Design of a Cable Driven Floating Robotic Arm with Continuum Joints

Long-reach manipulator shows potentials in inspection, search and rescue. However, the reach of such a manipulator is often limited, due to fact that the distal structures become payloads of the proximal joints. This research hence focuses on a proof-of-concept study of a slim long-reach robotic arm designed with continuum joints and floating links. A float link and a continuum joint constitute a module that is weightless due to buoyancy. The reach hence becomes unlimited in theory. The actuation of each joint is decoupled via a transmission arrangement, providing a simple kinematic model no matter how many robotic modules are used. Each floating link is composed of a from-the-shelf helium-filled Mylar balloon that is caged by acrylic rings. Each of the two-degree-of-freedom continuum joints is made from a super-elastic nitinol (nickel-titanium alloy) rod and actuated by three cables pulled by three stepper motors. Preliminary experimental results on this constructed 3-meter prototype show that the floating robotic arm can move with acceptable accuracy in still air, validating the proposed concept.