Research On Pneumatic Soft Actuator Based On The Principle Of Magnetic-induced Variable Stiffness

Soft robotics is a cutting-edge direction in the field of robotics,showing good application prospects in flexible manufacturing,rehabilitation medicine,disaster rescue and other fields.Compared with rigid-body robots with precise movements and strong load output capabilities,soft-body robots composed of soft body structures and flexible drives generally have stronger human-machine-environment safety interaction capabilities.When the soft robot encountering environmental obstacles,it can adaptively change its body shape and recover when the constraints are lifted.However,the excellent motion flexibility of soft robots also directly hinders the improvement of operation accuracy and operation force output capability.This characteristic of "softness is more than rigidity" greatly restricts the application ability of soft robots.It is extremely important to improve the movement ability of soft robots with "combination of rigidity and flexibility",that is,the ability to actively adjust stiffness.Therefore,this paper focuses on the variable stiffness technology of soft robots,and proposes a pneumatic soft actuator based on the principle of magnetic-induced variable stiffness,focusing on the actuator design,stiffness modeling,and manufacturing process methods.The actuator has a fast,reversible and controllable stiffness adjustment capability.The specific work content is as follows:(1)The structure design and optimization method of variable stiffness pneumatic soft actuator is proposed.Combined with the magnetorheological stiffness effect of magnetorheological elastomer and the antagonistic pneumatic drive method,the magnetorheological elastomer material was used as the bulk material of the soft actuator,and a fiber-reinforced pneumatic soft actuator with variable stiffness was designed.Multi-cavity pneumatic soft body actuator.Through finite element simulation,the structural parameters of the fiber-constrained pneumatic soft-body actuator are optimized and the driving efficiency is improved.(2)The stiffness modeling and parameter identification methods of variable stiffness pneumatic soft actuators are proposed.By simplifying the actuator into a cantilever beam composed of multiple materials,combined with the magneto-rheological modulus model of the magnetorheological elastomer material,a mathematical model of bending stiffness is established,and the main influencing parameters of stiffness characteristics are analyzed.A parameter identification method for the stiffness of the device.(3)The casting manufacturing and test platform construction of the variable stiffness pneumatic soft actuator has been completed.Combined with the magnetorheological modulus model of the magnetorheological elastomer material,the magnetorheological elastomer material with the best stiffness adjustment ability was prepared,the casting mold based on the3 D printing process was designed,and the actuator was fabricated by the casting method.Software and hardware experimental platforms such as software actuator magnetic field adjustment device,pneumatic drive device and control system are designed and developed.(4)The variable stiffness pneumatic soft actuator is comprehensively verified.First,the bending performance and stiffness adjustment ability of the actuator were tested,and the stiffness model identification was completed.The experimental results showed that the stiffness of the actuator was increased by about 40% under the excitation of an average magnetic field of 65 m T;The experiment of maintaining the end position of the actuator under control shows that the load output capability of the actuator can be quickly and controllably adjusted through the active adjustment of the magneto-induced stiffness.The grasping ability of regular objects.The pneumatic soft actuator technology based on the principle of magnetic-induced variable stiffness proposed in this paper has the characteristics of fast,reversible and controllable stiffness regulation and high integration,and provides a new feasible idea for the variable stiffness technology of soft robots.