Novel Self-Sealing Mechanisms for Suction Cup-Based Soft Robotic Gripping

Suction cups are widely adopted in robotic gripping systems due to their adaptability and effectiveness in handling automated object manipulation tasks. Typically, multiple suction cups are employed to achieve enhanced adhesion and improved conformity to irregularly shaped objects. However, utilizing multiple suction cups often introduces significant challenges in ensuring airtight sealing. Even minor gaps at the suction cup-object interface can severely compromise airtightness, causing suction failure. To address these challenges, this study proposes two novel self-sealing mechanisms, termed SSM-NO (Normally Open) and SSM-NC (Normally Closed), which provide intrinsic self-sealing functionalities to suction cups. The SSM-NO mechanism allows suction cups to remain open during normal operation but automatically transitions to a self-sealed condition upon negative pressure application if an adequate seal is not initially established, thereby effectively preventing air leakage. Conversely, the SSM-NC mechanism maintains suction cups in a closed state under negative pressure, activating suction only upon slight physical contact with the target object. Integrating both SSM-NO and SSM-NC mechanisms in series further enhances vacuum line airtightness, even when SSM-NC-equipped suction cups fail to secure proper adhesion. Both proposed mechanisms can be readily integrated into various customized or commercially available suction cups without negatively impacting their standard gripping and releasing performance. This paper thoroughly details the design principles, operational theory, analytical validations, and manufacturing methods of the self-sealing mechanisms. Experimental evaluations confirm their feasibility and effectiveness, demonstrating their potential to simplify and improve suction-based robotic gripping systems.