Momentum Device Actuated Canfield (MoDAC) Manipulator

Development of a robotic manipulator called Momentum Device Actuated Canfield (MoDAC) Manipulator for integration on to the assistive free flyers (AFF) being developed by NASA for the International Space Station is proposed. Integrating a robotic manipulator with an appropriate end-effector to an AFF provides the capability to perform several autonomous functions such as material handling, fetching and handling tools, procedural support to astronauts during their experiments, etc. Additionally, it can help the AFF to dock into battery charging stations and perch by grabbing on to rails or other features on the ISS. Some of the technical challenges posed by incorporating a traditional multi-degree of freedom manipulator on an object of small inertia such as the AFF include complexity in attitude control and rapid depletion of battery (or propellant) due to (a) reaction disturbances caused by a joint motion and (b) Variation in the inertia of the AFF-manipulator system caused by manipulator movement. Additionally, mass, volume, and control issues are posed by utilizing a serial multi-DOF manipulator. Development of a parallel kinematic manipulator with a disturbance-free actuation mechanism will improve the performance of the AFF's attitude control system. Additionally, a manipulator-embedded mass property estimation scheme will complement the task of controlling the AFFs position and attitude. The proposed MoDAC manipulator achieves these objectives by using a reaction wheel based actuation method for a modified Canfield mechanism. Additionally, the manipulator electronics are embedded with a manipulator-inertia estimation algorithm that is transmitted to the AFF in real time for superior attitude control. The Phase 1 effort will demonstrate the technical feasibility to perform disturbance-free manipulator operations suited for Assistive Free Flyers such as SPHERES and HET-2 via high-fidelity simulations and proof of concept prototype development and testing.