Development of a 3 Degree of Freedom Manipulator for Use on a Planar Microgravity Testbed

This work presents the development of a compact, low-mass robotic manipulator system designed for autonomous object interaction in microgravity environments. Testing of an initial prototype and development of a final proposed manipulator is discussed. The proposed manipulator has been designed to fit within a 3U CubeSat form factor. The system consists of a planar 3 Degree-Of-Freedom (DOF) revolute joint robotic arm. The end-effector features underactuated prongs that will utilize geCKo adhesive tape for shear force retention and reliability in object acquisition. The primary research goal is to characterize the manipulator's performance through experimental validation. This was completed through ground based testing to study the multi-body dynamics. Primary testing of the manipulator was completed on a flat test surface with a fixed base. These tests showed successful actuation capabilities with an inverse kinematic algorithm. Test results presented within this paper suggest significant mechanical play at the joints, which motivated a redesign of the manipulator. Testing of the redesigned manipulator showed successful actuation capabilities with significantly less mechanical play. Building on these results, future work plans to adapt the proposed manipulator to a dynamic base using a floating air bearing platform. This shall enable three additional Degrees-Of-Freedom (2 axis translation and 1 axis rotation) to the 3 DOF manipulator. This work and related future work aim to develop a ground based analog to simulate in flight dynamics for missions related to on-orbit assembly and maintenance, sample acquisition, and inspection and health monitoring of larger spacecraft.