Abstract
The soft actuator possesses the characteristics of flexibility, environmental adaptability, and human–machine interaction. Firstly, aiming to resolve the limitation of variable stiffness performance of a traditional pneumatic artificial muscle (PAM) actuator, based on the antagonistic mechanism of extensor and contractor muscles, a novel pneumatic soft actuator coupled of extensor and contractor muscles is proposed in this paper. The actuator can perform the compound action of elongation/contraction, and the stiffness of it can be controlled by adjusting the elongation and contraction forces. Secondly, based on the deformation principle of woven and elastic fabric layers, the mechanical characteristics model of the actuator is established and simulated. The mechanical properties of the actuator are tested under different pressures and deformation displacement and the variable stiffness characteristics of the actuator are verified. Finally, actuators are utilized to manufacture a soft mechanical manipulator, which can achieve variable stiffness in a fixed bending attitude.
Highlights
Soft actuators are made of flexible materials or a few added rigid materials, and have the advantages of high flexibility and adaptability to complex environments
They have attracted extensive attention from institutions and scholars, that have made significant progress, such as the pneumatic artificial muscle made of elastic rubber and fabric [1], octopus-like tentacle robotics driven by shape memory alloy [2], and an artificial muscle driven by electroactive polymer [3]
Since the movement of the elastic body of the actuator depends on the deformation of the fabric, especially the characteristics of the material used in its construction, this article combines two anisotropic fabrics and elastomer to design contractor and extensor respectively
Summary
Soft actuators are made of flexible materials or a few added rigid materials, and have the advantages of high flexibility and adaptability to complex environments. A common feature of these variable stiffness principles is the dependence on elastomeric materials, such as urethane and silicon, for the soft actuator body. These materials possess many superiorities, including corrosion and heat resistance, the ability to co-mold multiple materials, and the ability to withstand large deformations when performing complex ranges of motion. The representative actuator is octopus-like tentacle structure [4,9], adopts the method of “transverse muscle” and “longitudinal muscle” to tighten the structure, achieving variable stiffness. It cannot perform the independently control of stiffness and position. We demonstrate the utility of the proposed actuators by integrating them into a soft manipulator that is capable of varying stiffness while keeping a fixed bending attitude
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