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Design And Experiment Of Soft Robot Based On Shape Memory Alloy

Posted on:2020-08-23Degree:MasterType:Thesis
Country:ChinaCandidate:W H WangFull Text:PDF
GTID:2428330575499002Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
Soft robots are usually made of soft materials and can be arbitrarily changed in shape and size over a wide range.They have broad application prospects in the fields of reconnaissance,detection,rescue and medical treatment.Compared with traditional rigid robots,software robots have many advantages: they have better environmental adaptability,can be compatible with obstacles through deformation;can make robots in different shapes and realize motion through active deformation;active deformation and passive With the combination of deformation,the robot can pass through the gap smaller than its own shape and enter the space that the traditional robot can't enter;it can imitate the movement pattern of animals in nature,adapt to the environment that humans can't reach,expand the field of human exploration,and be the future robot development.The new direction.With the continuous advancement of technology and the continuous development of smart materials,the driving structure of robots is made of intelligent materials with similar muscle properties and sensing functions.It has simple structure,good environmental adaptability,low noise and the ability to actively generate complexities.Therefore,it has gradually become the future development trend of software robots drives.In order to apply shape memory alloy(SMA)to the structure of soft robots,the mechanical properties of SMA are analyzed,and the manufacturing and design methods of SMA spring are given.In order to obtain the relationship between heating current,load,output displacement and recovery speed of SMA spring,an experimental platform is built to carry out experimental research.The experimental results show that the designed SMA spring has good mechanical properties.The effective displacement increases with the increase of load,and decreases with the increase of load when the load exceeds 0.32 N.Increasing the heating current can greatly improve the recovery speed of SMA spring;the recovery speed of SMA spring is proportional to the heating current and inversely proportional to the load load;the response speed of SMA spring is affected by the cooling speed,and the speed in cooling process is proportional to the heating electric.The mechanical properties of SMA spring were tested,which laid a foundation for the development of the robot.According to the motion law of inchworm,a new type of soft robot is designed.The trunk structure which can bend and deform is simulated by inchworm trunk design.SMA spring is used to simulate inchworm muscle to drive the trunk structure.Soft robot can realize continuous motion by periodically switching on and off current of SMA spring and imitating the motion law of Inchworm by using friction difference between forefoot and hind foot bristles.The prototype of the software robot is made,and the control parameters of the software robot are determined by experimental method.The experimental system was built,and the robot was placed on rubber pad,wood board and cardboard for motion experiment.The experimental results show that the current frequency and duty ratio have a great influence on the crawling speed of the software robot.The fastest crawling speed on the three surfaces occurs in the range of frequency 0.14-0.16 Hz and duty ratio 25-30%.The maximum crawling speed of the robot can reach 3.43 mm./ S;The designed software robot is suitable for crawling on soft and rough surfaces,but not on hard and smooth surfaces.The designed software robot can imitate the motion of inchworm,which shows the feasibility of the designed software robot and provides a new idea for the design of the software robot.In order to improve the crawling speed of the inchworm-like software robot,the structure of the robot was improved,and a fast crawling inchworm-like software robot was designed.By increasing the driving current,the speed of the bending stage is increased,and by increasing the stiffness of the trunk,the speed of the straightening stage is increased.The response speed of the soft robot is improved by combining the two.In order to verify the validity of the design idea,a trunk structure with greater stiffness is designed to replace the flexible silicone skin,so that it can obtain greater resilience in the process of bending deformation.Through the force analysis in the process of deformation of the robot,the model of heating time and single period displacement of the robot is obtained by combining the electrothermal model and SMA spring model.A prototype of the robot is made for experimental verification.The results show that the simulation results of the single period displacement model are basically consistent with the experimental results.The crawling performance of the robot is experimentally studied through the experimental test system.The experimental results show that the improved robot can achieve the fastest crawling speed of 4.1 mm/s in the area with frequency of 0.17-0.18 Hz and duty cycle of 27.5-32%,which is 20% higher than the crawling speed of the robot designed in Chapter 2.The correctness of the design idea is verified.A new type of soft robotic fish is designed according to the motion law of Manta fish.The robot fish consists of flexible fin structure,base plate and tail fin which can simulate the shape of Manta fish to achieve up and down swing motion.SMA wire is used to simulate the muscle of Manta fish to drive the flexible fin structure.Flexible pectoral fin structure can imitate the upper and lower oscillation of Manta fins by periodically switching on and off voltage of SMA wires arranged on the upper and lower sides,so as to generate driving force and realize swimming motion.In order to validate the designed robot fish,a prototype of the robot fish was made.The driving voltage was determined by experimental method,and the driving strategy of the robot fish was determined by thermodynamic analysis of SMA wire.The experimental platform was built and swimming experiments were carried out.The experimental results show that the maximum swing angle of the flexible fin structure is 42 degrees.The fastest swimming speed of robot fish occurs when the driving voltage frequency is 2.6 Hz and the duty cycle is 21%,and the fastest swimming speed is 23.4 mm/s.The designed fish can imitate the swimming of Manta fish,which provides a good experimental basis for the study of robot fish.
Keywords/Search Tags:SMA, software robot, bionic robot, inchworm movement, robot fish
PDF Full Text Request
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