| Flexible robots include industry-flexible robots and bio-flexible robots.Inspired by animals and plants in nature,bio-flexible robots are designed.This kind of flexible robots vary in scale and stimulating method from conventional robots.Especially,when the scale goes to micrometer-scale or centimeter-scale,it is with great difficulty to assemble powering device and controlling device.Functional material such as Shape Memory Alloy(SMA),Electronic Active Polymer(EAP),Liquid elastomer and piezoelectric material could deform following the pre-program model under the stimulation of external environmental factors.Once we apply functional material to bio-flexible robots,consecutive movement is supposed to appear when the robot is exposed to environmental temperature,moister,light,magnetic and electronic signalSo far,bio-flexible robots are actuated by pressed air,chemical energy,EAP,magnetic field,liquid elastomer,SMA and piezoelectric actuator.Except pressed air and chemical energy,other powering ways are all functional material.The essay reviews related researches in domestic and foreign and introduces 4D printing and its application in bio-flexible robots.In summary,the essay focuses on the proposal of a flexible robot which could be stimulated by various functional materialBy comparision,it is found that multi-layers robots could be separated to actuating part and moving part and it would be more convenient to analyze two parts respectively in theory.In this way,the theoretical research on moving part is generally meaningful To test the bio-flexible robots in experiment,the essay chooses piezoelectric material as the powering part.Besides,the essay summaries the schemes which achieve asymmetric friction and the essay uses array of micro structure to from asymmetric friction.The 3D printing technology is employed to fabricate the flexible moving part in that 3D printing could control the micro structure easilyThe flexible robot proposed in the essay is propelled by friction which is regularly regarded as resistence,but could supports motion.The flexible robot moves directionally,actuated by asymmetric friction that produced by micro structure.It is superior in simple structure,novel actuating principle and easy-controlling actuating signal.Unify of structure and function facilitates the manufacture and cuts down the costIn software Comsol,the essay simulates the natural model of the robot and the specific movement process in one cycle.At first,the static mechanical model is built to calculate the deformation of the piezoelectric vibrator.Then,the characteristic of the movement would be deduced in dynamic mechanical model.After that,the influences of structure parameters and power characteristics are tested in experiment.At last,the uniformity of the experimental and theoretical results is discussedTo simplify the structure and affluent the functions of the bio-flexible robot,the piezoelectric vibrator acts as both structural element and stimulating element.Not only excellent in high resolution,quick response and simple structure,the piezoelectric material could controlled by electrical signal which is available routinely.The robot introduced could be used in pipe inspection,earthquake rescue,medical delivery and precise location. |
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