阅读说明：本技术 自供能的高速公路交通和路基模量监测系统及监测方法 (Self-powered highway traffic and roadbed modulus monitoring system and monitoring method ) 是由 曹志刚 马力 蔡袁强 于 2019-10-14 设计创作，主要内容包括：本发明提供一种自供能的高速公路交通和路基模量监测系统及监测方法,该系统包括压电传感器、称重装置、附属单元及计算机终端。本发明将压电传感器和称重装置沿高速公路埋设在高速公路路基中,附属单元布置在高速公路旁,采用称重装置监测汽车重量,压电传感器监测汽车速度,最后通过汽车重量、速度和压电传感器的电压峰值反算路基模量,实现检测高速公路路基模量的目的。压电传感器具有力电耦合特性,可以同时把收集到的振动能量存入储能电容,该储能电容可以为称重装置以及其他部件供电。本发明利用高速公路上汽车产生的振动,可以同时自供能监测汽车重量、速度和路基模量,为高速公路提供安全预警,推进高速公路物联网建设。(The invention provides a self-powered monitoring system and a monitoring method for highway traffic and roadbed modulus. The invention buries the piezoelectric sensor and the weighing device in the highway subgrade along the highway, the accessory units are arranged beside the highway, the weighing device is adopted to monitor the weight of the automobile, the piezoelectric sensor is used to monitor the speed of the automobile, and finally the subgrade modulus is inversely calculated through the weight and the speed of the automobile and the voltage peak value of the piezoelectric sensor, thereby realizing the purpose of detecting the subgrade modulus of the highway. The piezoelectric sensor has the characteristic of force-electricity coupling, and can store collected vibration energy into an energy storage capacitor, and the energy storage capacitor can supply power to the weighing device and other components. The invention can monitor the weight, speed and roadbed modulus of the automobile by self-energy supply by utilizing the vibration generated by the automobile on the highway, provides safety early warning for the highway and promotes the construction of the internet of things of the highway.)

1. A self-powered monitoring system for highway traffic and roadbed modulus is characterized by comprising a piezoelectric sensor, a vehicle weighing device for measuring the weight of a passing vehicle, a vehicle speed measuring device for measuring the speed of the passing vehicle, an accessory unit and a computer terminal;

the piezoelectric sensors are arranged in a roadbed below a pavement layer along the highway and used for acquiring vibration of the roadbed when vehicles pass through the roadbed and generating electric signals;

the auxiliary unit is arranged on one side of the highway and specifically comprises an energy storage unit, an analysis unit, a GPS (global positioning system) and a wireless transmission unit.

The energy storage unit is used for storing surplus electric energy and supplying energy to other components in the auxiliary unit;

the analysis unit obtains the speed and the weight of a passing vehicle obtained by the vehicle weighing device and the vehicle speed measuring device in real time, and reversely calculates the output voltage peak value of the parallel piezoelectric sensor to obtain the real-time roadbed modulus E, wherein the reverse calculation formula is as follows:

in the above formula, V is the output voltage peak of the piezoelectric sensor, q is the vehicle axle load, V is the vehicle speed, E is the roadbed modulus, Ψ is the parameter of the piezoelectric material in the piezoelectric sensor,

And finally, transmitting the obtained real-time roadbed modulus E, the speed and the weight of the passing vehicle to a computer terminal of a highway management department through a wireless transmission unit to realize real-time monitoring.

And the GPS is used for positioning the position of the current roadbed modulus monitoring system.

2. The monitoring system of claim 1, further comprising an elastomeric encapsulating housing for encapsulating the piezoelectric sensor.

3. The monitoring system of claim 1, wherein the piezoelectric sensor is a stacked nano zinc oxide piezoelectric sensor.

4. The monitoring system of claim 1, wherein the vehicle weighing device is a membrane soil pressure pad.

5. The monitoring system according to claim 1, wherein the vehicle speed measuring device is directly composed of two piezoelectric sensors arranged along the road direction, the distance between the two sensors is L, and the peak time difference of the waveforms of the electric signals generated by the two sensors is (t)₂-t₁) Then the speed can be based on

6. A monitoring method based on the self-powered high-speed traffic and roadbed modulus monitoring system of claim 1, which is characterized by comprising the following steps:

(1) arranging a monitoring system along the highway, wherein the piezoelectric sensor is arranged in the roadbed with the depth of about 20cm, and the vehicle weighing device and the vehicle speed measuring device are arranged near the piezoelectric sensor according to a test principle; the attachment unit is arranged beside the expressway.

(2) When the vehicle passes through the monitoring system, vibration is generated in the roadbed, the piezoelectric sensor collects vibration energy and outputs an electric signal to the analysis unit, and the residual energy is stored in the energy storage unit to supply energy to other components. Meanwhile, the vehicle weighing device and the vehicle speed measuring device respectively obtain the weight and the speed of the passing vehicle and transmit the weight and the speed to the analysis unit;

(3) the analysis unit inversely calculates the roadbed modulus through the obtained weight and speed of the passing vehicle and the voltage peak value of the electric signal of the piezoelectric sensor, and transmits the obtained real-time roadbed modulus E, the speed and the weight of the passing vehicle to the computer terminal through the wireless transmission unit to realize real-time monitoring.

(4) When the monitored subgrade modulus E is attenuated by more than 30%, workers can go to the position located by the GPS positioning system to perform subgrade maintenance. When the monitored speed and weight of the set vehicle exceed the overspeed value v of the expressway_mOverload value M_mIndicating that the passing vehicle is over-speed or over-loaded.

Technical Field

The invention relates to the field of highway traffic and roadbed modulus monitoring, in particular to a self-powered sensor for monitoring highway speed, vehicle weight and roadbed modulus by utilizing a piezoelectric technology.

Background

Under the cyclic loading of the vehicle, the roadbed modulus can be slightly attenuated. The roadbed modulus is an important index for showing whether the roadbed is in a healthy and stable state, so that the roadbed modulus on the expressway is monitored in real time, and the roadbed modulus monitoring method has important significance. The traditional roadbed modulus detection method needs to destroy a roadbed main body and cannot monitor a roadbed in real time.

Secondly, since long ago, the invention patent CN207268904U and the invention patent CN107742424A have made sensors by piezoelectric materials to monitor traffic, but the piezoelectric sensors can be used not only to monitor traffic flow, but also to monitor surrounding environmental indicators, such as roadbed modulus, which can reflect roadbed status.

Meanwhile, the invention patent CN201710444838 discloses an expressway subgrade monitor, which is characterized in that a subgrade monitoring probe is embedded into an expressway subgrade to monitor the change of pressure in the subgrade, so as to judge whether the subgrade collapses. However, the device needs power supply equipment, the load of the expressway is complex, and a plurality of factors can cause the change of the pressure in the roadbed, so that the method for judging whether the roadbed collapses or not by monitoring the change of the pressure in the roadbed is not accurate.

Therefore, the piezoelectric material and the film type soil pressure piece are simultaneously embedded under the highway, vibration generated in a roadbed after an automobile passes through is converted into an electric signal based on the force-electricity coupling characteristic of the piezoelectric material, the weight of the automobile is obtained through the film type soil pressure piece, the speed of the automobile is obtained through analyzing the piezoelectric signal, and finally, the voltage peak value of the piezoelectric signal and the speed and weight of the automobile are combined, so that the modulus of the roadbed can be inversely calculated, and the aim of monitoring the modulus of the roadbed in real time is fulfilled.

Disclosure of Invention

The invention aims to solve the problems and provides a self-powered highway traffic and roadbed modulus monitoring system and a monitoring method. Meanwhile, vibration generated by the running of the automobile can be converted into electric energy by the piezoelectric sensor, and the electric energy is stored by the energy storage capacitor and then is used for supplying power to other parts, so that the self-powered monitoring of the system is realized.

The technical scheme adopted by the invention is as follows:

a self-powered monitoring system for highway traffic and roadbed modulus comprises a piezoelectric sensor, a vehicle weighing device for measuring the weight of a passing vehicle, a vehicle speed measuring device for measuring the speed of the passing vehicle, an accessory unit and a computer terminal;

the piezoelectric sensors are arranged in a roadbed below a pavement layer along the highway and used for acquiring vibration of the roadbed when vehicles pass through the roadbed and generating electric signals;

the auxiliary unit is arranged on one side of the highway and specifically comprises an energy storage unit, an analysis unit, a GPS (global positioning system) and a wireless transmission unit.

The energy storage unit is used for storing surplus electric energy and supplying energy to other components in the auxiliary unit; the energy storage capacitor comprises a super capacitor bank, a bidirectional DC/DC converter and a corresponding control circuit. The energy storage capacitor can store the electric signal generated by the piezoelectric sensor and generate stable voltage and current to supply energy to other components;

the analysis unit obtains the speed and the weight of a passing vehicle obtained by the vehicle weighing device and the vehicle speed measuring device in real time, and reversely calculates the output voltage peak value of the parallel piezoelectric sensor to obtain the real-time roadbed modulus E, wherein the reverse calculation formula is as follows:

in the above formula, V is the output voltage peak of the piezoelectric sensor, q is the vehicle axle load, V is the vehicle speed, E is the roadbed modulus, Ψ is the parameter of the piezoelectric material in the piezoelectric sensor,

R_Lis an external resistor, d₃₃Is the piezoelectric constant of the piezoelectric material, i is an imaginary unit, S is the area of the piezoelectric material, C_pIs equivalent capacitance of piezoelectric material, omega is frequency, D_pAnd xi and eta are parameters of x and y after Fourier transformation, wherein the bending rigidity of the pavement is obtained.

And finally, transmitting the obtained real-time roadbed modulus E, the speed and the weight of the passing vehicle to a computer terminal of a highway management department through a wireless transmission unit to realize real-time monitoring.

And the GPS is used for positioning the position of the current roadbed modulus monitoring system.

Further, the piezoelectric sensor further comprises an elastic rubber packaging shell used for packaging the piezoelectric sensor, and the elastic rubber packaging shell is in good contact with soil.

Furthermore, the piezoelectric sensor is a stacked nano zinc oxide piezoelectric sensor.

Further, the vehicle weighing device is a film type soil pressure sheet.

Further, the vehicle speed measuring device directly comprises two piezoelectric sensors arranged along the road direction, and the principle is as follows: FIG. 7 shows waveforms of two piezoelectric sensors with a distance L when the same vehicle passes, and the time interval of the peak is (t)₂-t₁)。

It can be seen that the peak voltages of the two waveforms correspond to time t₁And t₂The corresponding time is the time when the vehicle reaches two piezoelectric sensors at a distance L, so the vehicle speed v can be determined according to the following equation:

the invention also provides a monitoring method of the self-powered high-speed traffic and roadbed modulus monitoring system, which comprises the following steps:

(1) arranging a monitoring system along the highway, wherein the piezoelectric sensor is arranged in the roadbed with the depth of about 20cm, and the vehicle weighing device and the vehicle speed measuring device are arranged near the piezoelectric sensor according to a test principle; the attachment unit is arranged beside the expressway.

(2) When the vehicle passes through the monitoring system, vibration is generated in the roadbed, the piezoelectric sensor collects vibration energy and outputs an electric signal to the analysis unit, and the residual energy is stored in the energy storage unit to supply energy to other components. Meanwhile, the vehicle weighing device and the vehicle speed measuring device respectively obtain the weight and the speed of the passing vehicle and transmit the weight and the speed to the analysis unit;

(3) the analysis unit inversely calculates the roadbed modulus through the obtained weight and speed of the passing vehicle and the voltage peak value of the electric signal of the piezoelectric sensor, and transmits the obtained real-time roadbed modulus E, the speed and the weight of the passing vehicle to the computer terminal through the wireless transmission unit to realize real-time monitoring.

(4) When the monitored subgrade modulus E is attenuated by more than 30%, workers can go to the position located by the GPS positioning system to perform subgrade maintenance. When the monitored speed and weight of the set vehicle exceed the overspeed value v of the expressway_mOverload value M_mIndicating that the passing vehicle is over-speed or over-loaded.

The invention has the beneficial effects that:

1. the invention integrates the highway speed measurement, the weight measurement and the monitored road base modulus, so that the highway detection system is more comprehensive and more convenient.

2. The monitoring system can stably monitor the modulus of the highway subgrade for a long time without drilling and damaging. The monitoring system can provide early warning for highway subgrade monitoring and accelerate traffic Internet of things construction.

3. The invention adopts the self-powered sensor, solves the problem of long-distance cable transmission and also solves the problem of complex wire arrangement.

4. The invention combines a GPS positioning system to position and maintain the roadbed modulus attenuation area.

Description of the drawings:

FIG. 1 is a schematic structural diagram of a highway traffic and roadbed modulus monitoring system, wherein a is a vertical section view of the monitoring system and b is a top view of the monitoring system;

FIG. 2 is a schematic diagram of a piezoelectric sensor configuration;

FIG. 3 is a schematic diagram of the logic of the analysis unit;

figure 4 piezoelectric sensor signal outputs at different subgrade moduli;

FIG. 5 is a plot of peak voltage calibration subgrade modulus (different axle loads);

FIG. 6 is a plot of peak voltage calibration subgrade modulus (at different speeds);

FIG. 7 is a waveform diagram of two piezoelectric sensors at a distance L;

in the figure, 1: an asphalt pavement; 2: a film type soil pressure sheet; 3: a piezoelectric sensor; 4: a roadbed; 5: an automobile; 6: piezoelectric sensors and membrane soil pressure pads (overlook); 7: stacking nano zinc oxide (5); 8: a wire; 9: a high-elasticity rubber packaging shell.

Detailed Description

To explain the rationality of the present monitoring system, the following theoretical verification is made:

theoretical verification is established on the basis of the Biot fluctuation theory:

σ_ij＝λδ_ijθ+μ(u_i,j+u_j,i)-αδ_ijp_f

in the formula u_i(i ═ x, y, z) are displacements of the soil skeleton in the x, y, z directions, respectively; w is a_i(i ═ x, y, z) displacement of the liquid phase relative to the soil skeleton in the x, y, z directions; alpha and M are saturated soil body parameters representing compressibility of soil particles and pore fluid; rho, rho_fDensity of soil and liquid phase respectively; where is rho_fThe/n is a parameter reflecting the porosity of the soil body; n is the porosity of the soil body; b is a physical quantity reflecting the internal friction force during fluid-solid relative displacement, u_i、w_iThe upper points represent the derivative with respect to time t; λ and μ are L-me constants. Theta ═ u_i,iStrain of soil body; sigma_ijThe total stress of the soil body; p is a radical of_fPore water pressure; delta_ijIs a DiracDelta function.

The weight q of the vehicle moved simultaneously by the above formula can be used to calculate the stress in the foundation as:

in the formula sigma_zIs vertical stress, q is the vehicle axle load, D_pIs the flexural rigidity m of the asphalt pavement_bFor the quality of the asphalt pavement, E is the modulus of the roadbed, omega is the frequency, and xi and eta are parameters for transforming x and y into a wave number domain.

And substituting the piezoelectric equation of the piezoelectric sensor:

D＝d₃₃σ_z(x,y,z,t)+ε₃₃E_z(x,y,z,t)

wherein D is the potential shift, D₃₃Is the piezoelectric constant,. epsilon₃₃Ez is the electric field strength.

Finally, the output voltage of the piezoelectric sensor is obtained as follows:

wherein V is voltage, psi is piezoelectric sheet parameter,

R_Lis an external resistor, d₃₃Is the piezoelectric constant of the piezoelectric material, i is an imaginary unit, S is the area of the piezoelectric material, C_pIs the piezoelectric equivalent capacitance and ω is the frequency.

The final output voltage obtained by integration is:

finally, the output voltage is related to the roadbed modulus E, the automobile weight q is related to the automobile speed v, the automobile moving speed v can be calculated according to the waveform, the automobile weight q can be measured according to the thin film type soil pressure sheet, and the roadbed modulus E can be inversely calculated by combining the voltage peak values q and v of the piezoelectric sensor.

Fig. 4 is a waveform diagram of the output electrical signals of the normal roadbed and the modulus attenuation roadbed, and if the roadbed modulus is attenuated, the voltage peak value is increased, which illustrates that the signal analysis unit can judge the attenuation condition of the roadbed modulus according to the voltage peak value.

Fig. 5 is a graph for calibrating different roadbed shear moduli through voltage peaks under different vehicle axle loads, and if the voltage peaks change, the corresponding roadbed shear moduli start to change, which shows that the roadbed condition can be judged according to the change.

Fig. 6 is a graph for calibrating different roadbed shear moduli through voltage peaks at different automobile speeds, and if the voltage peaks change, the corresponding roadbed shear moduli start to change, which shows that the roadbed condition can be judged according to the change. Further demonstrating the feasibility of this principle.

FIG. 1 is a self-powered highway traffic and subgrade modulus monitoring system in accordance with the principles of the present invention, including a piezoelectric sensor, a vehicle weighing device for measuring the weight of a passing vehicle, a vehicle speed measuring device for measuring the speed of the passing vehicle, an accessory unit and a computer terminal;

the piezoelectric sensors are arranged in a roadbed below a pavement layer along the highway and used for acquiring vibration of the roadbed when vehicles pass through the roadbed and generating electric signals;

the auxiliary unit is arranged on one side of the highway and specifically comprises an energy storage unit, an analysis unit, a GPS (global positioning system) and a wireless transmission unit.

The energy storage unit is used for storing surplus electric energy and supplying energy to other components in the auxiliary unit;

the analysis unit obtains the speed and the weight of a passing vehicle obtained by the vehicle weighing device and the vehicle speed measuring device in real time, and reversely calculates the output voltage peak value of the parallel piezoelectric sensor to obtain the real-time roadbed modulus E, wherein the reverse calculation formula is as follows:

in the above formula, V is the output voltage peak of the piezoelectric sensor, q is the vehicle axle load, V is the vehicle speed, E is the roadbed modulus, Ψ is the parameter of the piezoelectric material in the piezoelectric sensor,

R_Lis an external resistor, d₃₃Is the piezoelectric constant of the piezoelectric material, i is an imaginary unit, S is the area of the piezoelectric material, C_pIs equivalent capacitance of piezoelectric material, omega is frequency, D_pAnd xi and eta are parameters of x and y after Fourier transformation, wherein the bending rigidity of the pavement is obtained.

And finally, transmitting the obtained real-time roadbed modulus E, the speed and the weight of the passing vehicle to a computer terminal of a highway management department through a wireless transmission unit to realize real-time monitoring.

And the GPS is used for positioning the position of the current roadbed modulus monitoring system.

The monitoring method of the self-powered highway traffic and roadbed modulus monitoring system comprises the following steps:

(1) arranging a monitoring system along the highway, wherein the piezoelectric sensor is arranged in the roadbed with the depth of about 20cm, and the vehicle weighing device and the vehicle speed measuring device are arranged near the piezoelectric sensor according to a test principle; the attachment unit is arranged beside the expressway.

(2) When the vehicle passes through the monitoring system, vibration is generated in the roadbed, the piezoelectric sensor collects vibration energy and outputs an electric signal to the analysis unit, and the residual energy is stored in the energy storage unit to supply energy to other components. Meanwhile, the vehicle weighing device and the vehicle speed measuring device respectively obtain the weight and the speed of the passing vehicle and transmit the weight and the speed to the analysis unit;

(3) the analysis unit inversely calculates the roadbed modulus through the obtained weight and speed of the passing vehicle and the voltage peak value of the electric signal of the piezoelectric sensor, and transmits the obtained real-time roadbed modulus E, the speed and the weight of the passing vehicle to the computer terminal through the wireless transmission unit to realize real-time monitoring.

(4) When the monitored subgrade modulus E is attenuated by more than 30%, workers can go to the position located by the GPS positioning system to perform subgrade maintenance. When the monitored speed and weight of the set vehicle exceed the overspeed value v of the expressway_mOverload value M_mIndicating that the passing vehicle is over-speed or over-loaded.

Preferably, the monitoring system further comprises a spring for encapsulating the piezoelectric sensorAnd a rubber packaging shell. The piezoelectric sensor can be protected while well receiving waves transmitted in the soil. The piezoelectric sensor is a stacked nano zinc oxide sensor. The structure is shown in figure 2, the piezoelectric sensor made of nano zinc oxide has the advantages of high sensitivity and rapid reaction, five stacked nano zinc oxides can improve output electric signals, so that the monitoring is more sensitive, the vehicle weighing device is a film type soil pressure sheet, and the vehicle speed measuring device can pass through two piezoelectric sensors with the fixed distance of L according to a formula

And (6) obtaining.

In addition, for monitoring the speed and weight of passing vehicles, a highway overspeed value v can be set in the evaluation unit_mAnd an overload value M_mAnd the measured weight and speed of the passing vehicle are transmitted to the computer terminal through the wireless transmission unit, so that whether the passing vehicle has overspeed or overload and whether the roadbed modulus changes can be monitored simultaneously. The logical principle of operation is shown in fig. 3.

As shown in fig. 3, the logic principle of the analysis unit is as follows:

(1) setting an overspeed value v of a highway_mAnd an overload value M_mThe automobile weight of the automobile weighing device after the automobile passes through is input to the analysis unit, and whether the automobile weight exceeds M or not is judged_m；

(2) Then the electric signal output by the piezoelectric sensor is input to an analysis unit, and the analysis unit analyzes the electric signal to obtain the vehicle speed and v_mComparing and judging whether the automobile has overspeed or not;

(3) finally, the measured vehicle weight M, the measured vehicle speed V and the voltage peak value V output by the piezoelectric sensor are input to an analysis unit, the analysis unit carries out inverse calculation to obtain the roadbed modulus E, and the analysis unit enables the E and the locally recorded standard modulus E_bComparing, and judging whether the modulus is attenuated or not;

the combined system integrates highway speed measurement, weight measurement and road base monitoring modulus, so that the highway detection system is more comprehensive and more convenient.