Research On Bionic Dexterous Finger Based On NiTi Shape Memory Alloy

As a smart material,NiTi shape memory alloy has broad application prospects in robots,aerospace,biomedicine and other fields because of its unique shape memory effect and superelasticity.Based on the design and manufacture of NiTi shape memory alloy bionic dexterous finger,the laser processing technology and resistance thermal drive mechanism of NiTi shape memory alloy are studied in this paper.Based on SMA laser processing technology,a direct component dexterous finger drive unit is designed.The SMA component realizes the bionic design of the three joints of human fingers,and can complete the bending and stretching movements under the action of a single resistance heat.In this paper,NiTi superelastic shape memory alloy wire with a Ni content of 51.51%(at%)was taken as the research object.It was remelted by Nd:YAG laser welding machine,and the microstructure and phase change behavior of SMA samples after laser processing were analyzed by means of metallographic analysis and DSC test.Laser processing technology experiments show that the phase transformation temperature of the SMA laser processing region is 30-50? higher than the base materials,and the joint region changes from the austenite state to the martensite state,which is characterized by shape memory effect.The shape memory effect can be locally realized on the superelastic NiTi alloy base materials by laser processing.Therefore,aiming at the different SMA memory effect requirements of different joint areas of dexterous fingers,optimized laser processing parameters were adopted in this paper to change the phase transformation temperature of SMA in different regions to realize its "multiple shape memory effect",and heat treatment was used to realize the initial shape setting of SMA components of dexterous finger.Furthermore,the resistance thermal drive performance of SMA-based dexterous finger was tested.The shape memory effect of different joints of dexterous finger was tested by experiments.The recovery angle-current-temperature relationship curves of different joint regions and the effect of current on the recovery rate are obtained.The twoway shape memory effect of SMA components was trained by thermomechanical cycle training,and the action characteristics were tested for the bending and stretching actions during the finger rehabilitation training.In this paper,the SMA component manufactured by laser processing realizes the local shape memory effect on the superelastic base material,which is expected to realize the flexibility,integration and intelligence of dexterous fingers.