Long-Duration Surface Anchoring With a Hybrid Electrostatic and Gecko-Inspired Adhesive

Many scenarios require access to locations that are difficult to reach; however, mobile and untethered robots for these applications operate on a limited reserve of energy. Researchers often design robots specifically to be able to wait for periods of time in low-power states, conserving energy, and protecting hardware during periods of inactivity. In this letter, we introduce a temporary anchor using a low-power hybrid electrostatic/gecko-inspired adhesive for robots such as quadrotors and wall-climbing systems to allow access to remote areas while providing the ability to safely hold a position for an extended duration. This letter presents a self-contained electrostatic and gecko-inspired adhesive anchor mechanism, which is particularly well suited for long-duration payload placement. With structural layers comprised of a rigid plate and a soft foam, this anchor distributes normal stress across the pad while maintaining the compliance required for effective use of the adhesives. This new approach to loading the hybrid adhesive increases the distance off-the-wall that a payload can be supported, even on rough surfaces. We model the capacity of the device and demonstrate carrying an 11.9 N load applied 12 mm off of a rough drywall surface with an adhesive area of 32 cm$^{-2}$. We also offer two innovations that extend the mission-duration of an electrostatic adhesive anchor. We show that polyimide, a common dielectric layer in flex circuits, is prone to failing over a period of hours while both polyethylene-terephthalate and polyethylene-napthalate films demonstrate long-term stability under the applied electrical field. Furthermore, to reduce the power consumption of the adhesive, we introduce the concept of power-cycling, and reduce power consumption by an order of magnitude while still maintaining over 85 percent adhesion strength.This temporary anchor can be scaled in size to suit a given application, with virtually no difference in power draw or required electronics.We model the payload capacity of the anchor, and demonstrate performance on a variety of surfaces.