Design And Realization Of Pneumatic Soft Snake-Like Robot

The traditional snake-like robot is a highly redundant rigid robot based on motor drive.Due to the poor environmental adaptability and flexibility of rigid materials,it cannot pass through narrow and rugged areas.But large deformed flexible materials are adopted by soft snake-like robots and some shortcomings of traditional snake-like robot can be overcome.Soft snake-like robots possess better adaptability and safety for unstructured environment,which have broad application prospects in military reconnaissance,terrain exploration,post-disaster search,pipeline maintenance,and other fields.Aiming at the relatively simple control modes of existing pneumatic soft crawling robots and the problem of poor control performance in complex environments,a wheel-walking pneumatic soft snake-like robot is presented.The fuzzy PID algorithm is adopted for the closed-loop feedback control of pneumatic system,so as to improve the control effect in crawling process.The main research contents of this thesis are as follows:Firstly,through the research on the movement mechanism of biological snakes,a soft robot with serpentine movement mode is designed.Finite element software is used to establish the simulation model of soft bending actuator.It is analyzed that the structural dimension of soft actuator and the different air pressures are of the influence on the bending deformation capacity.According to the simulation results,the optimal structural dimension parameters of soft actuator are determined.The relationship between the bending deformation angles of this actuator and different air pressures is obtained.In accordance with the determined structural dimension,the soft snake-like robot is made.Secondly,the data acquisition system of pneumatic soft actuator is introduced.The mathematical model of electro-pneumatic proportional valve is preliminarily established by utilizing mechanism method.Because many parameters of the mathematical model are difficultly determined,the pneumatic system of soft actuator is identified offline through experimental method combined with the data acquisition system so as to obtain the transfer function of pneumatic system and verify that the closed-loop system is stable.Simulation models of fuzzy PID controller and PID controller are respectively built and comparatively analyzed in MATLAB software.It is verified that fuzzy PID control strategy possesses obvious superiority in the pneumatic control system,which can effectively improve theresponse speed of pressure output of electro-pneumatic proportional valve.Finally,the experimental platforms are built respectively,on which the soft actuator and the soft snake-like robot are controlled.The fuzzy PID algorithm is compiled into the STM32 microcontroller to control the pressure output of electro-pneumatic proportional valve.After the bending deformation performance of soft actuator is tested,the driving air pressure of soft snake-like robot is selected as 25 k Pa.The deformation response time of each actuator under action of PID algorithm and fuzzy PID algorithm is measured based on this pressure,and the corresponding control sequence diagrams are plotted.The crawling motion of soft snake-like robot in the plane and on the slope is tested by experiments.The results show that the average climbing speed of soft snake-like robot controlled by the PID algorithm in the plane is2.63mm/s.The average climbing speed of soft snake-like robot based on the fuzzy PID algorithm in the plane is 3.15mm/s,and the maximum climbing angle is 19°.The above results show that the fuzzy PID algorithm is superior to the PID algorithm in the response speed of the control system,which can improve the control effect in the crawling process.