We design, optimize and demonstrate the behavior of a tendon-driven robotic gripper performing parallel, enveloping and fingertip grasps. The gripper consists of two fingers, each with two links, and is actuated using a single active tendon. During unobstructed closing, the distal links remain parallel, for parallel grasps. If the proximal links are stopped by contact with an object, the distal links start flexing, creating a stable enveloping grasp. We optimize the route of the active flexor tendon and the route and stiffness of a passive extensor tendon in order to achieve this behavior. We show how the resulting gripper can also execute fingertip grasps for picking up small objects off a flat surface, using contact with the surface to its advantage through passive adaptation. Finally, we introduce a method for optimizing the dimensions of the links in order to achieve enveloping grasps of a large range of objects, and apply it to a set of common household objects.

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As a solution to the problem of scalable propulsion in small satellite architectures, the microfabricated ion Electrospray Propulsion System (iEPS) developed by MIT's Space Propulsion Laboratory has progressed to a point where it is ready to be characterized on a realistic testbed. In this paper, developments in the iEPS thruster design and testing equipment are outlined. Design changes address the performance and testing issues encountered with the first version. These changes include features to mitigate the formation of liquid current paths and ease grid-to-tip alignment and grid removal. Additionally, a 1-DOF free-floating CubeSat testbed with an integrated autonomous remote control system and high-voltage PPU has been developed and tested for use as a thrust balance and attitude control demonstrator.