Insect-like drones have taken one large step closer to becoming a practical reality. Researchers at Harvard, MIT and the City University of Hong Kong have developed tiny insect-inspired drones that can not only maneuver in extremely tight spaces, but withstand bumps if things go wrong. The key is a switch to an actuation system that can flap the drones' wings while surviving its share of abuse. To date, drone makers wanting to go this small have had to ditch motors (which lose effectiveness at small sizes) in favor of piezoelectric ceramic-based rigid actuators. The new drones rely on soft actuators made from rubber cylinders coated with carbon nanotubes.
Existing soft actuators have persistent challenges that restrain the potential of soft robotics, highlighting a need for soft transducers that are powerful, high-speed, efficient, and robust. We describe a class of soft actuators, termed hydraulically amplified self-healing electrostatic (HASEL) actuators, which harness a mechanism that couples electrostatic and hydraulic forces to achieve a variety of actuation modes. We introduce prototypical designs of HASEL actuators and demonstrate their robust, muscle-like performance as well as their ability to repeatedly self-heal after dielectric breakdown--all using widely available materials and common fabrication techniques. A soft gripper handling delicate objects and a self-sensing artificial muscle powering a robotic arm illustrate the wide potential of HASEL actuators for next-generation soft robotic devices.
Typically, drones require wide open spaces because they're neither nimble enough to navigate confined spaces nor robust enough to withstand collisions in a crowd. "If we look at most drones today, they're usually quite big," says Chen. "Most of their applications involve flying outdoors. The question is: Can you create insect-scale robots that can move around in very complex, cluttered spaces?" According to Chen, "The challenge of building small aerial robots is immense." Pint-sized drones require a fundamentally different construction from larger ones.
In particular, small soft robots at millimeter scale are of practical interest as they can be designed as a combination of miniature actuators simply driven by pneumatic pressure. They are also well suited for navigation in confined areas and manipulation of small objects. However, scaling down soft pneumatic robots to millimeters results in finer features that are reduced by more than one order of magnitude. The design complexity of such robots demands great delicacy when they are fabricated with traditional processes such as molding and soft lithography. Although emerging 3D printing technologies like digital light processing (DLP) offer high theoretical resolutions, dealing with microscale voids and channels without causing clogging has still been challenging.
Researchers have long been trying to make electronics that are safe to eat. These include edible transistors, sensors, batteries, electrodes, and capacitors, which (if you put them together) are most of an edible robot. What's been missing so far has been the thing that makes a robot distinct from a computing system, and that's an edible actuator that would allow an ingestible robot to actually do something useful once you've swallowed it. At IROS last week, researchers from EPFL's Laboratory of Intelligent Systems, headed by Dario Floreano, presented a prototype of a completely edible soft pneumatic actuator made of gelatin. It probably doesn't taste very good, but it's biodegradable, biocompatible, and environmentally sustainable, and could enable all kinds of novel applications, as the researchers explain in their paper: The components of such edible robots could be mixed with nutrient or pharmaceutical components for digestion and metabolization.