| Magnetically Controlled Shape Memory Alloy(MSMA)is a new type of intelligent material with the advantages of large strain and fast response,which is suitable for use as a sensitive element in sensors.In this paper,based on the inverse effect of the MSMA shape memory effect,the sensor structure is optimised and designed,and the optimised sensor structure is simulated and studied using COMSOL software.The noise of the sensor induced voltage is filtered by DSP,and the MSMA sensor is experimented by the constructed experimental platform,aiming to obtain a sensor with better performance and a sensing signal without noise interference.The main work is as follows:The working principle,microstructure and deformation mechanism of the MSMA sensor are described.The magnetic field at each part of the working air gap is difficult to visualise.FEA is used to calculate the magnetic field and flux density at each part of the working air gap,and the results are plotted in COMSOL,providing a theoretical basis for the optimised design of the MSMA sensor.The structure of the MSMA sensor is optimised to address the problem that the permanent magnets providing the bias magnetic field will add an air gap to the magnetic circuit,resulting in an increase in reluctance.The placement and distribution of the permanent magnets can be reasonably designed to effectively reduce the reluctance in the magnetic circuit,thereby reducing the excitation power and increasing the induced voltage output value.The simulation results show that the optimised MSMA sensor increases the flux density of the working air gap and reduces the excitation power of the coil.The experimental platform was used to conduct experiments on the MSMA sensor and the results showed an increase in the induced voltage amplitude of the optimised sensor,which verified the correctness of the optimised sensor structure.The signal processing system for the MSMA sensor was designed with the INDUS TMS320F28335 DSP as the core processor.The AD7606 and AD5344 chips were selected for signal acquisition and digital-to-analogue conversion,and the software design for signal processing was carried out in Code Composer Studio 8.0 to provide an experimental basis for signal processing.The VSLMS(Variable Step-Size Least MeanSquare)algorithm is used to process the sensed signal.The VSLMS algorithm corrects the weight coefficients according to the mean-square error,so that the noisy sensed signal is constantly approximating the ideal signal.The VSLMS algorithm processes the output sensing signal,correcting the weight coefficients according to the mean square error,so that the noisy sensing signal continuously approximates the ideal signal and finally agrees with it.The filtering results show that the algorithm can effectively filter out the noise in the sensing signal and extract the voltage sensing signal of a single frequency. |
