CN201787958U - Multi-channel signal acquisition card of vibrating string type sensor and based on controller area network (CAN) bus - Google Patents

Abstract

The utility model discloses a multi-channel signal acquisition card of a vibrating string type sensor and based on a CAN bus. An excitation circuit module of a sensor is connected with the input end of a vibrating string type sensor through a multi-channel switching circuit module, a pick-up vibration circuit module of the sensor is connected with the output end of the vibrating string type sensor, the pick-up vibration circuit module of the sensor is connected with an equal-precision frequency measuring circuit module, and a CAN-bus communication circuit module sends out and receives frequency values between a main control unit and a system main control card through a bus transceiver. The main control unit controls the excitation circuit module of the sensor, the multi-channel switching circuit module, the equal-precision frequency measuring circuit module and the CAN-bus communication circuit module respectively through circuits. The acquisition card serving as an embedded smart cell can be freely combined with other sensor acquisition cards according to different application requirements to form a flexible hardware platform of an integrated data acquisition system, and be applied to projects of geotechnical engineering, bridge construction and the like.

Description

Hyperchannel vibrating string type sensor data acquisition card based on the CAN bus

Technical field:

The utility model relates to a kind of data acquisition card, relates in particular to a kind of hyperchannel vibrating string type sensor data acquisition card of the CAN of employing bus.

Background technology:

Sensor is penetrated into already such as the extremely general field of commercial production, space development, hydrospace detection, environmental protection, resource exploration, medical diagnosis, bioengineering even historical relic's protection or the like; this shows that sensor technology is in the vital role of developing the economy, promoting aspect the social progress.Existing sensors is of a great variety, and vibrating string type sensor is simple in structure, sturdy and durable with it, long-time stability are good, precision and resolution are high is celebrated, and is widely used in the engineerings such as Geotechnical Engineering, bridge construction.This sensor is output as frequency signal, and the extensible cable is convenient to long-distance transmissions, is subjected to gazing at of engineering circle always.But because vibrating string type sensor self, therefore make needs the general sensor complex of metering circuit to adopt instrumentation that it is measured.

External more representational vibrating wire sensor and the type vibration wire readout instrument thereof that the production of U.S. base Kanggong department is arranged, the domestic Golden Horse scientific ﹠ technical corporation that Changsha is arranged etc.But the vibrating wire sensor surveying instrument that these companies produce can only be measured vibrating wire sensor, and when needing polytype sensor that the different kinds of parameters of measurand is measured simultaneously, above-mentioned instrument then can not be realized in actual engineering.

The utility model content:

The utility model provides a kind of hyperchannel vibrating string type sensor data acquisition card based on the CAN bus at the deficiencies in the prior art.

For realizing above purpose, the technical solution adopted in the utility model is:

Based on the hyperchannel vibrating string type sensor data acquisition card of CAN bus, by sensor excitation chain module, sensor pick-up circuit module, etc. precision frequency measurement circuit module, CAN bus communication circuit module, hyperchannel commutation circuit module, main control unit form; Sensor excitation chain module links to each other with the vibrating string type sensor input end by hyperchannel commutation circuit module, the string wire vibration of the oscillator signal excitation vibrating string type sensor inside that sensor excitation chain module produces, output signal then; Sensor pick-up circuit module links to each other with the vibrating string type sensor output terminal, after the amplification of vibrating string type sensor output signal, shaping, obtains a standard square-wave signal; Sensor pick-up circuit module with etc. precision frequency measurement circuit module link to each other, will obtain precision frequency measurement circuit modules such as the standard square-wave signal is transferred to carries out frequency measurement; CAN bus communication circuit module is by bus transceiver transmitting-receiving frequency value between main control unit and system master card; Main control unit by circuit control respectively sensor excitation chain module, hyperchannel commutation circuit module, etc. precision frequency measurement circuit module and CAN bus communication circuit module, be respectively applied for whole capture card each several part circuit is realized control, be specially the exciting period T of adjusting sensor excitation chain module, control hyperchannel commutation circuit module is to the selection of passage, etc. precision frequency measurement circuit module to the measurement of frequency f and the work of control CAN bus communication circuit module.

Described sensor excitation chain module forms circuit, trigger circuit, signal input circuit by the 300V high-voltage pulse and forms.

Described main control unit adopts the 89S52 microprocessor.

The utility model compared with prior art has the following advantages: capture card can be divided into excitation chain, pick-up circuit, etc. precision frequency measurement circuit and adopt five modules of CAN bus communication circuit, hyperchannel commutation circuit based on SJA1000, the intelligent node design that has realized intercoming mutually with main control card has that institute's signal quality that obtains is good, measuring accuracy is high, measure many, the reliability advantages of higher of passage; Adopt the vibrating string type sensor data acquisition card as an embedded intelligence unit, can realize sensor acquisition card independent assortment, constitute an integrated data acquisition system hardware platform flexibly according to different application needs and other kinds.

Description of drawings:

Fig. 1 is the utility model theory diagram;

Fig. 2 is the utility model sensor excitation chain figure;

Fig. 3 is the utility model sensor pick-up circuit diagram;

Fig. 4 is precision frequency measurement circuit figure such as the utility model;

Fig. 5 is the utility model CAN bus communication circuit diagram;

Fig. 6 is the utility model hyperchannel commutation circuit figure;

Fig. 7 is the utility model main control unit circuit diagram;

Embodiment:

As shown in Figure 1, based on the hyperchannel vibrating string type sensor data acquisition card of CAN bus, by sensor excitation chain module 1, sensor pick-up circuit module 2, etc. precision frequency measurement circuit module 3, CAN bus communication circuit module 4, hyperchannel commutation circuit module 5, main control unit 6 form; Sensor excitation chain module 1 links to each other with the vibrating string type sensor input end by hyperchannel commutation circuit module 5, the string wire vibration of the oscillator signal excitation vibrating string type sensor inside that sensor excitation chain module 1 produces, output signal then; Sensor pick-up circuit module 2 links to each other with the vibrating string type sensor output terminal, and the vibrating string type sensor output signal is amplified, after the shaping, obtained a standard square-wave signal, precision frequency measurement circuit module 3 such as is transferred to then and carries out frequency measurement; CAN bus communication circuit module 4 is by bus transceiver transmitting-receiving frequency value between main control unit 6 and system master card, the effect of this circuit module is under Single-chip Controlling, the frequency values f that records is sent on the CAN bus, and main control card receives frequency values f by the CAN bus more then; Main control unit 6 by circuit control respectively sensor excitation chain module 1, hyperchannel commutation circuit module 5, etc. precision frequency measurement circuit module 3 and CAN bus communication circuit module 4, be respectively applied for whole capture card each several part circuit is realized control, be specially the exciting period T of adjusting sensor excitation chain module 1, the selection of 5 pairs of passages of control hyperchannel commutation circuit module is etc. the measurement of 3 pairs of frequency f of precision frequency measurement circuit module and the work of control CAN bus communication circuit module 4.

As shown in Figure 2, vibrating string type sensor is different with general sensor, needs to vibrate with its inner string wire of external excitation signal excitation earlier, then could output signal.Sensor excitation chain module 1 forms circuit, trigger circuit, signal input circuit by the 300V high-voltage pulse to be formed, and high-voltage pulse circuit is by Sheffer stroke gate U6A, U6C, the triode Q of band application schmitt trigger ₁, step-up pulse transformer T ₁, diode D ₁, D ₂Deng composition.Wherein the oscillator signal of oscillatory circuit generation is through triode Q ₁Driving after send into pulse transformer T ₁Elementary, by transformer boost, D ₅Rectification and to C ₃₃Charging, at C ₃₃Two ends form the 300V high pressure.

At C ₃₃When two ends formed the 300V high pressure, pulse transformer was secondary also through R ₆₀, C ₂₃, D ₁₉To C ₂₃Charging is at C ₂₃Two ends form the positive right negative 300V high pressure in a left side, no current in the vibrating wire sensor at this moment.When we at controllable silicon S ₁The control utmost point add trigger pip, make the controllable silicon conducting, then C ₂₃The electric charge at two ends is released rapidly through discharge loop, forms discharge current I ₂Because original C ₂₃Both end voltage is very high, so flow through the leakage current I of vibrating wire sensor ₂Also very big, thus very high-intensity magnetic field in magnetic core coil, produced, and with the string wire adhesive, current vanishes then string wire discharges, so string wire just vibrates.

The sensor input circuit is by vibrating wire sensor C ₃₄, R ₄, D ₁₉Forming, is a RLC charging and discharging circuit, and effect is the sine wave signal that forms after string wire vibrates.Principle of work is that this induced electromotive force passes through the RLC loop to C because string wire vibrates the back cutting magnetic line, and the string wire two ends have just produced induced electromotive force ₃₄Charging.After charging finishes, C ₃₄To the vibrating wire sensor discharge, form free oscillation again, thereby produce sine wave signal.Because there is resistance to exist in the RLC loop, so this sine wave is a progressively signal of decay, about about 2 seconds of duration.

As shown in Figure 3, because vibrating string type sensor exciting amplitude output signal is too low, its value is many between 300 μ V～1mV, is subject to extraneous interference, so adopt active band pass filter to signal filtering.Be generally the characteristics of 500HkHz～6kHz according to the frequency range of vibrating wire sensor signal, we are when the design active band pass filter, and band is logical, and to elect 0.4～7kHz as comparatively suitable.In addition because vibrating string type sensor exciting output signal is fainter, so U8C, U8A two-level operating amplifier amplify signal among the employing figure, send into the shaping circuit of forming by Schmidt trigger U5D then, obtain a standard square-wave signal after the shaping, precision frequency measurement circuit 3 such as deliver to and carry out frequency measurement.

As shown in Figure 4, Y3 is the active crystal oscillator of 20MHZ, provides timing pulse as standard frequency source.U3 is 8 digit counters, here uses as frequency divider, realizes measured signal f _OutThe counting frequency division.U21 is 8 digit counters, forms 24 digit counters jointly with TL0, TH0 among single-chip microcomputer internal timing/counter T0, and timing pulse is counted.U17 is a latch, realizes the data latching to counter U21, so that gone into by monolithic is machine-readable as the least-significant byte data.Single-chip microcomputer carries out calculation process to 24 bit data of reading in, and obtains frequency values f.

Be located at one-shot measurement in the time count value to measured signal be N ₁, be N to the count value of standard-frequency signal ₂, then following formula is set up N ₁T _x=N ₂T _r

So measured signal frequency f _x=N ₁f _r/ N ₂

The tested frequency f of measuring of resolution K= _x/ one-shot measurement is markers f in the cycle _rNumber

F for example _x=5KHZ, markers f _r=20MHZ, divide ratio N ₁=16, the resolution of Ce Lianging then

$K=\frac{f_x}{N_1(f_r/f_x)}\≈0.1\mathrm{Hz}$

As shown in Figure 5, this intelligent node partly is made up of microprocessor 89S52, CAN communication controler SJA1000, high-speed photoelectric coupler 6N137, CAN bus transceiver 82C250 etc.High-speed photoelectric coupler 6N137 has realized the electrical isolation between transceiver and the controller, protection intelligent node core circuit trouble free service, and realized the internodal electrical isolation of each CAN on the bus.CAN bus transceiver 82C250 provides differential transmittability as the interface between SJA1000 and the physical transfer circuit to bus, provides differential receiving ability to the CAN controller.

The effect of this circuit module is under Single-chip Controlling, and the frequency values f that records is sent on the CAN bus, and main control card receives frequency values f by the CAN bus more then.

As shown in Figure 6, this module is made up of 74LS138 code translator, U20 driving circuit and eight relays of U10, is used for eight of eight paths different vibrating string type sensors are switched, and realizes the circulation exciting and patrols survey.

As shown in Figure 7, main control unit 6 adopts the 89S52 microprocessor, is used for whole capture card each several part circuit is realized control.Be specially the exciting period T of adjusting excitation chain, control hyperchannel commutation circuit is to the selection of passage, the precision frequency measurement circuit such as also has to the measurement of frequency f and the work of control CAN bus communication circuit.

The utlity model has advantages such as rational in infrastructure, multiple functional, good stability, can be applicable to be equipped with wireless transmission function in the engineerings such as Geotechnical Engineering, bridge construction, also can realize remote measurement and monitoring, have great promotional value.

Claims (3)

1. based on the hyperchannel vibrating string type sensor data acquisition card of CAN bus, it is characterized in that: sensor excitation chain module links to each other with the vibrating string type sensor input end by hyperchannel commutation circuit module; Sensor pick-up circuit module links to each other with the vibrating string type sensor output terminal; Sensor pick-up circuit module with etc. precision frequency measurement circuit module link to each other; CAN bus communication circuit module is by bus transceiver transmitting-receiving frequency value between main control unit and system master card; Main control unit by circuit control respectively sensor excitation chain module, hyperchannel commutation circuit module, etc. precision frequency measurement circuit module and CAN bus communication circuit module.

2. the hyperchannel vibrating string type sensor data acquisition card based on the CAN bus according to claim 1 is characterized in that: described sensor excitation chain module forms circuit, trigger circuit, signal input circuit by the 300V high-voltage pulse and forms.

3. the hyperchannel vibrating string type sensor data acquisition card based on the CAN bus according to claim 1 is characterized in that: described main control unit adopts the 89S52 microprocessor.

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