Cylinder position detection method and cylinder position detection device

Abstract

The invention discloses a cylinder position detection method and a cylinder position detection device.A magnet ring is arranged on a cylinder, two independent sensors which are arranged at a preset interval are arranged in the motion range of the cylinder, and the cylinder position detection method comprises the steps that a voltage-magnetic field intensity conversion model is built; the cylinder is driven to move; receiving and recording voltages output by the two sensors in real time in the movement process of the air cylinder, and converting the voltages into a plurality of corresponding magnetic field intensity data through a voltage-magnetic field intensity conversion model; establishing two magnetic field intensity tables corresponding to the two independent sensors; calculating a coefficient of the magnetic field intensity and the cylinder movement distance based on a coefficient algorithm of the magnetic field intensity and the cylinder movement distance; and selecting two pieces of magnetic field intensity data which are not zero from the two magnetic field intensity tables, and obtaining the movement distance of the cylinder in the two pieces of magnetic field intensity data according to the product of the difference value of the two pieces of magnetic field intensity data and the coefficient. Compared with the prior art, the accurate position of the air cylinder can be calculated.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of cylinder position detection method and cylinder position detection device, belong to cylinder detection technical field. BACKGROUND

[0002] In the field of industrial automation, pneumatic actuator, especially cylinder, is widely used in various mechanical equipment and production lines as a key driving component to realize linear reciprocating motion or clamping positioning due to its simple structure, low cost, easy maintenance and strong adaptability. To ensure reliable operation, accurate control and real-time monitoring of the device state, accurate detection of the cylinder piston rod position is crucial.

[0003] Currently, the most commonly used cylinder position detection device is a magnetic cylinder detection switch based on magnetic induction principle (commonly known as a magnetic switch). Its working principle is to embed a permanent magnet on the cylinder piston and install a magnetic switch sensor at a specific position on the outer wall of the cylinder. When the piston moves to the sensor installation position, the reed or Hall element inside the sensor acts under the action of the magnetic field, generating a switch signal (usually "on" or "off").

[0004] However, this traditional magnetic cylinder detection switch has significant limitations:

[0005] 1. Single-point position detection: Each magnetic switch sensor can usually only accurately sense and report whether the cylinder piston has reached the single, fixed position where it is installed. It can only provide binary state information that the piston has "reached" or "not reached" that specific point.

[0006] 2. Dual sensor requirement: Since the working cycle of the cylinder usually includes two key end point positions of "fully extended" and "fully retracted", in order to fully determine the entire stroke state of the cylinder (i.e., to distinguish whether it is extended to the position or retracted to the position), at least two magnetic switch sensors must be installed: one at the position corresponding to the fully extended piston on the cylinder body, and the other at the position corresponding to the fully retracted piston. Only through the combination of signals from the two sensors (e.g., A on B off indicates extended to the position, A off B on indicates retracted to the position, and A off B off indicates in the middle position) can the end point state of the cylinder be reliably determined.

[0007] 3. Lack of position information: This on-off detection method cannot provide any specific position information of the piston at any intermediate point in the stroke. Once the piston leaves the positions of the two installed points, the system can only know that the piston is "in the stroke" (i.e., not at the end point position), but it cannot perform any quantitative or continuous monitoring of the precise position, movement speed or direction (in the intermediate stroke segment). The sensor output is only a discrete switch signal, lacking analog or digital position feedback.

[0008] Therefore, it is necessary to improve the existing cylinder position detection method to solve the above problems. SUMMARY

[0009] To solve the above technical problems, the present application provides a cylinder position detection method, which can measure a movable magnetic ring through two sensors with a fixed distance. The relative position of the magnetic ring is calculated through the magnetic field strength sensed by the sensors, and the accurate position of the cylinder is further calculated.

[0010] The technical solution of the present application is:

[0011] A cylinder position detection method, the cylinder is provided with a magnetic ring, and two independent sensors are provided in the movement range of the cylinder and are spaced apart at a preset interval. The sensors are configured to be able to sense the magnetic field strength of the magnetic ring and output corresponding voltages. The cylinder position detection method comprises:

[0012] Constructing a voltage-magnetic field strength conversion model;

[0013] Driving the cylinder to move;

[0014] Receiving and recording the voltages output by the two sensors in real time during the movement of the cylinder, and inputting the real-time recorded voltage data into the voltage-magnetic field strength conversion model to convert into corresponding magnetic field strength data;

[0015] Establishing two magnetic field strength tables corresponding to the two independent sensors according to the converted magnetic field strength data;

[0016] Taking the preset distance between the two sensors as the basis of the movement distance of the cylinder, calculating the coefficient of the magnetic field strength and the movement distance of the cylinder based on the coefficient algorithm of the magnetic field strength and the movement distance of the cylinder;

[0017] Selecting two non-zero magnetic field strength data in the two magnetic field strength tables, and obtaining the distance moved by the cylinder within the two magnetic field strength data according to the product of the difference between the two magnetic field strength data and the coefficient.

[0018] As a further improvement of the present application, the voltage output by the sensor, the magnetic field strength of the magnetic ring, and the distance between the cylinder and the corresponding sensor are directly proportional.

[0019] As a further improvement of the present application, the coefficient algorithm of the magnetic field strength and the movement distance of the cylinder comprises:

[0020] Selecting the maximum magnetic field strength with the same absolute value in the two magnetic field strength tables as the first magnetic field strength, and selecting the magnetic field strength with the same absolute value at the same time in the two magnetic field strength tables as the second magnetic field strength.

[0021] The difference between the first magnetic field intensity and the second magnetic field intensity is recorded as a third magnetic field intensity;

[0022] The quotient of half of the preset interval and the third magnetic field intensity is recorded as a coefficient of the magnetic field intensity and the cylinder movement distance.

[0023] As a further improvement of the present application, the sensors have induction areas for inducing the magnetic field intensity of the magnetic ring, the induction areas spread to both sides of the sensors, and any sensor is located outside the induction area of the other sensor.

[0024] As a further improvement of the present application, the induction areas of the two sensors intersect with each other and form an intersection area, and the magnetic ring is located in the intersection area when both sensors induce the second magnetic field intensity.

[0025] As a further improvement of the present application, the magnetic ring is located on the center line of the intersection area, and the center line of the intersection area overlaps the center line of the preset interval.

[0026] As a further improvement of the present application, the voltage output by the sensor has a positive voltage and a negative voltage, and the moving direction of the magnetic ring is determined according to the positive and negative value of the voltage output by the sensor in an induction period.

[0027] As a further improvement of the present application, the magnetic ring has N and S poles, the voltage output by the sensor is a positive voltage when the sensor faces the N pole of the magnetic ring, and the voltage output by the sensor is a negative voltage when the sensor faces the S pole of the magnetic ring; in an induction period, when the voltage output by the sensor gradually changes from a positive voltage to a negative voltage, the magnetic ring moves in a direction from the N pole to the S pole, and when the voltage output by the sensor gradually changes from a positive voltage to a negative voltage, the magnetic ring moves in a direction from the S pole to the N pole.

[0028] As a further improvement of the present application, the cylinder has a retracted position and an extended position, and both sensors are located between the retracted position and the extended position, and the cylinder position detection method further comprises: selecting the magnetic field intensity when the cylinder is located at the retracted position and the extended position respectively, and determining the orientation of the N and S poles of the magnetic ring according to the positive and negative values of the two magnetic field intensities.

[0029] The present application also discloses a cylinder position detection device, which can measure a movable magnetic ring through two sensors with a fixed distance, calculate the relative position of the magnetic ring through the magnetic field intensity induced by the sensors, and further calculate the accurate position of the cylinder.

[0030] The technical scheme of the present application is:

[0031] A cylinder position detection device applying the cylinder position detection method, the cylinder position detection device further comprises a display device and a control module, the control module is connected with the display device and the sensor respectively, and is configured to receive and process the voltage information output by the sensor, and control the display device to operate.

[0032] The beneficial technical effect of the present application is: the cylinder position detection method of the present application sets two independent sensors at a preset interval in the movement range of the cylinder, receives and records the real-time voltage output by the two sensors during the movement of the cylinder when driving the cylinder to move, inputs the real-time recorded voltage data into the voltage-magnetic field strength conversion model, converts it into a plurality of corresponding magnetic field strength data, and takes the preset distance between the two sensors as the basis of the movement distance of the cylinder, calculates the coefficient of the magnetic field strength and the movement distance of the cylinder based on the coefficient algorithm of the magnetic field strength and the movement distance of the cylinder; after calculating the coefficient, the product of the difference of the two selected magnetic field strengths and the coefficient is obtained. The distance of the cylinder moving in the two magnetic field strength data. In this way, it is realized to measure a movable magnetic ring through two sensors with fixed distance. And the relative position of the magnetic ring is calculated through the magnetic field strength sensed by the sensor, and then the accurate position of the cylinder is calculated. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a flow chart of the cylinder position detection method according to the preferred embodiment of the present application.

[0034] Figure 2 is a structure schematic diagram of the cylinder position detection device applying the cylinder position detection method shown in Figure 1

[0035] Figure 3 is a structure schematic diagram of the sensor, the control module and the display device in Figure 2

[0036] Figure 4 is a structure schematic diagram of the movement position of the cylinder and the two sensors in Figure 2

[0037] Figure 5 is a change diagram of the magnetic field strength sensed by the two sensors in Figure 2

[0038] Figure 6 is a corresponding diagram of the magnetic field strength and the output voltage sensed by a single sensor in Figure 5 DETAILED DESCRIPTION

[0039] ​​​​​In order to enable a clearer understanding of the technical means of the present application, and to implement the content of the specification, the specific embodiments of the present application are further described in detail below in combination with the drawings and examples, the following examples are used to illustrate the present application, but not to limit the scope of the present application.

[0040] Referring to Figures 1 to 5 As shown in the drawings, the present application discloses a kind of cylinder position detection device, and the cylinder position detection device includes cylinder.The cylinder is equipped with magnetic ring 2, and has extension state and contraction state, in the movement range of the cylinder, two independent and with preset interval interval sensor 1 are provided, the sensor 1 is configured to be able to sense the magnetic field intensity of the magnetic ring 2, and output corresponding voltage.Usually, the sensor 1 also outputs fixed voltage or does not output voltage when not sensing the magnetic field intensity of magnetic ring 2;After sensing the magnetic field intensity of magnetic ring 2, the voltage output by the sensor 1 changes under the influence of the magnetic field intensity of the magnetic ring 2.The sensor 1 is preferably linear magnetic sensitive component, and the magnetic ring 2 can also be other permanent magnet.The sensor 1 is arranged on PCB board 10, and the cylinder is located at the outer side of the PCB board 10 and moves parallelly along the extension direction of the PCB board 10.

[0041] Usually, the voltage output by the sensor 1 is proportional to the magnetic field intensity of the magnetic ring 2. That is, the stronger the magnetic field intensity of the magnetic ring 2, the higher the voltage output by the sensor 1.

[0042] In the embodiment, the cylinder has contraction position corresponding to contraction state and extension position corresponding to extension state, and the two sensors 1 are located between the contraction position and the extension position. That is, the movement process of the cylinder is a process of moving close to the sensor 1 and then moving away.

[0043] Usually, the closer the distance between the cylinder and the sensor 1, the greater the magnetic field intensity of the magnetic ring 2 sensed by the sensor 1, and at this time, the greater the voltage output by the sensor 1. Therefore, the voltage output by the sensor 1, the magnetic field intensity of the magnetic ring 2 and the distance between the cylinder and the corresponding sensor are proportional. Based on this, when the cylinder moves to the relative position of the sensor 1, the magnetic field intensity of the magnetic ring 2 sensed by the sensor 1 is the largest. That is, for a single sensor 1, the sensed magnetic field intensity is a process of first increasing and then decreasing.

[0044] In the embodiment, the sensor 1 has a sensing area for sensing the magnetic field intensity of the magnetic ring 2, the sensing area spreads to both sides along the sensor, and any sensor 1 is located outside the sensing area of the other sensor. That is, when the cylinder extends or retracts to the position of the other sensor 1, only one sensor 1 can sense the magnetic field intensity of the magnetic ring 2.

[0045] That is, the magnetic field intensity sensed by the sensor 1 spreads to both sides with the position of the sensor 1 as the center point. As shown in the drawings, it is similar to a U-shaped parabola.

[0046] The voltage output by the sensor 1 has positive voltage and negative voltage. In the embodiment, the magnetic ring 2 has N and S poles, when the sensor 1 is directed to the N pole of the magnetic ring 2, the voltage output by the sensor is positive voltage, and when the sensor is directed to the S pole of the magnetic ring 2, the voltage output by the sensor is negative voltage. The sensor 1 is preferably a differential sensor, which can accurately display the positive and negative values of the output voltage.

[0047] The cylinder position detection device further comprises a display device 4, a control module 3 and a switch 5, the control module 3 is connected with the display device 4 and the sensor 1 respectively, and is configured to receive and process the voltage information output by the sensor 1, and control the display device 4 to operate. The display device 4 is preferably an LED lamp, and whether the cylinder is in the sensing range of the sensor 1 is judged by the opening or closing of the LED lamp. That is, when the LED lamp emits light, it proves that the cylinder is in the sensing range of the sensor 1. The switch 5 is used to start the movement of the cylinder.

[0048] Please combine Figure 6 The application further discloses a cylinder position detection method, and the cylinder position detection method comprises the following steps:

[0049] constructing a voltage-magnetic field intensity conversion model;

[0050] driving the cylinder to move;

[0051] receiving and recording the voltage output by the two sensors 1 in real time during the movement of the cylinder, and inputting the real-time recorded voltage data into the voltage-magnetic field intensity conversion model to convert into corresponding magnetic field intensity data;

[0052] establishing two magnetic field intensity tables corresponding to the two independent sensors 1 according to the converted magnetic field intensity data;

[0053] The preset distance between the two sensors 1 is taken as the basis of the cylinder movement distance, and the coefficient of the magnetic field strength and the cylinder movement distance is calculated based on the coefficient algorithm of the magnetic field strength and the cylinder movement distance;

[0054] In the two magnetic field strength tables, two non-zero magnetic field strength data are selected, and the distance of the cylinder movement within the two magnetic field strength data is obtained according to the product of the difference between the two magnetic field strength data and the coefficient. Because the two sensors 1 are outside the sensing area of each other, the zero value may occur multiple times. In order to ensure accuracy, the non-zero magnetic field strength data is preferentially selected.

[0055] The control module can be provided with the voltage-magnetic field strength conversion model, and the voltage-magnetic field strength conversion model has a mapping table of voltage values and magnetic field strengths. Each voltage value has a corresponding magnetic field strength value. Through the voltage-magnetic field strength conversion model, the control module can receive the voltage value output by the sensor 1 and convert it into the corresponding magnetic field strength. The mapping table of voltage values and magnetic field strengths can be fitted after testing multiple voltage values and the corresponding magnetic field strengths of the voltage values, or the complete table can be listed by the exhaustion method.

[0056] In the two magnetic field strength tables, the maximum magnetic field strength with the same absolute value is selected as the first magnetic field strength, and the magnetic field strength with the same absolute value at the same time is selected as the second magnetic field strength;

[0057] The difference between the first magnetic field strength and the second magnetic field strength is recorded as the third magnetic field strength;

[0058] The quotient of half of the preset interval and the third magnetic field strength is recorded as the coefficient of the magnetic field strength and the cylinder movement distance.

[0059] Because the voltage output by the sensor 1, the magnetic field strength of the magnetic ring 2, and the distance between the cylinder and the corresponding sensor 1 are proportional. Therefore, when the sensor 1 senses the first magnetic field strength, it is the relative position of the sensor 1 and the cylinder. The sensing areas of the two sensors 1 intersect each other and form an intersection area. When both sensors 1 sense the second magnetic field strength, the magnetic ring 2 is located in the intersection area. The magnetic ring 2 is located on the center line of the intersection area, and the center line of the intersection area overlaps the center line of the preset interval. Therefore, when the movement process of the cylinder is that the first magnetic field strength sensed by the sensor 1 changes to the second magnetic field strength, or the second magnetic field strength changes to the first magnetic field strength, the movement distance of the cylinder is half of the preset distance between the two sensors 1.

[0060] Therefore, the coefficient of the magnetic field intensity and the cylinder movement distance can be obtained by the calculation formula:

[0061]

[0062] Wherein, Y is the coefficient, X is the preset distance between the two sensors, Q1 is the first magnetic field intensity, and QS is the second magnetic field intensity. The coefficient is the distance of the cylinder movement when the single magnetic field intensity changes.

[0063] After obtaining the coefficient, the actual movement distance of the cylinder can be calculated by the difference between the two magnetic field intensities.

[0064] Because the magnetic ring 2 has N and S poles, the direction of the N and S poles of the magnetic ring 2 is determined according to the positive and negative values of the two magnetic field intensities. Preferably, the magnetic field intensities when the cylinder is at the retracted position and the extended position are selected respectively, and the direction of the N and S poles of the magnetic ring 2 is determined according to the positive and negative values of the two magnetic field intensities.

[0065] In an induction cycle, when the voltage output by the sensor 1 gradually changes from positive voltage to negative voltage, the magnetic ring 2 moves in the direction of the N pole towards the S pole, and when the voltage output by the sensor gradually changes from negative voltage to positive voltage, the magnetic ring 2 moves in the direction of the S pole towards the N pole. In this way, the movement direction of the cylinder can be determined.

[0066] Preferably, in use, the retracted position of the cylinder is defined as the origin, the extended position of the cylinder is defined as the far point, the position of the sensor 1 close to the cylinder is defined as the first positioning point, the position of the sensor 1 away from the cylinder is defined as the second positioning point, the distance A between the origin and the first positioning point, the distance B between the far point and the second positioning point, and the preset distance X between the two sensors 1 are all fixed, then the distance X1 between the first positioning point and the position of the cylinder when the sensor 1 senses the second magnetic field intensity is also fixed, and X1 is half of X. On this basis, the position of the cylinder can be accurately calculated based on the origin, the far point, the first positioning point and the second positioning point, through the movement direction of the cylinder and the coefficient. Generally, the first positioning point is used as the reference for calculation when the cylinder is close to the retracted position, and the second positioning point is used as the reference for calculation when the cylinder is close to the extended position.

[0067] Specifically, in the two magnetic field intensity tables, two non-zero magnetic field intensity data are selected, and the distance of the cylinder movement within the two magnetic field intensity data can be obtained according to the product of the difference between the two magnetic field intensity data and the coefficient: first, the magnetic field intensity when the first positioning point or the second positioning point is determined, i.e. the first magnetic field intensity, and then the difference between the first magnetic field intensity and the magnetic field intensity corresponding to the current voltage value output by the sensor 1 is used to determine the position of the cylinder.

[0068] In summary, the cylinder position detection method and cylinder position detection device of the present application sets two independent sensors 1 at a preset interval in the movement range of the cylinder, receives and records the voltage output by the two sensors 1 in real time during the movement of the cylinder, inputs the real-time recorded voltage data into the voltage-magnetic field strength conversion model, converts it into corresponding magnetic field strength data, takes the preset distance between the two sensors 1 as the basis for the movement distance of the cylinder, calculates the coefficient of the magnetic field strength and the movement distance of the cylinder based on the coefficient algorithm of the magnetic field strength and the movement distance of the cylinder; after calculating the coefficient, the product of the difference between the two selected magnetic field strengths and the coefficient is obtained, which is the distance moved by the cylinder within the two magnetic field strength data. In this way, it is realized to measure a movable magnetic ring through two sensors 1 with a fixed distance. And the relative position of the magnetic ring is calculated through the magnetic field strength sensed by the sensor, and then the accurate position of the cylinder is calculated.

[0069] The above is only the preferred embodiment of the present application, and is not used to limit the present application. It should be pointed out that for ordinary skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should be considered as the protection scope of the present application.

Claims

1. A method for detecting the position of a cylinder, wherein a magnetic ring is provided on the cylinder, and two independent sensors are provided within the range of motion of the cylinder and are spaced apart at a predetermined distance. The sensors are configured to sense the magnetic field strength of the magnetic ring and output a corresponding voltage, characterized in that: The cylinder position detection method comprises: Construct a voltage-magnetic field intensity conversion model; driving the cylinder to move; Receive and record the voltages output by the two sensors in real time during the movement of the cylinder, and input the real-time recorded voltage data into the voltage-magnetic field strength conversion model to convert them into corresponding magnetic field strength data; Two magnetic field intensity tables corresponding to two independent sensors are established according to a plurality of converted magnetic field intensity data; The preset distance between the two sensors is used as the basis for the cylinder movement distance, and the coefficient of the magnetic field strength and the cylinder movement distance is calculated based on the coefficient algorithm of the magnetic field strength and the cylinder movement distance; Two non-zero magnetic field strength data are selected from the two magnetic field strength tables, and the distance the cylinder moves within the two magnetic field strength data is obtained based on the product of the difference between the two magnetic field strength data and the coefficient.

2. The cylinder position detection method according to claim 1, characterized in that: The voltage output by the sensor is proportional to the magnetic field strength of the magnetic ring and the distance between the cylinder and the corresponding sensor.

3. The cylinder position detection method according to claim 2, characterized in that: The coefficient algorithm of the magnetic field strength and the cylinder movement distance includes: Select the maximum magnetic field intensity with the same absolute value in the two magnetic field intensity tables and record it as the first magnetic field intensity; select the magnetic field intensity with the same absolute value in the two magnetic field intensity tables at the same time and record it as the second magnetic field intensity; Recording the difference between the first magnetic field strength and the second magnetic field strength as a third magnetic field strength; The quotient of half the preset distance and the third magnetic field strength is recorded as a coefficient of the magnetic field strength and the cylinder movement distance.

4. The cylinder position detection method according to claim 3, characterized in that: The sensor has a sensing area for sensing the magnetic field strength of the magnetic ring. The sensing area spreads toward both sides with the sensor as the center. Any sensor is located outside the sensing area of ​​another sensor.

5. The cylinder position detection method according to claim 4, characterized in that: The sensing areas of the two sensors intersect with each other to form a cross area. When both sensors sense the second magnetic field strength, the magnetic ring is located in the cross area.

6. The cylinder position detection method according to claim 5, characterized in that: The magnetic ring is located on a center line of the intersection area, and the center line of the intersection area overlaps with a center line of the preset distance.

7. The cylinder position detection method according to claim 1, characterized in that: The voltage output by the sensor has positive voltage and negative voltage. The moving direction of the magnetic ring is determined according to the change in the positive and negative values ​​of the voltage output by the sensor within one induction cycle.

8. The cylinder position detection method according to claim 7, characterized in that: The magnetic ring has an N pole and an S pole. When the sensor is facing the N pole of the magnetic ring, the voltage output by the sensor is a positive voltage. When the sensor is facing the S pole of the magnetic ring, the voltage output by the sensor is a negative voltage. Within an induction cycle, when the voltage output by the sensor gradually changes from a positive voltage to a negative voltage, the magnetic ring moves in the direction from the N pole to the S pole. When the voltage output by the sensor gradually changes from a positive voltage to a positive voltage, the magnetic ring moves in the direction from the S pole to the N pole.

9. The cylinder position detection method according to claim 8, characterized in that: The cylinder has a retracted position and an extended position, and the two sensors are located between the retracted position and the extended position. The cylinder position detection method also includes: selecting the magnetic field strength when the cylinder is in the retracted position and the extended position respectively, and judging the orientation of the N pole and S pole of the magnetic ring according to the positive and negative values ​​of the two magnetic field strengths.

10. A cylinder position detection device, characterized in that: The cylinder position detection method as described in any one of claims 1 to 9 is applied, and the cylinder position detection device also includes a display device and a control module, the control module is connected to the display device and the sensor respectively, and is configured to receive and process the voltage information output by the sensor, and control the operation of the display device.

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