CN212030713U - Vehicle weighing detection circuit - Google Patents
Vehicle weighing detection circuit Download PDFInfo
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- CN212030713U CN212030713U CN202021046958.1U CN202021046958U CN212030713U CN 212030713 U CN212030713 U CN 212030713U CN 202021046958 U CN202021046958 U CN 202021046958U CN 212030713 U CN212030713 U CN 212030713U
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Abstract
The utility model provides a vehicle weighing detection circuit, including piezoelectric film sensor, charge amplifier, data collection station and industrial computer, piezoelectric film sensor, charge amplifier, data collection station and industrial computer electric connection in proper order, the charge amplifier includes charge amplification circuit, voltage follower, inverting amplification circuit and differential amplifier; the output end of the piezoelectric film sensor is connected with the input end of the charge amplifying circuit, the output end of the charge amplifying circuit is respectively connected with the input ends of the voltage follower and the reverse-phase amplifying circuit, the output end of the voltage follower is connected with the reverse-phase input end of the differential amplifier, the output end of the reverse-phase amplifying circuit is connected with the non-inverting input end of the differential amplifier, and the output end of the differential amplifier is connected with the data collector. The utility model discloses a circuit structure of difference amplification can effectively restrain charge amplifier's drift at zero point and noise interference, is favorable to improving the precision that the vehicle weighed and detected.
Description
Technical Field
The utility model relates to a vehicle weighing technology field especially relates to a vehicle detection circuitry that weighs.
Background
The overload overrun vehicle not only can bring serious destruction to current road surface and bridge, also can bring huge hidden danger for driving safety, and dynamic weighing system can effectively help the traffic department to remedy vehicle overload overrun phenomenon, and dynamic weighing system's core component is weighing sensor, uses mostly at present is piezoelectric film sensor, has that road surface excavation volume is little, response speed is fast, small and easily advantage such as installation.
The output signal of the piezoelectric film sensor is a charge signal, and since the resistance of the piezoelectric material is limited, the charge will leak slowly, and a charge amplifier and an impedance transformation are needed to amplify the signal and convert the signal into a voltage signal which is easy to measure. The noise of the charge amplifier mainly comes from input stage components and input cables, the interference of the circuit is mainly formed by coupling 50 Hz alternating current to an input end through a stray capacitor, the zero drift of the charge amplifier is mainly generated by offset voltage and offset current of an input stage differential transistor circuit, if the input stage adopts a field effect transistor, the input bias current is very small, and the offset voltage is the main reason of causing the zero drift. The charge amplifier adopted in the traditional vehicle weighing detection circuit cannot effectively inhibit the noise interference and the zero drift.
SUMMERY OF THE UTILITY MODEL
In view of this the utility model provides a vehicle detection circuitry that weighs to the problem that the charge amplifier who solves traditional vehicle detection circuitry that weighs can't effectively restrain noise interference and drift of zero point.
The technical scheme of the utility model is realized like this: a vehicle weighing detection circuit comprises a piezoelectric film sensor, a charge amplifier, a data collector and an industrial personal computer, wherein the piezoelectric film sensor, the charge amplifier, the data collector and the industrial personal computer are electrically connected in sequence;
the output end of the piezoelectric film sensor is connected with the input end of the charge amplifying circuit, the output end of the charge amplifying circuit is respectively connected with the voltage follower and the input end of the reverse-phase amplifying circuit, the output end of the voltage follower is connected with the reverse-phase input end of the differential amplifier, the output end of the reverse-phase amplifying circuit is connected with the non-inverting input end of the differential amplifier, and the output end of the differential amplifier is connected with the data collector.
Optionally, the charge amplifying circuit, the voltage follower, the inverting amplifying circuit, and the differential amplifier all use OPA128 chips.
Optionally, positive and negative power supply ends of the operational amplifier in the charge amplification circuit, the voltage follower, the inverting amplification circuit and the differential amplifier are all grounded through capacitors.
Optionally, the charge amplifying circuit includes an operational amplifier U1, a resistor R1, a resistor R2, and a capacitor C2;
the output end of the piezoelectric film sensor is connected with the inverting input end of an operational amplifier U1 through a resistor R1, the output end of the operational amplifier U1 is respectively connected with the voltage follower and the input end of the inverting amplifying circuit, the output end of the operational amplifier U1 is also connected with the inverting input end of an operational amplifier U1 through a resistor R2, the output end of the operational amplifier U1 is also connected with the inverting input end of the operational amplifier U1 through a capacitor C2, and the non-inverting input end of the operational amplifier U1 is grounded.
Optionally, the charge amplification circuit further includes a capacitor C1 and a capacitor C3, the capacitor C1 is connected between the output end of the piezoelectric film sensor and the inverting input end of the operational amplifier U1, and the capacitor C3 is connected in parallel with the resistor R1.
Optionally, the charge amplifying circuit further includes a resistor R3, and the non-inverting input terminal of the operational amplifier U1 is grounded via the resistor R3.
Optionally, the inverting amplifier circuit includes an operational amplifier U3, a resistor R4, a resistor R5, and a resistor R6;
the output end of the charge amplification circuit is connected with the inverting input end of an operational amplifier U3 through a resistor R4, the non-inverting input end of the operational amplifier U3 is grounded through a resistor R5, the output end of the operational amplifier U3 is connected with the non-inverting input end of the differential amplifier, and the output end of the operational amplifier U3 is further connected with the inverting input end of the operational amplifier U3 through a resistor R6.
The utility model discloses a vehicle detection circuitry that weighs has following beneficial effect for prior art:
(1) the charge amplifier of the vehicle weighing detection circuit of the utility model adopts a differential amplification circuit structure, can effectively inhibit the zero drift and noise interference of the charge amplifier, and is beneficial to improving the precision of vehicle weighing detection;
(2) the utility model discloses a charge amplification circuit is through inserting a plurality of electric capacities and resistance, can avoid charge amplification circuit's self-oscillation, prevent because of the offset voltage that the zero drift that the sensor internal resistance undersize produced, balanced fortune were put, further suppressed charge amplifier's drift at zero point and noise disturbance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a block diagram of the vehicle weighing detection circuit of the present invention;
fig. 2 is a circuit diagram of the charge amplifier of the present invention.
Description of reference numerals: 10-a charge amplification circuit; 20-a voltage follower; 30-an inverting amplifier circuit; 40-differential amplifier.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work all belong to the protection scope of the present invention.
As shown in fig. 1, the vehicle weighing detection circuit of the embodiment includes a piezoelectric film sensor, a charge amplifier, a data collector, and an industrial personal computer, where the piezoelectric film sensor, the charge amplifier, the data collector, and the industrial personal computer are sequentially electrically connected, and the charge amplifier includes a charge amplification circuit 10, a voltage follower 20, an inverting amplification circuit 30, and a differential amplifier 40.
Generally, a piezoelectric film sensor functions to convert a force signal into an electric charge signal and output it when a vehicle tire acts thereon; the charge amplifier is used for amplifying the charge signal collected by the sensor and converting the charge signal into a voltage signal; the data collector is responsible for converting the analog voltage signal amplified by the charge amplifier into a digital voltage signal, transmitting the digital voltage signal into the industrial personal computer, and then carrying out data processing and analysis by the industrial personal computer to obtain the weight of the vehicle. The specific circuit structures and principles of the piezoelectric film sensor, the data acquisition unit and the industrial personal computer in the embodiment are the same as those of the traditional scheme, and are not repeated herein.
Generally, the requirements of the operational amplifier mainly include high gain, high input impedance, low drift, and wide frequency band, and the output drift amount of the charge amplifier in this embodiment is only related to the input offset voltage, the input offset current, and the input bias current, and the influence of these factors must be considered to reduce the output drift. Based on the consideration of the above factors, the charge amplifying circuit 10, the voltage follower 20, the inverting amplifying circuit 30 and the differential amplifier 40 all adopt an operational amplifier circuit formed by OPA128 chips, and in order to prevent the influence of power supply fluctuation on signals, positive and negative power supply terminals of operational amplifiers in the charge amplifying circuit 10, the voltage follower 20, the inverting amplifying circuit 30 and the differential amplifier 40 are all grounded through capacitors.
Specifically, as shown in fig. 2, the charge amplifying circuit 10 includes an operational amplifier U1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1, and a capacitor C2, the output end of the piezoelectric film sensor is sequentially connected with the inverting input end of an operational amplifier U1 through a capacitor C1 and a resistor R1, the output end of the operational amplifier U1 is respectively connected with the input ends of the voltage follower 20 and the inverting amplifying circuit 30, the output end of the operational amplifier U1 is further connected with the common end of a capacitor C1 and a resistor R1 through a resistor R2, the output end of the operational amplifier U1 is further connected with the output end of the piezoelectric film sensor and the common end of a capacitor C1 through a capacitor C2, the non-inverting input end of the operational amplifier U1 is grounded through a resistor R3, the positive electrode + Vcc of the power supply end of the operational amplifier U1 is grounded through a capacitor C4, and the negative electrode-Vcc of the power supply end of the operational amplifier U1 is grounded through a capacitor C5. The operational amplifier U1, the resistor R1, the resistor R2, and the capacitor C2 constitute the most common charge amplifying circuit 10 in the conventional scheme; the resistor R1 can avoid burning out the operational amplifier U1 due to overlarge current, and has an input protection effect on the integrated operational amplifier; the resistor R3 is used for balancing the voltage detuning value brought by the bias current at the input end of the operational amplifier U1; the capacitor C1 is used for preventing zero drift caused by too small internal resistance of the piezoelectric film sensor; the capacitor C3 is used to avoid adding an additional pole to the charge amplifier circuit 10 and generating an additional phase shift of 90 ° by the resistor R1 and the input capacitor of the integrated operational amplifier, so that the charge amplifier circuit 10 is unstable and self-oscillation occurs.
The essence of the charge amplifying circuit 10 can be regarded as a negative feedback integrating amplifier, so the feedback capacitance should be selected as a feedback capacitance with large leakage resistance (e.g. thin film capacitance, polystyrene capacitance, etc.) and small adsorption effect (e.g. polystyrene capacitance, polycarbonate capacitor, etc.). The capacitor C2 is preferably a polystyrene capacitor in this embodiment. For the problem of capacitance, both the gain of the circuit is ensured and the interference of parasitic capacitance is avoided as much as possible, so that the capacitance can be neither too large nor too small. The capacitor C2 is preferably 0.01 μ F in this embodiment.
The voltage follower 20 comprises an operational amplifier U2, a capacitor C6 and a capacitor C7, wherein the output end of the operational amplifier U1 is connected with the non-inverting input end of the operational amplifier U2, the output end of the operational amplifier U2 is connected with the inverting input end of the differential amplifier 40, the output end of the operational amplifier U2 is also directly connected with the inverting input end of the operational amplifier U2 through a lead, the positive electrode + Vcc of the power supply end of the operational amplifier U2 is grounded through the capacitor C6, and the negative electrode-Vcc of the power supply end of the operational amplifier U2 is grounded through the capacitor C7. The connection structure of the operational amplifier U2 constitutes a conventional voltage follower, and the principle thereof will not be described in detail.
The inverting amplifying circuit 30 comprises an operational amplifier U3, a resistor R4, a resistor R5, a resistor R6, a capacitor C8 and a capacitor C9, wherein an output end of the operational amplifier U1 is connected with an inverting input end of an operational amplifier U3 through a resistor R4, a non-inverting input end of the operational amplifier U3 is grounded through a resistor R5, an output end of the operational amplifier U3 is connected with a non-inverting input end of a differential amplifier 40, an output end of the operational amplifier U3 is further connected with an inverting input end of an operational amplifier U3 through a resistor R6, a positive electrode + Vcc of a power supply end of the operational amplifier U3 is grounded through a capacitor C8, and a negative electrode-Vcc of the power supply end of the operational amplifier U3 is. The operational amplifier U3, the resistor R4, and the resistor R6 constitute the most basic inverting amplifier circuit, and the resistor R5 is used to balance the voltage mismatch value at the input terminal of the operational amplifier U3 caused by the bias current.
The differential amplifier 40 comprises an operational amplifier U4, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a capacitor C10 and a capacitor C11, wherein the output end of the operational amplifier U2 is connected with the inverting input end of the operational amplifier U4 through a resistor R7, the output end of the operational amplifier U3 is connected with the non-inverting input end of the operational amplifier U4 through a resistor R8, the inverting input end of the operational amplifier U4 and the common end of the resistor R7 are connected with the output end of the operational amplifier U4 through a resistor R10, the non-inverting input end of the operational amplifier U4 and the common end of the resistor R8 are grounded through a resistor R9, the output end of the operational amplifier U4 is further connected with the input end of the data collector, the positive pole Vcc + of the power supply end of the operational amplifier U4 is grounded through a capacitor C10, and the. The operational amplifier U4, the resistor R7, the resistor R8, the resistor R9, and the resistor R10 constitute a conventional differential amplifier, and the principle thereof is not described in detail.
When the charge amplifier works, the charge amplifying circuit 10 primarily amplifies the charge quantity output by the piezoelectric film sensor and converts the charge quantity into a voltage signal, the output voltage signal is divided into two paths, one path is subjected to voltage following by the voltage follower 20 and then input to the inverting input end of the differential amplifier 40, the other path is subjected to inverting amplification by the inverting amplifying circuit 30 and then input to the non-inverting input end of the differential amplifier 40, the differential amplifier 40 performs differential operation on the two paths of input voltage signals, and finally the acquired sensor signal is transmitted to the data acquisition unit.
The values of the respective elements in the charge amplifier of the present embodiment can be referred to fig. 2.
In the experimental verification of the embodiment, the voltage of the direct-current power supply selected for the integrated operational amplifier is 12V, a noise voltage signal with the frequency of 1 khz and the size of 0.01V is added to the input end, and an amplitude-frequency characteristic curve and a phase-frequency characteristic curve obtained through simulation show that the charge amplifier of the embodiment has a wide frequency response range and a good cut-off frequency, and can well inhibit zero drift and noise interference. The charge amplifier has very high amplification factor by observing the waveform of the output signal through the oscilloscope, can completely meet the application of the piezoelectric film sensor, and can reduce interference and signal drift.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A vehicle weighing detection circuit comprises a piezoelectric film sensor, a charge amplifier, a data collector and an industrial personal computer, wherein the piezoelectric film sensor, the charge amplifier, the data collector and the industrial personal computer are electrically connected in sequence, and the vehicle weighing detection circuit is characterized in that the charge amplifier comprises a charge amplification circuit (10), a voltage follower (20), an inverse amplification circuit (30) and a differential amplifier (40);
the output of piezoelectric film sensor with the input of charge amplifier circuit (10) links to each other, the output of charge amplifier circuit (10) is connected respectively voltage follower (20), the input of inverting amplifier circuit (30), the output of voltage follower (20) is connected the inverting input of differential amplifier (40), the output of inverting amplifier circuit (30) is connected the non inverting input of differential amplifier (40), the output of differential amplifier (40) is connected data collection station.
2. The vehicle weigh detection circuit of claim 1 wherein said charge amplifier circuit (10), said voltage follower (20), said inverting amplifier circuit (30) and said differential amplifier (40) all employ OPA128 chips.
3. The vehicle weigh detection circuit of claim 1 wherein positive and negative supply terminals of operational amplifiers in said charge amplification circuit (10), said voltage follower (20), said inverting amplification circuit (30) and said differential amplifier (40) are all connected to ground via capacitors.
4. The vehicle weigh detection circuit as in claim 1, wherein said charge amplification circuit (10) includes an operational amplifier U1, a resistor R1, a resistor R2, a capacitor C2;
the output end of the piezoelectric film sensor is connected with the inverting input end of an operational amplifier U1 through a resistor R1, the output end of the operational amplifier U1 is respectively connected with the voltage follower (20) and the input end of an inverting amplifying circuit (30), the output end of the operational amplifier U1 is also connected with the inverting input end of an operational amplifier U1 through a resistor R2, the output end of the operational amplifier U1 is also connected with the inverting input end of the operational amplifier U1 through a capacitor C2, and the non-inverting input end of the operational amplifier U1 is grounded.
5. A vehicle weigh detection circuit as in claim 4 wherein said charge amplification circuit (10) further includes a capacitor C1 and a capacitor C3, the capacitor C1 being connected between the output of said piezoelectric film sensor and the inverting input of an operational amplifier U1, the capacitor C3 being connected in parallel with a resistor R1.
6. The vehicle weigh detection circuit as in claim 4, wherein said charge amplification circuit (10) further includes a resistor R3, the non-inverting input of operational amplifier U1 being connected to ground via resistor R3.
7. The vehicle weigh detection circuit as in claim 1, wherein said inverting amplifier circuit (30) includes an operational amplifier U3, a resistor R4, a resistor R5, a resistor R6;
the output end of the charge amplification circuit (10) is connected with the inverting input end of an operational amplifier U3 through a resistor R4, the non-inverting input end of the operational amplifier U3 is grounded through a resistor R5, the output end of the operational amplifier U3 is connected with the non-inverting input end of the differential amplifier (40), and the output end of the operational amplifier U3 is also connected with the inverting input end of the operational amplifier U3 through a resistor R6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021046958.1U CN212030713U (en) | 2020-06-09 | 2020-06-09 | Vehicle weighing detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021046958.1U CN212030713U (en) | 2020-06-09 | 2020-06-09 | Vehicle weighing detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212030713U true CN212030713U (en) | 2020-11-27 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021046958.1U Active CN212030713U (en) | 2020-06-09 | 2020-06-09 | Vehicle weighing detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212030713U (en) |
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2020
- 2020-06-09 CN CN202021046958.1U patent/CN212030713U/en active Active
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Address after: Luan Science and Technology Park, No. 18, Jinyang 1st Road, Yangluo Development Zone, Xinzhou District, Wuhan City, Hubei Province 430000 Patentee after: Wuhan Lu'an Electronic Equipment Co.,Ltd. Address before: 430000 Wu Jiatian, Yangluo street, Xinzhou District, Hubei, Wuhan Patentee before: Wuhan Lu'an Electronic Equipment Co.,Ltd. |