Piezoresistive sensor for internal pressure detection of expressway road bed

Abstract

The invention discloses a piezoresistive sensor for internal pressure detection of an expressway road bed. The sensor comprises a zero temperature compensating circuit (101), a sensitivity temperature compensating circuit (102), a ratio-voltage converting circuit (103) and a zero calibration value storage circuit (104), wherein the zero temperature compensating circuit (101) is used for compensating zero drift caused by temperature, the sensitivity temperature compensating circuit (102) is used for compensating the decreased sensitivity caused by temperature, and the ratio-voltage converting circuit (103) is used for providing a constant current source for a circuit, reducing the decreased sensitivity caused by temperature and magnifying difference-mode voltage output by a piezoresistive sensor bridge. By the aid of the sensor, the defect of a prior piezoresistive sensor in application is overcome, an actual use environment is combined, and output values of the sensor can be corrected.

Description

technical field [0001] The invention belongs to the field of sensor application, and in particular relates to a piezoresistive sensor used for internal pressure detection of expressway roadbed, which can automatically correct zero point offset and temperature drift. Background technique [0002] The safety monitoring of expressway structures is an important means to ensure the safe operation of highways. Among them, pressure is a very important parameter. The measurement of its value requires the use of pressure sensors. A device that varies the voltage of an electrical signal. With the rapid development of information processing technology and computer technology, sensors, as the front-end unit of various control systems, are becoming more and more important. The rapid development of sensor technology, behind which the huge market demand is the main driving force for development. Semiconductor force-sensitive sensors based on the piezoresistive effect of semiconductor mat...

AI Technical Summary

Problems solved by technology

[0003] The technology currently provided is: In general piezoresistive pressure sensor interface circuits, instrumentation amplifiers are used to amplify the differential mode voltage, but the instrumentation amplifier does not have the function of automatically clearing the zero offset voltage of the piezoresistive pressure sensor and suppressing the drift caused by temperature. Causes errors in measurement sensitivity and measurement results; the pressure of road structure and traffic flow cannot be distinguished, and the instrument amplifier cannot provide the constant current source or constant pressure source required by the pressure sensor

[0004] Existing solutions generally rely on manual adjustment, which wastes manpower and material resources, and after manual adjustment, because the adjustable potentiometer will have a certain degree of deviation with time, it generally takes time to adjust, and there are many problems in use. inconvenience

However, if the capacitor sample-and-hold circuit is used, it is difficult to ensure that the capacitor maintains a constant voltage for a long time due to the leakage problem of the capacitor, which is not suitable for the automatic calibration circuit of the piezoresistive sensor.

And it basically does not involve the influence of humidity on the measurement results of the pressure sensor

Constant current source or constant voltage source excitation is also implemented by building another circuit, which makes the circuit complex and cumbersome

[0005] Many existing pressure sensor circuits with self-calibration output are not designed to specifically suppress the temperature drift, but only a circuit that automatically adjusts the zero point is designed. Since the temperature will change over time, it cannot guarantee the accuracy of the zero point correction value for a long time. Consider the difference between the pressure in the structure due to the difference in water content and the pressure on the vehicle, and rarely consider the impact of sensor protection on its sensitivity

Images