The use of bulk metallic glasses (BMGs) as the flexspline in strain wave gears (SWGs), also known as harmonic drives, is presented. SWGs are unique, ultra-precision gearboxes that function through the elastic flexing of a thin-walled cup, called a flexspline. The current research demonstrates that BMGs can be cast at extremely low cost relative to machining and can be implemented into SWGs as an alternative to steel. This approach may significantly reduce the cost of SWGs, enabling lower-cost robotics. The attractive properties of BMGs, such as hardness, elastic limit and yield strength, may also be suitable for extreme environment applications in spacecraft.

Dynamic surface grasping is applicable to landing of micro air vehicles (MAVs) and to grappling objects in space. In both applications, the grasper must absorb the kinetic energy of a moving object and provide secure attachment to a surface using, for example, gecko-inspired directional adhesives. Functional principles of dynamic surface grasping are presented, and two prototype grasper designs are discussed. Computer simulation and physical testing confirms the expected relationships concerning (i) the alignment of the grasper at initial contact, (ii) the absorption of energy during collision and rebound, and (iii) the force limits of synthetic directional adhesives.

This paper presents the development of a tool for grappling non-cooperative objects such as orbital debris and defunct or malfunctioning satellites. Using gecko-like adhesives, which can be turned ON and OFF and reused many times, the tool grapples objects by virtually any surface, significantly reducing the requirements on other systems like perception, GN&C, and control during the grapple sequence. Preliminary development is complete, including testing the adhesive on over 30 spacecraft surfaces, testing to over 30,000 ON-OFF cycles and to over 1 year of continuous hold, and testing in a thermalvacuum chamber at full vacuum and down to -60C (future tests should extend this down to -120C). Several iterations of the grappling tool have been designed, prototyped, and tested. A scalable design that uses many sets of opposed pads was validated grappling a representative piece of debris (33kg) in a rolling test on a flat floor with relative translational rates from 0 to 2 m/s and relative spin rates from 0 to 75 deg/s. Similar testing is currently underway on an air bearing flat floor.

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