Variable-diameter Connector with Bistable Structure for Flat Tube Actuators

In this study, we develop a novel connector capable of easy connection between pneumatic flat tube actuators and widely used cylindrical inlet tubes. Flat tube actuators are widely used in the field of soft robotics. The flexibility of these actuators causes large change in their cross-sectional shape, making it difficult to connect conventional connectors, including tube fittings, to the flat tubes. Consequently, the typical approach has been to fix inlet tubes to flat tube actuators using adhesives. This method increases the complexity of fabrication and maintenance while simultaneously reducing the overall flexibility of the flat tubes. To address this issue, we propose a new connector, termed the BIDEX connector, which utilizes a bistable structure with two different diameters. This connector does not require special processing or additional structures on the flat tube actuators for connection. The BIDEX connector is installed on an inlet tube and one side is for connection with flat tube actuators while the other side is for connection with other tubes. In the connection process, the BIDEX connector is inserted into the flat tube, and its diameter is expanded by pushing the slider part of the connector, resulting in secure connection. Pulling the slider part causes the reduce in the diameter to facilitate the releasing. The simple connection and disconnection processes contributes to the rapid maintenance and reconstruction of the airflow path. This study presents the design of the proposed connector, and the experimental validation. The experiments validate the developed connector has a pressure resistance of more than 50 kPa for flat tube.