sensor contributes more to distance measurement, because the metal object is more sensitive to the response of the electromagnetic signal. On the contrary, the weight value of the capacitive sensor will be lower, because its reaction is not as sensitive to the change of the metal object as the inductive sensor.

[0088] It should be noted that, for example, assuming that the system detects a metal box, the signal strength returned by the inductive sensor is 0.8, the signal strength returned by the capacitive sensor is 0.2, the delay time of the inductive sensor is 0.05 seconds, and the delay time of the capacitive sensor is 0.15 seconds. In this case, the signal strength of the inductive sensor dominates, and the weight value will be more biased towards the inductive sensor, while the influence of the capacitive sensor is relatively small. The calculation process may result in a weight value of 0.75 for the inductive sensor and a weight value of 0.25 for the capacitive sensor; for another example, assuming that the system detects a plastic object, the signal strength is relatively balanced, and the signal strengths of the inductive and capacitive sensors are not much different. The signal strength of the inductive sensor is 0.5, the signal strength of the capacitive sensor is 0.5, and the delay times are also close to equal. At this time, since the differences between the two in reflection signal strength and delay time are small, the system sets the measurement distance weight values of the inductive sensor and the capacitive sensor to be equal, for example, each is 0.5, to ensure that the two sensors have balanced effects in distance measurement.

[0089] In one implementation, the dynamic adjustment of the weight value enables the system to optimize the accuracy of distance measurement according to the material characteristics when processing objects of different materials, thereby improving the precision and stability of the measurement.

[0090] In one embodiment, the steps of obtaining the current ambient temperature and humidity of the moving object and adjusting the frequencies of the inductive sensor and the capacitive sensor according to the current ambient temperature and humidity of the moving object are as follows:

[0091] The time when the electromagnetic signal and the electric field signal are sent is taken as the starting time, and the time from the starting time to the present is recorded as the time interval; the temperature and humidity of the environment in which the moving object is located during the time interval are obtained, and the average temperature and average humidity are calculated;

[0092] Compare the average temperature and average humidity with the preset standard temperature and preset standard humidity respectively. If the average temperature is greater than the preset standard temperature, reduce the frequency of the inductive sensor and the capacitive sensor;

[0093] If the average humidity is greater than the preset standard humidity, the frequency of the capacitive sensor is reduced.

[0094] It should be noted that the period from the start time to the current time is called a time interval. During this time interval, the ambient temperature and humidity are continuously monitored, and the data is collected and recorded. This data is read in real time by the built-in temperature and humidity sensor or other environmental monitoring equipment. The average temperature and humidity for this time interval are calculated. These two values ​​reflect the current temperature and humidity conditions of the environment. For example, suppose that within a 5-minute time interval, the temperature is 22°C, 23°C, and 24°C, and the humidity is 50%, 55%, and 53%, respectively. The average temperature for this time period is (22+23+24) / 3 = 23°C, and the average humidity is (50+55+53) / 3 = 52.67%. The calculated average temperature and humidity are compared with the preset standard temperature and humidity. The preset standard temperature and humidity are ideal values ​​set based on normal operating conditions. For example, suppose the preset standard temperature is 22°C and the standard humidity is 50%. By comparing the current average temperature and humidity with these standard values, it is determined whether the current environment exceeds the ideal operating range. If the average temperature exceeds the preset reference temperature (i.e., the ambient temperature is too high), the propagation speed of electromagnetic waves may increase, affecting the measurement accuracy of inductive and capacitive sensors. Therefore, the frequency needs to be reduced to accommodate this change. Reducing the frequency effectively reduces errors caused by excessive signal propagation in high-temperature environments, ensuring that the signal can fully propagate across the target surface, thereby improving measurement accuracy. For example, if the preset reference temperature is 22°C and the current average temperature is 25°C (high), to compensate for this temperature increase, the operating frequency of the inductive and capacitive sensors will be reduced, perhaps from 100MHz to 90MHz. This ensures more stable signal propagation and avoids signal distortion caused by excessive propagation speed in high temperatures. If the average humidity exceeds the preset reference temperature (i.e., the ambient humidity is too high), the high humidity may cause the dielectric constant of the air to change, affecting the capacitance measurement characteristics. In high-humidity environments, the capacitance sensor's response may become more sensitive, so the frequency needs to be appropriately reduced. Reducing the frequency can reduce the signal deviation caused by high humidity, thereby improving measurement accuracy. Assume the preset standard humidity is 50%, while the current average humidity is 60% (high). To compensate for the increased humidity, the capacitive sensor frequency can be reduced, perhaps from 100MHz to 95MHz. This ensures more stable operation of the capacitive sensor and avoids measurement errors caused by excessive humidity. By collecting and analyzing temperature and humidity data in real time, once an appropriate adjustment solution is obtained, the adjusted frequency setting is immediately applied to the control modules of the inductive and capacitive sensors. At this point, the sensor's operating frequency automatically adjusts to the current temperature and humidity conditions to ensure optimal measurement accuracy.The adjusted frequency immediately affects the sensor's response characteristics, and thus the accuracy and stability of the measurement results. Assume the preset standard temperature is 22°C and the standard humidity is 50%. In actual application, assume the temperature of the moving object is 25°C and the humidity is 60%. After analysis, the average temperature is calculated to be 25°C and the average humidity is 60%. Because the current temperature is higher than the standard, the frequency of the inductive and capacitive sensors is reduced (for example, to 90MHz). Furthermore, because the humidity is also higher than the standard, the frequency of the capacitive sensor is specifically reduced (for example, to 95MHz). This allows the sensor to provide more accurate distance measurements under the current environmental conditions.

[0095] It's important to note that when the temperature is below a preset reference temperature, the frequency of the inductive sensor remains unchanged. This is because temperature changes have little impact on inductive sensors, and low temperatures generally don't significantly alter their operating characteristics. However, the frequency of the capacitive sensor needs to be reduced because the dielectric constant of air can increase at low temperatures, slowing the propagation of electric field signals. To accommodate this change and reduce measurement errors, the frequency of the capacitive sensor needs to be lowered. This adjustment ensures that the capacitive sensor can still accurately respond to changes in the electric field in low-temperature conditions, thereby maintaining measurement accuracy.

[0096] It should be noted that when the temperature is below the preset standard, the operating frequency of the inductive sensor generally does not need to be adjusted. This is because electromagnetic waves propagate slower in low temperatures, and frequency changes have less impact on the inductive sensor's measurement accuracy. Therefore, the frequency of the inductive sensor is kept constant to ensure its stability and accuracy. However, when the humidity exceeds the preset standard, the increased humidity causes changes in the dielectric constant of the air, which in turn affects the performance of the capacitive sensor. High humidity increases the number of water molecules in the air, which in turn changes the propagation characteristics of the electric field, making the capacitive sensor's response more sensitive. To avoid measurement errors caused by excessive humidity, the capacitive sensor's frequency is reduced to mitigate its overly sensitive response, thereby improving measurement stability and accuracy. This adjustment allows the capacitive sensor to better adapt to changes in humidity.

[0097] In one implementation, through this series of steps, the operating frequency of the sensor can be intelligently adjusted to ensure high-precision measurement performance under different environmental conditions.

[0098] In one embodiment, the steps of completing distance measurement according to the inductive sensor and the capacitive sensor after frequency adjustment and the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor are as follows:

[0099] The inductance sensor and the capacitance sensor send electromagnetic signals and electric field signals to the surroundings and receive reflected signals of the electromagnetic signals and the electric field signals after frequency adjustment;

[0100] The distance value corresponding to the inductance sensor is calculated according to the following formula: , wherein, is the distance value corresponding to the inductance sensor, is the propagation speed of electromagnetic waves (usually the speed of light ), and is the round-trip time of the electromagnetic signals;

[0101] It should be noted that the division by 2 is because the signal propagation is not one-way but round-trip;

[0102] The distance value corresponding to the capacitance sensor is calculated according to the following formula: , wherein, is the distance value corresponding to the capacitance sensor, is the round-trip time of the electric field signals, is the propagation speed of the electric field signals, which is calculated according to the following formula: , wherein, is the propagation speed of electromagnetic waves (usually the speed of light ), is the relative permittivity of the medium, which represents the degree of influence of the medium on the electric field, and for air is approximately 1;

[0103] The distance value corresponding to the inductance sensor is multiplied by the corresponding distance weight value to obtain a first distance, the distance value corresponding to the capacitance sensor is multiplied by the corresponding distance weight value to obtain a second distance, the first distance and the second distance are added, and the sum is divided by the sum of the measurement distance weight values corresponding to the inductance sensor and the capacitance sensor to obtain a final distance, thereby completing the distance measurement.

[0104] It should be noted that the relative permittivity of air is approximately 1. Since the electromagnetic wave propagation characteristics of air are similar to those of vacuum, the speed of the electric field signals in air is basically the same as the speed of light. Water: The relative permittivity of water also means that when capacitance measurement is performed in a water environment, the signal propagation speed and the measurement accuracy of the sensor will be significantly affected. Glass: The relative permittivity of glass is approximately 4-7, depending on the type of glass. The relative permittivity of glass is lower than that of air and water, but is still higher than 1, which will cause the propagation speed of the electric field signals in glass to slow down, but faster than in water. Plastic: The relative permittivity of common plastics (such as polyethylene, polypropylene, etc.) Usually between 2 and 3. The relative dielectric constant of plastic is higher than that of air, but lower than that of water and glass, so the propagation speed of electric field signals is moderate. Therefore, the relative dielectric constant of the medium is This directly affects the response of capacitive sensors in different environments. When measuring distance, the propagation speed needs to be adjusted according to the medium to ensure accurate calculation of the distance to the object.

[0105] It's important to note that in practical applications, combining the measurements of the inductive and capacitive sensors to calculate the final distance is a crucial step. For example, suppose in a certain measurement scenario, the inductive sensor measures a distance of 3 meters, while the capacitive sensor measures a distance of 2.5 meters. Based on this, we can introduce weights for each measurement to optimize the distance calculation. For example, a weight of 0.6 for the inductive sensor and 0.4 for the capacitive sensor indicates that the inductive sensor is more reliable in this environment. Based on these weights, we first multiply the inductive sensor's distance (3 meters) by its weight (0.6) to obtain 1.8 meters. Then, we multiply the capacitive sensor's distance (2.5 meters) by its weight (0.4) to obtain 1 meter. Finally, we add the two weighted results (1.8 meters + 1 meter = 2.8 meters) and divide them by the sum of the two weights (0.6 + 0.4 = 1) to obtain the final distance of 2.8 meters. This method combines the measurement results and weights of inductive and capacitive sensors to make the final distance measurement more accurate and reliable, especially in complex measurement environments. It can fully consider the advantages and adaptability of different sensors and thus provide more precise results.

[0106] Based on the same inventive concept, the present invention also provides a proximity switch distance measurement system based on a combination of inductance and capacitance. Figure 2 , Figure 2 A framework diagram of a proximity switch distance measurement system based on a combination of inductance and capacitance provided in an embodiment of the present invention, the system comprising:

[0107] Material information determination module: The control modules of the inductive sensor and the capacitive sensor are activated to detect the surrounding electromagnetic signals and electric field signals in real time, send electromagnetic signals and electric field signals to the surroundings, and determine the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals;

[0108] Distance weight module: Based on the material information of the moving object, it identifies and adjusts the distance weight values ​​corresponding to the inductive sensor and the capacitive sensor when measuring the distance of the current moving object;

[0109] Adjustment module: obtains the ambient temperature and humidity of the current moving object, and adjusts the frequency of the inductive sensor and the capacitive sensor according to the ambient temperature and humidity of the current moving object;

[0110] Distance measurement module: completes distance measurement based on the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor after frequency adjustment.

[0111] The proximity switch distance measurement system based on a combination of inductance and capacitance provided by an embodiment of the present invention uses the above-described method to measure the distance of a moving object by combining inductance and capacitance, thereby achieving high measurement accuracy. Furthermore, the frequencies of the inductive and capacitive sensors can be adjusted to measure distance based on environmental changes or the diversity of object materials, resulting in high measurement accuracy and stability, ensuring consistency and reliability in complex practical application scenarios.

[0112] In one embodiment, the signal extraction module extracts a reflection signal of the electromagnetic signal from the inductive sensor as the first signal, and extracts a reflection signal of the electric field signal from the capacitive sensor as the second signal;

[0113] Marking module: preprocesses the first signal and the second signal, performs calculations based on the preprocessed first signal and the second signal, and obtains the time from the first signal and the second signal being transmitted to the time when they return to the corresponding inductive sensor and capacitive sensor, which are recorded as the first delay time and the second delay time;

[0114] Signal strength module: calculates the amplitude integral of the first signal and the second signal, and records the integral results as the first signal strength value and the second signal strength value respectively;

[0115] A first comparison module compares the first signal strength value with the second signal strength value, and compares the first delay time with the second delay time. If the first signal strength value is greater than the second signal strength value and the first delay time is less than the second delay time, the corresponding moving object is likely to be metal.

[0116] Second comparison module: if the first signal strength value is less than the second signal strength value and the first delay time is greater than the second delay time, then the probability that the material information of the corresponding moving object is non-metal is relatively high;

[0117] Third comparison module: If the first signal strength value is equal to the second signal strength value and the first delay time is equal to the second delay time, the probability that the material information of the corresponding moving object is non-metal and metal is equal.

[0118] In one embodiment, the distance weight module includes:

[0119] First distance weight value: When the probability of the moving object's material information being non-metal and metal is equal, the measurement distance weight values ​​corresponding to the inductive sensor and the capacitive sensor are both recorded as 0.5;

[0120] Overall signal strength module: when the probability that the material information of the moving object is metal is high or the probability that the material information of the moving object is metal is high, the sum of the first signal strength value and the second signal strength value is calculated as the overall signal strength value;

[0121] Signal strength weight module: divides the first signal strength value and the second signal strength value by the overall signal strength value to obtain corresponding signal strength weight values;

[0122] Delay time weight module: calculates the sum of the first delay time and the second delay time as the overall delay time; divides the first delay time and the second delay time by the overall delay time respectively to obtain the corresponding delay time weight value;

[0123] The second distance weight module uses the average of the corresponding signal strength weight value and the corresponding delay time weight value as the measurement distance weight value corresponding to the inductive sensor and the capacitive sensor.

[0124] In one embodiment, the adjustment module includes:

[0125] Temperature and humidity calculation module: The time when the electromagnetic signal and electric field signal are sent is taken as the starting time, and the time from the starting time to the current time is recorded as the time interval; the temperature and humidity of the environment in which the moving object is located within the time interval are obtained, and the average temperature and average humidity are calculated;

[0126] The first adjustment module compares the average temperature and average humidity with the preset standard temperature and preset standard humidity respectively. If the average temperature is greater than the preset standard temperature, the frequency of the inductive sensor and the capacitive sensor is reduced;

[0127] The second adjustment module: if the average humidity is greater than the preset standard humidity, the frequency of the capacitive sensor is reduced.

[0128] In one embodiment, the distance measurement module includes:

[0129] Retransmitter module: The frequency-adjusted inductive and capacitive sensors send electromagnetic and electric field signals to the surroundings, and receive reflected signals of the electromagnetic and electric field signals.

[0130] The first calculation module: calculates the distance value corresponding to the inductive sensor. The calculation formula is: , where is the distance value corresponding to the inductive sensor, is the propagation speed of electromagnetic waves, , is the round trip time of the electromagnetic signal;

[0131] The second calculation module calculates the distance value corresponding to the capacitive sensor. The calculation formula is: , where is the distance value corresponding to the capacitive sensor, is the round trip time of the electric field signal, is the propagation speed of the electric field signal, and the calculation formula is: , where is the propagation speed of electromagnetic waves, is the relative dielectric constant of the medium 1;

[0132] The third calculation module: multiplies the distance value corresponding to the inductive sensor by the corresponding distance weight value to obtain the first distance, multiplies the distance value corresponding to the capacitive sensor by the corresponding distance weight value to obtain the second distance, adds the first distance and the second distance, divides the result of the addition by the sum of the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor to obtain the final distance, and completes the distance measurement.

[0133] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A proximity switch distance measurement method based on a combination of inductance and capacitance, characterized in that: The following steps are involved: The control modules of the inductive sensor and the capacitive sensor are activated to detect the surrounding electromagnetic signals and electric field signals in real time, send electromagnetic signals and electric field signals to the surroundings, and determine the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals; Based on the material information of the moving object, identify and adjust the measurement distance weight values ​​corresponding to the inductive sensor and capacitive sensor when measuring the distance of the current moving object; Obtain the current ambient temperature and humidity of the moving object, and adjust the frequency of the inductive sensor and the capacitive sensor according to the current ambient temperature and humidity of the moving object; The distance measurement is completed according to the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor after the frequency adjustment; The steps for determining the material information of a moving object based on the reflected signals of the electromagnetic signal and the electric field signal are as follows: Extracting a reflected signal of the electromagnetic signal from the inductive sensor as a first signal, and extracting a reflected signal of the electric field signal from the capacitive sensor as a second signal; Preprocessing the first signal and the second signal, performing calculations based on the preprocessed first signal and the second signal, and obtaining the time from when the first signal and the second signal are transmitted to when they return to the corresponding inductive sensor and capacitive sensor, which are recorded as the first delay time and the second delay time; Calculating the amplitude integrals of the first signal and the second signal, and recording the integral results as the first signal strength value and the second signal strength value, respectively; Comparing the first signal strength value with the second signal strength value, and comparing the first delay time with the second delay time, if the first signal strength value is greater than the second signal strength value and the first delay time is less than the second delay time, then the corresponding material information of the moving object is likely to be metal; If the first signal strength value is less than the second signal strength value and the first delay time is greater than the second delay time, the probability that the material information of the corresponding moving object is non-metal is relatively high; If the first signal strength value is equal to the second signal strength value and the first delay time is equal to the second delay time, the probability that the material information of the corresponding moving object is non-metal and metal is equal.

2. The proximity switch distance measurement method based on the combination of inductance and capacitance according to claim 1 is characterized in that: Based on the material information of the moving object, the steps for identifying and adjusting the distance weight values ​​of the inductive sensor and the capacitive sensor corresponding to the current moving object for distance measurement are as follows: When the probability of the moving object's material information being non-metal and metal is equal, the corresponding distance weight values ​​of the inductive sensor and the capacitive sensor are both recorded as 0.5; When the probability that the material information of the moving object is metal is high or the probability that the material information of the moving object is metal is high, calculating the sum of the first signal strength value and the second signal strength value as the overall signal strength value; Dividing the first signal strength value and the second signal strength value by the overall signal strength value respectively to obtain corresponding signal strength weight values; Calculate the sum of the first delay time and the second delay time as the overall delay time; Divide the first delay time and the second delay time by the overall delay time respectively to obtain corresponding delay time weight values; The average of the corresponding signal strength weight value and the corresponding delay time weight value is used as the measurement distance weight value corresponding to the inductive sensor and the capacitive sensor.

3. The proximity switch distance measurement method based on the combination of inductance and capacitance according to claim 1 is characterized in that: The steps for obtaining the current ambient temperature and humidity of the moving object and adjusting the frequencies of the inductive sensor and the capacitive sensor according to the current ambient temperature and humidity of the moving object are as follows: The time when the electromagnetic signal and the electric field signal are sent is taken as the starting time, and the time from the starting time to the present is recorded as the time interval; the temperature and humidity of the environment in which the moving object is located during the time interval are obtained, and the average temperature and average humidity are calculated; Compare the average temperature and average humidity with the preset standard temperature and preset standard humidity respectively. If the average temperature is greater than the preset standard temperature, reduce the frequency of the inductive sensor and the capacitive sensor; If the average humidity is greater than the preset standard humidity, the frequency of the capacitive sensor is reduced.

4. The proximity switch distance measurement method based on the combination of inductance and capacitance according to claim 1, characterized in that: The steps for completing distance measurement according to the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor after frequency adjustment are as follows: The frequency-adjusted inductive sensors and capacitive sensors send electromagnetic signals and electric field signals to the surroundings, and receive reflected signals of the electromagnetic signals and electric field signals; Calculate the distance value corresponding to the inductive sensor. The calculation formula is: , where is the distance value corresponding to the inductive sensor, is the propagation speed of electromagnetic waves, , is the round trip time of the electromagnetic signal; Calculate the distance value corresponding to the capacitive sensor. The calculation formula is: , where is the distance value corresponding to the capacitive sensor, is the round trip time of the electric field signal, is the propagation speed of the electric field signal, and the calculation formula is: , where is the propagation speed of electromagnetic waves, is the relative dielectric constant of the medium 1; Multiply the distance value corresponding to the inductive sensor by the corresponding distance weight value to obtain the first distance, multiply the distance value corresponding to the capacitive sensor by the corresponding distance weight value to obtain the second distance, add the first distance and the second distance, divide the result of the addition by the sum of the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor to obtain the final distance, and complete the distance measurement.

5. The proximity switch distance measurement system based on the combination of inductance and capacitance is characterized by: The system comprises: Material information determination module: The control modules of the inductive sensor and the capacitive sensor are activated to detect the surrounding electromagnetic signals and electric field signals in real time, send electromagnetic signals and electric field signals to the surroundings, and determine the material information of the moving object based on the reflected signals of the electromagnetic signals and electric field signals; Distance weight module: Based on the material information of the moving object, it identifies and adjusts the distance weight values ​​corresponding to the inductive sensor and the capacitive sensor when measuring the distance of the current moving object; Adjustment module: obtains the ambient temperature and humidity of the current moving object, and adjusts the frequency of the inductive sensor and the capacitive sensor according to the ambient temperature and humidity of the current moving object; Distance measurement module: completes distance measurement based on the inductive sensor and capacitive sensor after frequency adjustment and the corresponding measured distance weight values ​​of the inductive sensor and capacitive sensor; The material information determination module includes: Signal extraction module: extracts the reflected signal of the electromagnetic signal from the inductive sensor as the first signal, and extracts the reflected signal of the electric field signal from the capacitive sensor as the second signal; Marking module: preprocesses the first signal and the second signal, performs calculations based on the preprocessed first signal and the second signal, and obtains the time from the first signal and the second signal being transmitted to the time when they return to the corresponding inductive sensor and capacitive sensor, which are recorded as the first delay time and the second delay time; Signal strength module: calculates the amplitude integral of the first signal and the second signal, and records the integral results as the first signal strength value and the second signal strength value respectively; A first comparison module compares the first signal strength value with the second signal strength value, and compares the first delay time with the second delay time. If the first signal strength value is greater than the second signal strength value and the first delay time is less than the second delay time, the corresponding moving object is likely to be metal. Second comparison module: if the first signal strength value is less than the second signal strength value and the first delay time is greater than the second delay time, then the probability that the material information of the corresponding moving object is non-metal is relatively high; Third comparison module: If the first signal strength value is equal to the second signal strength value and the first delay time is equal to the second delay time, the probability that the material information of the corresponding moving object is non-metal and metal is equal.

6. The proximity switch distance measurement system based on the combination of inductance and capacitance according to claim 5, characterized in that: The distance weight module includes: First distance weight value: When the probability of the moving object's material information being non-metal and metal is equal, the measurement distance weight values ​​corresponding to the inductive sensor and the capacitive sensor are both recorded as 0.5; Overall signal strength module: when the probability that the material information of the moving object is metal is high or the probability that the material information of the moving object is metal is high, the sum of the first signal strength value and the second signal strength value is calculated as the overall signal strength value; Signal strength weight module: divides the first signal strength value and the second signal strength value by the overall signal strength value to obtain corresponding signal strength weight values; Delay time weight module: calculates the sum of the first delay time and the second delay time as the overall delay time; divides the first delay time and the second delay time by the overall delay time respectively to obtain the corresponding delay time weight value; The second distance weight module uses the average of the corresponding signal strength weight value and the corresponding delay time weight value as the measurement distance weight value corresponding to the inductive sensor and the capacitive sensor.

7. The proximity switch distance measurement system based on the combination of inductance and capacitance according to claim 5, characterized in that: The adjustment module includes: Temperature and humidity calculation module: The time when the electromagnetic signal and electric field signal are sent is taken as the starting time, and the time from the starting time to the current time is recorded as the time interval; the temperature and humidity of the environment in which the moving object is located within the time interval are obtained, and the average temperature and average humidity are calculated; The first adjustment module compares the average temperature and average humidity with the preset standard temperature and preset standard humidity respectively. If the average temperature is greater than the preset standard temperature, the frequency of the inductive sensor and the capacitive sensor is reduced; The second adjustment module: if the average humidity is greater than the preset standard humidity, the frequency of the capacitive sensor is reduced.

8. The proximity switch distance measurement system based on the combination of inductance and capacitance according to claim 5, characterized in that: The distance measurement module includes: Retransmitter module: The frequency-adjusted inductive and capacitive sensors send electromagnetic and electric field signals to the surroundings, and receive reflected signals of the electromagnetic and electric field signals. The first calculation module: calculates the distance value corresponding to the inductive sensor. The calculation formula is: , where is the distance value corresponding to the inductive sensor, is the propagation speed of electromagnetic waves, , is the round trip time of the electromagnetic signal; The second calculation module calculates the distance value corresponding to the capacitance sensor, and the calculation formula is: , where is the distance value corresponding to the capacitive sensor, is the round trip time of the electric field signal, is the propagation speed of the electric field signal, and the calculation formula is: , where is the propagation speed of electromagnetic waves, is the relative dielectric constant of the medium 1; The third calculation module: multiplies the distance value corresponding to the inductive sensor by the corresponding distance weight value to obtain the first distance, multiplies the distance value corresponding to the capacitive sensor by the corresponding distance weight value to obtain the second distance, adds the first distance and the second distance, divides the result of the addition by the sum of the measured distance weight values ​​corresponding to the inductive sensor and the capacitive sensor to obtain the final distance, and completes the distance measurement.

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