Optical electromechanical material level meter and use method thereof

Abstract

The invention discloses an optomechanical material level meter and a use method thereof, comprising a powder tank, wherein a main control chip is arranged on the top of the powder tank; a wireless communication module is electrically connected to the main control chip; a winding drum is connected to a base on one side in an equipment box, and the winding drum is connected to an output end of a motor; the winding drum is connected to a mechanical detection mechanism through a steel cable; the mechanical detection mechanism comprises a fixed pulley block, one end of the steel cable bypasses the fixed pulley block and is connected to a solid ball, and the solid ball extends into the powder tank through an opening at the top of the powder tank; a knocking and sound pickup device is arranged on the top of the powder tank, and the knocking and sound pickup device cooperates with the steel cable; the invention detects the material level through the steel cable and the solid ball of the mechanical structure, performs auxiliary material level judgment through acoustics, performs auxiliary material level calculation through optical detection, realizes data comparison and correction through the linkage of multiple detection mechanisms, thereby obtaining material level data with high precision, and can still maintain high efficiency and high precision operation at a work site with large dust and noise influence.

Description

Technical Field

[0001] The invention belongs to the field of automatic instruments for level detection, and in particular relates to an optomechanical material level meter and a use method thereof. Background Art

[0002] At present, optical and acoustic detection devices are often used on the market to detect the material level in the tank. However, when detecting powder materials, due to the large amount of dust inside the tank, the diffuse reflection caused by the dust will cause the optical detection device such as laser ranging to fail or have large errors. Some material tanks are set in places with high noise, and the tanks are connected to the processing equipment, and the tank body vibrates. The existing acoustic detection devices often use the method of sticking on the tank body for detection, which is easily affected by noise and tank vibration, resulting in large errors in the detection results. In addition, the surface flatness of the material inside the tank is poor, and it is difficult to detect it directly on the tank body. Acoustic detection on the surface of the tank can only distinguish the height of the material level line at the edge where the material contacts the inner wall of the tank, and it is difficult to effectively and accurately detect the high and low positions of the internal material plane, and the accuracy is poor; therefore, the existing technology is not suitable for high-precision detection in places with high dust and noise; mechanical measuring devices are often expensive and easily blocked by dust, causing mechanical parts to fail; many places use traditional manual measurement, which is not only inefficient, but also requires opening the tank for multi-point detection, and also causes dust to escape and pollute the working environment; therefore, it is necessary to design an optomechanical level meter and a method of use to solve the above problems. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an optomechanical material level meter and a method of use. The device and method have low cost, can be effectively loaded and used on the surfaces of various existing powder tanks, can be linked by various detection mechanisms to achieve data comparison and correction, thereby obtaining material level data with higher accuracy, and can maintain high efficiency and high precision at work sites with greater dust and noise impact.

[0004] To realize the above design, the technical solution adopted by the present invention is: an optomechanical level meter, including a powder tank, a device box is arranged on the top of the powder tank, and a main control chip is installed in the device box; a wireless communication module is connected to the top of the device box and is electrically connected to the main control chip; a winding drum is connected to the base on one side of the device box, and the winding drum is connected to the output end of the motor; the winding drum is connected to the mechanical detection mechanism through a steel cable.

[0005] Furthermore, the main control chip is preferably an industrial computer of model GX701-L or a Siemens S7-200 PLC controller.

[0006] Furthermore, the wireless communication module is preferably a Bluetooth transceiver module.

[0007] Preferably, a distance measuring device is connected to one side of the main control chip, and the distance measuring device faces the winding drum.

[0008] Furthermore, the distance measuring device is preferably a laser distance sensor, and the light spot of the distance measuring device is oriented toward the center of the winding groove of the winding drum, facing the highest protruding point on the surface of the steel cable.

[0009] Preferably, the mechanical detection mechanism comprises a fixed pulley block, one end of the steel cable passes around the fixed pulley block and is connected to a solid ball, and the solid ball extends into the powder tank through an opening at the top of the powder tank.

[0010] Furthermore, the equipment box and the mechanical detection mechanism are connected to the tank body by magnetic attraction.

[0011] Preferably, the mechanical detection mechanism comprises a knocking and sound-picking device connected to the top of the powder tank, and the knocking and sound-picking device cooperates with the steel cable.

[0012] Furthermore, the striking and sound-picking device comprises a steel bar driven by a motor, which rotates at a constant speed and periodically strikes the steel cable; the sound-picking device is preferably a SK-450X pickup.

[0013] Preferably, the mechanical detection mechanism includes a travel switch, which is connected to the inner wall of the opening of the powder tank through which the solid ball passes, and the travel switch and the knocking and sound pickup device are electrically connected to the main control chip.

[0014] Preferably, a brush is connected to the surface of the powder tank below the fixed pulley block, and the steel cable passes through the brush and extends into the powder tank.

[0015] Furthermore, the brush is used to remove dust adhering to the surface of the steel cable after the detection action is completed, so as to keep the device clean and avoid the dust from causing hysteresis of mechanical action during subsequent detection.

[0016] Preferably, the winding drum is a columnar structure, and an annular winding groove is provided on the surface of the winding drum, and the width of the winding groove is the same as the diameter of the steel cable.

[0017] Furthermore, the width of the winding groove is the same as the diameter of the steel cable, ensuring that the steel cable is in the same plane after being rolled up, and ensuring that the thickness of the steel cable accurately corresponds to the number of turns of the steel cable.

[0018] Preferably, the method for using the above-mentioned optomechanical level meter comprises the following steps:

[0019] S1, install the equipment on the top of the powder tank to be tested, set the encoder and Hall element current sensor at the motor; pull up the steel cable to make the solid ball touch the travel switch, record the encoder angle at this time as the initial value, and record the distance data of the distance measuring device at this time as the initial distance; then lower the steel cable, at this time the load provided by the solid ball is large, and the detected motor current is large;

[0020] S2, continue to lower the steel cable so that the solid ball touches the highest point on the top of the material in the powder tank and obtains support. The motor loses the load of the solid ball. At this time, the motor current suddenly decreases. The Hall element current sensor sends the current magnitude signal to the main control chip. When the main control chip detects that the current suddenly decreases sharply, it sends a trigger signal that the solid ball reaches the top of the material in the powder tank, and records the number of encoder circles and angles at this time as the high material level value, and records the distance data of the distance measuring device at this time as the high material level distance;

[0021] S3, continue to lower the steel cable, the solid ball automatically slides down along the slope at the top of the powder to the lowest point at the top of the material. During this process, the current signal may continue to oscillate. Continue to lower the steel cable until the current signal is stable, which indicates that the solid ball has touched the lowest point on the surface of the material. After staying for a period of time t, start the motor to reverse and raise the steel cable. At first, the current is stable at a small value. When the steel cable is completely straightened and the solid ball is separated from the lowest point on the top of the material, the motor obtains part or all of the load of the solid ball, and the current suddenly increases. The Hall element current sensor sends the current size signal to the main control chip. The main control chip sends a signal that the steel cable has reached the lowest point on the top of the material, and records the number of turns and angle of the encoder as the low material level value, and records the distance data of the distance measuring device as the low material level distance.

[0022] S4, during the process of S1 to S3, the knocking and sound pickup device continuously knocks the steel cable with a period T, and obtains the sound frequency data through the main control chip; when the steel cable carries a solid ball load, the steel cable is taut, and the response frequency after knocking is high; when the steel cable is lowered so that the solid ball reaches the top of the material inside the powder tank for support, the steel cable is relaxed, and the response frequency after knocking is low. At this time, the main control chip determines that the sound frequency suddenly decreases as a signal that the lowered steel cable has reached the top of the material; when the steel cable is raised, when the solid ball leaves the lowest point on the top of the material, the steel cable is taut again, and the frequency suddenly increases after knocking. The main control chip determines that the sound frequency suddenly increases as a signal that the lowered steel cable has reached the lowest point on the top of the material;

[0023] S5, when the solid ball reaches the highest and lowest points on the material surface, the main control chip needs to obtain the current signal and the sound frequency signal at the same time. When the two judgment signals are obtained at the same time, the detection action is judged to be qualified and the calculation program is run; otherwise, the detection action is judged to be invalid and an error is reported, and the above S~S are repeated for re-detection;

[0024] S6, the calculation procedure is as follows:

[0025] a. Count the number of turns and angles of the winding drum through the feedback of the encoder; measure the distance change to the steel rope on the winding drum through the distance measuring device, thereby obtaining the change in the thickness of the steel rope on the winding drum, and calculate the number of turns reduced by the steel rope through the ratio of the distance to the diameter of the steel rope; determine whether the number of turns of the encoder is consistent with the number of turns measured and calculated by the distance measuring device; if not, reset the steel rope position to zero and re-measure; if consistent, execute the following step b;

[0026] b. Assume the number of turns of the steel rope on the winding drum is n, the radius of the winding drum is r, the diameter of the steel rope is d, the rotation angle of the motor is α, and the total height inside the powder tank is H; then the length of the i-th turn of the full circle of steel rope = 2π*r+i*d;

[0027] The nth circle of steel rope does not make a complete circle, and its length = 2π*(α / 360-(n-1))*(r+n*d);

[0028] c.

[0029] d. Take the average of the length of the steel cable when it reaches the highest point of the silo material level and the length of the steel cable when it reaches the lowest point of the silo material level to obtain the material height, thereby avoiding errors caused by uneven material stacking.

[0030] Furthermore, the material level data is transmitted to the user end via a wireless communication module.

[0031] The beneficial effects of the present invention are as follows:

[0032] The present invention determines the material level height by setting a steel cable and a solid ball of a mechanical structure, and utilizes the rolling characteristics of the solid ball to more accurately know the positions of the high and low points on the material level surface, thereby taking the average value to calculate the material level data with higher accuracy; the present invention also provides a sound collection device to assist in determining the high and low positions of the material level, and to match and compare with the mechanical structure, thereby avoiding the problem of failure or misalignment caused by the use of a separate detection mechanism; the device also provides a distance sensor to cooperate with a specially designed winding drum, which can verify the data collection part of the mechanical structure, and also avoid the problem of misalignment in the data collection part. The complementary nature of multiple detection methods greatly ensures the reliability and accuracy of the detection data; the device body has a simple and stable structure, low cost, and is easy to be deployed and used on various existing tank bodies, and can also effectively avoid the influence of dust and noise in the tank body, and is suitable for large-scale use in existing factories. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the device of the present invention;

[0034] Figure 2 It is a structural schematic diagram of the mechanical detection mechanism in the present invention;

[0035] In the figure: powder tank 1, main control chip 2, wireless communication module 3, motor 4, winding drum 5, distance measuring device 6, knocking and sound picking device 7, travel switch 8, steel cable 9, brush 10, solid ball 11, fixed pulley set 12. DETAILED DESCRIPTION

[0036] Embodiment 1:

[0037] like Figure 1-2 In the invention, an optomechanical material level meter includes a powder tank 1, a device box is arranged on the top of the powder tank 1, and a main control chip 2 is installed in the device box; a wireless communication module 3 is connected to the top of the device box and is electrically connected to the main control chip 2; a winding drum 5 is connected to the base on one side of the device box, and the winding drum 5 is connected to the output end of the motor 4; the winding drum 5 is connected to the mechanical detection mechanism through a steel cable 9.

[0038] Furthermore, the main control chip 2 is preferably an industrial computer of model GX701-L or a Siemens S7-200 PLC controller.

[0039] Furthermore, the wireless communication module 3 is preferably a Bluetooth transceiver module.

[0040] Preferably, a distance measuring device 6 is connected to one side of the main control chip 2 , and the distance measuring device 6 faces the winding drum 5 .

[0041] Furthermore, the distance measuring device 6 is preferably a laser distance sensor, and the light spot of the distance measuring device 6 is oriented toward the center of the winding groove of the winding drum 5, facing the highest protruding point on the surface of the steel cable 9.

[0042] Preferably, the mechanical detection mechanism includes a fixed pulley block 12 , one end of the steel cable 9 passes around the fixed pulley block 12 and is connected to the solid ball 11 , and the solid ball 11 extends into the powder tank 1 through an opening at the top of the powder tank 1 .

[0043] Furthermore, the equipment box and the mechanical detection mechanism are connected to the tank body by magnetic attraction.

[0044] Preferably, the mechanical detection mechanism comprises a knocking and sound pickup device 7 connected to the top of the powder tank 1 , and the knocking and sound pickup device 7 cooperates with the steel cable 9 .

[0045] Furthermore, the striking and sound-picking device 7 comprises a steel bar driven by a motor, which rotates at a constant speed to periodically strike the steel cable 9; the sound-picking device is preferably a SK-450X pickup.

[0046] Preferably, the mechanical detection mechanism includes a travel switch 8 , which is connected to the inner wall of the opening of the powder tank 1 through which the solid ball 11 passes, and the travel switch 8 and the knocking and sound pickup device 7 are electrically connected to the main control chip 2 .

[0047] Preferably, a brush 10 is connected to the surface of the powder tank 1 below the fixed pulley block 12 , and the steel cable 9 passes through the brush 10 and extends into the powder tank 1 .

[0048] Furthermore, the brush 10 is used to brush away the dust adhering to the surface of the steel cable 9 after the detection action is completed, so as to keep the device clean and avoid the hysteresis of the mechanical action during the subsequent detection caused by the dust.

[0049] Preferably, the winding drum 5 is a columnar structure, and a ring-shaped winding groove is provided on the surface of the winding drum 5 , and the width of the winding groove is the same as the diameter of the steel cable 9 .

[0050] Furthermore, the width of the winding groove is the same as the diameter of the steel cable 9, ensuring that the steel cable 9 is in the same plane after being rolled up, and ensuring that the thickness of the steel cable 9 accurately corresponds to the number of turns of the steel cable 9.

[0051] Embodiment 2:

[0052] Preferably, the method for using the above-mentioned optomechanical level meter comprises the following steps:

[0053] S1, install the equipment on the top of the powder tank 1 to be tested, set the encoder and the Hall element current sensor at the motor 4; pull up the steel cable 9, make the solid ball 11 touch the travel switch 8, record the encoder angle at this time as the initial value, and record the distance data of the distance measuring device 6 at this time as the initial distance; then lower the steel cable 9, at this time the load provided by the solid ball 11 is large, and the current of the detected motor 4 is large;

[0054] S2, the steel cable 9 is continuously lowered so that the solid ball 11 contacts the highest point on the top of the material in the powder tank 1 and obtains support. The motor 4 loses the load of the solid ball 11. At this time, the current of the motor 4 suddenly decreases, and the Hall element current sensor sends the current magnitude signal to the main control chip 2. When the main control chip 2 detects that the current suddenly decreases sharply, it sends a trigger signal that the solid ball 11 reaches the top of the material in the powder tank 1, and records the number of encoder turns and angle at this time as the high material level value, and records the distance data of the distance measuring device 6 at this time as the high material level distance;

[0055] S3, continue to lower the steel cable 9, the solid ball 11 automatically slides down along the inclined surface at the top of the powder to the lowest point on the top of the material. During this process, the current signal may continue to oscillate. Continue to lower the steel cable 9 until the current signal is stable, which indicates that the solid ball 11 has touched the lowest point on the surface of the material. After the dwell time t, start the motor 4 to reverse and raise the steel cable 9. At first, the current is stable at a small value. When the steel cable 9 is completely straightened and the solid ball 11 is separated from the lowest point on the top of the material, the motor 4 obtains part or all of the load of the solid ball 11, and the current suddenly increases. The Hall element current sensor sends the current magnitude signal to the main control chip 2. The main control chip 2 sends a signal that the steel cable 9 has reached the lowest point on the top of the material, and records the number of turns and angle of the encoder as the low material level value, and records the distance data of the distance measuring device 6 as the low material level distance.

[0056] S4, during the process of S1 to S3, the knocking and sound pickup device 7 continuously knocks the steel cable 9 with a period T, and obtains the sound frequency data through the main control chip 2; when the steel cable 9 is loaded with the solid ball 11, the steel cable 9 is taut, and the frequency is high after knocking; when the steel cable 9 is lowered so that the solid ball 11 reaches the top of the material inside the powder tank 1 to obtain support, the steel cable 9 is relaxed, and the frequency is low after knocking. At this time, the main control chip 2 determines that the sound frequency suddenly becomes low as a signal that the steel cable 9 has reached the top of the material; when the steel cable 9 is raised, when the solid ball 11 leaves the lowest point of the top of the material, the steel cable 9 is taut again, and the frequency suddenly increases after knocking. The main control chip 2 determines that the sound frequency suddenly becomes high as a signal that the steel cable 9 has reached the lowest point of the top of the material;

[0057] S5, when the solid ball 11 reaches the highest point and the lowest point on the material surface, the main control chip 2 needs to obtain the current signal and the sound frequency signal at the same time. When the two determination signals are obtained at the same time, the detection action is determined to be qualified and the calculation program is run; otherwise, the detection action is determined to be invalid and an error is reported, and the above S~S are repeated for re-detection;

[0058] S6, the calculation procedure is as follows:

[0059] a. Count the number of turns and angles of the winding drum 5 through the angle feedback of the encoder; measure the distance change to the steel cable 9 on the winding drum 5 through the distance measuring device 6, thereby obtaining the thickness change of the steel cable 9 on the winding drum 5, and calculate the number of turns reduced by the steel cable 9 through the ratio of the distance to the diameter of the steel cable 9; determine whether the number of turns of the encoder is consistent with the number of turns measured and calculated by the distance measuring device 6; if not, reset the steel cable position to zero and re-measure; if consistent, execute the following step b;

[0060] b. Assume that the number of turns of the steel cable 9 on the winding drum 5 is n, the radius of the winding drum 5 is r, the diameter of the steel cable 9 is d, the rotation angle of the motor 4 is α, and the total height inside the powder tank 1 is H; then the length of the i-th turn of the full circle of steel cable = 2π*r+i*d;

[0061] The nth circle of steel rope does not make a complete circle, and its length = 2π*(α / 360-(n-1))*(r+n*d);

[0062] c.

[0063] d. Take the average of the length of the cable 9 when the cable 9 reaches the highest point of the silo material level and the length of the cable 9 when the cable 9 reaches the lowest point of the silo material level to obtain the material height, thereby avoiding errors caused by uneven material stacking.

[0064] Furthermore, the material level data is transmitted to the user end via the wireless communication module 3 .

[0065] Furthermore, the total height H in the powder tank 1 may be reduced by the diameter of the solid ball 11 itself as appropriate.

[0066] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. An optomechanical level meter, characterized in that: The invention comprises a powder tank (1), wherein a device box is arranged on the top of the powder tank (1), and a main control chip (2) is installed in the device box; a wireless communication module (3) is connected to the top of the device box and is electrically connected to the main control chip (2); a winding drum (5) is connected to a base on one side of the device box, and the winding drum (5) is connected to the output end of a motor (4); the winding drum (5) is connected to a mechanical detection mechanism via a steel cable (9); the mechanical detection mechanism comprises a fixed pulley block (12), one end of the steel cable (9) passes through the fixed pulley block (12) and is connected to a solid ball (11), and the solid ball (11) extends into the powder tank (1) through an opening at the top of the powder tank (1); The steel cable (9) is continuously lowered so that the solid ball (11) contacts the highest point of the top of the material in the powder tank (1); When the main control chip (2) detects that the current suddenly decreases sharply, it sends a trigger signal that the solid ball (11) reaches the top of the material in the powder tank (1), and records the number of encoder revolutions and angles at this time as the high material level value, and records the distance data of the distance measuring device (6) at this time as the high material level distance; The steel cable (9) is continuously lowered, and the solid ball (11) automatically slides down along the inclined surface at the top of the powder material to the lowest point at the top of the material. During this process, the current signal may continue to oscillate. The steel cable (9) is continuously lowered until the current signal is stable, which indicates that the solid ball (11) has contacted the lowest point on the surface of the material. After a dwell time t, the motor (4) is started to reverse and the steel cable (9) is raised. Initially, the current is stable at a relatively small value. When the steel cable (9) is completely stretched and the solid ball (11) is separated from the lowest point at the top of the material, the motor (4) obtains part or all of the load of the solid ball (11), and the current suddenly increases. The Hall element current sensor sends a current magnitude signal to the main control chip (2), and the main control chip (2) sends a signal indicating that the steel cable (9) has reached the lowest point at the top of the material, and records the number of turns and angle of the encoder at this time as the low material level value, and records the distance data of the distance measuring device at this time as the low material level distance; The material height is obtained by taking the average of the length of the steel cable (9) when the steel cable (9) reaches the highest point of the material level in the silo and the length of the steel cable (9) when the steel cable (9) reaches the lowest point of the material level in the silo.

2. The optical electromechanical level meter according to claim 1, characterized in that: A distance measuring device (6) is connected to one side of the main control chip (2), and the distance measuring device (6) faces the winding drum (5).

3. The optical electromechanical level meter according to claim 1, characterized in that: The mechanical detection mechanism comprises a knocking and sound-picking device (7) connected to the top of the powder tank (1), and the knocking and sound-picking device (7) cooperates with the steel cable (9).

4. The optical electromechanical level meter according to claim 1, characterized in that: The mechanical detection mechanism comprises a travel switch (8), the travel switch (8) being connected to the inner wall of the opening of the powder tank (1) through which the solid ball (11) passes, and the travel switch (8) and the knocking and sound pickup device (7) being electrically connected to the main control chip (2).

5. The optical electromechanical level meter according to claim 1, characterized in that: A brush (10) is connected to the surface of the powder tank (1) below the fixed pulley block (12), and the steel cable (9) passes through the brush (10) and extends into the powder tank (1).

6. The optical electromechanical level meter according to claim 1, characterized in that: The winding drum (5) is a columnar structure, and a ring-shaped winding groove is provided on the surface of the winding drum (5), wherein the width of the winding groove is the same as the diameter of the steel cable (9).

7. The method for using the optomechanical level meter according to claim 1, characterized in that: The following steps are also included: S1, installing the device on the top of the powder tank (1) to be tested, and setting an encoder and a Hall element current sensor at the motor (4); pulling up the steel cable (9) to make the solid ball (11) touch the travel switch (8), recording the encoder angle at this time as the initial value, and recording the distance data of the distance measuring device (6) at this time as the initial distance; then lowering the steel cable (9), at this time the load provided by the solid ball (11) is large, and the current of the detected motor (4) is large; S2, the steel cable (9) is continuously lowered so that the solid ball (11) contacts the highest point of the top of the material in the powder tank (1) and obtains support. The motor (4) loses the load of the solid ball (11). At this time, the current of the motor (4) suddenly decreases. The Hall element current sensor sends a current magnitude signal to the main control chip (2). When the main control chip (2) detects that the current suddenly decreases sharply, it sends a trigger signal that the solid ball (11) reaches the top of the material in the powder tank (1), and records the number of encoder revolutions and angles at this time as high material level values, and records the distance data of the distance measuring device (6) at this time as high material level distance; S3, continue to lower the steel cable (9), the solid ball (11) automatically slides down along the inclined surface at the top of the powder to the lowest point at the top of the material. During this process, the current signal may continue to oscillate. Continue to lower the steel cable (9) until the current signal is stable, which indicates that the solid ball (11) has contacted the lowest point on the surface of the material. After a stay time t, start the motor (4) to reverse and raise the steel cable (9). Initially, the current is stable at a relatively small value. When the steel cable (9) is completely stretched and the solid ball (11) is separated from the lowest point at the top of the material, the motor (4) obtains part or all of the load of the solid ball (11), and the current suddenly increases. The Hall element current sensor sends a current magnitude signal to the main control chip (2). The main control chip (2) sends a signal that the steel cable (9) has reached the lowest point at the top of the material, and records the number of turns and angle of the encoder at this time as the low material level value, and records the distance data of the distance measuring device at this time as the low material level distance; S4, during the process from S1 to S3, the knocking and sound pickup device (7) continuously knocks the steel cable (9) at a period T, and obtains sound frequency data through the main control chip; when the steel cable (9) is loaded with the solid ball (11), the steel cable (9) is taut, and the frequency after knocking is high; when the steel cable (9) is lowered so that the solid ball (11) reaches the top of the material inside the powder tank (1) for support, the steel cable (9) is relaxed, and the frequency after knocking is low. At this time, the main control chip (2) determines that the sound frequency suddenly decreases as a signal that the lowered steel cable (9) has reached the top of the material; when the steel cable (9) is raised, when the solid ball (11) is separated from the lowest point on the top of the material, the steel cable (9) is taut again, and the frequency after knocking suddenly increases. The main control chip (2) determines that the sound frequency suddenly increases as a signal that the lowered steel cable (9) has reached the lowest point on the top of the material; S5, when the solid ball (11) reaches the highest point and the lowest point on the surface of the material, the main control chip (2) needs to simultaneously obtain the current signal and the sound frequency signal. When both determination signals are obtained simultaneously, the detection action is determined to be qualified and the calculation program is run; otherwise, the detection action is determined to be invalid and an error is reported, and the above S1 to S4 are repeated to perform re-testing; S6, the calculation procedure is as follows: a. Count the number of turns and angles of the winding drum (5) by using the angle fed back by the encoder; measure the change in distance to the steel cable (9) on the winding drum (5) by using the distance measuring device (6), thereby obtaining the change in thickness of the steel cable (9) on the winding drum (5), and calculate the number of turns reduced by the steel cable (9) by using the ratio of the distance to the diameter of the steel cable (9); determine whether the number of turns of the encoder is consistent with the number of turns measured and calculated by the distance measuring device (6); if not, reset the steel cable position to zero and re-measure; if consistent, execute the following step b; b. Assume that the number of turns of the steel cable (9) on the winding drum (5) is n, the radius of the winding drum (5) is r, the diameter of the steel cable (9) is d, the rotation angle of the motor (4) is α, and the total height inside the powder tank (1) is H; then the length of the i-th turn of the full circle of steel cable = 2π*(r+ i*d); The nth circle of steel rope has not completed a full circle, and its length = 2π*(α / 360-(n-1))*(r+ n*d); c. Material level height = H- +2π*(α / 360-(n-1))*(r+ n*d); d. Take the average of the length of the steel cable (9) when the steel cable (9) reaches the highest point of the silo material level and the length of the steel cable (9) when the steel cable (9) reaches the lowest point of the silo material level to obtain the material height, thereby avoiding errors caused by uneven material accumulation.

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