Self-Preloading Flexible Attachment Actuator with Multi-Mechanism Hierarchical Structure

Flexible attachment actuators are popular in a wide range of applications,owing to their flexibility and highly reliable attachment.However,their reversible adhesion performance depends on the actual effective contact area and peel angle during operation.Therefore,a good actuator must ensure a uniform and reliable pre-pressure load on an adhesive surface,to increase the effective contact area of the attached surface,thereby maximizing adhesion.This study was inspired by fusion bionics for designing a hierarchical attachment structure with vacuum-adsorption and dry-adhesion mechanisms.The designed structure used the normal force under the negative pressure of a suction cup as a stable source of a pre-pressure load.By optimizing the rigid and flexible structural layers of the attachment structure,a load was applied uniformly to the adhesion area;thus,reliable attachment was achieved by self-preloading.The structure achieved detachment by exploiting the large deformation of a pneumatic structure under a positive pressure.The hierarchical attachment structure achieved up to 85%of the optimal performance of the adhesive surface.Owing to its self-preloading and reliable attachment characteristics,the designed structure can be used as an attachment unit in various complex scenarios,such as small,lightweight climbing platforms and the transport of objects in long,narrow pipelines.