CN204390385U - Based on the well lid motion state monitoring device of Gravity accelerometer - Google Patents

Abstract

The utility model discloses a kind of well lid motion state monitoring device based on Gravity accelerometer, monitoring device comprises main control module, and described main control module is connected with the Gravity accelerometer be arranged on well lid, GPS module; Described main control module and GPRS/WIFI module are bi-directionally connected; Described GPRS/WIFI module communicates with monitor terminal.The utility model introduces Gravity accelerometer first in well lid monitoring, accurately can judge the state of well lid, and alarm, substantially increases validity and the accuracy of well lid supervisory system, also strengthens the stability of whole well lid supervisory system thus.

Description

Based on the well lid motion state monitoring device of Gravity accelerometer

Technical field

The utility model relates to a kind of well lid motion state monitoring device based on Gravity accelerometer.

Background technology

Manhole, once run into damaged or stolen, if can not get timely process, has vehicles or pedestrians and occurs accident because of ignorant, and potential safety hazard is very large, therefore, accomplishes to judge accurately just to seem particularly important to the disappearance of well lid or damage.Occur if having breakage or lose, generally that pedestrian directly finds also and alarm, this kind obviously lacks controllability by conscious mode entirely, fundamentally can not reach the requirement of Realtime Alerts, so design, a kind of device that automatically can identify well lid state can effectively solution must not the drawback of Timeliness coverage, carries out real-time analysis, can judge the current state of well lid accurately by the change of Gravity accelerometer to the acceleration of well lid and inclination angle, accomplish Timeliness coverage, and alarm.

Gravity sensor carrys out work according to the principle of piezoelectric effect.So-called piezoelectric effect is exactly " be added in external force on crystal except making crystal generation deformation for the heteropolar crystal that there is not symcenter; also will change the polarized state of crystal; set up electric field at crystals, this phenomenon making medium that polarization occur due to mechanical force is called direct piezo electric effect ".Gravity sensor is exactly this characteristic of crystal modification caused due to acceleration that make use of its inside.Because this distortion can produce voltage, as long as calculate the relation produced between voltage and the acceleration applied, just voltage output can be changed into by degree of will speed up.Certainly, other method a lot of is also had to make Gravity accelerometer, such as capacity effect, thermal effect, luminous effect, but its most basic principle is all produce distortion because acceleration produces certain medium, exports by measuring its deflection and changing into voltage with interlock circuit.

Summary of the invention

Technical problem to be solved in the utility model is, for above-mentioned the deficiencies in the prior art, provides a kind of well lid motion state monitoring device based on Gravity accelerometer.

For solving the problems of the technologies described above, the technical scheme that the utility model adopts is: a kind of well lid motion state monitoring device based on Gravity accelerometer, and comprise main control module, described main control module is connected with the Gravity accelerometer be arranged on well lid; Described main control module and GPRS/WIFI module are bi-directionally connected; Described GPRS/WIFI module communicates with monitor terminal.

Described main control module is connected with GPS module, and GPS module can locate the particular location of well lid.

Described main control module is connected with watchdog circuit, real time clock circuit.

The utility model additionally provides a kind of method utilizing above-mentioned monitoring device to monitor well lid motion state, comprises the following steps:

1) Gravity accelerometer judges whether well lid is in free falling body state, if so, then enters 5); Otherwise, enter 2);

2) whether the acceleration of gravity of master control module judges well lid is greater than threshold value a, if so, enters 3); Otherwise, return 1); Wherein, a=1.5g ~ 2.5g;

3) whether the change in gravitational acceleration cycle of master control module judges well lid is greater than threshold value t, if so, enters 4); Otherwise, return 1); Wherein, t=300ms ~ 600ms;

4) whether the change at master control module judges well lid inclination angle is greater than threshold value w, if so, then judge well lid damage or stolen, monitor terminal start alert program; Otherwise, return 1); Wherein, w=60 ~ 90 degree.

Compared with prior art, the beneficial effect that the utility model has is: the utility model introduces Gravity accelerometer first in well lid monitoring, pass through Gravity accelerometer, for accurately judging that the state of well lid provides hardware implementing basis, thus validity and the accuracy of well lid supervisory system can be improved.

Accompanying drawing explanation

Fig. 1 is the utility model one embodiment supervising device schematic diagram;

Fig. 2 is utility model works process flow diagram;

Fig. 3 is the constitutional diagram of the utility model variables A reflection well lid shake;

The change curve of A when Fig. 4 is the irregular movement of the utility model well lid;

The change curve at inclination angle when Fig. 5 is the irregular movement of the utility model well lid.

Embodiment

As shown in Figure 1, the utility model one embodiment comprises main control module, and described main control module is connected with the Gravity accelerometer be arranged on well lid, GPS module; Described main control module and GPRS/WIFI module are bi-directionally connected; Described GPRS/WIFI module communicates with monitor terminal.

Gravity accelerometer model of the present utility model is ADXL345, ADXL345 is a little and thin super low-power consumption 3 axis accelerometer, and resolution high (13), measurement range reaches ± 16g.ADXL345 is applicable to mobile device application very much.It can measure static weight acceleration in tilt detection application, can also measure motion or impact the dynamic acceleration caused.Its high resolving power (3.9mg/LSB), can measure the angle change less than 1.0 °.This device provides multiple special detection function.Movable and inactive measuring ability is detected by the threshold value comparing acceleration on arbitrary axis and user and arrange and occurs with or without moving.Knock measuring ability and can detect singly shaking of any direction and two vibration work.Whether freely falling body measuring ability can detection means drop.These functions independently can be mapped to one in two interrupt output pins.The integrated memory management system applied for a patent adopts one 32 grades first in first out (FIFO) impact dampers, can be used for storing data, thus is down to minimum by host-processor load, and reduces total system power consumption.Low-power consumption mode supports based drive intelligent electric power management, thus carries out threshold value sensing and acceleration of motion measurement with extremely low power consumption.

GPRS/WIFI communication function, monitor terminal is wanted in time the state of well lid to be uploaded to Surveillance center by GRPS, and when especially there is stolen or movement, ensure to report to the police to Surveillance center in the very first time, Here it is claims to communication actual effect.Consider for economize on electricity, the mode of operation of ' ticking formula ' is taked in the work of GPRS communication part, and namely when not there is well lid track exception, system started a communication every 4 hours, and sent state to monitor terminal.Receive after monitor terminal is replied and again enter dormancy, wait for waking up next time.Abnormal if there is well lid track, system can start GPRS/WIFI communication in real time, and always to monitor terminal report condition, until remove.

GPS positioning function, this function is system optional function, by reading GPS locating information, Surveillance center can be allowed to obtain the accurate location of well lid and make accurate identification in map, maintain easily.

In order to ensure the work of system long time stability, system introduces watchdog circuit, and its effect prevents program from entering endless loop, the normal operation of watchdog routine.After program normally performs one time, can reset house dog counter, so can not arrive maximum count value, but if program enters endless loop due to reasons such as external disturbance, watchdog circuit can make system reset by force.

The state of well lid has:

A: static (normality)

B: shake (oversize vehicle crosses and causes road shock or have vehicle to roll from well lid and cross)

C: freely falling body (well lid break after back drop under)

D: violent irregular movement (by people be move maintenance or steal)

As can be seen from state above, the normal state of well lid is static and shake, and the state when meeting accident is for falling or violent irregular movement.These states are also the foundations of the utility model method.

Because well lid individual difference is very little, the change classification of their state is also relatively single, as long as so carry out analysis by change two parameters at acceleration of gravity and inclination angle just can reach system requirements, in conjunction with the actual state of well lid, the utility model proposes the threshold calculation based on acceleration of gravity and inclination angle.

First by the state acceleration of well lid aand inclination angle θset up mathematical expression.

A: acceleration time static aand inclination angle θoutput be all zero, it should be noted that this three axis accelerometer each axle under static state exports in addition is not 0 entirely.Under static state, oppositely, then the output of this axle is 1g for the direction of which axle of X, Y, Z and acceleration of gravity direction, and it is 0 that other diaxons export; With acceleration of gravity in the same way, then the output of this axle is-1g, other diaxons export be 0.In sum, under stationary state a and θexpression formula be:

a = ax+ay+az = 1g

θ = 0°

B: shake, when oversize vehicle cross cause road shock or have vehicle from well lid roll and cross time, well lid can with landing ground vibrations produce shake, the feature of this shake is that amplitude is little, and speed is fast, and the duration is short, as long as the change of acceleration, inclination angle changes hardly.

Here we set the size that a variables A is used for representing resultant acceleration vector, namely

；

Wherein ax, ay, az are X, the data of Y, Z tri-axles, A is the amplitude of the resultant acceleration vector of three axles, its size is relevant with the severe degree of well lid velocity variations, and has nothing to do with the direction of motion, and this also meets well lid track and judges that only concern amplitude ignores the feature in direction.

Shake is represented with A, can be regarded as acceleration and do swing back and forth at an initial point, as shown in Figure 3.

Come as seen from Figure 3, when well lid receive roll time, in very short time, the change of acceleration is intensive, all concentrates near initial point simultaneously and swings up and down.Now inclination angle theta is constant.

C: freely falling body, if well lid falls, free falling body state will be formed, whether ADXL345 itself has freely falling body measuring ability, can detection means drop, if freely falling body occurs, the configured port meeting set of ADXL345, notification processor, very convenient and practical, software process is also very simple.

D: violent irregular movement, this motion illustrates that well lid is pulled open, and has a lasting motion, shows on acceleration be exactly lasting significantly change, and irregular, and now the change at inclination angle is also larger.Fig. 4 and Fig. 5 embodies the Variation Features of acceleration amplitude A and inclination angle theta in irregular movement respectively.

It is exactly more than the mathematical expression of well lid 4 kinds of states, the change of the acceleration corresponding to often kind of state and change of pitch angle can be found still obviously, utilize the threshold calculation of acceleration of gravity and inclination angle to judge that whether well lid is stolen or damage so we have proposed.Meanwhile, we, in order to better distinguish the speed difference of shake and the change of irregular movement brief acceleration, introduce time threshold values.So far, overall method flow as shown in Figure 2.

Claims (3)

1., based on a well lid motion state monitoring device for Gravity accelerometer, it is characterized in that, comprise main control module, described main control module is connected with the Gravity accelerometer be arranged on well lid; Described main control module and GPRS/WIFI module are bi-directionally connected; Described GPRS/WIFI module communicates with monitor terminal.

2. the well lid motion state monitoring device based on Gravity accelerometer according to claim 1, it is characterized in that, described main control module is connected with GPS module.

3. the well lid motion state monitoring device based on Gravity accelerometer according to claim 2, it is characterized in that, described main control module is connected with watchdog circuit, real time clock circuit.