Pressure measurement circuit, pressure sensor, pressure measurement system, hopper and apparatus

Abstract

The embodiment of the application discloses a kind of pressure measurement circuit, pressure sensor, pressure measurement system, material box and equipment, first connector and second connector are connected in pressure measurement circuit by positive line and negative line, first sampling module is connected with positive line, voltage stabilizing module and constant current module, first sampling module samples total current flowing into voltage stabilizing module to output first voltage signal to constant current module, strain pressure sensing module outputs second voltage signal to constant current module when strain gauge is subjected to external force, when the voltage of first voltage signal and second voltage signal is not equal, constant current module adjusts total current so that the voltage of first voltage signal is equal to the voltage of second voltage signal, the pressure acting on strain gauge can be calculated by the relationship between total current and the voltage of second voltage signal, without separately arranging signal line to collect the second voltage signal output by strain pressure sensing module of each pressure sensor.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a pressure measurement circuit, a pressure sensor, a pressure measurement system, a hopper, and a device. Background Technology

[0002] With the development of automatic control technology, drones and unmanned vehicles are used as unmanned plant protection equipment in agricultural plant protection operations. Unmanned vehicles and drones are usually equipped with plant protection materials such as fertilizers, seeds, and pesticides for plant protection operations.

[0003] During plant protection operations, plant protection equipment needs to know the current weight of materials in order to adjust the plant protection strategy. However, due to the special nature of plant protection equipment, the containers that carry plant protection materials are usually irregularly shaped, and the posture of the plant protection equipment changes in real time. Using a single pressure sensor to measure the weight of materials will result in a large error. If multiple pressure sensors are used to measure the weight of materials at multiple points, in addition to arranging power transmission lines for each pressure sensor, separate signal lines are also required to transmit the measurement signals of the pressure sensors, resulting in complex wiring on the plant protection equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a pressure measurement circuit, pressure sensor, pressure measurement system, material bin, and equipment to solve the problem of complex wiring for multi-point measurement of materials.

[0005] To achieve this objective, the embodiments of the present invention adopt the following technical solutions:

[0006] In a first aspect, a pressure measurement circuit is provided, comprising a first connector, a second connector, a first sampling module, a voltage stabilizing module, a strain pressure sensing module, and a constant current module.

[0007] The first connector and the second connector are connected via a positive wire and a negative wire. The first sampling module includes an input terminal, a sampling signal output terminal, and a power output terminal. The input terminal is connected to the positive wire, the power output terminal is connected to the input terminal of the voltage regulator module, the sampling signal output terminal is connected to the constant current module, and the output terminal of the voltage regulator module is connected to the power input terminal of the strain pressure sensing module and the power input terminal of the constant current module, respectively. The strain pressure sensing module includes a strain gauge and a sensing signal output terminal connected to the constant current module.

[0008] The first sampling module is used to sample the total current flowing into the voltage regulator module to output a first voltage signal to the constant current module. The strain pressure sensing module is used to output a second voltage signal to the constant current module when the strain gauge is subjected to an external force. The constant current module is used to adjust the total current so that the voltage of the first voltage signal is equal to the voltage of the second voltage signal when the voltages of the first voltage signal and the second voltage signal are not equal.

[0009] Optionally, the first sampling module includes a sampling unit and a first instrumentation amplifier. The input terminal of the sampling unit is connected to the positive line, the power output terminal of the sampling unit is connected to the input terminal of the voltage regulator module, the sampling signal output terminal of the sampling unit is connected to the input terminal of the first instrumentation amplifier, and the output terminal of the first instrumentation amplifier is connected to the input terminal of the constant current module as the sampling signal output terminal of the first sampling module.

[0010] Optionally, the sampling unit includes a first resistor, one end of which is connected to the positive line, and the other end of which serves as the power output terminal of the sampling unit and is connected to the input terminal of the voltage regulator module. The common node of the first resistor and the positive line is connected to the negative line in sequence through a second resistor and a third resistor. The common node of the first resistor and the input terminal of the voltage regulator module is connected to the negative line in sequence through a fourth resistor and a fifth resistor.

[0011] The common node of the second resistor and the third resistor is connected to the non-inverting input terminal of the first instrumentation amplifier, the common node of the fourth resistor and the fifth resistor is connected to the inverting input terminal of the first instrumentation amplifier, and the power input terminal of the first instrumentation amplifier is connected to the output terminal of the voltage regulator module.

[0012] Optionally, the strain pressure sensing module includes a strain gauge and a second instrumentation amplifier. The strain gauge includes a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor. One end of the seventh resistor is connected to the output terminal of the voltage regulator module, and the other end is connected to the negative line through the eighth resistor. One end of the ninth resistor is connected to the output terminal of the voltage regulator module, and the other end is connected to the negative line through the tenth resistor. The common node of the seventh and eighth resistors is connected to the non-inverting input terminal of the second instrumentation amplifier, and the common node of the ninth and tenth resistors is connected to the inverting input terminal of the second instrumentation amplifier. The power input terminal of the second instrumentation amplifier is connected to the output terminal of the voltage regulator module, and the output terminal of the second instrumentation amplifier serves as the sensing signal output terminal of the strain pressure sensing module and is connected to the input terminal of the constant current module.

[0013] Optionally, the constant current module includes a third amplifier and a transistor. The non-inverting input of the third amplifier is connected to the sensing signal output of the strain pressure sensing module through a twelfth resistor, and to the output of the voltage regulator module through a thirteenth resistor. The inverting input of the third amplifier is connected to the sampling signal output of the first sampling module. The power input of the third amplifier is connected to the output of the voltage regulator module. The output of the third amplifier is connected to the base of the transistor. The collector of the transistor is connected to the input of the voltage regulator module. The emitter of the transistor is connected to the negative terminal.

[0014] In a second aspect, a pressure sensor is provided, the pressure sensor comprising a pressure transmission device and a pressure measurement circuit as described in any one aspect of the first aspect, the pressure transmission device comprising:

[0015] The force-measuring shaft can withstand the force exerted by the object being measured.

[0016] A limiting device is provided, wherein the force measuring shaft passes through the limiting device and is slidably connected to the limiting device, and the limiting device is capable of balancing the radial force on the force measuring shaft;

[0017] The force measuring shaft can transmit the force exerted by the object under test on the force measuring shaft to the strain gauge to measure the pressure generated by the object under test on the force measuring shaft.

[0018] Optionally, the limiting device includes a limiting frame, the limiting frame having a through hole at its center, and the force measuring shaft movably passing through the through hole.

[0019] Optionally, a fixed cylinder is provided in the through hole on the limiting frame, and the force measuring shaft passes through the fixed cylinder and slides with the fixed cylinder.

[0020] Optionally, a linear bearing is provided in the through hole on the limiting frame, and the force measuring shaft is mounted on the limiting frame through the linear bearing.

[0021] Optionally, a fixing column is provided on the limiting frame, and the strain gauge is fixed on the fixing column.

[0022] Optionally, a first limiting part and a second limiting part are provided axially at intervals on the force measuring shaft, and the end of the strain gauge away from the fixed column is located between the first limiting part and the second limiting part. When the force measuring shaft is subjected to force and moves relative to the limiting frame, the first limiting part or the second limiting part can contact the strain gauge.

[0023] Optionally, the force measuring shaft is provided with a connecting part, and the strain gauge is connected to the connecting part.

[0024] Optionally, a first fixing block and a second fixing block are respectively provided on opposite sides of the limiting frame. The end of the strain gauge away from the connecting part is located between the first fixing block and the second fixing block. When the force measuring shaft moves relative to the limiting frame under force, the first fixing block or the second fixing block can contact the strain gauge.

[0025] Optionally, it also includes a seal, wherein one end of the force measuring shaft is provided with a first bearing plate and the other end is provided with a second bearing plate, and the seal is capable of filling the gap between the first bearing plate and the limiting frame, as well as the gap between the second bearing plate and the limiting frame.

[0026] Thirdly, a pressure measurement system is provided, including a power supply, a processor, a second sampling module, and a plurality of pressure sensors as described in any of the second aspects. The positive and negative terminals of the power supply are connected to a third connector. The plurality of pressure sensors are connected to the third connector after being connected in sequence through a first connector and a second connector. The positive terminal is connected to the third connector through the second sampling module. The sampling signal output terminal of the second sampling module is connected to the processor. The plurality of pressure sensors are distributed on the object to be measured.

[0027] The second sampling module is used to sample the current at the positive terminal of the power supply and output the sampled current value to the processor;

[0028] The processor is used to calculate the gravity of the object under test based on the sampled current value.

[0029] Optionally, the second sampling module includes a sampling resistor, a fourth amplifier, a filter, and an analog-to-digital converter module. The sampling resistor is connected in series between the positive terminal of the power supply and the third connector. The non-inverting input terminal and the inverting input terminal of the fourth amplifier are respectively connected to the two ends of the sampling resistor. The output terminal of the third amplifier is connected to the processor in sequence through the filter and the analog-to-digital converter module.

[0030] Fourthly, a material bin is provided, including a bin body and the pressure measuring system described in the third aspect; the pressure measuring system is disposed on the bin body and is used to detect the weight of the bin body.

[0031] Fifthly, a device is provided, comprising a device body, a hopper, and the pressure measurement system described in the third aspect; a pressure sensor in the pressure measurement system is disposed on the device body or the hopper and is used to detect the weight of the hopper.

[0032] In this embodiment of the invention, the pressure measurement circuit is applied to the pressure sensor. The first sampling module collects the total current of the entire circuit to output a first voltage signal. When an external force is applied to the strain gauge in the pressure sensing circuit, the strain pressure sensing module outputs a second voltage signal. The constant current module adjusts the total current of the entire pressure measurement circuit so that the voltage of the first voltage signal is equal to the voltage of the second voltage signal, thereby establishing a relationship between the total current and the second voltage signal output by the strain pressure sensing module. The second voltage signal is related to the pressure applied to the strain gauge. That is, the pressure can be calculated from the total current of the pressure measurement circuit. When measuring pressure at multiple points, multiple pressure sensors are connected in parallel to the power supply through connectors. The total current of the power supply is the sum of the total currents of each pressure sensor. The total pressure can be calculated from the total current of the power supply. There is no need to separately lay out signal lines to collect the second voltage signals output by the strain pressure sensing modules of each pressure sensor, which simplifies the wiring of the pressure measurement system. Furthermore, pressure sensors can be infinitely mounted at both ends of the power supply through connectors. Attached Figure Description

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0034] Figure 1 This is a structural block diagram of the pressure measurement circuit according to Embodiment 1 of the present invention;

[0035] Figure 2 This is a structural block diagram of the pressure measurement circuit according to Embodiment 2 of the present invention;

[0036] Figure 3 This is a circuit diagram of the pressure measurement circuit according to an embodiment of the present invention;

[0037] Figure 4 This is a force analysis diagram of the pressure sensor provided in an embodiment of the present invention;

[0038] Figure 5 This is a first cross-sectional view of the pressure sensor provided in Embodiment 3 of the present invention;

[0039] Figure 6 This is a second cross-sectional view of the pressure sensor provided in Embodiment 3 of the present invention;

[0040] Figure 7 This is a third cross-sectional view of the pressure sensor provided in Embodiment 3 of the present invention;

[0041] Figure 8 This is a first cross-sectional view of the pressure sensor provided in Embodiment 4 of the present invention;

[0042] Figure 9 This is a second cross-sectional view of the pressure sensor provided in Embodiment 4 of the present invention;

[0043] Figure 10 This is a third cross-sectional view of the pressure sensor provided in Embodiment 4 of the present invention;

[0044] Figure 11 This is a cross-sectional view of the pressure sensor provided in Embodiment 5 of the present invention;

[0045] Figure 12 This is an exploded view of the pressure sensor provided in Embodiment 5 of the present invention;

[0046] Figure 13 This is a schematic diagram of the pressure measurement system provided in Embodiment Six of the present invention;

[0047] Figure 14 This is a schematic diagram of the distribution of pressure sensors in the pressure measurement system provided in Embodiment Six of the present invention;

[0048] Figure 15 This is a structural block diagram of the second sampling module in Embodiment Six of the present invention.

[0049] In the picture:

[0050] 10. First connector; 20. Second connector; 30. First sampling module; 301. Sampling unit; 302. First instrumentation amplifier; 40. Voltage regulator module; 50. Strain pressure sensing module; 501. Strain gauge; 502. Second instrumentation amplifier; 60. Constant current module;

[0051] 1. Force measuring shaft; 11. First limiting part; 12. Second limiting part; 13. Connecting part; 14. First bearing plate; 15. Second bearing plate; 16. Connecting shaft; 17. Limiting shaft; 161. Connecting hole; 2. Limiting device; 21. Fixing column; 22. First fixing block; 23. Second fixing block; 4. Seal; 5. Linear bearing; 6. Housing; 61. Face cover; 62. Mounting hole; 7. Sealing ring; 8. Buffer; 9. Screw;

[0052] 100. Pressure sensor; 200. Power supply; 300. Second sampling module; 303. Sampling resistor; 304. Fourth amplifier; 305. Filter; 306. Analog-to-digital converter module; 400. Processor. Detailed Implementation

[0053] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a wireless communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] Example 1

[0056] Figure 1 This is a structural block diagram of the pressure measurement circuit according to Embodiment 1 of the present invention, as shown below. Figure 1 As shown, the pressure measurement circuit of this embodiment includes a first connector 10, a second connector 20, a first sampling module 30, a voltage stabilizing module 40, a strain pressure sensing module 50, and a constant current module 60.

[0057] The first connector 10 and the second connector 20 can be connectors with a positive line port and a negative line port, and the first connector 10 and the second connector 20 are connected by a positive line and a negative line.

[0058] The first sampling module 30 can be a circuit that samples the total current when the pressure measuring circuit is working. The voltage stabilizing module 40 can be a module that adjusts the voltage output by the first connector 10 to a stable working voltage. The strain pressure sensing module 50 includes a strain measuring plate. When the strain measuring plate is subjected to external force, the strain pressure sensing module 50 outputs a voltage signal. The constant current module 60 can adjust the total current when the pressure measuring circuit is working.

[0059] Specifically, the first sampling module 30 may include an input terminal, a sampling signal output terminal, and a power output terminal. The input terminal is connected to the positive line, the power output terminal is connected to the input terminal of the voltage regulator module 40, the sampling signal output terminal is connected to the constant current module 60, and the output terminal of the voltage regulator module 40 is connected to the power input terminals of the strain pressure sensing module 50 and the constant current module 60, respectively, to provide a stable operating voltage for the strain pressure sensing module 50 and the constant current module 60. The strain pressure sensing module 50 also includes a sensing signal output terminal connected to the constant current module 60.

[0060] The first sampling module 30 is used to sample the total current flowing into the voltage regulator module 40 to output a first voltage signal to the constant current module 60. The strain pressure sensing module 50 is used to output a second voltage signal to the constant current module 60 when the strain gauge is subjected to an external force. The constant current module 60 is used to adjust the total current flowing into the voltage regulator module 40 when the voltages of the first voltage signal and the second voltage signal are not equal, so that the voltage of the first voltage signal is equal to the voltage of the second voltage signal.

[0061] The working principle of the pressure measurement circuit in this embodiment of the invention is as follows:

[0062] When the first connector 10 is connected to the power supply, the first sampling module 30 samples the total current flowing into the voltage regulator module 40 and outputs a first voltage signal to the constant current module 60. This total current is the sum of the currents of the voltage regulator module 40, the strain pressure sensing module 50, and the constant current module 60. When the weight of the object under test acts as pressure on the strain gauge of the strain pressure sensing module 50, the strain pressure sensing module 50 outputs a second voltage signal to the constant current module 60. When the voltage of the first voltage signal and the voltage of the second voltage signal are not equal, the constant current module 60 adjusts the total current flowing into the voltage regulator module 40 to make the voltage of the first voltage signal and the voltage of the second voltage signal equal. This establishes the relationship between the total current and the second voltage signal. The second voltage signal is related to the pressure on the strain gauge. In other words, the pressure acting on the strain gauge, i.e., the weight of the object under test, can be calculated by sampling the total current of the pressure measurement circuit. There is no need to separately arrange signal lines to sample the second voltage signal output by the strain pressure sensing module 50 to calculate the weight of the object under test.

[0063] In this embodiment of the invention, the pressure measurement circuit is applied to the pressure sensor. The first sampling module collects the total current of the entire circuit to output a first voltage signal. When an external force is applied to the strain gauge in the pressure sensing circuit, the strain pressure sensing module outputs a second voltage signal. The constant current module adjusts the total current of the entire pressure measurement circuit so that the voltage of the first voltage signal is equal to the voltage of the second voltage signal, thereby establishing a relationship between the total current and the second voltage signal output by the strain pressure sensing module. The second voltage signal is related to the pressure applied to the strain gauge. That is, the pressure can be calculated from the total current of the pressure measurement circuit. When measuring pressure at multiple points, multiple pressure sensors are connected in parallel to the power supply through connectors. The total current of the power supply is the sum of the total currents of each pressure sensor. The total pressure can be calculated from the total current of the power supply. There is no need to separately lay out signal lines to collect the second voltage signals output by the strain pressure sensing modules of each pressure sensor, which simplifies the wiring of the pressure measurement system. Furthermore, pressure sensors can be infinitely mounted at both ends of the power supply through connectors.

[0064] Example 2

[0065] Embodiment 2 of the present invention is an optimization based on Embodiment 1, such as... Figure 2 As shown in the embodiment of the present invention, the first sampling module 30 includes a sampling unit 301 and a first instrumentation amplifier 302, and the strain pressure sensing module 50 includes a strain measuring plate 501 and a second instrumentation amplifier 502.

[0066] The input terminal of the sampling unit 301 is connected to the positive line, the power output terminal of the sampling unit 301 is connected to the input terminal of the voltage regulator module 40, the sampling signal output terminal of the sampling unit 301 is connected to the input terminal of the first instrumentation amplifier 302, and the output terminal of the first instrumentation amplifier 302 is connected to the input terminal of the constant current module 60 as the sampling signal output terminal of the first sampling module 30.

[0067] To enable those skilled in the art to more clearly understand the pressure measurement circuit of the embodiments of the present invention, the following is combined with... Figure 2 and Figure 3 The pressure measurement circuit is described below.

[0068] like Figure 3 As shown, in one example, the sampling unit 301 includes a first resistor R1. One end of the first resistor R1 is connected to the positive line, and the other end serves as the power output terminal of the sampling unit 301 and is connected to the input terminal Vin of the voltage regulator module 40. The current flowing through the first resistor R1 is the total current flowing into the voltage regulator module 40. The common node of the first resistor R1 and the positive line is connected to the negative line in sequence through the second resistor R2 and the third resistor R3. The common node of the first resistor R1 and the input terminal Vin of the voltage regulator module 40 is connected to the negative line in sequence through the fourth resistor R4 and the fifth resistor R5. The common node a of the second resistor R2 and the third resistor R3 is connected to the non-inverting input terminal of the first instrumentation amplifier U2. The common node b of the fourth resistor R4 and the fifth resistor R5 is connected to the inverting input terminal of the first instrumentation amplifier U2. The power input terminal of the first instrumentation amplifier U2 is connected to the output terminal Vout of the voltage regulator module 40. The output terminal of the first instrumentation amplifier U2 serves as the sampling signal output terminal of the first sampling module 30 and is connected to the input terminal of the constant current module 60.

[0069] The strain gauge 501 includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10. One end of the seventh resistor R7 is connected to the output terminal Vout of the voltage regulator module 40, and the other end is connected to the negative line through the eighth resistor R8. One end of the ninth resistor R9 is connected to the output terminal Vout of the voltage regulator module 40, and the other end is connected to the negative line through the tenth resistor R10. The common node e of the seventh resistor R7 and the eighth resistor R8 is connected to the non-inverting input terminal of the second instrumentation amplifier U3, and the common node f of the ninth resistor R9 and the tenth resistor R10 is connected to the inverting input terminal of the second instrumentation amplifier U3. The power input terminal of the second instrumentation amplifier U3 is connected to the output terminal of the voltage regulator module 40, and the output terminal of the second instrumentation amplifier U3 is connected to the input terminal of the constant current module 60 as the sensing signal output terminal of the strain pressure sensing module 50.

[0070] The constant current module 60 includes a third amplifier U4 and a transistor Q. The non-inverting input of the third amplifier U4 is connected to the sensing signal output of the strain pressure sensing module 50 through a twelfth resistor R12. Figure 3 As shown, the non-inverting input of the third amplifier U4 is connected to the output of the second instrumentation amplifier U3 through the twelfth resistor R12, and to the output Vout of the voltage regulator module 40 through the thirteenth resistor R13. The inverting input of the third amplifier U4 is connected to the sampling signal output of the first sampling module 30. Figure 3 As shown, the inverting input of the third amplifier U4 is connected to the output of the first instrumentation amplifier U2, the power input of the third amplifier U4 is connected to the output Vout of the voltage regulator module 40, the output of the third amplifier U4 is connected to the base of the transistor Q, the collector of the transistor Q is connected to the input Vout of the voltage regulator module 40 through resistor R16, and the emitter of the transistor Q is connected to the negative terminal.

[0071] like Figure 3 The working principle of the pressure measurement circuit shown is as follows:

[0072] When the first connector 10 is connected to the power supply, the current in the positive line flows into the input terminal Vin of the voltage regulator module 40 through the first resistor R1 and flows out at the output terminal Vout to provide operating voltage for the first instrumentation amplifier U2, strain gauge 501, second instrumentation amplifier U3 and third amplifier U4.

[0073] A voltage signal is acquired at one end of the first resistor R1 through the common node a of the second resistor R2 and the third resistor R3 and input to the non-inverting input of the first instrumentation amplifier U2. A voltage signal is acquired at the other end of the first resistor R1 through the common node b of the fourth resistor R4 and the fifth resistor R5 and input to the inverting input of the first instrumentation amplifier U2. This ensures that the voltage signal input to the first instrumentation amplifier U2 is within the input range of the first instrumentation amplifier U2. The output terminal of the first instrumentation amplifier U2 outputs a first voltage signal to the inverting input of the third amplifier U4. The voltage of the first voltage signal is V1out = K1 × I. 总 (K1 is the conversion factor, which can be adjusted by resistor R6 connected to the first instrumentation amplifier, I) 总 This refers to the current flowing through the first resistor R1, which is also the total current flowing into the voltage regulator module 40.

[0074] The strain gauge 501 is a full-bridge strain gauge, comprising a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10. When the strain gauge 501 deforms under pressure, the resistance values ​​of the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 change. The common node e of the seventh resistor R7 and the eighth resistor R8 outputs a voltage signal to the non-inverting input of the second instrumentation amplifier U3, and the common node f of the ninth resistor R10 and the tenth resistor R10 outputs a voltage signal to the inverting input of the second instrumentation amplifier U3. The output of the second instrumentation amplifier U3 outputs a second voltage signal to the non-inverting input of the third amplifier U4. The voltage of the second voltage signal is V2out = K2 × V. 压 (K2 is the conversion factor, which can be adjusted by resistor R11 connected to the second instrumentation amplifier, V) 压 (This refers to the voltage difference between common node e and common node f).

[0075] The main function of the constant current module 60 is to adjust the current I flowing through the first resistor R1 based on the voltage V2out of the amplified second voltage signal. 总 When the voltage V1out of the first voltage signal is not equal to the voltage V2out of the second voltage signal, the output voltage of the third amplifier U4 controls the transistor Q to turn on. After the transistor Q turns on, the total current I flowing through the first electron R1 increases. 总 The change causes a change in the voltage signals at the non-inverting and inverting input terminals of the first instrumentation amplifier U2. The voltage V1out of the first voltage signal output from the first instrumentation amplifier U2 becomes equal to the voltage V2out of the second voltage signal. Since the strain gauge 501 is not subjected to external force, the voltage V2out of the second voltage signal may be 0, while the current I flowing through the first resistor R1... 总Because the first instrumentation amplifier U2, the voltage regulator module 40, the second instrumentation amplifier U3, and the third amplifier U4 are all working, the current I flowing through the first resistor R1 is... 总 It is a value greater than 0. At this time, if the current I flowing through the first resistor R1 is... 总 Calculating the pressure applied to the strain gauge is inaccurate. Therefore, the input voltage at the non-inverting input of the third amplifier U4 must not be 0 and must be greater than the voltage V1out of the first voltage signal. Thus, the non-inverting input of the third amplifier U4 is connected to the output Vout of the voltage regulator module 40 through the thirteenth resistor R13. The voltage Vcc of the third amplifier U4 is also connected to the output Vout of the voltage regulator module 40, so that the input voltage V3+ = aV2out + bVcc at the non-inverting output of the third amplifier U4. The coefficients a and b can be changed by adjusting the twelfth resistor R12 and the thirteenth resistor R13. It is necessary to ensure that when V2out = 0, bVcc must be greater than the minimum value of V1out.

[0076] When the circuit is stable, we can conclude that:

[0077] V3+ = V3- = V1out;

[0078] V3+=aV2out+bVcc=a×(K2×V 压 )+bVcc;

[0079] V1out=K1×I 总 ;

[0080] That is, K1×I 总 =a×(K2×V) 压 )+bVcc;

[0081] I 总 =(a×(K2×V) 压 )+bVcc) / K1;

[0082] Since bVcc is a constant, it can be simplified to I. 总 =K 变 ×V 压 +C

[0083] That is, the current value I flowing through the first resistor R1 总 This includes the voltage difference V generated when the weight of the object being measured acts as pressure on the strain gauge. 压 This allows us to establish the relationship between the pressure acting on the strain gauge and I. 总 After establishing the correspondence, through I 总The weight of the object under test can be calculated, that is, the current value on the positive line is the representation of the weight of the object under test, without the need to arrange a separate signal line to collect the voltage V2out of the second voltage signal output when the strain gauge is under force.

[0084] In this embodiment of the invention, the pressure measurement circuit is applied to the pressure sensor. The first sampling module collects the total current of the entire circuit to output a first voltage signal. When an external force is applied to the strain gauge in the pressure sensing circuit, the strain pressure sensing module outputs a second voltage signal. The constant current module adjusts the total current of the entire pressure sensor so that the voltage of the first voltage signal is equal to the voltage of the second voltage signal, thereby establishing a relationship between the total current and the second voltage signal output by the strain pressure sensing module. The second voltage signal is related to the pressure applied to the strain gauge. That is, the pressure can be calculated from the total current of the pressure measurement circuit. When measuring pressure at multiple points, multiple pressure sensors are connected in parallel to the power supply through connectors. The total current of the power supply is the sum of the total currents of each pressure sensor. The total pressure can be calculated from the total current of the power supply. There is no need to separately lay out signal lines to collect the second voltage signals output by the strain pressure sensing modules of each pressure sensor, which simplifies the wiring of the pressure measurement system. Furthermore, pressure sensors can be infinitely connected at both ends of the power supply through connectors.

[0085] Example 3

[0086] like Figure 4 and Figure 5 As shown, this embodiment of the invention provides a pressure sensor that can be applied to multi-point distributed pressure measurement. The pressure sensor includes a pressure transmission device and a pressure measurement circuit provided in Embodiment 1 or Embodiment 2. The pressure transmission device includes a force measuring shaft 1 and a limiting device 2.

[0087] The force-measuring shaft 1 can withstand the force exerted by the object under test. The force-measuring shaft 1 passes through the limiting device 2 and is slidably connected to the limiting device 2. The limiting device 2 can balance and absorb the radial force on the force-measuring shaft 1. The force-measuring shaft 1 can transmit the force exerted by the object under test to the strain gauge 501 in the pressure measurement circuit to measure the pressure exerted by the object under test on the force-measuring shaft 1, that is, to measure the pressure parallel to the direction of the force-measuring shaft.

[0088] See Figure 4When the force-measuring shaft 1 is subjected to a force F from the object being measured, if the force F forms a certain angle with the axial direction of the force-measuring shaft 1, the force F will decompose into a vertical component f2 and a horizontal component f1. The vertical component f2 is along the axial direction of the force-measuring shaft 1, while the horizontal component f1 will cause the force-measuring shaft 1 to deflect, thus coming into contact with the limiting device 2. Since forces are mutual, the limiting device 2 will then generate a reaction force on the force-measuring shaft 1 to balance the horizontal component f1. Specifically, the force-measuring shaft 1 deflects and comes into contact with the upper and lower ends of the limiting device 2, generating reaction forces fh1 and fh2, respectively. According to force balance, f1 = fh1 + fh2. Simultaneously, the sliding connection between the force-measuring shaft 1 and the limiting device 2 can further reduce the frictional force fm along the axial direction of the force-measuring shaft 1 generated by fh1 and fh2, such as by using a linear bearing 5 to achieve the sliding connection between the force-measuring shaft 1 and the limiting device 2. Therefore, the force measuring shaft 1 will only transmit the vertical component force f2, that is, the final force fv = f2 experienced by the strain gauge 501. Thus, the pressure measured by the strain gauge 501 is the component force along the axial direction of the force measuring shaft 1 exerted by the object under test. If the force measuring shaft 1 is set in the vertical direction, then the pressure measured by the strain gauge 501 is the weight of the object under test.

[0089] In other words, strain gauge 501 will not measure the radial component of force generated by the interaction between the object under test and the force measuring shaft 1, thus ensuring the accuracy of the pressure sensor measurement results. Due to the presence of the limiting device 2, the pressure sensor can guarantee measurement accuracy without considering installation deviations during installation. The measurement results are not affected by other external forces, the installation requirements are low, and it is suitable for multi-point distributed measurement.

[0090] The pressure sensor provided in this embodiment is small in size and has low installation accuracy requirements, which can be used to achieve high-precision multi-point distributed measurement, effectively solving the problem that existing pressure sensors have high installation requirements and difficulty in guaranteeing measurement accuracy.

[0091] Specifically, when using this pressure sensor for measurement, it is only necessary to ensure that the force measuring axes 1 of multiple pressure sensors are parallel. Then, the sum of the forces on multiple pressure sensors is the pressure on the object to be measured in that direction, effectively avoiding interference from other component forces on the measurement results.

[0092] Furthermore, in the pressure sensor, the first sampling module collects the total current of the entire circuit to output a first voltage signal. When an external force is applied to the strain gauge in the pressure sensing circuit, the strain pressure sensing module outputs a second voltage signal. The constant current module adjusts the total current of the entire pressure sensor so that the voltage of the first voltage signal equals the voltage of the second voltage signal, thereby establishing a relationship between the total current and the second voltage signal output by the strain pressure sensing module. The second voltage signal is related to the pressure applied to the strain gauge. In other words, the pressure can be calculated from the total current of the pressure measurement circuit. When measuring pressure at multiple points, multiple pressure sensors are connected in parallel to the power supply through connectors. The total current of the power supply is the sum of the total currents of each pressure sensor. The total pressure can be calculated from the total current of the power supply without the need to separately lay signal lines to collect the second voltage signals output by the strain pressure sensing modules of each pressure sensor. On the one hand, this simplifies the wiring of the pressure measurement system and allows for the unlimited connection of pressure sensors at both ends of the power supply through connectors. On the other hand, calculating the pressure from the total current eliminates the need to calculate the pressure based on the second voltage signals output by the strain pressure sensing modules of each pressure sensor and then sum them up, reducing the amount of data processing and improving the efficiency of pressure measurement.

[0093] See Figure 5 and Figure 12 Optionally, the limiting device 2 includes a limiting frame, which is connected to the housing 6 of the pressure sensor. After the pressure sensor is installed and fixed, the position of the limiting frame is fixed. A through hole is provided in the center of the limiting frame, through which the force-measuring shaft 1 movably passes. That is, when the force-measuring shaft 1 is subjected to force, it can move up and down relative to the limiting frame. The limiting frame only restricts the radial movement of the force-measuring shaft 1, but does not restrict the axial movement of the force-measuring shaft 1.

[0094] like Figure 5 As shown, a fixed post 21 is provided on the limiting frame, and the strain gauge 501 is fixed on the fixed post 21. When the pressure sensor is fixed, the position of the strain gauge 501 is fixed. When the force measuring shaft 1 is subjected to the force of the object to be measured, the force along the axial direction of the force measuring shaft 1 can be transmitted to the strain gauge 501, so that the strain gauge 501 can accurately measure the component force along the axial direction of the force measuring shaft 1 exerted by the object to be measured on the force measuring shaft 1.

[0095] Optionally, a first limiting part 11 and a second limiting part 12 are provided axially at intervals on the force measuring shaft 1, and the end of the strain gauge 501 away from the fixing post 21 is located between the first limiting part 11 and the second limiting part 12. In this embodiment, a through hole is provided in the center of the strain gauge 501, through which the force measuring shaft 1 passes. The strain gauge 501 is located between the first limiting part 11 and the second limiting part 12, and both opposite sides of the strain gauge 501 are fixed to the limiting frame by the fixing post 21 to ensure that the strain gauge 501 is firmly installed. When the force measuring shaft 1 is subjected to force and moves downward relative to the limiting frame, the first limiting part 11 contacts the strain gauge 501, and the strain gauge 501 deforms, thereby measuring the weight of the object to be measured. If the force measuring shaft 1 is subjected to force and moves upward relative to the limiting frame, the second limiting part 12 can contact the strain gauge 501, and the strain gauge 501 deforms, thus also measuring the weight of the object to be measured.

[0096] In this embodiment, as Figure 5 and Figure 6 As shown, both the first limiting part 11 and the second limiting part 12 protrude from the force measuring shaft 1. In other embodiments, such as Figure 7 As shown, a groove can also be made along the circumferential direction on the force measuring shaft to form a first limiting part 11 and a second limiting part 12. One end of the strain measuring plate 501 is located in the groove, which can also realize the measurement of the weight of the object to be measured.

[0097] Optionally, a linear bearing 5 is provided in the through hole on the limiting frame, and the force measuring shaft 1 is mounted on the limiting frame through the linear bearing 5. Specifically... Figure 7 In the design, a linear bearing 5 is installed in each of the through holes at the upper and lower ends of the limiting frame. The outer shell of the linear bearing 5 is fixed to the inner wall of the through hole. The force-measuring shaft 1 slides with the inner ring of the linear bearing 5. The linear bearing 5 can further limit the radial direction of the force-measuring shaft 1, thereby balancing the horizontal component force on the force-measuring shaft 1 and further improving the measurement accuracy of the pressure sensor. Typically, a high-quality linear bearing 5 can have a friction coefficient as low as 0.001, which can significantly reduce the influence of the horizontal component force on the measurement results.

[0098] In another embodiment, optionally, a fixed cylinder is provided in the through hole of the limiting frame, and the force measuring shaft 1 passes through the fixed cylinder and slides with the fixed cylinder. Specifically, a fixed cylinder is provided in each of the upper and lower through holes of the limiting frame, the outer wall of the fixed cylinder is fixedly connected to the inner wall of the through hole, and the force measuring shaft 1 slides with the inner wall of the fixed cylinder. The fixed cylinder can further limit the radial direction of the force measuring shaft 1, balance the horizontal component of the force measuring shaft 1, and ensure that the strain gauge 501 can only detect the force in the vertical direction, thereby improving the measurement accuracy. Furthermore, lubricating oil can be coated between the force measuring shaft 1 and the solid cylinder to reduce the sliding friction between them, thereby reducing the influence of the force between the fixed cylinder and the measuring shaft on the measurement results.

[0099] like Figure 6 As shown, optionally, the pressure sensor also includes a seal 4, a first bearing plate 14 is provided at one end of the force measuring shaft 1, and a second bearing plate 15 is provided at the other end. Both the first bearing plate 14 and the second bearing plate 15 can withstand the force exerted by the object being measured. Figure 6 In this embodiment, the seal 4 fills the gap between the first bearing plate 14 and the limiting frame, as well as the gap between the second bearing plate 15 and the limiting frame. That is, in this embodiment, the seal 4 only fills the gap between the first bearing plate 14 and the second bearing plate 15 and the limiting frame, and does not fill the gap between the force-measuring shaft 1 and the limiting frame. Therefore, the seal 4 does not obstruct the relative sliding between the force-measuring shaft 1 and the limiting frame. In other embodiments, such as... Figure 7 As shown, the seal 4 can also be a ring structure, which is sleeved on the force measuring shaft 1. The limiting device 2 is provided with a sealing groove, and the seal 4 is located in the sealing groove. The seal 4 can prevent dust or water from entering the interior of the limiting frame, ensuring measurement accuracy. At the same time, it makes the pressure sensor dustproof and waterproof, so that the pressure sensor can be installed in environments with water and dust, thus expanding its application range.

[0100] Optionally, the seal 4 is made of rubber. Since the deformation of the strain gauge 501 is less than 50 μm, meaning the vertical movement of the force-measuring shaft 1 is extremely small, the force generated between the rubber and the limiting frame is negligible. In other words, the seal 4 does not affect the vertical movement of the force-measuring shaft 1 and has no impact on the measurement results of the strain gauge 501.

[0101] In other embodiments, the seal 4 can also be made of epoxy resin. Specifically, epoxy resin can be filled between the limiting frame and the first bearing plate 14 and the second bearing plate 15 to seal the gap. When applying the resin, care should be taken not to allow it to flow into the gap between the limiting frame and the force measuring shaft 1. Since the deformation of the strain gauge 501 is less than 50 μm, the force between the epoxy resin and the limiting frame can be ignored. Using a suitable epoxy resin can reduce the impact on measurement accuracy to less than 1g, and the impact on measurement accuracy caused by the epoxy resin can be calibrated.

[0102] Example 4

[0103] like Figure 8 and Figure 9 As shown, this embodiment provides a pressure sensor, wherein components that are the same as or corresponding to those in Embodiment 3 are labeled with the same reference numerals as those in Embodiment 3. For simplicity, only the differences between Embodiment 4 and Embodiment 3 are described. The differences are as follows:

[0104] Optionally, see Figure 8 and Figure 9A connecting part 13 is provided on the force measuring shaft 1, and the strain gauge 501 is connected to the connecting part 13. That is, when the force measuring shaft 1 moves up and down relative to the limiting frame, the strain gauge 501 moves along with the force measuring shaft 1. Further, a first fixing block 22 and a second fixing block 23 are respectively provided on opposite sides inside the limiting frame, and the end of the strain gauge 501 away from the connecting part 13 is located between the first fixing block 22 and the second fixing block 23. Specifically... Figure 7 In the design, a first fixing block 22 and a second fixing block 23 are respectively installed on the top and bottom surfaces of the inner limiting frame, with a certain distance between them. A strain gauge 501 is located between the first fixing block 22 and the second fixing block 23. When the force-measuring shaft 1 is subjected to force and moves downward relative to the limiting frame, the second fixing block 23 contacts the strain gauge 501, causing the strain gauge 501 to deform, thus measuring the weight of the object being measured. If the force-measuring shaft 1 is subjected to force and moves upward relative to the limiting frame, the first fixing block 22 contacts the strain gauge 501, causing the strain gauge 501 to deform, similarly allowing the measurement of the weight of the object being measured.

[0105] In another embodiment, such as Figure 10 As shown, the strain gauge 501 can also be directly fixed to the force measuring shaft 1. The limiting device 2 has a mounting cavity for the force measuring shaft 1 inside. Grooves are opened on both sides of the mounting cavity to form a first fixing block 22 and a second fixing block 23. One end of the strain gauge 501 is located in the groove, which can also realize the measurement of the weight of the object to be measured.

[0106] The pressure sensor in this embodiment is small in size and has low installation requirements, and can be used to achieve high-precision multi-point distributed measurement.

[0107] Example 5

[0108] like Figure 11 and Figure 12 As shown, this embodiment provides a pressure sensor, wherein components that are the same as or corresponding to those in Embodiment 3 are labeled with the same reference numerals as those in Embodiment 3. For simplicity, only the differences between Embodiment 5 and Embodiment 3 are described. The differences are as follows:

[0109] Optionally, the force-measuring shaft 1 includes a detachably connected connecting shaft 16 and a limiting shaft 17. The limiting shaft 17 is located within the through hole of the limiting device 2, and a linear bearing 5 is sleeved on the limiting shaft 17. The connecting shaft 16 can be connected to the object to be measured so as to measure the weight of the object through the force-measuring shaft 1 and the strain gauge 501. In this embodiment, a connecting hole 161 is provided in the center of the connecting shaft 16, and an internal thread is provided in the connecting hole 161. An extension shaft is provided at one end of the limiting shaft 17, and an external thread is provided on the extension shaft. One end of the extension shaft can be screwed into the connecting hole 161 to achieve a detachable connection between the connecting shaft 16 and the limiting shaft 17. Designing the connecting shaft 16 and the limiting shaft 17 to be detachably connected facilitates the installation of the strain gauge 501. In addition, the connecting shaft 16 can be connected to the object to be measured through the connecting hole 161.

[0110] Further, see Figure 11 and Figure 12 A buffer element 8 is sleeved on the extension shaft. The buffer element 8 includes a cylindrical body with buffer pads at both ends. One end of the strain gauge 501 is located between the two buffer pads. When the force measuring shaft 1 moves up and down relative to the limiting device 2 under force, the buffer element 8 can buffer the connecting shaft 16 and the limiting shaft 17, preventing the interaction between the connecting shaft 16 and the limiting shaft 17 from affecting the measurement results of the strain gauge 501. The buffer element 8 can be made of a material with buffering properties, such as rubber.

[0111] like Figure 11 and Figure 12 As shown, optionally, the strain gauge 501 is fixed to the fixing post 21 of the limiting device 2 by screws 9, making installation and disassembly convenient. Further, a face cover 61 is provided on the housing 6 of the pressure sensor, and the face cover 61 is also fixed to the housing 6 by screws 9. A sealing ring 7 is provided at the connection between the face cover 61 and the housing 6 to ensure a sealed connection between the face cover 61 and the housing 6, improving the waterproof and dustproof performance of the pressure sensor. A hole is provided on the face cover 61, through which the connecting shaft 16 passes. The sealing element 4 has an annular structure and is sleeved on the connecting shaft 16 to achieve a sealed connection between the connecting shaft 16 and the face cover 61.

[0112] Optionally, the housing 6 is also provided with a mounting hole 62, through which the pressure sensor can be fixed at the position to be measured.

[0113] Example 6

[0114] Figure 13 The diagram shown is a structural block diagram of the pressure measurement system according to Embodiment Six of the present invention. Figure 13 As shown, a pressure measurement system according to an embodiment of the present invention is used to measure the weight of an object to be measured. The pressure measurement system includes a power supply 200, a processor 400, a second sampling module 300, and a plurality of pressure sensors 100 in any one of embodiments three to five.

[0115] The positive and negative terminals of the power supply 200 are connected to the third connector. Multiple pressure sensors 100 are connected to the third connector in sequence through the first and second connectors. The positive terminal of the power supply 200 is connected to the third connector through the second sampling module 300. The sampling signal output terminal of the second sampling module 300 is connected to the processor 400. The multiple pressure sensors 100 are distributed on the object under test. The second sampling module 300 is used to sample the current at the positive terminal of the power supply 200 and output the sampled current value to the processor 400. The processor 400 is used to calculate the gravity of the object under test based on the sampled current value.

[0116] Specifically, such as Figure 14 As shown, multiple pressure sensors 100 (P1-P10) are provided on the irregularly shaped container A. The multiple pressure sensors 100 can be connected end to end in sequence through the first connector and the second connector in the pressure measurement circuit, and connected to the positive and negative terminals of the power supply 200 through the third connector. For example, taking pressure sensors P1-P10 as an example, the first connector of pressure sensor P1 is connected to the third connector on the power supply 200, the first connector of pressure sensor P2 is connected to the second connector of pressure sensor P1, the first connector of pressure sensor P3 is connected to the second connector of pressure sensor P2, and so on.

[0117] When fertilizer, plant seeds, medicine, and other materials are loaded into the irregularly shaped container A, the container deforms. The current flowing through the pressure sensor 100 at different positions is different under this deformation, and the sum of the currents of all pressure sensors 100 is the current at the positive terminal of the power supply 200.

[0118] like Figure 15 As shown, the second sampling module 300 includes a sampling resistor 303, a fourth amplifier 304, a filter 305, and an analog-to-digital converter 306. The sampling resistor 303 is connected in series between the positive terminal of the power supply 200 and the third connector. The non-inverting input terminal and the inverting input terminal of the fourth amplifier 304 are respectively connected to the two ends of the sampling resistor 303. The output terminal of the fourth amplifier 304 is connected to the processor 400 through the filter 305 and the analog-to-digital converter 306 in sequence. Specifically, the current flowing through the sampling resistor 303 is the sum of the currents of each pressure sensor 100. After the fourth amplifier 304 amplifies the collected current signal, it is input to the filter 305 to remove the noise signal. After the analog signal is converted into a data signal by the analog-to-digital converter 306, it is input to the processor 400. The processor 400 calculates the gravity of the object under test based on the current value flowing through the second sampling module 300.

[0119] like Figure 14As shown, the weight of the object to be measured, loaded in the irregularly shaped container A, is G = f1 + f2 + f3 + ... + fn, where fi is... Figure 14 The weight of the object being measured, which is borne by the pressure sensor Pi, is determined by the weight measured by each pressure sensor, f = K. 感 ×V 压 , where K 感 is the conversion factor, is a circuit property of the pressure sensor, and is a known quantity.

[0120] As can be seen from Example 2, I 总 =K 变 ×V 压 +C, then we can deduce:

[0121] f = K 感 ×(I 总 –C) / K 变

[0122] After substitution and simplification, we can obtain G = K × I – C, where K is a constant representing the attribute parameters of all pressure sensors in the entire pressure measurement system, which can be determined when the measurement system leaves the factory, the constant C is obtained by no-load measurement when using the measurement system, and I is the current at the positive terminal of the power supply 200 obtained by sampling.

[0123] Specifically, for K, we can first record the pressure value G calculated by processor 400 when the irregularly shaped container A is unloaded. 空 Then, multiple standard weights are placed sequentially into the irregularly shaped container A, and the pressure value G calculated by the processor 400 is recorded each time a weight is placed. i via G 空 Multiple G i To fit K, write K into processor 400.

[0124] For a constant C, under no-load conditions, record the resistance I that samples the current flowing through it. 空 C = K × I 空 .

[0125] In the pressure measurement system of this invention, each pressure sensor is connected by a power line. The weight of the object to be measured can be calculated by sampling the current value on the power line. There is no need to lay out a separate signal line for each pressure sensor to collect the sensing signal of the pressure sensor, which simplifies the wiring of the pressure measurement system. Furthermore, there is no need to calculate the weight measured by each pressure sensor and then sum them up, which reduces the amount of data processing and improves the efficiency of gravity measurement.

[0126] Example 7

[0127] In Embodiment Seven of the present invention, a material bin is also provided, including a bin body and the pressure measuring system described in Embodiment Six. The pressure measuring system is disposed on the bin body and is used to detect the weight of the bin body. The pressure sensors in the pressure measuring system can be evenly disposed at the bottom of the bin body or evenly disposed around the outer periphery of the bin body, as long as pressure can be applied to each pressure sensor in the direction of the bin body weight when measuring the weight of the bin body.

[0128] Example 8

[0129] In Embodiment 8 of the present invention, a device is also provided, which includes a device body, a material bin, and the pressure measurement system described in Embodiment 6. A pressure sensor in the pressure measurement system is installed on the device body or the material bin to detect the weight of the material bin, thereby determining the weight of the remaining material in the bin and enabling the device to control its operating status.

[0130] The equipment may include, but is not limited to, one of the following: agricultural drones, unmanned vehicles, unmanned boats, etc., which require the detection of the amount of remaining material in the material bin during operation.

[0131] In the description of this article, the terms "first" and "second" are used only to distinguish between them in the description and have no special meaning.

[0132] In the description of this specification, references to terms such as "an embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0133] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for the purpose of clarifying the device. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0134] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A pressure measuring circuit, characterized in that, It includes a first connector, a second connector, a first sampling module, a voltage regulator module, a strain pressure sensing module, and a constant current module. The first connector and the second connector are connected via a positive wire and a negative wire. The first sampling module includes an input terminal, a sampling signal output terminal, and a power output terminal. The input terminal is connected to the positive wire, the power output terminal is connected to the input terminal of the voltage regulator module, the sampling signal output terminal is connected to the constant current module, and the output terminal of the voltage regulator module is connected to the power input terminal of the strain pressure sensing module and the power input terminal of the constant current module, respectively. The strain pressure sensing module includes a strain gauge and a sensing signal output terminal connected to the constant current module. The first sampling module is used to sample the total current flowing into the voltage regulator module to output a first voltage signal to the constant current module. The strain pressure sensing module is used to output a second voltage signal to the constant current module when the strain gauge is subjected to an external force. The constant current module is used to adjust the total current so that the voltage of the first voltage signal is equal to the voltage of the second voltage signal when the voltages of the first voltage signal and the second voltage signal are not equal.

2. The pressure measuring circuit as described in claim 1, characterized in that, The first sampling module includes a sampling unit and a first instrumentation amplifier. The input terminal of the sampling unit is connected to the positive line, the power output terminal of the sampling unit is connected to the input terminal of the voltage regulator module, the sampling signal output terminal of the sampling unit is connected to the input terminal of the first instrumentation amplifier, and the output terminal of the first instrumentation amplifier is connected to the input terminal of the constant current module as the sampling signal output terminal of the first sampling module.

3. The pressure measuring circuit as described in claim 2, characterized in that, The sampling unit includes a first resistor, one end of which is connected to the positive line, and the other end of which serves as the power output terminal of the sampling unit and is connected to the input terminal of the voltage regulator module. The common node of the first resistor and the positive line is connected to the negative line in sequence through a second resistor and a third resistor. The common node of the first resistor and the input terminal of the voltage regulator module is connected to the negative line in sequence through a fourth resistor and a fifth resistor. The common node of the second resistor and the third resistor is connected to the non-inverting input terminal of the first instrumentation amplifier, the common node of the fourth resistor and the fifth resistor is connected to the inverting input terminal of the first instrumentation amplifier, and the power input terminal of the first instrumentation amplifier is connected to the output terminal of the voltage regulator module.

4. The pressure measuring circuit as described in claim 1, characterized in that, The strain pressure sensing module further includes a second instrumentation amplifier. The strain gauge includes a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor. One end of the seventh resistor is connected to the output terminal of the voltage regulator module, and the other end is connected to the negative line through the eighth resistor. One end of the ninth resistor is connected to the output terminal of the voltage regulator module, and the other end is connected to the negative line through the tenth resistor. The common node of the seventh and eighth resistors is connected to the non-inverting input terminal of the second instrumentation amplifier, and the common node of the ninth and tenth resistors is connected to the inverting input terminal of the second instrumentation amplifier. The power input terminal of the second instrumentation amplifier is connected to the output terminal of the voltage regulator module, and the output terminal of the second instrumentation amplifier serves as the sensing signal output terminal of the strain pressure sensing module and is connected to the input terminal of the constant current module.

5. The pressure measuring circuit as described in any one of claims 1-4, characterized in that, The constant current module includes a third amplifier and a transistor. The non-inverting input of the third amplifier is connected to the sensing signal output of the strain pressure sensing module through a twelfth resistor, and to the output of the voltage regulator module through a thirteenth resistor. The inverting input of the third amplifier is connected to the sampling signal output of the first sampling module. The power input of the third amplifier is connected to the output of the voltage regulator module. The output of the third amplifier is connected to the base of the transistor. The collector of the transistor is connected to the input of the voltage regulator module. The emitter of the transistor is connected to the negative terminal.

6. A pressure sensor, characterized in that, The pressure sensor includes a pressure transmission device and a pressure measurement circuit as described in any one of claims 1-5, wherein the pressure transmission device includes: The force-measuring shaft can withstand the force exerted by the object being measured. A limiting device is provided, wherein the force measuring shaft passes through the limiting device and is slidably connected to the limiting device, and the limiting device is capable of balancing the radial force on the force measuring shaft; The force measuring shaft can transmit the force exerted by the object under test on the force measuring shaft to the strain gauge to measure the pressure generated by the object under test on the force measuring shaft.

7. The pressure sensor as described in claim 6, characterized in that, The limiting device includes a limiting frame, and a through hole is provided at the center of the limiting frame, through which the force measuring shaft movably passes.

8. The pressure sensor as described in claim 7, characterized in that, A fixed cylinder is provided in the through hole on the limiting frame, and the force measuring shaft passes through the fixed cylinder and slides with the fixed cylinder.

9. The pressure sensor as described in claim 7, characterized in that, A linear bearing is provided in the through hole on the limiting frame, and the force measuring shaft is mounted on the limiting frame through the linear bearing.

10. The pressure sensor as described in claim 7, characterized in that, The limiting frame is provided with a fixing column, and the strain gauge is fixed on the fixing column.

11. The pressure sensor as described in claim 10, characterized in that, The force measuring shaft is provided with a first limiting part and a second limiting part at axial intervals. The end of the strain gauge away from the fixed column is located between the first limiting part and the second limiting part. When the force measuring shaft is subjected to force and moves relative to the limiting frame, the first limiting part or the second limiting part can contact the strain gauge.

12. The pressure sensor as described in claim 7, characterized in that, The force measuring shaft is provided with a connecting part, and the strain gauge is connected to the connecting part.

13. The pressure sensor as described in claim 12, characterized in that, The limiting frame has a first fixing block and a second fixing block respectively on opposite sides. The end of the strain gauge away from the connecting part is located between the first fixing block and the second fixing block. When the force measuring shaft moves relative to the limiting frame under force, the first fixing block or the second fixing block can contact the strain gauge.

14. The pressure sensor as described in claim 7, characterized in that, It also includes a sealing element. One end of the force measuring shaft is provided with a first bearing plate, and the other end is provided with a second bearing plate. The sealing element can fill the gap between the first bearing plate and the limiting frame, as well as the gap between the second bearing plate and the limiting frame.

15. A pressure measurement system, characterized in that, The device includes a power supply, a processor, a second sampling module, and multiple pressure sensors as described in any one of claims 6-14. The positive and negative terminals of the power supply are connected to a third connector. The multiple pressure sensors are connected to the third connector after being connected in sequence through a first connector and a second connector. The positive terminal is connected to the third connector through the second sampling module. The sampling signal output terminal of the second sampling module is connected to the processor. The multiple pressure sensors are distributed on the object to be measured. The second sampling module is used to sample the current at the positive terminal of the power supply and output the sampled current value to the processor; The processor is used to calculate the gravity of the object under test based on the sampled current value.

16. The pressure measurement system as described in claim 15, characterized in that, The second sampling module includes a sampling resistor, a fourth amplifier, a filter, and an analog-to-digital converter module. The sampling resistor is connected in series between the positive terminal of the power supply and the third connector. The non-inverting input and the inverting input of the fourth amplifier are respectively connected to the two ends of the sampling resistor. The output of the fourth amplifier is connected to the processor in sequence through the filter and the analog-to-digital converter module.

17. A material bin, characterized in that, It includes a housing and a pressure measuring system as described in any one of claims 15-16; the pressure measuring system is disposed on the housing and is used to detect the weight of the housing.

18. A device, characterized in that, The device includes a main body, a hopper, and a pressure measurement system as described in any one of claims 15-16; the pressure sensor in the pressure measurement system is disposed on the main body or the hopper and is used to detect the weight of the hopper.

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