Investigation of self-healing compliant actuators for robotics

Last 15 years, a wide range of self-healing (SH) materials has been developed and recently these materials are increasingly used in applications in multiple fields, like the automotive industry and aerospace. However, so far this material technology is not yet explored in robotics. The introduction of these materials in robotics will potentially reduce the over-dimensioning of current robotic systems, leading to lighter systems and eventually to more efficient designs. Compliant elements used in next generation soft robots, can be constructed from available SH-materials, making them able to autonomously heal cuts and perforations caused by sharp objects in unstructured environments. In addition, the use of SH-materials will have a beneficial impact on the life span of robotic components, reducing the required maintenance drastically. This paper presents the innovative concept of implementing a SH-mechanism in compliant actuators, using dynamic covalent polymer network systems based on the reversible Diels-Alder (DA) reaction. For two entirely different compliant actuators, a series elastic actuator (SEA) and a soft pneumatic actuator (SPA), an analysis is presented on the integration of the DA-polymers in the actuator designs. For both actuator types, a prototype was designed, developed and validated.