Concentric Dual-Chamber Pneumatic Artificial Muscles: Miniature Actuators Designed for Use in Minimally Invasive Surgical Instruments

Abstract

Development of high-performance flexible surgical instruments is important to simplify and enable new minimally invasive surgical procedures. New actuation technologies are necessary to produce flexible instrumentation that is capable of accessing difficult-to-reach anatomy and performing laborious tasks without damaging delicate tissues. Recently, concentric McKibben muscles and dual-chamber pneumatic artificial muscles (PAMs) have been proposed for use in miniature flexible robotic surgical instrumentation. In this study, several varieties of a hybrid concentric dual-chamber PAM design are built and their force generation and stroke length are compared to a contractile McKibben muscle. The concentric dual-chamber PAM is designed to provide surgical access for large diameter (1.5-2.0 mm) instruments to be delivered to the surgical site in a pneumatically sealed actuator suitable for miniaturization and integration into surgical devices used in fluid environments (fetal applications in particular). Force output of the concentric dual-chamber PAM is modeled and compared to experimental results. Initial results suggest that the newly introduced design produces a higher actuation force per unit length than traditional McKibben muscles. The prototype dual-channel PAM produced a maximum 15.25 N of force and 8.39 mm of stroke, in comparison to 13.31 N of force and 19.3 mm of stroke produced by a traditional contractile McKibben muscle of the same length, outer diameter, and materials.