Overview and Performance of the Front-End Robotics Enabling Near-Term Demonstration (FREND) Robotic Arm

On-orbit servicing of spacecraft offers the attract ive possibility of extending the life of existing military and commercial spacecraft. Sever al of the technical challenges and risks associated with on-orbit servicing have already bee n mitigated during the Orbital Express mission, in which a satellite outfitted with dockin g interfaces tailored to the specific mission was successfully grappled. One of the key remainin g technical challenges associated with on-orbit servicing is the ability to service satell ites that are not designed with custom grappling interfaces, which constitute the majority of current on-orbit satellites. The goal of the DARPA-sponsored FREND program is to overcome this challenge and develop, demonstrate and ultimately fly robotic manipulator technologies designed to autonomously perform unaided grappling. One of the key components of the FREND mission is the development of a seven degree-of-freedom (DOF) flight robotic arm that can be used to grapple, inspect, and service most of today’s space craft. This paper presents the capabilities of such robotic arm and discusses its performance w ith respect to on-orbit servicing tasks.