| Soft robots are new robots that integrate materials science,bionics,engineering and other disciplines.Due to their own flexibility and infinite degree of freedom in theory,they have great application prospects in medical rehabilitation,rescue exploration and other fields,and attract the attention of many researchers.However,most of the soft robots driven by traditional artificial muscles such as shape memory alloys(SMA)and dielectric elastomer actuators(DEA)are faced with the problems of low integration,limited output force,high cost and poor environmental adaptability.A recently-discovered polymeric artificial muscle,twisted and coiled actuator(TCA),which can be easily fabricated from polymer fibers such as nylon fibers was introduced in 2014.It has the advantages of high energy density,low hysteresis and low cost.If using it as a driver to design a hexapod bionic soft robot which realize the lightweight integration of the robot,and has the ability of large load movement and adaptability to various environments,can further enrich the connotation of the field of soft robot and broaden the application field of polymeric artificial muscle(TCA).In this study,the motion mode of hexapod insects is described,and the feasibility of hexapod soft robot using bionic triangle gait for reference is analyzed.The structure design optimization of the bionic hexapod soft robot is carried out,and the design optimization of the soft foot of the core component of the robot is carried out by means of the finite element analysis software ABAQUS.In view of the fact that the silica gel material used for making soft foot belongs to hyperelastic material,it is difficult to obtain convergence solution by using thirdorder Yeoh model simulation analysis.A method of optimizing simulation analysis parameters based on experimental results and only carrying out fixed load analysis is proposed.The convergence problem of simulation analysis is successfully solved and the suitable structure of soft foot is obtained.According to this,the driving performance of polymer artificial muscle(TCA)is required.Based on the premise that the curvature of the foot is consistent,the relationship between the contraction of the artificial muscle and the bending angle of the foot is obtained.The gait of the robot walking in straight line and turning direction is planned,and the corresponding driving sequence of 18 artificial muscles is given.The actuation mechanism of polymer artificial muscle(TCA)is briefly described.The processing technology of polymer artificial muscle is studied to meet the driving requirement of hexapod bionic soft robot.The effects of processing load,annealing load and annealing times on the driving performance of single fiber wound artificial muscle were studied.Aiming at the electrothermal wire-attached artificial muscle,the effects of the type of electrothermal wire,the diameter of electrothermal wire and the ratio of electrothermal wire to polymer fiber on its driving performance were further studied.The driving performance of single fiber wound artificial muscle and electrothermal wire-attached artificial muscle was tested.The driving characteristics of artificial muscle are described quantitatively,and the artificial muscle which meets the needs of robot motion is finally obtained.Starting from explaining the driving and temperature closed-loop control strategy of a single polymer artificial muscle(TCA),the hardware control strategy of a hexapod bionic soft robot supporting 18 artificial muscle control is further extended.The hardware control circuit diagram is designed to realize the fabrication of integrated circuit board of robot control system.Using 3D printing technology and silica gel model casting technology,parts manufacturing and assembly of robot prototype are realized.The experimental system of the robot prototype was built,and the ability of the robot to walk in straight line and turn on the ground,to move with load and to move in water was tested. |
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