Design And Characteristic Analysis Of Flexible Joint Actuator For Soft Arthropod Robot

The design of soft robots generally follows bionic principles.Spiders rely on hydraulic system to extend their legs,but use muscles to make legs flex.The hydraulic-muscle codrive makes spiders combine flexible and lightweight structures with powerful movements,which perfectly meets the main requirements of modern robots.Taking the hydraulic joint of spider as the bionic object,the flexible joint and its driving characteristics of soft arthropod robot are preliminarily explored.The main work of this thesis is as follows:(1)A new type of double constrained pneumatic flexible joint actuator is proposed from the aspects of bio-inspired design and hydraulic-muscle codrive mechanism.According to its functional composition and structural principle,the manufacturing method of the actuator was studied.(2)The mathematical modeling of the flexible joint actuator is established,and the characteristic equation between the inflation pressure and the rotation angle of the joint actuator is obtained.The finite element simulation of the flexible joint actuator is carried out by ABAQUS.The rotation angle of the joint actuator is tested by experiments to verify the accuracy of the theoretical model.The test results are basically consistent with the theoretical model.(3)The driving characteristics of the flexible joint actuator are studied.The output torque and driving efficiency are tested and analyzed.The results show that under the pressure of 120 k Pa,the maximum rotation angle of the joint actuator can reach 28°,the maximum output torque can reach 0.42 Nm,and the driving efficiency can reach 0.56%.(4)In order to improve the output characteristics of the flexible joint actuator,a variety of fiber restraint structures are designed and manufactured,and the experimental tests are carried out.The results show that the performance of the actuator can be greatly improved by adding the constraint structure in the basal layer of the actuator,but the effect is not obvious by adding the constraint structure on the side layer of the actuator.The smaller the braiding angle of the base constraint structure is,the larger the output angle of the driver is.At 120 k Pa,the actuator angle can be as high as 38 ° when the constraint grid angle is 30 °.Compared with before,the rotation angle of the actuator is increased by about 36%,and the output torque and efficiency of the actuator are also greatly improved.(5)Finally,in order to verify the practicability of flexible joint actuator in soft arthropod robot,a double-joint soft arthropod robot is designed and manufactured.Then the motion characteristics of the robot are tested experimentally.The relationship between robot's moving speed,driving pressure and movement period is studied.In this thesis,the bioinspired design,theoretical modeling and experimental test is used to study the double constrained pneumatic flexible joint actuator,which shows the feasibility of the flexible joint actuator applied to soft arthropod robot.