•A pneu-net actuator with coupled bending and twisting motion is designed.•The motion of the actuator can be programmable by adjusting the chamber angle.•Both the FEA and experimental results are ...presented to verify the development.•The actuator can dexterously grasp different objects with various sizes or shapes.
Soft pneumatic network (pneu-net) actuators are widely employed for achieving sophisticated motions. However, to produce bending and twisting simultaneously in a single pneu-net actuator is challenging. In this paper we present a programmable design to enable pneu-net actuators to achieve such complex motions. This achievement is mainly owing to tuning a structure parameter, the chamber angle. Through finite element analysis and experimental verification, variation trends of bending and twisting motions with respect to the chamber angle are investigated. Additionally, deformation characteristics of actuators are demonstrated by depicting configurations of actuators and some grasping tests. By adjusting the chamber angle, the motion of pneu-net actuators is explored into 3-D space and becomes more sophisticated and dexterous. This programmable design method guides the design of pneu-net actuators, making them promising candidates for more complicated and advanced applications.
Soft actuators are compliant structures that are generally made of elastomers and generates large deformation. The behavior of these structures cannot be estimated accurately using infinitesimal ...strain theories. The objective of soft robotics applications is the controlled large deformation of these structures. In this article, we propose an analytical model for a pneu-net soft actuator. The model is based on the Euler-Bernoulli finite strain hyperelastic thin cantilever beam theory. The deformation of the air chambers is modeled using finite strain membrane theory. The analytical model is developed for two different states of the actuator: 1) free space; and 2) when the actuator was subjected to tip contact. The proposed theoretical model predicts the deformation and force characteristics of the actuator for the grasping state. The theoretical formulation of the developed model is different from previously developed infinitesimal strain models for the actuator, as it considers the axial stretch and forces applied to the actuator. In addition, it can be theoretically implemented on similar structured actuators for various applications. The theoretically calculated deformation and force characteristics of different actuators are compared with the finite element (FE) model and experimental characteristics. The results suggest that the proposed model can predict the actuator deformation and force characteristics as accurately as the FE model, but the computation time of the proposed model is less than 1% that of the FE model. The proposed model is further implemented on a three-finger gripper to predict the air pressure required for a stable grasp of different objects and is validated experimentally.
•Pneumatic, soft robot actuators are examined experimentally and with numerical models.•A five parameter constitutive model is shown to be applicable to a wide range of pneumatic ...actuators.•Constitutive models are validated using experiments and finite element models.•Intrinsic curvature of the actuator has a non-uniform lengthwise profile but varies linearly with pressure.
While soft robots have many attractive features compared to their hard counterparts, developing tractable models for these highly deformable, nonlinear, systems is challenging. In a recent paper, the authors published a non-classic, five-parameter constitutive relation for a rod-based model of a widely used, pneumatically actuated soft robot arm. It is natural to ask if the complexity of the relation can be eliminated by redesigning the actuator? To this end, finite element models and experimental results are used to further explore the five-parameter constitutive relation. For multiple designs of the pneumatically actuated soft robot arm, we are able to demonstrate how finite element models can be employed in place of experiments to specify the constitutive relations and how the relations are scalable by actuator length and applied pressure. Our primary result is the finding that the five-parameter constitutive relation is germane to pneumatically actuated soft robot arms and the parameters for this relation can be determined by three finite element simulations.
Soft pneumatic network (Pneu-net) actuators are frequently used to achieve sophisticated movements, but they face challenges in producing both bending and twisting motions concurrently. In this ...paper, we present a new Pneu-net twisting and bending actuator (PTBA) design that enables them to perform complex motions. We achieved this by adjusting the chamber angle, ranging from 15 to 75 degrees, to optimize the bending and twisting movements through finite element analysis and experimental verification. We also investigated the variation trends in bending and twisting motions and determined the actuator’s workspace and maximum grasping force for a variety of objects with different shapes, materials, and sizes. Our findings suggest that PTBA is a promising candidate for advanced applications requiring intricate and bioinspired movements. This new design method offers a path toward achieving these goals.
Pneumatic actuators (referred to as pneu-nets) are drawing increasing attention due to their high customisability, ease of fabrication and innate softness. The actuator's ability to bend is one of ...the important parameters characterising its performance and related to its structure. Some structures are developed. In this work, a new structure (NS) pneu-nets is developed, and its bending ability is compared with the currently common Mosadegh pneu-nets structure (developed by Mosadegh). These two are analysed in two aspects: the trajectories of the pneu-nets actuator's tip, and the defined angle of bending. The results indicate that the NS pneu-nets actuators are able to achieve greater bending at higher pressures and can be lightweight. These pneumatic actuators provide improved structure for soft robotics.
Natural animals always provide inspirations for soft robot designs, and the evolved locomotion mechanisms perfectly adapted to specific environments motivate a lot of robots to pursue superior ...mobility. The small stomatopod named Nannosquilla decemspinosa possesses a unique form of locomotion-backward somersaulting which allows the animal to move flexibly and rapidly on soft and moist sand. In this letter, we present a bio-inspired dynamic somersaulting soft robot (SomBot) with ultra-fast moving speed (maximum speed is over 0.94 m/s). To mimic the unique somersaulting of the stomatopod, a simple prototype containing a pneu-net actuator body and a suction is developed. With the help of the controllable anchoring exerted by the suction, the curling deformation of the body actuator can be converted into the fast somersaulting movements. The dynamic somersaulting mechanism is modelled and analyzed. Deformation tests are conducted for the body actuator to provide guidance for the somersaulting control. The fully soft SomBot prototype exhibits a much faster speed (9.2 body lengths per second) than the reported fast-moving soft robots, which demonstrates the dynamic somersaulting mechanism has great potential for designing soft locomotion robots with superior mobility.
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