Study On The Sensing Performance Of IPMC And Its Application

Ion-exchange Polymer-Metal Composites(IPMC for short)is a kind of intelligent material of Electroactive Polymer(EAP).Its performance is similar to that of biological muscle,so it is called artificial muscle.IPMC has attracted more and more attention in recent years.It has a lot of advantages,such as,light weight,good flexibility,and can be cut to any size and shape.Being applied low voltage,IPMC can produce large displacement;conversely,being given a mechanical bending deformation,it can produce some weak charges.It can work in a wet environment.Therefore,it is essential to research on sensing performance of IPMC,to develop force sensing characteristics,to design a micro-force sensor based on IPMC,to research on actuating and sensing performance of IPMC,and to develop a kind of integration end gripper.The gripper is suitable in wet or liquid working environment,and is high safety due to its low driving voltage,so it has great theoretical significance and practical value in biomedical engineering,micro manipulation Robots,bionic robots and other fields.(1)This paper develops a real-time online measurement platform for sensing performance of IPMC based on the Lab VIEW system,and realizes the online measurement of the sensing characteristics.The platform can exert the exciting force on the cantilever IPMC and obtain the deformation value of IPMC through the laser displacement sensor.The influence of water content on IPMC sensing voltage is tested.A large number of slow loading experiments are carried out to detect the sensing performance of the IPMC material.According to the basic characteristics of the intelligent material IPMC,the IPMC cantilever beam structure experimental samples are tested in different dimensions,exciting force exciting frequency and the amplitude of the working voltage of the vibration exciter.The sensing performance IPMC is fully grasped in various states.Based on the response values,a detailed sensing characteristic of IPMC database is established.(2)According to the design target of the IPMC cantilever beam force sensor,the filtering scheme is studied in view of the weak sensing signal characteristic of IPMC.Three filtering methods are adopted,which are the soft threshold method of the wavelet transform,the wavelet entropy and the LMS adaptive filtering method.By comparing with the wavelet transform and the wavelet entropy,the adaptive filtering method based on the LMS can make the IPMC weak signal get higher SNR and SNR gain,and the filtering effect is better.(3)Based on the differential equation of the deflection curve of the cantilever beam,the approximate equations of the deflection curve under the large and small deformation scales are derived.The modeling is made according to the mechanical properties of IPMC,and the relationship is obtained between the force and the deformation of the cantilever beam IPMC.Design the conditioning circuit for testing sensing performance of IPMC,including the design and development of charge amplification circuit and voltage amplifying circuit,being used for extracting weak current signal and amplify voltage signal to reach the range of signal acquisition module;design low pass filter to remove high frequency noise;design logarithmic amplifier circuit to improve the dynamic range of the IPMC micro-force sensor system.The mathematical model of IPMC deformation displacement and sensing voltage is obtained,and then according to the mathematical relationship between the force and deformation of the cantilever beam IPMC,the grey box theory model of the IPMC micro-force sensor is established.The measurement platform of the IPMC micro-force sensor is set up based on the micro-force sensor and the conditioning circuit of the sensing performance of the cantilever beam IPMC.We get the experimental model of the IPMC micro-force sensor,and complete the calibration of the main performance parameters.(4)By analyzing the creep characteristic model of IPMC material,the paper adopts the periodic output feedback control and PID control to solve the problem that the static load is difficult to be measured in sensing performance of IPMC.It establishes a PID control system based on IPMC creep model in the paper,then obtains and analyzes the experimental results.Finally,using the micro-force sensor of the IPMC cantilever beam,on the basis of Lab VIEW virtual instrument and the hardware,we build the actuating/sensing integrated gripper system,At the same time,according to the actual needs of the both actuating and sensing integrated end gripper of IPMC under the microscope,we complete the cell clamping experiment under the micro manipulation environment.