Controllable adhesion, the ability to selectively attach or detach from a surface, is an essential capability for many engineered systems, such as material processing equipment, wall-climbing robots, and pick-and-place machinery. Robots capable of controllable adhesion have applications for inspection and repair, surveillance, and exploration of environments unsuitable for humans. [1,2] A variety of controllable adhesion techniques have been proposed to enable these use cases, including methods relying on pneumatic, electromagnetic, and dry fibrillar adhesive forces between a robot and a surface. While existing techniques are often effective, they usually require relatively heavy and energyconsuming components and/or intrinsically link high normal and shear adhesion.In this work, we develop an adhesion mechanism that relies on the fluidmediated adhesive force between an oscillatory plate and a surface. This lightweight, low-power mechanism provides high normal-but low-shear-adhesion, making it uniquely suitable for robotic applications including mobile robots and some manipulation tasks.Previous approaches have used active pneumatic adhesion (i.e., suction) [3,4] or strong electromagnets or permanent magnets [5] to demonstrate high adhesive stresses to enable wall climbing for relatively heavy systems (e.g., σ max ¼ 20.1 kPa for an individual suction unit weighing 0.8 kg [6] ). However, these approaches are, in general, limited to nonporous and ferromagnetic surfaces, respectively. In addition to surface restrictions, these systems usually require additional bulky hardware (i.e., traditional pumps and magnets). Despite these disadvantages, some pneumatic and electromagnetic approaches do have the advantage that they do not require direct contact with surfaces for adhesion. Thus, adhesion can be maintained while the manipulator or mobile robot smoothly slides across the adhering surface. This non-or light-contact mode of adhesion may be advantageous for mobile inspection robots that have to move easily across surfaces.Active pneumatic adhesion is advantageous in that pumps are commercially available and are relatively straightforward to control and integrate into a physical system. However, at small scales, these advantages are lost as the manufacturing of micro-electromechanical system micropumps [7] requires specialized high-precision equipment. Some studies have investigated

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Inflatable limbs have the potential to enable robots that are lightweight, deployable from a small package, and can navigate confined spaces. However, the load bearing capability of slender inflatable tubes is limited by buckling loads that occur with modest loading. In this work we explore the use of inflatable beams with layer-jamming skins that are compliant while deflated, but provide enhanced stiffness and load bearing capabilities when inflated. We first describe a fabrication method for the inflatable beam and present a model to predict the length scales at which jamming contributes to the overall performance of the inflatable beam. We then measure the performance of prototype jamming limbs using bending and tip-deflection tests to evaluate the ability of the jamming skin to mitigate the buckling failure inherent in inflatable beams. Finally, we incorporate four jamming-reinforced limbs into a mobile robotic system. To demonstrate the benefits of a hybrid rigid-soft mobile robotic system, we experimentally test the trade-off between walking more quickly with pressurized limbs (1 cm/s), versus navigating confined spaces with depressurized limbs (0.6 mm/s). Incorporating jamming reinforcement into inflatable beams provides improved stiffness and graceful failure rather than the catastrophic buckling that normally characterizes inflated cylindrical beams. Inflatable limbs augmented with pressure-based jamming are not drop-in replacements for rigid links. However, our results show that using layer jamming to provide nuanced soft to stiff capabilities may be valuable for specific environmental constraints.