Research On Bionic Design Of Flexible Tentacle Based On Liquid Crystal Elastomer Artificial Muscle

Deformation actuation of intelligent materials is a cutting-edge research hotspot in many fields,such as materials,mechanics,biology and so on.In recent years,a variety of software robot actuators based on shape memory alloy,magnetorheological fluid and liquid crystal elastomers emerge one after another,which continue to promote the development of software robots.In particular,liquid crystal elastomer（Liquidcrystalelastomers,LCEs）,as a thermally driven smart material that combines polymer networks and mesomorphic units,has attracted great attention of researchers because of its unique properties,such as large deformation（～40%）,reversible drive and strong scalability.As the preferred driving energy for modern industry and equipment,electric energy can be converted into thermal energy by Joule thermal effect,which can realize the programmable actuation of conductive LCE soft robot actuator.however,at present,most of the conductive LCE soft robot actuators are unidirectional deformation,and its application potential is limited by its driving structure.The specific work is as follows:Firstly,a LCE actuator composed of LCE artificial muscle and liquid metal polymer（Ga-Sn）-Si O₂)wire（LM）electrothermal film is proposed,and the effects of different structure parameters（LM pattern）and driving parameters（driving current）on the bending deformation of conductive LCE actuator are studied.The temperature change law of patterned LM-LCE actuator during electric bending is explored,and the bending mechanism of LCE with liquid metal wire pattern is revealed.It is found that with the increase of the applied current,the heating rate and saturation temperature of the LCE actuator also increase,and the maximum bending angle of the LCE actuator is proportional to the input current,that is,the larger the input current,the shorter the time needed to reach the maximum bending angle.Under 4 A input current,the average time for the actuator to reach the maximum bending angle is about 25 s,and the maximum bending angle is 116°.Compared with the triangular wave LM,concave LM,linear LM,sine wave LM,meandering LM and other pattern electrothermal film conductive LCE actuators,the square wave LM electrothermal film conductive LCE actuator has the best deformation effect.Secondly,a bi-directional driven"sandwich"structure conductive LCE actuator is designed creatively.The actuation performance of liquid crystal elastomer actuator with different surface characteristic pattern of liquid metal under external electric field was investigated.The influence of structural parameters on the bending deformation of soft actuator was analyzed by SOLIDWORKS finite element simulation.The stress distribution of electrobending of bi-directional LCE actuator was calculated.The electrobending performance of bi-directional driven"sandwich"structure conductive LCE actuator was studied.The effects of input electrical signal waveform,amplitude and frequency on the output strain and strain rate of artificial muscle are constructed,and the driving and control theoretical model of conductive liquid crystal elastomer artificial muscle is obtained.the optimal design structure and driving control method of conductive liquid crystal elastic actuator with bi-directional large deformation are mastered.In this paper,a new type of flexible operation end of artificial muscle with movable palm is constructed,and the regulation and control rules of outer clamp and inner support of different flexible objects and circular workpieces are studied.It is found that the maximum bending angle of the bi-directional driven"sandwich"structure conductive LCE actuator is proportional to the input current,and the maximum bending angle can reach 93.6°.The higher the current value,the higher the stable bending saturation temperature of the LCE actuator and the faster the heating rate.The electrothermal performance of sinusoidal LM-LCE actuator is the best,followed by square wave LM-LCE actuator.The maximum driving displacement of bi-directional LCE actuator can reach 17.62 mm under no load,and the maximum shrinkage displacement is 7.1 mm under 0.539N（55 g）load.The driving stress of the fixed length actuator is proportional to the applied current.When the current increases from 2.0 A to 4.0 A,the maximum contact force at the end of LCE is 40 m N,and the maximum driving stress increases from 0.17 Mpa to 0.96 Mpa,which is similar to the typical actuation stress produced by most mammalian skeletal muscles.On this basis,a multimodal LCE flexible tentacle is designed and developed,which can grasp the outer clamp and inner support of different flexible heterosexual objects and annular workpieces.The inner support can grasp the annular workpiece with the inner diameter of 50 mm,and the outer clamp can grasp the medicine bottle weighing 12 g.Finally,a new type of conductive LCE soft robot inspired by the movement of fruit fly larvae is developed.At the same time,the bionic creeping motion is realized based on the driving force induced by Joule thermal deformation and anisotropic friction.A conductive liquid crystal elastomer software robot imitating inchworm crawling is constructed.Under the condition of 3.0 V voltage,the maximum step displacement of the software crawling robot is 16.69 mm,the displacement attenuation is less than 25%,and the peristaltic speed is 7.38 mm/min.The crawling software robot with 3 times its own weight can reach 4.97 mm/min on a slope of 15°.By applying different voltage combination control to the left and right muscles of the software crawling robot,the turning radius of the crawling robot can be changed,so as to achieve the path control of the software crawling robot.The kinematics model of the software robot is established,and the validity of the established dynamic model is verified by comparing the experimental data with the predicted results.