Research On Key Technology Of Detection Circuit Of Biaxial Hair Flow Sensor Based On Weakly Coupled Resonators

There are many animals in nature obtain information about the external environment through their hair,such as crickets and spiders.Artificial hair flow sensor has the function of detecting velocity,wind direction,acceleration and vibration.The sensor designed by imitating animal hair can be well applied in the field of measuring wind speed,inertia and other external environment,and bring convenience for human production and invention.This paper takes the biaxial artificial hair flow sensor based on weakly coupled resonators independently designed by the laboratory as the research object.According to the sensitive mechanism of the sensor,the measurement and control method of the sensor is studied,and the detection circuit of the sensor is optimized.The main research contents of this paper are as follows:First,the working mechanism of the biaxial hair flow sensor based on weakly coupled resonators is analyzed.According to the stress analysis of the polym hair,a dynamic equation and a dynamic model are established for the biaxial hair flow sensor based on weakly coupled resonators.The weakly coupled resonant sensor measures air flow and oscillating flow based on amplitude ratio as the sensitive physical quantity.In this regard,the generation principle of oscillating flow and sensitive mechanism of the sensor are studied.In addition,electrostatic drive and capacitance detection are used to extract and process the signal.Then,in order to reduce the adverse effect of external noise on the sensor's detection of flow rate,a measurement and control system suitable for the weakly coupled resonant biaxial hair flow sensor is designed,including a phase-locked loop-based phase closed-loop system and an energy-conservation-based amplitude closed-loop system.The feasibility analysis of the system is realized by building a phase closed-loop system and an amplitude closed-loop system simulation module based on energy conservation in MATLAB/SIMULINK.The analysis establishes that the oscillating flow is extracted by the quadrature coherent demodulation method,and the demodulation of the oscillating flow is realized on the basis of the energy conservation phase-amplitude double closed-loop system.The entire closed-loop measurement and control system are simulated under the conditions of DC stiffness disturbance and oscillating current stiffness disturbance,and further verified the detection characteristics of the weakly coupled resonant hair flow sensor.Next,the detection circuit of the measurement and control system is studied.A closed-loop system detection circuit is designed,including signal pre-amplification circuit,amplitude processing circuit,power supply circuit.Appropriate hardware circuit chip and FPGA minimum system and its peripheral circuits are selected.According to the characteristics of the resolved signal,the corresponding algorithm in FPGA is designed,and the digital part of the signal is processed,including phase-locked loop,PI regulator,quadrature coherent demodulation algorithm and digital IIR filter.Finally,the FPGA-based weakly coupled resonant biaxial hair flow sensor detection circuit is fabricated,and the software description language is written and debugged accordingly.The open-loop characteristics of the weakly coupled resonators are tested,and the measurement and control method of the closed-loop system is experimentally verified.A air flow rate experiment platform is built to test the scale factor and bias stability of the sensor,which verified that the phase-amplitude closed-loop system based on energy conservation has better anti-interference ability than the amplitude open-loop mode.An oscillating flow experiment platform is built,the oscillating flow signals is demodulated using the coherent demodulation algorithm,and the mechanical sensitivity of the sensor is tested too.It is verified that the biaxial flow sensor based on weakly coupled resonators has good characteristics sensitive to flow rate.