Design And Development Of Negative Pressure Penumatic Soft Foam Actuator

With the advantages of theoretical infinite degrees of freedom,excellent deformation cushioning effect and high security of human-robot interaction,soft robots have a wide range of applications in high-tech and daily life.As the core element of a soft robot,the performance of the soft actuator is mainly determined by the materials and driven method,as well as determining the performance of the soft robot.Among them,pneumatic soft actuator is the most common and widely applied one.At present,most pneumatic soft actuators use flexible materials such as silicone and soft plastic,which can achieve larger deformation but have the problems of smaller output force and limited load capacity.Foam materials are characterized by low density,high compressibility and large deformability,which can satisfy the deformation needs and achieve large output force through the contraction of the aperture,using it to manufacture pneumatic soft actuators has unique advantages,but pneumatic foam soft actuators also have the shortcomings of single deformation mode and limited deformation effect.In order to achieve both motion characteristics and output force properties,in this paper,a negative pressure driven foam soft actuator is designed,which can realize omnidirectional bending and contraction of dual mode deformation as well as a has high output force.The main research contents and conclusions are as follows:(1)Based on polyurethane foam and bellows,a soft multi-cavity foam soft actuator is designed.The deformation mechanism of the actuator is analyzed,the structural and material parameters influencing the deformation of the actuator are determined through theory and experiment,the mathematical model of the bending deformation of the actuator is formulated and the motion space of the actuator is depicted by kinematic analysis,and the structural design rationality and the actuation feasibility is verified.(2)The foam soft actuators with different structural and material parameters were prepared,the test platform for the output characteristics of actuators was constructed,the motion characteristics,output force characteristics,response time and durability of the actuators under different air pressure were studied.The results indicate that the optimal actuator at 90 k Pa air pressure:(i)the ultimate bending angle is 56.2° and the maximum contraction rate is 47.9%.(ii)the maximum bending and contraction output force are 3.35 N and 7.2 N,respectively.(iii)A full loading and unloading process can be completed within 120 s and has good durability.(3)Based on the modularity principle,the series basic actuator modules were prepared,the negative pressure pneumatic control system with individual adjustment of each chamber was built,different numbers of basic actuator modules were connected in parallel to build a lifting device,a foam soft gripper,a quadruped-like soft robot and a hand-like claw soft robot and the functions and performance of different soft robots were investigated experimentally,the output capability of the foam soft actuator and its potential application in multiple scenarios was further verified.