Sensor assembly for structure health detection
Technical field
The present invention relates to structure detection sensor technical field, be particularly used for the sensor of structure health detection
Module.
Background technology
Structure health monitoring (Structural Health Monitoring, SHM) is defined as the damage to engineering structure
Wound monitoring and characteristic describe.This is a concept emerging over nearly 20 years.Its field being mainly absorbed in is the health of infrastructure
Situation, including building, bridge, tunnel and aircraft industry.Tubing (oil pipe, optical fiber etc.), at a high speed public affairs the most under water
Road, machinery, medical treatment and circuit board aspect also have related application.
2007, the U.S., I-35 highway bridge caved in due to over loading;2009, Germany, urban history archives by
Cave in ground deformation;The two case is all that the infrastructure caused owing to lacking structure health monitoring is caved in.Wherein
Building and bridge respectively due to ground deformation and excessive deformation and caving in of causing.One frame of U.S. Cleveland has made
By the old bridge on highway of 50 years.This bridge block was diagnosed main reinforcement and damages and excessively deformation in 2009.Afterwards,
It is removed at this bridge block in 2014 and rebuilds.
The typical perceptual parameters of sensor (measurement parameter) have strain, pressure, temperature, slope, humidity, burn into vibration,
Pressure and horizontality.These parameters are got by various sensor acquisition, including: anemometer, accelerometer, dynamic and static
Foil gauge, displacement transducer, temperature sensor, global positioning system, horizon sensor, dynamic weighing equipment, barometer, rainfall
Meter, drimeter, corrosion sensor, digital camera and electromagnetic transducer.
At present, due to high cost overhead, it is vital greatly that structure health monitoring systems is only applied only to some
On type bridge and important skyscraper.In numerous bridges as a example by the bridge of AngChuan Zhou, Hong Kong, this bridge is provided with wind
Power and structure health monitoring systems, be one of the most expensive digitized bridge.In terms of building, with
As a example by high Harry method tower.1723 monitoring sensor nodes are installed on the bridge of AngChuan Zhou, Hong Kong altogether.Wherein have 82%
The sensor of (1416) is foil gauge and temperature sensor.On the other hand, 428 foil gauges on Harry method tower it are arranged on.Right
For this type of vital structure, the high cost that installation total health monitoring system is brought is acceptable;And
For other major part bridge and building, first select the system of customization.The system of this customization only monitors part knot
Structure body parameter, thus reduce cost.A part of bridge of China uses the structure health monitoring systems of transformation so that it is can
Use mixed topology, such as, communication: optical fiber technically, wired or wireless;The energy: electric lines of force, battery, or energy acquisition;
Sensor type: active, or passive type (passive).
The case of U.S.'s bridge health diagnosis.The importance of structure health monitoring can be embodied by this example following
Out.From nineteen ninety, various places Public Security Department of the U.S. requires to visually inspect whole 576,000 high speed with half a year for the cycle
Bridge.Such detection is it can be found that the grade deformation of bridge, thus recalls the bridge that maintenance part structure is the most aging.This
The statistics of sample shows:
Initial stage nineteen ninety: the bridge (236,000) of the U.S. nearly 35% is structurally or the most defective;
2006: be structurally imperfect more than 149,000 bridge blocks;
2012: the bridge of similar 25% is defective.
It is emphasized that the groundwork amount of perception concentrates in strain measurement and temperature survey in monitoring system.
The main cause of bridge damage is overload (often being caused by heavy truck), high wind and earthquake.This needs periodically monitoring by this
The bridge deformation that a little reasons are caused.In the case of bridge on highway, to the importance of bridge deformation degree measurement be aobvious and
Be clear to only checks the degree that just can predict bridge damage by visually strain.Strain measurement assessment building settlement and
Tilt condition aspect also it is critical that, especially in the construction stage.
If structure health monitoring is extremely important in structural diagnosis, and also it is ready-made in Vehicles Collected from Market
, then problem is not have such system in the most important infrastructure?Here, main reasons is that it
High cost.In addition other reason includes high power consumption and the expense of high maintenance of system, especially powers or too at battery
In the case system that sun can be powered.System accuracy drift (being especially influenced by temperature) is still that a factor that cannot ignore.
Topological structure, quantity of perceptual parameters etc..Each sensor cost (cost per sensor) is assessment one
The good basis for estimation of monitoring system cost.Fig. 1 show the Cost comparisons of 4 bridge blocks, employs light in these bridges
Fibre and wireless monitor technology.Expensive cost is that automatic structure body health monitoring systems is only installed at the former of a small amount of important bridge
Cause.Chinese bridge estimated cost is probably at one to two million dollars.In the bridge being provided with automatic monitoring system, Mei Gechuan
The cost of sensor is probably at about 5000 dollars.
Power consumption (battery life) limits the development along with embedded type wireless sensing system in recent years, it appears that realize a high letter
The wireless topology body health monitoring systems of valency ratio is close at hand beyond doubt.Collaborative energy resource collecting technology (solar energy or vibrational energy
Amount) full-automatic solution can be realized.In order to preferably go to weigh the relation between cost and system, have studied some current
The state of development of the wireless monitor system disposed.
As a example by the precious island bridge (344 meters are long) of Korea S, this bridge is provided with 113 nodes (except base station and
Gateway node), wherein 105 nodes use battery to power, and extra 8 nodes use solar energy charging battery to power.These pass
Sense node is used for measuring bridge acceleration, strain, humiture and wind speed.The cost of each sensor is 500 dollars.In this system
Main two aspects that are limited to: 1) call duration time.Due to meshed network conflict, obtaining data from 46 sensor nodes needs near
30 minutes.2) battery life.Node equipment has Large Copacity 20,000mAh battery.If node only gathers data 4 times every day, battery
Capacity will reduce after two months to 75%.The potential cause of battery capacity development observes Eveready law.Compared to micro-place
Reason machine technology, the development of battery capacity is slowly.Current industrial battery exemplary energy density is 150-200Wh/kg,
1000 cycle charging number of times.This means that any passive system being equipped with rechargeable battery will undertake high maintenance funds
(generally speaking needing every some months to safeguard once).Further, since sensing and the high power consumption demand communicated, completely passive energy is adopted
Collection solution does not has feasibility.
The error that the error temperature that temperature causes causes perhaps is not by structure health monitoring as hiding parameter
System manufacturer is open.Owing to the overall volume of structure is proportionate with temperature, the change of temperature will cause obvious error.
Its reason has multiple, the most typically has two classes: temperature affects sensor (such as foil gauge) itself;Temperature affects sample devices
(such as digital to analog converter).The error degree that temperature causes usually reaches six times of the normal strain applied by load.In order to solve
Such problem, existing system uses temperature correction doing metrophia compensation.But fact proved even with temperature correction,
Strain measurement error rate still remains high, and its error amount ordinary wave moves between hundreds of micron to millimeter.
Another important aspect is when system is installed, repairs, safeguarded or the calibration operation of escalation process system.Although
This is not the problem on funds, but these system diagnostics and operation are required for technical professional and just can carry out, otherwise
The optimum state of system can not get ensureing.
Seeing on practical conditions, Radio frequency interference and electromagnetic interference are the another kind of factors affecting working state of system.Lift
Individual example, if monitoring system built by power main and GSM signal tower, system will be serious by these noise sources
Impact.Generally, monitoring system duty under such circumstances can not get any guarantee.By contrast, based on light
Fine system has more preferable reliability, and system based on ADC can be greatly affected.
Summary of the invention
For above-mentioned prior art, present invention aim at providing the sensor assembly for structure health detection, solve
Certainly used in prior art, sensor has not been able to realize completely passive, poor anti jamming capability and the technical problem such as with high costs.
For reaching above-mentioned purpose, the technical solution used in the present invention is as follows:
For the sensor assembly of structure health detection, including control signal and radiofrequency signal, also include energy acquisition
Module, for energy absorption, coupling receives radiofrequency signal and changes into DC voltage;Energy management module, for as driving
Power supply, receives the voltage signal of energy acquisition module output and stores these voltages and voltage stabilizing output;Former based on radar
The sensing module of reason, receives the DC voltage of energy management module output, also receives control signal;Sensor group, is used for gathering
The STRESS VARIATION information of structure;Wherein, described sensing module is selectively exported radar pulse signal to institute by control signal
The sensor group stated, and receive the STRESS VARIATION transducing signal of described sensor group output;Wherein, described sensing module is the most defeated
Go out to have the feedback signal of STRESS VARIATION information.
In such scheme, described energy acquisition module, including microstrip antenna, for energy absorption, coupling receives radio frequency
Signal;Radio frequency-direct current transducer, the radiofrequency signal of conversion microstrip antenna coupling output is to voltage signal;Electric charge pump, lifting is penetrated
The magnitude of voltage of frequently-direct current transducer output voltage signal.
In such scheme, described energy management module, including storage electric capacity, receive the voltage of energy acquisition module output
Signal;Power manager, detection storage capacitance voltage value;Boost chopper, the unidirectional current of stable storage electric capacity release output
Pressure.
In such scheme, described sensing module, including main control module, it is used for control being provided, communicating and process;Radar arteries and veins
Rushing generator, be used for providing sensor group signal source, the control receiving main control module output drives signal;Radar pulse storage electricity
Hold, receive and store the radar pulse signal of radar pulse generator output;On-off circuit, receives the selection of main control module output
The radar pulse signal of signal selectively release radar pulse storage electric capacity is to sensor group;Timing module, is used for measuring thunder
Reach pulse time-of-flight, receive the stress sensing signal of sensor group output;High frequency clock crystal oscillator, is used for providing sampled reference,
Output high frequency time base clock is to timing module;System clock crystal oscillator, is used for providing working standard, output services reference clock
To main control module;Communication module, receives control signal and sends to main control module or the feedback signal of transmission main control module.
In such scheme, described sensor group, select passive sensor group, passive sensor group passes including temperature
Sensor and strain gauge, gather the temperature information of structure and gather the STRESS VARIATION letter echoed through structure passively
Breath;
In such scheme, described sensing module, also include temperature compensation module, temperature compensation module receives main control module
Output simple radar pulse signal and its also export compensated pulse signal to timing module.
Compared with prior art, beneficial effects of the present invention:
(1) completely passive structure detection sensor assembly is achieved;
(2) sensor module structure is possible not only to communication and can also receive sensor group collection data;
(3) achieve and there is the energy acquisition module of microstrip antenna, for sensor energy supply;
(4) in terms of counter stress data acquisition, prior art uses traditional method (ADC+ Wheatstone bridge), and uses thunder
Reach measurement resistance value (stress and temperature) method;Two kinds of Method And Principle differences, the former is for measuring voltage, and the latter is the measurement time,
The interference of the latter's anti-data, degree of accuracy height and calculating speed are fast;
(5) passive sensor module obtains energy from wireless radiofrequency electric wave, owing to radiofrequency signal is to be read by human hand held formula
Read device to send, therefore its frequency and energy are it is believed that have more preferable range of application and prospect.
Accompanying drawing explanation
Fig. 1 is sensor of the invention module diagram;
Fig. 2 is the energy module schematic diagram of the present invention;
Fig. 3 is the sensing module schematic diagram of the present invention;
Fig. 4 is the temperature compensation module schematic diagram of the present invention.
Detailed description of the invention
All features disclosed in this specification, or disclosed all methods or during step, except mutually exclusive
Feature and/or step beyond, all can combine by any way.
The present invention will be further described below in conjunction with the accompanying drawings:
Embodiment 1
Such as Fig. 1, the parameter of described sensor group, it is 1,000 5000 μ ε that foil gauge measures scope, and foil gauge precision is 10 μ
ε, temperature measurement range is-40 to+125 DEG C, and temperature accuracy is ± 0.5 DEG C ± 0.3 DEG C (to be measured every time and will sample 250 in sheet
Secondary average), moisture measurement scope is 0-100%RH, and humidity precision is Δ ε < 100 μm (-20 for ± 3%RH temperature drift
To+100 DEG C), calibration is without (need not), and rate of false alarm is 0% (in 250 sheets, sampling avoids system wrong report), by radio frequency/electromagnetism
Affect nothing.
As in figure 2 it is shown, also can be absorbed by the microstrip antenna of energy acquisition module when radiofrequency signal arrives equipment simultaneously.Micro-
Band antenna has more preferable energy absorption capability compared to dipole antenna (using in communication and control module), but the most anti-
Poor to scatter communication ability, therefore use the energy acquisition module of microstrip antenna to be only used for as high power consumption sensor and provide extra
Sufficient power supply.Radiofrequency signal is converted into DC voltage, so through microstrip antenna by the energy acquisition module of RF-DC converter inside
Boosted by electric charge pump afterwards and fill and can store electric capacity.Voltage in power manager monitoring storage electric capacity.When capacitance energy storage abundance,
Power manager informs MCU (microcontroller) or the state of processor energy acquisition module by INT pin.If additionally, storage
Electric capacity have selected super capacitor according to application, can put RESET pin handover module by peripheral circuit and fill and can pattern reduce super
The time to recharge of level electric capacity.When store electric capacity fill can enough time, electric capacity electric discharge flows to boost chopper.Boost chopper will
Exporting after the boost in voltage voltage stabilizing of electric capacity at Vout pin is sensor power.The voltage of Vout is customizable,
Controlled by VSET pin input voltage.
As it is shown on figure 3, this module is for structure health monitoring.Whole module is controlled by governor circuit.Radar surveying
Core be made up of radar pulse generator, pulse storage electric capacity, on-off circuit, passive sensor group and timing module.Master control
Control radar pulse generator produces pulse, and the pulse of generation is stored among pulse storage electric capacity.Pulse foot when accumulation
Time enough, master control controls on-off circuit release pulses.The pulse signal of release carries the information of sensor after passing through sensor,
And measured by high-precision timing module.After obtaining sensor information, sensor information is sent to master control by timing module.Mould
Block uses two clock crystal oscillators.Wherein system clock crystal oscillator provides work tempo for master control, and independent high frequency clock crystal oscillator is
Timing module provides measures beat.Additionally, communication module is responsible for communicating with external circuit (such as MCU, processor etc.), number will be measured
According to uploading or receiving control command.
Variations in temperature is caused to the error of sensor measurement, it is possible to use temperature-compensating reduces.As shown in Figure 4, temperature
Thermo-sensitive resistor, High-precision standard resistance and amplifier is had inside degree compensating module.The resistance value of thermo-sensitive resistor can along with temperature in
Existing linear change, and High-precision standard resistance temperature influence is minimum.Process and sensor measurement process class are measured in temperature-compensating
Seemingly.Unlike sensor measurement process: temperature-compensating is to be produced simple radar pulse by governor circuit is internal, and this pulse divides
After thermo-sensitive resistor and measuring resistance, after amplifier amplifies, do not become compensated pulse signal, timing module measure, and will
Measurement result is sent to master control.Master control afterwards is through being calculated temperature ratio, as the foundation of temperature-compensating.
The above, the only detailed description of the invention of the present invention, but protection scope of the present invention is not limited thereto, and any
Belong to those skilled in the art in the technical scope that the invention discloses, the change that can readily occur in or replacement, all answer
Contain within protection scope of the present invention.