Pneumatically Controlled Reconfigurable Bistable Bionic Flower for Robotic Gripper.

Beyond their colorful appearances and versatile geometries, flowers can self-shape-morph by adapting to environmental changes. Nature-inspired artificial systems that mimic their natural counterparts in function, flexibility, and adaptation find an emerging application in mobile robotics. In this study, a novel reconfigurable bionic flower made of petal-shaped bistable carbon fiber-reinforced composites and actuated by soft pneumatic actuators is presented. A robotic gripper based on the bionic flower was then developed for transportation tasks. First, a bionic petal based on a hybridization of bistable composites was designed and a theoretical model was established to analyze its bistable characteristic. Second, experiments and simulations were performed to analyze the out-of-plane deformation and morphing processes of the bionic petal. Curvature analysis of the closing state and blooming state shows a good match with the theoretical results. Finally, a flower-inspired robotic gripper made of the bionic petal is demonstrated to evaluate its gripping performances, including gripping force, response time, and reliability. The functional tests confirmed that the proposed soft gripper can grip objects of various shapes, sizes, and weights within milliseconds response time. The stable gripping configuration was maintained through the bistability of the bionic petal without continuous pressure consumption. The high reliability of the gripper is very useful for gripping tasks under unstructured environments, where precise control over the robot is not possible.

Pneumatically Actuated Soft Gripper with Bistable Structures.

This study presents the design and test of a novel self-adaptive soft gripper, integrating pneumatic actuators and bistable carbon-fiber reinforced polymer laminates. The morphology was designed using the distinct structural characteristics of bistable structures; and the stable gripping configuration of the gripper was maintained through the bistability without continuous pressure application. The sufficient compliance of bistable structures makes the gripper versatile and adaptable to gripping deformable objects. First, a pneumatic-actuated method was introduced to achieve the reversible shape transition of the bistable structure. Next, three arrangement methods for actuators were analyzed with respect to the bistable transition and curvature, where it was found that the cross-arrangement is optimal. The effects of pneumatic actuators with different geometrical parameters on the response times are discussed, and the results show that the bistable structure can achieve shape transition within milliseconds under low pressure. Furthermore, the numerical and experimental results show good agreement between critical pressures and out-of-plane deformation. Furthermore, the shape retention function of the soft gripper was studied by using it to grasp objects of various sizes even when the pressure was reduced to the initial state. The bistable laminates exhibit sufficient compliance, and the deformed laminates can automatically accommodate the deformation of objects. The relationship between the weight and size of available gripping objects was studied; functional tests confirmed that the proposed soft gripper is versatile and adaptable for gripping objects of various shapes, sizes, and weights. This gripper has immense potential to reduce energy consumption in vacuum environments such as underwater and space.