Abstract
In the landscape of Industry 4.0, advanced robotics awaits a growing use of bioinspired adaptive and flexible robots. Collaborative robotics meets this demand. Due to human–robot coexistence and interaction, the safety, the first requirement to be satisfied, also depends on the end effectors. End effectors made of soft actuators satisfy this requirement. A novel pneumatic bending soft actuator with high compliance, low cost, high versatility and easy production is here proposed. Conceived to be used as a finger of a collaborative robot, it is made of a hyper-elastic inner tube wrapped in a gauze. The bending is controlled by cuts in the gauze: the length and the angular extension of them, the pressure value and the dimensions of the inner tube determine the bending amplitude and avoid axial elongation. A design methodology, oriented to kinematically mirror the shape of the object to be grasped, was defined. Firstly, it consists of the development of a non-linear parametric numerical model of a bioinspired finger; then, the construction of a prototype for the experimental validation of the numerical model was performed. Hence, a campaign of simulations led to the definition of a qualitatively predictive formula, the basis for the design methodology. The effectiveness of the latter was evaluated for a real case: an actuator for the grasping of a light bulb was designed and experimentally tested.
Highlights
One main trend of the fourth industrial revolution, better known as Industry 4.0, is advanced robotics, as proposed in [1]
According to the specifications and guidelines defined in [2], safety is addressed by constructors through proper hardware, proper software and lower performance than traditional industrial robots
This result validates that the formula that can be adopted in substitution for the finite element (FEM) model for the design of the proposed type of soft actuator
Summary
One main trend of the fourth industrial revolution, better known as Industry 4.0, is advanced robotics, as proposed in [1]. The braided shell, with a constant braided angle, can be wrapped around a tube with a non-constant rectangular section, as a wedge [28]; it is possible to adopt the same solution around a tube with a constant rectangular section, or with a semi-circular section in which a surface is covered by an inextensible material [29,30,31] Both classes provide for the bending of all soft joints in the same direction, like the behavior of the human finger. In addition to the previous topics, the novel aspect of the proposed actuator is in its conceptual design: a hyper-elastic tube, that can be commercially available in different sizes and lengths, can be inserted into a partially rigid external structure with cuts placed with precision, according to a formula developed for their design, and is easy to realize, on the basis of the shape of the object to be grasped. The effectiveness of the design methodology is demonstrated in a practical application: the design of an actuator whose shape kinematically mirrors the shape of a light bulb
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